The prepared graphene powder comprised abundant slit nanopores and micropores, showing a large specific surface area of 653.2 m2/g with a microporous surface area of 367.2 m2/g under optimized conditions. The pore structure was easily tunable by controlling the oxidation degree of GO and by the second annealing process. When the graphene powder was used as the supercapacitor electrode, a specific capacitance of 372.1 F/g was achieved at 0.5 A/g in 1 M H2SO4 electrolyte, which is a significantly enhanced value compared to that obtained using activated carbon and commercial reduced GO. The performance of the supercapacitor was highly stable, showing 103.8% retention of specific capacitance after 10,000 cycles at 10 A/g. The influence of pore structure on the supercapacitor performance was systematically investigated by varying the ratio of micro- and external surface areas of graphene.Herein, we introduce a simple method to prepare hierarchical graphene with a tunable pore structure by activating graphene oxide (GO) with a two-step thermal annealing process. First, GO was treated at 600 °C by rapid thermal annealing in air, followed by subsequent thermal annealing in N To enhance their performance, the electrode materials are required to have a high specific surface area and suitable electrical conductivity; several carbon materials, such as activated carbon, carbon nanotubes, and graphene, have been widely utilized to meet these requirements10. In particular, hierarchical graphene comprising both micro- and mesopores is desirable for fabricating high-performance supercapacitors, because the micropores provide a high specific surface area for ion adsorption and the mesopores facilitate ion transport12. Moreover, graphene is highly conductive, and thus, can efficiently collect electrons on the metal electrode surface14.Supercapacitors are efficient energy-storage devices owing to their advantages, including high power density, fast charge/discharge rates, stable operation over a wide temperature range, and long cycle life17, template approach19, chemical vapor deposition (CVD)25, and chemical/thermal activation30. Graphene oxide (GO) can be self-assembled in the form of a macroporous scaffold in its concentrated solution15 or during a hydrothermal treatment16, and the graphene scaffold can be used as an electrode after reduction17. The template approach uses a sacrificial nanomaterial, such as polystyrene nanoparticles, as a template, which can be removed by a chemical or thermal etching process, leaving a graphene scaffold19. CVD deposits a graphene layer on macroporous metal catalysts, including a Ni/Cu mesh, a metal nanowire, and metal nanoparticles, by treating the hydrocarbon and hydrogen gas at high temperatures25, and the metal catalyst is etched away using an acidic solution. Chemical activation is effective for preparing porous graphene in the form of bulk powder, which is generally conducted at 450–900 °C in the presence of activation agents such as KOH, H3PO4, and ZnCl2 to facilitate the transformation of solid carbon of graphene into CO2 and CO gas, leaving defective nanopores30. Although the above methods are effective for preparing porous graphene, the preparation processes are laborious because additional steps are required to remove the added chemicals or templates and the pore structure can be hardly controlled in the microporous dimension31. Therefore, a simple and scalable preparation method for graphene with a tunable pore structure is required to accelerate the commercialization of high-performance supercapacitors using graphene-based materials.Several methods have been suggested to prepare nanoporous and hierarchical graphene structures, such as self-assemblyIn this study, we developed a simple method to tune the hierarchical and porous structure of graphene materials through thermal annealing of GO without additional processes or additives. It was demonstrated that the micro- and mesopores of graphene can be precisely tuned by controlling the oxidation degree of GO, which was used as a starting material for thermal activation. The pore structure, particularly for micropores, was further modified by the second annealing treatment of the as-prepared nanoporous graphene in an inert environment. In addition, the influence of the hierarchical pore structure of graphene on the electrochemical performance of supercapacitors was systematically investigated.33. The ratio of graphite and KMnO4 was fixed at 3.5 for all GO preparation procedures. First, 2 g of graphite powder was added to 150 mL of sulfuric acid and stirred to form a homogeneous graphite solution. Then, potassium permanganate  was gradually added to the graphite solution while stirring in an ice bath to cool the solution. After stirring for the desired time in a water bath at 35 °C, the solution was placed in an ice bath and 200 mL of deionized (DI) water and 100 mL of hydrogen peroxide (H2O2) were slowly added in sequence. The stirring time was varied from 30 min to 10 h to observe the influence of oxidation time on the pore structure of reduced GO (rGO) after rapid thermal annealing. Next, vacuum filtration was conducted to filter the resulting product with a cellulose filter and washed several times with DI water to remove the remaining chemicals. The filtered GO cake was dispersed in DI water and frozen for 48 h in a refrigerator, and then freeze-dried to obtain sponge-like GO powder.Graphite  was purchased from Sigma Aldrich and used as-received without purification. It was oxidized using a modified Hummer’s method34. After rapid thermal annealing, the quartz tube was removed from the furnace and cooled down to room temperature naturally. After thermal annealing, the brown color of GO turned black. The resulting product, activated reduced graphene oxide (ArGO), was collected and stored as a powder. To further control the pore structure of the powder by increasing the numbers of micropores and reducing the number of oxygen groups, 200 mg of ArGO powder was loaded onto a crucible and placed in a furnace under N2 conditions at 600 °C for 2 h, resulting in thermally treated ArGO (TArGO) powder. Because of the inert environment with N2 gas, the decomposition of the graphene powder was highly suppressed and the electrical conductivity of graphene was enhanced.GO powder (250 mg) was loaded in a quartz tube, which was spontaneously placed in a 650 °C furnace for 3 min under ambient conditions to reduce and expand the powder by rapid thermal annealing. This process is explosive due to the spontaneous gas emission by the decomposed oxygen-containing groups of GO, and thus, special care needs to be taken while handling large quantities of the powder. Long thermal annealing is not recommended here because the carbons of the graphene flakes can rapidly decompose in air at high temperatures2 adsorption–desorption isotherms were measured using a BELSORP-mini II (BEL Japan) and the Barrett–Hoyner–Halenda (BJH) method was used to calculate the pore size distribution. The electrical conductivity of the carbon materials was calculated from the sheet resistance of the graphene pellet, which was measured using the four-probe method with a Keithley 2635A SYSTEM SourceMeter. Graphene pellets with a thickness of 100 µm were prepared by pressing the graphene powder at 25 °C with a pressure of 2.6 ton/cm2. The sheet resistance of the graphene pellets was converted to electrical conductivity, as follows:The morphology of the obtained graphene product was observed using scanning electron microscopy , and X-ray diffraction (XRD) measurements were performed using an Ultima IV (Rigaku) instrument with a wavelength of 1.54 Å. Raman spectra were acquired using a Labram Aramis (Horriba Jovin Yvon) at an excitation wavelength of 532 nm. X-ray photoelectron spectroscopy (XPS) was performed using a K-alpha (Thermo U.K.) with a Cu(Kα) beam source (wavelength 1.5406 Å), and Fourier transform-infrared spectra were obtained using a Cary670 (Agilent) spectrometer. NHere σ is the electrical conductivity, Rs is the sheet resistance, and T is the thickness of the graphene pellets.2SO4 solution was used as the electrolyte. The specific capacitance (Csp) of the electrode was measured by galvanostatic charge and discharge (GCD) using the following equation:The electrochemical performances of rGO-V20 , ArGO, and TArGO were measured in three-electrode configurations using Biologic VSP as an electrochemical station. For fabricating the working electrode, a slurry was prepared by mixing 2.83 mg of graphene powder with 50 μL of 5 wt% Nafion binder in isopropyl alcohol (1.5 mL) and DI water (0.5 mL). The slurry was dropped onto a glassy carbon electrode and dried in a nitrogen chamber. A saturated calomel electrode was used as the reference electrode, while a platinum wire was used as the counter electrode; a 1 M H2/CO gas, which expands the graphene sheet to form a hierarchical structure with abundant slit nanopores  of 0.1, indicating the presence of micropores, while the N2 adsorption of GO was negligible due to the stacked structure and the absence of micropores. In addition, ArGO and TArGO showed type-IV adsorption isotherms in the relative pressure range of 0.4–1.0, indicating the presence of slit-like mesopores, as observed in the SEM images in Fig. 2 adsorption isotherm using the BJH model is also displayed in Fig. The Nles Fig. f. ArGO aThe external pore volume and surface area were obtained by subtracting the micropore volume and micropore surface area, respectively, from the total values.2/g of GO to 436.0 m2/g after the first rapid thermal annealing, and the specific surface area of TArGO further increased to 653.2 m2/g. When the specific surface area was divided into micropores and external pores, the surface area of the micropores increased from 115.2 to 367.2 m2/g, whereas that of external pores decreased from 320.8 to 286 m2/g after the second thermal annealing in N2. This tendency was also observed in the calculation of pore volume, showing increased total and micropore volume but decreased external pore volume after the second thermal annealing. This observation indicates that the second thermal annealing is effective in increasing the specific surface area by generating additional micropores, possibly due to the facilitated etching of carbon and oxygen from the basal plane of ArGO37. The surface values of TArGO surpassed those of the commercial rGO powder (V20-rGO) with values of 462 m2/g for the total surface area and 175.2 m2/g for the micro-surface area  over that of ArGO (320.8 m2/g) is attributable to the slightly enhanced stacking between the rGO nanosheets, as evidenced by the SEM image and XRD patterns of TArGO indicated above. In addition, we measured the rGO annealed in N2 at 600 °C for 2 h without rapid thermal annealing in the air , ArGO, and TArGO were tested as electrodes, as shown in Fig. 45. For comparison, the CV curves at a scan rate of 2–100 mV/s for V20-rGO and ArGO, as well as the GCD curves at constant current densities of 0.5–10.0 A/g for V20-rGO and ArGO, are summarized in Fig. Figure 47, the specific capacitance of TArGO improved drastically over those of ArGO and V20-rGO for all current density values; in particular, TArGO exhibited excellent performance up to 372.1 F/g at 0.5 A/g. Interestingly, TArGO exhibited higher specific capacitance than ArGO in the current density range of 0.5–3 A/g. However, it showed a lower specific capacitance than ArGO above a current density of 4 A/g. The transition of specific capacitance between ArGO and TArGO can be attributed to their pore structures, as reflected by the surface area shown in Table 2/g) than TArGO (286 m2/g), while TArGO was mainly composed of micropores with an extremely large micro-surface area of 367.2 m2/g, which originated during the second thermal annealing conducted under inert conditions; the micro-surface area was much larger than that of ArGO (115.2 m2/g). The total surface area with both external and micro-surfaces can be utilized for EDLC-type charge storage at lower current densities. Therefore, TArGO with a larger total surface area can exhibit better charge-storage performance at lower current densities. In contrast, during the fast-charging process at higher current densities, the micro-surface area became less effective and the charge-storage process mainly occurred on the external surface area and oxygen-containing groups  was stable and higher than that of previous carbon materials, which can be attributed to the hierarchical nanoporous graphene structure with partial oxygen groups, as summarized in the inset of Fig. 2SO4 in this experiment, and increase the capacitance by additional pseudocapacitance.The electrochemical performances of ArGO and TArGO were compared with those of previous carbon-based materials, as shown in Table 22 conditions to generate dense micropores on the basal plane of graphene while maintaining the hierarchical structure. A supercapacitor composed of TArGO showed a specific capacitance up to 372.1 F/g at 0.5 A/g and 280.0 F/g at 1 A/g in 1 M H2SO4 with excellent long-term stability even after 10,000 cycle tests. The excellent capacitance of TArGO can be attributed to EDLC, in addition to the slight contribution of the pseudocapacitance by the oxygen-containing groups. The suggested approach is not only effective for controlling the pore structure of graphene but is also highly scalable because of its simple process in the absence of additional chemicals.We demonstrated a simple yet effective method for preparing hierarchical nanoporous graphene using a dual thermal activation approach. First, rapid thermal annealing was introduced to generate a hierarchical pore structure by decomposing the oxygen-containing groups of GO. Then, the second thermal annealing was performed under NSupplementary Information


Livestock-associated (LA)-CC398-MRSA is closely related to pigs, being unfrequently detected in human invasive infections. CC398-MSSA is emerging in human invasive infections in some countries, but genetic and epidemiological characteristics are still scarcely reported.Staphylococcus aureus (SA) CC398, both MRSA and MSSA, among blood cultures SA isolates recovered in Spanish hospitals located in regions with different pig-farming densities (PD) and characterize the recovered isolates.To determine the prevalence of spa-types, and antibiotic resistance, virulence and human immune evasion cluster (IEC) genes were analyzed by PCR/sequencing.One thousand twenty-two SA isolates  recovered from blood cultures during 6–12 months in 17 Spanish hospitals (2018–2019) were studied. CC398 lineage identification, detection of spa-types were found among the CC398-MSSA isolates with t571 and t1451 the most frequent spa-types detected (75%). Most of CC398-MSSA isolates were Immune-Evasion-Cluster (IEC)-positive (88.6%), tetracycline-susceptible (95.5%) and erythromycin/clindamycin–inducible-resistant/erm(T)-positive (75%). No statistical significance was detected when the CC398-MSSA/MSSA rate was correlated to PD (pigs/km2) (p = 0.108). On the contrary, CC398-MRSA isolates were all IEC-negative, predominately spa-t011 (70%), and the CC398-MRSA/MRSA rate was significantly associated to PD (p < 0.005).Forty-four CC398-MSSA isolates  and 10 CC398-MRSA isolates  were detected. Eleven CC398-MSSA is an emerging clade in invasive infections in Spanish hospitals. CC398-MRSA (mostly t011) and CC398-MSSA (mostly t571 and t1451) show important differences, possibly suggesting divergent steps in host-adaptation evolutionary processes. While CC398-MRSA is livestock-associated (lacking IEC-system), CC398-MSSA seems to be mostly livestock-independent, carrying human-adaptation markers. S. aureus (MRSA) of clonal complex (CC) 398 has gained much attention during the past decade because, apart from colonizing farm-animals, it has become a frequent pathogen in humans mainly -but not always- in contact with livestock (S. aureus (MSSA) of lineage CC398 has been increasingly reported as a cause of invasive infections in patients without livestock contact in different European countries, mainly in France, but also in Portugal or Belgium (Livestock-associated (LA) methicillin-resistant ivestock . More re Belgium . Out of  Belgium . CC398-M Belgium .S. aureus (MSSA) CC398  is present in all types of IEC and is therefore considered a marker of this cluster  methicillin susceptible A) CC398 . This CCe system . The gen cluster . A subpo cluster . NeverthR), this is considered a marker for LA-CC398-MRSA detection among epidemiological or clinical strains (PD) of surrounding regions  were collected from blood cultures in 17 Spanish hospitals during 2018–19  . All 761 MSSA and the 25 MRSA-TETR isolates were included in this study.A total of 1,022  period) . In this2 ; Medium-PD (MPD): 10–50 pigs/km2 ; High-PD (HPD): 50–150 pigs/km2 ; Very-High-PD (VHPD): >150 pigs/km2   .S. aureus isolates obtained in the routine work of the microbiology laboratories as part of the diagnostic process, and no clinical data of patients was used.In this study we have analyzed the The resistance phenotype to eighteen antimicrobial agents was performed using automatic methods and/or disk diffusion tests. Breakpoints were considered according to the European Committee on Antimicrobial Susceptibility Testing and/or the Clinical and Laboratory Standards Institute, depending on hospitals.R isolates included in the study were subjected to specific PCR screening for CC398 lineage  eta, etb, tst, and lukF/S-PV gene screening.All 761 MSSA and 25 MRSA-TET lineage . spa-typisolates . Additioisolates : (1) ant2) and proportions of data of interest were studied. A p < 0.05 was considered statistically significant showing a relationship between the selected variables. These statistical analyses were performed using the RStudio program (version 1.2.5042).Spearman correlations between pig density (pigs/kmS. aureus isolates recovered from blood culture samples in the studied period (range: 9.1–52.6%). The lineage CC398 was detected in this multicenter study in 5.3% of total S. aureus isolates (including both MRSA and MSSA)  .n = 44) represented 4.3% of total S. aureus and 5.8% of MSSA invasive isolates (p = 0.108).The CC398-MSSA isolates detected (isolates . The disR isolates (40%) were ascribed to CC398 lineage, representing 3.8% of total MRSA and 1% of all S. aureus invasive isolates. All CC398-MRSA isolates were recovered from five hospitals located in regions with VHPD (p = 0.0023).Ten out of the 25 MRSA-TETith VHPD . A signispa-types were detected among the 44 CC398-MSSA isolates, being predominantly t571  and t1451 . The other spa-types detected were as follows: t011 (n = 2), t4030 (n = 2), t7880, t899, t034, t1255, and t7160 ; two novel spa-types were also found  (scn gene corresponded to the MSSA tetracycline susceptible (TETS) t011 isolates. One of the two CC398-MSSA/t011/scn-negative isolates was recovered in a hospital of a VHPD region and the patient was a pig farmer. The other t011 scn-negative isolate was from a hospital of a LPD region . Another CC398-MSSA isolate lacking the scn gene was TETR, ascribed to spa-type t034, eta-positive and was recovered in a hospital of a VHPD region. The remaining two CC398-MSSA scn-negative corresponded to isolates of spa-types t571 and t1451. In addition, the eta gene was detected in three other isolates: t571 (n = 1) and t1451 (n = 2), but neither etb nor lukF/S-PV were found in this study.Most of CC398-MSSA isolates (except five) contained the : 30.5%) . Two of erm(T) gene (75%), associated in all cases with the erythromycin-clindamycininducible (ERY-CLIInd) resistance phenotype (except in one t4030 isolate)  recovered in two hospitals located in a VHPD region.Most of the CC398-MSSA isolates carried the isolate) . This php = 0.574) or when correlation was analyzed for C398-MSSA [t571 + t1451]/MSSA and PD (p = 0.428).No statistical significance was detected when the CC398-MSSA-t571/MSSA rate was correlated to the PD of the surrounding regions (n = 7), t034 (n = 2), or t108 (n = 1). They were all multidrug-resistant, according to tet(M) and tet(K) genes, while methicillin-resistance was due to the mecA gene. They all lacked the scn gene or other virulence genes , and erm(C) or msr(A) genes (Four of the 25 MRSA-TETA) genes .spa-types were detected among our non-CC398/non-CC1 MRSA-TETR isolates: t1084, t1081, t148, t002, t1818, t2000, and t1597; they were mostly resistant to multiple antibiotics and scn-positive.Other tet(M) gene and presence of the erm(T) gene. Eight additional CC398-MSSA isolates carried the IEC system (human adaptation marker). This means that 39 of the 44 CC398-MSSA isolates (88.6%) carried the genes of the IEC system. On the contrary, all 10 CC398-MRSA isolates presented the characteristics of the LA clade  gene and absence of erm(T) gene).Staphylococcus aureus is a leading cause of bacteremia in Europe . CC398-MSSA has emerged as an invasive subpopulation particularly in France, and in other countries, with increasing prevalence reported over the years. The rate of CC398-MSSA with respect to S. aureus in this work (4.3%) is similar to the data previously detected by our research group in one Spanish hospital (5.2%)  ; it is sl (5.2%)  and lowel (5.2%) .p = 0.108), suggesting that CC398-MSSA is a livestock-independent clade. Severe infections caused by CC398-MSSA isolates, mostly acquired in the absence of animal contact were yet reported  support a previous study which demonstrated that increased pig population density in a region leaded to an increase in CC398-MRSA cases among hospitals of surrounding regions  and tet(M) genes, respectively) allows us to hypothesize about an evolutive stage in the human or animal adaptation. Resistance to ERY-CLIInd, mediated by erm(T) alone or combined with other genes is a recurrent characteristic among our CC398-MSSA isolates (75%), already reported in previous studies (Ind associated with the presence of the erm(T) gene may be a marker for CC398-MSSA detection.Most of our CC398-MSSA isolates harbored the IEC system (88.6%) which could suggest human adaptation and corroborates the livestock-independent origin. Nevertheless, some exceptions were detected; the absence of IEC system and the presence of a TET studies . TherefoR was demonstrated to be a good phenotypic marker (Ind with erm(T) gene, IEC-positive) and for CC398-MRSA (TETR-tet(M), IEC-negative). In our work, t571 and t1451 were the spa-types most frequent among CC398-MSSA isolates. Of note, t571 is the spa-type most associated with CC398-MSSA bloodstream infections in Europe (spa-type t1451 has been detected among both CC398-MRSA and CC398-MSSA isolates (scn gene (p = 0.574) or CC398-MSSA (t571 + t1451)/MSSA (p = 0.428).In the case of CC398-MRSA, TETc marker . Howevern Europe  and it iisolates , althougscn gene , but alln = 10) belonged to spa-types strongly related to livestock  were scn-negative and were recovered from hospitals of VHPD regions, pointing to an animal origin, being considered as LA-CC1-MRSA; the presence of IEC system and PVL genes in another t127/CC1 isolate suggest a probably human-adaptation. The CC1 is a community-associated clonal complex detected usually in humans, but the lineage t127/CC1 is also widely spread in livestock . Important differences were detected between CC398-MSSA and CC398-MRSA isolates suggesting two different clades, mostly livestock-independent and livestock-associated, respectively. CC398-MRSA isolates were exclusively found in hospitals located in VHPD regions (positive correlation to pig-farming density), and in all cases lacked scn gene, characteristic of animal origin. On another hand, CC398-MSSA are more frequently detected in blood cultures in the present study, and no statistical correlation was detected with the PD of the region in which hospitals were located. Resistance to ERY-CLIInd and presence of erm(T) gene could be good markers for livestock-independent CC398-MSSA isolates; moreover, contrary to CC398-MRSA, almost all were tetracycline-susceptible. The characteristics of MRSA and MSSA of CC398 should be further investigated to understand better their clinical and epidemiological burden in Spanish regions.The lineage CC398 was detected among 5.3% of The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation, to any qualified researcher.Ethical review and approval was not required for the study on characterization of bacterial isolates in accordance with the local legislation and institutional requirements.S. aureus CC398 designed and participated in the strain recovery, identification, and susceptibility testing. OM, LR-R, and MI-B performed the molecular characterization of isolates and susceptibility testing. SC realized the statistics analysis. CT, CA, MZ, and OM interpreted the results and performed the first writing of the manuscript. All authors reviewed and approved the manuscript.CT and CA conceived and designed the study. CA, EC, JMA, LL-C, CS, AL-C, AB-B, PB, MS, and the members of the Spanish Study group of clinical The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Moreover, the MSCs show outstanding cycling performance and remarkable flexibility over 10 000 charge–discharge cycles and 300 bending cycles. In addition, the capacitance and output voltage of the MSCs are easily adjustable through interconnection with well‐defined arrangements. The efficient, rapid manufacturing of the graphene‐based interdigital MSCs with outstanding flexibility, shape diversity, and high areal capacitance shows great potential in wearable and portable electronics.High performance, flexibility, safety, and robust integration for micro‐supercapacitors (MSCs) are of immense interest for the urgent demand for miniaturized, smart energy‐storage devices. However, repetitive photolithography processes in the fabrication of on‐chip electronic components including various photoresists, masks, and toxic etchants are often not well‐suited for industrial production. Here, a cost‐effective stamping strategy is developed for scalable and rapid preparation of graphene‐based planar MSCs. Combining stamps with desired shapes and highly conductive graphene inks, flexible MSCs with controlled structures are prepared on arbitrary substrates without any metal current collectors, additives, and polymer binders. The interdigitated MSC exhibits high areal capacitance up to 21.7 mF cm Highly flexible micro‐supercapacitors are manufactured on a large scale by a cost‐effective stamping strategy with highly conductive graphene inks. The efficient production of the flexible micro‐supercapacitor devices with outstanding shape diversity, high areal capacitance, and excellent cycling stability shows great potential for future applications in portable and wearable electronics. Moreover, the fixed shapes lead to inconvenient device connections and challenges in providing high capacitance and potential window requiring lots of conducting wires. Hence, conventional micro‐devices are hardly meeting the peculiar demands of high‐voltage electronics. Compared to conventional sandwich structures, planar MSCs with significant benefits such as long cycling life, fast rate capabilities, and superior power density have received tremendous interest as promising micro‐scale power sources for integrated electronic devices. More importantly, planar interdigital MSCs on‐chip with tailored sizes, designable shapes, superior flexibility, and space‐saving connections can potentially boost high‐voltage output.Miniaturized electronics, especially flexible, smart, portable, and wearable microelectronics, are urgently demanding lightweight and thin energy storage devices at low cost with high voltage, high energy density, and outstanding flexibility.1 Howe onion‐like carbon, activated carbon, and graphene) and pseudocapacitive materials , polypyrrole, and polyaniline), as thin‐film electrodes for supercapacitors (SCs). Among them, 2D materials  have been studied and used as electrodes for MSCs due to their ultra‐thin thickness, large surface area, and mechanical robustness and flexibility, allowing for ultrafast shuttling of electrolyte ions along the plane of 2D nanosheets. Through rapid and reversible adsorption/desorption, ions are stored at the electrode/electrolyte interfaces without chemical reactions, resulting in superior cycling stability and ultrahigh power density (>10 000 W kg−1). In addition, their flexibility and nontoxic and nonhazardous features could fulfill stringent requirements of wearable and portable electronic devices. As a result, planar graphene MSCs based on electric double layer capacitance have shown great potential for the electronic industry, offering a fast charge–discharge rate, high power density, and long cycling life with a planar architecture compatible with integrated electronic circuits.To date, numerous efforts have been employed to explore novel electrode materials, including carbon‐based materials . Furthermore, the metal current collectors and interconnects lead to reduced volumetric and gravimetric capacitances, and ungratified flexibility of MSCs. A detailed comparison of the differences of the various techniques is shown in Table S1, Supporting Information. Therefore, several key challenges remain in the rational engineering of planar MSC devices, such as: 1) developing novel electrode materials (including current collectors) with outstanding energy and excellent flexibility; 2) exploring new electrolytes with broad voltage window for promoting energy density; and 3) simplifying the fabrication processes.The fabrication of electrode‐patterned MSC devices often contains complex lithography processes , high‐pressure pressing, O Cr, Au).16 Fur−1), remarkable mechanical flexibility, and strong adhesion with the cellulose paper. Both the manufacturing time and cost of the stamping strategy to fabricate graphene‐based MSCs are radically reduced compared to those of 3D printing and photolithography, which generally need certain requirements of the substrate or heavily rely on precision equipment. The graphene‐based MSCs display a high areal capacitance (C/A) of 21.7 mF cm−2, an outstanding cycling stability with 98.8% retention after 10 000 charge–discharge cycles, an energy density of 5 µWh cm−2 at a power density of 6 mW cm−2, and robust mechanical flexibility without any apparent degradation under various deformed states. It is worth noting that the stamping strategy is feasible for mass production of multiple flexible graphene‐based MSCs to regulate the capacitance and output voltage for integrated electronics.Here, we report a low‐cost and facile stamping approach to fabricate flexible planar MSCs using porous graphene inks. The resulting planar devices are free of metal current collectors, polymer binders, and separators. Notably, the stamped devices exhibited excellent uniformity, good electrical conductivity  strategy was applied to synthesize porous graphene nanosheets. By utilizing a porous hexagonal MgO template, the porous graphene with good structural stability could be grown via CVD with several graphene layers, hexagonal morphologies, and large surface area. The fabrication strategy could be readily scaled up to achieve large‐scale preparation of the graphene with well‐defined structures. Because of its novel porous nanostructure and ultrahigh surface area, the porous graphene has an outstanding energy storage capability.Figure ID/IG) of the porous graphene is around 2, indicating a high density of defects of the template‐assisted CVD‐grown graphene. The powder X‐ray diffraction (XRD) patterns in Figure S2, Supporting Information, show crystalline structures of the MgO@graphene and porous graphene. The diffraction peaks observed at 36.9°, 42.9°, 62.3°, 74.6°, and 78.6° are assigned to the (111), (200), (220), (311), and (222) planes of MgO (JCPDS card no. 78‐0430). After acid etching, all the diffraction peaks of MgO disappeared ; the graphene peak is dramatically broadened and of less intensity, indicating the presence of a high density of pores in the porous graphene sheets.The structure and morphology of as‐prepared graphene are characterized in 2 g−1), much higher than that of MgO@graphene (140 m2 g−1). Furthermore, the distribution of pore sizes indicates a mesoporous feature with pore sizes in the range of 3−20 nm. The highly porous structure, high BET surface area, and wide pore size distribution can provide efficient transport paths as well as abundant active sites for electrons and ions, resulting in a better contact with electrolyte and therefore accelerating the ion transfer during the charge–discharge process. The graphene sample was further investigated by X‐ray photoelectron spectroscopy (XPS) that confirms the complete removal of the template. The XPS survey spectrum  exhibits predominantly the C 1s peak from graphene and no traces of metal species are detected. Figure π–π* shake‐up satellite peak (291.0 eV), respectively. Transmission electron microscopy (TEM) images in Figure 2 adsorption–desorption results.The nitrogen adsorption–desorption isotherms as well as the corresponding pore size distribution of the MgO@graphene and porous graphene are shown in Figure S3, Supporting Information, and Figure 2 . The excellent electrical conductivity ensures rapid electron transport, resulting in high energy and power density of the porous graphene electrodes.For electronic applications, the porous graphene can be provided in dispersions or inks to prepare large‐area graphene conductive films on glass substrates. The porous graphene was pasted and pressed to form a flexible, continuous graphene film (≈50 µm in thickness) on transparent glass substrates . The van der Pauw measurement technique was performed to evaluate the electrical conductivity of the graphene film . The current, voltage, and the corresponding resistances of the graphene film are recorded in Table S2, Supporting Information, respectively. The calculated sheet resistance of the graphene film is around 1.18 Ω m−1 with a potential window of 0–0.8 V. It is clearly seen that the CV curves exhibit nearly rectangle shapes even at a high scan rate of 1000 mV s−1, and galvanostatic charge–discharge (GCD) curves show symmetric triangle shapes and negligible voltage drops, suggesting an ideal electric double layer capacitive feature. We further tested the electrical properties within a potential window of −0.6 to 0 V. The CV and GCD curves also show rectangle shapes and symmetric triangle shapes. The electrode displays a specific capacitance of 130 F g−1 at 1 mA with both positive and negative potential windows, suggesting outstanding capacitive properties, remarkable reversibility, and a broad operation potential window. The long‐term cycling stability of the porous graphene electrode was further investigated by GCD tests at 5 mA within a potential window of 0–0.8 V and −0.6 to 0 V. The cycling curves in Figure S9, Supporting Information, demonstrate that 98.5% and 98.9% retention of the capacitance are maintained after 5000 cycles within these two potential windows, showing outstanding cycling stability. The shapes of the last 10 GCD curves are maintained well after 5000 cycles . In addition, the very small voltage drops further demonstrate the excellent electrochemical reversibility.The electrochemical property of the porous graphene electrode was studied in a three‐electrode system in 6 M KOH electrolyte . Figure S8a,b, Supporting Information, show the cyclic voltammogram (CV) curves tested at various scan rates from 25 to 1000 mV sFigure 2 and the thickness is around 20 µm. The electrode size parameters of the interdigital MSC are shown in Figure S11, Supporting Information. Figure −1 within different potential windows. A maximum potential window of 0–1.5 V was employed, beyond which the CV curves show distorted features, indicating irreversible reactions on the electrode surface. Hence, a potential voltage of 0–1.4 V was used as the safe and optimal operating voltage for the MSCs. The electrochemical performance of the stamping MSCs was evaluated by CV and GCD measurements in Figure −1, and display a linear dependence of the maximum current density with scan rates, manifesting high electrochemical reversibility and high‐power capability. The absence of redox peaks indicates a double‐layer capacitive behavior of the graphene‐based electrodes. The GCD curves of the graphene‐based interdigital MSC  of the original value measured at 0.43 mA cm−2. The volumetric capacitance is calculated to be 10.9 F cm−3 at a current density of 0.22 A cm−3 for the interdigital electrode. The rate capability of the graphene‐based interdigital MSC is shown in Figure −1) and large surface area (2326 m2 g−1) of the active materials.The porous graphene ink was stamped onto a piece of cellulose paper to form symmetric MSCs in which PVA/KOH gel electrolyte was employed to seal the patterned electrodes Figure 3a. The sC Figure  exhibit −2 at a power density of 0.3 mW cm−2, corresponding to a volumetric energy density of 2.95 mWh cm−3 at a volumetric power density of 149 mW cm−3. The maximum areal power density is 6.0 mW cm−2 at an energy density of 5.0 µWh cm−2, corresponding to a volumetric power density of 3.0 W cm−3 at a volumetric energy density of 2.5 mWh cm−3. Table S4, Supporting Information, shows the detailed comparison of the voltage window, capacitance, cycling life, energy, and power density of recently reported graphene‐based MSCs, among which our device shows superior electrochemical performance compared to most of these works.Energy densities and power densities are essential parameters to evaluate the performance of energy storage devices. The Ragone plot in Figure se works.17+) into the electrode materials during the electrochemical tests . The K2p spectra were collected during XPS depth profiling  from both sides of the electrode , clearly revealing the homogeneous penetration of K+ through the whole electrode. The calculated atomic ratio of K/C does not show any significant change versus depth, further indicating the good contact with the electrolyte and efficient transport paths of the electrolyte ions in the electrode materials during the electrochemical process. Meanwhile, the SEM image of the porous graphene after 10 000 cycles  suggests that the porous structure is maintained very well.The long‐term cycling property of our device was evaluated by GCD tests at 5 mA within an operating voltage from 0 to 1.4 V Figure . The arex‐axis, which shows a slight increase from 264.2 to 281.6 Ω after 10 000 cycles, suggesting superior conductivity of the electrolyte and the small internal resistance of the electrodes. More detailed results of the Rct and Rs of the graphene‐based MSC after cycling are recorded in Table S3, Supporting Information.The electrochemical resistance was further evaluated by electrochemical impedance spectroscopy (EIS) measured after different charge–discharge cycles. In the high‐frequency regions of the Nyquist plot in Figure r) (or bending curvature 1/r) are used to characterize the mechanical properties : 1.5 V). Figure 3−1), and large surface area (2326 m2 g−1) of the active materials. A high areal capacitance up to 21.7 mF cm−2 was obtained at a current of 0.5 mA. Notably, the devices exhibit remarkable cycling stability and remarkable flexibility over 10 000 charge–discharge cycles and 300 bending cycles (with a bending radius of 1 cm and bending angle of 180°). In addition, the output voltage and capacitance of the MSCs are easily adjustable through interconnection with well‐defined arrangements. Therefore, the efficient production of the flexible graphene‐based MSCs with outstanding flexibility, shape diversity, and high areal capacitance shows great potential for future applications in portable and wearable electronics.In summary, a highly flexible graphene‐based MSC was manufactured by a cost‐effective stamping strategy without metal current collectors, binders, or additives. The interdigitated MSC exhibits remarkable electrochemical performance owing to the rational design of the device, high electrical conductivity  powder was loaded in a alumina boat, which was then transferred to a clean quartz tube in the CVD system. The system was first pumped down to a base pressure of around 0.2 mTorr, followed by two purges in pure Ar, and then 50 sccm of Ar was introduced to the system to achieve a pressure of 200 Torr. The CVD system was gradually heated to 1030 °C for 1 h and maintained for another hour and then the Ar flow was switched off and a mixed flow of CH4 (50 sccm) and H2 (30 sccm) was introduced into the system for the graphene growth for 1.5 h. After growth, CH4 and H2 gas were switched off and Ar was switched on and the system was quickly cooled down to a room temperature.The magnesium hydrate (Mg(OH)m) and followed by a constant stirring at a hot plate of 80 °C for 24 h to remove the MgO template. The porous graphene was collected by filtration, washed with deionized water several times, and freeze‐dried.The as‐obtained MgO@graphene sample was dispersed in aqueous HCl solution  to remove unexposed polymer. Finally, the SU‐8 stamps were treated by oxygen plasma for 10 min prior to the stamping process to increase the hydrophilicity. The thickness of the SU‐8 frame was around 1 mm.Typically, the graphene ink was brushed onto the interdigitated fingers of stamp. Then the stamp was firmly pressed onto a piece of cellulose paper. After 3 s, the stamp was removed and the MSC was dried naturally. The stamping process was repeated three times. Other MSCs, such as “TUC” pattern, were stamped by stamping the graphene ink in a similar way. In addition, graphene ink was also stamped onto a leaf. All the MSCs were vacuum‐dried overnight before tests.The crystallographic information and chemical composition of the samples were characterized by XRD  and XPS . The morphology and microstructure of the products were investigated by SEM (ZEISS Auriga) and TEM (ZEISS LIBRA 200). Nitrogen adsorption–desorption isotherms were measured at 77 K with a Micromeritics ASAP 2020 sorptometer. Raman analysis was performed via a Raman spectrometer  at room temperature.m PVA/KOH, 1 m PVA/H2SO4, and 1 m PVA/Na2SO4 gel electrolyte.The electrochemical tests including CV, GCD, and EIS of the MSCs were measured using an electrochemical workstation (autolabIII/FRA2) in 6 C) of the samples can be calculated from both the GCD and CV curves based on the following equationsA, I, ∆t, ∆V, µ, V1, and V2 are the footprint areal (cm2)/volume (cm3) of the electrodes, discharge current (mA), the discharging time (s), the discharging potential range (V), the scan rate, high‐voltage value, and low‐voltage value, respectively.The areal/volumetric specific capacitances  and power density  of the devices were calculated using the following equationsEnergy density (The authors declare no conflict of interest.Supporting InformationClick here for additional data file.


The calculated gas phase ΔacidG° values obtained were close to the experimental ones reported in the literature. The good relationship between the ΔacidG° values and the electronegativity of ZC6H4COOH and its fragments, suggested a better importance of the inductive than polarizability contributions. The balance of inductive and resonance contributions of the substituent in the acidity of substituted benzoic acids showed that the highest inductive and resonance effects were for the -SO2CF3 and -NH2 substituents in the para- and ortho-position, respectively. The Fukui function confirmed that the electron-releasing substituent attached to the phenyl ring of benzoic acid decreased the acidity in the trend ortho > meta > para, and the electron-withdrawing substituent increased the acidity in the trend ortho < meta < para.A theoretical study of the effect of the substituent Z on the gas phase acidity of substituted benzoic acids ZC KaX/logKaH = σρ) is a linear Gibbs free energy relationship (a link between equilibrium constant and reaction rates) that uses the properties of substituted benzoic acids as a reference standard to study the effect of substituent on the reactivity and properties of various molecules  calculations, they found a good correlations with the Löwdin, Mulliken, AIM, and natural population analysis charges on atoms of the dissociating carboxylic acid group. Méndez et al. studied the effect of substituent on the acidity and reactivity of para-substituted phenols [The Hammett equation . We found that there is a good relationship between the acidity of substituted benzoic acids and the electronegativity of ZC6H4, ZC6H4COO and ZC6H4COOH indicating the importance of the inductive contributions. While for the softness of ZC6H4COOH and its fragments there is not a relationship with the acidity, suggesting less importance of the polarizability contributions. The Fukui function, a density functional theory (DFT) descriptor related with the resonance effect [1a–3c) decreases the acidity in the trend ortho > meta > para, and the electron-withdrawing substituent (4a–6c) increases the acidity in the trend ortho < meta < para.Most of the previous studies have evaluated the acidity of the H 1a–6c,  in terms1a–6c, χ  and softectively ,26,27,28e effect ,29, show1a–6c, they were obtained as ΔacidG° = G°(anion) + G°(H+) − G°(acid). The calculated ΔacidG° values were close to the experimental values reported in the literature  and SO2CF3 (compounds 6a–6c) the least and most acidic, respectively; they correspond to the two extremes for which δΔacidG° = 19.37 kcal/mol. Interesting for the electron-releasing substituent attached to the phenyl ring the acidity follows the trend ortho > meta > para, and the average value for the two extremes is δΔacidG° = 3.7 kcal/mol, while for electron-withdrawing substituent the acidity follows the trend ortho < meta < para, and the average value for the two extremes is δΔacidG° = 2.4 kcal/mol.The calculated gas phase acidity values are consistent with the substituent electronic effect, being the benzoic acid with substituent NHacidG° = mx + b, where x is the electronegativity χ or softness S of Z, C6H4, ZC6H4, ZC6H4COO and ZC6H4COOH , respectively, where μ = − (I + A)/2 = −χ and η = (I−A)/2, where I is the ionization potential and A the electron affinity [6H4, ZC6H4 and ZC6H4COO were obtained using the condensed Fukui function for each fragment and the Hirshfeld charges analysis [Considering that the steric effects are of limited importance for acidity  and the ivatives , while fivatives ). The elaffinity . The eleanalysis ,33.Sfragment and ΔacidG°, the poor correlation coefficient values obtained shows that there is not direct relationship between ΔacidG°, and the softness of Z, ZC6H4, ZC6H4COO and ZC6H4COOH. The nonlinearity suggesting that the polarizability contribution has not an important role in the acidity of substituted benzoic acids. Instead, χfragment and ΔacidG° for ZC6H4, ZC6H4COO and ZC6H4COOH. The acidity of the substituted benzoic acids increases when the electronegativity of the fragments ZC6H4, ZC6H4COO increases. The nonlinearity between the electronegativity of the substituent Z and ΔacidG° suggesting that there is no direct interaction between the substituent and the hydrogen atom of the carboxylic group. Therefore, the substituent Z transmits its inductive effect through the π system of the benzene ring C6H4 and the hydrogen atom of the carboxylic group shows the effect of the electronegativity of the whole fragment ZC6H4COO. This is consistent with the good relationship obtained between the hydrogen charge and the ΔacidG°  will increase the acidity of the benzoic acid in the trend ortho- > meta- > para-position.We have shown previously that the resonance hybrid structure can be described in terms of the Fukui function ,29. The /δν)/∂N) . The chaectively . Thereforinciple  they wil4a–6c) we examined the Fukui function for nucleophilic attack 4a–6c. As the substituent changes its position from ortho to para, the contribution of the C-2 atom increases. The C-2 atom will increase its reactivity because in the electronic redistribution it is suitable to gain electron to a nucleophile and according with the local HSAB principle [3, NO2 and CF3SO2) will increase the acidity of the benzoic acid in the trend para- > meta- > ortho-position.For the benzoic acid with the electron-withdrawing substituents (rinciple  it will ortho) = ΔacidG°ortho(-CH3) − ΔacidG°ortho(-SO2CF3), IE(meta) = ΔacidG°meta(-CH3) − ΔacidG°meta(-SO2CF3), IE(para)ΔacidG°para(-CH3) − ΔacidG°para(-SO2CF3), RE(CH3)= ΔacidG°para(-CH3) − ΔacidG°ortho(-CH3), …, RE(-SO2CF3) = ΔacidG°ortho(-SO2CF3) − ΔacidG°para(-SO2CF3). With the calculated absolute gas phase acidity  of the substituent can be approximated as the difference of the gas phase acidity values between the two extremes: IE level of theory using GAUSSIAN09 [acidG° was obtained using ΔacidG° = G°(anion) + G°(H+) − G°(acid). The Gibbs free energy of the proton in the gas phase G°(H+) = −6.26 kcal/mol was obtained by means of partition functions using statistical thermodynamic relationships [1a–6c were visualized by the gOpenmol software [ortho-amino substituent with the O=C-O-H dihedral near to 180° was 322.51 kcal/mol and for 0° was 331.04 kcal/mol, respectively; the experimental value is 330.31 ± 2.01 kcal/mol. The conformational analysis showed no disagreement in the DFT descriptors due to the change of the dihedral angle O=C-O-H from 0 to 180 degrees; we observed that the linear relations of free energy between acidity and the DFT descriptors do not depend on the conformational peculiarities of this molecule. We compared the electrophilic and nucleophilic Parr function [ortho-, meta- and para-substituted benzoic acids 1a–6c and we obtained not difference with the Yang and Mortier Fukui functions.The ground state structures, energies and gas phase acidities of the USSIAN09 . Please ionships . All of software . Frequenfunction  for the ortho-, meta and para-substituted benzoic acids. The analysis of inductive and resonance effects of the substituent in the acidity of substituted benzoic acids shows that they contribute in the opposite way, for electron-withdrawing substituent the acidity increases from ortho- to para-isomers when the inductive and resonance effects increases and decreases, respectively, while for electron-releasing substituent the acidity increases from para- to ortho-isomers when the inductive and resonance effects decreases and increases, respectively. The highest inductive and resonance effects are for the -SO2CF3 (electron-withdrawing) and -NH2 (electron-releasing) substituents in the para- and ortho-position, respectively. The acidity difference between the para-SO2CF3 and ortho-NH2 benzoic acids is 14.16 kcal/mol. Recently, Georgousaki et al. [p-hydroxybenzoic acid can be considered as a promising candidate for the development of novel modulators of the proteostasis network, and likely of anti-aging agents. They showed that benzoic acid derivatives substituted with OH, CH3 and Cl enhance the activity of the two main cell protein degradation systems (the ubiquitin-proteasome and the autophagy-lysosome pathway) and especially the activity of cathepsins B and L. We hope that our results will open up the possibility of analyzing the chemical-biological interactions of substituted benzoic acids in terms of DFT reactivity descriptors.The electronegativity and the Fukui function are good descriptors to account for substituent effects in the gas phase acidity of a set of i et al.  have poi


In addition, a USP apparatus 2 with enhancer cells was utilized to study the in vitro drug release characteristics of the selected formulations. All the ointments obtained were characterized by good spreadability and viscosity. An analysis of the ointment texture was performed and the dependence of the tested parameters on the ACTH content in the ointment was demonstrated. Examination of the structure of the ointment showed that a high concentration of ACTH increases the hardness and adhesiveness of the ointment. In turn, it adversely affects the cohesiveness and elasticity of the ointments tested. The results of the release study showed that ACTH is released the fastest from the formulation with the lowest concentration, while the slowest from the ointment with the highest concentration of ACTH.Corticotropin  is used in the diagnosis and treatment of pituitary gland disorders, adrenal cortex disorders, and other diseases, including autoimmune polymyositis, systemic lupus erythematosus, rheumatoid arthritis, Crohn’s disease, and ulcerative colitis. So far, the ointment dosage form containing ACTH for use on the skin is unknown. Therefore, it seems appropriate to develop a semi-solid formulation with corticotropin. Emulsion ointments were prepared using an Unguator based on the cream base Lekobaza Similar results were obtained by Szulc-Musioł et al., who found an inverse correlation between the spreading rate and quercetin content   represents the force applied to the ointment, A [m2] displays the calculated cross-sectional area of the ointment cylinder, Δl [m] represents the length deformation, and l [m] represents the original sample length. Young’s modulus is a measure of the “stiffness”  of a material, the material’s ability to rebuild its original shape after deformation  was calculated per unit of time, and the profiles of its cumulative release were drawn.A modified USP Apparatus 2 equipped with 200-mL flat-bottom vessels and mini paddles  was used for the drug release studies. An excess amount of the ACTH ointment was loaded inside a special semisolid holder, Enhancer fluoropolymer cells  with an exposed area of 3.8 cmp < 0.05 was calculated using Student’s t-test.Mean values with standard deviation were calculated and statistically analyzed using the Microsoft Excel package  and Statistica  option: Industrial analysis, experimental design (DOE). The Statistica Pharmaceutical Kit: Statistica “Release Profiles” was used to analyze the results of ACTH release from the ointment bases, with the Weibull method. Statistical significance at An innovative topical ointment formulation of the drug for use on skin containing the hormone corticotropin was obtained and tested. After studies of the physicochemical properties and release, potential benefits were found after both low and high concentrations of ACTH.The physicochemical properties of the tested ointment formulations are influenced by both the introduction of aqueous solution into the ointment bases and the addition and content of active substance. The addition of aqueous solution improves the spreadability of the ointment and thus enables easy application of the preparation on the skin surface. It allows administration of the ointment in very small quantities (dosages) and reduces systemic toxic effects. Aqueous solution added to the obtained preparations reduces the viscosity, hardness, adhesiveness, elasticity, and mechanical resistance of the ointment to tensile stress. The tested formulations showed smaller thixotropy at a temperature of 32 °C than at 25 °C.A low concentration of ACTH (5 mg/g) did not significantly affect the texture parameters, while the high concentration of ACTH (20 mg/g) increased the viscosity, hardness, adhesiveness, and tensile strength of the ointment, which in turn adversely affects the cohesiveness and elasticity of the tested ointments and, consequently, makes it difficult to spread the preparation on the skin.The acetic acid content in the aqueous phase lowers the pH of the ointment, and corticotropin slightly contributes to the increase of the pH value, the higher its concentration in the ointment.Based on the release test, it can be found that the ACTH release rate depends on its concentration in the ointment. Within the tested concentration range, the release process occurred the fastest from the ointment with the lowest ACTH concentration (15 mg/g), whereas after applying the concentration of 25 mg/g, a prolonged effect can be expected, which may be beneficial in the case of drugs with a short half-life, such as ACTH (5–15 min). The rate of corticotropin release depends on the viscosity and hardness of the ointment. The lower the viscosity and hardness of the ointment formulations, the faster the release of ACTH. As the temperature increases from 25 to 32 °C, the viscosity decreases slightly, which may be beneficial during application of the preparation on the skin.


ION/IOFF of 106 obtained from the transfer curves and adjustable intrinsic gain up to 4, and exhibits unprecedented current stability in temperature range of 15–400 K. The vertical device operation can be optimized with the capacitive coupling in the device geometry. The semiconductor-less switching resolves the long-standing issue of temperature-dependent device performance, thereby extending the potential of 2D van der Waals devices to applications in extreme environments.Semiconductors have long been perceived as a prerequisite for solid-state transistors. Although switching principles for nanometer-scale devices have emerged based on the deployment of two-dimensional (2D) van der Waals heterostructures, tunneling and ballistic currents through short channels are difficult to control, and semiconducting channel materials remain indispensable for practical switching. In this study, we report a semiconductor-less solid-state electronic device that exhibits an industry-applicable switching of the ballistic current. This device modulates the field emission barrier height across the graphene-hexagonal boron nitride interface with  6.In field-effect transistors, a semiconducting channel is indispensable for device switching. Here, the authors demonstrate semiconductor-less switching via modulation of the field emission barrier height across a graphene-hBN interface with ON/OFF ratio of 10 With the rapid development of the semiconductor industry, conventional three-dimensional (3D) semiconductors  are encountering challenges in terms of increasing further spatial resolution of the device and temperature-dependent device performances in various environments. The enhanced electric field degrades the carrier mobility in the semiconductor channel. It is because, with the enhanced electric field, the carrier starts to scatter with optical phonon of the semiconductors and lose more of its energy, resulting in the velocity saturation1. Also, the carrier density or device performance depends on the temperature and, as a result, deviates from Moore’s law3. To overcome the first challenge, vacuum-channeled devices (vacuum field-effect transistors), which resemble the primitive vacuum tube triode of the early 1900s, have attracted enormous interest because they utilize ballistic transport by tunneling through the vacuum channel4, and recently, they demonstrate the long-term stability processability in 150-mm water scale5. However, industry-applicable current switching was not realized in the tunneling devices, and the source  and gate  currents continue to rely on thermally generated carriers, which retain most of the drawbacks associated with conventional semiconductor devices.Semiconductors have been indispensable to solid-state electronic devices since the first solid-state electronic device  because the channel current of the transistor must be modulated by the carrier (electron and hole) density, which relies on the bandgap of the semiconductors9. Despite its unprecedentedly high room temperature mobility10, the graphene FET (GFET) still suffers from insufficient switching (ION/IOFF ~ 10 at room temperature) because of the absence of a bandgap11. Additionally, we know that artificial bandgap opening in graphene inevitably sacrifices the mobility12. In contrast, transition metal dichalcogenide-based FETs have shown ION/IOFF values of up to 108 using their bandgaps, but their carrier mobilities remain at ~20% of that of Si7. These inherent limitations can be resolved by using vertical van der Waals heterostructures and work function modulation of graphene as a switching principle13. This principle was originally demonstrated in graphene barristors (GBs)14 and has been used in various devices containing either organic18 or inorganic25 semiconductor–graphene junctions. In addition, bipolar junction transistor-like devices have been also investigated, where graphene was used as a base material, thus called as graphene-base transistor30. The switching in such devices does not rely on the thermally generated charge of semiconductors, but semiconductors are still crucial elements required to achieve efficient switching. Thus these 2D devices have the same limitations as conventional semiconductor devices: scattering-limited carrier mobility and temperature-dependent device performance.As an alternative, two-dimensional (2D) vertical device structures have been proposedION/IOFF has been reported31. To control ballistic transport adequately, we considered two modes by which current can tunnel through either vacuum or insulator channels: (1) direct tunneling (DT), which most graphene tunneling devices (including ref. 31) use for switching, and (2) field emission (FE), which has been rarely explored. The DT is proportional to the density of states (DOS) of two electrodes, whereas the FE is exponentially influenced by the tunneling barrier height32. When the electric field modulates the charges on graphene, both the work function and DOS at the Fermi level of the graphene are modulated. However, the two tunneling-current modes behave differently under modulation. Although the DT current produces physically limited insufficient switching  via the DOS modulation of graphene33, the FE current can be largely modulated by an exponential function of the barrier height.The ideal solution  has not yet been realized; indeed, only one-order modulation of hBN)–graphene–hBN–metal , tunneling-channel capacitance (CTC), and quantum capacitance of graphene (CQ) in the FEB. Consequently, the above coupling effect is universal in all 2D vertical device geometries, which implies that the optimization principle can be applied to other vertical devices to improve their performance.Here we report a semiconductor-less electronic device based on a van der Waals vertical heterostructure of metal–hexagonal boron nitride  of 62 nm and a tunneling-hBN thickness (tTC) of 64 nm shows an efficient switching (by an ION/IOFF of up to 106) without semiconductors. The channel current (ID) increases exponentially by an increase of the gate bias (VG). As the VG increases, more electrons are accumulated on the graphene, which decreases the work function of graphene by the square root of the electron density and the tunneling barrier height (ΦB) for the “on” state. The FE current ID, which increases exponentially as the ΦB decreases, can be described as follows35:Aeff is the effective tunneling area, q is the elementary charge, m is the mass of electron or hole, m* is the tunneling effective mass, V is the applied voltage, h is Plank’s constant, and d is the tunneling distance. While the Schottky current depends on the temperature, the FE current barely depends on the temperature36. The above formula supports the critical device operation, the switching with an ION/IOFF ratio of ~106, presented in Fig. ION/IOFF ratios of ~10, which is a physical limit imposed by the fact that the charge density modulation is limited to 100 at room temperature37. As VG increases, the tunneling mechanism of the electrons for the gate leakage current is changed from DT to FE at VG = 14 V or a gate field of 0.23 V/nm in a similar manner with ID. The IG remains <0.5% of ID in the VG range. Minimizing the leakage effect on the ID, the gate field was limited to 0.23 V/nm in our study.In Fig. ID) exhibits little variation at temperatures of 15–400 K under various operating conditions. This independence is attributable to the nature of the FE tunneling. Notably, the current does not degrade even at T = 15 K, at which the charge carriers of most semiconductors would be frozen2. The absence of degradation is a characteristic feature of our semiconductor-less ballistic device.A critical issue affecting semiconductor-based devices—i.e., temperature-limited operation—can be resolved by our semiconductor-less ballistic device. Figure VD). First, ineffective gating (ION/IOFF ~ 10) appears in the DT regime at low VD, whereas effective gating (ION/IOFF > 104) is activated at high VD. The increase in the drain voltage converts the channel current from DT to FE, allowing the modulation of the FE current shown in Fig. VD and negative VD decrease from 27 V (VG = −5 V) to 13 V (VG = 10 V) and from −19 V (VG = 5 V) to −8 V (VG = −10 V), respectively; thus a higher VG realizes a lower ΦB.The channel current in Fig. ID/VD2) = α + β/VD, where α and β have relevance to the charge density and tunneling energy barrier, respectively. Thus the linearity between ln(ID/VD2) and 1/VD confirms the FN tunneling38. By assuming that the graphene is a single emitter, α and β were uniquely determined, as follows. The barrier height was obtained from the modified FE equation: α and β are β was obtained by replotting the output characteristic of a FEB according to the modified FE equation. β includes a parameter of the FE barrier height. Therefore, β declined with increasing VG and the FE barrier height decreased from 2.01 eV to 1.84 eV with increasing VG from 2 V to 8 V, as exhibited in Fig. The FN equation can be formulated as ln, cut-off frequency (fT), and power-delay product (PDP)—of the semiconductor-less FEBs were investigated by varying tGate and tTC, where τ is a time delay required to charge gate electrode with ION, fT is a figure of merit of analog transistors in terms of switching speed, and PDP is that of digital ones in terms of required energy for switching40. The tGate and tTC affect the amplitude of the graphene work function modulation, tunneling-barrier height, and thus device performances. First, the capacitive coupling governs how effectively the VG accumulates charges in the graphene as observed in GFET. The capacitive coupling or quantum capacitance (CQ) of the graphene in the GFET has been determined to reduce the work function modulation because the CQ is serially connected to the gate capacitance CGate  multiplied by the VG, where the larger the CGate, the higher the effect of CQ, resulting in the smaller accumulated charge on the graphene42. However, the FEB involves a more complex network of capacitors because of the additional tunneling-channel capacitor (CTC), as shown in Fig. φgr) in the FEB is determined by the following equation :Qfic) on graphene accumulated by varying both the operating conditions (VG and VD) and the device structures (CGate and CTC); the right side demonstrates how the Qfic determines φgr with the coupling of CGate and CTC. Both the CTC and CGate govern the work function shift in an identical manner  also exist in the Si substrate. Their turn-on state was achieved when the minority charge accumulated on the channel, resulting in inversion. In the inversion state, CBody has no role in the capacitive coupling. Therefore, CGate is the most critical capacitance, and we are less concerned about capacitive coupling.). The work function shifts with the accumulated charge and can be obtained for the GFET and FEB by varying the Ctotal = CTC + CGate, as shown in Fig. Ctotal produces a larger work function modulations of graphene by the same amount of charges (x-axis). Therefore, the minimum value of the Ctotal should be targeted to improve the ION/IOFF, and the upper limit of the shift with a fixed CGate can be determined when the CTC becomes 0 . The above coupling analysis is generally applicable to other vertical devices, including field-effect tunneling transistors, vertical field-effect transistors (vFETs), thin-film barristors, and GBs, that rely on the work function modulation of graphene, as shown in Supplementary Fig. Device characteristics—work function modulation of graphene, intrinsic gain, ate Fig.  and, conmentclass2pt{minimgm) to drain conductance (gds)12, is proportional to the CGate–CTC ratio (tTC–tGate ratio), as shown in Fig. 13, there is some doubt that the devices could not amplify (intrinsic gain <1). However, we obtained the gains of 2.5 and 3.6 using FEBs with the CGate–CTC ratios of 2.0 and 3.9, respectively. Along with the other 4 FEBs, we clarified that the intrinsic gain is proportional to the CGate–CTC ratio, as exhibited in Fig. VG and VD by a coupling between the CGate and CTC, described in the above equations.Second, the intrinsic gain of FEB, obtained by the ratio of transconductance : ION increases from 0.87 mA/cm2 to 1.59 A/cm2; the τ decreases from 0.7 ms to 0.52 μs; fT increases from 0.21 kHz to 0.59 MHz. It is because the ION exponentially depends on the barrier height at the graphene–hBN junction, which decreases with tTC, as shown in Fig. hBN is obtained as 3.2 eV using single-emitter approximation; that of 301-nm thick one decreased to 2.1 eV. It is common for electron affinity of 2D materials to decrease with their thickness43. Therefore, they can improve the device performances by increasing the tTC. However, the thicker the tTC, the greater is the VD required for field emission from the graphene to the drain electrodes. It is why the PDP increases(or worsens) as the tTC increases: as the tTC increases from 19.5 to 54.8 nm, the PDP increases from 4.3 to 10.4 μJ/cm2. Moreover, the lower the barrier height, the more dominant the temperature-dependent current. For example, vFETs with graphene–WS2 heterostructure exhibited temperature-dependent performances: the ION increased by around 1 order, and the ION/IOFF decreased by approximately 2 orders19. The dependence originates from the transport mechanism of the vFET: the thermionic emission. Therefore, when optimizing the barrier height of the semiconductor-less transistor, the upper limit is determined by the device performances—ION, τ, and fT—and the lower limit is by PDP and the thermionic emission current.Lastly, the other performances such as hBN aggregated in its defect-rich domain44. The analysis is described in Supplementary Note Notably, temperature independence of the performances is the unique property of the semiconductor-less vertical transistor with field-emission current, as shown in Figs. CGate–CTC ratio. (3) The barrier height of graphene–hBN junction decreases with the tTC. (4) The thicker the tTC, the better is the performance of ION, τ, and fT. At the same time, PDP is degraded and temperature-dependent portion of the current increases to induce the temperature dependence of the FEB. Notably, all the characteristics of the semiconductor-less devices with optimized barrier height are temperature independent, unless the defect-rich domain of hBN was used44. Therefore, an optimized device geometry  is indeed a key to realize the temperature-independent transistors with industry-applicable performances.Consequently, the result indicates that the device performances of FEB can be engineered in different ways as follows: (1) the switching of FEB is governed by the capacitive coupling. (2) The intrinsic gain is proportional to the ION/IOFF of 106 in which a ballistic current can be effectively modulated by electric gating; thus the device exhibits not only adjustable gain but also unprecedented temperature-independent performances, such as ION, τ, fT, and PDP. Moreover, we clarified the role of capacitive coupling among the CGate, CTC, and CQ for the modulation of the graphene work function in the vertical device geometry. In our modeling, the CTC is as essential as the CGate. The capacitive coupling is universal for all vertically stacked devices based on van der Waals heterostructures, which exploit the work function modulation of the graphene as their main switching mechanisms. Our FEB achieves industry-applicable device operations with current stability over a wide range of the temperature, which resolves the long-standing issue in conventional semiconductor-based transistors and extends the potential of 2D van der Waals devices to applications in extreme environments.We report the semiconductor-less solid-state switching device with an hBN were prepared by mechanical exfoliation method. It was verified that the graphene is monolayer by using Raman spectroscopy, and the thickness of the hBN was measured by atomic force microscope. To make metal/hBN/graphene/hBN/metal vertical structure, the conventional wet transfer method and dry transfer method, which is called polydimethylsiloxane (PDMS) stamping, were conducted46. First, the hBN flakes were exfoliated onto PDMS surface to find several samples of few layer hBN. After finding two samples of few layer hBN on each PDMS surface using optical microscope, one was transferred onto exfoliated monolayer graphene on SiO2 substrate by using the PDMS stamping method, and the other one was transferred onto Au/Cr gate electrode, which was deposited on 300 nm SiO2 substrate. Second, the sample of hBN/graphene was coated with 950 K PMMA C4 at 4500 rpm by using spin coater. After that, the PMMA-coated hBN/graphene was transferred onto the hBN/metal structure by using the conventional wet transfer method. Third, in case that total thickness of the heterostructure was thicker than 80 nm, the metal/hBN/graphene/hBN junction was coated with the PMMA to make a PMMA bridge. The PMMA was cross-linked by exposure to an electron beam with a very high dose , and the top electrodes were deposited along the cross-linked PMMA by using electron beam lithography and electron beam evaporator.Monolayer graphene and two samples of Field-emission current of the device was measured in vacuum probe station and physical property measurement system at various temperatures with Keithley 4200.Supplementary InformationPeer Review File


Long interspersed nuclear element-1 (LINE-1 or L1) is the only autonomously active retrotransposon in humans. While L1 has been implicated in several pathologies and the aging process, I present a model which challenges an understanding of L1 as predominantly antagonistic to human health. I hypothesize that L1 serves as a reporter in an early cancer alert system: a tripwire strung throughout the genome poised to trigger p53 and a type I interferon (IFN-1) response when the epigenetic landscape portends cancer. Cell proliferation and a shift to aerobic glycolysis cause dramatic changes in the epigenome which are permissive to L1’s escape from suppression. L1 has several properties which make it particularly apt to fulfill this hypothesized sentinel function. Being present in many copies spread throughout the genome allows it to monitor many regions for epigenetic instability and renders it robust to deactivation by mutation. This proposed cancer alert system would alter the cancer cell fitness landscape discouraging the use of growth-favoring aerobic glycolysis by threatening the activation of tumor-suppressive mechanisms. It also imposes costs on a strategy of non-specific global transcriptional derepression aimed at activating oncogenes. Erroneous activations of this system are predicted to increase the rate of aging, suggesting this represents a case of antagonistic pleiotropy trading prolonged youth for cancer prevention. More research is needed to assess this model.Lay summary: During carcinogenesis the epigenome is remodeled by the Warburg effect and cellular proliferation. These processes globally relax chromatin. This epigenetic environment is permissive to the retrotransposon long interspersed nuclear element-1’s (LINE-1 or L1) escape from suppression. I hypothesize and present evidence for the notion that L1 has been co-opted to serve as a reporter in an early cancer alert system, poised to trigger tumor suppressive mechanisms when the epigenetic landscape portends cancer. This hypothesis describes a potentially major means by which transformation is thwarted early on. The transposable elements (TEs) found in eukaryotic genomes have an evolutionary history dating back hundreds of millions of years . They arI suggest that the current understanding of L1’s relationship to cancer may in some ways be backwards. I hypothesize that L1 identifies and reports on signatures of cancerous epigenetic states to activate tumor suppression pathways.A dysregulated epigenome is a hallmark of cancer and is thought to occur in the earliest stages of tumorigenesis . A globaGlobal hypomethylation of the genome is associated with cell proliferation and cancer . During Another important driver of the shifting epigenetic landscape in cancer is the metabolic reprogramming induced by the Warburg effect . This moIt stands to reason that the dysregulated epigenetic environment observed during carcinogenesis is permissive to L1’s escape from suppression: tightly repressed by heterochromatin in healthy cells, L1 awakens to report on the oncogenic epigenetic reprogramming associated with cell proliferation and aerobic glycolysis . PerhapsP53, a canonical tumor suppressor, is activated by L1 insertional DNA damage , 41. It But why should L1, quite the labile genetic element, be retained to serve this function as opposed to a potentially less dangerous gene? Two of L1’s structural features make it particularly apt for this role. That L1 elements are spread throughout the genome makes it well suited to act as an epigenetic sentinel: many different regions can be monitored for instability. That L1 is present in many copies renders it particularly robust against simple deactivation by loss-of-function mutation. Furthermore, an evolutionary point of view reveals reasons why co-opting L1 for such a capacity may have been readily feasible. Having taken part in an arms race with the rest of the genome, the machinery to detect and suppress L1 would have already been present—L1 had merely to be tamed and the machinery repurposed. There is evidence that p53 has had such a relationship with L1: not only is it activated by L1, it also seems to act as an L1 transcriptional repressor . AnotherA signal detection framework applies to determine the optimal tuning of this reporter system: too hair-trigger a system will mark benign cells for clearance and needlessly inflame tissues. Too high an action threshold and some incipient cancers will fail to be detected. An obvious and crude potential tuning mechanism is modulation of active L1 copy number. The greater the number of activatable elements, the easier it will be to marshal a signaling equivalent of L1; in other words, the greater the sensitivity and the lower the specificity. There is evidence supporting the notion that selection has tuned L1 copy number in humans. Our genome contains more than 500 000 L1 sequences, but almost all of these have been inactivated by mutation . Only arAs depicted, this system comes at a cost. In helping protect from cancer, the inevitable erroneous activations of the system will cause benign tissue to be damaged by sterile inflammation and inappropriate p53 activation will result in a loss of cellularity and a faster depletion of stem cell replicative potential. Both of these effects have been implicated in the aging process . L1 funcWhile this accumulating body of evidence is suggestive, it by no means establishes this model as correct. This model is readily testable as it makes many falsifiable predictions. The most fundamental predictions are that if you supernormally repress or delete L1 you should get earlier cancer occurrence and a slower rate of aging. Conversely, were you to have abnormally low L1 repression, later cancer occurrence and more rapid aging are predicted. Another prediction, described in a previous section but restated here, is that L1 elements whose promoter regions show the most sensitive and specific derepression in response to cancer’s permissive effects on chromatin should be those which are retained in active form.According to this model, the roughly 50% of cancers we observe clinically which are L1 positive must be those that have managed to disarm key elements in this suppression strategy. This is supported by the finding that nearly all L1 positive cancers have mutated p53 . Note thOther clinical observations lend support to this model. Many cancers have been found to overexpress factors which condense chromatin—this would constitute a logical means stifling L1 expression. For instance, Li and Seto report that many cancers overexpress HDACs . FurtherAssessing the overall impact this system has on cancer suppression is difficult from clinical data, which tends to capture disease that has progressed well beyond early transformation. It would be informative to know the fraction of L1 positive, transformed cells which self-abort early in cancer progression. Live imaging of cells containing both an oncogene and a fluorescent reporter of active L1 could go some way toward answering this important question.This hypothesis describes a potentially major means by which transformation is thwarted early on. If accurate, it has significant implications in oncology and gerontology. L1 negative cancers could possibly be responsive to treatments activating L1 using epigenetic modulators, such as DNA demethylases or histone acetyltransferases. While the cancer/aging tradeoff highlighted in this model casts doubts on the suppression of L1 as a viable longevity enhancing strategy for a general population, such an approach may hold promise toward ameliorating particular pathologies associated with L1. Taken together, the data reported on in this article are consistent with the model presented but more research is needed to better assess its veracity. To this end, several model predictions have been outlined.Conflict of interest: None declared.


Graphene is an ideal ultrathin material for various optoelectronic devices, but poor light–graphene interaction limits its further applications particularly in the visible (Vis) to near-infrared (NIR) region. Despite tremendous efforts to improve light absorption in graphene, achieving highly efficient light absorption of monolayer graphene within a comparatively simple architecture is still urgently needed. Here, we demonstrate the interesting attribute of bound state in the continuum (BIC) for highly efficient light absorption of graphene by using a simple Si-based photonic crystal slab (PCS) with a slit. Near-perfect absorption of monolayer graphene can be realized due to high confinement of light and near-field enhancement in the Si-based PCS, where BIC turns into quasi-BIC due to the symmetry-breaking of the structure. Theoretical analysis based on the coupled mode theory (CMT) is proposed to evaluate the absorption performances of monolayer graphene integrated with the symmetry-broken PCS, which indicates that high absorption of graphene is feasible at critical coupling based on the destructive interference of transmission light. Moreover, the absorption spectra of the monolayer graphene are stable to the variations of the structural parameters, and the angular tolerances of classical incidence can be effectively improved via full conical incidence. By using the full conical incidence, the angular bandwidths for the peak absorptivity and for the central wavelength of graphene absorption can be enhanced more than five times and 2.92 times, respectively. When the Si-based PCS with graphene is used in refractive index sensors, excellent sensing performances with sensitivity of 604 nm/RIU and figure of merit (FoM) of 151 can be achieved. Graphene has attracted a high level of research interest due to its exceptional optical, electronical, chemical, and mechanical properties, combined with its unique electronic band structure ,2. For eTo enhance the light absorption of graphene in Vis–NIR region, several mechanisms such as guided-mode resonance ,8,9, cohIn recent years, bound states in the continuum (BIC) have been demonstrated as an effective approach to enhance the interaction between light and matter, examples of present-day uses include directional lasing , magnetoIn this work, near-perfect absorption of the monolayer graphene is realized in the communication band by using the BIC based on the photonic crystal slab (PCS) of Si. The high confinement of light and near-field enhancement in the Si-based PCS with a slit contributes to the unexpected improvement of graphene absorption, where BIC turns into quasi-BIC due to the symmetry-breaking of the structure. Theoretical formulas based on the coupled mode theory (CMT) are derived that can well evaluate the absorption performances of graphene integrated with the symmetry-broken PCS. The absorption properties of the monolayer graphene are robust to the variation of the structural parameters. By using the full conical incidence, the angular bandwidths for peak absorptivity and the central wavelength of graphene absorption can be effectively improved. In addition, excellent sensing performances can be realized when the Si-based PCS with graphene is used in refractive index sensors.2 substrate. The PCS consists of a grating layer and a sublayer, and the structural symmetry of the PCS is broken due to the narrow slit in the sublayer. The refractive index of Si is 3.48, the refractive index of SiO2 is 1.47, and the background is air. In practice, the Si-based PCS with monolayer graphene can be fabricated by combing the chemical vapor deposition (CVD) with nanolithography processes. Firstly, the monolayer graphene is directly deposited on the bare SiO2 substrate using the copper-vapor-assisted CVD technique [3 + SF6 gas mixture, and O2ashing for residual photoresist mask removal [The schematic image of the Si-based PCS with monolayer graphene is shown in echnique . Next, technique . Finally removal .gt = 0.34 nm, and its relative permittivity can be written as gε = 1 + gjσ/0tgωε, where gσ represents the graphene surface conductivity, ω indicates the angular frequency, and ε0 is the vacuum permittivity. According to the Kubo formula, the graphene surface conductivity gσ can be written as the sum of the intraband intraσ and interband conductivity interσ [ħ and e are reduced Planck’s constant and the elementary charge, respectively. cμ is the chemical potential, Bk is the Boltzmann constant, τ is the momentum relaxation time, and Γ = 1/2τ is the phenomenological scattering rate. The physical parameters of the graphene are set as cμ = 0.15 eV, T = 300 K, and τ= 0.5 ps.In the Vis–NIR region, graphene can be modeled as an ultrathin dielectric film with thickness of y σinter :(1)σintry-axis) at normal incidence (θ = 0°). Rigorous coupled-wave analysis (RCWA) [s = 10 nm will significantly alter the spectral responses due to the symmetry-breaking of the structure. In particular, the reflection spectrum is varied abruptly—with the occurrence of two resonant reflection dips, two narrow absorption peaks of graphene are formed at the locations of the two resonances as well. Obviously, the narrow slit in the sublayer is crucial for the selective absorption enhancement of the monolayer graphene.s (RCWA)  is used s (RCWA) . In addis = 0, while it varies abruptly and two Fano resonances are appeared as s is slightly altered (s = 10 nm). In both cases, the reflection responses are similar as in s = 0; the LMRs arise from the coupling between the diffracted orders and the waveguide modes, and the overlapping of the two LMRs will result in broadband reflection with high reflectivity [s = 10 nm, where BIC turns into quasi-BIC due to the symmetry-breaking of the structure [To corroborate the correlation of the location between the resonant reflection dips and the absorption peaks of the monolayer graphene, spectral responses of the Si-based PCS without graphene and with graphene are investigated. As can be seen in ectivity . Howevertructure ,47. At ntructure ,49. As cyH and xE) of electromagnetic fields associated with the LMRs and quasi-BICs of the Si-based PCS without graphene are shown in yz plane. The magnetic field of the LMR#1 is mainly confined in the grating layer and the sublayer, and the moderate enhancement of the magnetic field with the maximum amplitude of 6.17 is responsible for large rejection bandwidth and low Q resonance of the Si-based PCS. In yz plane, and the field distributions show the typical radiation patterns of electric dipole aligned with the x-axis. Leakage radiation to the surface normal direction is permitted due to the symmetry-breaking of the structure, which permits the overlap between the incident plane wave and the supported mode and consequently allows coupling between the fields [To gain further insight into the physical basis for the absorption enhancement of the monolayer graphene, distributions of the tangential components  can be effectively tuned by the slit width because its nearfields are mainly localized in the sublayer. By properly selecting the slit width as s = 74 nm with other structural parameters kept the same, near-perfect absorption of the monolayer graphene (97.8%) can be obtained at the wavelength of rλ = 1.55 μm with the full width at half maximum (FWHM) of Δλ = 4.0 nm, as indicated by the theoretical RCWA result in phene 97.% can be ρ) and transmission (ξ) coefficients of the grating-based 1D PCS can be written as [ω0 is the resonant frequency; r and t are the Fresnel reflection and transmission coefficients of off-resonance, as no resonance is taking place in the structure. γ is the external leakage rate of the Si-based PCS, and δ is intrinsic loss rate due to the embedded monolayer graphene. The corresponding intensity of reflection (R) and transmission (T) can be expressed as:To further the quantitative understanding of highly efficient light absorption of the monolayer graphene in the Si-based PCS, theoretical formulas based the CMT are derived here. According to the CMT, the amplitude reflection ρ=δ=0 and r2 + t2 = 1 due to the subwavelength periodicity. In this case, R + T = 1 according to Equations (5) and (6). For the Si-based PCS with graphene, the absorption A = 1–R−T can be written as:Note for the Si-based PCS without graphene, the intrinsic loss rate t2 = 0). In addition, the absorption responses are in the form of the Lorentzian lineshape as ω = ω0). In particular, perfect absorption with A = 100% is realizable at critical coupling with γ = δ if t2 = 0, thus it is feasible to achieve highly efficient light absorption of graphene at critical coupling based on the destructive interference of transmission light within a comparatively simple structure composed of graphene. The absorption responses of the Si-based PCS with graphene are dependent on the off-resonance reflection (r) and transmission (t) coefficients, the external leakage rate (γ), and the loss rate (δ). Therefore, it is possible to achieve high absorption of graphene in the Si-based PCS by tuning the structural parameters.It can be inferred from Equation (7) that the absorption can be simplified as tot of the Si-based PCS with graphene as Qtot = ω0/Δω = ω0/2(γ + δ), where Δω is the FWHM at the resonant frequency ω0, thus we got γ + δ =1.57 × 1012 Hz as Qtot = 387.5. The external leakage rate γ associated with the quasi-BIC mode can be obtained by using the Fano lineshape equation [a1, a2, and b are real number. The external leakage rate can be fitted as γ = 8.07×1011 Hz, and thus δ = 7.63 × 1011 Hz. As shown in To verify the validation of the theoretical model based on the CMT, the absorption response using the CMT is also shown in equation :(8)TFanos, p, d1, d2) on the absorption performances of the Si-based PCS with graphene. As can be seen in s = 0) to the center of the unit cell with s fixed as 74 nm, the location of the absorption peak is blue-shifted, and the peak absorptivity is reduced as well due to the reduced symmetry of the structure. In particular, as the slit approaches the center of the unit cell with Δs = (p − s)/2 = 308 nm, the Si-based PCS becomes the symmetrical structure, and the absorption peak of graphene is vanished due to the symmetry incompatibility between the BIC mode and the external radiation. In d1 mainly changes the absorption bandwidth of the graphene. However, the variation of d2 mainly results in the shift of absorption peak of graphene because the mode profiles of the quasi-BIC#1 are mainly confined in the sublayer. Key parameters of the absorption spectra of the Si-based PCS with graphene are listed in rλ, Apeak, and FWHM denote the absorption wavelength, the peak absorptivity, and the absorption bandwidth, respectively. Note the graphene absorption associated with the quasi-BIC mode is relatively stable to the variations of the structural parameters of Δs, p, d1, and d2, which facilitates the robust control of absorption enhancement of graphene integrated with the Si-based PCS.To evaluate the robustness of graphene absorption associated with the quasi-BIC, we firstly investigate the structural parameters (Δxzθ) is varied in the xz plane. As can be seen in xzθ = ±4°. Note because the Si-based PCS with a slit is anti-symmetric with respect to its mirror-symmetry plane (yz plane), the absorption spectra of graphene for the ±xzθ are slightly different. yzθ) is varied in the yz plane. It can be seen that the angular tolerance of graphene absorption can be effectively improved compared with that of the classical incidence, and the peak absorptivity of 47.0% can be achieved even at yzθ = ±20°. In this case, the absorption spectra for the ±yzθ are exactly the same because the incident angle is varied within the mirror-symmetry plane of the structure. Therefore, the angular tolerance for peak absorptivity of graphene at classical incidence can be enhanced more than five times by using the fully conical incidence. In general, the leaky modes of the grating-based metasurface are essentially related to the diffraction orders, and the angular variations of the mth-order diffracted wave vector for classic (|Δkdiff|classic) and full conic (|Δkdiff|fully conic) incidences can be written as [k0 is the wave vector of the incident light, θ is the incident angle. In the subwavelength regime, (p < λ0), and kdiff|classic via Taylor series expansion as:We further characterized the incident angle and polarization angle dependence of the Si-based PCS with graphene. itten as :(9)|Δkdikdiff|fully conic is always smaller than |Δkdiff|classic, thus the absorption spectra at fully conical incidence is more robust than that at classical incidence as the incident angle is varied.According to Equation (11), |Δxzθ) and fully conical (yzθ) incidences, and the structural parameters are the same in both two cases. As shown in xzθ is slightly deviated from normal incidence due to the decreased symmetry of the structure. Compared with the previous Si-based graphene absorbers that can achieve high absorption at 1.55 μm only at oblique incidence within a small angle range of ±1.5° [ϕ = 0° and ϕ = 90° correspond to the TM and TE polarizations , respectively. As can be seen in of ±1.5° ,55, the λpeak/Δcn and figure of merit (FoM) = S/Δλ, where Δλpeak is the peak wavelength change with the refractive index change Δcn. and Δλ is the half-width of the absorption band. As can be seen in cn. The reflection dip of Si-based PCS with graphene is red-shifted with the increase in cn, but the reflectivity of the reflection dip is slightly increased due to deviation from the critical coupling for perfect light absorption of graphene. In Finally, we showed that the Si-based PCS can function as a high sensitivity refractive index sensor due to the robust absorption of the monolayer graphene. Here, we evaluate the refractive sensing capabilities of the Si-based PCS with sensitivity S = ΔWe provide a novel approach to achieve highly efficient light absorption of monolayer graphene via quasi-BIC by employing a compact Si-based PCS with a slit. Near-perfect absorption of the monolayer graphene can be realized due to the high confinement of light and near-field enhancement in the Si-based PCS, where BIC turns into quasi-BIC due to the symmetry-breaking of the structure. The derived formulas based on the CMT can well evaluate the absorption performances of graphene integrated with the symmetry-broken PCS, indicating that high absorption efficiency of graphene is feasible at critical coupling based on the destructive interference of transmission light within a comparatively simple two-port system. The excitation of the quasi-BIC of the Si-based PCS is robust to the variation of the structural parameters such as the lateral shift of the slit, the period, the thickness of the grating layer and the sublayer, and high absorption of graphene can be maintained even the structural parameters are significantly altered. Moreover, the angular tolerance of graphene absorption for the classical incidence can be effectively enhanced by using the full conical incidence, the angular bandwidths for the peak absorptivity and for the central wavelength of 1.55 μm can be enhanced more than five times and 2.92 times, respectively. When the Si-based PCS with graphene is used in refractive index sensors, excellent sensing performances with sensitivity of 604 nm/RIU and FoM of 151 can be realized. The proposed architecture together with its design principle reveals the potential implementation of BIC for extraordinary absorption enhancement of monolayer graphene, which may provide a guide to design graphene and other 2D material-based optoelectronics devices.