Interlayer coupling in graphene-based van der Waals (vdW) heterostructures plays a key role in determining and modulating their physical properties. Hence, its influence on the optical and electronic properties cannot be overlooked in order to promote various next-generation applications in electronic and opto-electronic devices based on the low-dimensional materials. Herein, the optical and electrical properties of the vertically stacked large area heterostructure of the monolayer graphene transferred onto a monolayer graphene oxide film are investigated. An effective and stable p-doping property of this structure is shown by comparison to that of the graphene device fabricated on a silicon oxide substrate. Through Raman spectroscopy and density functional theory calculations of the charge transport characteristics, it is found that graphene is affected by sustainable p-doping effects induced from underneath graphene oxide even though they have weak interlayer interactions. This finding can facilitate the development of various fascinating graphene-based heterostructures and extend their practical applications in integrated devices with advanced functionalities. Owing to the experimental and theoretical studies on 2D-vdW materials, unprecedented developments in fundamental science as well as the industrial fields have been accomplished. As 2D-vdW material-based components such as transistors, memories, energy harvesters, and sensors have shown immense potential for applications in advanced logic systems, extensive research efforts have been focused on overcoming the performance limits of the single 2D material8. Among the different types of 2D-vdW materials investigated to realize optimal devices, vertically combined structures are promising candidates to achieve high-efficiency logic components and overcome current performance limitations of the individual 2D-vdW materials9.Various two-dimensional (2D) van der Waals (2D-vdW) materials have been investigated for promising applications in futuristic electronic systems10, solar cells11, and light-emitting diodes12 have been introduced to improve and optimize the devices for a wide range of industrial applications. However, in the 2D-vdW heterostructures, interlayer coupling can usually cause unintended phenomena during the operation of the designed device. Therefore, understanding the physical and chemical interactions between the vertically combined vdW heterostructures is key to the design and modulation of device operation based on the requirements. For investigating the interlayer coupling effect in combined structures, graphene and graphene oxide (GO) have an advantage, as the intrinsic properties of both materials can be modulated by an external stimulus and/or chemical adsorption. Therefore, the interlayer interaction between graphene and GO films in a heterostructure can be clearly identified by comparing the experimental results with theoretical expectations.Owing to the atomically flat and well-defined clean interfaces, vertical hetero-structures allow unlimited combinations that can be optimized for various conceptual devices based on the demands. As a result, many devices such as graphene barristors15. Three types of field-effect transistor (FET) devices were fabricated in each area of the graphene, GO and graphene/GO sheets to compare the electrical and optical properties. The experimental strategies employed in this study can be utilized not only to reveal the physical origins of graphene doping effects in vdW hetero structures but also for designing new 2D vdW structures for applications in various conceptual electronic systems as well as their optimization for use in electrical and optical components.In this study, the interlayer coupling effect on the electrical charge transport and Raman spectroscopy measurements is investigated in vertically stacked graphene on GO films. The similarities and differences from the individual materials are carefully identified through experimental and computational studies. Using chemical vapor deposition (CVD) grown monolayer graphene and GO prepared via photochemical treatment, graphene/GO heterostructure was obtained by transferring graphene onto GO2/Si substrate. As shown, GO films are prepared by UV irradiation of the graphene film deposited on the SiO2/Si substrate. Excimer UV irradiation with a wavelength of 172 nm is used for oxidation at room temperature at ambient conditions within 1 min without wet chemical treatment  and Au (90 nm) are sequentially deposited to provide an electrical contact on FET devices. The three types of FET devices with transport channels denoted as graphene, GO, and graphene/GO are prepared as shown in Fig. Figure ent Fig. . Thereafate Fig. . The thiate Fig. . Three t17, the most conventional method does not employ UV-irradiation, but instead involves dispersion using filtered graphite oxide flakes18. In these methods, GO is obtained via several steps of chemical treatment. The process not only requires several hours for completion, but the treated surface is also covered with inhomogeneous functional groups such as hydroxyl (-OH), carboxyl (-COOH), and epoxide (-O-) groups. Because the electrical properties of CVD graphene can be easily modified by charged impurities or chemical components dispersed on the GO surface as well as the substrate, UV-irradiation technique is employed in this study to obtain a clean GO surface , broad G peak (~1595 cm−1), and discernible D + G peak (~2944 cm−1) are observed21. As shown in Fig. −1) of the GO sample is observed in comparison to that (1595.5 cm−1) of the graphene sample. Despite the changes in the Raman spectrum of graphene due to UV irradiation, the optical contrast of the graphene layer on SiO2 substrate did not change significantly, and the graphene was indistinguishable from GO under optical microscopy . The calculated peak positions of G, D′, and D″ peaks obtained by fitting are 1597.1, 1623.3, and 1513.5 cm−1, respectively. These results are intriguing, and several possible explanations have been suggested for the blue shift of G peak in GO. One explanation is based on the double bonds and the other on the D′ band. In theoretical calculations, the alternating pattern of the single-double carbon bonds within the sp2 carbon ribbons yields blue-shifted high-intensity Raman bands24. Other studies have suggested that the merging of D′ band (~1620 cm−1) can also be partially responsible for this blue shift. The presence of D′ band can be explained by the disorder-induced phonon mode above the G band due to crystal defects26.For a detailed analysis of this behavior, the Raman spectrum of GO was fitted with multiple peak functions in the 1500–1700 cm27. However, the typical Raman spectrum for the twisted bilayer graphene is not observed in the graphene/GO structure in the present study31. Thus, it is concluded that the observation of the summation of individual Raman spectra of the two stacked layers is a unique property of the vdW heterostructures of G and GO, without any interlayer interactions32.Next, the Raman spectroscopy results for the graphene/GO region were examined. Interestingly, for graphene/GO, the Raman spectrum appears to be a simple mathematical summation of those for graphene and GO. To confirm this observation, the Raman spectrum of the graphene/GO region was analyzed by comparing it to the mathematical summation of the spectra obtained from graphene and GO regions. As shown in Fig. VDirac), carrier density (n), mobility (µ), and resistance in CNP (RCNP) for each device are listed in Table VDirac, but the current level is significantly different by an order of magnitude. Both graphene and graphene/GO exhibit similar current levels, but wider transfer curve characteristics and higher Dirac point are observed for the graphene/GO device. To confirm the repeatability and reliability of these trends, additional FET devices were fabricated and characterized by back-gate-induced measurements. All devices showed the same tendencies with respect to variations in VDirac, current level, and I–V curve slope . VDirac is the Dirac point estimated at the conductance minimum of the graphene channel during the gate voltage (VG) sweep, n is the carrier density, and μ represents the mobility of graphene FET. A higher carrier density of GO in comparison to that of graphene is due to the functionalities on the surface of GO. Carrier density in graphene/GO is almost equal to the summation of the carrier densities in graphene and GO regions.The resistance of the transport channel is defined as Eq. 331\documRCNP as a function of VDirac distributions for each channel. Although the CNP position increases more than three times for graphene/GO in comparison to that for graphene and the resistance of GO is higher than that of graphene, no significant change is observed in the resistance of graphene/GO compared to graphene. Furthermore, the electrical properties of GO and graphene/GO exhibit excellent stabilities without any noticeable changes in the mobility and resistance for a year even when these are kept at ambient conditions.Figure 34 implemented in the Vienna Ab-initio Simulation Package (VASP) with a projector augmented wave (PAW)35 method, within the generalized gradient approximation (GGA) by Perdew, Burke, and Ernzerhof (PBE)36 theoretical calculations. Geometry optimization of the structures is carried out until the Hellmann–Feynman force acting on each atom is less than 0.01 eV/Å. We use 5 × 5 graphene and 5 × 5 graphene with 2 oxygens in the unit cell. The first Brillouin zone integration is performed using the Monkhorst–Pack scheme, and 5 × 5 × 1 k-point sampling for graphene on graphene oxide is used. Figure 38. Additionally, a Dirac cone-like feature is observed at the K-point with a very small gap (~0.05 eV) as shown in Fig. To explain the high doping effect of G/GO, first-principles calculations were performed for the structure of graphene/GO using density functional theory (DFT)In conclusion, the graphene/GO structure is the thinnest vdW heterostructure known, which enables effective p-doping without chemical bonding. Raman spectroscopy measurements and electrical transport analysis, together with the corresponding simulations of the graphene/GO structure, confirm that there is no chemical bonding between graphene and GO layers. However, the electrons can flow from the graphene sheet owing to the difference in charge density, which is due to the presence of oxygen groups in GO, exhibiting a p-doping effect in the graphene layer. Additionally, these effects are observed for a long time under ambient conditions, affording almost perpetual p-doping effect on the surface of graphene deposited on GO. We suggest that the monolayer GO can be used as the thinnest hole-dopant supplier sheet for graphene without affecting its resistance value. Furthermore, by substituting the oxygen groups of GO by n-type-inducing functionalities, a graphene p-n junction can be obtained in a facile manner. We believe that our work could be stepping-stone for realizing various conceptual devices based on partial doping distributions using the 2D heterostructures and further could be contribute to engineering and modulating the electronic and optoelectronic applications.4 and H2 (1:2) gas mixture for 20 min. The graphene on the Cu film was spin-coated with poly methyl methacrylate . Cu foil was etched by floating on 0.1 M ammonium persulfate ((NH4)2S2O8) aqueous solution. After rinsing several times with deionized water, the graphene film was transferred onto the SiO2/Si substrate. Then, the PMMA layer was removed using acetone, followed by rinsing and drying with isopropyl alcohol (IPA) and N2, respectively.Monolayer graphene was grown on a Cu foil  at 1000 °C via tube-type thermal CVD (T-CVD) with a flow of CH2 was used for oxidation at room temperature at ambient conditions without any wet chemical treatment. Optimized UV irradiation time is determined by Raman analysis.  using a diode laser with a wavelength of 532 nm. The laser power was set to 1 mW to prevent any destructive effects on graphene and GO atomic layers. The laser source was vertically exposed onto the device surface through a ×100 objective lens and the position of the sample was controlled within micrometer accuracy by a piezo stage.−6 Torr. Si and SiO2 in the SiO2/Si substrate act as the gate and gate insulator, respectively. The I-V curves were obtained by measuring the current flow in the channels of the FET devices while controlling the bias voltage and gate voltage sweep.The I-V characteristics of the devices were investigated by electrical transport measurement using a vacuum probe station connected to Keithley 4200-SCS parameter analyzer. All electrical measurements were performed under a high vacuum of below 10Supplementary information.


We consider the effect of atomic impurities on the energy spectrum and electrical conductance of graphene. As is known, the ordering of atomic impurities at the nodes of a crystal lattice modifies the graphene spectrum of energy, yielding a gap in it. Assuming a Fermi level within the gap domain, the electrical conductance diverges at the ordering of graphene. Hence, we can conclude about the presence of a metal–dielectric transition. On the other hand, for a Fermi level occurring outside of the gap, we see an increase in the electrical conductance as a function of the order parameter. The analytic formulas obtained in the Lifshitz one-electron strong-coupling model, describing the one-electron states of graphene doped with substitutional impurity atoms in the limiting case of weak scattering, are compared to the results of numerical calculations. To determine the dependence of the energy spectrum and electrical conductance on the order parameter, we consider both the limiting case of weak scattering and the case of finite scattering potential. The contributions of the scattering of electrons on a vapor of atoms to the density of states and the electrical conductance of graphene with an admixture of interstitial atoms are studied within numerical methods. It is shown that an increase in the electrical conductance with the order parameter is a result of both the growth of the density of states at the Fermi level and the time of relaxation of electron states. We have demonstrated the presence of a domain of localized extrinsic states on the edges of the energy gap arising at the ordering of atoms of the admixture. If the Fermi level falls in the indicated spectral regions, the electrical conductance of graphene is significantly affected by the scattering of electrons on clusters of two or more atoms, and the approximation of coherent potential fails in this case. Modifications of graphene with impurities, defects, and chemical functional groups are of increasing interest, as they change the physical properties of graphene and make it a basic system, generating a new class of functional materials. Such materials can be supposedly used in nanoelectromechanical systems, systems of accumulation of hydrogen, etc. as competitors of silicon in electronic devices, though the quasirelativistic spectrum of charge carriers in graphene hampers its application, for example, in field transistors due to the absence of a gap in its spectrum. However, it is worth noting that the impurities can induce the appearance of such a gap.Indeed, within the self-consistent meta-gradient approximation and the method of projection of adjoint waves , the numSimilar calculations for graphene with impurities of aluminum, silicon, phosphorus, sulfur, boron, nitrogen, and lithium were executed in works ,4, whereIt is clear that the numerical calculations should be supported by a simple but adequate model presenting the exact analytic solutions. The theory of the modification of the spectrum of graphene caused by an increase in the concentration of point impurities was developed in works ,6,7, wheThe Kubo–Greenwood quantum-mechanical formalism in the Lifshitz one-band model was applied in ,11,12,13We note that, having the Fermi level falling in the gap domain, the velocity of an electron can lower its speed on such a level. This leads to a decrease in the mobility of electrons and in the electrical conductance, which can worsen the functional characteristics of graphene.Introducing the notation  in Ref.  that a gIt is worth indicating the different nature of a gap in the energy spectrum of graphene related to edge effects. Work  presentsIn recent times, several tens of works have been published on the influence of various types of deformations on the electron properties of  graphene . The reThe goal of the present work is to clarify the nature of the influence of the ordering of a substitutional impurity on the appearance of a gap in the energy spectrum and on the electric conductance of graphene.The conclusions in work  were basIn the present work, we will consider the interconnection between a change in the electrical conductance, changes in the energy spectrum, and the decay time for electron states under the ordering of impurity atoms in graphene.The Hamiltonian in the Lifshitz one-electron strong-coupling model describing the one-electron states of graphene doped with substitutional impurity atoms can be presented in the following form :(1)H=∑niLet us add to and subtract the translationally invariant operator The formula for the coherent potential will be given below.z, is defined asThe retarded Green’s function of graphene, which is an analytic function in the upper half-plane of values of the complex energy T-matrix can be presented in the form of an infinite series [I is the identity operator. A Green’s function satisfies the equatione series :(6)T=∑n1The terms of Equation (6) describe the processes of multiple scattering of electrons on clusters comprising one, two, three, etc. scattering centers. In work , it was γiε , as the Neglecting the contributions of the processes of scattering on clusters of three or more atoms, which are small due to the parameter ing form :(9)gε=1T = 0) as [Using the Kubo–Greenwood formula  and negl = 0) as (10)σαβ=The operator of the electron velocity projection integral  and rnj μ is determined from the relationThe Fermi level In Equations (9) and (10), In Equations (9) and (10), The probabilities are determined by the interatomic pair correlations 0iBB via ,28(16)PHere, The coherent potential can be determined from the condition equation (18)σi=〈Setting Solving the system of Equations (11) and (18), we find the values of the coherent potentialIn the limiting case of weak scattering olutions . It was Equation (15) implies that the maximum order parameter At the electron concentration n occurs .At the electron concentration ameter η . As the We recall that the contributions of the processes of the scattering of electrons on clusters to the density of states and to the electrical conductance decrease and are guided by some small parameter γiε , as the The parameter the form (22)γiε=Using formula ained in  in the lThe parameter 0iε/dε→∞ , whereasxxσ·d enters the formula for the electrical resistance of a graphene layerl is the length of a graphene layer along the axis x, and L is the layer width. Here, x is directed from a carbon atom to its nearest neighbor. The values of xxσ·d are given in units of Thus, the processes of scattering on clusters give a significant contribution to the density of states at the energies of electrons lying in interval (Equation (23)). The product η, we consider both the limiting case of weak scattering, To establish the nature of the dependence of the electrical conductivity η tends to its maximum value, If the order parameter For the three-dimensional crystals with a simple lattice in the approximation of effective mass, Equation (25) with the corresponding g(ε) by Equation (9) at the substitutional impurity concentration In It is seen from g(ε) of graphene, which is calculated in the approximation of coherent potential according to the first term in Equation (9). The dotted curve gives the density of states g(ε) calculated with regard to the processes of scattering on the pairs of atoms located in the limits of the first coordinate sphere in the case of the completely disordered arrangement of impurity atoms, g(ε), calculated with regard to the processes of scattering on the pairs of atoms in the limits of three coordinate spheres and in the limits of ten coordinate spheres, practically coincide with the results of calculations that consider the scattering on the pairs in the limits of the first coordinate sphere. Thus, we may conclude that the domain of electron states of an impurity in graphene in the model under study is spatially bounded by the first coordinate sphere. In g(ε) and the electrical conductance xxσ(μ) as functions of the energy ε and the Fermi level μ, respectively; d means the thickness of a graphene layer. The calculations of g(ε) and xxσ(μ) are carried out by Equations (9) and (10). The values of the energy ε and the Fermi level μ are given in units of the energy zone half-width In δ/w=−0.2 , and δ/wδ/w=−0.6 . g(ε) = 0 (xxσ(μ) for the Fermi level located in the gap is equal to zero. For the Fermi level outside the gap, the electrical conductance of graphene is nonzero and increases with the density of states on the Fermi level.g(ε) = 0 a. The elAs distinct from the above-described limiting case of weak scattering ng δ/w≪1 .xxσ on the scattering potential η, we present the dependence of the electrical conductance of graphene xxσ on the order parameter of impurity atoms η for different values of the scattering potential μ(η) calculated by Equation (14) lies to the right of the energy gap. In μ(η) as a function of the order parameter of an impurity η. In ig(μ) at the Fermi level on the order parameter of an impurity η; i = 1, 2 is the number of a sublattice. η. With the purpose to clarify the character of the dependence of the electrical conductance η. It is seen from xxσ agree qualitatively with the formula obtained in the limiting case of weak scattering xxσ on the ordering parameter η. We have considered such values of concentrations and scattering potentials, at which the Fermi level lies in the vicinity of the Dirac point, as well as outside it. The numerical results presented in ng δ/w≪1  and withng δ/w≪1 , on the η tends to the maximum value, As the order parameter g(ε) calculated with regard to the processes of scattering on the pairs of atoms located in the limits of three coordinate spheres and in the limits of ten coordinate spheres practically coincide with the results of calculations involving the scattering on the pairs located in the limits of the first coordinate sphere. Thus, we may conclude that the domain of electron states of the impurity in graphene in the model under consideration is spatially bounded by the first coordinate sphere. We showed the existence of domains with localized extrinsic states on the edges of the energy gap arising at the ordering of atoms of the admixture. If the Fermi level falls in the indicated domains, the processes of the scattering of electrons on clusters consisting of at least two atoms contribute essentially to the electrical conductance of graphene, and the approximation of coherent potential fails in this case.We note that values of the density of states and the electrical conductance of graphene cannot be used, if the Fermi level falls in the interval (Equation (23)) of energies at the gap edges. The values of the density of states η and the difference in the scattering potentials We have established that, at the ordering of impurity atoms, a gap appears in the energy spectrum of graphene. Its width depends on the order parameter In the limiting case of weak scattering At the electron concentration xxσ increases with the order parameter If the Fermi level lies outside the gap, the electrical conductance xxσ of graphene with the order parameter η of impurity atoms is caused by an increase in the density of states at the Fermi level, An increase in the electrical conductance


Unlike graphene, penta-graphene exhibits a non-zero bandgap, which opens the possibility of its use in optoelectronic applications. However, as the observed bandgap is large, gap tuning strategies such as doping are required. In this work, density functional theory calculations are used to determine the effects of the different number of line defects of substitutional nitrogen or silicon atoms on the penta-graphene electronic behavior. Our results show that this doping can induce semiconductor, semimetallic, or metallic behavior depending on the doping atom and targeted hybridization (sp2 or sp3-like carbons). In particular, we observed that nitrogen doping of sp2-like carbons atoms can produce a bandgap modulation between semimetallic and semiconductor behavior. These results show that engineering line defects can be an effective way to tune penta-graphene electronic behavior.Penta-graphene is a quasi-two-dimensional carbon allotrope consisting of a pentagonal lattice in which both  This carbon allotrope that is composed of a hexagonal lattice was demonstrated to possess several exciting features, such as high electrical and thermal conductivity and large mechanical resistance that are aimed at developing the next generation of organic optoelectronic devices4. However, when it comes to optoelectronic applications, graphene has a zero bandgap, which precludes its use, for instance, as active material in solar cells. To overcome this issue, gap opening strategies have been developed7 including the cutting of graphene sheets into graphene nanoribbons8, the adsorption of H-adatoms9 and the use of dopants12. Recently, the effects of such techniques have also been studied in similar 2D materials such as arsenene14, by means of first principle calculations.Research on 2D materials has gained much attention since the discovery of graphene15. The former makes use of the spin coating of dopant containing solutions so that charge transfer between graphene and dopant may take place. Dry doping strategies, on the other had, include the electrostatic field doping method, which consists on the application of an electric field perpendicular to the graphene sample. This method, however, cannot be applied to single layers of graphene. A more appropriate strategy in the context of this work is the atom substitution method, which can be performed by means of thermal treatment or plasma doping, for instance.When it comes to doping strategies, these are often divided into wet and dry doping methods16, and carbon nanotubes17. Recently, another allotrope was proposed named penta-graphene18  produce significantly different results in terms of electronic behavior. Silicon doping allows us to tune the bandgap when replacing sp3-like carbons and produces metallic behavior when replacing sp2-like ones. Nitrogen doping replacing sp3-like carbons results in a transition from semiconductor to semimetallic to a metallic character. Nitrogen doping replacing sp2-like carbons produces an alternating behavior between semimetallic and semiconductor depending on the number of dopants. These results indicate that engineered line defects can be a very effective way to tune penta-graphene electronic behavior.Herein, we carried out density functional theory (DFT) calculations to address the effects of the systematic substitutional doping of either see Fig. . As to tsp3 or sp2-like carbons forming engineered line defects. The cases of 1 up to 7 line defects were considered. In this sense, Fig. sp3 case, which is similar to the sp2 one. Figure In the present work, we investigated the electronic and structural features of penta-graphene lattices with substitutional doping (N or Si) either at Significant structural differences take place in the morphology of the resulting doped structures. For the nitrogen cases, an overall decrease in bond length values was observed, as presented in Fig. 21. We have obtained a similar value, as shown in Fig. sp3 cases for nitrogen  behavior, as can be seen in Fig. N, semiconducting properties are obtained with almost direct bandgaps that decrease as N grows larger from 2.4 eV for N = 0 to 0.6 eV for N = 6. In contrast, for odd values of N, the valence band maximum (VBM) touches or surpasses the Fermi levels. However, the DOS near the Fermi level is very small, increasing progressively with N. This behavior can be better visualized in the PDOS plots of Fig. N nitrogen-doped penta-graphene lattices display a semimetallic character, with carbon p orbitals being mostly responsible for the DOS in the vicinity of the Fermi level.In terms of electronic structure, nitrogen and silicon doping produce completely different results. Interestingly, for the N values, the structures become fully metallic, as shown in Fig. sp2-like carbons is not as effective as in cases of nitrogen doping regarding decreasing the bandgap value.Silicon doped penta-graphene structures, on the other hand, possess semiconductor properties only for N = 1 or N = 2, with a fast transition to bandgap closing. For larger sp2 doping instead of sp3 one is the effects on the structural stability of the doped structures. In Fig. Ecoh) values for all doping scenarios. The cohesive energy is the difference per atom between the entire system energy and the sum of the individual energies of its constituents. It is, therefore, associated with the stability of the system. Such a quantity is evaluated by the following expression:Etotal is the total energy of the system. ND and NC are the number of dopant and carbon atoms of the system, respectively, and Ntotal = ND + NC. ED and EC are the energies of isolated dopant and and carbon atoms, respectively.An important advantage concerning the sp3 and sp2 results, respectively. It can be seen from this figure that for both sp3 and sp2-like carbon doping, the effects on cohesive energy are similar for N and Si dopants. However, whereas sp3-like carbon doping increases the cohesive energy from −8.0 eV/atom to −6.5 eV/atom, the corresponding increase in the case of sp2-like carbon in less than 1.0 eV/atom.Figure Finally, we present the charge transfer analysis for all the modeled systems studied here. Figure 28 along with the DZP30, basis set. Relativistic pseudopotentials parameterized within the Troullier-Martins formalism were also considered31. These combined approximations can accurately describe the magnetic and electronic properties of materials composed of atoms with many electrons. All the calculations were performed considering spin polarization. For the bands and density of states calculations, Monkhorst pack grid of 21 × 21 × 3 was used32. A mesh cutoff of 200 Ry was chosen as a parameter for our calculations33. The force criteria convergence was 0.001 eV/Å. In order to establish a good compromise between the accuracy of our results and computational costs, the tolerance in the matrix density and total energy was set to 0.0001 and 0.00001 eV, respectively. All calculations were performed with the SIESTA software suite35.DFT calculations were carried out within the Generalized Gradient Approximation (GGA) scheme as proposed for Perdew, Burke, and Ernzerhof (GGA/PBE)sp3 or sp2-like carbons. Regardless of the type doping, for the nitrogen cases, we observed an overall stiffening of the penta-graphene structures. On the other hand, for the silicon doping cases, we observed only the stretching of Si-C bonds and compression of the remaining C–C bonds.In summary, we have carried out DFT calculations to assess the changes in the structural and electronic properties of penta-graphene lattices resulting from selective N and Si doping (engineered line defects) of either sp3-like carbons preserves the penta-graphene semiconductor character. The smallest observed bandgap value was 0.8 eV (2.4 eV for pristine penta-graphene) for the 4 line defect case. For a larger number of line defects, the bandgaps increase again. On the other hand, for Si doping sp2-like carbons, the result is a fast transition to metallic behavior.From an electronic structure perspective, both the doping type and doping atom selection produce significantly different results. Silicon doping of the sp3-like carbons, the doping results in a progressive changes from semiconductor to metallic behavior. For the case of 1 line defects, the doped penta-graphene structure becomes an n-type semiconductor with a 1.5 eV bandgap. For 2 and 3 line defects, the bandgap closes, but the density of states near the Fermi level goes to zero, giving the material a semi-metallic character. From this point on, further doping leads to true metallic behavior.Nitrogen doping produces more interesting results. For the sp2-like carbons, we observed a bandgap modulation behavior . For even numbers of line defects, the bandgap decreases with the number of line defects. In contrast, for odd numbers of line defects, a semi-metallic behavior is observed, combining zero bandgap with near-zero density of states at the vicinity of the Fermi level. Finally, the cohesive energy values indicate that doping the sp2-like carbon affects less the structural stability of the resulting doped structures than sp3-like carbon ones.For the nitrogen doping of 36 have demonstrated the creation of graphene and hexagonal boron nitride (h-BN) in-plane heterostructures with controlled domain sizes by using lithography patterning and sequential CVD growth steps. By employing this approach, the shapes of the graphene and h-BN domains were precisely controlled, and sharp graphene/h-BN interfaces were created. In this way, we believe that such an approach can be employed to yield our proposed model lattices. We hope the present work can stimulate further studies along these lines.These results indicate that selective doping of penta-graphene structures through engineered line defects can be an effective tool to tune their electronic behavior, being possible to create structures that vary from large bandgaps through semiconductors and even metallic or semimetallic ones. Importantly, Liu and coworkersSupplementary information.


Rhus chinensis Mill.) ointment has been shown as an effective treatment for keloids. However, the protective mechanisms of Wubeizi ointment are not fully understood. The mammalian target of rapamycin (mTOR) has been demonstrated to be associated with keloid pathogenesis. In the present study, we investigated if Wubeizi ointment suppressed keloid formation through the modulation of key molecules of the rapamycin (mTOR) pathway including phosphatase and tensin homolog (PTEN), phosphatidylinositol 3-kinase (PI3K), and protein kinase B (Akt).  Wubeizi  followed by pairwise q-tests.  A keloid mouse model and human keloid-derived fibroblasts were developed and treated with Galla chinensis. Immunohistochemistry, western blot, and reverse transcription-PCR were used to detect PI3K, PTEN, Akt, and mTOR in keloid tissues and keloid fibroblasts. The apoptosis and proliferation rate of keloid fibroblasts was, respectively, analyzed by flow cytometry according to the MTT assay. Statistical analysis was done using SPSS version 20.0. For two variable comparisons, a two independent samples  Our in vivo and in vitro studies showed that Wubeizi ointment suppressed keloid formation through inhibition of fibroblast proliferation and promotion of fibroblast apoptosis. The underlying basis involves downregulation of p-Akt and p-mTOR as well as upregulation of PTEN.  These findings may contribute to a better understanding of the mechanisms of Wubeizi ointment for treating keloids. Keloids are formed because of abnormal overgrowth of scar tissue during the healing of skin wounds and are characterized by the proliferation of dermal fibroblast and the aberrant accumulation of extracellular matrix (type I and III) collagens, mucins, and glycosaminoglycans . Wubeiziβ (TGF-β1), PI3K, Akt, and mTOR was significantly increased in pathological scar fibroblasts than in normal skin tissue or fibroblasts [mTOR is a serine/theronine kinase which plays an important role in the regulation of metabolic processes and translation rates. mTOR as a regulator of collagen expression and inhibition of mTOR reduced extracellular matrix deposition. Tissue extracts obtained from keloid scar showed an increase in the expression of mTOR, p70KDa S6 kinase, and their activated forms, suggesting an activation of mTOR in keloid scars . The exproblasts . In addiroblasts . TherefoIn the present study, we investigated the effect of Wubeizi ointment on key molecules of the mTOR pathway including PTEN, PI3K, and Akt. The results may contribute to a better understanding of the protective effect of Wubeizi ointment against keloid pathogenesis.Salvia miltiorrhiza, Clematis, black vinegar, Galla Chinensis, Cortex Lycii, and alum. It was prepared as described previously [The formula of Wubeizi ointment includes Chinese herbs eviously . BrieflyThe keloid scar tissues were obtained from the Department of Dermatology of Xuzhou Hospital affiliated to Nanjing University of Traditional Chinese Medicine . The tissues were taken from the anterior part of chest after surgical resection for treatment, from 18 Chinese patients . The normal skin tissue was resected near the keloid scar tissue.n = 6 for each group). For the Wubeizi ointment-treated group, the corresponding concentration of Wubeizi ointment was applied to the skin . For the control group, only the matrix of Wubeizi ointment was applied to the skin .Eighteen nude mice were purchased from the animal facility of Xuzhou Medical University. They were housed under conditions of constant temperature and humidity and with a 12 h light–12 h dark cycle. Keloid models were generated as described previously . BrieflyAfter 30 days of Wubeizi ointment treatment, mice were anesthetized by intraperitoneal injection of 0.1% pentobarbital sodium at 0.1 ml/10 g of body weight and then killed by cervical dislocation, and the keloid tissues were disassociated. The size of the keloid tissues was measured by a vernier caliper as described previously .3) and placed into a flask. Subsequently, 5 ml of 0.25% trypsin solution  was added into the flask. After 14 hours of digestion at 4°C, protease was removed, and 5 ml of complete media containing 10% fetal bovine serum  was added into the flask. Single cell suspension was prepared. Cells were then subcultured in a 25 ml flask and incubated in an incubator  at 37°C with 5% CO2. The generation was passaged every 2–3 days. The 3rd generation cells at logarithmic growth phase were analyzed.The primary cells of the human keloid-derived fibroblasts were disassociated and cultured according to our published procedure . Brieflyμl DMEM containing 5% FBS was added to the culture medium. For the IGF-1-treated group, 20 μl IGF-1  was added. IGF-1 is an agonist of the mTOR signaling pathway. For the IGF-1+Wubeizi ointment-treated group, 20 μl mixture of IGF-1 and Wubeizi ointment was added. For the Wubeizi ointment-treated group, 20 μl of the Wubeizi ointment solution was added. The Wubeizi ointment solution used for in vitro experiments was prepared by dissolving the extract of Wubeizi ointment in water at a concentration of 0.5 mg/ml.Keloid fibroblasts were divided into four groups; i.e., control group, IGF-1-treated group, IGF-1+Wubeizi ointment-treated group, and Wubeizi ointment-treated group. For the control group, 20 μm thickness by Rotary Paraffin Microtome Slicer paraffin embedding machine , and stained with hematoxylin and eosin for routine examination. Subsequently, the keloid sections were incubated with antibodies against p-PI3K , PTEN  monoclonal antibody, Santa Cruz, CA, USA), p-Akt , or p-mTOR . Bound antibodies were visualized using 3,3′-diaminobenzidine (DAB) as a chromogen , and the slides were counterstained with hematoxylin. The positive expression of p-PI3K, PTEN, p-Akt, and p-mTOR was evaluated in four randomly selected fields under a light microscope . The mean optical densities (MOD) of positive expression were quantified with the Image Pro-Plus image analysis system .Immunocytochemistry was conducted as described previously . BrieflyΔΔCt−. Each RT-qPCR experiment was repeated three times.The mRNA levels of PI3K, PTEN, Akt, and mTOR in the keloid tissues and cultured keloid fibroblasts were analyzed as described previously . Brieflyμg) was separated on 15% SDS-polyacrylamide gel, transferred to nitrocellulose membrane, and blocked with 5% skim milk powder for 2 hours at room temperature. Membranes were incubated with primary antibody against PI3K , p-PI3K , PTEN , Akt , p-Akt , mTOR , p-mTOR , and actin  overnight at 4°C, washed with PBS, and then incubated with secondary antibody  and conjugated to horseradish peroxidase for 1 h at room temperature. The membranes were washed with PBS, and immunoreactivity was visualized on Odyssey infrared fluorescence imager . Images were analyzed by using the Image Pro-Plus image analysis system.Western blot was performed as described previously . Brieflyμl MTT was added to each well. After incubating for 4 h at 37°C, the liquid was removed, and dimethyl sulfoxide (150 μl/well) was added. After dissolution of the blue-purple formazan, optical density (OD) was measured 1 h later in a microplate reader  at a wavelength of 490 nm.The proliferation rate of keloid fibroblasts at specific time points  was measured by the MTT assay. The MTT assay was performed as described previously [μl of Annexin V-FITC was added to 2 × 105 cells for 15 min followed by 5 μl PI and incubated in dark at 4°C for 5 min. The cells were subjected to flow cytometry . Dot intensities in both Q2 and Q3 regions indicated the number of apoptotic cells.The apoptosis of keloid fibroblasts was analyzed by flow cytometry according as described previously . Brieflyt-test was used. For multiple variable comparisons, data were analyzed by the χ2 test or one-way analysis of variance (ANOVA) followed by pairwise q-tests.Statistical analysis was done using SPSS version 20.0 . Data were presented as mean ± S.D. For two variable comparisons, a two independent samples 3 (n = 6), which were significantly smaller than the sizes of keloid tissues disassociated from 3% Wubeizi ointment-treated nude mice  and control nude mice  (P < 0.05).As show in P < 0.05). In contrast, compared to the control group, the expression of PTEN significantly increased in keloid tissues from the 3% and 5% Wubeizi ointment-treated group, and the effect was dose-dependent (P < 0.05). However, there was no significant difference between the Wubeizi ointment-treated and control group in the expression of p-PI3K in keloid tissues (P = 0.735).The results of immunohistochemistry showed that most of the p-PI3K, p-Akt, and p-mTOR were expressed in cytoplasm and a small amount of p-PI3K, p-Akt, and p-mTOR was observed in nucleus . In contP < 0.05). In contrast, compared with the control group, mRNA and protein levels of PTEN were significantly increased in keloid tissues from the Wubeizi ointment-treated group, and the effect is dose-dependent . However, there were no significant differences found between the Wubeizi ointment-treated and control group in the mRNA of PIK3CA and phosphorylated protein levels of PI3K in keloid tissues .The results of qPCR and western blot showed that, compared to the control group, mRNA of Akt1 , and phoThese data suggested that Wubeizi ointment could downregulate the mRNA expression levels of Akt1 and mTOR and upregulate PTEN mRNA expression levels in keloid tissues. It also could reduce phosphorylated protein levels of Akt and mTOR in keloid tissues.P < 0.05). In addition, the inhibitory effect of Wubeizi ointment on fibroblast proliferation could be attenuated by IGF-1  (n = 24) (Results of the MTT assay showed that IGF-1 promoted fibroblast proliferation whilst Wubeizi ointment inhibited fibroblast proliferation (by IGF-1 . Results < 0.05) . The inh(n = 24) .P < 0.05).The results of qPCR showed that, compared to the control group, mRNA levels of PIK3CA, Akt1, and mTOR were significantly increased in keloid fibroblasts from the IGF-1-treated group (P < 0.05). However, there was no significant difference between the Wubeizi ointment-treated and control group in PI3K mRNA levels in keloid fibroblasts (P = 0.418). Compared to the control and IGF-1-treated group, mRNA levels of PTEN were significantly increased in keloid fibroblasts from the IGF-1+Wubeizi ointment-treated group and Wubeizi ointment-treated group (P < 0.01). However, there was no significant difference between the IGF-1-treated and control group in the mRNA levels of PTEN in keloid fibroblasts (P > 0.05). In contrast, compared to the control group, mRNA levels of Akt1 and mTOR were significantly decreased in keloid fibroblasts from the IGF-1+Wubeizi ointment-treated group and Wubeizi ointment-treated group (P < 0.05). The mRNA levels of Akt1 and mTOR in keloid fibroblasts from the IGF-1+Wubeizi ointment-treated group was higher than those in keloid fibroblasts from the Wubeizi ointment-treated group (P < 0.05).Compared to the control and Wubeizi ointment treated-group, mRNA levels of PIK3CA were significantly increased in keloid fibroblasts from the IGF-1+Wubeizi ointment-treated group and IGF-1-treated group (P < 0.05).The results of western blot showed that, compared to the control group, phosphorylated protein levels of p-PI3K, p-Akt, and p-mTOR were significantly increased in keloid fibroblasts from the IGF-1-treated group (P < 0.05). However, no significant difference was found between the control and Wubeizi ointment-treated-treated group in the protein levels of p-PI3K in keloid fibroblasts (P > 0.05). Compared to the control and IGF-1-treated group, protein levels of PTEN were significantly increased in keloid fibroblasts from the IGF-1+Wubeizi ointment-treated group and Wubeizi ointment-treated group (P < 0.05). No significant difference was found between the control and IGF-1 group in the protein levels of PTEN in keloid fibroblasts (P = 0.364). In contrast, compared to the control group, protein levels of p-Akt and p-mTOR were significantly decreased in keloid fibroblasts from the IGF-1 + Wubeizi ointment-treated group and Wubeizi ointment-treated group (P < 0.05). The protein levels of p-Akt and p-mTOR in keloid fibroblasts from the IGF-1+Wubeizi ointment-treated group was higher than those in keloid fibroblasts from the Wubeizi ointment-treated group (P < 0.05).Compared to the control and Wubeizi ointment-treated-treated group, protein levels of p-PI3K were significantly increased in keloid fibroblasts from the IGF-1+Wubeizi ointment-treated group and IGF-1-treated group . Aberrant accumulation of extracellular matrix collagens, mucins, and glycosaminoglycans because of an imbalance between collagen production and degradation of the extracellular matrix along can lead to the elevated production of cytokines and proinflammatory responses. Faulty fibroblast regulation resulting in proliferation of fibroblasts and apoptosis inhibition plays an important role in the keloid development and scar formation .Our previous study demonstrated that Wubeizi ointment increased fibroblasts at the S phase thereby greatly reduced dividing fibroblasts in addition to inhibiting the proliferation of keloid-derived fibroblasts in a time- and dose-dependent manner . Moreoveβ1 [β1 through upregulation of the miR-21 and PTEN/AKT signaling pathway [β. Scarring can be reduced in rodents by inhibition of TGF-β signaling proteins [β1 signal transduction [It has been demonstrated that the proliferation of keloid fibroblasts could be regulated by various cytokines, such as TGF-β1 . Keloid  pathway . Keloid proteins . The mTOsduction –12. The sduction . The mTOsduction –19. Pathsduction . These fIt was found that inhibition of mTOR can reduce extracellular matrix deposition , 21. In In conclusion, the present study investigated if Wubeizi ointment inhibited the keloid formation through modulation of key molecules of the mTOR pathway including PTEN, PI3K, and Akt. The results of the in vivo and in vitro studies suggested that Wubeizi ointment inhibited the proliferation of keloid fibroblasts and promoted the apoptosis of keloid fibroblasts, probably through downregulation of Akt and mTOR and upregulation of PTEN. These findings may contribute to a better understanding of the mechanism of Wubeizi ointment for treating keloid and provide a theoretical basis for its clinical application.


The superlattice potential generates a series of Dirac points (DPs) and van Hove singularities (vHSs) within an experimentally accessible low energy state, providing a platform to study orbital moments with respect to band structure. In this work, theoretical calculations and magnetothermoelectric measurements are combined to reveal the emergence of an orbital magnetic moment at vHSs in graphene/h-BN moiré superlattices. The thermoelectric signal for the vHS at the low energy side of the hole-side secondary DP exhibited significant magnetic field-induced valley splitting with an effective g-factor of approximately 130; splitting for other vHSs was negligible. This was attributed to the emergence of an orbital magnetic moment at the second vHS at the hole-side.Bloch electrons lacking inversion symmetry exhibit orbital magnetic moments owing to the rotation around their center of mass; this moment induces a valley splitting in a magnetic field. For the graphene/ h-BN moiré superlattice. Here, Moriya et al. report thermoelectric evidence of magnetic field induced valley splitting for a van Hove singularity in this superlattice, suggesting the emergence of an orbital magnetic moment.An orbital magnetic moment emerges as a result of inversion symmetry broken at the graphene/ The presence of the Berry curvature induces electrons to have anomalous velocity perpendicular to an applied electric field, thus exhibiting the valley Hall effect. The valley Hall effect has been demonstrated at the gapped Dirac band such as gapped bilayer graphene and monolayer graphene/h-BN moiré superlattice6. In contrast to this, an orbital magnetic moment will induce an energy shift under the application of the perpendicular magnetic field; this is known as valley Zeeman splitting and has been demonstrated in gapped bilayer graphene9 as well as transition metal dichalcogenides10. Both Berry curvature and orbital magnetic moment, in principle, strongly depends on the local structure of the band. Here we choose graphene/hexagonal-boron nitride (h-BN) as a model system to investigate the orbital magnetic moment in relation to the band structure.Berry curvature and orbital magnetic moment are two pseudovectors that are observed in the presence of spatial inversion asymmetry. These enable us to control valley contrasting phenomena in two-dimensional materialsh-BN insulator through van der Waals force, two significant changes occur in the band structure. First, the interaction between graphene and h-BN breaks the spatial inversion symmetry of graphene. Second, the lattice mismatch between two crystals generates a moiré pattern  derived from Fig. 19. These result in local minima in the DOS  and both electron- and hole-side SDPs  at this vHS. This is an analog of a spin angular moment of the electron. However, m(k) is orbital in nature, and it is responsible for the splitting between the K and K′ valley instead of the up- and down-spin. A general form of the m(k) is expressed as the following equation9:H(k) is the Bloch Hamiltonian, and ε(k) is the dispersion of band. We calculated m(k) for the band structure in Fig. m(k) with respect to the wavevector of the first, second, and third bands in the hole-side of the main DP, as depicted in Fig. m(k) is large for the gapped DPs, including both the main DP and SDPs3. Moreover, the calculation shows that there is a noticeably large m(k) presented at the second vHS. The second vHS(h) yields an m(k) value of 66 μB, corresponding to a valley g-factor of ~130. This value is noticeably large as an orbital magnetic moment of vHS, considering that m(k) is negligibly small at other vHSs such as Y-point in the first band , first vHS(h), and second vHS(h). The first vHSs on both the electron- and hole-side had previously been investigated25; here, we investigated the second vHS(h) which was observed27 but not discussed before. In addition to these, it is noteworthy that the Vind signal largely increases around nL = −4.65 × 1012 cm−2 in Fig. 2 dielectric.The two-terminal resistance Vind versus nL are measured in a magnetic field from B = + 0 to 2.23 T and results are shown in Fig. B , whereas the Vind signals from other vHSs, i.e., the first vHS(h) and the first vHS(e) , we present a comparison between the experimental values and the calculated DOS in aligned graphene/h-BN obtained from the continuum model12. In Fig. Vind as a function of nL and B plotted for +B and −B. The signals arising from three vHSs—the first vHS(e), first vHS(h), and second vHS(h)—are extracted from the data, and plotted with green, blue, and magenta solid circles, respectively in Fig. Vind data in high magnetic field region are presented in Supplementary Note n/n0 and B in Fig. E is also provided in Supplementary Note B-induced splitting of vHSs as well as the Landau fan diagram of the DPs were completely reproduced by the calculation. By plotting the K- and K′-valley contributions to the DOS separately in Fig. n/n0 value with the magnetic field. Furthermore, we plotted individual traces of Fig. Vind shown in Fig. To investigate the origin of the magnetic field-induced splitting in m(k) at the second vHS(h). To obtain a finite m(k) from Eq. 28  carbonate (PPC)-based dry release transfer method38, and the thickness of h-BN was chosen to be ~30–40 nm. Using e-beam (EB) lithography and reactive ion etching employing a mixture of CF4 and Ar gases, a trench was fabricated in the h-BN located between the two graphene flakes. Thus, the connection through h-BN between the two graphene flakes was eliminated. Finally, a contact pattern was created using an EB lithography with PMMA resist, and a 90-nm-thick Au/5-nm-thick Cr stack was deposited using EB evaporation. It should be noted that during device fabrication, the device was annealed at 350 °C under an Ar/3% H2 atmosphere after each flake transfer. This annealing caused the transferred graphene flakes to rotate within the plane toward the preferred orientation with respect to the adjacent h-BN40. In the device presented in Fig. h-BN, to generate moiré superlattice potential; however, the graphene on the right was not aligned.A device was fabricated using sequential dry release transfer of an individual flake. Two different flakes of monolayer graphene were successively transferred on top of the Iac = 10 nA, with a frequency of 18 Hz; the AC voltage was measured using a lock-in amplifier. A source measure unit (Keithley 2400) was used to apply constant power to the heater graphene.A liquid He-cooled variable temperature cryostat equipped with a superconducting magnet was used for transport measurement. The differential resistance of graphene was measured by applying an AC current Supplementary InformationPeer Review File


A novel graphene H-waveguide is proposed for active terahertz components. A graphene film illuminated by strong pumping light shorts the parallel conductor plates. The terahertz modes propagating along this film are amplified at certain conditions. A rigorous electromagnetic (EM) quasi-linear method of analytical calculations of  Today much attention is paid to two-dimensional materials and electronic components. Graphene is the first one consisting of carbon atoms and composing a flexible and stretchable honeycomb crystal lattice discovered by Geim and Novoselov . The there known ,5,6,7,8.The graphene sheets or strips can be placed over a dielectric substrate surface and combined with conductors forming the waveguides . The EM A part of graphene’s unique properties is its controllability by electric, magnetic, light fields, and chemical doping ,13. The Interesting techniques are when the real part of graphene complex conductivity njection ,19,20. Tic sheet , metal/gic sheet , conductic sheet , a dieleic sheet , and hybic sheet .The effectiveness of optically induced or charge injection lasing can be enhanced using the multilayered graphene ,25. For The nearest competitors to the graphene-based devices are the resonant tunneling diodes showing the amplification and generation of terahertz irradiation ,32. A prIn this contribution, a novel low-loss graphene-based waveguide  is propoThe terahertz range of frequencies is the place of complicated wave and material effects, and the development of new components is a challenging process . A part In microwaves, an H-waveguide consisting of two parallel conductor plates and a dielectric insert forming a figure of the letter H is known. The main mode of this waveguide is the quasi-TEM (transverse-EM) one  with Ey aveguide . This wain Refs. ,37,38,39In this paper, the central dielectric sheet of a nonradiative dielectric waveguide is substituted by a single or multilayered graphene film , the boundary conditions (4) and (5) at This expression gives a pair of forward and backward modes  whose prThe found longitudinal modal constant The Using (4), (5), (9) and (10), an analytical formula is derived for the modal propagation constants Similarly to the A graphene conductivity formula used here is from Refs. ,18(12)σThe zero position of quations  for charIn practice, according to the data of different authors, it is supposed that for the charge densities in order of –150 meV ,22,27. T devices . The gaiThe photo-induced carriers pump energy to traveling plasmons of the terahertz range, and the EM coupled-wave is amplified. This effect is approximately described by a graphene conductivity Formula (12) obtained using Kubo’s approach. In Ref. , it is sAnalyzing Formulas (8) and (11), it is seen that a critical frequency In The simulation of the imaginary parts of propagation constants shows that the negative conductivity effect makes these modes propagate with amplification occurring below and over their critical frequencies m)/k0)>0 . RemarkaAnother variant is when ed range . These wfilm see .As mentioned in y states . In grapuctivity . Below fsolution ,46,49,50Another mode marked as graphene . In thisFor comparison, consider the backward (0) mode  and calcThe imaginary part of the longitudinal propagation constant  is negatIn this way, other Concluding the research with the modes of different polarizations, it is seen that their interactions with graphene films highly depend on the modal type, as it was shown earlier in  in the rComing back to the An important question is on the controllability of amplification parameters. The modal parameters can be adjusted in part by dielectric filling. The increase in permittivity leads to some decrease in the phase z(1)/k0)  and lossonstants  as it fohe field  and the The proposed waveguide’s guiding properties’ overall review shows that all its complex It is worthwhile to notice that these results are obtained using the quasi-linear approach. Localization of the field close to graphene leads to increased field values, and if this field is strong enough, it influences the graphene conductivity. It limits the quasi-linear modeling’s applicability to the cases where amplification and signals are not so strong. In general, the problem should be formulated in its self-consisted nonlinear form and solved using, for instance, the iteration methods ,15. AnotAlthough the active graphene-based devices demonstrate an extremely high level of gain in order of 000 cm−1 , the queUsually, in terahertz frequencies, the conductor loss prevails the dielectric one. The loss level around 10–15 dB/mm is found below 10 THz, even in a parallel-plate waveguide for ing mode ,51.The conductor loss of complex modes below their cut-off frequencies is exceptionally high, and this worst-case scenario is studied below.The conductor loss constant tance Rs ,52,53,54tance Rs .An analytical formula used here to calculate the conductor loss constant The found propagation constant corrected by loss in conductor plates allows calculating the field components’ longitudinal dependence along the Overall review of the obtained results shows that the proposed structure can provide a very high gain of terahertz signals, similarly to the studied earlier planar structures. Still, the impact of many other factors should be additionally investigated in the future. Among them is the influence of nonlinearity ut loads ,32.In this paper, a novel guiding structure has been proposed for terahertz lasing applications. The waveguide consists of two parallel-plates of conductors shorted by a graphene film and composing an H-waveguide. The negative conductivity of graphene is induced by pumping light, and the THz modes are amplified propagating along with this structure. At the difference to known designs, the proposed waveguide can have decreased loss due to the complete exclusion of the sharp-edged conductors and graphene edged strips from its design and using the This waveguide has been analyzed in a quasi-linear regime using a rigorous EM method of field matching. The algorithm is formulated for the hybrid, The waveguide’s design can be enhanced further using the multilayered graphene conductors and heterostructures to increase pumping light absorption ,56. It hThe obtained results highlight the EM interaction mechanisms with graphene films showing the modal-type and mode-dependent amplification and irradiation in the studied open graphene-based structure. Based on our theory, a set of waveguides and components can be designed for the loss-compensated interconnections and active antennas. Self-oscillating devices can be developed by creating the active resonators in which the instability condition is provided by choosing the proper geometry of a proposed H-waveguide and loads .


FES1A leads to a defect in thermotolerance of Arabidopsis; however, independent fes1a mutants exhibit a range in the extent of thermosensitivity. Here, we found that BRF2, a gene adjacent to FES1A and encoding a component of transcription factor IIIB, affects the thermosensitivity of fes1a mutants. Knockout of BRF2 suppressed fes1a thermosensitivity, while overexpression of BRF2 increased thermosensitivity of fes1a. BRF2 in fes1a mutants regulates the transcriptional strength of RNA Polymerase II and accumulation of heat shock proteins and eventually affects the thermotolerance of fes1a. There is a cross-talking between RNA Pol III and Pol II. The cross-talking is initiated by BRF, magnified by the mutation of FES1A, and finally has an effect on thermotolerance.FES1A is a heat shock protein 70 binding protein. Mutation of  Plants are sessile organisms. To cope with high-temperature stress, plants have evolved various adaptive mechanisms to optimize their growth and development to ultimately achieve successful reproduction. Thermotolerance in plants is associated with a number of regulatory and functional genes which constitute complex signaling pathways. It has been found that abscisic acid, salicylic acid, ethylene, reactive oxygen species, membrane fatty acid composition, ubiquitin, heat shock proteins (HSPs), programmed cell death, and photooxidation are all involved in thermotolerance.Arabidopsis mutant shows a defect in thermotolerance  and a substrate-binding domain (SBD). ATPase activity is contained in the NBD. In the ATP-bound state, the SBD of HSP70 loosely associates with its substrates . Once ATtibility .Eukaryotic genes and RNAs are transcribed by three RNA polymerases. RNA polymerase (Pol) I and Pol II are responsible for transcribing rRNAs and mRNAs, respectively, while RNA Pol III transcribes tRNAs, 5S ribosomal RNAs, 7SL RNAs, RNase P, and U6 spliceosomal small nuclear RNAs . Genes tfes1a exhibited defects in thermotolerance but to different degrees . T-DNA insertions were confirmed using PCR and sequencing (quencing .ScBRF1-ΔN10 cDNA fragment (lacking the coding sequence for the first 10 amino acids) was cloned into pYX242WS ×2-pMY72. The PCR-amplified fusion fragment of BRF2-(HA)×2 .The cDNA of ® 480 (LC480) using the SYBR Green system. The gene specific primers used in the qRT-PCR analysis are listed in ACTIN8 gene was used as an internal control.Total RNA was isolated from 15-day-old seedlings using TRIzol reagent (Invitrogen). First-strand cDNA was synthesized using a PrimeScript™ RT Reagent Kit with a gDNA Eraser (Takara). RT-PCR was performed using the primers shown in Western blot was performed as described previously  using thP < 0.05).All experiments in this study were performed at least three times, and the values are expressed as the mean ± SD. Statistical significance was determined by Duncan's multiple range test  plants, finally perished, indicating that all fes1a mutants possessed thermotolerance defects, but with different sensitivities. In addition, the survival rates of the seedlings undergoing an acquired thermotolerance challenge indicated that fes1a-3 had the best thermotolerance among the three fes1a mutants, with the survival rate reaching 92.5%, while fes1a-2 and fes1a-1 had 41.7% and 0.8% survival, respectively , BRF2 (At3g09360), and BRF3 (At2g01280). We further bred the double mutants of BRFs. The homogenous double mutants of brf1 brf3 and brf2 brf3 were generated, while the double mutation of BRF1 and BRF2 led to sterility  of RNA Polymerase II largest subunit 1 (RPB1), using anti-S2P-CTD and anti-S5P-CTD antibodies. The CTD of RPB1 is composed of tandem heptad repeats that are critical for the activity of RNA Pol II  and the Research Fundamental Capacity Improvement Project for Middle Age and Youth Teachers of Guangxi Universities (2019KY0517). Research in the lab of DZ was supported by the National Science Foundation grant IOS-1322796 and the Research Growth Initiative (RGI). The funder had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.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.


Structural colorful cholesterics show impressive susceptibility to external stimulation, leading to applications in electro/mechano-chromic devices. However, out-of-plane actuation of structural colorful actuators based on cholesterics and the integration with other stimulation remains underdeveloped. Herein, colorful actuators and motile humidity sensors are developed using humidity-responsive cholesteric liquid crystal networks (CLCNs) and magnetic composites. The developed colorful actuator can exhibit synergistic out-of-plane shape morphing and color change in response to humidity, with CLCNs as colorful artificial muscles. Through the integration with magnetic control, the motile sensor can be navigated to open and confined spaces with the aid of friction to detect local relative humidity. The integration of multi-stimulation actuation of cholesteric magnetic actuators will expand the research frontier of structural colorful actuators and motile sensors for confined spaces. In contrast, structure color remains vivid under daylight and is free of photobleaching problems.Colorful outlooks have several benefits for living creatures, for example chameleons and octopi, in the purpose of camouflage, body protection, signaling, and physiology.–24 As a typical kind of photonic crystals, cholesteric liquid crystals consist of rod-like liquid crystalline mesogens and periodically align in a helical manner. Cholesterics reflect the light of certain wavelength following Bragg's Law: λ = npsinθ, where λ is the central wavelength of reflected light, n is the average refractive index of liquid crystals, p represents the pitch of cholesteric liquid crystals and θ is the incidence angle. Impressive progress has been made in the development of dynamic colorful cholesteric liquid crystal devices.–31 However, most of the previously reported devices were in the form of static coatings/liquid crystal glass cells or polymer film sheets with 1D in-plane shrinkage/elongation. Despite impressive reports on the dynamic color change of the humidity-responsive CLCNs, attention was mainly focused on the chromatic response of CLCN coatings adhered to substrates.–34 The mechanical deformation parameters of hygroscopic CLCNs that are critical for robotics remain unexplored, and 3D actuation remains rarely demonstrated. While for 3D actuators based on liquid crystal polymers,,35–43 the sample cutting direction couples with the deformation modes  since LC actuators usually adopted spatially non-uniform molecular configurations, e.g., radial/splay/twist-nematic alignment.–43 This coupling complicates the fabrication of the actuator with complex shapes and desired actuation modes. Such molecular configurations are also colorless and could not be directly used to develop colorful actuators.Most of the structural colors result from ordered microstructures, including scattering, thin-film interference, gratings, metasurfaces, total internal reflection, and photonic crystals.In the present study, we show the application of the humidity-responsive CLCN as a platform to develop colorful actuators with synergistic color change and shape morphing when the CLCNs act as colorful artificial muscles, and the control of actuators by humidity and magnetic field; we also showcase CLCNs' applications in robotic and motile sensing fields while CLCN coatings act as humidity sensors with the integration of magnetic actuation and aid of friction, since currently most of previously sensors were usually static. The aforementioned coupling between the actuation mode and actuator cutting direction is overcome by using cholesteric alignment where mesogens rotate along the helical axis/film thickness direction, which is accompanied by the benefit of endowing the actuator with structural color. We first utilize humidity-sensitive contractile CLCNs as colorful artificial muscles to develop structural colorful actuators with synergistic out-of-plane shape morphing and color change in response to external stimulus, i.e., humidity, and demonstrate the multi-stimuli robotic control using the magnetic field in addition to humidity. Specifically, we develop colorful actuators mimicking blooming flowers and butterfly flapping wings to show their synergistic shape morphing/color change performance under humidity and magnetic stimulation. We then show the application of magnetic actuation that could navigate motile sensors to different places and sense local humidity where commercial tethered sensors are not facile to implement.22.1p = 1/(HTP·c), where HTP and c are helical twisting power and concentration of the chiral dopant, respectively. Photoinitiator 7 (IRGACURE 369) was used to initiate photopolymerization while inhibitor 8  was used to prevent premature thermal-induced polymerization during sample processing. The compositions of monomers were optimized to afford a broad nematic phase and enable LCN to show wide color spectra change upon base treatment. To prepare LC films, the LC monomer mixture in isotropic phase at 80 °C was filled into the LC cell composed of two glass substrates with a gap of 20 μm that were coated with antiparallel-rubbed PVA. In the monomeric state, the cholesteric monomer mixture showed temperature-dependent optical reflection. The reflection band was red-shifted upon cooling  monomers . Humidity-responsive carboxylic acid groups-containing monomers .Here we employ cholesterics to break the coupling between actuation modes and cutting direction as the LC molecular long axis rotates along the helical axis in the thickness direction. The introduction of out-of-plane 3D actuation into structural colorful actuators provides opportunities for developing photonic devices with more degree-of-freedom. In detail, two CLCN films and magnetic Ecoflex  with NdFeB microparticles  were processed to form a triple-layer structure with the magnetic Ecoflex layer in-between . Firm inMaratus robinsoni. To empower humidity-responsive actuation, asymmetry was introduced into the actuator via base treatment of only one side CLCN of the CLCN/Ecoflex/CLCN composite. During actuation, the hygroscopic LCN layer expanded when exposed to moisture and resulted in shape change. Experimentally, the colorful stripe (dimension of 2 mm × 20 mm) curled in response to moisture and the color also synergistically changed; after stopping the moisture flow, the strip recovered its initial curling state. Simulation results also match well with the experimental phenomena  into a circular shape with the aid of a fixture propoxy)benzoic acid), 2 (4-((6-(acryloyloxy)hexyl)oxy)benzoic acid), 3 (4-methoxyphenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate, synonym RM105) and 5 -hexahydrofurofuran-3,6-diyl bis(4-((4-(((4-(acryloyloxy)butoxy)carbonyl)oxy)benzoyl)oxy)benzoate), synonym LC756) were obtained from Synthon Chemicals. LC monomer 4 propoxy)benzoate), synonym RM257) was purchased from Wilshire Technologies company. Chemical 6 , photoinitiator 7 (IRG369), inhibitor 8 (butylated hydroxytoluene), and poly (Mw 85–124 kDa) were purchased from Sigma-Aldrich. NdFeB microparticles  were purchased from Magnequench.Glass substrates were cleaned in acetone and n-isopropanol with ultrasonication for 10 min, and then treated with UV ozone for 20 min. PVA solution (3% PVA in water) was spun coated onto substrates at a speed of 1500 rpm for 45 s and then dried on a 120 °C hotplate for 30 min. The PVA-coated glass substrates were then rubbed with a cloth and assembled into liquid crystal cells with 20 μm spacers to determine the cell gap. The LC mixture consists of compounds 1–8 with the mass ratio of compound 1 : 2 : 3 : 4 :5 : 6 : 7 : 8 = 25 : 25 : 15 : 12 : 7 :15 : 1 : 0.5. The ratio of monomers was adjusted carefully to have a proper temperature range of cholesteric phase from 22 to 71 °C  and then treated with vinyltrimethoxysilane (2% in methanol) via spin-coating at a speed of 1500 rpm for 45 s. Then magnetic Ecoflex0030 composite (mass ratio of Ecoflex part A : part B : NdFeB microparticles : vinyltrimethoxysilane = 100 : 100 : 200 : 2) was sandwiched between two LCN films. The gap (thickness of magnetic Ecoflex) between LCN films was 300 μm determined using suitable spacers. The magnetic Ecoflex was cured at 95°C for 30 min. The triple-layered composite was carefully harvested from the glass substrate after soaking in water to dissolve the sacrificial PVA layer. LCN/Ecoflex/LCN sheets with predesigned shapes were fabricated with a laser cutter (LPKF ProtoLaser U3 Cutter).The walking robot robotic sensor was composed of three pairs of magnetic Ecoflex legs with a CLCN-coated PDMS body. Ecoflex (Part A + Part B) was thoroughly mixed with magnetic NdFeB microparticles, degassed in a vacuum chamber for 10 min, poured onto a plastic substrate and blade-coated into a film with a thickness of ≈300 μm, which was cured at 45 °C for 4 h. Magnetic legs were laser cut from the magnetic Ecoflex film and magnetized in the designed direction using MicroSense EZ7 vibrating sample magnetometer. To prepare the PDMS body, CLCN was plasma treated and coated with silane to form firm bonding with PDMS. A proper amount of PDMS (mass ratio of base: curing agent = 10:1) mixed with black dye  was poured onto the CLCN film sticking on a glass substrate. After curing in a 90 °C oven for 3 h, the composite was immersed in water to release the composite from the glass substrate by dissolving the PVA layer from the CLCN preparation step. To assemble the magnetic robot, the magnetic legs were glued onto the PDMS body with a small amount of Ecoflex as the glue.To fabricate the cylindrical magnetic robotic humidity sensor, uncured magnetic Ecoflex (Ecoflex: magnetic microparticles = 1:1 in mass) was injected into a plastic tube (inner diameter: 2 mm) and cured in a 60 °C oven for 4 h. After curing, the cylindrical magnetic Ecoflex was carefully pulled out from the plastic tubular mold. The cylindrical magnetic Ecoflex composite was cut into 3.5 mm long pieces and magnetized with a sinusoidal magnetization profile by confining the cylindrical Ecoflex rod in a circular fixture  with a temperature ramp rate of 10 °C minFinite element analysis (FEA) was performed using commercial software  to verify the deformation of the LCN/magnetic Ecoflex/LCN sandwich structure. Eight node hexahedral elements with reduced integration (C3D8R) were used to model the structures and included at least 8 elements along the width to accurately capture the bending deformation. The swelling of the LCN was predicted by using the analogy to thermal expansion. Orthotropic thermal expansion properties were defined for the LCN material and a temperature differential was applied to induce the swelling. The thermal expansion constants were found by experimentally measuring the shape change of LCN samples. Both LCN and magnetic Ecoflex were modeled as linear elastic materials and the elastic constants were found experimentally. The change in elastic modulus of LCN material due to NaOH treatment was incorporated by defining a temperature-dependent Young's modulus.A commercial humidifier was used to blow moisture to the humidity-responsive actuator. To investigate the responsive rate, moisture was applied to the colorful stripe in Supplemental MaterialsSupplemental Movie 1Supplemental Movie 2Supplemental Movie 3Supplemental Movie 4Supplemental Movie 5


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