This work establishes a facile and reliable route to fabricate graphene films with advanced and repeatable electrical properties, which is significant and essential for fair evaluation of CVD-grown graphene films and further practical applications.Graphene films grown by the chemical vapor deposition (CVD) method have attracted intensive attention due to their native advantages of both high quality and large quantity for commercial applications. However, previously reported graphene films have exhibited uncertain and conflicted electrical properties that greatly hinder them from being used to build reliable electrical devices because of incompatibility during the complex and multifarious transfer process. Herein, the relationship between the transfer parameters and electrical performance was systematically studied. It demonstrates that cracking during the transfer process causes significant loss of carrier mobility and hence an increase in sheet resistance. Additionally, unstable doping plays a key role in the carrier density and hence greatly influences the sheet resistance. By introducing HCl as a doping agent, graphene films with repeated sheet resistance of approximately 300 ohm sq Graphene films grown by the chemical vapor deposition (CVD) method have attracted intensive attention due to their native advantages of both high quality and large quantity for commercial applications. It was firstly reported by Samsung that large scale graphene films with sizes up to 30 inches were successfully fabricated using thermal release tape as an intermediate transfer layer, which made it possible to build an operable and useful touch panel.20 This impressive progress had attracted broad attention, but the difficulty of operation led to some conflicting results in the reports that followed. Pressure-sensitive adhesive films and silicone films have been used as improved intermediate layers to produce graphene films that exhibit more advanced completeness and electrical properties.26 Moreover, Sony Corporation produced a 100 m-long high-quality graphene transparent conductive films by roll-to-roll CVD and transfer with the assistance of UV-glue bonding.23 Undoubtedly, the correct selection of the transfer method plays a key role in determining the final device performance.11,27–29Various transfer methods have been developed to solve those problems, including the polymer-assisted transfer method,3),30 iron nitrate (Fe(NO3)3),31 or ammonium persulphate ((NH4)2S2O8).20 For instance, Youngsoo Kim et al. reported a monolayer graphene film with sheet resistance of 923 + 148 Ω sq−1 by transferring CVD-grown graphene with PMMA and etching a Cu substrate with 0.02 mol L−1 (NH4)2S2O8 solutions.32 For the same growth and transfer process, other studies revealed diverse results with the sheet resistance of graphene films of 1520 + 67.7 Ω sq−1.33 Similar phenomena appeared in other etching systems. Li et al. removed the Cu substrate using a 0.05 g ml−1 Fe(NO3)3 solution for 12 h and obtained graphene films with a sheet resistance of approximately 2100 Ω sq−1.34 However, the sheet resistance of graphene films from other reports was 425 Ω sq−1.35 Moreover, for the FeCl3 etching system, two studies reported the sheet resistance of graphene films as 510 Ω sq−1 and 725 Ω sq−1.36,37 After broadly reviewing current reports describing the transfer of graphene films, it is noted that the resultant graphene films have quite different electrical properties.In addition to the numerous transfer methods, another non-negligible and irreplaceable function comes from the etchant for removing catalyst substrates, which usually contains iron chloride . After reaching 1000 °C for 10 minutes, 30 sccm CH4 was introduced for 30 minutes to grow graphene on the Cu surface. Finally, the Cu foil with graphene on its surface was cooled to room temperature.Graphene films were synthesized through the traditional CVD method.24 PMMA method,31 TRT method20 and UV glue method.23 For the typical UV glue method, a Cu foil with graphene film on its surface was bonded onto PET film with UV glue . Subsequently, the epoxy was cured using a UV curing machine . Then, the Cu was etched by different etchants, including ammonium persulphate (NH4)2S2O8, iron chloride (FeCl3), and iron nitrate (Fe(NO3)3) solutions. Finally, the graphene/PET film was washed with deionized water several times to remove any etchant residuals and was then dried under an atmospheric environment.The CVD-grown graphene film on the Cu was transferred to a PET substrate through different approaches, including the PDMS method,The sheet resistance of graphene on a 5 cm × 5 cm square of PET was measured with a four-point probe  at room temperature. The sheet resistance mapping measurement was carried out with a sheet resistance mapping system . The morphology of graphene on the PET film was characterized by field emission-scanning electron microscopy  and atomic force microscopy . Raman spectra were obtained on graphene films transferred by the PMMA-assisted method using a Renishaw microspectrometer with a laser wavelength of 514 nm. X-ray photoelectron spectroscopy (XPS) measurements were performed using a Kratos Axis Ultra delay-line detector (DLD) spectrometer . The Hall Effect Measurement System (HALL 8800) was used to measure the carrier mobility and carrier density of graphene film with 7200 magnetic strength.3.−1, 1181 ± 178 Ω sq−1, 565 ± 70 Ω sq−1, and 467 ± 50 Ω sq−1, respectively for the PDMS, TRT, PMMA, and UV-glue methods using the same etchant with 0.2 M (NH4)2S2O8. It is well-known that the electrical conductivity is primarily determined by two physical parameters: carrier mobility and carrier density. Here, the detailed electrical properties are presented in 12 cm−2. It different from the carrier density, the carrier mobility of different samples will exhibit a huge gap. It can be seen that the carrier mobility of graphene transferred by the UV-glue method reaches the highest value of approximately 1800 cm2 V−1 s−1, which is six times higher than that of the PDMS method. These results clearly demonstrate that the large difference in sheet resistance originates from the change in carrier mobility while changing the transfer process.21,38 Here, the brighter area might suggest that a poor electrical connection exists, which is due to the cracks that occur during the transfer process. The block of electrical connection would greatly influence the carrier transport and hence decrease the carrier mobility. For comparison, the SEM image of the UV-glue sample is quite uniform on the entire surface with slight wrinkles, which suggests improved carrier mobility. Thus, the final sheet resistance can be significantly different for samples prepared by different transfer methods. AFM measurements were also performed to analyze the microstructures of transferred graphene films, such as ripple or domain boundary,39,40 as shown in the insets of Because the graphene films on Cu foil are fabricated through exactly the same CVD process, it is quite necessary to investigate the resultant graphene films on PET in detail to further understand their nature. As shown in 4)2S2O8, FeCl3, and Fe(NO3)3 solutions, the sheet resistance of the graphene films gradually decreases as the concentration of etching solutions was increased. Among these three etchants, the graphene films etched in (NH4)2S2O8 exhibited the corresponding lowest sheet resistance. The carrier density and carrier mobility of these samples were investigated in detail, and as shown in 4)2S2O8 presents the highest value among these three etchants. In contrast, the carrier density of these graphene films increased significantly as the corresponding etchant concentration increased, as shown in 4)2S2O8 is lower than that of the other samples, the lower sheet resistance is still realized in graphene films etched in (NH4)2S2O8, which originates from the large enhancement of carrier mobility. It can be concluded that an increase in ion concentration may not affect the carrier mobility, which remains with an unchanged electrical connection, but greatly enhances the carrier density and hence reduces the sheet resistance.The electrical performance of graphene films using different etchants with the same UV-glue transferring method is compared in 20,41,42 During the above studies, it was found that the pH value decreases as the etching process proceeds. Thus, H+ ions as dopant were systemically studied herein to determine if this could further improve graphene films. 4)2S2O8 solution plus different acids. The sheet resistance of graphene films generally decreases as the concentration of additional acids increases. For HNO3 and H2SO4 as dopants, the carrier mobility of graphene films remains smooth while the corresponding carrier density increases as the concentration of acids increases, which leads to an overall decrease in sheet resistance. The lowest sheet resistance was realized in (NH4)2S2O8 etchant with 1.2 M HCl. With increasing HCl concentration, the sheet resistance sharply increased, and with HNO3 and H2SO4, the carrier mobility of samples in HCl linearly decreased. With careful observation as shown in −1. Sheet resistance mapping measurements were also performed to reveal the exact electrical performance of 5 cm × 5 cm graphene films by detecting eddy current signals, as shown in 4)2S2O8 etchant exhibits complex color units over the entire sample, which indicates the quite disordered distribution of sheet resistance in the range of 350–700 ohm sq−1. After adding different acids, the sheet resistance was significantly reduced, and the homogeneity of the sheet resistance was greatly improved with much more uniform color distribution. Among these three types of acids, the sample with the addition of HCl exhibited the lowest sheet resistance, of approximately 300 ohm sq−1. These results are consistent with the four-probe measurements and Hall effects measurements.Based on the above analyses, to further improve the electrical conductivity of graphene films, it is very important to find a method that will increase the carrier density without the loss of carrier mobility. This requirement can be satisfied by introducing dopant during the transfer process, and this has been broadly studied.4)2S2O8 etchant exhibited lower sheet resistance compared to that of FeCl3 and Fe(NO3)3 etchants, which is derived from the contribution of higher carrier mobility. With the addition of HCl as a doping agent, the carrier density of samples in (NH4)2S2O8 etchant plus HCl becomes more uniform in the range of 2000–2400 cm2 V−1 s−1 compared to a broad range of 1300–2500 cm2 V−1 s−1 for samples in bare (NH4)2S2O8 etchant. The corresponding carrier density of samples in the (NH4)2S2O8 etchant plus HCl is also significantly improved in a narrow range of 9–12 × 1012 cm−2 compared to 4–10 × 1012 cm−2 for samples in bare (NH4)2S2O8 etchant. Thus, the sheet resistance of graphene films using HCl dopant reaches the lowest value of approximately 300 ohm sq−1 and is also in a much narrower range of 270–380 ohm sq−1 compared to the broad range of 350–700 ohm sq−1 for the graphene films treated with bare (NH4)2S2O8 etchant. This demonstrates that the sheet resistance of graphene films can be repeatedly realized in a quite narrow range using (NH4)2S2O8 etchant plus 1.2 M HCl dopant. For the original graphene films, the G peak is at approximately 1582 cm−1 and the D band is at approximately 2700 cm−1. The doped graphene will exhibit an upshift of the G band and 2D band.43–463)3 and FeCl3 is slightly upshifted compared to that of the (NH4)2S2O8 sample, which is consistent with the carrier density action in −1 in graphene films using (NH4)2S2O8 etchant plus 1.2 M HCl dopant, which is also of the highest carrier density and hence lowest sheet resistance. PBM data was replaced with SVG by xgml2pxml:<glyph-data id="z.dbd" format="PBM" resolution="300" x-size="8" y-size="10" xml:space="preserve">00000000000000000000000000000000111111110000000011111111000000000000000000000000</glyph-data><svg xmlns="http://www.w3.org/2000/svg" version="1.0" width="13.200000pt" height="16.000000pt" viewBox="0 0 13.200000 16.000000" preserveAspectRatio="xMidYMid meet"><metadata>Created by potrace 1.16, written by Peter Selinger 2001-2019</metadata><g transform="translate scale" fill="currentColor" stroke="none"><path d="M0 440 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z M0 280 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z"/></g></svg>O, respectively. For the p-doping of graphene films, the C 1s peaks corresponding to the sp2 and sp3 hybridized states were shifted to lower energy,20,47 which is similar to the case for p-doped carbon nanotubes.48 The peaks at 288.372 eV, 289.049 eV, 289.084 eV, and 289.097 eV correspond to the CO peaks for graphene films using (NH4)2S2O8 etchants plus HCl, FeCl3 etchants, Fe(NO3)3 etchants, and (NH4)2S2O8 etchants, respectively. The CO peak is obviously redshifted by 0.73 eV, and the C–C peak is redshifted by 0.16 eV after the addition of HCl dopant in (NH4)2S2O8 etchants, which is consistent with the Raman results.To further study the doping effect of different etchants, XPS measurements were also carried out, as shown in 4.−1 with a narrow range if a (NH4)2S2O8 etchant with 1.2 M HCl dopant is used. This work provides a facile and reliable technique to obtain graphene films with advanced and repeatable electrical properties, which is critically important for the fair evaluation of CVD-grown graphene films and also the practical application in the field of electrical devices.In summary, the relationship between the electrical properties of graphene films on PET substrate and the transfer parameters has been systematically investigated in detail. It was found that the guarantee of electrical connections is closely related to the carrier mobility. Additionally, the selection of etchant and dopant is very sensitive to the carrier density and hence influences the sheet resistance. Finally, graphene films can repeatedly reach a low sheet resistance of approximately 300 ohm sqThere are no conflicts to declare.


Compared with graphene oxide ink/gel/resin based manners, laser‐induced graphene (LIG) is unique for facile and scalable assembly of 1D and 2D structures but still faces size and shape obstacles for constructing 3D macrostructures. In this work, a brand‐new LIG based additive manufacturing (LIG‐AM) protocol is developed to form bulk 3D graphene with freeform structures without introducing extra binders, templates, and catalysts. On the basis of selective laser sintering, LIG‐AM creatively irradiates polyimide (PI) powder‐bed for triggering both particle‐sintering and graphene‐converting processes layer‐by‐layer, which is unique for assembling varied types of graphene architectures including identical‐section, variable‐section, and graphene/PI hybrid structures. In addition to exploring combined graphitizing and fusing discipline, processing efficiency and assembling resolution of LIG‐AM are also balanceable through synergistic control of lasing power and powder‐feeding thickness. By further studying various process dependent properties, a LIG‐AM enabled aircraft‐wing section model is finally printed to comprehensively demonstrate its shiftable process, hybridizable structure, and multifunctional performance including force‐sensing, anti‐icing/deicing, and microwave shielding and absorption. In this work, a laser‐induced graphene based additive manufacturing (LIG‐AM) is developed to print bulk 3D graphene with freeform shapes such as identical‐section, variable‐section, and graphene/PI hybrid structures. By investigating particle‐sintering and graphene‐converting dual‐mechanism as well as process dependent properties, an aircraft‐wing section model is finally printed to demonstrate its shiftable process, hybridizable structure, and multifunctional performance. As one of the most promising nanotechnologies, graphene has attracted tremendous attention for assembling smart devices and structures with various geometries from 1D to 3D based on its hexagonal‐latticed molecules, embeddable/connectible/modifiable 2D nanostructures, as well as extraordinary electrical, mechanical, thermal, and optical properties. For example, graphene‐enabled 1D filaments, fibers and yarns, 2D thin films, papers and fabrics, and 3D foams, hydrogels, and millispheres have been explored extensively by endowing the assembled macrostructure with free‐standing skeletons, hierarchical microporosities, ultralow density, and interconnected high‐conductive networks for enabling critical components in wearable electronics, thin‐film batteries, artificial skins/muscles, biomimetic robots, self‐sensing composites, etc.Nowadays, 3D printing has become the most powerful technology for rapid designing, prototyping, and manufacturing structures, components, and products with multidimensional geometries and random complexities in almost all industries.1, 2 and Shi et al. respectively grew graphene on macroporous nickel and seashell templates to form freestanding foam‐like structures with the size of 20 × 20 × 2 mm3 after the etching process. Without introducing issues of high temperature and rigorous atmosphere control, Xu et al. and Yu et al. respectively applied hydrothermal and directional‐freezing approaches to cast and reduce GO suspension into self‐assembled graphene hydrogels or aerogels with the cylinder‐shaped volume around 9 cm3. Although bulk formation strategy could reach centimeter‐scaled architecture, it is unable to achieve arbitrary shapes due to the lack of programmable working path. As an advanced alternative, layer‐by‐layer assembly relies on computer‐aided process to create 3D graphene monoliths or patterns through different additive manufacturing manners including inkjet printing, extrusion printing, stereolithography, kirigami patterning, etc. With the feature size of micron scales, for example, Hensleigh et al. and Jiang et al. respectively applied photocurable GO resin and GO sol‐gel ink to print self‐standing 3D graphene structures with programmable microlattices. The layer‐by‐layer based methods could certainly promote the complexity and designability of structures; nevertheless, most of them rely on GO based inks, gels and resins as raw printing materials, still facing two major drawbacks. Firstly, the GO wet chemistry requires complex processing steps from suspension preparation, layer‐by‐layer stacking, freeze‐drying, to various chemical/physical treatments that dramatically prolong the working period and limit the size scalability. Correspondingly, the quality control in each step is tricky for tackling ink stability, printing rheology, GO reduction, structural shrinkage, etc. These further intensify the molding difficulty and part‐to‐part variations. Thus, a new 3D printing strategy toward swift assembly, freeform structuring, and ease of quality control is highly anticipated for construction of graphene macrostructures.To manufacture macroscopic graphene ensembles, two processing strategies have been applied majorly including bulk formation and layer‐by‐layer assembly. The former relies on non‐printing processes to either synthesize graphene on 3D porous metal templates or hydrothermally treat graphene oxide (GO) dispersion to form bulk foam structures. For example, by using chemical vapor deposition (CVD) protocol, Cheng et al.21 and By avoiding complexities of ink and catalyst preparations in traditional liquid‐assembling and CVD methods, LIG indeed has reflected its facile, low‐cost and scalable advantages for fabricating various single‐layered structures including graphene fibers, thin films, papers, and surface patterns, which have become core elements in various novel structures and devices, e.g., functional composites, supercapacitors, heaters, environmental, and biological devices. For assembly of macroscopic 3D objects, although several initial trials have emerged, LIG has still faced clear obstacles. For example, Luong et al. developed automated laminated object manufacturing (LOM) to fabricate centimeter‐sized graphene monoliths by repeatedly converting, fusing and milling Kapton films into stacked LIG layers with different shapes. With similar strategy, our group applied hot press to one‐step molding multiple pre‐impregnated LIG/epoxy papers to form 3D‐lamiated graphene composites with the size as large as 20 × 20 × 0.2 cm3. Although macroscopic dimensions are achievable, the above works require specific binding, milling, and/or 3D‐molding processes which have restricted the bulk formation of graphene with simple shapes. By raising a binder‐free strategy, Sha et al. applied sucrose and nickel particle mixtures as carbon source and catalyst to grow graphene layer‐by‐layer on the metal template. Although it is able to construct 1 × 1 × 0.8 cm3 sized foams, the post template‐etching treatment inevitably causes considerable volume shrinkage that confines the shaping accuracy. Other strategies such as LIG processed on preprinted 3D plastics, composites, and kirigami/origami patterns are also not able to construct freeform graphene structures. Thus, a novel LIG process toward the ease of freeform manufacturing of graphene 3D macrostructures is still not appeared.As a newly‐developed technique, laser‐induced graphene (LIG) has dramatically promoted the possibility of graphene assembly by introducing multiple unique characteristics including direct laser scribing, one‐step graphitic conversion, various compatible precursors, and customizable working routes.39 By Following this line of thought, in this work we developed a brand‐new LIG based additive manufacturing (LIG‐AM) protocol to form bulk graphene structures with freeform geometric shapes. Without introducing extra binder, template and catalyst, polyimide (PI) powder was applied as the only raw materials for both particle‐sintering and graphene‐converting purposes to construct 3D solids. Based on computer‐aided laser‐irradiation scribing to selectively process each layer with individually programmed slicing pattern, LIG‐AM is able to analogize the commercial selective laser sintering (SLS) technology to form varied types of bulk architectures including identical‐section, variable‐section, and even unique graphene/PI hybrid structures with random shape complexities. In addition to investigate the combined graphitizing and fusing discipline toward macroscopic assembly, systematic work has also been done to balance the processing efficiency and assembling resolution that are controlled interactively by laser power and powder‐feeding thickness. By further studying the tunable electrical, mechanical, piezoresistive, liquid‐sensing, and joule‐heating properties as well as resin‐integration reinforced strength and stretchability, a LIG‐AM enabled aircraft‐wing section model was specifically designed to comprehensively demonstrate its shiftable printing strategy, hybridizable structure, and multifunctional performance including multidirectional force‐sensing, anti‐icing/deicing, and microwave shielding and absorption.22.1Figure2 laser system serves as the power source to selectively solidify and graphitize the very top layer of powder bed with a preprogrammed slicing pattern before feeding a new layer to finally construct a printed 3D object. To specify, a thin layer of PI powder is firstly fed onto the working plate using a spacer to control the height of powder bed. Then, the laser irradiates and scribes the powder bed to selectively sinter and convert PI powder into a continuous graphene structure with specific surface pattern. Subsequent to the first LIG layer formation, a new powder layer is fed on top and followed by another irradiation process. The feeding and irradiating steps then repeat multiple times until processing all layers to present the entire structure after removing unprocessed powders.Inspired by the commercial SLS manufacturing to print 3D metallic, ceramic, and polymeric objects through layer‐by‐layer fusion of powders, the idea of using compatible powder‐based LIG raw materials is the key for constructing graphene macrostructures with freeform geometric shapes. In this work, commercially available thermoplastic PI powders with the size of ≈10 µm was selected as the ideal raw materials by competing other LIG‐compatible powders considering irradiation energy, degree of graphitization, and shape accuracy , the macroscopic LIG structure is no longer mechanically stable with considerable voids observable in the fibrous microstructure, indicating excessive ablation effect to destroy the LIG framework. More detailed scanning electron microscopy (SEM) images are displayed in Figure Based on mechanism analysis, it is reasonable to believe that the level of irradiation energy is the key to control the dual functionality of PI for both particle sintering and graphene conversion. Figure e layers.54 By  Raman spectroscopy in Figure IG/ID) and 2D to G (I2D/IG) peaks follow similar trend that the sample processed around 1 W shows both the highest IG/ID (1.37) and I2D/IG (0.41), indicating the best graphene quality with the fewest number of layers. Additionally, X‐ray diffraction (XRD) in Figure  Similarly, X‐ray photoelectron spectroscopy (XPS) in Figure In addition to optical and SEM analyses, a series of structural characterizations were further explored to support the process dependent graphene conversion. In contrast to 0.625 and 3.75 W processed samples, transmission electron microscopy (TEM) images in Figure 41 Ram2.2FigureL1) shows the fused PI structure, indicating that the transported energy is not high enough for graphitization. Accordingly, a dense LIG layer (L2) appears right above the PI layer indicating a proper energy for graphene conversion. It is also observed that fiber‐like structures are protruded out of the LIG surface to form a rather loose layer (L3), which is explained by the quick liberation of pyrolysis gases during the photothermal reaction to distort the LIG structure. According to soft nature of L3, it will merge with the new feeding layer to receive another irradiation treatment  should be critically controlled. Intuitively, LF should be smaller than L2 to ensure all new powders to be converted to graphene; otherwise, L1 and even unfused PI would appear to destroy the structural integrity. Along with the maximum thickness, the feeding layer LF also cannot be too small for causing too much thermal impact. Figure LF from 10 to 90 µm. Clearly, only when LF lies between ≈40 and ≈70 µm, uniform multi‐layered LIG can be formed; when LF < 40 µm, LIG shows both macroscopic and microscopic defects indicating strong ablation effect; when LF > 80 µm, clear delamination has been observed indicating the loss of interfacial bonding. Thus, by applying 50 µm as the proper LF, Figure LF for every processible condition of laser. Obviously, weaker/stronger laser power is compatible with thinner/thicker LF, indicating lower/higher processing efficiency but better/worse assembling resolution. To further support this, Figure LF while the second one chose precise process by using 1 W laser and 50 µm LF. Although the second one took longer time (4 h and 240 layers vs 1 h and 60 layers), it shows a much smoother surface with better graphitized structure.Thus, to construct full graphene objects through multi‐layer processing, the thickness of every powder‐feeding layer  and compressive strength (7.9±0.5 MPa) and LIG/Ecoflex composites with improved fracture strain (230%). Similarly, LIG‐AM structures reflect an ascending trend on both of their in‐plane (22±1.3 to 46±2.1 S m−1) and through‐plane electric conductivity (2±0.1 to 3.2±0.12 S m−1) as the increase of processing power  when subjected to cycled deformations along both tensile and compression directions, exhibiting the linear strain‐induced resistance change with high reproducibility. As the increase of laser power, the increasing trend of both tensile‐deformation determined (3.1±0.1 to 6.4±0.6) and compressive‐deformation determined gauge factor (78±2.4 to 96±2.3) indicates that higher power processed LIG‐AM structures are more sensitive to external disruptions, which coincides with previous finding that high irradiation could induce large numbers of microfissures/cracks in the conducting network. In addition to deformation sensing, the porous networks also endows the graphene structures with liquid‐sensing capability. Figure R/R0 = 1.8%) to 8 µL (maximum ΔR/R0 = 30.5%). The inset plot reveals the resistance‐change cycles with processes of fast rise and gradual recovery, relating to dynamic change of liquid rinsing and evaporation. By virtue of electrothermal characteristics, Figure  Other functional properties, including hydrophobicity, oil absorption, supercapacitance, and microwave shielding and absorption, were also evaluated and discussed in Figures By understanding the printing discipline for constructing freeform structures, processing dependent properties of LIG‐AM enabled 3D graphene were further investigated. By using a high‐precision balance for density determination, r Figure , confirmr Figure . The insAttributed to freeform 3D construction, selective graphene formation, as well as tunable multifunctionality, the proposed LIG‐AM could become a rather powerful 3D printing protocol for designing, developing and manufacturing various structures, components, and devices for meeting the need of multi‐scenario applications. Figure FigureR/R0) measured by horizontal electrodes varies accordingly depending on the force direction. Specifically, forces from horizontal directions (0° and 180°) introduce minimum ΔR/R0 around 58% and forces from vertical directions (90° and 270°) introduce maximum ΔR/R0 around 105%. Other forces introduce moderate ΔR/R0 depending on the specific angle. Secondly, the smart leading edge  has reached 44.7 dB for the smart skin with 2.5 mm thickness, which exceeds the SETotal of commercial EMI shielding materials (20 dB) and other reported LIG (24.8–32 dB). Besides, the smart skin with a nickel treatment has shown much improved reflection losses (RL) with −15.3 dB absorption peak at 9.1 and 2.5 GHz bandwidth (from 8.0 to 10.5 GHz) under −10 dB, representing that 90% of the electromagnetic wave energy has been absorbed. Along with detailed information in Figure Total and RL has proved the possibility of LIG‐AM technology for EMI shielding and stealth.To demonstrate a specific example for fully exhibiting various unique advantages of LIG‐AM, an aircraft‐wing section model with integrated smart graphene structures was designed, printed and tested. As displayed in e Figure  was desie Figure  with tun3In summary, we demonstrated a brand‐new LIG‐AM protocol to form bulk 3D graphene with freeform structures without introducing extra binders, templates and catalysts. By triggering both particle‐sintering and graphene‐converting processes layer‐by‐layer, LIG‐AM creatively irradiates PI powder‐bed to assemble varied types of graphene architectures including identical‐section, variable‐section, and unique graphene/PI hybrid structures with random shape complexities. In addition, processing efficiency and assembling resolution of LIG‐AM are also balanceable through synergistic control of lasing power and powder‐feeding thickness. By virtue of outstanding processing advantages, a series of LIG‐AM enabled smart devices/structures, especially the LIG‐AM enabled aircraft‐wing section model, are successfully printed and demonstrated their multifunctional properties to meet the need of potential multiscenario applications.42 laser with wavelength of 10.6 µm and a controlled XYZ‐movement was used for irradiating polymer powders . Typical values of laser power were varied from 0.25 to 5 W with the pulses per inch (PPI) fixed at 500 and the scribing speed at 50 mm s−1. The powder spreader  with the resolution of 10 µm was employed to control each layer thickness. After layer‐by‐layer printing, diverse LIG‐AM enabled graphene architectures were performed under ambient conditions.A laser platform  equipped with a CO−1 under argon atmosphere. Differential scanning calorimetry (DSC) tests were evaluated with TA Q5000IR instrument at a ramping rate of 10 °C min between 40 and 400 °C. Specific surface area was measured with a Quantachrome 2000e BET surface analyzer.SEM was performed with JEOL JSM 7001F at 10 kV to examine the morphologies of various samples. TEM images were taken with a high‐resolution JEOL 2100F operated at 200 kV. Raman spectra were collected with a Horiba HR800 Raman microscope using a 532 nm laser with a power of 5 mW. XRD characterization was performed on Rigaku D/max 2550. XPS measurements were performed with a Thermo ESCALAB 250XI instrument equipped with the energy standard of C1s = 284.8 eV binding energy for charge correction. Thermogravimetric analysis (TGA) was carried out with a NETZSCH STA 449F3 instrument at 10 °C minMechanical properties were evaluated through a dynamic mechanical analyzer  and an E44.104 tensile machine (MTS Systems). Electrical conductivity was quantified using a Keithley 2450 Sourcemeter. Joule heating temperature was monitored by a FLIR camera with the input DC current provided by a Keithley 2260 power source. Supercapacitive properties were collected by CHI608E electrochemical workstation. Microwave shielding/absorption properties were measured by Vector Network Analyzer  at room temperature. Water contact angles were obtained by water drop angle tester (OCA15 Pro).3) were carried out by a mechanical–electrical coupling method at a rate of 2 mm min−1 and the gauge factor (GF) was calculated by the equation GF = (R − R0)/(R0 × ε), where R, R0, and ε are instantaneous resistance, initial resistance, and strain, respectively. Liquid‐sensing tests of 3D graphene sensors (10 × 10 × 2 mm3) were applied by monitoring the real‐time resistance change through dripping microvolume acetone from 0.5 to 8 µL. Electrothermal tests of 3D graphene heaters (10 × 10 × 2 mm3) were performed by loading electrical input powers ranging from 0.25 to 2 W and deicing test of smart leading edge was conducted by recording the volume change of ice cube with the input power of 1.2 W. 3D graphene based‐supercapacitors (10 × 10 × 2 mm3) were fabricated using a three‐electrode system with 1 m H2SO4 electrolyte, where the counter electrode was a Pt wire and the reference electrode was Ag/AgCl. Adsorption capacity tests of 3D graphene removers for organic solvents and oil were calculated by the ratio between the maximum adsorbed adsorbate quantity M and the original mass m using the balance analyzer. High‐temperature resistance test of smart skin was implemented by observing the structural integrity under an alcohol lamp burning. Ni decorated LIG (LIG/Ni) was obtained by pulse electrodeposition in a standard three‐electrode system controlling the deposition time for 10 min. Electromagnetic waves shielding and absorbing tests of LIG and LIG/Ni microwave absorbers were carried out by waveguide method and coaxial wire method for S‐parameters and EM parameters (complex permittivity and complex permeability), respectively.By integrating Ecoflex0030  or epoxy resin , LIG/Ecoflex and LIG/epoxy composites were prepared respectively after the curing process at 60 °C for 6 h. Mechanical‐sensing tests of smart composites (30 × 10 × 2 mmThe authors declare no conflict of interest.Supporting InformationClick here for additional data file.Supporting Video 1Click here for additional data file.Supporting Video 2Click here for additional data file.Supporting Video 3Click here for additional data file.Supporting Video 4Click here for additional data file.Supporting Video 5Click here for additional data file.


Ab Initio Molecular Dynamics (AIMD) simulations to study graphene island alignment evolution at two temperatures. The results shed light on our experimental observations and those reported in the literature and point to the effectiveness of controlled thermal cycling in producing high quality graphene sheets on transition metal catalyst surfaces.Repeated thermal cycling by using an organic precursor is shown to be a successful technique for growing graphene on metal substrates. Having control on this process is of vital importance in producing large areas of high quality graphene with well-ordered surface characteristics, which leads us to investigate the effect of temperature on the microscopic mechanisms behind this process. Apart from being an important factor in the dissociation of the organic precursor and promoting the reactions taking place on the surface of the catalyst, temperature also plays a major role in the structure of the catalyst surface. First, we used eight thermal cycles to successfully grow graphene on the surface of Cu (111). Then, we employed  Repeated thermal cycling by using an organic precursor is shown to be a successful technique for growing graphene on metal substrates. Of these methods, mechanical exfoliation, although capable of producing high quality graphene on small scales, is the least scalable and appropriate method for electronics applications and mass production where larger areas of graphene are required, whereas the CVD method, typically catalytic, has emerged as the most powerful and dominating method in the industry.8,9Graphene, a single atomic layer of graphite and the building block of carbon nanotubes, has been proven to possess many unusual properties such as extraordinary chemical and optical characteristics, tensile strength and thermal and electrical conductivity that find applications in many areas such as ultrathin membranes, plasmonics, high-end composite materials and electronics.3 Growth mechanism on these substrates are shown to be highly dependent on temperature.10 Among these substrates, copper has become one of the most widely used catalysts for the synthesis of graphene using the CVD method. Large high-quality graphene films were grown on copper, which exhibit transferability and unique plasmonic characteristics.2,11,12 Low carbon solubility13,14 and weak Cu–C interactions15,16 along with low surface diffusion energy barrier of C atoms on Cu17 all contribute to surface-driven mechanisms present in the nucleation and growth of graphene domains.3,18–20 These factors may also explain why Cu produces predominantly single layer graphene.3,21 Low surface diffusion energy barrier contributes to highly mobilized carbon atoms that can travel freely on the Cu surface and attach to existing graphene islands. Note that surface Cu atoms have high mobility at high temperatures which can facilitate the mobility of C atoms and graphene islands at such temperatures and lead to defect healing.20,21 Therefore, surface morphology of Cu substrate at elevated growth temperatures is an important issue.Ni, Ir and Cu are three of the most common transition metals that are used as catalyst substrate for graphene growth.et al. investigated how the type of organic precursor may have effect on graphene growth and dictate its structure.22 Ethylene, acetylene and methane are organic precursors that are widely used as the source gas of which methane is known to require higher temperatures to decompose on the Cu surface. Ethylene23 and acetylene,24 on the other hand, has shown to produce continuous graphene coverage at considerably lower temperatures. In other studies, environmental conditions such as temperature, pressure and hydrogen that may have effect on graphene growth were investigated.10,25,26 The copper catalyst surface has also been subject to many studies as the surface plays a major role in the epitaxial graphene growth and achieving a perfectly clean surface prior to growth is highly desirable.27–30 Yu et al. reported their simple approach of preparing the copper surface by growing it on single-crystal sapphire. The resulting copper layer is reported to be extremely flat, chemically clean and can be easily peeled off to use for graphene growth. The graphene grown on such a copper surface exhibited very large domain sizes.31Reported research aimed at improving the quality of graphene grown over Cu surface were focused on several aspects of this process. As an example, Wassei 3,18 In the surface-driven mechanism of growth on copper, it is shown that graphene islands grow when temperature is high enough to facilitate the diffusion of islands. At such temperatures some islands may ‘stitch’ together to form larger graphene domains.32–36 Consequently, the overarching hypothesis is that defects observed in the graphene overlayer arise from the misalignment of graphene islands constituting a domain; various islands nucleate and grow with different rotational alignments across the catalytic substrate. Several studies have been aimed at investigating what dictates these island orientations. Studies in this area have concluded that domain shapes and sizes themselves are controlled by growth conditions such as temperature.37,38 Upon closer examination, two possible routes have been identified that would lead to the transition of islands to domains; either the islands migrate and coalesce into larger islands, or islands progressively grow in size and form domains through addition of C atoms.35,39,40 In the former, with the foregoing discussion, temperature would have great influence on rotation and migration of islands and domain growth, as well as on nucleation density, as evidenced earlier.38,41 While in the latter case, surface diffusion of C adatoms would be most likely to have a greater impact on growth of domains. Thus, the identification of the prevailing case will help in optimizing growth parameters. Although this may be a challenge since many factors are involved in the competition including carbon source gas decomposition rate, nucleation rate, surface diffusion and growth rate from carbon adatom addition.High resolution electron microscopy provides valuable insights into defects and domain (grain) boundaries in graphene produced from the CVD method. These domain boundaries have been subject to intense studies and may hold the key to understanding the growth mechanism. Two main mechanisms have been proposed for the growth of graphene on transition metal surfaces: segregation growth , and surface growth (Cu).ab initio methods, we investigate how temperature and time cycles  may affect the alignment between the Cu lattice and a pre-existing graphene fragment. Our focus is to study the interplay of the Cu substrate and the graphene overlayer in conjunction with temperature at early stages of growth.In this paper, our particular interest is to understand the role of nucleation and growth parameters, such as temperature, on graphene domain orientation. In this regard, the catalyst surface may have a more active role than thought in the determination of domain boundaries. In the present work, using experimental and −10 mbar) equipped with a variable temperature scanning tunneling microscope  chamber, and a separate preparation chamber, which includes an ion sputter gun for sample cleaning, a LEED (Low Energy Electron Diffraction) system, and a directional gas doser. The Cu (111) single crystal  was polished on one side and mounted on a standard tantalum sample plate from Omicron with an 8 mm diameter hole on its rear end to facilitate electron bombardment heating. Cu (111) was cleaned by 8 cycles of sputtering  and annealing . Temperature above 600 °C (873 K) was monitored by a pyrometer . Successful cleaning of the sample was confirmed by STM and LEED. Large continuous graphene islands were produced on Cu (111) surface through exposing the clean Cu (111) substrate to 1 × 10−5 mbar C2H4 at room temperature for 5 minutes, with subsequent annealing at 1000 °C (1273 K) for 5 minutes. This cycle was repeated 8 times.64 Successful graphene preparation was confirmed by scanning tunneling microscopy (STM). All STM images were collected at room temperature by using electrochemically etched W homemade tips with a sample bias of 0.7 V and a constant tunneling current of 0.4 nA. All the post annealing images were generally acquired 2 hours after the experiment to ensure that the sample had returned to room temperature. To ensure that the images shown here are consistent across the crystal face, for any given surface condition, images were collected at multiple locations  on the surface. All the STM data were processed using WSxM 5.0 software.42All the experiments were carried out in an ultrahigh vacuum system (base pressure approximately 1 × 1043–45 with Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional and in the generalized gradient approximation (GGA) formulation.46 We treated the electron-ion core interactions using the projector-augmented wave (PAW) pseudopotentials45,47 available in the VASP database. We constructed a four atomic layer thick p (7 × 7) Cu slab in Materials Studio48 by cleaving along the (111) plane. A vacuum of 20 Å thickness was applied on the slab along the z direction to prevent interactions of the slab with its upper/lower periodic images. The bottom layer was kept fixed and the remaining three layers were allowed to relax. Conjugate gradient algorithm with a Gaussian smearing width of 0.05 eV was used for all relaxations. Convergence tests were carried out, and a 1 × 1 × 1 k-point mesh with a plane wave energy cutoff of 400 eV was selected for the sampling of the Brillouin zone. The graphene fragments used in this study consist of three neighboring hexagonal rings. Graphene fragments were initially taken from Materials Studio structures database and then relaxed. Relaxed structures were then used on the Cu surface. Ab initio molecular dynamics (AIMD) were performed using VASP with the foregoing computational details. AIMD simulations were carried out in the NVT ensemble with a 1 fs time step and at two temperatures of 900 K and 1200 K.We performed our density functional theory (DFT) calculations using the Vienna Ab initio Simulation Package49–54 Gao et al. showed that epitaxial growth of graphene on Cu (111) by thermal decomposition of ethylene (C2H4) at 1000 °C results in formation of single-layer graphene platelets and sheets.33 Similarly, to produce large continuous graphene islands on Cu (111) surface, we undertook a controlled thermal cycling approach using the organic precursor, (C2H4). Successful preparation of large continuous graphene film over Cu (111) surface was confirmed by STM as shown in I/dV) image) were captured after the 7th cycle of thermal annealing. As shown in these two images, graphene islands and C atoms are both observed in one single image before final controlled annealing. Note that graphene islands look smoother and darker in differential conductance images. However, as shown in I/dV) image), after final cycle of thermal dissociation of C2H4 (8th cycle), complete graphene coverage over Cu (111) was observed. The domain boundaries are visible in these STM images. Note that the entire differential conductance image has a uniform color, which indicates that either all the terraces are Cu (111) or graphene/Cu (111) and 49 As shown in One promising approach to prepare large graphene sheets with low defects on metal substrates is by thermal dissociation of an organic precursor on the metal surface.6 rings and graphene islands on different adsorption sites has been studied elsewhere using DFT.4,55 Compared to these earlier studies, the cell used in this work is larger to accommodate end effects, and a GGA functional used (PBE) which is more accurate than the local density approximation (LDA). Using DFT optimizations, we allowed a C6 ring to relax onto the Cu (111) surface. We tested three main possibilities; (a) the ring surrounds a top Cu atom and the C atoms of the ring occupy fcc and hcp hollow sites (fcc–hcp), (b) the ring surrounds an hcp site and the C atoms occupy fcc and top sites (fcc-top), and (c) the ring surrounds an fcc site and the C atoms occupy hcp and top sites (hcp-top), alternately. Results, illustrated in Fig. S1 of ESI,Next we focused on a first-principles analysis of the graphene growth mechanisms. The adsorption of C13C atoms constituting 3 rings, to relax on the Cu surface. We studied 7 different orientations of the fragment with respect to the Cu lattice. These orientations were from 0° to 60° with 10° increments. Results are illustrated in Fig. S5 and S6 of ESI.38,56,57 Here, our focus was to determine the most favorable orientations of a graphene fragment rather than a graphene sheet on the Cu surface. This represents the initial nucleation stages observed experimentally on the Cu (111) terraces as discussed in relation to In addition, we also allowed a pre-relaxed graphene fragment, composed of 33 as well as our own. Prior to running AIMD simulations, the fragment was relaxed onto the Cu surface with an initial misalignment of 24° with respect to the Cu (111) lattice as shown in In the experimental part of this work, the technique of low and high temperature cycles was applied to grow the graphene sheet. Reportedly, graphene coverage can be controlled by the number of thermal cycles. Here we emulated several aspects of this process by using AIMD simulations to understand the effect of these cycles on the stability of the graphene fragments with respect to the underlying substrate. First, we studied the motion and rotation of an isolated fragment at two temperatures of 900 K and 1200 K. The selection of temperatures was largely dictated by other experimental studiesTo understand the effect that neighboring graphene fragments may have on a single fragment, we added a second fragment to the vicinity of the isolated fragment of the previous section. We note that the orientation of the second fragment with the first fragment was not set arbitrarily. We tried four different orientations of 0°, 30°, 60° and 90° between the two fragments. The most energetically favorable was the 60° orientation. This structure resulted in 24° misalignment of both fragments with the Cu (111) lattice and we started the AIMD simulations with this initial structure. †To study the effect of proximity on additional graphene islands in the vicinity of the first one, we placed the second graphene fragment of the previous section, closer (by 0.2 nm) to the initial fragment and relaxed the structure before running AIMD simulations. Results are shown in 58–60 Fe61 and Ni61,62 surface atoms in graphene growth was clearly observed in this part of the work. Both fragments were able to bond to two surface Cu atoms situated between the two fragments and by doing so, raise those atoms from the surface  surface when only small graphene islands have been formed. Hereafter, the islands may align with respect to one another and form a uniform graphene sheet or each may grow about their own specific alignment with the Cu lattice and produce various domains. We closely examined the effect that temperature may have in choosing either of these paths. We found that higher temperatures generally lead to the alignment of an island on the Cu surface. An isolated graphene pallet at high temperatures (above 900 K) is able to correct an initial misalignment and align itself perfectly with the Cu surface. This is attributed to the higher mobility of the Cu catalyst surface layer which allows graphene to rotate freely. As growth proceeds at lower temperatures and the number of graphene fragments increases, metal-bridging of surface Cu atoms which was observed unifies graphene islands. Therefore, increased growth rate at lower temperature combined with increased mobility at higher temperatures lead to production of large high quality graphene films with the perfect alignment of graphene islands with Cu lattice.There are no conflicts to declare.RA-008-C8RA05478A-s001


The Dark Triad has been found to be associated with malevolent creativity (MC) in terms of trait level, and its underlying mechanism remains unclear. Based on the cognitive–affective processing system theory and the existing studies, the current study aimed to explore the internal mechanism between the Dark Triad and MC behavioral tendencies/performance. The results revealed that the Dark Triad is positively related to MC behavioral tendencies through trait aggression and general creativity behavioral tendencies. Regarding MC performance, the Dark Triad is positively related to the originality of malevolent ideas through MC behavioral tendencies, but this effect is only significant at low-to-medium levels of moral identity. In line with moral identity theory, a higher moral identity may prevent individuals from acting immorally due to their desire to maintain their moral image, which may further suppress malevolent idea generation. Therefore, cultivating moral identity may be an effective approach to weaken the Dark Triad–MC performance association. Creativity is the ability to produce novel and useful work . TraditiGiven that creativity is, by nature, unexpected and rule-violating, the products of MC can be unpredictable and extremely dangerous . Thus, tThe cognitive–affective processing system (CAPS) has proposed several types of mediating units  that are activated by situational stimuli and further determine behaviors . In addiAccording to the CAPS, the mediating units interact and produce different behavioral responses . IndividThe current study aimed to answer the following question: How is the Dark Triad related to MC at the trait and behavior levels? Based on the above-mentioned studies, we hypothesized that (H1) behavioral tendencies of general creativity and aggression are significant mediators between the Dark Triad and MC behavioral tendencies and that (H2) MC behavioral tendencies mediate the relationship between the Dark Triad and MC performance , while moral identity moderates the MC behavioral tendencies–performance path.A total of 217 Chinese college participants  were recruited in the study. The recruiting poster was sent to the open college WeChat group, and anyone interested in the experiment could sign up through a QR code. Three participants were removed due to incomplete data. None of participants had a history of mental or neurological illness. The prior power analysis revealed that the sufficient sample size was 166 to obtain reliable results . It was used to measure MC performance by requiring participants to solve open-ended realistic problems in creative and malevolent ways . MCT conThe MCBS was used to measure malevolent creative behavioral tendencies , MCT, RIBS, BPAQ, DD12, and MIM .Before performing the MCT, participants were explicitly informed that all situations were fictitious in this experiment, and that malevolent ideas generated in this experiment were not related to their personality or level of morality. After completing the experiment, participants were asked whether they were all right (none of them claimed to feel unwell). Besides this, participants were also informed that psychological consultation was available and free for them if they needed it.r = .30, p < .001), aggression , and Dark Triad ; MCT harmfulness was positively correlated with MC behavioral tendencies  and creativity behavioral tendencies . Moreover, the correlation coefficient between the Dark Triad and MC behavioral tendencies was significantly higher than that between the Dark Triad and creativity behavioral tendencies  and other variables see . The resZ scores. Hierarchical regression analysis using gender , age, and other scale scores as independent variables was performed on MCT originality. The results of Step 3 revealed that MC behavioral tendencies  positively predicted MCT originality , age, and other scale scores as independent variables was performed on MCT harmfulness. The results of Step 3 revealed that none of these variables significantly predicted MCT harmfulness after controlling for age and gender see . The varb = .57, t = 10.24, p < .001; b = .40, t = 7.28, p < .001; b = .10; 95% confidence interval, 95%CI = ) and creative behavioral tendencies  significantly mediated the relation between the Dark Triad and MC behavioral tendencies. The VIF ranged from 1.08 to 1.26, which meant that multicollinearity did not seriously affect the result.Parallel multiple mediation analysis using the Dark Triad as an independent variable and BPAQ and RIBS as mediators was performed on MC behavioral tendencies see . PROCESSb = .16, t = 2.30, p = .022; b = −.03, t = −.41, p = .684; b = −.09; 95%CI = ; b = −.16; 95%CI = ). Specifically, MC behavioral tendencies significantly mediated the relation between the Dark Triad and MCT originality when moral identity was one SD lower than the mean  or equal to the mean ; the mediation effect of MC behavioral tendencies was insignificant when moral identity was one SD higher than the mean . The variance inflation factors (VIFs) ranged from 1.07 to 1.58, which meant that multicollinearity did not seriously affect these results.A moderated mediation model using the Dark Triad as an independent variable, MC behavioral tendencies as a mediator, moral identity  as a moderator, and MCT originality as a dependent variable was established See . Model 1The current study investigated the internal mechanism between the Dark Triad and MC . We observed that MC behavioral tendencies were positively correlated with the Dark Triad, aggression, and general creative behavioral tendencies. Moreover, the correlation coefficient between the Dark Triad and MC behavioral tendencies was higher than that between the Dark Triad and general creative behavioral tendencies. The results further revealed that the Dark Triad was related to MC behavioral tendencies through both aggression and general creative behavioral tendencies. Regarding MC performance, only MC behavioral tendencies positively predicted MCT originality after controlling for age and gender. Mediation analyses revealed that MC behavioral tendencies significantly mediated the relationship between the Dark Triad and MCT originality; the mediation effect of MC behavioral tendencies was only significant in low-to-medium levels of moral identity.The results showed that the Dark Triad was significantly correlated with general creativity and MC behavioral tendencies, which was consistent with the previous findings . Both thParallel multiple mediation analysis found that the relationship between the Dark Triad and MC behavioral tendencies was mediated by both aggression and general creative behavioral tendencies. This result partly supports our hypothesis . Researchers have demonstrated that individuals with higher aggression tend to generate more harmful ideas in general creativity tasks . A higheAt the behavioral level, MC behavioral tendencies positively predicted MCT originality (after the effects of age and gender were controlled for) and fully mediated the relationship between the Dark Triad and MCT originality. In addition, moral identity significantly moderated the path of MC behavioral tendencies–MCT originality in the mediation model. This supports our hypothesis . The Dark Triad refers to self-centeredness, manipulation, and callousness . These ‘In summary, the findings of the current study support CAPS and moral identity theory. Individuals with higher levels of Dark Triad personality traits tend to have higher aggression and general creativity behavioral tendencies, which then further cultivate their MC behavioral tendencies. At the behavioral level, MC behavioral tendencies may be closer to the originality than the harmfulness of malevolent ideation. The Dark Triad promotes MCT originality by fostering MC behavioral tendencies, but this mediation effect is only significant with low-to-medium moral identity. Based on the above-mentioned results, cultivating moral identity may be an effective way to prevent MC performance. Beyond the laboratory, MC performance in natural settings should be further investigated in the future. However, several limitations should be mentioned: (1) almost 76% of participants were female, so future studies should include more male participants; (2) only explicit aggression was explored, but implicit aggression could also be an effective source of malevolent creation; and (3) in addition to moral identity, moral reasoning and moral emotions should be further investigated in future studies.


Graphene doped by alkali atoms (AC Studying acoustic plasmons (APs) in single-layer ,2,3,4,5,As alkali atoms are added to graphene deposited on various substrates, they intercalate between the graphene layer and the substrate and metalize, i.e., they arrange in a two-dimensional (2D) crystal lattice, which supports a partially filled parabolic band ,19,20,21l doping ,23,24,25l doping ,34,35,36l doping ,38,39,40x) and the electrostatic doping. In other words, it is substantially unstable, and the aim of this research is to explore the mechanism of the (in)stability of the AP in the ACIn this paper, we focus on the AP, firstly because of its linear dispersion, but also because of the still rather unclear mechanism of its occurrence in the ACtime ago ,42,43. Itime ago . HoweverIn order to do that, we investigate two model systems of doped graphene, KCWe study electronic excitations in the ACapproach  and a reximation ,45. The The paper is organized as follows. In In this section, we derive the spectral function of the electronic excitations in the self-standing KCsumption  that thez direction is perpendicular to the crystal plane, the graphene layer occupies the We shall briefly describe the method of calculation of the surface electronic excitation spectra at the arbitrary position crystals ,48,49,50T. The matrix elements (or the charge vertices) areWe start from the 3D Fourier transform of the noninteracting (free) electron response functionz and z and L. We now need to determine the screened response function The Fourier expansion of the free electron response function in the Since the integrations in  are perfxpansion , and a sEquation , it agaiThe solution of Equation  has the z and After solving Equation , the nonF areThe propagator of the induced dynamically screened Coulomb interaction can be calculated from the response function  as 50]50](12)xpansion  and Equaxpansion , the intThe spectral function, which defines the intensity of the energy loss by an external perturbation to the excitation of the Up to this point, we derived the expressions for the self-standing q2D systems, but including a dielectric substrate polarization is now straightforward. It is obtained simply by replacing the bare Coulomb interaction  with theThis also means that the matrix  used in In the long-wavelength or optical limit σμinThe interband optical conductivity is determined from the optical limit of the nonlocal interband conductivityThe nonlocal interband conductivity is (24)σμinWe assume that the dielectric media is vacuum ϵFor the doped graphene, we follow the method proposed by Gjerding et al. , and wriin Refs. ,55, whic in Ref. , describG layers . We use We note that the relevant parameters for the KCgraphene , and by perature  as 4πEFgThe KC package . The cor package ,60. For nctional . The grok K-mesh  and the (PZ) LDA . The grog=2.45 Å , while fz) direction, the crystal local field effects are taken into account only in the z direction and neglected in the The ACunctions  and condunctions –25) are are8 resuctivity –(25) is k-point mesh and the band summations The ground state electronic density of the bulk Alfunction  of the Aalue 3.4 . However energy) . HoweverTo demonstrate that these effects are not driven by the dielectric substrate, in z direction), where the interband screening will be modified by changing the number of valence bands participating in the interband screening.To investigate this mechanism, we take advantage of the reduced model which clearly distinguishes between the different interband contributions to the dynamical response in the two systems. As discussed in n which denotes the number of omitted bands. For example, To explore how the screening coming from the interband excitations beyond the Fermi energy influences the AP, we omit one or more unoccupied bands from the calculation, to determine exactly how each band influences the excitation spectra. As we can see from the band structures shown in n. It is important to point out that we also attempted to keep the lowest unoccupied band in the calculation while omitting any number of the other unoccupied bands, above that one, and that did not lead to the occurrence of the AP in the CsCAnother interesting point is that the difference in the intensities of the We analyzed the origin of AP instability in graphene doped by alkali metals on two prototype systems, KC


Soluble programmed cell death-ligand 1 (sPD-L1) has been well documented to activate immunosuppression and is considered an essential predictor of negative clinical outcomes for several malignances and inflammatory conditions. However, the clinical significance of sPD-L1 in the peripheral blood of patients with coronary artery disease (CAD) remains unclear. The aim of this study was to assess the correlations of sPD-L1 with clinical features in CAD patients and evaluate the diagnostic value of this protein in CAD.A total of 111 CAD patients and 97 healthy volunteers who served as healthy controls (HCs) were consecutively enrolled. Plasma levels of sPD-L1 were measured with an amplified enzyme-linked immunosorbent assay (ELISA), and hs-CRP was measured with a C-reactive protein assay kit. The levels of other inflammatory cytokines were assessed in 88 CAD patients and 47 HCs by a multiparameter immunoluminescence flow cytometry detection technique. A logistic regression model was used to assess the independent association of sPD-L1 with acute coronary syndrome (ACS). The correlation between sPD-L1 and inflammatory cytokines in ACS was also assessed.p < 0.001), BMI, hypertension, diabetes, dyslipidemia, previous MI, and the levels of HDL-C, LDL-C and hs-CRP were significantly associated with ACS. sPD-L1  was found to be independently and significantly associated with ACS in the subsequent multivariable logistic regression analysis. Additionally, elevated plasma sPD-L1 levels were associated with increased interleukin-6 and interleukin-8 levels in ACS patients. Receiver operating characteristic (ROC) analysis showed that the AUC of sPD-L1 for diagnosing ACS was 0.778, with a sensitivity of 73.9% and a specificity of 73.4%, which was comparable with that of the inflammatory biomarker hs-CRP.Plasma levels of sPD-L1 were significantly increased in CAD patients, especially those with ACS. Univariate logistic regression analysis revealed that sPD-L1 (OR: 3.382, 95% CI: 2.249–5.084, The plasma sPD-L1 level reflects the severity of CAD, is associated with inflammatory responses and is a potential new biomarker for the diagnosis of ACS. Coronary artery disease (CAD), a cardiovascular disease, is the leading cause of death in both developed and developing countries . CAD is Programmed death 1 (PD-1) is a key immunosuppressive molecule. PD-1 has two natural ligands, and its primary ligand, PD-L1 , is expressed on the surface of activated T cells and macrophage-lineage cells, as well as some non-hematologic cells, such as those in the placenta and heart , 12. TumAs a transmembrane protein, PD-L1 is mainly expressed on the cell surface. In addition, several soluble forms of PD-L1 (sPD-L1) have been described, including cleaved, alternatively spliced and exosomal sPD-L1, which are released from cells into body fluids. Similar to membrane-bound PD-L1, sPD-L1 is currently thought to contribute to systemic immunosuppression –17. SeveWe found that plasma levels of sPDL-1 were definitely increased in CAD, particularly in ACS patients. The production of sPD-L1 tends to reflect the severity of CAD disease and is associated with inflammatory responses in atherosclerosis. These preliminary results may provide clues for developing new biomarkers for CAD patients in clinical practice.One hundred thirty-three CAD patients who were screened for coronary disease by coronary angiography were consecutively admitted to the Beijing Chest Hospital Heart Center and Emergency Department at the Affiliated Hospital of Jining Medical University between February 2021 and November 2021. The exclusion criteria included malignant diseases, current hemodialysis, active systemic inflammatory diseases , and peripheral arterial occlusive diseases causing pain at rest during the same study period. In addition, 97 of 127 healthy volunteers were included as the control (HC) group. Ultimately, 111 patients and 97 HCs were included in this study. The studies involving human participants were reviewed and approved by the Ethics Committee of Beijing Chest Hospital, Capital Medical University (IRB number: 2021-KY-35) and the Affiliated Hospital of Jining Medical University (2022C047) and were performed according to the Declaration of Helsinki Principles.Acute myocardial infarction (AMI) was defined as an increase in plasma levels of cardiac troponin above the 99th percentile of the upper limit of the normal range together with evidence of myocardial ischemia and at least one of the following findings: electrocardiographic changes , imaging evidence of new viable myocardial loss, or a new abnormality in regional wall motion . UnstablPeripheral blood samples of patients were obtained in the catheter-laboratory room soon after sheath insertion and before the administration of heparin. Clinical parameters  were part of the standard workup at the Laboratory Diagnosis Center. In addition, to measure the levels of sPD-L1, high-sensitivity troponin I (hs-TnI), hs-CRP and inflammatory cytokines under the same conditions, all blood samples, including those from the 68 AMI, 24 UA, and 19 CCS patients and the 97 HCs, were centrifuged at 2500 rpm for 10 min at room temperature, and the plasma was collected and kept frozen at −80°C until measurement. Repeated cycles of freezing and thawing of the samples were avoided.R2 = 0.9998) was established.Monoclonal anti-human PD-L1 mAbs were generated by immunizing BALB/c mice with PD-L1-Fc fusion proteins containing the extracellular domain (Met 1-Thr 239) of human PD-L1  with the C-terminal fused Fc region of human IgG1 that was expressed in HEK293 Cells. Using immune spleen cells and the mouse myeloma SP2/0 cell line as a fusion partner, mouse hybridomas were generated and selected by the same PD-L1-Fc fusion protein and PD-L1-His (Met 1-Thr 239) fusion protein. More than 40 positive wells were screened, and two mAbs, 11E3 and 2F1, were finally identified. The two antibodies were effectively used in ELISA, flow cytometry and western blot, and 11E3 can also be used in immunohistochemical detection. In addition, 11E3 is the blocking antibody of PD-1/PD-L1 binding, while 2F1 is the non-blocking antibody. Therefore, the two antibodies were successfully paired for sandwich ELISA. 11E3 was used as the capture antibody, and biotin-labeled 2F1 was used as the detection antibody, so an amplification test with an expected sensitivity of 5 pg/ml . Plasma levels of sPD-L1 were measured using ELISA Costar ELISA plates coated with anti-human PD-L1 mAb  overnight at 4°C. The plates were then blocked with 5% skim milk  for 2 h 37°C. Plasma samples that were obtained from patients and healthy controls and diluted 25-fold were added to each well of the antibody-coated plates and incubated overnight at 4°C. The captured sPD-L1 was detected using 2 μg/ml biotinylated anti-PD-L1 mAb (Bio2F1) followed by incubation with streptavidin-HRP  for 0.5 h at room temperature (RT). The samples were developed using the TMB Substrate Reagent Set , and then Stop Solution  was added. The optical density (OD) was evaluated at 450 nm with a MULTISKAN GO instrument . The plates were washed three times with 1 × PBS containing 0.5‰ Tween-20 following every step.According to the Centers for Disease Control and Prevention and the American Heart Association, it is recommended that hs-CRP be monitored to assess cardiovascular risk and tested as a routine laboratory parameter . Hs-CRP To further evaluate the systemic inflammatory response in patients with ACS, we randomly selected 88 of the 111 CAD patients and 47 of the 97 HCs for the measurement of 14 inflammatory cytokines. These selected plasma cytokines were measured by an immunofluorescence assay that can recognize 14 cytokines   according to the manufacturer’s instructions. The assay is based on the principle of combining a liquid-phase chip and double antibody sandwich and consists of 14 kinds of microspheres with different fluorescence intensities coated with specific antibodies for each cytokine (capture microspheres), which can capture the corresponding cytokines in plasma samples. When the corresponding cytokine is specifically bound, a biotin-labeled detection antibody is added to form an immune complex of capture microspheres and cytokine-detection antibody; then, PE-labeled streptavidin (SA-PE) is added, and the corresponding fluorescence on the microspheres is detected using multiparameter immunoluminescence flow cytometry . Thus, the concentration of the individual cytokines in the sample to be measured is obtained from the fluorescence intensity of the immune complex microspheres. The relative deviation of the detection results is within ±15%, and the lower limit of detection (LOD) of this kit is 2.3 pg/mL.2 or Fisher’s exact test was used to compare differences between categorical variables. The Bonferroni method was used to adjust for comparisons among three or more groups. The Mann–Whitney test was used for two-group comparisons. The Kruskal–Wallis test was used for non-normal distributions to compare three or more groups. Clinical parameters that were significantly associated with ACS in univariate logistic regression analysis were evaluated using multivariable logistic regression analysis. The odds ratios (ORs) and 95% confidence intervals (CIs) were presented. Z scores were also used to make ORs comparable (per standard deviation) among the biomarker covariates in logistic regression analyses. To assess model calibration, the Hosmer–Lemeshow statistic for multivariable logistic regression was applied. To compare the association, Spearman’s rank correlation coefficient was calculated between each data set. Receiver operating characteristic (ROC) analysis was applied to evaluate the accuracy and diagnostic ability of sPD-L1. The area under the curve (AUC) of the ROC curve was calculated, along with sensitivity and specificity values. A p-value < 0.05 was considered indicative of statistical significance. Statistical analyses were performed using SPSS software v.20.0 . The statistical software GraphPad Prism 8.0  was used for all statistical tests and graph creation.Continuous variables were expressed as the mean ± standard deviation (SD) for normally distributed variables according to the Shapiro-Wilk test, and the median value with interquartile range (IQR) was used for a non-normal distribution. Categorical variables were presented as frequencies and percentages. The χn = 2), current hemodialysis (n = 1), active systemic inflammatory diseases (autoimmune diseases and rheumatoid diseases requiring immunosuppressive therapies) (n = 7), age greater than 75 years (n = 11), and missing information (n = 1). One hundred twenty-seven healthy volunteers were included as the healthy control (HC) group. Finally, 111 patients with CAD  and 97 HCs were enrolled in this study. The study flow chart is presented in A total of 133 patients with CAD who were screened for coronary disease by coronary angiography (coronary stenosis of >50% of the vessel diameter detected) and/or a history of MI, PCI, or CABG were consecutively admitted to the Heart Center of Beijing Chest Hospital, Capital Medical University and the Affiliated Hospital of Jining Medical University between February 2021 and November 2021. Among them, 22 patients met the following exclusion criteria: active malignant diseases  vs. (129.11 ± 14.26) g/dL, p < 0.001], ejection fraction , hs-TnI , nitrate use , beta blocker use , ACEI or ARB use , and hs-CRP  , that was significantly associated with ACS. In addition, one laboratory index, hs-CRP , was significantly and independently associated with ACS. The Hosmer–Lemeshow goodness of fit chi-square result was 3.086 with a p value of 0.929. Relying on the same analysis method, this study found that sPD-L1 was also significantly associated with ACS by univariate logistic regression analyses . Moreover, the multivariate logistic regression analyses that included nine significant factors identified in the univariate analysis demonstrated that sPD-L1 was significantly and independently associated with ACS , which indicated that sPD-L1 could be a new laboratory biomarker that is independently associated with ACS  pg/ml, p < 0.001] (p < 0.001)  pg/ml, and in 111 CAD patients at the median level of 247.03 (191.86–296.34) pg/ml. In addition, we analyzed the ACS and CCS subgroups from the overall group of 111 CAD patients. The median levels of sPD-L1 were 256.72 (204.57–301.01) and 188.32 (160.67–216.82) pg/ml, respectively. Statistically, patients with CAD showed significantly higher levels of sPD-L1 than HCs  . Further< 0.001] . The sPD< 0.001) .p < 0.001], those with CCS , and the HCs  . In cont= 0.021] . These r= 0.021] . Additio= 0.337) . These rr = 0.282, p = 0.017); IL-8, ]  ] . In addi= 0.008) . These rp < 0.001), which showed a favorable diagnostic efficacy for ACS. In addition, hs-CRP, an inflammatory biomarker, had a cutoff value of 0.87 mg/L with a sensitivity of 79.3% and specificity of 72.1% in this study. The AUC was 0.769 . Hs-CRP is frequently considered to be a predictor of cardiovascular events. Therefore, we conclude that sPD-L1  which exhibited results similar to those of hs-CRP , can potentially serve as a novel biomarker of disease in discriminating ACS from CAD.In this study, sPD-L1 was shown to be an independent predictive marker associated with ACS. Finally, we evaluated its diagnostic accuracy for ACS patients. As indicated in –9 mol/L  and 6.96 × 10–9 mol/L , respectively . C-reactive protein is a definitive biomarker for inflammation and has been established in clinical practice as an independent risk factor for cardiovascular disease events  was 0.778. Furthermore, the optimum hs-CRP cutoff for the diagnosis of ACS was 0.87 mg/L, with a sensitivity of 79.3% and a specificity of 72.1%. The AUC was 0.769 ; the Affiliated Hospital of Jining Medical University (2022C047). The patients/participants provided their written informed consent to participate in this study.JZ and HZ contributed to the conception and design. SL, XWe, JgZ, CJ, LS, and XG contributed to the blood sampling collection and clinical data acquisition. SL, LY, XWa, ZY, BY, PW, and JW contributed to the experimental operation. JZ, HZ, and SL contributed to the analysis and interpretation of the data, writing, review, and/or revision of the manuscript. JZ contributed to the study supervision. All authors contributed to the article and approved the submitted version.