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The interaction of H, H2, and MgH2 with graphene is investigated using the density functional theory to explore the possibility of exploiting graphene or functionalized graphene as a hydrogen storage medium. The H atom is positioned at various distances from the graphene surface and the energetics are computed in detail. The extent of interaction of the s electron of H with graphene's pz electrons is well brought out. Similar investigations are carried out for H2, MgH2. In the case of H atom, a HC covalent bond is formed. This process turns out to be a prerequisite for proton transfer through graphene. Interactions of H2 and MgH2 with graphene are different from that of H. It leads to the conclusion that functionalized graphene will better substrate/candidate for applications like hydrogen storage. [ABSTRACT FROM AUTHOR]

We develop a new type of heterostructure nanocomposite made of reduced graphene oxide-boron carbon nitride nanosheets (rGOBCN) by B–C covalent bonds. The rGO-BCN nanocomposite delivers a large specific surface and excellent electrochemical properties, and is then constructed into flexible fabric-based high-performance supercapacitor electrodes based on the microfluidic electrospinning technology. [ABSTRACT FROM AUTHOR]

This paper presents a computational procedure for the determination of the dynamic behaviour of graphene with different types of defects. The lattice of graphene is modelled using the molecular structural mechanics (MSM) approach, where the C–C covalent bonds are replaced by equivalent beam elements. Cantilever and bridged boundary conditions are applied for the analysis. Four types of Stone–Wales (SW) defects such as S-W (555-8), S-W (555-888-3), S-W (555-77-8) and S-W (888-3), and two types of pinhole defects with 6 and 24 elements eliminated are examined on armchair, zigzag and chiral type of graphene sheet. The effect of the structural length of the sheet, chirality and defect type on the vibrational properties of graphene sheets is investigated. The computed results reveal that SW defects produce a high frequency to that of pristine graphene, whereas the effect of pinhole defects is significant as compared to SW defects. The computed results will be useful in nano-resonator-based sensor applications. [ABSTRACT FROM AUTHOR]

Large‐area graphene grown by chemical vapor deposition is functionalized by p‐aminophenyl groups via the diazonium‐route. Subsequently, carboxylic acid‐modified CdSXSe1‐X/ZnS dots (QDs) with maximum emission wavelengths of 540 nm and 630 nm are immobilized via amidation reaction to the amino‐functionalized graphene on the copper growth substrate forming stable covalent bonds in all functionalization steps. After immobilization of the QDs, the functional QD/graphene stack is available for transfer from the growth substrate onto any other substrate. In this study, the QD‐modified graphene is transferred to a Si wafer with surface oxide without losing the QD modification. The successful binding of the QDs onto the functionalized graphene is characterized by their vibrational signature using Raman backscattering and infrared‐spectroscopic ellipsometry and by their specific light emission as measured by photoluminescence (PL) spectroscopy. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this article is to prepare graphene/polyimide composite materials for use as bearing cage materials, improving the friction and wear performance of bearing cages. Design/methodology/approach: The oil absorption and discharge tests were conducted to evaluate the oil content properties of the materials, while the mechanical properties were analyzed through cross-sectional morphology examination. Investigation into the tribological behavior and wear mechanisms encompassed characterization and analysis of wear trace morphology in PPI-based materials. Consequently, the influence of varied graphene nanoplatelets (GN) concentrations on the oil content, mechanical and tribological properties of PPI-based materials was elucidated. Findings: The composites exhibit excellent oil-containing properties due to the increased porosity of PPI-GN composites. The robust formation of covalent bonds between GN and PPI amplifies the adhesive potency of the PPI-GN composites, thereby inducing a substantial enhancement in impact strength. Notably, the PPI-GN composites showed enhanced lubrication properties compared to PPI, which was particularly evident at a GN content of 0.5 Wt.%, as evidenced by the minimization of the average coefficient of friction and the width of the abrasion marks. Practical implications: This paper includes implications for elucidating the wear mechanism of the polyimide composites under frictional wear conditions and then to guide the optimization of oil content and tribological properties of polyimide bearing cage materials. Originality/value: In this paper, homogeneously dispersed PPI-GN composites were effectively synthesized by introducing GN into a polyimide matrix through in situ polymerization, and the lubrication mechanism of the PPI composites was compared with that of the PPI-GN composites to illustrate the composites' superiority. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0415 [ABSTRACT FROM AUTHOR]

The structural, electronic and Li-ion diffusion properties of LiFePO4 (010) surface modified by graphene have been investigated by first-principles calculation under the DFT+U framework. The calculated formation energy indicates that the LiFePO4 (010) surface modified with graphene is energetically favourable. It is found that strong C-Fe and C-O covalent bonds are formed at the modified interface, and the band gap of LiFePO4 modified with graphene is narrowed, indicating better electronic conductive properties. The energy barrier for the diffusion of Li-ion along the bchannel perpendicular to the (010) surface is calculated using the method of finding the transition state. The results show that the energy barrier of the modified system is reduced, indicating that the surface modification of LiFePO4 by graphene can improve the surface diffusion rate of Li-ions. [ABSTRACT FROM AUTHOR]

Binary transition metal sulfides have garnered widespread concentration result from their superior electrical conductivity and outstanding capacitance. However, their poor cycling stability hinders their applications in energy storage devices. The objective of this study is to devise and prepare graphene and NiCo2S4 composite (NiCo2S4@graphene) using a simple one-step hydrothermal modality. Graphene is used as a conductive substrate, and NiCo2S4 nanoparticles are formed in situ and homogeneously anchored on graphene nanosheets through C-S-C covalent bonds. For example, the NiCo2S4@graphene composite has a high specific capacitance of 918.0 C g−1 at a current density of 1 A g−1 and enhanced cycling stability (90.1% after 6000 cycles). In addition, the asymmetric supercapacitor was fabricated with NiCo2S4@graphene as the positive electrode and graphene (GR) as the negative electrode, and the device provided a maximum energy density of 49.8 Wh kg−1 at a power density of 845.3 Wh kg−1. Besides, the capacitance retention rate was as high as 92.0% after 1000 cycles. The superior electrochemical properties of the NiCo2S4@graphene material verified its huge potential for realistic applications. [ABSTRACT FROM AUTHOR]

Controllable synthesis of defect-free graphene is crucial for applications since the properties of graphene are highly sensitive to any deviations from the crystalline lattice. We focus here on the emerging use of liquid Cu catalysts, which have high potential for fast and efficient industrial-scale production of high-quality graphene. The interface between graphene and liquid Cu is studied using force field and ab initio molecular dynamics, revealing a complete or partial embedding of finite-sized flakes. By analyzing flakes of different sizes, we find that the size-dependence of the embedding can be rationalized based on the energy cost of embedding vs bending the graphene flake. The embedding itself is driven by the formation of covalent bonds between the under-coordinated edge C atoms and the liquid Cu surface, which is accompanied by a significant charge transfer. In contrast, the central flake atoms are located around or slightly above 3 Å from the liquid Cu surface and exhibit weak van der Waals–bonding and much lower charge transfer. The structural and electronic properties of the embedded state revealed in our work provide the atomic-scale information needed to develop effective models to explain the special growth observed in experiments where various interesting phenomena such as flake self-assembly and rotational alignment, high growth speeds, and low defect densities in the final graphene product have been observed. [ABSTRACT FROM AUTHOR]

Carbon atoms can connect with themselves and with other atoms (both electronegative and electropositive elements) in various ways. Thanks to these abilities, the diversity of carbon compounds is increasing day by day. This growth was even faster after the discovery of carbon nanoallotropes, i.e. carbon nanotubes, fullerenes, and graphene. At present, these carbon nanoallotropes are widely studied, and new hybrid structures have been synthesized based on these nanoallotropes. Hybrid structures formed by the covalent bond of fullerenes to the outside carbon nanotubes are called carbon nanobuds (CNBs). Development of synthesis methods, computational calculations, and the study of CNB properties was much faster than other hybrid structures. However, only fewer articles on CNBs have been published in recent years. CNBs show a synergistic effect and have the unique properties of the carbon nanoallotropes from which they formed. This review discusses CNBs and reports the recent research on CNBs, mostly after 2016. [ABSTRACT FROM AUTHOR]

State‐of‐the‐art carbon coatings are sought to protect high‐capacity silicon anodes, which suffer from low conductivity, large volume change and fast degradation. However, this approach falls short when handling physical–electrical disconnections between carbon shells and silicon microparticulate (SiMP) with drastic size variations. Here, a strategy of covalent coating is developed to establish a robust encapsulation structure. The obtained covalent SiC bonds enable an effectively dynamic connection between the electrochemically deforming SiMP and the sliding graphene layers, preventing the evolution of gaps between SiMP and the carbon shell and maintaining persistent electrical connections as well as mechanical toughness. As a result of high structure reversibility, the cycling stability of thick SiMP anodes is greatly improved, up to a high areal capacity of 5.6 mAh cm−2 and volumetric capacity of 2564 mAh cm−3. This interface bonding effect demonstrates the great potential for suppressing deformation involved degradation of high‐capacity materials through coating strategies. [ABSTRACT FROM AUTHOR]

Presented is a concentrated synopsis of facilities of empirical and virtual analytics that, once applied, have provided a fully new vision of sp2 amorphous carbons. This study proved that the solids are multilevel structures, started with the first-level basic structural units (BSUs) and accomplished as macroscopic agglomerates of globular structures, consisting, in its turn, of stacked BSUs. BSUs present necklaced graphene molecules, size, and shape of which are governed by the relevant graphene domains while chemical composition in addition to basic carbon is controlled with heteroatoms of the necklaces. This study shows that BSUs and stacks of BSUs determine the short-range order of the solids and are the main subject of the applied analytics. The synopsis consists of two parts related to empirical and virtual analytics. The former is composed of sections related to structural determination, total and atomic chemical content evaluation and elicitation of the covalent bond composition. The second presents new analytic approaches based on the Digital Twins concept and virtual vibrational spectrometry. The synopsis is configured as an atlas composed of generalized pictures accompanied with necessary explanations to be discussed in detail in the extended references. [ABSTRACT FROM AUTHOR]

Context: Nanosensors and actuators are frequently made of graphene. Any defect in the graphene's manufacturing has an impact on its sensing performance and on its dynamic behaviour. Using a molecular dynamics technique, the influence of pinhole defects and atomic defects on the performance parameters of single-layer graphene sheets (SLGSs) and double-layer graphene sheets (DLGSs) with various boundary conditions and lengths is explored. In contrast to the perfect nanostructure of a graphene sheet, defects are described as holes formed by atomic vacancies. As the number of defects increases, the simulation results show that the presence of defects has the greatest impact on the resonance frequency of SLGSs and DLGSs. The influence of pinhole defect (PD) and atomic vacancy defect (AVD) on armchair, zigzag, and chiral SLGSs and DLGSs was investigated in this article using molecular dynamics simulation. The influence of both types of defects is largest when it is adjacent to the fixed support for all three different types of graphene sheets, i.e. armchair, zigzag, and chiral. Methods: The structure of the graphene sheet has been created using ANSYS APDL software. In the structure of the graphene sheet, atomic and pinhole defects have been generated. SLG and DLG sheets are modelled using a space frame structure that is identical to a three-dimensional beam. Dynamic analysis of single-layer and double-layer graphene sheets performed with different lengths using the atomistic finite element method. The interlayer separation in the form of Van der Waals interaction is modelled using characteristic spring element (Combin14). The upper and lower sheets of DLGSs are described as elastic beams connected by a spring element. With atomic vacancy defect for the bridged boundary condition, the highest frequency of 2.86 × 108 Hz was found for zigzag DLG (20 0) and with same boundary condition for pinhole defect 2.79 × 108 Hz frequency achieved. In a single-layer graphene sheet with an atomic vacancy and cantilever boundary condition, the maximum efficiency was 4.13 × 103 Hz for SLG (20 0), while in a pinhole defect, it produced 2.73 × 107 Hz. Moreover, the elastic parameters of beam components are calculated using the mechanical properties of covalent bonds between carbon atoms in the hexagonal lattice. The model has been tested against previous research. The focus of this research is to develop a mechanism for determining how defects affect graphene frequency band in application as nano resonators. [ABSTRACT FROM AUTHOR]

Efforts to fabricate high-conducting and high-strength free-standing graphene/carbon nanotube (CNT) buckypaper through room-temperature functionalization have been frustrated by the defective surface of the graphene and CNTs. In this study, high-quality graphene sheets were prepared via an amino-assisted liquid phase exfoliation method and used to integrate with CNTs to form free-standing flexible graphene/CNTs buckypaper. After that, individual graphene and CNT of the graphene/CNTs buckypaper were linked via diazonium chemistry to generate covalent bonds. By tuning functionalization time, the functionalized graphene/CNTs buckypaper exhibits an electrical conductivity of 87,500 S/m and a Young's modulus of 22.3 GPa, which are 6 and 10 times higher, respectively, than unfunctionalized graphene/CNTs buckypaper. Density functional theory calculations demonstrate that charge transfer rate (K et) of the aryl linker bonded moiety configuration via covalent functionalization is an order faster than without the aryl linker bonded moiety configuration. Unprecedently, the capacitance of the functionalized graphene/CNTs buckypaper is 359.6 mF/cm3 at a scan rate of 1 mV/s with no capacitance change after 10,000 cycles of testing. This work sheds the light of the value of molecular engineering in the design of novel composite for flexible electronics, energy storage and provides important insights into the understanding of basic principles of covalent functionalization of graphene/CNTs. The functionalized graphene/CNTs buckypaper were crosslinked to form covalent bonds between individual material via diazonium chemistry reaction and it achieved an electrical conductivity of 875 S/cm and Young's modulus of 22.3 GPa, which are 6 and 10 times higher than unfunctionalized graphene/CNTs buckypaper. Besides, charge transfer rate (K et) of the functionalized graphene/CNTs shows ten times faster than unfunctionalized moiety configuration. [Display omitted] [ABSTRACT FROM AUTHOR]

Based on the first-principles method, TiAlSiN/WC-Co interface models with graphene doped into the matrix, coating, and the coating/matrix are constructed. The interface adhesion work is calculated and modeled to study the interface bonding properties from the atomic microscopic point of view. The results show that the interface bonding properties of TiAlSiN/WC-Co can be improved when the matrix is doped with the main surface of intrinsic graphene, and the interface bonding property of TiAlSiNN/WC-Co can be improved when the coating and coating/matrix are doped separately with the main surface of intrinsic graphene or single vacancy defective graphene. Furthermore, the model electronic structures are analyzed. The results show that there exist strong Si/Co and N/Co covalent bonds in the interfaces when the matrix is doped with the main surface of intrinsic graphene, which causes the adhesion work of TiAlSiN/WC/msGR/Co to be greater than that of TiAlSiN/WC-Co. Additionally, when the graphene is doped into the coating, in the interface of TiAlSiN/msGR/TiAlSiNN/WC-Co, there exist strong N/Co covalent bonds that increase the interface adhesion work. Additionally, more charge transfer and orbital hybridization exist in the coating/matrix interface doped with the main surface of intrinsic graphene or single vacancy defective graphene, which explains the essential mechanism that the adhesion work of TiAlSiNN/msGR/WC-Co is greater than that of TiAlSiNN/WC-Co, and the adhesion work of TiAlSiNN/svGR/WC-Co is greater than that of TiAlSiNN/WC-Co. [ABSTRACT FROM AUTHOR]

The fluorination of self-standing graphene oxide (GO) films under mild conditions at 70 °C for 1h using a mixture of elemental fluorine and nitrogen gases (0.35 F 2 /0.65 N 2 v/v) results in transparent, highly fluorinated (F/C = 1 as seen by XPS) graphene oxide (FGO) films which maintain initial densely packed structure and mechanical strength. Most of the oxygen atoms in the GO film were replaced by fluorine after fluorination, and two types of carbon-fluorine bonds coexist, i.e. primarily weakened C⋯F bonds and also pure covalent C–F bonds as evidenced by FTIR, XPS, NMR, and cyclic voltammetry when FGO is used as electrode in Li/electrolyte (PC:EC:3DMC/LiTFSI 1 M)/FGO cell similar to a lithium battery. To further understand the fluorination mechanism and to distinguish the reaction steps, xenon difluoride XeF 2 was used as fluorinating agent for GO and in situ EPR and FTIR analyses suggest hydroxyl groups as preferential reactive sites. These self-standing transparent FGO films exhibit unusual electrochemical properties in lithium battery and can be used as hydrophobic lubricant membranes because of the low and stable coefficient of friction evidenced in the present work. [Display omitted] [ABSTRACT FROM AUTHOR]

Vertical graphene sheets (VGs), covalently bonded to diamond substrate, can exhibit ultra-high mechanical robustness against scratching, friction, and compression. In this study, AFM tests with a diamond probe were preformed to investigate the interfacial mechanical properties of VGs film fabricated on diamond substrate. The unique bonding structure between VGs and diamond, featured with an ultra-strong C–C covalent bonds, effectively inhibited VGs being uprooted from diamond substrate even under a contact pressure as high as 53.7 GPa. Despite the inevitable breakage of graphene sheets under a contact pressure exceeds 25 GPa, the fractured graphene sheets residuals, which retain their covalent bonds to diamond substrate, could still act as a mechanically robust VGs film. Furthermore, in a long-duration AFM friction test, the VGs exhibited a highly stabilized coefficient of friction around 0.03 and a nearly ignorable specific wear rate as low as 2.0 × 10−4 mm3/Nm. Due to the relative slipping between adjacent graphene sheets was inhibited by the interfacial covalent C–C bonds between VGs and diamond substrate, the compressed VGs film transformed into a scale-like structure that consist of compactly stacked graphene sheets with a certain concentration of sp 3 bonds (up to 8%) forming inside. This structure, characterized with extremely high elastic modulus and compressive strength, substantially attributed to the ultrahigh stability and sustainability exhibited by VGs upon friction and compression. The findings presented here is expected to boost utilizations of VGs and diamond combined in electronics, optical, mechanical, and tribological fields. [Display omitted] [ABSTRACT FROM AUTHOR]

The dopants of sulfur, nitrogen, or both, serving as the active sites, into the graphitic framework of graphene is an efficient strategy to improve the electrochemical performance of electrochemical membrane filtration. However, the covalent bonds between the doped atoms and the substrate that form different functional groups have a significant role in the specific activity for pollutant degradation. Herein, we found that the singly doped heteroatom graphene (NG and SG) achieved superior removal efficiency of pollutants as compared with that of the double doped heteroatom graphene (SNG). Mechanism studies showed that the doped N of NG presented as graphitic N and substantially increased electron transfer, whereas the doped S of SG posed as -C-SOx-C- provided more adsorption sites to improve electrochemical performance. However, in the case of SNG, the co-doped S and N cannot form the efficient graphitic N and -C-SOx-C- for electrochemical degradation, resulting in a low degradation efficiency. Through the fundamental insights into the bonding of the doped heteroatom on graphene, this work furnishes further directives for the design of desirable heteroatom graphene for membrane filtration. [ABSTRACT FROM AUTHOR]

The research progress of graphene in covalent and non-covalent modification and its application in composites were reviewed. Covalent bond modification mainly involves substitution reaction, condensation reaction and addition reaction; non-covalent modification mainly includes self-assembly, van der Waals force and hydrogen bond. At the same time, the development ideas of graphene modification technology in the future were summarized and analyzed. In the future, the research in this field will focus more on the environmental protection and economy of graphene modification. The development of new graphene modification processes and technologies with low environmental pollution and low cost will become the main goal in the future. [ABSTRACT FROM AUTHOR]

[Display omitted] • A graphene-based field-effect transistor aptasensor is development for prostate-specific antigen detection. • The novel approach used 1-pyrenebutyric acid N-hydroxysuccinimide ester to functionalize graphene. • The biosensor has detected PSA concentrations from 100 fM to 100 nM with a low detection limit of 3.5 pM. • The biosensor exhibits high specificity and reproducibility for accurate PSA quantification in human serum samples. The development of a graphene-based field-effect transistor (GFET) aptasensor for prostate-specific antigen (PSA) detection. We present the novel use of 1-pyrenebutyric acid N-hydroxysuccinimide ester (PBASE) to functionalize the graphene surface, enabling covalent bonding of amine-functionalized PSA-binding aptamers. Under optimized conditions, the shift of the GFET aptasensor's Dirac point voltage exhibited a systematic variation with PSA concentrations. The sensor demonstrated a relatively wide linear dynamic range spanning from 100 fM to 100 nM, with a detection limit of 3.5 pM. Importantly, it displayed satisfactory specificity against potential interfering proteins and demonstrated good reproducibility and stability. Furthermore, we successfully applied the proposed method for the quantification of PSA in human serum samples, indicating its potential for bioanalysis and clinical diagnostics. The GFET aptasensor's potential in medical diagnostics and personalized healthcare, positioning it as a promising tool for rapid and accurate biomarker detection. [ABSTRACT FROM AUTHOR]

Summary: Fuel cells have been developed efficiently in recent years as a secure and high‐energy conversion technology. The innovation in electrocatalysis focuses on initiatives to minimize or replace Pt electrodes used. As an alternative, organic aerogel materials are normally used as electrodes in low temperature fuel cells due to their high electronic conducting and electrocatalytic characteristics. These are usually characterized by fundamental functional elements of strong covalent C‐C bonds from organic precursors. This review will mainly focus on organic aerogel nanomaterials related to carbon aerogels, carbon nanotube aerogels, and graphene aerogels as electrocatalytic supports by surface modification or structural features in catalysis. In contrast, organic aerogel materials prove to be durable, economical, and active electrocatalysts that can provide outstanding electrocatalytic efficiency in low temperature fuel cell applications. Last, this paper recaps the challenges faced in current fuel cell applications and the use of organic aerogel materials to address these challenges. [ABSTRACT FROM AUTHOR]

Using quantum mechanical approaches, the electronic and electrophysical properties of T-contact connections based on thin chiral single-walled carbon nanotubes (SWCNTs) and graphene zigzag nanoribbons are studied from the standpoint of their application as field-emission blade-type nanoemitters with an atomic thickness of the emitting blade. The fact of a sharp decrease in the contact electrical resistance by 87% for the investigated three-pole contact (T-contact) from the side of two contacts, which are semi-infinite SWCNTs, is established. Resistance of a graphene zigzag nanoribbon connected perpendicular to the contacts from SWCNTs as part of a three-pole is comparable to the resistance of the nanoribbon itself and is ~3.3 kΩ. It is shown that the covalent bonds of graphene ribbons with nanotubes predetermine a high tensile strength in strong electric fields, which ensures the integrity of the atomic structure even in electric fields of ~1.5 × 108 V/nm. It was revealed that the mechanical force of the electric field, which is from 23 to 36 nN, causes periodic deformations of the atomic frame with a frequency of ~1.25 THz. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) are a kind of popular carbon nanomaterials with many functional groups that can be used in catalysis. However, in terms of calculation and simulation, most researchers choose to simplify CDs to pure graphene (GR) or graphene doped with nitrogen, boron, oxygen, and other elements due to the complexity of the calculation. In this study, the effects of adsorption of some functional groups (carboxyl, amino, and hydroxyl) on the properties of graphene have been investigated through first‐principles calculations. The calculated results suggest that the adsorbed carboxyl group on graphene is relatively unstable, while the amino and hydroxyl groups can form covalent bonds with carbon atoms on the graphene and capture some electrons. When the bi‐functional groups are adsorbed on the para or ortho position, it is beneficial for enhancing their stability on the graphene. However, when the bi‐functional groups are adsorbed on the meta position, it will reduce the stability of the functionalized graphene. This research is beneficial for evaluating the specific functional groups on the surface of CDs, and it has particular significance for the simulation and modeling of CDs. [ABSTRACT FROM AUTHOR]

Because of its excellent thermal, mechanical, and electrical properties, graphene has been used in a variety of functional coatings. Noncovalent bond functionalization and covalent bond functionalization are the most common graphene surface functionalization methods. Polymer modification, for example, can be used to give graphene and its derivatives new structure, morphology, and properties. The basic structure and predictive control principle of neural networks are discussed in this study, and a high thermal resistance porous graphene structure is reversely designed using machine learning. The effect of a graphene defect modification prediction model based on a GA (genetic algorithm) and improved BPNN (BP neural network) algorithm is investigated. The RMSE predicted by submodels 1–4 decreases by 13.26%, 3.86%, 11.71%, and 19.63%, respectively, according to the simulation results. The BPNN graphene defect modification prediction model optimized by GA has a better training and prediction effect than before optimization. [ABSTRACT FROM AUTHOR]

Self consistent charge-density functional tight binding simulations are used to investigate the effects of doping B and N atoms on structures and electronic states of armchair graphene nanoribbons passivated by H atoms at the ribbon edges. We considered ten different doping configurations of the doping ribbons, which are categorized into two groups based on whether B and N atoms are in the same carbon ring. The geometric configurations, energy, charge density differences, and Mulliken charges are characterized. The co-doping of B and N atoms in the ribbons significantly affects band structures for different doping arrangements. As covalent bonds form between B and C atoms, the Mulliken population on B atoms changes significantly when B and N atoms are located at different positions of the nanoribbons. The electrical information helps us understand how doping can adjust the electronic states of the graphene nanoribbons to meet the various requirements of electronic devices based on these nanoribbons. [ABSTRACT FROM AUTHOR]

Nitrate reduction in bio-electrochemical systems (BESs) has attracted wide attention due to its low sludge yields and cost-efficiency advantages. However, the high resistance of traditional electrodes is considered to limit the denitrification performance of BESs. Herein, a new graphene/polypyrrole (rGO/PPy) modified electrode is fabricated via one-step electrodeposition and used as cathode in BES for improving nitrate removal from wastewater. The formation and morphological results support the successful formation of rGO/PPy nanohybrids and confirm the part covalent bonding of Py into GO honeycomb lattices to form a three-dimensional cross-linked spatial structure. The electrochemical tests indicate that the rGO/PPy electrode outperforms the unmodified electrode due to the 3.9-fold increase in electrochemical active surface area and 6.9-fold decrease in the charge transfer resistance (R ct). Batch denitrification activity tests demonstrate that the BES equipped with modified rGO/PPy biocathode could not only achieve the full denitrification efficiency of 100% with energy recovery (15.9 × 10−2 ± 0.14 A/m2), but also favor microbial attach and growth with improved biocompatible surface. This work provides a feasible electrochemical route to fabricate and design a high-performance bioelectrode to enhance denitrification in BESs. [Display omitted] • Carbon felt was modified by rGO/PPy via one-step electrodeposition. • The conductivity and electrochemical activity of carbon felt were improved. • Complete denitrification was achieved at the rGO/PPy bio-cathode. [ABSTRACT FROM AUTHOR]

In the field of biomemorizers, the simultaneous enhancement of resistive switching (RS) performance and environmental robustness, and the understanding the RS mechanism involving interfacial interaction is still challengeable. Herein, the bio-composites by encapsulating graphene (GR), graphene oxide (GO) and reduced graphene oxide (RGO) into chitosan (CS) have been fabricated as memory devices with the structure of FTO/bio-composite/Ag. Among them, FTO/GO@CS(12 %)/Ag biomemorizer exhibits the best RS performance with high ON/OFF ratio (105.92), and it possesses good thermal (170 °C) and irradiation stabilities (UV exposure for 96 h). The RS mechanism is due to the migration of oxygen vacancies accompanied by formation of Ag conducting filaments in the bio-composite films. Therefore, the enhanced resistive switching performance after encapsulating into CS can be explained as the increment of defects, the higher current densities and quenched radicals. Specially, for the first time we find the presence of voltage-induced packing mode changes in GO@CS composite, which can facilitate the migration of oxygen vacancies and render its best RS performance. In all, the more carboxyl groups can strengthen the GO-CS interfacial interactions through the formation of stable hydrogen bonding network and covalent bonds, which can enhance the stabilities and makes the composites be more sensitive to electrical stimulus. The rules drawn in this work will be significant for the construction of new biomemorizers with good environmental robustness. [Display omitted] • Graphene derivants (graphene, graphene oxide and reduced graphene oxide) have been encapsulated in chitosan to construct biomemorizers. • FTO/GO@CS (12 %)/Ag biomemorizer exhibited the good RS performance with high ON/OFF ratio and excellent thermal/irradiation stabilities. • The presence of voltage-induced packing mode changes in bio-composites can facilitate the migration of oxygen vacancies. • The more carboxyl groups can strengthen the GO-CS interfacial interactions, which can enhance the stabilities and makes the composites be more sensitive to electrical stimulus. [ABSTRACT FROM AUTHOR]

Self-consistent density functional tight binding (SCC-DFTB) approaches were used to study optimized structures, energy, differential charge density, and Mülliken populations for the (8,0) carbon nanotubes (CNTs) connected to the graphene having different topology defects. Based on the calculations, nine seamless (8,0)CNT-graphenes were selected. For these connected systems, geometric configurations of the graphene and nanotubes were characterized, and the nearest neighbor length of C-C atoms and average length were obtained. The intrinsic energy, energy gap, and chemical potential were analyzed, and they presented apparent differences for different connection modes. Differential charge densities of these connection modes were analyzed to present covalent bonds between the atoms. We have also thoroughly analyzed the Mülliken charge transfer among the C atoms at the junctions. [ABSTRACT FROM AUTHOR]

Chemically bound states of benzene molecules with graphene are studied both analytically and numerically. The states are formed by switching off intrabonds of π-electrons in C6 rings to interbonds. A number of different undistorted and distorted structures are established both with aligned and with transversal mutual orientation of benzene and graphene. The vibronic interactions causing distortions of bound states are found, by using a combination of analytical and numerical considerations. This allows one to determine all electronic transitions of π-electrons without explicit numerical calculations of excited states, to find the conical intersections of potentials, and to show that the mechanism of distortions is the pseudo-Jahn-Teller effect. It is found that the aligned distorted benzene molecule placed between two graphene sheets makes a chemical bond with both of them, which may be used for fastening of graphene sheets together. [ABSTRACT FROM AUTHOR]

The robust interface adhesion between matrix and reinforcement is the guarantee for enhancing mechanical performance of the metal matrix composites (MMCs). Unfortunately, the low strengthening efficiency and drastically reduced elongation have always been the cases for MMCs due to the difficulties for architecting tightly-bonded and effective interface structure. Herein, a new strategy is proposed to construct interfacial interlocking structure in the Al matrix composites reinforced by graphene nanosheets (GNS) decorated with Ni nanoparticles (Ni NPs@GNS), which were in-situ synthesized by using assembled NaCl particles as templates. The hybrid particle of Al 3 Ni and Ni serves as an interface interlocking factor to fasten the bonding of Al and GNS, thus the outstanding load transfer and dislocation accumulation capability are adequately achieved at the interfaces. Besides, experiments and first-principles calculations disclosed that the robust covalent bonding between Ni NPs and GNS with few defects and lower oxygen level synthesized in this work facilitates a tortuous crack propagation path before fracture. Hence, the as-obtained composites exhibited an excellent strengthening efficiency while preserving a good ductility. It is evidenced that the construction of interfacial interlocking structure can pave a promising path to produce strong, tough and lightweight MMCs for wide applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Monolayer graphene flakes were dispersed at low concentrations into two achiral liquid crystals (LCs) alkoxyphenylbenzoate (9OO4) and 4-cyano-4'-pentylbiphenyl (5CB), separately. The presence of graphene resulted in two types of chiral signatures in the LCs: an electroclinic effect (a polar tilt of the LC director perpendicular to, and linear in, an applied electric field) in the smectic-A phase of 9OO4, and a macroscopic helical twist of the LC director in the nematic phase of 5CB. Graphene flakes generally possess strain chirality and edge chirality. The non-covalent interactions between the LC molecules and chiral graphene flakes induce molecular conformational deracemization in the LC, exhibiting a bulk electroclinic effect and a macroscopic helical twist. [ABSTRACT FROM AUTHOR]

Due to difficulties with scalability and practical utilization, Si/graphene composites are not yet used as anodes for commercially available lithium-ion batteries. In this paper, we report an accessible and cost-effective ball-milling route to synthesize Si and graphene composites. By introducing amino- and carboxyl-groups, covalent linkage between Si nanoparticles and graphene is created, which solves serious issues of hybrids like poor dispersion and weak connection. This composite features a unique structure, where Si nanoparticles are uniformly attached to the surface or embedded into the inter-layers of the graphene. When used as anodes of lithium-ion batteries, this composite can retain a reversible capacity of 1516.23 mAh g−1 after 100 cycles at 100 mA g−1. It also exhibited excellent ultra-long-term cycling stability and high rate performance. The electrochemical performance is superior to most reported Si/graphene composites without chemical bonds at the interface, which indicates that covalent bonding can effectively inhibit the irreversible sliding of Si nanoparticles. In addition, EIS measurement had revealed a lower transfer resistance and faster Li-ions diffusion of Si@APTES/ f -Gr, suggesting the integrity of graphene after functionalization. The proposed functionalization-assisted ball-milling approach, therefore, probably enables the large-scale production of Si/Graphene as anodes in high-performance batteries in the future. [Display omitted] [ABSTRACT FROM AUTHOR]

Sulfur represents a low‑cost, sustainable, and high theoretical capacity cathode material for lithium–sulfur batteries, which can meet the growing demand in portable power sources, such as in electric vehicles and mobile information technologies. However, the shuttling effect of the formed lithium polysulfides, as well as their low conductivity, compromise the electrochemical performance of lithium–sulfur cells. To tackle this challenge, a so far unexplored cathode, composed of sulfur covalently bonded directly on graphene is developed. This is achieved by leveraging the nucleophilicity of polysulfide chains, which react readily with the electrophilic centers in fluorographene, as experimental and theoretical data unveil. The reaction leads to the formation of carbon–sulfur covalent bonds and a particularly high sulfur content of 80 mass%. Owing to these features, the developed cathode exhibits excellent performance with only 5 mass% of conductive carbon additive, delivering very high full‑cathode‑mass capacities and rate capability, combined with superior cycling stability. In combination with a fluorinated ether as electrolyte additive, the capacity persists at ≈700 mAh g−1 after 100 cycles at 0.1 C, and at ≈644 mAh g−1 after 250 cycles at 0.2 C, keeping ≈470 mAh g−1 even after 500 cycles. [ABSTRACT FROM AUTHOR]

Graphene material has a large theoretical specific surface area, excellent theoretical conductivity and mechanical flexibility, and is a promising electrode material for supercapacitors. However, two-dimensional graphene sheets are easy to stack, which affects its electrical properties. Specifically, a sponge-like composite hydrogel for high-performance supercapacitors was prepared by onestep hydrothermal method from activated carbon and graphene oxide. Benefiting from the introduced nitrogen-containing groups and the greatly increased specific surface area, the GAC-2 nitrogen-doped activated carbon/graphene hydrogel electrode showed high specific capacitance of 505.6 F g-1. In addition, the composite hydrogel presented an excellent 3D network structure with abundant internal structural pores, in which graphene and activated carbon were cross-linked by strong covalent bonds. This unique structure greatly improves the mechanical flexibility of the composite electrode (the capacitance retention rate is approximately 87.7% after 500 bending tests). And the self-assembled flexible supercapacitor shows an energy density of 26.9 Wh kg-1 at 242 W kg-1 and outstanding capacitance retention rate of about 92.1% after 5000 charge-discharge cycles, confirming its potential application in supercapacitors. [ABSTRACT FROM AUTHOR]

The α-Ti (0001)/TiC (111) interface was studied by first-principles calculations and experiments. Two atomic terminals and four interface models have been established by first principles. Good agreement has been observed between our calculation and experimental data. Moreover, from the results of calculations, the C-termination-hollow-sited interface had the smallest interfacial distance (2.078 Å), the minimum interface energy (− 3.401 J/m2), and the largest work of adhesion (3.102 J/m2), which was the most stable. By studying the charge density, charge density difference, and the partial density of states (PDOS), Ti-C covalent bonds and Ti–Ti metallic bonds are formed across the interface, which increased interfacial bonding strength. However, the interfacial bonding is more mainly contributed from the Ti-C covalent bonds. [ABSTRACT FROM AUTHOR]

Density functional theory calculations are performed to probe reaction pathways of N2O reduction by CO molecule catalysed over Si-doped C3N (Si-C3N) nanosheets. According to our results, a single Si atom can be stabilised above the C- or N-vacancy site of C3N due to the formation of strong Si-N or Si-C covalent bonds. The reduction of N2O over Si-C3N is characterised as a two-step process. First, N2O is dissociated to N2 and an activated oxygen atom (Oads) without an energy barrier. Then, the Oads moiety is removed by CO molecule by overcoming negligible activation energy. [ABSTRACT FROM AUTHOR]

The so-called buffer layer (BL) is a carbon rich reconstructed layer formed during SiC (0001) sublimation. The covalent bonds between some carbon atoms in this layer and underlying silicon atoms makes it different from epitaxial graphene. We report a systematical and statistical investigation of the BL signature and its coupling with epitaxial graphene by Raman spectroscopy. Three different BLs are studied: bare buffer layer obtained by direct growth (BL 0), interfacial buffer layer between graphene and SiC (c-BL 1) and the interfacial buffer layer without graphene above (u-BL 1). To obtain the latter, we develop a mechanical exfoliation of graphene by removing an epoxy-based resin or nickel layer. The BLs are ordered-like on the whole BL growth temperature range. BL 0 Raman signature may vary from sample to sample but forms patches on the same terrace. u-BL 1 share similar properties with BL 0 , albeit with more variability. These BLs have a strikingly larger overall intensity than BL with graphene on top. The signal high frequency side onset upshifts upon graphene coverage, unexplainable by a simple strain effect. Two fine peaks (1235, 1360 cm−1), present for epitaxial monolayer and absent for BL and transferred graphene. These findings point to a coupling between graphene and BL. Image 1 [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) was prepared from a modified method of Hummers, then the GO was modified by γ-glycidoxypropyltrimethoxysilane (KH560) and reduced by hydrazine hydrate. The silylated reduced graphene oxide (KRGO) was obtained. The KRGO/polyurethane (PU) composites were prepared by solution mixing method using the KRGO as the filler and PU solution as the matrix. The KRGO and KRGO/PU composites were systematically characterized. The structure and morphology characterization showed that the KRGO was uniformly dispersed in PU solution by covalent bonding. The interlayer distance of the graphene increased from 0.79 to 0.95 nm after modification. The KRGO could provide a good compatibility with the PU. The thermal stabilities of the KRGO/PU composites are increased with the increasing addition of KRGO. At the KRGO content value of 1 wt.%, the thermal decomposition temperature on 10% weight loss was approximately 47 °C higher than that of the pure PU. [ABSTRACT FROM AUTHOR]

Defects can be generated when growing diamond on heterogeneous substrates. The problem dampers the widespread use of diamond films. In this paper, a novel approach is proposed which grows diamond on graphene quasi-homogeneous epitaxial substrate. Results showed that high quality diamond was synthesized on a quasi homoepitaxial graphene substrate through sp2-sp3 hybridization and covalent bond transformation. Firstly, D peak-free graphene was synthesized on nickel metal surface. C–H and C C bonds were then exploited to produce dehydrogenation and coupling reaction which caused the transform of graphene to transform into diamond. In virtue of the superior intermiscibility and catalysis of nickel to carbon, few-layer graphene grew efficiently on nickel foil surface. An internal space microstructure network of carbon atoms was produced through different non-covalent interactions. At last, graphene is converted into diamond. This process can also be used to synthesize hydrophilic porous diamond film. It is a promising approach to the development of new graphene/diamond-based components in the future. [ABSTRACT FROM AUTHOR]

The thermal decomposition on silicon carbide (SiC) is one of the most used growth techniques for fabrication of epitaxial graphene. However, it significantly diminishes graphene's otherwise exceptional carrier mobility. Reduction of the substrate influence is therefore essential for keeping conductivity at high levels. Here we present a novel technique where a sample with epitaxial graphene grown on SiC was exposed to intense 21.2 nm radiation. A sub-nanosecond pulse at low fluence in an interval 0.4–0.7 J/cm2 was used to break covalent sp3 bonds between the SiC substrate and buffer (the first graphene layer) which remains, except for release of its intrinsic strain, almost unaffected. A detailed analysis of the irradiated area examined by several microscopic and spectroscopic methods such as white-light interferometry and micro-Raman spectroscopy shows a clear evidence of a graphene layer detached from the substrate. Higher fluences induce damage to SiC substrate which expands due to the amorphization process. Damage thresholds were obtained by an advanced method of ablative imprints and compared with those calculated by the hybrid code XTANT. Image 1 [ABSTRACT FROM AUTHOR]

A new multiscale simulation method for analyzing the mechanical properties of graphene-reinforced composites is proposed. The atomistic and the macroscopic scales are combined in the proposed finite element modeling approach. In the nanoscale analysis, a space frame structure of graphene is selected, the carbon atoms are described as nodes, and the carbon–carbon covalent bonds are represented with nanoscale beams. The macroscopic homogeneous isotropic model of the matrix and the interface is included in the representative volume element of the composites. The effect of graphene volume fraction and different inclined angles on the mechanical properties of the composites is investigated under axial tension. The simulation results showed that with the increase in the graphene volume fraction, the Young's modulus of the composites was increased significantly. The Young's modulus of the composites was highly dependent on the size of graphene. The stress transfer in the interface of the composites was also analyzed using this multiscale approach. [ABSTRACT FROM AUTHOR]

Tremendous energy consumption is required for traditional artificial N2 fixation, leading to additional environmental pollution. Recently, new Li‐N2 batteries have inextricably integrated energy storage with N2 fixation. In this work, graphene is introduced into Li‐N2 batteries and enhances the cycling stability. However, the instability and hygroscopicity of the discharge product Li3N lead to a rechargeable but irreversible system. Moreover, strong nonpolar N≡N covalent triple bonds with high ionization energies also cause low efficiency and irreversibility of Li‐N2 batteries. In contrast, the modification with in situ generated Li3N and LiOH restrained the loss and volume change of Li metal anodes during stripping and plating, thereby promoting the rechargeability of the Li‐N2 batteries. The mechanistic study here will assist in the design of more stable Li‐N2 batteries and create more versatile methods for N2 fixation. [ABSTRACT FROM AUTHOR]

Topological models of graphene/CNT composite films are constructed. The films consist of tubes lying irregularly between graphene single layers parallel to them and covalently bound with graphene. The distance between the tubes is measured in graphene hexagons (H1 and H2) between ribs participating in the formation of covalent bonds. It is shown that only films based on zigzag (n, 0)-type tubes with an even number n are energetically stable. The film with the tube (10.0) and arrangement step 6/8 is most stable according to the investigations. It is found that the energy gap is present in the band structure of all studied film models and is in the range of 0.41–0.73 eV. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphene oxyfluoride films were prepared by gas-phase fluorination of graphene oxide films. • Graphene oxyfluoride films maintained their initial sizes/shapes and densely packed structures. • The composition of fluorinated films can be controlled by modulating the reaction temperature. • The films with the highest degree of fluorination exhibited the best stability in water. • Graphene oxyfluoride membranes showed similar water vapor permeabilities in comparison to graphene oxide membranes. Graphene-based films are promising candidates for filtration and separation applications due to their modulable properties, including composition, hydrophobicity, and stability. In this study, we present the preparation of graphene oxyfluoride films by gas-phase fluorination of graphene oxide layers under a dynamic flow of F 2 /N 2 gas (0.35/0.65 vol ratio) at different reaction temperatures (15 °C, 100 °C, and 200 °C). The resulting films exhibited a stable morphology, maintaining their densely packed structure and parallel arrangement of fluorinated sheets. By varying the reaction temperature, we were able to control the carbon, oxygen, and fluorine compositions, as well as the surface functional groups of the fluorinated films. Water stability tests revealed that the films fluorinated at 100 °C displayed the highest stability in water compared to other film types. This enhanced stability was attributed to the formation of strong covalent C–F bonds within the film. Furthermore, the graphene oxyfluoride membranes exhibited water vapor permeability similar to that of the original graphene oxide membrane, ranging from 8.7 to 9.1 LMH/bar. These findings demonstrate the potential of graphene oxyfluoride membranes as versatile materials for various filtration and separation applications, where the composition and stability of the membrane can be tailored to specific requirements. [ABSTRACT FROM AUTHOR]

Graphene is the strongest material ever identified. However, the fabrication of graphene-based bulk materials from graphene powders presents a significant challenge. Here, a new strategy to fabricate high performance graphene based bulk materials by introducing silicon nanoparticle is proposed. Consequently, ultra-high compressive strength and high flexural strength are achieved, measuring as high as 1102 MPa and 455 MPa, respectively. The compressive strength at the microscale even reaches a remarkable 5.17 GPa. The superior strength of the bulk material is primarily attributed to the Y-type carbon structure and Si-C bonds. The Y-type carbon structures in graphene, produced by the self-propagating high-temperature synthesis (SHS) method, and the Si-C covalent bonds formed at the interface between graphene and SiC contribute to a tight linkage of graphene sheets, thereby preventing slippage of graphene sheets. In addition, the microstructure evolution process of Si-SHS-graphene bulk material is clarified. With the introduction of silicon nanoparticles, the oxidation resistance of graphene based bulk materials is substantially improved, the weight loss is around 6% after oxidized at 1000 °C. This study carries extensive implications for understanding the impact of Y-type carbon structures and the effect of Si-C bonds in graphene-based bulk materials. [Display omitted] [ABSTRACT FROM AUTHOR]

• A double dynamically crosslinked cardanol derived epoxy vitrimer was fabricated. • The obtained vitrimers demonstrated advantages of multi-stimulus responsiveness. • Mechanical and chemical recovery, and biodegradability were revealed by the vitrimer. • The EDCS/DPTA/G composites exhibited excellent degradability in alkaline solution. Dynamic covalent chemistry provides a solution to the recycling problem of epoxy resins, and the graphene functional composites. Nevertheless, the study on chemical structures of the curing agent, and the type of dynamic covalent bonds associated with the nature of the epoxy resins still face challenge due to unclear mechanism and improper design strategy. Herein, a bio-based epoxy monomer was designed from cardanol, and used to fabricate a double dynamically crosslinked epoxy vitrimer. The mechanical properties, dynamic mechanical properties, thermal stability, relaxation behavior, self-healing efficiency, recovery, and reprocessing efficiency of the resulting resins were investigated, focusing on the effects of the soft and hard structure of the curing agent, and the types of dynamic covalent bonds. Bio-based epoxy vitrimers demonstrated several advantages, including multi-stimulus responsiveness, multi-channel self-healing ability, mechanical and chemical recovery, and biodegradability. Specifically, the epoxy vitrimers containing rigid furan rings exhibited better mechanical properties (6.85 MPa) and stability (T g = 40.81 °C) compared to those with flexible fatty chains. Additionally, the double dynamically crosslinked vitrimer showed faster stress relaxation time (5.6 min) and lower activation energy (36.58 kJ/mol) compared to systems with a single dynamic bond. Finally, the addition of graphene enabled the production of cardanol-based composites with conductivity. Overall, the ease with bio-based epoxy vitrimer and its composites with excellent degradability can be fabricated, utilized, recycled and re-used, which is a novel direction for sustainable composites. [ABSTRACT FROM AUTHOR]

193 nm Excimer lasers are efficient tools to process group-IV semiconductors for advanced microelectronic and photonic devices through crystallization annealing, or strain engineering. The combination of both, high photon energy and low penetration depth of the 193 nm laser pulses allow breaking most covalent bonds with a single photon, and low thermal budget treatments through a precise control of the laser processed volume. Up to now, studies using 193 nm lasers for silicon carbide (SiC) processing are mostly limited to ablation processes for micromachining purposes. This paper presents a first study to demonstrate that the optimization of other processes, like the creation or annealing of vacancies, the alloying of SiC surfaces or the selective ablation of silicon or carbon should also be feasible. To develop such laser assisted processes and optimize process parameters, a numerical simulation of the laser/material interaction is essential. This implies that the temporal evolution of the laser pulse must be well known, and that an "in-situ measurement" of the response of the material to the laser pulse should be available. This study therefore evaluates the temporal profile of a new high-power Excimer laser, and presents the results of in-situ Time Resolved Reflectivity (TRR) measurements obtained when irradiating 4H–SiC(0001) wafers with radiant exposures ranging from 0,1 J/cm2 to 3,0 J/cm2. The temporal pulse profile is determined, fitted and applied in a 1-D numerical simulation of the temperature gradients for Si(100) as reference sample, to validate the experimental findings. Radiant exposure thresholds at around 1,4 J/cm2 to locally produce molten surfaces and 1,8 J/cm2 to ablate and create carbon-rich regions with graphene, are determined in-situ and confirmed by Raman spectroscopy. [ABSTRACT FROM AUTHOR]

This paper summarized and collated international literatures on graphene organic anticorrosion coatings in recent ten years and hierarchical and organized knowledge structures were formed. According to the role of graphene, from the perspective of theoretical and applied research, the improvement of graphene on organic anti-corrosion coatings were reviewed. In terms of the improvement of graphene on the shielding effect of coatings, the paper discussed the dispersion methods and orientation technology of graphene. A variety of graphene dispersion methods reported in the literatures were systematically organized according to dispersant groups, modification mechanisms, dispersion mechanisms and preparation processes. In terms of functional synergy, the functionalization of graphene was divided into two aspects. They were enhancement of adhesion and self-healing of the coatings. The increase in adhesion was attributed to the covalent bonds between the functional groups on the surface of graphene and the metal matrix. In the studies on self-healing of the coatings based on modified graphene, graphene acted as the load platform for self-healing functional groups. According to the self-healing groups supported by graphene, the self-healing mechanism was divided into catalytic passivation film and corrosion inhibitor adsorption film. Then, the paper discussed the practical problems and doubts encountered in the research and application of graphene in the field of anticorrosion, and that was the local corrosion acceleration phenomenon caused by the conductivity of graphene. Meanwhile, the way to solve the promotion of local corrosion were proposed. Finally, from the macroscopic, mesoscopic and microscopic perspectives, the paper summarized and discussed the influence mechanism of graphene conductivity and its orientation on the shielding effect and cathodic protective performance of zinc-rich coatings. • International papers on graphene organic anti-corrosion coatings were reviewed. • A variety of graphene dispersion methods were systematically organized. • Enhancement of adhesion and self-healing by graphene was summarized. • Graphene-zinc coatings were reviewed from macro, meso and micro perspectives. [ABSTRACT FROM AUTHOR]

A simple route was developed to prepare graphene coating on mild steel (MS) balls by mechanical ball-milling. In order to facilitate the interface reaction, we introduced Ti layer onto the MS surface (Ti/MS) through vacuum deposition. The graphene coatings were prepared by ball-milling on a buffer Ti/MS double-layered structure, and were strongly bonded to the substrate via TiC. The corrosion rate of graphene-covered MS was only 8.2 nm day−1, which was much less than that of the bare MS (794.5 nm day−1). The corrosion resistance was up to 38676 Ω cm2, which was almost two orders of magnitude higher than that of the bare MS (369 Ω cm2). Moreover, the graphene coating demonstrated stable and long-term anticorrosive performance after 30 days immersion. The present study lights on expanding the applications of graphene coatings to a wider range. Image 1 • Graphene coating is prepared on mild steel (MS) by a ball-milling method. • Graphene coating is strongly anchored on the MS via covalent bond. • The thickness of graphene coating is 14 nm. • Graphene slows down corrosion rate reducing up to 100 times lower than that of MS. [ABSTRACT FROM AUTHOR]

Viewing the atomic-scale motion and energy dissipation pathways involved in forming a covalent bond is a longstanding challenge for chemistry. We performed scattering experiments of H atoms from graphene and observed a bimodal translational energy loss distribution. Using accurate first-principles dynamics simulations, we show that the quasi-elastic channel involves scattering through the physisorption well where collision sites are near the centers of the six-membered C-rings. The second channel results from transient C–H bond formation, where H atoms lose 1 to 2 electron volts of energy within a 10-femtosecond interaction time. This remarkably rapid form of intramolecular vibrational relaxation results from the C atom’s rehybridization during bond formation and is responsible for an unexpectedly high sticking probability of H on graphene. [ABSTRACT FROM AUTHOR]