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[Display omitted] • Single atom Co-anchored nitrogen‑doped graphene was developed for PMS activation. • 1O 2 generation was boosted in PMS activation and dominant for pollutant degradation. • The acute toxicity of pollutants was effectively reduced in PMS activation. • Developed catalyst exhibited remarkable cycling stability and negligible leaching. Singlet oxygen (1O 2) is an excellent active species generated in advanced oxidation processes (AOPs) that exhibits high selectivity, long life and wide pH tolerance. Therefore, catalysts for highly efficient and selective generation of 1O 2 in AOPs would be highly desirable. This study developed a single atom Co-anchored nitrogen‑doped graphene (Co SAC -NG), which showed excellent catalytic performance for peroxymonosulfate (PMS) activation and bisphenol A degradation, with the pseudofirst-order reaction rate constant improved from 8.13 × 10−4 min−1 without catalyst to 4.42 × 10−2 min−1 with 5 mg L−1 Co SAC -NG. Mechanism studies indicated that Co SAC -NG selectively enhanced 1O 2 generation, which was the dominant active specie for pollutant degradation. Moreover, the Co SAC -NG/PMS system effectively reduced the acute toxicity of pollutant, and Co SAC -NG exhibited remarkable cycling stability and negligible leaching. This study develops a new catalyst with high selectivity for 1O 2 generation and provides a reference for application of single atom catalyst in PMS-based AOPs. [ABSTRACT FROM AUTHOR]

Cross-planar di-vacancies (CPDVs) within stacked graphene hexagonal boron nitride ( h -BN) heterostructures provide stabilized covalent links to bridge adjacent graphene and h -BN sheets. Through a first principle theoretical study based on density functional theory (DFT), it was shown that the CPDVs serve as focal points for cross-planar atom diffusion between graphene and h -BN, and the chemical nature of interlayer links along with associated cross-planar migration pathways at these defects can be predictively manipulated through modulation of the chemical environment and charge engineering, to achieve consistent B or N doping and simultaneous healing of graphene. The present study proposed a viable approach integrating irradiation, chemical and charge engineering, to produce high-quality graphene with tunable electronic and electrochemical properties, using the h -BN substrate. [ABSTRACT FROM AUTHOR]

In the current study, the stability of a functionally graded annular plate reinforced with a limited content of graphene platelets (FG-GPLRC) resting on a two-parameter elastic foundation is investigated. The structure is under the coincident effect of radial compressive forces and inertial load due to angular velocity. It is considered that the GPL nanofillers are randomly oriented, and their weight fraction varies with a layer-wise pattern through the thickness direction. The equivalent Young's modulus and other material properties of the annular FG-GPLRC plate are evaluated by utilizing the Halpin–Tsai micromechanics rule. It is considered that the plate is resting on a two-parameter elastic foundation. The governing equations are extracted based on the first-order shear deformation theory (FSDT) and the von-Kármán type of geometric nonlinearity. Applying the virtual work principle and the adjacent equilibrium standard, the plate's equations of stability are established. The derived governing equations are solved using a combined analytical–numerical (TE-GDQ) method, including trigonometric expansion in the circumferential direction and the generalized differential quadratures method through the radial direction. Comprehensive novel numerical results is derived to evaluate the effect of weight fraction of nanoparticles, the type of FGM, geometric dimensions, various boundary conditions, and surrounding elastic foundation on the buckling behavior of the plate. • Mechanical and rotating bifurcation stability of annular plates reinforced with GPL. • GDQ method to obtain the response of governing equilibrium equations. • Second-order correlation homogenization technique to extract effective properties. • FSDT and von-Karman nonlinear relations to obtain the equilibrium equations. • The adjacent equilibrium criterion to distinguish the primary and secondary. [ABSTRACT FROM AUTHOR]

Lattice trapping is an important aspect in accurately understanding the fracture behaviors of nanomaterials. Employing molecular dynamics simulations, we studied the lattice trapping of nanocracks in both single-crystal and polycrystalline graphene. Different crack-dislocation and crack-grain boundary configurations were constructed and investigated. It is found that cracks in single-crystal graphene exhibit negligible lattice trapping, with or without the presence of dislocations. On the other hand, lattice trapping in polycrystalline graphene may vary greatly and is shown to be directly correlated to the tensile strength of grain boundary. Moreover, we showed that unique dislocation-independent traction-separation behaviors, which are not affected by the presence of dislocations, exist for cracks in single-crystal graphene. The traction-separation relation was then fitted to a cohesive zone model to demonstrate the possibility of bridging atomistic modeling with large-scale numerical simulations. Our findings provide critical hints for atomistic-informed multiscale modeling of fracture of two-dimensional materials. [ABSTRACT FROM AUTHOR]

The electronic and thermoelectric properties of a new carbon bulk material, three-dimensional (3D) graphene, are investigated in this study. Our results show that 3D graphene has unique electronic structure, i.e., near the Fermi level there exist Dirac cones. More importantly, the thermoelectric performance of 3D graphene is excellent, at room temperature the thermoelectric figure of merit (ZT) is 0.21, an order of magnitude higher than that of graphene. By introducing line defects, the ZT of 3D graphene could be enhanced to 1.52, indicating 3D graphene is a powerful candidate for constructing novel thermoelectric materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Using large-scale molecular dynamics (MD) simulations in conjunction with continuum modeling, the deformation behaviors of three-dimensional (3D) graphene honeycomb structures under uniaxial in-plane compression have been systematically investigated. The stress-strain responses of graphene honeycombs were found to be dependent on the loading direction, prism size and lattice orientation, but little affected by the junction type. Two critical deformation events, i.e., elastic buckling and structural collapse, were identified, with the associated local and global structural changes associated at these critical events clarified. Continuum models accounting for the effect of lattice orientation and size-dependent yielding have been developed to quantitatively predict the threshold stresses for those critical deformation events. In addition, it has been demonstrated that the overall stress-strain curve of graphene honeycomb can also be reasonably well predicted via continuum modeling, albeit deviation at large strains due to effect of junction on cell wall bending. The present study provides critical mechanistic understanding and predictive tools for optimizing and designing 3D graphene honeycombs in small-scale applications. [ABSTRACT FROM AUTHOR]

Hydrogenation is a viable approach in transforming two-dimensional (2D) nanosheets into three-dimensional (3D) nanoarchitectures. The present work reported self-folding of 2D graphene into 3D graphene Miura origami assisted by hydrogenation, and studied its Poisson's ratio under external strain using molecular dynamics simulation and continuum modeling. It was found that the graphene Miura origami possesses negative Poisson's ratio, being largely insensitive to the chirality of the folding creases and side lengths of the constituting parallelograms. We further demonstrated the good agreement of Poisson's ratio between the continuum prediction and MD simulation, and identified the origin of their deviation as localized stress concentration at the quad-junction of the graphene Miura origami. The present study provides insights into designing novel 3D nanoarchitectures of programmable functionalities from 2D nanomaterials. • Self-folding of graphene into graphene Miura origami was achieved by selective hydrogenation. • Poisson's ratio behavior was systematically studied by molecular dynamics simulation and continuum modeling. • Effects of chirality of folding, side lengths of constituting parallelograms, and local deformation were clarified. [ABSTRACT FROM AUTHOR]

Li-ion capacitors (LICs) are considered a bridging electrochemical energy device between Li-ion batteries and supercapacitors. Graphene nanoplatelet (GNP)‑carbon nanotube (CNT) hybrid materials can be a good candidate for negative electrode materials used in LICs. The rate performance of LIC negative electrodes plays a key role in increasing the power density of LICs. In this study, the Li storage kinetics of a GNP-CNT hybrid electrode was investigated. CNTs were directly grown on the GNP surfaces through chemical vapor deposition via transition metal oxide seeding. Natural graphite, GNP, and mixture (GNP and CNT) electrodes were used as the control electrodes. The kinetics was evaluated using electrochemical analysis tools such as galvanostatic charge-discharge cycling at various current densities, cyclic voltammetry, galvanostatic intermittent titration technique, and electrochemical impedance spectroscopy. The results revealed that the direct growth of CNTs on the GNP surfaces led to strong contact between these materials. This contact could play a pivotal role in the improvement of reversible Li storage kinetics characterizing negative electrodes for high-power LICs. • Carbon nanotubes (CNTs) were directly grown on graphene nanoplatelets (GNPs) through chemical vapor deposition. • Electrochemical Li storage kinetics of the GNP-CNT hybrid electrode was investigated. • The strong contact between CNTs and GNPs plays a pivotal role in the improvement of kinetics. [ABSTRACT FROM AUTHOR]