Xiaohan Bie

Abstract 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.

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, al...

Two-dimensional transition metal dichalcogenides (2D TMDCs) have attracted tremendous interest as one prominent material group promising inexpensive electrocatalysts for hydrogen evolution reaction (HER). In the present study, using monolayer MoTe2 as a representative, we demonstrated that phase boundaries can provide a viable pathway to activate the basal plane of 2D TMDCs for enhanced HER performance. Comprehensive first-principles calculations have been performed to examine the energetics and structural stabilities of possible 2H/1T’ phase boundary configurations. Three categories of sites, Te, Mo and hollow sites, have been identified in energetically stable phase boundaries, as potential catalytic centers for HER, all indicating enhanced HER activity than the pristine basal lattice. In particular, the hollow sites, a new group of sites induced by phase boundaries, show great promise by exhibiting a Gibbs free energy near the thermoneutral value for hydrogen adsorption, comparab...