Hydrogen adsorption on vacancy-bent graphene nanosheets: A DFT study

Abstract

In this study, we have investigated density functional theory calculations on the hydrogen adsorption capacity of pristine graphene nanosheets (GNs), vacancy-bent graphene nanosheets (VGNs), and non-metal atom (boron, nitrogen) doped in vacancy-bent graphene nanosheets (Xy/VGNs, where X is boron (B) and nitrogen (N) and y = 1,2,3 i.e., number of dopant atom). According to previous studies, the presence of vacancy improves the reactivity in the graphene monolayer towards adsorbents. Engineering the vacancy-bent graphene nanostructure with an increased concentration of dopants (B/N) is found to enhance the adsorption capacity of hydrogen linearly. For B3/VGNs, N1-N3/VGNs configurations, the binding energy of hydrogen molecules lies in the useful range of −0.206 eV to −0.286 eV. Electronic property investigation reveals an indirect bandgap in VGNs and B2/VGNs, with other Xv/ VGNs retaining metallic character. The PDOS of N3/VGNs shows higher C(p)-N(p) interaction (graphene-nitrogen) at the vicinity of the Fermi level, favouring increased hydrogen adsorption. Furthermore, molecular dynamics (MD) simulation studies confirm stable adsorption of H2 with low potential energy at a higher temperature of 450 K for N3/VGNs system. This theoretical modelling suggests N3/VGNs to be the most efficient configuration with higher affinity and stability towards hydrogen molecule interaction.