In-Plane Hybrid Structure of h-BN and Graphene for Hydrogen Storage Application: A First-Principles Density Functional Theory Study

Abstract

The in-plane hybrid structure of hexagonal boron nitride (BN) and graphene (Gr) with carbon−boron and carbon−nitrogen interfaces under different boron-nitride and graphene concentrations for hydrogen storage properties is summarized in detail. The stability of these structures is verified from the cohesive energy and molecular dynamics calculations. The electronic band gap of the pristine hybrid structures is reduced with an increase in the graphene concentration. The structural properties such as bond length and bond angle are preserved for both graphene and boron nitride in the hybrid system. The pristine C−B-terminated system has an average adsorption energy of −0.046 to −0.076 eV/H 2 in the field-free condition upon dual site hydrogen molecules insertion with a theoretical hydrogen storage capacity of 10.18−10.38 wt %. In the presence of an external electric field, the adsorption energy of the hydrogen molecules linearly increases due to the polarization of the adsorbed hydrogen molecules. From our study, we report a threshold external electric field strength of ≥1.6 V/Å to achieve the lower bound criteria of average adsorption energy set by the United States Department of Energy (US-DOE) for a C−B-terminated structure and higher threshold EF for the C−N-terminated structure. While in the presence of the electric field, the average adsorption energy goes beyond −0.20 eV/H 2 with the hydrogen storage capacity of 10.18−10.38 wt % upon dual site hydrogen molecules adsorption on in-plane nBN-mGr (n = 5, 4, 3, 2, 1 and m = 1, 2, 3, 4, 5).