A DFT study of hydrogen storage of a novel 2D m-BC nanosheet

Abstract

Li and Ti are studied for decorating two-dimensional (2D) porous boron-carbon monolayers (m-BC) via density functional theory to enhance hydrogen adsorption. All possible adsorption sites are tested, and the Li and Ti atoms on the pristine m-BC prefer to remain at the centre of the eight-numbered ring. The binding energies of Li and Ti are -3.93 and -7.83 eV, respectively. Furthermore, both the Li and Ti atoms can adsorb a maximum of five hydrogen molecules. The average adsorption energy of the hydrogen molecules on Li- and Ti-decorated structures is -0.21 and -0.41 eV, respectively. The hydrogen storage capacity is 11.79 and 7.97 wt% for Li- and Ti-decorated m-BC, respectively, which meets the US Department of Energy (DOE) target. According to the Bader charge analysis, electrons are transferred from the metal atoms to the m-BC structure. The polarization mechanism increases the hydrogen adsorption capacity. This study proves that Li- and Ti-decorated m-BC can be useful in developing hydrogen storage media.