V2N MXene for Hydrogen Storage: First-Principles Calculations

Hydrogen has emerged as a green and sustainable alternative renewable energy source for fuel cells. Recently, MXenes have been proposed as versatile materials for hydrogen storage and various energy-related applications. Herein, monolayer and bilayer V2N MXenes have been studied for hydrogen storage performances through first-principles computations. The structural stability and electronic properties like bandgap and density of states of V2N MXene are first investigated using density functional theory calculations. Monolayered V2N MXene exhibits average adsorption energy between −0.80 and −0.32 eV, whereas bilayered V2N shows values between +0.27 and −0.35 eV for Y and Z adsorption sites. Further, Kubas interaction has been observed for both MXene structures at Y and Z sites through adsorption energy and projected density of states analyses. The calculated gravimetric storage capacity for monolayer and bilayer V2N is 6.86 and 5.45 wt %, respectively. All of the H2 adsorbed on both monolayer and bilayer V2N MXene structures is exclusively attributed to the Kubas interaction. This finding indicates that the reversible capacity for hydrogen storage in the V2N monolayer is 6.86 wt %, while for the V2N bilayer, it is 5.45 wt %. These findings indicate that V2N MXene exhibits strong potential as a versatile material for hydrogen storage.