Insights into the reversible hydrogen storage mechanism of transition metal-decorated Irida-graphene: a DFT study

Abstract

Addressing the challenges of fuel energy requires identifying potential materials that offer high hydrogen storage ability and stability at ambient conditions, along with optimal desorption temperatures. The present study investigates TM-doped (TM = Sc, Ti, V and Nb) 2D Irida-Graphene (IG), as the possibility of potential hydrogen storage material through first-principles calculations. Among the triangular, hexagonal and octagonal carbon rings of Irida-Graphene, the TM atoms strongly bond to the hexagonal rings. It is found that 1TM can adsorb a maximum of 16H2 molecules, resulting in an average adsorption energy ranging from −0.714 (1Nb.8H2) to −0.150 (2Ti.32H2) eV/H2 and a gravimetric density ranging from 3.391 wt% (1Nb.4H2) to 21.61 wt% (2Sc.32H2). High diffusion energy barriers of 7.14 eV (Sc.IG), 7.32 eV (Ti.IG) and 7.08 eV (V.IG) prevents the clustering of TM-TM atoms. Ab-initio molecular dynamics and phonon dynamics simulations indicate stability at 450 K, above the temperature at which desorption occurs.