Reversible hydrogen storage behaviors of Ti2N MXenes predicted by first-principles calculations

Abstract

The hydrogen storage behaviors of the nitride-based MXenes Ti2N have been investigated by performing density functional calculations. It is observed that H2-molecules could be adsorbed on and desorbed from Ti2N monolayer with suitable adsorption strength under ambient conditions. Moreover, the stability and hydrogen adsorption behaviors are analyzed by computing adsorption energy, charge population and ab initio molecular dynamic simulations. The Kubas-type interaction of the H2-molecules with Ti2N monolayer is investigated according to the charge transfer and electronic projected density of states. Specifically, it is found that the maximum hydrogen storage capacity of Ti2N reaches up to 8.555 wt%, in which the reversible hydrogen storage capacity is of 3.422 wt%. In addition, OH-group-decorated Ti2N has great advantages on hydrogen storage, and the reversible hydrogen storage capacity is of 2.656 wt%. Therefore, the 2D Ti2N MXenes are expected for a potential candidate as reversible hydrogen storage materials under ambient conditions.