Evaluation of hydrogen storage capacity of two-dimensional Sc2N MXene: A DFT study

Abstract

In this work, the efficiency of hydrogen storage on Sc2N MXenes monolayer is systematically investigated using first-principles calculations. After determining the structural stability of designed monolayer, adsorption sites for the storage of hydrogen atoms (H) and molecules (H2) are identified. The calculated binding energies have indicated that the hydrogen atoms have favorable adsorption at the center or H site of the Sc atoms and hydrogen molecules are found to be the most stable when adsorbed on the top/T site of Sc atoms. The binding energy assessment identified the chemisorption for hydrogen atoms and Kubas-type interactions for H2. To further ascertain the suitability of the Sc2N monolayer for hydrogen storage various analyses including binding energy, partial density of states (PDOS), electron localization function (ELF), Mullikan charge analysis and Hirshfeld charge analysis are conducted. In order to determine the thermal stability of the Sc2N monolayer, desorption temperature with respect to pressure and molecular dynamics study has also been conducted and found the monolayer thermally stable. Desorption isotherms condition with increasing pressure confirms the gravimetric storage uptake. The obtained results have revealed that the hydrogen storage capacity considered monolayer has reached up to 10.8 wt%, which is reasonably high. Hence, the obtained results of hydrogen atom and molecules adsorption have clearly established that Sc2N monolayer is as an exemplary, stable, reliable and efficient medium for hydrogen storage applications.