Responses to comments on the paper “two-dimensional Sc2C: A reversible and high capacity hydrogen storage material predicted by first-principles calculations”

Abstract

A recent commentary by Santhosh and Ravindran on our paper (Int. J. Hydrogen Energy 2014, 39:10,606) demonstrated that the interaction between H 2 and MXene (Sc 2 C and Ti 2 C) phases are not Kubas-type and should be of weak physisorption, and thus made a conclusion that 2D Sc 2 C and Ti 2 C are not suitable for practical hydrogen storage applications. In this responses, we recalculated hydrogen adsorption on 2D Sc 2 C and Ti 2 C by using different exchange-correlation functionals. And based on the calculated results, bare MXenes (especially the Ti 2 C) are suitable as hydrogen storage materials at temperatures of several tens degrees lower than room temperature. And the hydrogen adsorptions on the MXenes terminated with oxygen group were also investigated. Among the Ti 2 C, Sc 2 C and their oxygen-functional counterparts, the binding energy of H 2 on Sc 2 CO 2 surface is the closest to the ideal range of 0.16–0.42 eV/H 2 at ambient conditions, and thus the Sc 2 C with oxygen group is expected to be more suitable as hydrogen storage materials.