Structural properties and hydrogen evolution reactions of predicted two-dimensional V _n C _n (n = 2, 3, 6) with first-principles calculations

Abstract

Developing stable, conductive and effective nonprecious hydrogen evolution reaction (HER) catalysts is critical to the future of the hydrogen economy. The possible structures of the two dimensional V n C n were searched with the evolutionary algorithm associated with the density functional theory (DFT) calculations. V n C n (n = 2, 3, 6) were found stable and the structures were refined with the DFT-PBE approaches at higher computational accuracies. Their thermal, dynamical and mechanical stabilities were confirmed theoretically with the same method. The electronic and the HER catalytic properties of these structures were investigated. All the structures exhibit metallicity, which is favorable to support adsorbing hydrogen atoms and transferring charges during HER. The Gibbs free energy of HER reactions support that the 2D V n C n (n = 3, 6) possess the catalytic ability of HER.