Searching for Highly Active Catalysts for Hydrogen Evolution Reaction Based on O-Terminated MXenes through a Simple Descriptor

Abstract

An efficient, earth-abundant, and low-cost catalyst for hydrogen evolution reaction (HER) is critical for sustainable hydrogen generation. In this work, we present a density-functional-theory-based screening among two-dimensional (2D) transition metal carbides (MXenes) with a fully O-terminated surface. The catalytic activity of 10 monometal carbides is first investigated, and Ti2CO2 and W2CO2 are found to be highly active catalysts for HER. Then, a volcano plot between the number of electron surface O atoms gains (Ne) and the absolute value of the free energy of hydrogen adsorption (ΔGH) is established. A simple descriptor, Ne, is thus proposed to evaluate the HER performance of O-terminated MXenes. On this basis, TiVCO2 is extracted with improved HER performance than Ti2CO2 and W2CO2 among 7 bimetal carbides. Our study provides new possibilities for cost-effective alternatives to Pt for HER, and, more importantly, develops a simple activity descriptor to efficiently search for highly active HER catalysts.