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 (<i>N</i>_e) and the absolute value of the free energy of hydrogen adsorption (Δ<i>G</i>_H) is established. A simple descriptor, <i>N</i>_e, 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