Searching for Highly Active Catalysts for Hydrogen
Evolution Reaction Based on O‑Terminated MXenes through a Simple
Descriptor
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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 Ti<sub>2</sub>CO<sub>2</sub> and
W<sub>2</sub>CO<sub>2</sub> 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><sub>e</sub>) and the absolute value
of the free energy of hydrogen adsorption (Δ<i>G</i><sub>H</sub>) is established. A simple descriptor, <i>N</i><sub>e</sub>, is thus proposed to evaluate the HER performance of
O-terminated MXenes. On this basis, TiVCO<sub>2</sub> is extracted
with improved HER performance than Ti<sub>2</sub>CO<sub>2</sub> and
W<sub>2</sub>CO<sub>2</sub> 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