Basal plane activation of two-dimensional transition metal dichalcogenides via alloying for the hydrogen evolution reaction: first-principles calculations and machine learning prediction

Abstract

Two-dimensional transition metal dichalcogenides (2D TMDCs) show promise as potential inexpensive electrocatalysts for the hydrogen evolution reaction (HER). However, their performance is bottlenecked by the inertness of the basal plane. The present study demonstrates alloying as a viable route to address such limitations. A machine learning workflow based on density functional theory (DFT) calculations has been established to predict the HER activity and stability for a series of 2D cation-mixed TMDC alloys of various compositions. The results showed that alloying exhibits a substantial effect in reducing the Gibbs free energy of hydrogen adsorption (ΔG_H) on the basal plane, able to render optimal ΔG_H for the HER for certain TMDC alloys. The stability prediction of these TMDC alloys further showed their potential to be synthesized in experiments. The mechanism underlying this alloying induced basal plane activation originates from the electronic effect, in particular the p-band shifting, resulting from the chemical composition variation. The findings are expected to serve as guidance for the rational design and discovery of TMDC alloys for catalytic applications.