Gold cluster decorated MoS2 monolayer for enhanced hydrogen evolution reaction: A DFT investigation

Abstract

2D MoS₂ has emerged as a promising and cost-effective electrochemical catalyst. While the basal planes of 2D MoS₂ are intrinsically inert for the hydrogen evolution reaction (HER), its overall activity can be improved by decorating the surface with small gold clusters. Here, we used dispersion-corrected density functional theory to systematically investigate the structural, electrical, and catalytic properties of gold atom clusters containing one to four atoms decorated on MoS₂ monolayers (Au_n@MoS₂, n = 1–4). Our findings unveil that Au_n@MoS₂ systems are energetically stable, with negative binding energies. The decoration with Au clusters reduces the band gap, enhances charge transfer ability, and improves HER activity compared to pristine MoS₂. Among the studied systems, Au₃@MoS₂ at all three Au sites and Au₄@MoS₂ at one Au site exhibited the best HER performance, with near-zero Gibbs free energy values for hydrogen adsorption. The HER activity trend suggests that while larger Au_n clusters generally offer more active sites, Au₃@MoS₂ outperforms Au₄@MoS₂, emphasizing the role of suitable Au–Mo ratio and Au content. This study highlights Au₃@MoS₂ and Au₄@MoS₂ as stable and efficient catalysts for HER, offering a viable strategy to enhance the catalytic performance.