Effects of Charge, Dopant, and H Saturation on the Hydrogen Evolution Activity of Au ₂₅ -Based Thiolate-Protected Nanoclusters

This study examines the effects of charge, dopant type, and hydrogen saturation on the hydrogen evolution reaction (HER) activity of thiolate-protected Au25-based nanoclusters using density functional theory (DFT). By extending the analysis to include up to 10 hydrogen atoms, this work captures the behavior of these nanoclusters under realistic HER reaction conditions, providing a broader understanding of the catalytic properties. Our findings, supported by Pourbaix diagrams, reveal that high hydrogen coverages dominate under HER-relevant potentials. Pt- and Pd-doped clusters exhibit remarkable structural stability, retaining their icosahedral core even at high hydrogen coverage. The detachment of thiol (HSR) and HAu-S(R)H molecules creates more accessible active sites enhancing catalytic efficiency. These clusters also support low H (2H) coverage states at less negative potentials, further contributing to their promising catalytic activity reported in the experimental literature. In contrast, Cu-, Ag-, Zn-, Cd-, and Hg-doped clusters undergo structural collapse of the icosahedral core as hydrogen coverage increases and stabilize only high coverage clusters (>7H), correlating with their lower reactivity observed experimentally. These results highlight the critical role of dopant-induced structural and electronic dynamics in governing HER pathways and provide new insights into designing efficient nanocluster catalysts for sustainable hydrogen production.