Mechanistic insights into dual active sites in Au@W18O49 electrocatalysts for the hydrogen evolution reaction

Abstract

Electrocatalytic hydrogen evolution reaction (HER) for water splitting is a promising approach to replace the use of fossil fuels. The high-efficiency electrocatalyst with multiple functional sites is indispensable but challenging. Herein, an urchin-like Au@W₁₈O₄₉ electrocatalyst with dual-functional sites of Au and oxygen vacancies (OVs) is employed for the enhanced HER. The Au@W₁₈O₄₉ with Au/OV ratio at 0.70 exhibits an overpotential of 79 mV at a current density of 10 mA cm⁻² and a Tafel slope of 58 mV dec⁻¹. The optimal Au/OV ratio delicately balances the generation and transformation of H* intermediates, contributing to the superior hydrogen insertion/extraction efficiency of Au@W₁₈O₄₉-0.70. The increased delocalized electronic states and synergistic co-existence of Au and OVs improved the activity and durability of Au@W₁₈O₄₉-0.70 in the HER process. The findings in this work may provide a new avenue for developing efficient and stable catalysts with multi-active sites.