Optically Enhanced Ag@Cu₂O Core–Shell Nanoparticles for Visible Light Photocatalytic Hydrogen Evolution

Enhancing the photocatalytic activity and robustness of cuprous oxide presents key challenges in the development of efficient cuprous oxide-based photocatalysts. This report outlines a facile synthesis method for integrating plasmonic silver with a cuprous oxide semiconductor in Ag@Cu2O core–shell nanostructures with controllable shell thicknesses. Additionally, the synthesis of monodisperse spherical bare silver and cuprous oxide nanoparticles through convenient procedures is presented. The photocatalytic performances of the Ag@Cu2O and Cu2O nanoparticles for hydrogen evolution were evaluated using a custom-built photocatalytic reaction system. The results indicate that the core–shell Ag@Cu2O nanoparticles exhibit a tunable, strong absorption band within the visible spectrum and a significantly reduced electron–hole recombination rate compared to the Cu2O nanoparticles, thereby showing enhanced photocatalytic efficacy attributable to the presence of the plasmonic silver core. Notably, the Ag@Cu2O core–shell nanoparticle photocatalysts demonstrate an increase in the hydrogen evolution rate by more than 6-fold and a 21% improvement in stability compared to their Cu2O counterparts, positioning them among the top-tier cuprous oxide-based photocatalysts for hydrogen evolution.