Insightful understanding of hot-carrier generation and transfer in plasmonic Au@CeO₂ core–shell photocatalysts for light-driven hydrogen evolution improvement

Plasmonic metal@semiconductor core–shell nanoparticles (CSNPs) are considered as promising candidates for artificial photosynthesis. Herein, Au@CeO₂ CSNPs are hydrothermally fabricated for photocatalytic hydrogen evolution reaction (HER). CSNPs deliver superior HER performance compared to free CeO₂. In particular, Au@CeO₂-18 model (shell thickness of 18 nm) produces an HER rate of 4.05 μmol mg^–1 h^–1, which is ∼10 times higher than that of pure CeO₂ (0.40 μmol mg^–1 h^–1) under visible-light. Additionally, Au@CeO₂-18 photocatalyst demonstrates long-term stability after five repetitive runs, at which point it only loses approximately 5% of the activity, while core-free CeO₂ decreases by 37.5 %. Such improvements are attributed to the electronic interactions between Au and CeO₂, which not only enriches Ce³⁺ active sites to narrow bandgap of ceria toward visible, but also increases the affinity for hydrogen ions on the CSNPs surface. Moreover, localized surface plasmon resonance is light-excited and decays to efficiently produce hot-carrier to drive catalytic reactions.