Plasmonic metal–semiconductor nanostructure photocatalytic water splitting has attracted extensive attention owing to its bright future in using visible light. However, the role of semiconductor defects in modulating the carrier dynamics and charge transfer pathways within these nanostructures remains unclear. Herein, Au@CdS nanoparticles were employed as a model catalyst for the photocatalytic hydrogen evolution reaction (HER), and the effect of sulfur (S) vacancy type on plasmon-enhanced photocatalysis was investigated. Spectral and theoretical analyses revealed that surface S vacancies in untreated samples serve as adsorption sites for H2O adsorption, while interfacial S vacancies facilitate carrier separation and the transfer of photogenerated electrons from CdS and plasmon-induced hot electrons generated via Au interband transition to surface reactive sites, enhancing Au@CdS photocatalytic activity under short-wavelength light. In contrast, treated samples with fewer interfacial vacancies and improved crystallinity exhibit reduced recombination, prolonged carrier lifetimes, and more efficient hot-electron utilization via Au intraband transitions, resulting in superior performance under long-wavelength light. Finally, by integration of low-S-vacancy Au@CdS (Au@CdS(L)) with S-rich-vacancy CdS (CdS(R)) into a Au@CdS(R-L-R) sandwich nanostructure, the visible-light photocatalytic HER activity was considerably improved. These findings not only advance the understanding of defect-mediated plasmonic photocatalysis but also offer a general strategy for the design of high-performance plasmonic photocatalysts.
Du et al. (Fri,) studied this question.