In situ detection of hot-electron-induced photocatalytic reduction using Au@Ag, Au@Ag2S, and Au@SiO2 core-shell nanoparticles

Noble-metal-based surface-enhanced Raman spectroscopy (SERS) substrates can be employed as catalysts capable of generating hot electrons to drive chemical reactions of target molecules adsorbed on their surface. However, the localized surface plasmons excited from pure noble metals generally exhibit relatively low hot-electron utilization efficiency with the reactants owing to charge carrier recombination. This problem can be solved by integrating heterogeneous structures with the noble metal. Herein, we describe the fabrication of bifunctional SERS substrates by constructing Au@Ag, Au@Ag 2 S, and Au@SiO 2 core-shell nanoparticles and evaluate the effects of the three heterostructures (Au cores encapsulated by shells composed of metal, semiconductor, or insulator) on the hot-electron transfer efficiency by in situ monitoring of the catalytic dimerization of p -nitrophenol to form p , p ′-dimercaptoazobenzene under 632.8 nm laser illumination. The developed SERS strategy opens up new opportunities for exploring hot-electron-induced reactions as well as providing a useful reference for photocatalyst selection.