Single-particle catalytic monitoring of interfacial charge dynamics during light-driven CdS shell growth on Au nanocubes.

Noble metal nanomaterials, with localized surface plasmon resonance (LSPR) properties, have shown great promise in photocatalysis. However, understanding plasmon-induced interfacial charge transfer dynamics and optimizing photocatalytic efficiency remain significant challenges. Here we show the precise control of the growth of CdS shells through light-driven deposition while monitoring interfacial charge dynamics by using Au nanocubes (Au NCs) as plasmonic substrates. We discover a non-monotonic relationship between the CdS shell thickness and photocatalytic activity. An optimal shell thickness maximizes the hot-electron transfer efficiency, achieving a 2.62-fold enhancement in catalytic activity compared to bare Au NCs by effectively balancing carrier separation and recombination. Single-particle analysis, through synchronized dark-field scattering and single-molecule catalytic imaging, reveals heterogeneous catalytic behaviors associated with atomic-scale structural variations and dynamic charge transfer mechanisms. The localized electromagnetic field enhancement around Au NCs facilitates hot-carrier generation for CdS deposition, and interfacial Schottky barriers extend hot-carrier lifetimes for redox reactions. This work provides a framework for designing dynamic metal-semiconductor interfaces. It not only deepens our fundamental understanding of plasmon-induced energy conversion but also serves as a guiding principle for the development of high-efficiency solar fuel systems.