Combinatorial selective synthesis and excitation experiments for quantitative analysis of effects of Au on a semiconductor photocatalyst

Despite its chemical stability, Au can significantly augment the catalytic properties of heterogeneous photocatalysts owing to its excellent optical properties in the visible region and localized surface plasmon resonance at the nanometer scale. However, experimental demonstration and quantitation of Au-semiconductor electron/energy-transfer pathways remain challenging. Herein, we report an optical microscopy-based combinatorial synthesis and excitation strategy to study Au@Cu₂O plasmonic nanocatalysts under light irradiation at the single-particle level. Moreover, we studied the reaction kinetics of the hybridized catalyst, a property that is often difficult to investigate among the other parameters of molecular transport, and measured the individual contributions of the plasmon and excitation effects toward the intrinsic catalytic efficiency. Based on this, we propose an electron-transfer mechanism for Au-semiconductor nanoparticles. This simple and systematic strategy is a better alternative to the conventional electron microscopy technique and aids in investigating chemical reactions at the single-molecule and single-particle level.