Extracting hot holes from plasmonic semiconductors for photocatalysis

We achieved efficient hot hole collection via interfacing plasmonic CuS nanoplatelets with a suitable p-type semiconductor for the first time. The approach we applied was to rationally select a semiconductor (herein, BiOCl) such that it has a suitable band structure to prevent the hole loss from CuS in the dark, while allowing the hot hole injection from the plasmon-excited CuS under illumination. The resultant, efficient hot hole injection was then verified by our systematic measurements along with theoretical modelling. We showed that the transversal mode dominates the hot hole generation and has a greater contribution to photocatalysis than the longitudinal mode. We then elaborated on an optimal CuS/BiOCl composite configuration allowing for efficient hot hole collection in near-infrared photocatalysis. This work demonstrates the feasibility of harvesting hot holes from plasmonic semiconductors and opens a new route for the rational design of broadband and cost-effective plasmonic photocatalysts.