The Metal Type Governs Photocatalytic Reactive Oxygen Species Formation by Semiconductor-Metal Hybrid Nanoparticles

Semiconductor-metal hybrid nanoparticles (HNPs) are promising photocatalysts for redox reactions, including water reduction for hydrogen generation and reactive oxygen species (ROS) formation. Herein we study the effect of the metal co-catalyst type on the light-induced ROS formation using a combination of spectrophotometric and fluorescence assays, as well as electron paramagnetic resonance spectroscopy. We find that although Pt tips are more efficient for H₂ generation, hydrogen peroxide and hydroxyl radicals are formed more effectively by Au tipped HNPs. These variations are attributed to the different surface reactivity and selectivity related to the metal tip composition. The obtained understanding contributes to the optimal design of these hybrid nanosystems as photocatalysts in various ROS-driven applications such as photopolymerization, and environmental and biomedical scenarios.