A Single Atom Cu/TiO2 Photocatalyst for Advanced Redox Processes: Reactive Oxygen Species Generation Mechanisms

Single-atom catalysts (SACs) of copper dispersed in anatase TiO2 (Cu/TiO2) have attracted significant attention in various sustainable chemical processes, including water splitting, carbon monoxide oxidation, carbon dioxide reduction, chemical synthesis, and advanced oxidation processes for water treatment. Reactive oxygen species (ROS) are involved in these processes, but a mechanistic understanding of ROS generation on Cu/TiO2 SAC surfaces has not been established. Combining experimental investigation and computational simulation, this work provides unequivocal evidence for superoxide radical anion (O2•–) formation via reduction of the adsorbed oxygen by Cu+ and hydroxyl radical (•OH) production by oxidation of lattice oxygen within the bridging Cu-O-Ti structure on the SAC surface. The superior performance of the SAC has been demonstrated through its organic dye degradation, bactericidal activity, and biofilm disruption, indicating its wide applicability in water treatment and disinfection. The results and the methodologies will benefit the wide field of heterogeneous redox chemistry.