Copper-doped TiO₂ photocatalyst for advanced oxidation processes: reactive oxygen species generation mechanisms

Copper-doped anatase TiO₂ (Cu/TiO₂) has 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 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 Cu/TiO₂ surfaces. Under visible light irradiation, the ROS generation rates of Cu/TiO₂ are 7.2 times higher for O₂•⁻ and 11.2 times higher for •OH than those of undoped TiO₂. The superior performance of Cu/TiO₂ 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.