Oxygen Vacancy-Mediated unraveling active species sources in BiO2-x Catalysts: The significance of lattice and molecular oxygen in catalytic reaction in aqueous solution

Catalytic wet air oxidation (CWAO), operating under mild conditions, presents a viable avenue for efficient organic pollutant elimination from wastewater. Metal oxide catalysts' CWAO activity depends on oxygen vacancies, but how these vacancies activate metal oxides to create reactive oxygen species (ROS) remains unclear. By modulating hydrothermal duration, we achieve variable BiO2-x vacancy levels, enabling proficient BPA degradation at approximately 60 °C. Outcomes reveal a pronounced correlation, akin to a volcanic trend, between oxygen vacancy abundance and BiO2-x catalytic activity. The principal active species originate from a cyclic process entailing lattice oxygen reaction, oxygen vacancy genesis, and dissolved oxygen supplementation. Thorough investigation, inclusive of radical trapping and electron paramagnetic resonance spectra (ESR), corroborates the pivotal role of lattice oxygen in generating OH, O2–, and 1O2. This investigation primarily aims to comprehensively explore how oxygen vacancies facilitate lattice oxygen activation and molecular oxygen filling in BiO2-x catalysts.