Oxygen Vacancies-Mediated Z-Scheme Mechanism Promotes Synergistic Photoelectrocatalysis for Hydroxyl Radical and Singlet Oxygen-Cooperating on Selective Pollutant Degradation

Achieving high effective degradation of organic pollutants in sewage having adverse effects on human health and ecosystems remains a major challenge. In this study, an oxygen vacancy (O_v)-mediated Z-scheme Co₃O₄/O_v-TiO₂ heterojunction was first reported for simultaneous selective photoelectrocatalytic pollutant degradation and hydrogen production under visible light irradiation. The optimized Co₃O₄/O_v-TiO₂ exhibited excellent photoelectrocatalytic performance in the degradation of the organic pollutants under visible light irradiation due to the formation of a Z-scheme heterojunction for the utilization of highly reductive photogenerated electrons and oxidative holes. The mechanistic investigation suggested that the synergistic effects of hydroxyl radical and singlet oxygen as the dominant reactive species facilitated the ring-open reactions of the rhodamine B for the mineralization processes. This work provides a deep understanding of designing Z-scheme heterojunction photoelectrocatalysts through defect engineering technologies for sewage treatment.