Dual-site oxygen activation for enhanced photocatalytic aerobic oxidation by S-scheme Ni2P/Bi3O4Br-OVs heterojunction

Solar-driven activation of molecular oxygen (O2) offers an appealing strategy to realize aerobic oxidation catalysis at room temperature, while the efficiency of photocatalytic O2 activation is severely limited by lacking O2 adsorption sites and poor carrier utilization. Herein, an efficient Ni2P/Bi3O4Br-OVs heterojunction is firstly proposed to overcome the limitation by the dual-site design of oxygen vacancies (OVs) and on Ni2P cocatalyst. By the joint observations from spectroscopic measurements and theoretical simulations, the introduction of OVs and Ni2P on Bi3O4Br nanosheets can not only optimize the light absorption, facilitate the separation and transfer of photogenerated charge carrier through the S-scheme mechanism, but also provide active sites for effective adsorption and activation of oxygen molecules, thereby contributing to highly efficient generation of •O2− radicals. Benefiting from the more oxidative active species of •O2− and h+, the Ni2P/Bi3O4Br-OVs photocatalyst achieves near-unity conversion rate and selectivity in aerobic oxidation of sulfide to sulfoxide, and it also exhibits outstanding photoactivity in the aerobic degradation of phenolic pollutants under visible light. This study showcases a feasible O2 activation approach by defect and heterojunction engineering, and provides a new perspective for designing high-performance photocatalysts in the field of aerobic oxidation catalysis.