Cobalt Porphyrazine Supported on SnO₂ with Oxygen Vacancies for Boosting Photocatalytic Aerobic Oxidation of Glucose to Organic Acids in an Aqueous Medium

There is increasing interest in the production of value-added chemicals by oxidizing glucose with the aid of photocatalysis in an aqueous medium. Herein, a new SnO₂-OVs/CoPz composite was prepared through cobalt tetra­(2,3-bis­(butylthio)­maleonitrile)­porphyrazine (CoPz) supported on SnO₂ with oxygen vacancies (SnO₂-OVs), and the as-prepared SnO₂-OVs/CoPz composite exhibited strong visible-light absorption and excellent charge separation efficiency. The SnO₂-OVs/CoPz composite possessed a stronger adsorption ability toward glucose, while the composite possessed a moderate adsorption ability toward organic acid. Therefore, the SnO₂-OVs/CoPz composite showed excellent photocatalytic activity for oxidizing glucose to organic acid in an aqueous medium, using atmospheric dioxygen as an oxidant under simulated sunlight irradiation. Various kinds of organic acids including glucaric acid, gluconic acid, and formic acid were acquired through this composite photocatalytic system. The synergy of SnO₂-OVs and CoPz accelerated the glucose oxidation. The total selectivity toward the above three organic acids can reach up to 81.5% at 43.6% glucose conversion after reacting for 3 h under optimal conditions, especially 28.5% selectivity toward glucaric acid was acquired in an aqueous medium. The effects of various active species on glucose oxidation were further revealed by scavenger experiments and ESR detections. This work provides a strategy to fabricate new photocatalysts for efficient organic transformation.