(521at) Controllable Photocatalytic Molecular Oxygen Oxidation Based on Sulfur-Containing Photosensitizers in Continuous Flow

The issues of global carbon emissions and environmental pollution are becoming increasingly severe. From the perspective of green chemistry, the use of visible light as an energy source and molecular oxygen (O₂) or ambient air as an oxidant to establish efficient and selective oxidative synthesis routes has attracted great attention. The development of efficient catalytic conversion using inexpensive and structurally simple novel visible light catalysts is an important challenge in the field of visible light catalysis. In this context, cost-effective sulfur-containing photosensitizers have recently gained increasing interest.

This study aims to carry out controllable photocatalytic molecular oxygen oxidation based on sulfur-containing photosensitizers. In the preliminary stage, selective construction of C-O, C-C, and C-N was achieved by disulfide-mediated reactions. Under continuous flow photochemical conditions, the efficiency of gas-liquid phase photocatalytic reactions was significantly improved. Currently, research is being conducted on the photocatalytic molecular oxygen oxidation of water-soluble sulfur quantum dots. Through controllable etching of sulfur quantum dots and ligand modification with specific functional structures, molecular oxygen can be progressively activated for oxidation. This enables selective C(sp³)-H oxidation reactions of important organic small molecules such as amines, alcohols, aromatics, and alkanes, as well as oxidative cleavage reactions of alkene carbon-carbon double bonds. Non-metallic pure element sulfur quantum dots are used as photocatalysts in this study to achieve efficient and highly selective molecular oxygen oxidation in aqueous solution, opening up a new approach for essential green, safe, and efficient oxidation reactions.