Catalytic Conversion of Styrene to Benzaldehyde over S-Scheme Photocatalysts by Singlet Oxygen

Catalytic conversion of aromatic olefins into carbonyl compounds is a critical reaction in chemical industries. Herein, we constructed a series of pyrene-alt-dibenzothiophene-S,S-dioxide (P16PySO)/tungsten trioxide (WO3) composites to investigate the mechanism of photocatalytic styrene oxidation under anaerobic and aerobic conditions. The S-scheme charge transfer pathway within P16PySO/WO3 was systematically analyzed. Under anaerobic conditions, the optimized P16PySO/WO3 photocatalyst exhibited a moderate styrene conversion rate with continuous H2 evolution. Under aerobic conditions, the activity of styrene oxidation was promoted, but H2 production was dramatically inhibited. The detection of reactive oxygen species and scavenger-assisted photocatalytic experiments revealed that triplet oxygen (3O2) could efficiently trap the energy of triplet excited P16PySO through an energy transfer process and convert to singlet oxygen (1O2). In situ diffuse reflectance infrared Fourier transform spectroscopy and density functional theory indicate that the highly reactive 1O2 plays an important role in styrene oxidation to dioxetane intermediates, realizing selective cleavage of styrene.