Enhanced Selective Photooxidation of Toluene to Benzaldehyde over Co3O4-Modified BiOBr/AgBr S-Scheme Heterojunction

Herein, photocatalytic selective oxidation of hydrocarbons through O-2 represents a promising way for fine chemical industry on account of its mild reaction condition. In this work, Co3O4-modified BiOBr/AgBr S-scheme heterojunction can effectively oxidize sp(3) C-H bonds at benzylic position to its corresponding aldehydes, with a toluene to benzaldehyde selectivity of 94%, which is much higher than that of pure BiOBr (21.7%) and AgBr (58.9%). A unique S-scheme charge-transfer mode is confirmed for the ternary composites by the X-ray photoelectron spectroscopy and reactive species quenching measurement. The remaining photogenerated electrons in AgBr with powerful reduction ability can react with O-2 to generate center dot O-2(-) species, which can further oxidize the benzyl radical formed on the Co3O4 surface to peroxyl radicals and then thermodynamically decompose to benzaldehyde. Herein, this work has important guiding significance for the structure regulation of photocatalysts and application in selective oxidation of sp(3) C-H bond of hydrocarbons.

Automated summary

In this study, a Co3O4-modified BiOBr/AgBr heterojunction was successfully constructed for the photocatalytic selective oxidation of sp(3) C-H bonds at the benzylic position. The resulting benzaldehyde product exhibited a high selectivity, which was attributed to the unique S-scheme charge-transfer mode. The combination of AgBr's photogenerated electrons and O-2 generated O2- radicals, which effectively oxidized the benzyl radicals on the Co3O4 surface and thermodynamically decomposed into benzaldehyde.