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, Co 3 O 4 -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 •O 2 − species, which can further oxidize the benzyl radical formed on the Co 3 O 4 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.