Selective oxidation of benzyl alcohol into benzaldehyde over semiconductors under visible light: The case of Bi12O17Cl2 nanobelts

TLDR: In this paper, the role of active species during selective oxidation of benzyl alcohol under visible light and the design of novel visible light active photocatalysts for selective oxidization of alcohol was investigated.

Abstract: In this study we propose several criteria for semiconductor photocatalysts suitable for visible light driven selective oxidation of BA to BAD by employing several literature-reported photocatalysts (P25, g-C 3 N 4 , In(OH) x S y , Bi 3 O 4 Br, BiOBr and Cu 2 O) to oxidize BA under visible light, and then demonstrate that the selectivity of photocatalytic oxidation of benzyl alcohol is highly depended on the position of valence band of semiconductors and Bi 12 O 17 Cl 2 nanobelts could efficiently and selectively oxidize benzyl alcohol into benzaldehyde under visible light via direct hole oxidation. Although the presence of molecular oxygen and the generation of superoxide radicals are important for the selective oxidation of benzyl alcohol, the exact role of molecular oxygen is merely to trap photogenerated electrons to produce superoxide radicals during Bi 12 O 17 Cl 2 photocatalysis, which could inhibit the recombination of photogenerated charge carries, but might not be involved in the alcohol oxidation directly. The role of molecular oxygen during Bi 12 O 17 Cl 2 photocatalysis was found to be different from those of TiO 2 and g-C 3 N 4 previously reported. This study provides new physical insights for the roles of active species during selective oxidation of alcohol under visible light and the design of novel visible light active photocatalysts for selective oxidation of alcohol.