Selective Photocatalytic CC Coupling of Bioethanol into 2,3‐Butanediol over Pt‐Decorated Hydroxyl‐Group‐Tunable TiO2 Photocatalysts

Abstract 2,3‐Butanediol (2,3‐BD) was synthesized through TiO 2 ‐photocatalytic CC coupling of bioethanol synchronously with the liberation of an energy H 2 molecule in an anaerobic atmosphere. It was found that the selectivity of 2,3‐BD is controlled by the amount of . OH. The less the . OH, the higher the 2,3‐BD selectivity. Furthermore, it was revealed that the amount of . OH increases with the increasing of the surface OH groups on TiO 2 photocatalyst. The introduction of water is in favor of the CC coupling pathway. This can be attributed to the stronger interaction between water and TiO 2 , which is beneficial to recovering the OH groups and promoting the desorption of . CH(OH)CH 3 intermediates, thus suppressing the thermodynamically favorable overoxidation of . CH(OH)CH 3 into acetaldehyde and promoting the CC coupling into 2,3‐BD. Based on the findings, the 2,3‐BD selectivity was greatly enhanced from approximately 2.6 % to approximately 65 % over Degussa P25‐TiO 2 photocatalyst through fluorine substitution of surface OH groups.