CdS(ZB)/CdS(WZ)/Ni-BTC photocatalytic selective oxidation of benzyl alcohol to benzaldehyde coupled with hydrogen evolution

Abstract

Development of difunctional photocatalyst for both hydrogen production and high value-added fine chemicals is of great industrial significance. Cubic crystal phase zinc blende CdS(ZB) and hexagonal crystal phase wurtzite CdS(WZ) in CdS(ZB)/CdS(WZ)/Ni-BTC (BTC = 1,3,5-benzene tricarboxylic acid) composites can form intergrowth homojunction to improve the photoelectron-hole separation efficiency, so that the composites show excellent catalytic activity in photocatalytic selective oxidation of benzyl alcohol to benzaldehyde coupled with hydrogen evolution reaction. The conversion of benzyl alcohol can up to 99.0%, the yield of benzaldehyde is 90.2%, and the yield of hydrogen is 2.891 mmoL·g−1·h−1. Meanwhile, styrene was reduced by hydrogen produced via photocatalytic oxidation benzyl alcohol using D2O as reaction solvent. The results demonstrate clearly that 41.6% of H2 come from benzyl alcohol, and 58.4% of D2 come from D2O by analysis of the benzene ethane product. The catalytic mechanism is speculated to be that the benzyl alcohol can simultaneous produce benzaldehyde and H2 by holes oxidation and dehydrogenation, and electron reduce the intrinsic hydrogen ion in water to H2. These results enrich the mechanism of photocatalytic benzyl alcohol oxidation coupled with hydrogen evolution, and provide a new experimental and technical strategy for the design and synthesis of dual-function photocatalysts.