Constructing a system for effective utilization of photogenerated electrons and holes: Photocatalytic selective transformation of aromatic alcohols to aromatic aldehydes and hydrogen evolution over Zn3In2S6 photocatalysts

In a reaction system, the simultaneously efficient utilization of photogenerated electrons and holes to realize the photocatalytic selective redox reactions of organics has been a hot topic. In this paper, the Zn3In2S6 samples were synthesized via a simple solvothermal method with different solvents, which could make full use of photogenerated electrons and holes to achieve the photocatalytic selective transformation of aromatic alcohols to aromatic aldehydes and hydrogen evolution under mild conditions. The results show that the Zn3In2S6 synthesized with water (Zn3In2S6-W) exhibits the highest photocatalytic performance among the selected samples, with which the yields of benzaldehyde and hydrogen reach up to 732 and 708.8 μmol under light irradiation (λ ≥ 380 nm) for 4 h, respectively. The molar ratios between aldehydes and hydrogen are close to 1: 1. The apparent quantum efficiency is about 6.48% for wavelength λ = 380 ± 10 nm over Zn3In2S6-W sample. A possible reaction mechanism for the photocatalytic selective transformation of benzyl alcohol to benzaldehyde and hydrogen evolution under light irradiation is proposed. This work highlights that a reaction system is developed to effectively make use of the photogenerated electrons and holes for selective transformation of aromatic alcohols to aromatic aldehydes and hydrogen evolution over Zn3In2S6 photocatalysts under mild conditions.