Selective Photocatalysis of Benzyl Alcohol Valorization by Cocatalyst Engineering Over Zn₂In₂S₅ Nanosheets

Abstract

Photocatalytic conversion of benzyl alcohol (BA) is a promising means to coproduce H2 with value‐added chemicals. However, there is a lack of an efficient strategy to regulate the selectivity of the BA conversion products. Here, by a simple cocatalyst engineering technique, the selective conversion of BA over Zn2In2S5 nanosheets (ZIS) is maneuvered. Two types of cocatalysts, i.e., Pt and Cd, are photo‐deposited onto ZIS that can shift the selectivity to diverse products, namely, Pt to benzaldehyde (BAD) and Cd to the carbon‐carbon (C─C) coupling compounds. Mechanistic studies indicate that Cd has a high reducing capacity to convert BAD back to the ketyl radical (C𝛼 radical), favoring the construction of the C─C bonds. Pt, however, facilitates the generation of C𝛼 radicals but is energetically unfavorable for their coupling reactions, resulting in the generation of BAD as the main product. Theoretical calculation reveals that the distinct catalytic behaviors of Pt and Cd stem from their different electronic structures that govern the adsorption strength to the reaction intermediates and the reaction energy barriers of the C─C coupling step. This work not only addresses the challenge of selectivity regulation for BA conversion but also brings fresh mechanistic insights into the role of the cocatalysts.