Defective ZnIn<sub>2</sub>S<sub>4</sub> Nanosheets for Visible-Light and Sacrificial-Agent-Free H<sub>2</sub>O<sub>2</sub> Photosynthesis via O<sub>2</sub>/H<sub>2</sub>O Redox
Huiping Peng, Hongcen Yang, Jiajia Han, Xiaozhi Liu, Dong Su, Yang Tang, Shangheng Liu, Chih‐Wen Pao, Zhiwei Hu, Qiaobao Zhang, Yong Xu, Hongbo Geng, Xiaoqing Huang
Abstract
H 2 O 2 photosynthesis has attracted great interest in harvesting and converting solar energy to chemical energy. Nevertheless, the high-efficiency process of H 2 O 2 photosynthesis is driven by the low H 2 O 2 productivity due to the recombination of photogenerated electron–hole pairs, especially in the absence of a sacrificial agent. In this work, we demonstrate that ultrathin ZnIn 2 S 4 nanosheets with S vacancies (S v -ZIS) can serve as highly efficient catalysts for H 2 O 2 photosynthesis via O 2 /H 2 O redox. Mechanism studies confirm that S v in ZIS can extend the lifetimes of photogenerated carriers and suppress their recombination, which triggers the O 2 reduction and H 2 O oxidation to H 2 O 2 through radical initiation. Theoretical calculations suggest that the formation of S v can strongly change the coordination structure of ZIS, modulating the adsorption abilities to intermediates and avoiding the overoxidation of H 2 O to O 2 during O 2 /H 2 O redox, synergistically promoting 2e – O 2 reduction and 2e – H 2 O oxidation for ultrahigh H 2 O 2 productivity. The optimal catalyst displays a H 2 O 2 productivity of 1706.4 μmol g –1 h –1 under visible-light irradiation without a sacrificial agent, which is ∼29 times higher than that of pristine ZIS (59.4 μmol g –1 h –1 ) and even much higher than those of reported photocatalysts. Impressively, the apparent quantum efficiency is up to 9.9% at 420 nm, and the solar-to-chemical conversion efficiency reaches ∼0.81%, significantly higher than the value for natural synthetic plants (∼0.10%). This work provides a facile strategy to separate the photogenerated electron–hole pairs of ZIS for H 2 O 2 photosynthesis, which may promote fundamental research on solar energy harvest and conversion.