Zn2In2S5/In2S3 S-scheme heterostructures for sacrificial-agent-free photocatalytic H2O2 production

Limited by rapid carrier recombination, the photocatalytic hydrogen peroxide (H 2 O 2 ) generation performance of Zn 2 In 2 S 5 is far from practical application. Herein, Zn 2 In 2 S 5 /In 2 S 3 S-scheme heterostructures were constructed by employing a one-step hydrothermal strategy that precisely adjusted the Zn:In precursor ratio. Thanks to the band structures with sufficiently redox ability of In 2 S 3 and Zn 2 In 2 S 5 , as well as enhanced carrier separation and transfer efficiency, the optimal Zn 2 In 2 S 5 /In 2 S 3 heterostructures (ZIS/In 2 S 3 -1:4) achieved a sacrificial-agent-free H 2 O 2 production rate of 339.5 μM h −1 under AM 1.5 irradiation, which approximately 1.7 times higher than that of pristine Zn 2 In 2 S 5 . Meanwhile, it also exhibited good H 2 O 2 evolution rate under visible-light irradiation and reusability. Its apparent quantum yield (AQY) at 380 nm, 420 nm, and 450 nm reached to 1.32 %, 1.11 %, and 0.63 %, respectively. In addition, the introduction of In 2 S 3 inhibited H 2 O 2 decomposition and enhanced the selectivity of H 2 O 2 production. In the photocatalytic process, superoxide radicals and holes were the key reactive substances, thereby H 2 O 2 was generated via a two-step single-electron O 2 reduction reaction process and one-step two-electron water oxidation reaction process. The construction strategy of the Zn 2 In 2 S 5 /In 2 S 3 S-scheme heterostructures is expected to provide a new perspective for the design of photocatalysts for efficient H 2 O 2 synthesis.