Surface indium vacancies promote photocatalytic H<sub>2</sub>O<sub>2</sub> production over In<sub>2</sub>S<sub>3</sub>.

Zhu, Qiong; Su, Jingjing; Lin, Guoan; Li, Guisheng; Zhuo, Zhiwen; Wang, Weiyi; Li, Jialin; Xu, Xiaoxiang · Nat Commun · 2025

basic_science · Level V

Where this comes from

Abstract

Photocatalytic oxygen reduction reaction (ORR) represents a green and cost-effective means to produce the high-value industrial compound H<sub>2</sub>O<sub>2</sub>. However, the efficient H<sub>2</sub>O<sub>2</sub> synthesis awaits in-depth knowledge of the ORR mechanisms for the design of highly active photocatalysts. In this work, surface indium vacancies (denote hereafter as V<sub>In</sub>) have been introduced into In<sub>2</sub>S<sub>3</sub>, which significantly boosts the photocatalytic activity for H<sub>2</sub>O<sub>2</sub> production, with an optimal H<sub>2</sub>O<sub>2</sub> generation rate of 4.77 ± 0.05 mmol·h<sup>-1</sup>·g<sub>cat.</sub><sup>-1</sup> under visible light illumination (λ ≥ 420 nm) and an apparent quantum efficiency (AQE) of 7.49 ± 0.01% at 420 ± 20 nm. Mechanistic analysis reveals the multifunctionality of V<sub>In</sub>, such as enlarging the chemisorption capacity of O<sub>2</sub>, enriching photo-generated electrons for ORR, endorsing high reducing power to photo-generated electrons, and promoting H<sub>2</sub>O<sub>2</sub> desorption. These findings justify that surface cation vacancies open up new possibilities for H<sub>2</sub>O<sub>2</sub> photosynthesis by leveraging their reaction dimensions in ORR.