Surface indium vacancies promote photocatalytic H2O2 production over In2S3

Photocatalytic oxygen reduction reaction (ORR) represents a green and cost-effective means to produce the high-value industrial compound H 2 O 2 . However, the efficient H 2 O 2 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 In ) have been introduced into In 2 S 3 , which significantly boosts the photocatalytic activity for H 2 O 2 production, with an optimal H 2 O 2 generation rate of 4.77 ± 0.05 mmol·h −1 ·g cat. −1 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 In , such as enlarging the chemisorption capacity of O 2 , enriching photo-generated electrons for ORR, endorsing high reducing power to photo-generated electrons, and promoting H 2 O 2 desorption. These findings justify that surface cation vacancies open up new possibilities for H 2 O 2 photosynthesis by leveraging their reaction dimensions in ORR.