Interface photo-charge kinetics regulation by carbon dots for efficient hydrogen peroxide production

Hydrogen peroxide (H 2 O 2 ) is a multi-functional chemical for a range of industries, but the present H 2 O 2 production requires complex processes, and leads to environmental pollution, etc. Solar water-splitting is one of the potential avenues to combine H 2 O and O 2 into H 2 O 2 through a cheap and clean way. Most of the photocatalysts involve multiple components and interfaces to improve the catalytic activity and energy conversion efficiency. However, it is difficult to regulate the photo-charge kinetics between the multi-interface catalyst, which hinders the practical application of photocatalysts. Here, we report a SnS 2 /In 2 S 3 type II heterostructure modified by carbon dots (SnS 2 /In 2 S 3 /CDs) to highly improve the stability of sulfides and realize generation of H 2 O 2 by the oxygen reduction reaction (ORR). Notably, in situ transient photovoltage measurements (TPV) were carried out to analyze the charge transfer process among SnS 2 , In 2 S 3 and CDs. The optimal SnS 2 /In 2 S 3 /CD composite ( n (Sn): n (In) = 50%) displays a prominent H 2 O 2 production rate of 1111.89 μmol h −1 g −1 without any sacrificial agent under the conditions of normal pressure and neutral solution (pH = 7). The quantum efficiency (QE) of H 2 O 2 production was calculated to be 3.9% under light ( λ = 535 nm), and the solar energy conversion efficiency (SCC) was up to 1.02%, which is the highest known production of H 2 O 2 from sulfides as photocatalysts. Our work provides a new way to regulate the photo-charge kinetics of the multi-interface catalyst using CDs to achieve the extremely efficient production of H 2 O 2 by photocatalytic water-splitting. Interface photo-charge kinetics can be regulated by carbon dots for efficient hydrogen peroxide production.