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

Hydrogen peroxide (H2O2) is a multi-functional chemical for a range of industries, but the present H2O2 production requires complex processes, and leads to environmental pollution, etc. Solar water-splitting is one of the potential avenues to combine H2O and O-2 into H2O2 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 SnS2/In2S3 type II heterostructure modified by carbon dots (SnS2/In2S3/CDs) to highly improve the stability of sulfides and realize generation of H2O2 by the oxygen reduction reaction (ORR). Notably, in situ transient photovoltage measurements (TPV) were carried out to analyze the charge transfer process among SnS2, In2S3 and CDs. The optimal SnS2/In2S3/CD composite (n(Sn):n(In) = 50%) displays a prominent H2O2 production rate of 1111.89 mu mol h(-1) g(-1) without any sacrificial agent under the conditions of normal pressure and neutral solution (pH = 7). The quantum efficiency (QE) of H2O2 production was calculated to be 3.9% under light (lambda = 535 nm), and the solar energy conversion efficiency (SCC) was up to 1.02%, which is the highest known production of H2O2 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 H2O2 by photocatalytic water-splitting.