Construction of S-scheme heterojunction dual-path photocatalytic hydrogen peroxide synthesis by covalent organic frameworks loaded with AgInS(2) quantum dots.

Hydrogen peroxide (HO) is an important inorganic compound widely employed in chemical, industrial, medical, and environmental applications owing to its mild oxidation behavior, favorable reaction conditions, and environmentally benign decomposition products. In this study, a step-scheme(S-scheme) heterojunction photocatalyst composed of AgInS quantum dots (AIS QDs) supported on a flower-like covalent organic framework (T-COF) was developed for HO production. The optimized composite achieved an HO production rate of 2768 μmol g h, which is 5.5 and 2.1 times higher than that of pristine AIS QDs and T-COF, respectively, without the addition of any sacrificial agent. The reaction pathway of HO formation was elucidated through radical trapping experiments and in situ diffuse reflectance Fourier transform infrared spectroscopy. Femtosecond transient absorption spectroscopy (fs-TAS), theoretical calculations (DFT), in-situ kelvin probe force microscopy (KPFM) and in-suit X-ray photoelectron spectroscopy (in-suit XPS) collectively confirmed the efficient charge carrier transfer mediated by the S-scheme heterojunction. The formation of S-scheme heterojunctions effectively promotes charge carrier separation and enhances redox capability, leading to superior photocatalytic performance. This work paves a new avenue for the construction of 0D/2D inorganic/organic heterojunctions with efficient photocatalytic HO production performance.