Construction of S-scheme heterojunction dual-path photocatalytic hydrogen peroxide synthesis by covalent organic...

Hydrogen peroxide (H₂O₂) 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 AgInS₂ quantum dots (AIS QDs) supported on a flower-like covalent organic framework (T-COF) was developed for H₂O₂ production. The optimized composite achieved an H₂O₂ production rate of 2768 μmol g^-1 h^-1, 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 H₂O₂ 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 H₂O₂ production performance.