Cu-modified ZnO/COF S-scheme heterojunction for boosting H2O2 photosynthesis via the synergy of enhanced internal electric field and polarized field

The development of highly active photocatalysts for H₂O₂ production is of significant practical importance for addressing environmental issues and energy shortages. In this study, an S-scheme heterojunction photocatalyst with strong redox performance was synthesized through the in-situ growth of the TpPa-Cl covalent organic framework (COF) material on the surface of Cu-loaded ZnO nanorods. The incorporation of Cu disrupts the charge shielding effect of ZnO, promotes the spatial separation of charge carriers, and enhances piezoelectric catalytic activity. Furthermore, the porous ultra-thin COF layer extends carrier lifetime and increases the contact area with reactants, endowing the composite with strong light absorption capacity and excellent oxygen reduction performance. Under the combined influence of the piezoelectric-photocatalytic dual electric field, the H₂O₂ yield of the composite in pure water reached 1838.8 μmol g⁻¹ h⁻¹, and the resulting H₂O₂ solution can be directly utilized for pollutant removal and water disinfection. In situ X-ray photoelectron spectroscopy, density functional theory calculations, and electron spin resonance studies elucidate the S-scheme electron transfer mechanism, which accelerates the transfer of photogenerated carriers and enhances the utilization of electron-hole pairs. This research offers a novel approach for the design and development of catalysts aimed at efficient H₂O₂ production.