Modulating charge dynamics of Cu-CdSe-diethylenetriamine/APF S-scheme heterojunction via strain engineering for enhanced photocatalytic H₂O₂ production

Solar-driven photocatalytic synthesis of hydrogen peroxide (H₂O₂) represents a highly promising green chemistry route, yet its efficiency is severely constrained by the rapid recombination of photogenerated carriers in traditional photocatalysts. In this study, a Cu doped CdSe-diethylenetriamine/benzoxazine-based 3-aminophenol-formaldehyde (Cu-CdSe-D/APF) photocatalyst integrating strain modulation effects and S-scheme heterojunction characteristics was successfully constructed via a Cu²⁺ modification strategy. Photocatalytic performance tests revealed that the as-synthesized 0.7%Cu-CdSe-D/APF exhibited superior H₂O₂ evolution activity under visible light irradiation (λ ≥ 420 nm), achieving a yield of up to 5324.2 μmol g⁻¹ h⁻¹, which is 5.3 times higher than that of pristine CdSe-D. Combined analyses using geometric phase analysis, high-resolution transmission electron microscopy, and density functional theory calculations confirmed that the introduction of Cu²⁺ induces a non-uniform compressive strain field within the 0.7%Cu-CdSe-D/APF. This strain field acts synergistically with the built-in electric field at the S-scheme heterojunction interface, which not only significantly suppresses the recombination of photogenerated electron-hole pairs but also accelerates the directional migration of carriers and the kinetics of surface catalytic reactions. This study provides a new paradigm for designing highly efficient photocatalysts for H₂O₂ synthesis through a “strain engineering-heterojunction construction” synergistic strategy.