Strain‐Amplified Interfacial Electric Field in an S‐Scheme Cu‐TCPP/CdSe Heterojunction for Efficient Photocatalytic H ₂ O ₂ Production in Pure Water

Abstract Solar‐driven synthesis of hydrogen peroxide (H ₂ O ₂ ) from water and O ₂ represents a sustainable and cost‐effective alternative to conventional processes. However, the weak redox capacity and rapid carrier recombination in single‐component photocatalysts remain significant bottlenecks. Here, rational strain engineering coupled with internal electric field intensification strategy to enhance photocatalytic H ₂ O ₂ generation by constructing an S‐scheme heterojunction is reported. This is achieved via the in situ growth of CdSe nanowires, modulated by diethylenetriamine (DETA), on a copper‐porphyrin‐based metal–organic framework (Cu‐TCPP). The strained 3% Cu‐TCPP/CdSe‐DETA (3% Cu‐TCPP/CdSe‐D) demonstrates a substantial enhancement in photocatalytic H ₂ O ₂ production, reaching 2338.23 µmol g ⁻¹ h ⁻¹ under visible light, a 2.86‐fold enhancement over unmodified CdSe‐DETA. Comprehensive characterizations, including extended X‐ray absorption fine structure (EXAFS), in situ X‐ray photoelectron spectroscopy (ISIXPS), and femtosecond transient absorption (fs‐TA) spectroscopy, reveal that tensile strain and heterojunction formation synergistically promote interfacial charge separation and accumulation. Density functional theory (DFT) calculations further show that strain modulation intensifies the built‐in electric field and redistributes electrons toward catalytic sites, weakening the O─O bond and facilitating oxygen activation. This work presents a robust platform for designing strain‐engineered S‐scheme heterojunctions to unlock high‐performance photocatalytic H ₂ O ₂ production under ambient conditions.