Photocatalytic H₂O₂ production over Ti(HPO₄)₂ S-scheme heterojunction through push-pull electronic effects enhance the oxygen reduction

This study focuses on enhancing the photocatalytic performance of Ti(HPO₄)₂ for H₂O₂ synthesis. Ti(HPO₄)₂, an intercalated structure photocatalyst with suitable band gap energy, has great potential in photocatalytic applications. However, its performance in H₂O₂ photosynthesis needs improvement in oxygen reduction kinetics and electron lifetime. We employed oxygen vacancy engineering to modulate the local oxygen environment of Ti(HPO₄)₂. This process reconstructs the Ti³⁺-O_v-P structures by leveraging push-pull electronic effects to increase the electron density at Ti⁴⁺ sites, thereby enhancing O₂ adsorption and activation. Moreover, we constructed an S-scheme heterojunction using WO₃ as a complementary oxidative cocatalyst. This heterojunction effectively suppressed carrier recombination and preserved the intrinsic redox abilities of each component. The optimized WO₃/TPO_v showed remarkable performance in a pure H₂O/O₂ system without sacrificial agents. It exhibited a 15-fold activity enhancement over pristine TPO and achieved an SCC efficiency of 0.75%. Our work offers a novel strategy of defect and heterojunction engineering for optimizing carrier lifetime and surface reactivity in photocatalytic systems.