Compressive interatomic distance stimulates photocatalytic oxygen-oxygen coupling to hydrogen peroxide

Photocatalytic hydrogen peroxide (H₂O₂) generation is largely subject to the sluggish conversion kinetics of the superoxide radical (O₂^⋅-) intermediate, which has relatively low reactivity and requires high energy. Here, we present a lattice-strain strategy to accelerate the conversion of O₂^⋅- to highly active singlet oxygen(¹O₂) by optimizing the distance between two adjacent active sites, thereby stimulating H₂O₂ generation via low-barrier oxygen-oxygen coupling. As the initial demonstration, the defect-induced strain in ZnIn₂S₄ nanosheet optimizes the distance of two adjacent Zn sites from 3.85 to 3.56 Å, resulting in that ZnIn₂S₄ with 0.7% compressive strain affords 3086.00 μmol g^-1 h^-1 yield of H₂O₂ with sacrificial agent. This performance is attributed to the strain-induced enhancement of electron coupling between the compressed adjacent Zn sites, which promotes low-barrier oxygen-oxygen coupling to active ¹O₂ intermediate. This finding paves the way for atomic-scale manipulation of reactive sites, offering a promising approach for efficient H₂O₂ photosynthesis.