2D/3D BiVO₄@ZnIn₂S₄ Hierarchical Heterojunction for Enhanced One-Electron Oxygen Reduction Kinetics of H₂O₂ Artificial Photosynthesis

Hydrogen peroxide (H₂O₂) artificial photosynthesis converts low-density solar energy into storable clean chemical energy, which is an important hot topic in green chemistry. Constructing heterojunctions is an effective tactic to enhance the oxygen reduction kinetics of H₂O₂ photosynthesis, however, the actual source of activity remains ambiguous. Here, a series of BiVO₄@ZnIn₂S₄ hierarchical heterojunctions (BZ-<i>x</i>, <i>x</i> = 0.4, 0.8, 1.2) were elegantly designed through piecing two-dimensional (2D) BiVO₄ nanosheets onto the surface of three-dimensional (3D) ZnIn₂S₄ flower-like microspheres by a straightforward ethanol ultrasound-induced self-assembly strategy. These BZ-<i>x</i> photocatalysts exhibit significantly enhanced photocatalytic H₂O₂ production rates across a wide pH range (3-13) compared with those of pristine BiVO₄ and ZnIn₂S₄, with the optimal BZ-0.8 showing an excellent photocatalytic H₂O₂ production rate as high as 1585.99 μmol g^-1 h^-1. Comprehensive analysis reveals that 2D BiVO₄ nanosheets and 3D ZnIn₂S₄ flower-like microspheres form a Z-scheme hierarchical heterojunction, which can deliver a favorable energy coupling between photogenerated electrons and the chemical adsorption of O₂ at the interface of hierarchical heterojunctions, thereby accelerating the two-step one-electron kinetic process. This study provides a new perspective for improving photocatalytic H₂O₂ production by introducing hierarchical heterojunction strategies.