Sulfur-defect-rich Bi₂S₃/ZnIn₂S₄ Z-scheme heterojunction for highly efficient H₂O₂ photosynthesis in pure water

Photocatalytic conversion of O₂ and H₂O provides a green and low-cost approach for the synthesis of H₂O₂, however, most of reaction systems involve sacrificial agents and the efficient photosynthesis of H₂O₂ in pure water remains a challenge. In this work, a Z-scheme Bi₂S₃/ZnIn₂S₄ heterojunction with rich sulfur defects was prepared by a one-step hydrothermal method. The combination of Bi₂S₃ with ZnIn₂S₄ greatly enhanced the absorption of visible light. The intimate heterojunction interface bonded through sulfur bridge efficiently promoted the separation and migration of photogenerated carriers. Moreover, the enlarged specific surface area, the existence of sulfur defects and the increase of surface hydrophobicity facilitated the oxygen reduction reaction. As a result, the H₂O₂ production rate of the Bi₂S₃/ZnIn₂S₄ heterojunction in pure water under visible light reached 1634 μmol g^-1 h^-1, which was 5.3 and 43.0 times those of ZnIn₂S₄ and Bi₂S₃, respectively. This work provides new ideas for the construction of novel heterojunction photocatalysts for H₂O₂ production.