Iso-Elemental ZnIn₂S₄/Zn₃In₂S₆ Heterojunction with Low Contact Energy Barrier Boosts Artificial Photosynthesis of Hydrogen Peroxide

Artificial photosynthesis emerges as a strategic pathway to produce hydrogen peroxide (H₂O₂), an environmentally benign oxidant and a clean energy carrier. Nonetheless, in many heterojunction-based artificial photosynthetic systems, the H₂O₂ productivity is significantly hindered by poor carrier transport, narrow spectral light absorption, and a lack of adequate active sites for the two-electron oxygen reduction reaction. Herein, a catalyst architecture with an iso-elemental heterojunction formed by interfacing Zn₃In₂S₆ nano-flowers and ZnIn₂S₄ nanosheets is proposed. This catalyst exhibits a H₂O₂ production rate as high as 23.47 µmol g⁻¹ min⁻¹ under UV–vis light irradiation, which is attributed to the minimized contact energy barrier and enhanced lattice match at the ZnIn₂S₄/Zn₃In₂S₆ interface thanks to the iso-elemental catalyst architecture which aids in enhanced efficient separation and transfer of photogenerated carriers. Theoretical simulations alongside comprehensive in-situ and ex-situ characterizations confirm the photo-redox sites for H₂O₂ generation and effective carrier dynamics across the catalyst surface. Moreover, substituting one reduction-type catalyst ZnIn₂S₄ with other non-iso-elemental catalysts like CdIn₂S₄, TiO₂, and CdS further confirms the feasibility and superiority of the proposed iso-elemental configuration. This work offers a new perspective on designing heterojunction catalysts for artificial photosynthesis of H₂O₂. © 2024 The Author(s). Advanced Energy Materials published by Wiley-VCH GmbH.