Surface‐Modified Zn ₃ In ₂ S ₆ for a Dual‐Pathway Photocatalytic Hydrogen Peroxide Production

Photocatalytic H ₂ O ₂ production via a two‐electron oxygen reduction reaction (ORR) represents a green and sustainable alternative to the conventional anthraquinone process for industrial H ₂ O ₂ synthesis. Bimetallic sulfide Zn ₃ In ₂ S ₆ has emerged as a promising photocatalyst for H ₂ O ₂ production, yet the efficiency remains to be promoted. In this work, we introduced an anionic surfactant, sodium dodecyl sulfate (SDS), into the hydrothermal reactant to achieve a surface‐modified Zn ₃ In ₂ S ₆ with a high photocatalytic H ₂ O ₂ production efficiency. The SDS modification alters the electron state and band alignments and promotes the formation of sulfur vacancies. Consequently, the SDS modification tactic not only enhances charge separation and migration but also switches the reaction pathway from an ORR‐dominated route in the pristine Zn ₃ In ₂ S ₆ to a dual‐pathway involving both ORR and water oxidation reaction (WOR). The optimized SDS0.5‐Zn ₃ In ₂ S ₆ photocatalyst achieves a remarkable H ₂ O ₂ production rate of 1066.13 μmol·g ⁻¹ ·h ⁻¹ in pure water without any sacrificial agents, which is 1.6 times that of the pristine Zn ₃ In ₂ S ₆ . Moreover, under argon atmosphere, it exhibits a H ₂ O ₂ production rate of 598.83 μmol·g ⁻¹ ·h ⁻¹ , approximately three times that of unmodified Zn ₃ In ₂ S ₆ , confirming the enhanced WOR contribution. This work presents a novel Zn ₃ In ₂ S ₆ ‐based photocatalyst with dual reaction pathways for efficient photocatalytic H ₂ O ₂ production.