Precise Regulation of Zn, S Dual Vacancies in Zn 3 In 2 S 6 Inducing Local Orientated Electrical Field for Photocatalytic H 2 O 2 Generation

Photocatalytic H2O2 synthesis attracts interest for solar-to-fuel conversion but suffers from low carrier utilization and sluggish kinetics. Herein, we present a confinement strategy to precisely regulate Zn and S vacancies (VZn, VS) in Zn3In2S6 for photocatalytic H2O2 generation. ZnSO4, InCl3, thioacetamide, and cetyltrimethylammonium bromide (CTAB) were utilized to synthesize Zn3In2S6 via a hydrothermal process, in which CTAB inserts into anionic layers and forms covalent bonds with Zn2+ ions, then pyrolyzes and removes Zn2+ ions during the annealing process, inducing VZn formation. H2-mediated desulfurization generates VS. The contents of VZn and VS in Zn3In2S6 of 1.9:1.0, 1.1:1.0, 1.0:1.9, and 1.0:3.3 were obtained by adjusting the temperature. VS&VZn-Zn3In2S6 (1.0:1.9) exhibits a fantastic photocatalytic generation rate of 11580.74 µmol g-1 h-1 for H2O2 which increased 2.4 times compared with VS-Zn3In2S6, attributing to that dual vacancies promote the local orientated electrical field (LOEF) formation and increase photogenerated-electron transfer from VS to VZn. Electrons delocalize onto adjacent Zn sites, promoting the two-electron oxygen reduction reaction (ORR) pathway. Simultaneously, VZn facilitates the migration of h⁺ to the catalyst surface, thereby increasing h⁺ utilization efficiency and accelerating the water oxidation reaction (WOR) process toward H2O2 production. VS&VCu-CuIn2S4 and VS&VNi-NiIn2S4 were successfully synthesized, highlighting its broad applicability as a general approach.