Femtosecond transient absorption spectroscopy investigation on ultrafast electron transfer in S-scheme ZnO/CdIn2S4 photocatalyst for H2O2 production and benzylamine oxidation

IF 10.8 2区化学 Q1 CHEMISTRY, PHYSICAL

物理化学学报 Pub Date : 2025-02-19 DOI:10.1016/j.actphy.2025.100064

Yi Yang , Xin Zhou , Miaoli Gu , Bei Cheng , Zhen Wu , Jianjun Zhang

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Abstract

Photocatalytic hydrogen peroxide (H₂O₂) production is a crucial process for clean energy conversion, involving the reduction of O₂ through two electrons. However, this process is often hampered by the sluggish water oxidation involving the photogenerated holes. To address this challenge, we have constructed a dual-functional S-scheme ZnO/CdIn₂S₄ heterojunction systerm coupling the H₂O₂ generation with a value-added benzylamine (BA) oxidation reaction. In this dual-functional photocatalytic system, photogenerated electrons in CdIn₂S₄ efficiently reduce O₂ to produce H₂O₂, while photogenerated holes in ZnO selectively oxidize BA to N-benzylidenebenzylamine. Leveraging the advantages of the S-scheme heterojunction, the optimized ZnO/CdIn₂S₄ photocatalyst displays an enhanced H₂O₂ production rate (386 μmol·L⁻¹·h⁻¹) and BA oxidation fraction (81 %) than pure ZnO or CdIn₂S₄. Femtosecond transient absorption (fs-TA) spectroscopy confirm the ultrafast S-scheme electron transfer from the ZnO conduction band (CB) to the CdIn₂S₄ valence band (VB) upon photoexcitation of the ZnO/CdIn₂S₄ composite. Besides, timely depletion of VB holes in ZnO and CB electrons in CdIn₂S₄ can accelerate the interfacial electron transfer in the ZnO/CdIn₂S₄ S-scheme heterojunction. The innovative design of the ZnO/CdIn₂S₄ S-scheme photocatalyst provides new insights for developing efficient dual-functional heterojunction photocatalytic systems and introduces a novel method for studying S-scheme heterojunctions using fs-TA spectroscopy.

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