S-scheme Zn2In2S5/CdS nanosheet-on-nanosheet heterostructures with tight interfacial contacts promote efficient H2O2 photoproduction from pure water

Abstract

Photocatalytic hydrogen peroxide (H₂O₂) production from pure water emerges as an innovative green strategy, utilizing sunlight and water to produce a valuable chemical in an environmentally benign manner. In this study, Zn₂In₂S₅/CdS (ZnInS/CdS) nanosheet-on-nanosheet S-scheme heterostructures with intimate interfacial contact were constructed via in situ growth of ZnInS on CdS. The resulting ZnInS/CdS heterostructures significantly enhance photocatalytic H₂O₂ generation through a two-step single-electron oxygen reduction reaction (ORR). The optimized 3ZnInS/CdS sample achieved a remarkable H₂O₂ yield of 185.28 ± 5.79 µM under visible light irradiation for 1 h, which is approximately 11.68 and 4.71 times higher than those of pure ZnInS and bare CdS, respectively. Moreover, the 3ZnInS/CdS heterostructure exhibits a stable crystal structure and excellent recyclability. Based on comprehensive evidence from in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), electron paramagnetic resonance (EPR), and density functional theory (DFT) calculations, an S-scheme charge transfer mechanism is proposed for the ZnInS/CdS heterostructures. This study offers a promising strategy for designing highly efficient hybrid systems for visible-light-driven H₂O₂ synthesis from pure water.