Enhancement of Sulfur Source-Dependent Zn Vacancies in Different Photocatalytic Performances of ZnIn2S4 Nanoparticles

This study focuses on the synthesis and investigation of ZnIn₂S₄ nanoparticle (NP) photocatalysts treated with different sulfur sources, thioacetamide (TAA), or thiourea (TU), to explore their wavelength-dependent photocatalytic activity. The research aims to understand the impact of Zn vacancies present on the surface of ZnIn₂S₄ NPs. The investigation involves electron spin resonance and in situ X-ray photoelectron spectroscopy to study the photocatalytic activity of ZnIn₂S₄-TU and ZnIn₂S₄-TAA NPs, following the characterization of surface morphology and electronic properties using high-resolution transmission electron microscopy and X-ray diffraction. Additionally, the study delves into the wavelength-dependent photocatalytic degradation (PCD) activity of the ZnIn₂S₄ NPs using 2,5-hydroxymethylfurfural (HMF) across a wide range. Notably, the selective oxidation of HMF using ZnIn₂S₄-TU NPs resulted in the formation of 2,5-furandicarboxylic acid (FDCA) via 2,5-diformylfuran, with an efficiency exceeding 40% over the broad wavelength range. The research demonstrates that the irradiation wavelength for PCD is influenced by the number of defect structures introduced into the ZnIn₂S₄ NPs through the sulfur source.