Facile Synthesis of a Z‑Scheme ZnIn₂S₄/MoO₃ Heterojunction with Enhanced Photocatalytic\nActivity under Visible Light Irradiation

Abstract

Employing a visible-light-driven\ndirect Z-scheme photocatalytic\nsystem for the abatement of organic pollutants has become the key\nscientific approach in the area of photocatalysis. In this study,\na highly efficient Z-scheme ZnIn₂S₄/MoO₃ heterojunction was prepared through the hydrothermal method,\nfollowed by the impregnation technique that facilitates the formation\nof an interface between the two phases for efficient photocatalysis.\nThe structural, optical, and surface\nelemental composition and morphology of the prepared samples were\ncharacterized in detail through X-ray diffraction, UV–vis diffuse\nreflectance spectra, X-ray photoelectron spectroscopy, scanning electron\nmicroscopy, and transmission electron microscopy. The results indicate\nthat the composite materials have a strong intimate contact between\nthe two phases, which is beneficial for the effective separation of\nphotoinduced charge carriers. The visible-light-mediated photocatalytic\nactivity of the samples was tested by studying the degradation of\nmethyl orange (MO), rhodamine B (RhB), and paracetamol in aqueous\nsuspension. An optimum loading content of 40 wt % ZnIn₂S₄/MoO₃ exhibits the best degradation efficiency\ntoward the above pollutants compared to bare MoO₃ and ZnIn₂S₄. The improved photocatalytic activity could\nbe ascribed to the efficient light-harvesting property and prolonged\ncharge separation ability of the Z-scheme ZnIn₂S₄/MoO₃ catalyst. Based on reactive species determination\nresults, the Z-scheme charge transfer mechanism of ZnIn₂S₄/MoO₃ was discussed and proposed. This study\npaves the way toward the development of highly efficient direct Z-scheme\nstructures for a multitude of applications.