Construction of hollow In2S3/CdIn2S4 heterostructures with high efficiency for Cr(vi) reduction

Abstract

Hexavalent chromium (Cr(VI)) poses a serious threat to the environment and human health due to its high-toxicity and carcinogenicity. For efficient removal of Cr(VI), semiconductor photocatalytic reduction methods have been investigated, especially those using hollow structures. In this work, a hollow In₂S₃/CdIn₂S₄ composite photocatalyst was prepared via ion exchange for the reduction of Cr(VI). The microstructure, composition, optical properties, and elements of the In₂S₃/CdIn₂S₄ composites were characterized via scanning electron microscopy, X-ray diffraction, UV-vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. Because of the molecular level heterojunction constructed through ion exchange and the hollow structure, the prepared photocatalyst demonstrated excellent catalytic properties for Cr(VI) reduction. Besides, a Cr(VI) aqueous solution (50 mg L⁻¹) was reduced within 12 min. Importantly, the activity and structure of the photocatalyst were maintained after five cycling experiments, which demonstrates its advantageous stability. Finally, the photocatalytic mechanism is discussed in detail.