Study on Photochemical Properties of a Sr-SnS₂/CaIn₂S₄ Heterostructure to Improve Cr(VI) Removal

Abstract

Compound semiconductor photocatalysis technology is considered to be a promising treatment for solving water problems efficiently. The point of designing high-efficiency catalysts is to optimize the band gap structure and facilitate the separation of charge carriers by establishing new electron migration pathways. Recently, 3D porous CaIn2S4 was found to have good photocatalytic ability. However, the quick recombination and agglomeration of carriers still limit its application. Herein, we prepared a heterostructure by introducing 2D Sr-doped SnS2 to 3D CaIn2S4 by a hydrothermal synthesis method. The optimal dosage of Sr-SnS2 is 3%, and the photocatalytic Cr­(VI) removal efficiency of 3% Sr-SnS2/CaIn2S4 (SSCS-3) is 5.82 and 10.83 times those of pure CaIn2S4 and SnS2, respectively. According to the results of characterization tests and calculation verification, we inferred that the enhanced photocatalytic removal of Cr­(VI) is due to the introduction of Sr-SnS2 that can promote the rapid transfer of photogenerated electrons to the surface of CaIn2S4, and the heterostructure formed between 2D Sr-SnS2 and 3D CaIn2S4 can also provide abundant reaction sites. The promotion of carrier separation is mainly due to the formation of a built-in electric field of the Sr-SnS2/CaIn2S4 heterostructure. This work provides new ideas and technologies for the treatment of Cr­(VI) in wastewater.

Synthesis and Photocatalytic Application of Magnetic CoFe2O4/Conjugated Poly(vinyl chloride) Derivative Nanocomposite

“…Among the several approaches developed for the reduction of Cr(VI), photocatalytic reduction possesses unparalleled strengths, such as directly utilizing sunlight as the energy for activating the redox reactions, effectively preventing secondary pollution, and greatly reducing the cost. − As a consequence, photocatalytic reduction would be a more sustainable advanced approach for treating Cr(VI) in waterbodies for the time to come. But, the practical industrial application of photocatalytic reduction approach has still not been realized so far, mainly due to the lack of high performance and easily recycled visible-light photocatalysts. − Nearly all of the synthetic photocatalysts show some intrinsic weaknesses, for instance, insufficient visible-light photocatalytic activity, considerable difficulty in being separated from water, dissatisfactory stability, or unacceptable expensiveness. Thus, there is an increasing demand for producing new visible-light photocatalysts that are highly efficient, easy to recover, stable, and cost-effective.…”