Rapid photocatalytic reduction of Cr(VI) with high concentration in wastewater by In2S3-ZnIn2S4 heterostructure hierarchical microtubes under visible light

Currently, Cr(VI) poses a great threat to the human health and ecosystem due to its acute toxicity and potential carcinogenicity. In order to quickly and efficiently reduce Cr(VI) to Cr(III) by photocatalysis, a new In2S3-ZnIn2S4 heterostructure hierarchical microtubes, which is based on the combination of the main three strategies for the enhancement of photocatalysts' performance including semiconductor heterostructure, hierarchical microstructure, and hollow morphology, were designed and successfully synthesized via a facile liquid chemical treatment of metal-organic frameworks pre-synthesized as a self-sacrificing template. The microstructure, composition and photocatalytic properties of In2S3-ZnIn2S4 composite were investigated by means of SEM, TEM, XRD, XPS, PL and electrochemical techniques. The photocatalytic reduction performance of In2S3-ZnIn2S4 composites are much better than that of pure In2S3 and ZnIn2S4 under visible light irradiation. For the best photocatalytic activity of the as-prepared sample, the Cr(VI) with the initial concentration of 80 ​mg/L in the water can be photocatalytic reduced 93.4% in 10 ​min under visible light irradiation, which meet the requirement of design well.