Noble metal-free MoS2-modified In2S3 for excellent visible-NIR-light-driven photocatalytic of Cr6+ removal in alkaline wastewater

Abstract

MoS2-modified In2S3 (x wt.%MoS2-In2S3) samples (0 ≤ x ≤ 20) were fabricated through a facile one-pot hydrothermal process. All In2S3 samples modified by MoS2 deliver an excellent Cr6+ removal ability under visible-NIR-light-driven, and 5% MoS2-In2S3 can reduce 20 mg/L Cr6+ solution completely within 30 min with a trace photocatalyst concentration (0.27 mg/mL) which is 3.2-hold higher than that of single In2S3. Further investigations demonstrate that the loaded MoS2 can not only enhance the absorption of light scope but also promote the interfacial electron transfer from In2S3 to MoS2 and then to Cr6+, thus greatly improving the Cr6+ removal ability. ESR shows that the modifying of MoS2 can accelerate the transformation of electrons from the In2S3 to MoS2 which results in that the intensity of O2−• significantly increased. PL, photocurrent, and EIS further identified that the modification of MoS2 can greatly improve the charge carrier separation efficiency. The fabricated MoS2-In2S3 samples also exhibit characteristic features such as stable and reducing Cr6+ in the weak alkaline environment for the first time, which could always be a great challenge for wastewater purification in alkaline condition.