Visible-light photoreduction of Cr(VI) over CdIn2S4/MOF-808 composites

Although solar-light driven photocatalysis is a promising route to reduce Cr(VI) from wastewater, its challenge is to construct highly efficient and muti-functional photocatalysts. Herein, CdIn2S4 combined with MOF-808 (CIS/MOF-808) composites were prepared for boosting solar-light induced photoreduction of Cr(VI). The close contact between MOF-808 and CdIn2S4 was favorable for the separation and transfer of electron-hole pairs, and provided sufficient vacant sites of Cr(VI) adsorption and photon capture. The removal activity of Cr(VI) over CIS/MOF-808 hybrids was higher than pristine MOF-808 and CdIn2S4. CdIn2S4 content, pH, and inorganic salts affected the removal efficiency of Cr(VI) and the concentration of Cr3+ in aqueous solution. The removal efficiency of Cr(VI) over 4-CIS/MOF with a nominal CdIn2S4 content of 16 wt.% was 95.45%, and declined to 88.17% after five cycles. The acidic medium induced to the fast reaction between Cr(VI) and e− to form Cr(III), while deteriorated the metal leaching as well as photo-corrosion to restrain the photocatalytic activity.