Nanoflower Bimetal CuInOS Oxysulfide Catalyst for the Reduction of Cr(VI) in the Dark

Bimetal CuInOS oxysulfide solid-solution catalysts were successfully synthesized by a feasible method. The reduction performance of CuInOS was investigated by the reduction of Cr(VI) aqueous solution in the dark without the light illumination and additional reagents. The results showed that CuInOS catalyst exhibited excellent reduction activity, with which the 100 mL Cr(VI) solution of 50 mg/L was completely reduced by 20 mg catalyst within 4 min. The CuInOS also performed relatively good stability and durability for the reusability tests of Cr(VI) reduction, in which 91.8% reduction was achieved in 4 min even after the sixth run. The end product of the Cr(VI) reduction was identified to be metallic Cr(0) with Cr3+ as an intermediate. CuInOS with extremely fast Cr(VI) reduction in the dark was well characterized for its bond and crystal structure, microstructure, composition, and physical properties. A reasonable Cr(VI) reduction mechanism was proposed. At last, CuInOS is recyclable and can be easily separated from solution due to its easy sedimentation.