Efficient Photocatalytic Reduction of Hexavalent Chromium by NiCo2S4/BiOBr Heterogeneous Photocatalysts

For typical Cr(VI)-containing industrial wastewater, more efficient water treatment technologies need to be used to ensure that Cr(VI) concentrations are reduced to safe levels before discharge. Photocatalytic technology is highly efficient, environmentally friendly, and has been extensively used to address this demand. Herein, heterogeneous NiCo2S4/BiOBr photocatalysts with different ratios were prepared using a solvothermal method. When compared with pure NiCo2S4 and BiOBr, the NiCo2S4/BiOBr-30 had significantly increased adsorption capacity and visible-light-driven photocatalytic reduction activity for Cr(VI) removal. The improved adsorption performance of the NiCo2S4/BiOBr-30 was mainly due to its increased specific surface area, and the enhanced photocatalytic performance of the NiCo2S4/BiOBr-30 could be attributed to the improved separation and transfer of photogenerated carriers at the interface. Lastly, a possible enhanced photocatalytic Cr(VI) reduction mechanism of the NiCo2S4/BiOBr heterostructure was developed.