Visible-light induced CoMoO4@Bi2MoO6 heterojunction membrane with attractive photocatalytic property and high precision separation toward oil-in-water emulsion

The discharge of wastewater containing insoluble oils and water-soluble organic pollutants has caused severe water pollution and seriously threatened the sustainable development of human society. Membrane separation technology, on the basis of the size sieving and superwettability, can effectively remove insoluble oils from the wastewater, but still lacking the ability to degrade water-soluble pollutants. Herein, a novel heterojunction membrane with dual functionalities of superhydrophilicity and visible-light photocatalytic property was prepared by constructing hierarchical CoMoO4@Bi2MoO6 nanoarrays on Ni foam (NF@CM@BM) via a facile twostep hydrothermal process combined with calcination methods. Attributed to the synergistic application of photocatalysis, superhyophilicity and underwater superoleophobicity, the membrane could simultaneously remove water-soluble organic pollutants and insoluble oils in wastewater efficiently. Completely driven by gravity, high oil/water separation efficiency of 99.67% could be achieved with the flux of 1449.12 L m(-2) h(-1). Besides, the formation of p-n heterojunction between p-type CoMoO4 and n-type Bi2MoO6 greatly enhanced the photocatalytic ability to degrade Congo red with the efficiency of 97.1%. More importantly, the NF@CM@BM membrane exhibited excellent stability and recyclability, possessing great application potential in oily wastewater remediation. Therefore, we envision that this work will offer new insights into the design of wastewater remediation membranes.