Enhanced photocatalytic self-cleaning properties of GO membrane with fabrication of hierarchical tin sulfide/bismuth tungstate p-n heterojunction with 2D interfacial coupling for efficient separation of dyes

Graphene oxide (GO)-based membranes have been widely used in the field of wastewater treatment by virtue of their unique separation mechanism, but their practical applications are severely constrained by the problems of selectivity, permeability and membrane contamination. In this study, a novel nanofiltration membrane structure was innovatively designed using a dual strategy of cross-linking and intercalation, with a view to enhancing the membrane separation performance and service life. Modification of GO nanosheets with PEI molecules (polyethyleneimine) at room temperature improved the hydrophilicity of the nanosheets and resulted in a hydrophilic membrane surface and smooth interlayer channels. A novel flower-like type 2 %SnS 2 /Bi 2 WO 6 p-n heterojunction synthesized via hydrothermal and ultrasonic-thermal treatment techniques was embedded in a composite membrane, and the M2 membrane with the best performance was prepared (2 %SnS 2 /Bi 2 WO 6 : PEI@GO = 0.6: 1). The M2 membrane has 12 times (120.9 L m −2 h −1 ) the pure water flux of the GO membrane and retains more than 99 % of the MB molecules. Owing to the stabilization of the membrane structure by chemical crosslinking, after up to 130 h of cycling experiments (photocatalytic cleaning of the membrane surface was performed every 10 h.), the rejection rate of MB was still higher than 98 %. Therefore, for the preparation of high-performance GO-based membranes, this synergistic strategy provides a simple and effective method.