Filter prepared from Janus-like graphene oxide nanosheets with heterogeneous nanochannels for highly efficient dye removal

Abstract

Filters assembled with graphene oxide (GO) nanosheets featuring uniform nanochannels exhibit excellent performance for molecular separation and hold great potential for water purification. However, the long and curved nanochannels constructed by highly ordered packing of conventional GO nanosheets seriously reduce the water permeability. Herein, a filter with heterogeneous nanochannels was prepared using Janus-like graphene oxide (JGO) via vacuum-assisted filtration and achieved high permeability without sacrificing the rejection rate. The JGO sheet possesses a special chemical structure with oxidized areas along the faces of the sheet, resulting in different interface properties for both sides of the JGO sheet. Therefore, the JGO filter fabricated by the vacuum-assisted self-assembly possesses both larger pores and smaller channels compared to common GO filters, providing higher permeability and rejection rates. The removal efficiency of the JGO-based filter towards various dye molecules exceeds 99%, and the permeability is maintained between 110 and 140 L m⁻² h⁻¹ bar⁻¹, which is more than three times that of the GO filter. This study demonstrates that the filters fabricated with Janus-like nanosheets exhibit both high separation efficiency and high permeability, showing promising application for water treatment.