Photocatalytic self-cleaning holey graphene oxide membranes by a synergistic strategy of etching and intercalation for efficient dye separation

Abstract

By virtue of the unique percolation mechanism, graphene oxide (GO)-based membrane has been broadly trialed in the field of dye separation. However, the trade-off between permeability and selectivity, together with membrane contamination, has long limited its practical application. Herein, a synergistic strategy of etching and intercalation was applied to fabricate a novel composite nanofiltration membrane. Holey graphene oxide (HGO) was prepared via a simple solution processing method, which generated in-plane nanopores on GO nanosheets, resulting in improved permeability. To enhance the selectivity of the composite membrane, we intercalated polydopamine (PDA)-modified graphitic phase carbon nitride (g-C₃N₄) into HGO laminates. During the process, a skillful combination of efficient dye separation performance, satisfactory chemical stability and superior self-cleaning property were given to it. What can be found intuitively was that M₂ membrane (g-C₃N₄@PDA: HGO = 0.75:1) obtained an impressive pure water flux (49.6 L m⁻² h⁻¹) and a good removal of various dyes (>99 %). The membrane structure was still intact after one month of continuous shaking in a harsh environment. Even after 60 h of operation (with visible light self-cleaning at 10 h intervals), the composite membrane still provided sustainable separation performance. Therefore, this collaborative strategy presents a facile and perspective approach for the fabrication of highly efficient GO-based membrane.