Gentle Gradient-Reduction of Graphene Oxide Membranes by Interfacial Redox Reaction toward Breaking Selectivity-Permeability Trade-off

Graphene oxide membranes hold promising application potential in molecular nanofiltration, but the traditional selectivity-permeability trade-off is still a challenge. Here, an interfacial redox reaction strategy based on poly(m-phenylenediamine)-graphene oxide (PmPD-GO) interaction was successfully designed to achieve the fabrication of an ultrathin graphene oxide membrane (∼28 nm) with a reasonable reduction state (C/O ratio of 11.2) and adequate interlayer spacing stabilized at 8 ± 0.5 Å, which supplies not only a favorable microenvironment for fast water transport but also a suitable interlayer distance for molecules gating. The resultant membrane exhibits a high permeance of 72 LMH/bar and an exceptional dye rejection rate exceeding 98%. Moreover, the gentle gradient-reduced graphene oxide membrane has significantly improved stability under long-term immersion, pH tolerance, and ultrasonic treatment tests. This research provided a simple and effective strategy for fabricating two-dimensional lamellar membranes with promising prospects for practical nanofiltration applications.