Scalable fabrication of nanoporous multilayer graphene oxide membrane for organic solvent nanofiltration

Nanoporous graphene is promising for the fabrication of high-performance organic solvent nanofiltration (OSN) membranes owing to the excellent chemical resistance of graphene in organic solvents. Moreover, the nanopores increase solvent permeance by providing diffusion channels. However, conventional chemical and physical etching methods are generally applicable on a laboratory-scale, and the large-scale fabrication of these structures is challenging. Herein, a large-area nanoporous multilayer graphene oxide (NMG) membrane was prepared using a combination of slot-die coating and confined thermal treatment. Graphene oxide (GO) was coated on polymeric supports using a slot-die coater, which is generally used for continuous coating in industry. Afterward, the GO membrane was treated using a hot-pressing method to activate the nanopores on the graphene surface and weld the polymeric support with the graphene layer. The interlayer and pore structure of GO were tuned by modu-lating the hot-pressing time, and its influence on OSN performance was systemically investigated. The optimized NMG membrane exhibited a high ethanol permeance of 300 Lm- 2h-1bar- 1 and a sharp molecular weight cut-off of 500 g/mol. Furthermore, the enhanced adhesion between graphene and the polymeric support enables me-chanically stable membrane operation under cross-flow conditions for 30 days, which is the longest test time reported for two-dimensional material-based OSN membranes thus far.