Ultrafast Fabrication of Nanoporous, Atomically Thin Membranes Based on Wafer-Scale Graphene

Abstract

Membrane separation technologies are garnering significant attention in both industry and academia due to their potential for energy savings and operational effectiveness. Among the promising materials for membranes, wafer-scale single-crystal graphene emerges as an exceptional candidate due to its ultraflat surface, superior mechanical strength, and chemical stability, making it ideal for the top-down fabrication of nanoporous separation membranes. Despite these promising properties, the slow etch rate of copper and the low transfer efficiency of wafer-scale graphene membranes pose challenges to their large-scale application. In this work, we present an innovative method for the rapid fabrication of nanoporous atomically thin membranes (NATMs) using wafer-scale graphene. We utilized argon plasma to treat the graphene wafers. Subsequently, a nonsolvent-induced phase inversion process using poly(vinylidene fluoride) (PVDF) was employed to create a porous support layer on a large scale. By wetting the PVDF with ethanol before etching the copper, we not only facilitated accelerated etchant diffusion during copper etching, but also introduced size-selective defects that enhance the separation performance. Our approach increases the etch rate of copper by 115 times compared to conventional transfer methods while maintaining the selectivity of the NATMs. Remarkably, the entire fabrication process can be completed on a 4 in. wafer within 1 h. This novel transfer method represents a significant advancement in overcoming the challenges of efficient graphene transfer without sacrificing the separation properties of graphene, thereby bringing graphene-based films closer to practical, real-world applications.