Scalable synthesis of CO2-selective porous single-layer graphene membranes

Membranes based on atom-thin, porous single-layer graphene (PG) have shown attractive performance for diverse separation applications, especially gas separation and carbon capture. However, despite a decade of research, a scalable synthesis of PG membranes has remained under question. This is mainly because the literature resorts to complicated and expensive methods that yield small membranes and limited reproducibility. Herein, we introduce several interventions that significantly reduce PG membrane cost, allow uniform pore formation in a large area, and enable the preparation of large-area PG membranes with attractive performance. We show that mass transfer of the oxidant, neglected in the literature, plays a crucial role in achieving uniform oxidation of large-area graphene. Crack formation during the transfer of graphene, a major challenge in this field that also limits reproducibility, is eliminated using a novel protocol that does not require delicate floating and handling of graphene, allowing the realization of a high-performance 50 cm2 graphene membrane in a cross-flow module.