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. The literature on gas separation using porous graphene membranes is based on complex methods that limit membrane size and reproducibility. Here we introduce several interventions that substantially 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 plays a crucial role in achieving uniform oxidation of large-area graphene. Crack formation during the transfer of graphene, which also limits reproducibility, is eliminated using a 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. Atom-thin graphene membranes for gas separation face scale-up challenges. The authors introduce scalable and reproducible approaches that simplify the fabrication of atom-thin porous graphene membranes, achieving membrane areas up to 50 cm2 with promising performance for point-source carbon capture.