Scaling-up CO2-selective graphene oxide membranes via sequential coating with gelated graphene oxide and polyethyleneimine for CO2 separation†

In our ongoing efforts to mitigate the rapidly increasing carbon dioxide (CO₂) emission, graphene oxide (GO) membranes are expected to be the next generation of CO₂ separation membranes. However, existing fabrication methods lack the scalability required for commercial production of laminar GO membranes. To address this challenge, we developed a scaled-up laminar GO membrane by coating a thin laminar GO film onto a commercial ultrafiltration membrane using a blade-casting technique in combination with an ion-crosslinked GO hydrogel. The as-prepared GO membrane was then surface-modified with polyethyleneimine to imbue a unique CO₂-selectivity for handling humidified CO₂-containing feed gases. Resultantly, this approach yielded a GO-based membrane with a scaled-up surface area of close to 0.1 m². The membrane demonstrated good uniformity and performances at CO₂/CH₄ and CO₂/N₂ selectivities of 22.3 and 34.4 in wet conditions, respectively. Furthermore, the membrane also showed long-term stability for about 100 hours. Overall, this study showcases the potential of our approach for producing scalable GO-based membranes and underscores the effectiveness of the CO₂-selective membrane for CO₂ separation.