Gas Separation through Graphene Nanopores Enabled by Thermally Robust Porous Organic Polymer Reinforcement

Abstract

Porous single-layer graphene (PG) offers an ideal platform for molecular-sieving membranes due to its atomically thin inorganic lattice and its ability to incorporate molecularly selective pores. However, the use of PG for high-temperature gas separation remains limited by the lack of a mechanically reinforcing film (MRF) that enables crack-free transfer onto porous supports and stable operation under pressurization. Here, we introduce a fluorinated porous organic polymer (FPOP) that provides the mechanical and thermal robustness needed to operate PG membranes at high temperature. The FPOP layer is deposited directly on PG from a molecular precursor solution. Upon drying and thermal annealing, it develops into a continuous cross-linked film that conforms to PG, maintains strong adhesion, and helps to avoid crack formation during the transfer of PG to a macroporous support. The FPOP film exhibits a quasi-ordered structure, forms an interface with graphene, and remains stable under pressurized conditions up to 350 °C. FPOP-supported PG membranes exhibit selective gas transport at elevated temperature (350 °C) and maintain their performance during extended mixed-gas operation. The membranes retain selective transport after humid/oxidative exposure and ambient storage. Importantly, the porous FPOP can regulate transport through enlarged nonselective graphene defects, thereby improving the selectivity of PG membranes. Overall, we demonstrate FPOP as a thermally stable MRF platform that enables crack-free PG transfer, high-temperature operation, and regulation of nonselective transport pathways.