Enhanced thermal stability and selectivity of GO/BN composite membranes via ionic liquid intercalation for efficient H2 purification

Graphene oxide (GO) lamellar membranes hold significant promise for gas separation but suffer from structural instability, particularly under high temperature, which deteriorates their separation performance. To address this, we developed a composite membrane by incorporating exfoliated boron nitride (BN) nanosheets into a GO matrix, followed by ionic liquid (IL) intercalation. Liquid nitrogen (LN 2 )-exfoliated BN nanosheets, characterized by uniformity and rigidity, were integrated to construct stable interlayer nanochannels. The resulting GO/BN-LN 2 membrane achieved a H 2 /CO 2 selectivity of 15.5 with a H 2 permeance of 505 GPU (gas permeation unit). More importantly, the intercalation of ILs (e.g., [Bmim][TF 2 N]) into the GO/BN interlayers yielded a synergistic enhancement. The ILs functioned as a selective CO 2 -absorbing layer and a “thermal buffer”, significantly improving the membrane's thermal stability. Consequently, the optimized GO/BN@IL composite membrane (d-spacing is 7.9 Å, and membrane thickness is 0.88 μm) maintained excellent performance at 363 K, exhibiting a markedly enhanced H 2 /CO 2 selectivity of 23.26 and a high H 2 permeance of 1020 GPU. This work demonstrates a facile strategy to simultaneously boost the selectivity, permeance, and thermal resilience of 2D lamellar membranes, showcasing their great potential for high-temperature H 2 purification applications.