Enhanced Permeation through CO2‑Stable Dual-Inorganic Composite Membranes with Tunable Nanoarchitectured Channels

In this work, dual-inorganic composite membranes were prepared with outstanding CO2 separation performance by assembling the largely different aspect-ratio nanostructured materials, including the porous reduced graphene oxide (PRG) and modified halloysite nanotubes (mHNTs), into the Pebax 1657 matrix (CO2 permeability, 124 barrer; ideal CO2/N2 selectivity, 118). This unique separation performance stems from the molecular sieving effect of PRG and preferable stacking behavior between PRG and mHNTs, which improves the efficiency of molecular discrimination and decreases the gas-transport resistance. In addition, the as-prepared membranes show good chemical stability and nearly 500% improvement in CO2 permeability with wet CO2/N2 gas mixture (1/9, v/v). It is also found that the transition of membrane morphology occurs from the PRG-rich nanoarchitecture to mHNTs-rich nanoarchitecture at the mHNTs to PRG mass ratio of 7.5, resulting in an opposite tendency for the CO2/N2 ideal selectivity. Moreover, the as-prepared membranes show great advantage in comparison to the conventional polymeric membranes for carbon capture because of the excellent compaction- and plasticization-resistant behavior.