Simultaneous Intercalation and Assembly of Graphene Oxide and Polydiallyldimethylammonium Chloride (PDDA) for...

Hydrogen will be the energy vector of our future, but cost-effective production of such gas is still far from being established. Nowadays, major issues in hydrogen synthesis are its cost-effective separation from process byproducts, mainly CO₂ or CH₄. Bottom-up fabrication of molecular nanoarchitectures composed of sheets of 2D materials such as graphene oxide (GO) offers a potentially tunable platform to prepare versatile gas membranes able to obtain pure hydrogen for industrial applications. In this work, we assembled a series of PDDA-GO composite nanomaterials with tunable thickness, exploiting the strong interaction between GO and PDDA and varying the number of deposition cycles. Surprisingly, we observed excellent selectivity for hydrogen even after one single deposition cycle, with the membrane ca. 4 nm thick showing the highest permeance. Using extensive characterization with quartz crystal microbalance, atomic force microscopy, X-ray diffractometry, and X-ray photoelectron spectroscopy, we could attribute such an unexpected combination of selectivity/permeance to the formation of an interpenetrated multilayered structure with GO sheets spaced approximately 1.1 nm apart and intercalated by polymer chains, which self-assemble forming an intercalated layered structure even after a single deposition cycle. This approach could significantly reduce the complexity and cost of production for gas separation membranes.