Molecular Mechanism of Reversible Gas Adsorption and Selectivity in ZIF-90

Zeolitic imidazolate frameworks (ZIF)─a class of metal–organic frameworks that connect metal atoms by imidazole linkers─poses unique properties including tunable pore size and selective adsorption. Here, we combine experiments and computations to establish the mechanisms underpinning reversible gas adsorption and selectivity in ZIF-90. Our experiments, quantum chemical density functional theory (DFT), and classical grand canonical Monte Carlo (GCMC) simulations consistently suggest a gas-species-dependent heat of adsorption underlying the gas selectivity in ZIF-90. Moreover, our molecular dynamics (MD) simulations suggest that gas adsorption is dynamic and reversible in nature. This is further verified by pressure swing experiments that show reversible gas adsorption in ZIF-90 over multiple cycles without deterioration of its structure and performance. The present study interconnects modern computational tools and experiments and provides a fundamental understating that has important implications for porous material design.