Structure Evolution of Chemically Degraded ZIF-8

Exposure of the metal-organic zeolitic imidazolate framework-8 (ZIF8) to humid SOx gas cleaves Zn-N bonds, leading to framework disorder and a corresponding decrease in pore accessibility. This work shows that framework disorder exhibits a critical behavior with respect to water concentration in the gas stream. While the quantity of sulfate adsorbed at Zn nodes is at or below the detection threshold for the X-ray pair distribution function technique, precluding direct observation of the adsorbate, powder diffraction reveals clear structural alterations. The onset of linker cleavage correlates to a large microstrain that diminishes as framework disorder increases. Energy-dispersive X-ray spectroscopy shows that the sulfur distribution throughout representative grains is uniform, implying the structure transformation is homogeneously nucleated and not dependent upon gas diffusion kinetics.

Automated summary

Exposure of metal-organic zeolitic imidazolate framework-8 (ZIF8) to humid SOx gas results in framework disorder and decreased pore accessibility. The disorder exhibits critical behavior with respect to water concentration, and the cleavage of linkers is correlated to microstrain. The structure transformation is homogeneously nucleated.