(510c) Facet-Specific Stability of ZIF-8 in the Presence of Acid Gases
In this contribution, we examine the stability of the (110) and (100) crystallographic facets of ZIF-8 under mild acidic conditions. We find that though the (110) facet is more thermodynamically stable than (100), it is more susceptible to degradation by acid exposure. We hypothesize that the mechanism of particle degradation follows a shrinking-core model, with surface imidazolates being replaced by hydroxyls, as suggested by XPS and FTIR studies. Computational investigations support this hypothesis and suggest that the activation barrier for insertion of water into the Zn-MeIm bond is higher on the (100) facet than (110) due to steric constraints. Additionally, the barrier for water insertion is lowered to a greater extent in the presence of SO2 on the (110) facet.