Facet-Specific Stability of ZIF-8 in the Presence of Acid Gases Dissolved in Aqueous Solutions
Journal Article
·
· Chemistry of Materials
- Georgia Inst. of Technology, Atlanta, GA (United States)
ZIF-8 is a crystalline microporous material that has been widely studied because of its thermal and chemical stability relative to other metal–organic frameworks (MOFs) and its potential for use in a number of gas adsorption, separation, and catalysis applications. However, most studies focus on characterization of the bulk structure of ZIF-8, ignoring the potential effect of the particle shape and the external surface on these applications. This report describes studies that examined the stability of the {110} and {100} crystallographic facets of ZIF-8 under mildly acidic conditions. Though the {110} facet is more thermodynamically stable than the {100} facet, it is found to be more susceptible to degradation by acid exposure. It is hypothesized that the mechanism of particle degradation follows a shrinking-core model, with surface imidazolates being replaced by hydroxyls, as suggested by complementary X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy characterization. Computational investigations support this hypothesis and suggest that the reaction energy for insertion of water into the Zn–MeIm bond is more favorable on the {110} facet than on the {100} facet because of steric constraints. Additionally, the reaction energies are more favorable on both surfaces in the presence of SO2. These findings have implications for the formation of surface barriers that can affect mass transfer into or out of the ZIF crystals. This study represents the first comprehensive investigation of differences between exposed surface facets of a MOF.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Center for Understanding and Control of Acid Gas-induced Evolution of Materials for Energy (UNCAGE-ME)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- SC0012577
- OSTI ID:
- 1388040
- Journal Information:
- Chemistry of Materials, Journal Name: Chemistry of Materials Journal Issue: 19 Vol. 28; ISSN 0897-4756
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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