Title: Facet-Specific Stability of ZIF-8 in the Presence of Acid Gases Dissolved in Aqueous Solutions

Abstract

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 themore » 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.« less

Authors:

Pang, Simon H. ^[1]; Han, Chu ^[1]; Sholl, David S. ^[1]; Jones, Christopher W. ^[1]; Lively, Ryan P. ^[1]

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+ Show Author Affiliations

1. Georgia Inst. of Technology, Atlanta, GA (United States)

Publication Date:

Wed Sep 21 00:00:00 EDT 2016

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Center for Understanding and Control of Acid Gas-induced Evolution of Materials for Energy (UNCAGE-ME)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1388040

Grant/Contract Number:  

SC0012577

Resource Type:

Accepted Manuscript

Journal Name:

Chemistry of Materials

Additional Journal Information:

Journal Volume: 28; Journal Issue: 19; Related Information: UNCAGE-ME partners with Georgia Institute of Technology (lead); Lehigh University; Oak Ridge National Laboratory; University of Alabama; University of Florida; University of Wisconsin; Washington University in St. Louis; Journal ID: ISSN 0897-4756

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; catalysis (heterogeneous); defects; membrane; carbon capture; materials and chemistry by design; synthesis (novel materials); synthesis (self-assembly); synthesis (scalable processing)