Zeolite imidazole framework-8 (ZIF-8), a representative member of the ZIF class, is a new microporous
material considered to have strong potential for use in many important industrial applications, such as
hydrogen purification and storage and catalyst support for carbon monoxide oxidation. In this work,
we evaluate the applicability of ZIF-8 as a catalyst (support) by reporting its thermal stability under
various gaseous environments. The thermal stability tests indicate that ZIF-8 exhibits its highest stability
under an inert environment, followed by an oxidative environment, and exhibits the worst stability in a
steam atmosphere. The results of thermogravimetric analysis (TGA) clearly suggest that the stability of
the ZIF-8 structure depends strongly on the gas-phase environment as well as on its exposure time.
Hydrogen reduction and CO oxidation of Au/ZIF-8 was performed to verify the structural stability of
the framework under common preparation and application conditions used for supported Zeolitic imidazolate frameworks (ZIFs) have been widely investigated for
numerous applications including energy storage, heterogeneous catalysis, and greenhouse gas
adsorption. Much of the early work has focused on the bulk properties of microcrystalline ZIFs.
Herein, we focus on identifying the nature of the surface of ZIF-8 by studying a supported ZIF-
8 nanoparticle film using surface characterization techniques. We have experimentally identified
the presence of a zinc-rich surface terminated by carbonates and water/hydroxyl groups (in
addition to the expected methylimidazole terminations) using X-ray photoelectron spectroscopy
(XPS). The thermal stability of ZIF-8 thin films was also investigated using scanning electron
microscopy (SEM) and temperature-programmed reaction spectroscopy (TPRS). We
determined the onset of decomposition of ZIF-8 thin films to be approximately 630 K using
TPRS in an ultrahigh vacuum (UHV) environment. This work presents the first characterization
steps needed to study the evolution of ZIF surfaces in situ using surface characterization
techniques. Such techniques are capable of determining reaction products and tracking
intermediates and surface evolution in gas adsorption/reaction studies of thin films.