In Situ Observations of Abnormal Pore Size Changes of a Zirconium Based Metal-Organic Framework Using Atomic Resolution S/TEM and EELS

Metal-organic frameworks (MOFs) have garnered interest due to the high surface area and uniform controlled porosity of the structure which have been used for a number of purposes including gas separation, water filtration, catalysts for the petrochemical industry, and gas storage More specific functionality, such as becoming a support for single atom catalysts and incorporating undercoordinated metal centers, often depends on additional post-synthesis modifications of the structure. Understanding the structure and the process for the post-synthesis modifications at the atomic level allows for greater control. Electron microscopy has recently been employed to understand the synthesis of MOFs as well as modifications to the structure. However, in situ works detailing the evolving structures at high spatial resolution are missing, because the organic component of MOFs can be damaged by the intense electron beam. Here, we show the combination of aberration-corrected scanning/transmission electron microscopy (S/TEM) combined with electron energy loss spectroscopy (EELS) during in situ heating offers visualization and an understanding of the structure changes of a MOF with a zirconium oxide network.