<p>Metal-organic
frameworks (MOFs) are known for their versatile combination of inorganic
building units and organic linkers, which offers immense opportunities in a
wide range of applications. However, many MOFs are typically synthesized as multiphasic
polycrystalline powders, which are challenging for studies by X-ray
diffraction. Therefore, developing new structural characterization techniques is
highly desired in order to accelerate discoveries of new materials. Here, we report
a high-throughput approach for structural analysis of MOF nano- and sub-microcrystals
by three-dimensional electron diffraction (3DED). A new zeolitic-imidazolate
framework (ZIF), denoted ZIF-EC1<a>, </a>was first discovered in a trace amount during the
study of a known ZIF-CO<sub>3</sub>-1 material by 3DED. The structures
of both ZIFs were solved and refined using 3DED data. ZIF-EC1 has a dense 3D framework structure, which is built by
linking mono- and bi-nuclear Zn clusters and 2-methylimidazolates (mIm<sup>-</sup>). With a composition
of Zn<sub>3</sub>(mIm)<sub>5</sub>(OH),
ZIF-EC1 exhibits
high N and Zn densities. We show that the N-doped carbon material derived from ZIF-EC1
is a promising electrocatalysis for oxygen reduction reaction (ORR). The
discovery of this new MOF and its conversion to an efficient electrocatalyst highlights
the power of 3DED in developing new materials and their applications. </p>