Onion-Like nanoparticles of the metal–organic framework UiO-66 synthesized by sequential spike crystal growth

Adam F. Cahn, Rebecca L Combs, Ellen M Monzo, Steven Prinslow, Celina M Harris, R. Lee Penn

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Reproducible size and morphology of metal–organic framework (MOF) particles are essential for tuning these materials for applications like heterogeneous catalysis. Particle size measurements from electron micrographs provide information about the impact of changing synthetic parameters on MOF growth, but reported data are usually limited to averages and statistical distributions. Further elucidating synthetic control parameters could facilitate studies of facet-dependent and non-classical growth mechanisms. In this work, phase-pure nanoparticles of the MOF UiO-66 were synthesized using alternating spikes of zirconium and hafnium-based nodes, forming an onion-like structure with alternating layers of Zr-UiO-66 and Hf-UiO-66. In conventional, bright-field transmission electron micrographs, Hf-UiO-66 and Zr-UiO-66 layers appeared darker and lighter, respectively. Alternating layers of Hf-UiO-66 and Zr-UiO-66 were also apparent in elemental maps obtained using scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy. Average particle sizes increased monotonically with each spike, and no Zr-only or Hf-only particles were observed after the first spike, indicating that new material was consistently incorporated onto existing seeds. Surface area of the onion-like particles and their uptake of Ni2+ from solution were both between the values measured for Zr-UiO-66 and Hf-UiO-66. Results demonstrate the use of sequential spikes of nodes in monitoring crystal growth in MOFs.

Original languageEnglish (US)
Article number126911
JournalJournal of Crystal Growth
StatePublished - Jan 1 2023

Bibliographical note

Funding Information:
This work was supported as part of the Inorganometallic Catalyst Design Center, an Energy Frontier Resource Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under award DE-SC0012702. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from the NSF through the MRSEC (Award Number DMR-2011401) and the NNCI (Award Number ECCS-2025124) programs. Research reported in this publication was supported by the Office of the Vice President of Research, College of Science and Engineering, and the Department of Chemistry at the University of Minnesota.

Publisher Copyright:
© 2022 Elsevier B.V.


  • A1 Characterization
  • A1 Crystal Morphology
  • A1 X-ray Diffraction
  • A2 Seed Crystals
  • B1 Metal–Organic Frameworks
  • B1 Nanomaterials

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