ZIF-8 Vibrational Spectra: Peak Assignments and Defect Signals

Mueed Ahmad, Roshan Patel, Dennis T. Lee, Peter Corkery, Andrea Kraetz, None Prerna, Samuel A. Tenney, Dmytro Nykypanchuk, Xiao Tong, J. Ilja Siepmann, Michael Tsapatsis, J. Anibal Boscoboinik

Research output: Contribution to journalArticlepeer-review

Abstract

Zeolitic imidazolate framework (ZIF-8) is a promising material for gas separation applications. It also serves as a prototype for numerous ZIFs, including amorphous ones, with a broader range of possible applications, including sensors, catalysis, and lithography. It consists of zinc coordinated with 2-methylimidazolate (2mIm) and has been synthesized with methods ranging from liquid-phase to solvent-free synthesis, which aim to control its crystal size and shape, film thickness and microstructure, and incorporation into nanocomposites. Depending on the synthesis method and postsynthesis treatments, ZIF-8 materials may deviate from the nominal defect-free ZIF-8 crystal structure due to defects like missing 2mIm, missing zinc, and physically adsorbed 2mIm trapped in the ZIF-8 pores, which may alter its performance and stability. Infrared (IR) spectroscopy has been used to assess the presence of defects in ZIF-8 and related materials. However, conflicting interpretations by various authors persist in the literature. Here, we systematically investigate ZIF-8 vibrational spectra by combining experimental IR spectroscopy and first-principles molecular dynamics simulations, focusing on assigning peaks and elucidating the spectroscopic signals of putative defects present in the ZIF-8 material. We attempt to resolve conflicting assignments from the literature and to provide a comprehensive understanding of the vibrational spectra of ZIF-8 and its defect-induced variations, aiming toward more precise quality control and design of ZIF-8-based materials for emerging applications.

Original languageEnglish (US)
Pages (from-to)27887-27897
Number of pages11
JournalACS Applied Materials and Interfaces
Volume16
Issue number21
DOIs
StatePublished - May 29 2024

Bibliographical note

Publisher Copyright:
© 2024 American Chemical Society.

Keywords

  • IR spectra
  • MOFs
  • ZIFs
  • defects in ZIFs
  • peak assignments
  • vibrational spectroscopy

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