High‐Quality Thin Films of UiO‐66‐NH2 by Coordination Modulated Layer‐by‐Layer Liquid Phase Epitaxy. Issue 33 (13th May 2021)

• Record Type: Journal Article
• Authors: Semrau, A. Lisa; Fischer, Roland A.
• Is Part Of: Chemistry. Volume 27:Issue 33(2021)
• Page Start: 8509
• Page End: 8516
• Publication Date: 2021-05-13
• Subjects: CM-LPE -- metal-organic frameworks -- SURMOFs -- thin films -- UiO-66-NH2; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202005416
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: We report the fabrication of macroscopically and microscopically homogeneous, crack‐free metal‐organic framework (MOF) UiO‐66‐NH2 (UiO: Universitetet i Oslo; [Zr6 O4 (OH)4 (bdc‐NH2 )6 ]; bdc‐NH2 2− : 2‐amino‐1, 4‐benzene dicarboxylate) thin films on silicon oxide surfaces. A DMF‐free, low‐temperature coordination modulated (CM), layer‐by‐layer liquid phase epitaxy (LPE) using the controlled secondary building block approach (CSA). Efficient substrate activation was determined as a key factor to obtain dense and smooth coatings by comparing UiO‐66‐NH2 thin films grown on ozone and piranha acid‐activated substrates. Films of 2.60 μm thickness with a minimal surface roughness of 2 nm and a high sorption capacity of 3.53 mmol g −1 MeOH (at 25 °C) were typically obtained in an 80‐cycle experiment at mild conditions (70 °C, ambient pressure). Abstract : Dense, crack‐free, and crystalline UiO‐66‐NH2 thin films were grown on silicon dioxide surfaces by coordination modulated liquid phase epitaxy (CM‐LPE). In a stepwise process, the substrate was alternatively immersed in Zr6 O4 (OH)4 (OMc)12 and H2 ‐bdc‐NH2 ethanol solutions which both contain methacrylic acid as a coordination modulator. For optimal thin film quality, the ideal activation of the SiO2 substrate prior to the thin film growth is key, whereby piranha acid is superior to ozone treatment.