High-Quality Thin Films of UiO-66-NH2 by Coordination Modulated Layer-by-Layer Liquid Phase Epitaxy.

Abstract

We report the fabrication of macroscopically and microscopically homogeneous, crack‐free metal‐organic framework (MOF) UiO‐66‐NH2 (UiO: Universitetet i Oslo; [Zr6O4(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).