Flexible and Rapid Synthesis of Bimetallic Metal–Organic Framework Thin Films

Abstract

Metal–organic frameworks (MOFs) have many applications specific to thin films including coatings, separation, and catalysts. This work presents a synthesis method for the creation of bimetallic thin-film MOFs rapidly and reproducibly at ambient conditions. A dynamic spin-coating approach is used to synthesize the MOF thin film onto inert surfaces without the use of a self-assembled monolayer and without pretreatment. These thin films are characterized for coverage, crystallinity, and size through scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. These methods are also used to confirm the MOF structure and incorporation of the secondary metal. Secondary metals zinc, nickel, and cobalt were successfully integrated into the copper HKUST-1 structure, producing three unique bimetallic MOF structures. Growth parameters such as metal precursor salts, evaporation effects on coverage and crystallinity, and substrate effect under ambient conditions were correlated with the crystal size and surface coverage of the crystallites to understand the conditions required for bimetallic MOF growth as thin films allow them to be optimized for a variety of applications in catalysis, separations, and materials science.