Electrodeposition of Metal-Organic Framework Thin Films: Design, Fabrication, and Applications

Abstract

Metal-organic frameworks (MOFs) are a distinctive class of hybrid organic-inorganic materials composed of periodically arranged metal nodes and organic linkers. These materials have attracted considerable attention across a wide range of disciplines, including catalysis, gas storage, drug delivery, sensing, optoelectronics, and magnetism. However, the efficient utilization of MOFs in practical applications depends on their integration into devices, which requires their fabrication into thin film configurations to enable advanced functionalities.This thesis primarily focuses on the fabrication of MOF thin films by employing the cathodic deposition technique. In this work, a variety of MOF thin films were synthesized using different metal centers, including 3d-metals such as Cobalt, Nickel, Copper, and lanthanides such as Europium (Eu), and Terbium (Tb), in combination with ligands possessing distinct functional groups - such as TCNQ and carboxylate-based ligands like ADA and BTB. As-synthesized electrodeposited thin films display excellent uniformity, crystallinity, and phase purity. In Chapter-2, bimetallic Co-Ni-TCNQ thin films were synthesized alongside their monometallic analogue and subsequently examined for the electrochemical oxygen evolution reaction. In Chapter-3, Ln-ADA (Ln-Tb and Eu) MOF thin films were fabricated and thoroughly characterized. Thermally-driven conformational twist has been observed at 400 K for the as-synthesized MOF thin films. Additionally, TCNQ as a guest molecule was introduced to further study the temperature-dependent twist phenomenon. In Chapter-4, carboxylic linker-based Ln MOF thin films were synthesized, and photophysical studies have been performed to explore the potential in sensing and anti-counterfeiting applications. In Chapter-5, the electrodeposition technique was introduced into the energy harvesting field to enable direct deposition of thin films on conducting substrates, thereby improving adhesion and enabling seamless charge transfer for triboelectric applications.