Redox-Hopping and Electrochemical Behaviors of Metal-Organic Framework Thin Films Fabricated by Various Approaches

In this study, spatially dispersed redox-active iridium sites are installed on the nodes of a zirconium-based metal-organic framework (MOF), UiO-66, utilizing a self-limiting solution-phase solvothermal deposition in MOF technique. Thin films of the resulting iridium-decorated UiO-66 are then fabricated on conducting substrates by three distinct approaches: drop-casting, spin-coating, and bottom-up solvothermal methods. The redox-hopping and electrochemical behaviors of the iridium-decorated UiO-66 thin films fabricated by distinct methods are investigated. The findings indicate that the rate of charge hopping in these redox-active MOF thin films is not significantly affected by both the method for fabricating thin films and the film thickness. However, remarkably distinct electrochemical behaviors are observed for the iridium-decorated UiO-66 thin films fabricated by different approaches, which suggests that the approach for fabricating MOF thin films may play an important role in the performances of the targeted electrochemical applications.