Water-Based Electrooxidation of Cyclohexene in a Novel Liquid Diffusion Electrode Reactor Design

As renewably produced electricity becomes increasingly economical and abundant, electrocatalysis is expected to play a key role in the production of societally important fuels and chemicals to enable a sustainable future. In this work, we demonstrate the feasibility of a novel liquid diffusion electrode reactor design that enables the electrooxidation of neat cyclohexene. This design allows for the reaction of two immiscible liquids at an engineered electrode interface, forgoing the need for cosolvents that are necessary in single phase electroorganic reactions as well as facilitating opportunities for enhanced product separation. Cell performance is assessed as a function of operating potential and in the presence of a variety of catalysts shown to be active toward organic substrate oxidation in traditional heterogeneous catalysis. We find that carbon paper alone can oxidize cyclohexene into a variety of products and displays a Faradaic efficiency greater than 50% toward these products when operated at 1.8 V vs the reversible hydrogen electrode. Addition of metal oxide catalysts increases overall cell activity by up to three times without sacrificing Faradaic efficiency. Overall, this work demonstrates and characterizes the capabilities of a liquid diffusion electrode cell for the oxidation of pure organic compounds that are immiscible with water, enabling a new paradigm of organic electrocatalysis.