Electrochemical Characterization of Hydrocarbon Bipolar Membranes with Varying Junction Morphology

Current water electrolysis technology is limited to operation at a single pH through the use of ion exchange membranes or traditional liquid alkaline systems. Using a bipolar membrane, comprised of both a cation and anion exchange membrane, operation across a pH gradient may be achieved, with the hydrogen and oxygen evolution reactions occurring in acidic and basic media, respectively. In this work, we focus on the characterization of hydrocarbon bipolar membranes for electrolytic water splitting based on two emerging classes of hydrocarbon ion-conducting polymers. The influence of the cation and anion exchange membrane interface on the efficiency of water dissociation is explored using two types of 3D, dual-fiber electrospun junctions. The results support the view that both high interfacial surface area and inclusion of Al(OH)3 enhance water dissociation under high current densities and affect the rate of ion leakage under open circuit potential. While dual-fiber electrospun interfacial layers were found to provide high junction surface areas, poor adhesion of some hydrocarbon-based polymers is observed due to their relatively high glass transition temperature. This restricts the formation of a strong interfacial layer, as the different polymers are unable to properly entangle while in the glass phase.