Investigation of the Performance and Durability of Reactive Spray Deposition Fabricated Electrodes on a Bifunctional Membrane for Alkaline Water Electrolysis and CO2 Reduction Reaction

Abstract

Alkaline water electrolysis (AWE) is a promising technology for carbon capture [1]. Anion exchange membrane water electrolyzers (AEMWEs) utilize low-cost, non-precious metal materials, providing an economically viable alternative to more expensive proton exchange membrane water electrolyzers (PEMWEs). While PEMWEs can operate at much higher current densities, they require noble metal catalysts and titanium components for the high potential environment anode [1]. The implementation of a bipolar membrane (BPM) will allow both HER and OER to occur under kinetically favorable conditions [2, 3] by combining both thin AEM and thin PEM layers within a single membrane. AEMs, PEMs, and BPMs have been tested in CO2RR electrolyzers [4]. The BPM may provide a pathway to combine the advantages of both AEMs and PEMs for CO2 reduction. Altering both the membrane and CCM is a focus in the research and development in CO2RR electrolyzers. Lee et al. [5] explored the use of a porous membrane for CO2 reduction. While work can be done to improve performance and crossover, the porous membrane provided excellent mechanical properties and good economic potential.There has been some work done on developing bifunctional membranes for water electrolysis and CO2 reduction [3, 6, 7]. Two key issues with operation of a CO2RR electrolyzer with a BPM is the reactant CO2 that is lost to the AEM and PEM membrane layer interface and the instability of the cell. Both issues contribute to a significant decrease in performance and faradaic efficiency in product conversion. Development of the BPM, both on the membrane’s fabrication and configuration, and electrode layers, needs to be explored to reach higher performances and longer lifespans.In this work, reactive spray deposition technology (RSDT) was used to fabricate electrodes on a UConn fabricated bipolar membrane. Testing of each configuration was conducted as both an AEM water electrolyzer and CO2RR electrolyzer. Polarization, electrochemical impedance spectroscopy, electrochemical equivalent circuits, and distribution of relaxation times were used to investigate cell performance and durability.