Energy Storage with Seawater Electrolysis: Ability of Oxide Coatings to Manipulate Selectivity Towards Oxygen/Chlorine Evolution at a Buried Interface

Energy is a globally valued resource. In order to meet energy demands in the face of climate change, developing efficient methods of storing renewable energies is essential. A clean method to store energy is through the electrochemical splitting of water. Such a reaction can be driven by renewable energy sources like solar energy. In this project, an abundant natural resource is explored as an electrolyte for electrolysis—seawater. The electrolysis of seawater evolves hydrogen and oxygen gas, which can act as fuels when recombined in a fuel cell to generate electricity, heat, and desalinated water. This technology holds promising potential for the clean production of hydrogen and desalinated water. The major benefit of utilizing seawater as a feedstock is the preservation of fresh water sources. However, the high concentration of chloride salts in seawater poses challenges, resulting in competition between the oxygen evolution reaction (OER) and chlorine evolution reaction (CER) at the anode. Our goal is to understand and control an electrode’s activity and selectivity towards OER in seawater electrolysis. To accomplish this goal, electrodes with varying thicknesses of manganese oxide (MnOx) were electrodeposited onto iridium oxide (IrOx) coated glassy carbon substrates. The performance of each electrode in neutral chloride solution was compared through rotating ring-disk electrode cyclic voltammetry. From initial testing, MnOx decreases CER selectivity. While further testing is needed, initial tests indicate increasing thickness of MnOx films increases selectivity towards OER. This understanding informs future design of better electrodes to advance seawater electrolysis technology for hydrogen production.