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 clean production of hydrogen and desalinated water. The high concentration of chloride containing salts in seawater, however, results in competition between the evolution of oxygen and toxic chlorine gas at the anode. Our goal is to understand and control an electrode’s activity and selectivity towards these products in seawater electrolysis. To accomplish this goal, electrodes with varying compositions of dopants electrodeposited onto iridium oxide-coated titanium substrates were tested by analyzing and comparing the performance of each electrode via cyclic voltammetry and chronoamperometry. The selectivity of oxygen evolution and chlorine evolution was determined analytically using iodometric titration. The deposition method used to create the electrode, composition of the electrode, and type of electrolyte all impact an electrode’s selectivity. By comparing the performance of various electrodes, we identify earth-abundant metals with high catalytic activity towards oxygen evolution over chlorine evolution and obtain a greater understanding of what materials are efficient and selective towards oxygen evolution. This understanding guides future design of better electrodes to advance seawater electrolysis technology for hydrogen production.

Seawater electrolysis: Understanding the selectivity of oxygen/chlorine evolution for metal oxide catalysts

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.