Direct seawater electrolysis through in situ purification using dual ion exchange membranes

Seawater electrolysis for hydrogen production has attracted considerable interest due to its sustainability and the abundant availability of seawater. However, the complex composition of seawater poses challenges, such as interference from impurity ions and electrode corrosion caused by chloride ions. In this study, we propose a method for direct seawater utilization in electrolytic hydrogen production, using a combination of anion and cation exchange membranes (AEM and CEM) to effectively prevent ion crossover between seawater and the electrolyte. After 5 consecutive days of electrolysis under optimal conditions, the pH change in the electrolyte was less than 0.1, magnesium and calcium ions from seawater were nearly undetectable on the electrode surfaces, and chloride ion concentrations remained below 100 mM. Our results demonstrate that the combination of AEM and CEM effectively protects the electrodes from seawater impurities, underscoring the feasibility of directly utilizing seawater for hydrogen production through electrolysis.