Chloride Ions Resistance Strategies in Seawater Electrolysis

Seawater electrolysis is regarded as one of the most promising and necessary methods for generating a large quantity of green hydrogen to fulfill the energy storage requirement. Nevertheless, the practical implementation of seawater splitting remains difficult because of the electrochemical challenge caused by various elements existing in seawater, among which chloride ions (Cl^-) are the most detrimental, causing significant damage to the electrodes. In this review, the challenges posed by Cl^- in seawater electrolysis, including chloride oxidation and corrosion caused by chlorine or chloride, are initially discussed. Then, recently reported efficient and stable electrocatalysts in seawater electrolysis are described, with a particular focus on discussing strategies for resisting Cl^-, such as protective coating, polyanion layer, stable structure, and alkaline microenvironment. Subsequently, the alternative strategies, including HER coupled electrooxidation, seawater pretreatment, chlorine utilization, and membrane design, to circumvent the adverse effects of Cl^- are presented. Eventually, the challenges and future outlooks of this field are summarized.