Routes to Avoiding Chlorine Evolution in Seawater Electrolysis: Recent Perspective and Future Directions

The prospective of exploring “abundantly available electrolytes”, i.e. seawater, as an electrolyte feedstock in electrolyzers is realized recently for supplying unlimited and uninterrupted hydrogen as an energy source. However, seawater splitting possesses severe challenges, due to the presence of different interfering ions. Among these, the presence of chloride ions in seawater poses serious concerns, as it leads to the formation of toxic chlorine-based gaseous and aqueous oxidation products (Cl₂, OCl^-) during electrolysis. To solve this issue, different approaches are explored, which involve the chemical tuning of the electrolyte, electrodes, and the electrolyzer geometry. However, no report in the literature has summarized these approaches, which can provide a basis for any innovative future research. Herein, for the first time, we have reviewed the current different approaches for avoiding chloride oxidation during seawater electrolysis, critically highlighting their advantages and disadvantages while giving a critical perspective for any future research in the field.