Electrolyte Engineering for Oxygen Evolution Reaction Over Non‐Noble Metal Electrodes Achieving High Current Density in the Presence of Chloride Ion

Direct seawater electrolysis potentially simplifies the electrolysis process and leads to a decrease in the cost of green hydrogen production. However, impurities present in the seawater, especially chloride ions (Cl(−)), cause corrosion of the electrode material, and its oxidation competes with the anodic oxygen evolution reaction (OER). By carefully tuning electrode substrate and electrolyte solutions, the CoFeO( x )H( y )/Ti electrode with high double‐layer capacitance actively and stably electro‐catalyzed the OER in potassium borate solutions at pH 9.2 in the presence of 0.5 mol kg(−1) Cl(−). The electrode possesses an active site motif composed of either a Co‐ or Fe‐domain and benefits from an enlarged surface area. Selective OER was demonstrated in Cl(−)‐containing electrolyte solutions at an elevated reaction temperature, stably achieving 500 mA cm(−2) at a mere potential of 1.67 V vs. reversible hydrogen electrode (RHE) at 353 K for multiple on‐off and long‐term testing processes with a faradaic efficiency of unity toward the OER.