Mind the gap: The thermodynamic potential gap between chloride oxidation and oxygen evolution reaction (OER) as shown in the blue area allows the CoFeO
electrocatalyst to produce O2 with near 100 % faradaic efficiency toward the OER even in the presence of chloride ions at any temperature.
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
/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.Zum Volltext