Anodically deposited Mn-Mo-Fe oxide anodes for oxygen evolution in hot seawater electrolysis

In order to avoid chlorine evolution on the anode in hot seawater electrolysis, the oxygen evolution anodes were tailored. gamma-MnO2-type Mo1-x-yMoxFeyO2+x-0.5y anodes consisting of Mn4+, Mo6+ and Fe3+ were prepared by anodic deposition. The anodes with the 100% oxygen evolution efficiency in the electrolysis of 0.5 kmol m(-3) NaCl at pH 12, 353 K and a current density of 1000 Am-2 were prepared in solutions consisting of 0.003 kmol m(-3) Na2MoO4, 0.1 kmol m(-3) Fe(NH4)(SO4)(2) and 0.2 kmol m(-3) or higher concentrations of MnSO4 at pH 0.33-0.5, 363 K and a current density of 600 Am-2. In the outside of this range, generally because of lower deposition efficiency, the electrode surface was not completely covered with anodically deposited oxides with a consequent lower oxygen evolution efficiency.