J. Japan Inst. Metals, Vol. 68, No. 7 (2004),
pp. 447-455

Anodically Deposited Mn-Mo-Fe Oxide Anodes for Oxygen Evolution in Hot Seawater Electrolysis

Nabil A. Abdel Ghany^1,, Shinsaku Meguro¹, Naokazu Kumagai², Katsuhiko Asami³ and Koji Hashimoto^1,

Abstract:

In order to avoid chlorine evolution on the anode in hot seawater electrolysis, the oxygen evolution anodes were tailored. γ-MnO₂-type Mn_1-x-yMo_xFe_yO_2+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.

(Received 2004/3/31)

Keywords:

hot seawater electrolysis, anode, oxygen evolution, manganese-molybdenum-iron oxide, 100% oxygen evolution efficiency, deposition efficiency

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