TY - JOUR
T1 - Surface activation of manganese oxide electrode for oxygen evolution from seawater
AU - Izumiya, K.
AU - Akiyama, E.
AU - Habazaki, H.
AU - Kawashima, A.
AU - Asami, K.
AU - Hashimoto, K.
AU - Kumagai, N.
N1 - Funding Information:
This work was supported in part by the Grant-in-Aid for Scientific Research (A) no. 07405032 and (A) no. 06402051 from the Ministry of Education, Science and Culture. One of the authors (K.I.) is grateful to the Research Fellowship of the Japan Society for the Promotion of Science for Young Scientists no. 0284.
PY - 1997
Y1 - 1997
N2 - Utilizing the fact that the equilibrium potential of oxygen evolution is lower than that of chlorine evolution, oxygen evolution in seawater electrolysis was enhanced by decreasing the polarization potential under galvanostatic conditions through increasing the effective surface area of manganese oxide electrodes. Electrodes were prepared by a thermal decomposition method. IrO2-coated titanium (IrO2/Ti electrode) was used as the substrate on which manganese oxide was coated (MnOx/ IrO2/Ti electrode). Subsequently, oxide mixtures of manganese and zinc were coated (MnOx-ZnO/ MnOx/IrO2/Ti electrode). The effective surface area of the MnOx ZnO/MnOx/IrO2/Ti electrodes was increased by selective dissolution of zinc (leaching) into hot 6 M KOH. The oxygen evolution efficiency of the MnOx/IrO2/Ti electrode was 68-70%. Leaching of zinc from the MnOx-ZnO/ MnOx/IrO2/Ti electrodes with 25 mol % or less zinc led to a significant increase in the oxygen evolution efficiency. The maximum efficiency attained was 86% after leaching of zinc from the MnOx-25 mol %ZnO/MnOx/IrO2/Ti electrode. However, large amounts of zinc addition, such as 40 mol % or more are detrimental because of a decrease in the oxygen evolution efficiency. This is due to the formation of a double oxide, ZnMnO3, which is hardly dissolved in hot 6 M KOH.
AB - Utilizing the fact that the equilibrium potential of oxygen evolution is lower than that of chlorine evolution, oxygen evolution in seawater electrolysis was enhanced by decreasing the polarization potential under galvanostatic conditions through increasing the effective surface area of manganese oxide electrodes. Electrodes were prepared by a thermal decomposition method. IrO2-coated titanium (IrO2/Ti electrode) was used as the substrate on which manganese oxide was coated (MnOx/ IrO2/Ti electrode). Subsequently, oxide mixtures of manganese and zinc were coated (MnOx-ZnO/ MnOx/IrO2/Ti electrode). The effective surface area of the MnOx ZnO/MnOx/IrO2/Ti electrodes was increased by selective dissolution of zinc (leaching) into hot 6 M KOH. The oxygen evolution efficiency of the MnOx/IrO2/Ti electrode was 68-70%. Leaching of zinc from the MnOx-ZnO/ MnOx/IrO2/Ti electrodes with 25 mol % or less zinc led to a significant increase in the oxygen evolution efficiency. The maximum efficiency attained was 86% after leaching of zinc from the MnOx-25 mol %ZnO/MnOx/IrO2/Ti electrode. However, large amounts of zinc addition, such as 40 mol % or more are detrimental because of a decrease in the oxygen evolution efficiency. This is due to the formation of a double oxide, ZnMnO3, which is hardly dissolved in hot 6 M KOH.
KW - Manganese oxide electrode
KW - Oxygen evolution
KW - Seawater electrolysis
KW - Surface activation
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U2 - 10.1023/A:1018421028624
DO - 10.1023/A:1018421028624
M3 - Article
AN - SCOPUS:0031344637
SN - 0021-891X
VL - 27
SP - 1362
EP - 1368
JO - Journal of Applied Electrochemistry
JF - Journal of Applied Electrochemistry
IS - 12
ER -