Acta Chimica Sinica ›› 2012, Vol. 70 ›› Issue (10): 1166-1172.DOI: 10.6023/A1201131 Previous Articles     Next Articles

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钌镧氧化物涂层在NaCl 溶液中的电化学阻抗谱(EIS)研究

龙萍a,c, 李庆芬b, 许立坤c, 薛丽莉a, 宋泓清c   

  1. a 哈尔滨工程大学材料科学与化学工程学院 哈尔滨 150001;
    b 哈尔滨工程大学机电工程学院 哈尔滨 150001;
    c 中国船舶重工集团公司第七二五研究所 海洋腐蚀与防护重点实验室 青岛 266071
  • 投稿日期:2012-01-13 修回日期:2012-02-21 发布日期:2012-05-28
  • 通讯作者: 龙萍

Electrochemical Impedance Spectroscopy (EIS) Study of Ru-La Oxide Coatings in NaCl Solution

Long Pinga,c, Li Qingfenb, Xu Likunc, Xue Lilia, Song Hongqingc   

  1. a School of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001;
    b School of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001;
    c State Key Laboratory for Marine Corrosion and Protection, Luoyang Ship Material Research Institute, Qingdao 266071
  • Received:2012-01-13 Revised:2012-02-21 Published:2012-05-28

Electrochemical surface structure and electrochemical performance of Ti based Ru-La oxide coatings in 3.5% NaCl solution have been investigated by electrochemical impedance spectroscopy (EIS), together with cyclic voltammetry (CV) and scanning electron microscopy (SEM). The best-fit circuit to EIS data of the coatings in the absence of the chlorine evolution reaction is Rs(RctQdl), and that in the potential range of chlorine evolution reaction is Rs(RfQf)(RctWQdl). The high-frequency region corresponds to the impedance behavior of the coating, and the low-frequency region to that of the interface between outer surface and electrolyte. Results show that the pseudo-capacitances of the oxide film and the double layer increase with increasing La content, reaching a maximum at the nominal La content of 30 mol%. This finding agrees with the CV result, suggesting that the La additive in suitable amount can improve the electrochemical activity of the RuO2 coating. The electric conductivity of the coatings, however, significantly decreases when nominal La content is larger than 30 mol% in the region of the chlorine evolution potential. A character with a Warburg impedance at low-frequency region suggests the relationship to passivation of the coating surface and specific adsorption, resulting in a dramatic decrease of electrocatalytic activity of the coatings at norminal La content of 70 mol%.

Key words: electrochemical impedance pedance spectroscopy, electrocatalysis, oxide coating, lanthanum, RuO2