Promoter Effects of Rare Earth Ions on Electrocatalytic Oxidation of Methanol

Chinese Chemical Letters Vol. 13, No. 6, pp 489 - 490, 2002489 .http://www.imm.ac .cn/journal/ccl/htmlPromoter Effects of Rare Earth Ions on Electrocatalytic Oxidation ofMethanolJing Hua LIU', Wei XING', Hui YANG, Tian Hong LU3*'Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022,"Department of Chemistry, Nanjing Normal University, Nanjing 210097Abstract: The promoter effects of rare earth ions on the electrocatalytic oxidation of methanol atthe Pt electrode were studied using the cyclic voltammetry and stable polarization techniques.Iwas found for the first time that Euv Ho、 Dy ions could accelerate the electrocatalytic oxidation ofmethanol at the Pt electrode, while Lu, Pr、 Yb、 Sm ions showed inhibitor effects.Keywords: Rare earth, methanol, electrocatalytic oxidation.the direct methanol fuel cell. Thus, a number of groups pay attention to find the activeanode catalysts for promoting the oxidation of methanol. In this paper, it was foundthat some rare earth ions could promote the anodic oxidation reaction of methanol.The electrochemical measurements were carried out with CHI potentiostat (CHI Co.U.S.A.) and traditional thre-lectrode cell. A Pt wire and saturated calomel electrodewere used as the auxiliary and reference electrodes, respectively. The workingelectrode is the smooth Pt electrode. The apparent surface area of the Pt electrode is0.03 cnt. The electrolyte is 0.5 mol/L CH,OH + 0.5 mol/L HSO4 with or without the0.1 mol/L rare earth ion. Usually, the electrochemical measurements were carried out at25°C.peaks of the electrocatalytic oxidation of methanol at the Pt electrode in the electrolyteswith and without rare earth ions are located at about 0.62 V. However, the peak currentsin the electrolytes with the Eu, Ho or Dy ions are higher than that of without the rareearth ions, while the peak currents in the electrolytes with the Sm, Lu, Yb or Pr ions arelower than that of without the rare earth ions.The measurements of the polarization curves indicated that the polarizationperformances of the electrocatalytic oxidation of methanol in the electrolyte with Ho, Euor Dy ions are better than that of without the rare earth ions, while the polarizationperformances in the electrolyte with Sm, Lu, Yb or Pr ions are worse than that of withoutthe rare earth ions. Figure 1 shows the polarization curves of the electrocatalyticoxidation of methanol at the Pt electrode in the electrolytes with Pr (Curve a, Eu(Curve C) and without rare earth ions (Curve b).中国煤化工MYHCNMH G.490Jing Hua LIU et al.Figure 1. The polarization curves of the Pt electrode in the 0.5 mol/L CH,OH + 0.5 mol/L H,SO,solution with (a) Pr, (C) Eu and (b) without rare earth ions.7-0.6> 0.4国0.30.000.Current /mA cm^2All the facts mentioned above indicated that the Eu, Ho and Dy ions in theelectrolyte could accelerate the electrocatalytic oxidation of methanol at the Pt electrodeand Sm, Lu, Yb and Pr showed the inhibitor effects. Further study is in progress.AcknowledgmentsThe authors are grateful for the financial supports of 973 Program, National Science andTechnology Commission, China (G2000026408), the National Natural Science Foundation ofChina (20003005), Natural Science Foundation Jilin Province, (20000510) and Natural ScienceFoundation Jiangsu Province, (BQ000009).Reference1. W. Mitchell, Fuel Cells, Academic Press, 1963, 9.Received 27 August, 2001中国煤化工MHCNMH G.