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电化学(中英文) ›› 2004, Vol. 10 ›› Issue (3): 279-286. 

• 研究论文 • 上一篇    下一篇

Pt在多晶Au微盘电极上电沉积成核与晶体生长

陶芝勇,刘佩芳   

  1. 武汉大学化学与分子科学学院,武汉大学化学与分子科学学院 湖北武汉430072 ,湖北武汉430072
  • 收稿日期:2004-08-28 修回日期:2004-08-28 出版日期:2004-08-28 发布日期:2004-08-28

Nucleation and Crystal Growth of Pt Electrodeposition on Poly Crystal Au Microdisc Electrode

TAO Zhi-yong, LIU Pei-fang~   

  1. (*) (College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072, China
  • Received:2004-08-28 Revised:2004-08-28 Published:2004-08-28 Online:2004-08-28

摘要: 于不同H2PtCl6浓度和超电势下,应用Fleischmann的电结晶成核及晶体生长模型和Barradas Bosco的电化学成相吸附成核模型,拟合多晶Au微盘电极( =30μm)上电沉积Pt的恒电势阶跃电流暂态曲线.得出:在稀H2PtCl6溶液中,上述沉积过程初期,发生H2PtCl6吸附并遵循二维瞬时成核与圆柱形生长模型.二维生长速率常数随超电势线性增加.跟随其后的是核的层状生长,其速率常数随超电势呈非线性变化.而在高浓H2PtCl溶液中,沉积机理转变为H2PtCl6的吸附、瞬时成核及三维正圆锥形的生长模式.其晶核的垂直生长速率常数kPERP比水平生长速率常数kPARA大两个数量级以上.况且,logkPERP随超电势线性增加,而logkPARA则随超电势呈反S形变化的关系.相同超电势下,无论kPERP还是kPARA,均比稀H2PtCl6溶液中的二维层状生长速率常数大几个数量级.

关键词: 电沉积, 成核与生长, 铂在金基底上电沉积, 微电极

Abstract: Based on the Fleischmann's model of nucleation and crystal growth for electrodeposition combined with the Barradas-Bosco's adsorption-nucleation model for electrochemical phase formation, the chronoamperometry was well fitted for Pt deposition on polycrystalline Au micro disc electrodes (30 μm in diameter) in different H_(2)PtCl_(6) concentrations at different over-potentials. The initial stage of Pt deposition in dilute H_(2)PtCl_(6) could be interpreted by the model of H_(2)PtCl_(6 ) adsorption combined with instantaneous nucleation and two-dimensional cylindrical growth. The rate constant of the two-dimensional growth increased linearly with overpotential. Then the deposit grew layer by layer and the rate constant increased non-linearly with overpotential. In contrast to the situation in dilute solutions, Pt deposition in higher H_(2)PtCl_(6) concentrations was found to follow the mechanism of adsorption-instantaneous nucleation and three-dimensional cone growth.The rate constant of perpendicular growth (k_(perp)) appeared two orders of magnitude larger than that of parallel growth (k_(para))_( )and increased linearly with overpotential. However, the k_(para) increased with overpotential in S shape. Both k_(perp) or k_(para) in concentrated solutions were larger than the growth rate constant in dilute solutions.

Key words: Electrodeposition, Nucleation and crystal growth, Electrodeposition of Pt on Au , Microelectrodes

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