NaCl-KCl-IrCl3熔盐体系中电沉积Ir层的机理

来源期刊:中国有色金属学报(英文版)2012年第11期

论文作者:钱建刚 赵 天

文章页码:2855 - 2862

关键词:Ir;NaCl-KCl熔盐;NaCl-KCl-IrCl3熔盐;电沉积;还原机理;电极反应;活化能;微孔

Key words:Ir; NaCl-KCl molten salt; NaCl-KCl-IrCl3 molten salt; electrodeposition; reduction mechanism; electrode reaction; activation energy; micro-pores

摘    要:在NaCl-KCl-IrCl3熔盐体系中利用循环伏安法和计时电位法研究Ir的沉积机理并通过恒电位法在Pt基体上制备出Ir层。利用扫描电子、显微镜(SEM)能谱仪(EDS)和X射线衍射仪(XRD)对Ir层的表面形貌和成分进行分析。结果表明:在NaCl-KCl-IrCl3熔盐体系中Ir的电沉积过程为Ir3+获得3个电子一步沉积为Ir,并且Ir(Ⅲ) →Ir(0) 的电极反应过程为可逆扩散控制过程;在1063、1113、1143和1183 K下Ir(Ⅲ)离子的扩散系数分别为0.60×10-4、1.23×10-4、2.77×10-4和4.40×10-4 cm2∕s,Ir(Ⅲ)在NaCl-KCl-IrCl3熔盐体系中电极反应的活化能Ea=162.6 1kJ/mol;沉积电位对所获得的Ir层的形貌有较大影响,其中在峰值电位下所获得的Ir层较厚;熔盐温度对电沉积Ir层的形貌也有较大影响,在较低熔盐温度下获得的Ir层较薄,较高熔盐温度获得的Ir层的孔隙较多。

Abstract: The reduction mechanism of Ir in the NaCl-KCl-IrCl3 molten salt was investigated by cyclic voltammetry and chronopotentiometry, and Ir film was deposited effectively on platinum in potentiostatic mode. The morphology and constitution of Ir film were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). It is found that the reduction mechanism of Ir(III) is a three-electron step and electro reaction is a reversible diffusion controlled process; the diffusion coefficients of Ir(III) at 1083, 1113, 1143 and 1183 K are 1.56×10-4, 2.23×10-4, 2.77×10-4 and 4.40×10-4 cm2/s, respectively, while the activation energy of the electrode reaction is 102.95 kJ/mol. The compacted Ir film reveals that the applied potential greatly affects the deposition of Ir, the thickness of Ir film deposited at the potential of reduction peak is the highest, the temperature of the molten salt also exerts an influence on deposition, the film formed at a lower temperature is thinner, but more micropores would occur on film when the temperature went too high.

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