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CHARACTERISTIC CURRENT DENSITY FOR ELECTRODEPOSITION OF ZINC AND ZINC ALLOYS.

锌和锌合金电沉积的特征电流密度。

基本信息

批准号：
08455348
负责人：
FUKUSHIMA Hisaaki
金额：
$ 0.64万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455348/
关键词：
Critical current density Zinc Cadmium Manganese Hydrogen Hydroxide Catalysis Electrodeposition

项目摘要

The minimum hydrogen overpotential on Al and Cd cathodes was reduced by the catalytic SCN^- ions in the solutions of low pH 1 and 2. The change in the magnitude of minimum hydrogen overpotential was less dependent on the concentration of SCN^- ions in Al cathode than Cd cathode. Moreover, the minimum hydrogen overpotential was not affected by the catalyst at higher pH 3,4 and 5 because the diffusion overpotential of hydrogen ions was predominant than other factors.The critical current density of Zn was greatly increased in the solutions of lower pH.This was in good agreement with previously predicted Zn deposition mechanism. Since the pH buffering capacity of the sulfate solution increases considerably with decreasing pH of the solution below 2, larger hydrogen evolution rate is required to achieve the critical pH for Zn hydroxide formation. Therefore the higher critical current density was observed in the solutions of lower pH.The critical current density was slightly increased in the SCN^- ion-containing solutions at low pH of 1 due to the reduction of minimum hydrogen overpotential by SCN^- ions and the current density was not changed by the catalyst in the solutions of high pHs probably because that the catalytic effect of SCN^- ions disappeared in the presence of Zn ions or Zn hydroxide.The critical current density was increased with increasing the concentration of Cd ions in the solution, because the initial cathode surface was replaced by deposited Cd with high hydrogen over-potential and the hydrogen evolution rate was greatly reduced by Cd deposition at high current efficiency and the current density was not affected by the presence of less noble Mn than Zn in the solutions because the deposition potential of Mn was hardly attained at the equilibrium potential of Zn.

在低pH 1和2的溶液中，催化SCN^-离子降低了Al和Cd阴极上的最小氢过电位。Al阴极中SCN^-离子浓度对最小氢过电位的影响小于Cd阴极中SCN^-离子浓度对最小氢过电位的影响。在较高pH值（3、4、5）时，由于氢离子的扩散过电位起主导作用，催化剂对最小氢过电位的影响不大，而在较低pH值时，Zn的临界电流密度大大提高，这与前人预测的Zn沉积机理相一致.由于硫酸盐溶液的pH缓冲能力随着溶液的pH降低到2以下而显著增加，因此需要更大的析氢速率来实现氢氧化锌形成的临界pH。在低pH（1）的含SCN^-离子的溶液中，由于SCN^-离子降低了最小氢过电位，临界电流密度略有增加，而在高pH溶液中，电流密度不受催化剂的影响，这可能是由于SCN^-离子的催化作用随着溶液中Cd离子浓度的增加，临界电流密度增大，因为最初的阴极表面被沉积的Cd所取代，在高电流效率下，Cd沉积大大降低了析氢速率，并且电流密度不受稀有Mn的影响，由于Mn的沉积电位很难达到Zn的平衡电位，