Nakanishi Shuji, Sakai Sho-ichiro, Nishimura Kensaku, Nakato Yoshihiro
Division of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
J Phys Chem B. 2005 Oct 13;109(40):18846-51. doi: 10.1021/jp0513871.
Electrochemical deposition of copper (Cu) from aqueous acidic Cu2+ solutions with o-phenanthroline (o-phen) shows both potential and current oscillations, together with a (partially hidden) N-shaped negative differential resistance (N-NDR), indicating that the oscillations are classified into hidden N-NDR (or HN-NDR) oscillations. The color and the surface morphology of Cu deposits oscillate in synchronization with the potential and current oscillations. Microscopic inspection has shown that dense round Cu leaflets, which look gray, grow in the positive side of the potential oscillation or in the high-current state of the current oscillation, whereas thin Cu leaflets, which look black, grow in the opposite-side stages of the potential and current oscillations, thus finally resulting in a layered Cu deposit with the layer thickness of about 5 microm. The appearance of the NDR is explained to be due to adsorption of the reduced form of a [Cu(II)(o-phen)2]2+ complex, which suppresses the Cu electrodeposition. The increase in the effective electrode surface area by growth of thin Cu leaflets, on the other hand, causes a current increase that can hide the NDR. This NDR-hiding mechanism is of a new type and the present oscillation is regarded as a new-type of HN-NDR oscillator.
在含有邻菲罗啉（o-phen）的酸性铜离子水溶液中进行铜（Cu）的电化学沉积时，会出现电位和电流振荡，以及（部分隐藏的）N 形负微分电阻（N-NDR），这表明该振荡可归类为隐藏 N-NDR（或 HN-NDR）振荡。铜沉积物的颜色和表面形态与电位和电流振荡同步振荡。显微镜检查表明，看起来呈灰色的致密圆形铜薄片在电位振荡的正向或电流振荡的高电流状态下生长，而看起来呈黑色的薄铜薄片则在电位和电流振荡的相反阶段生长，最终形成层厚约为 5 微米的层状铜沉积物。NDR 的出现被解释为是由于[Cu(II)(o-phen)2]2+络合物还原形式的吸附，它抑制了铜的电沉积。另一方面，薄铜薄片的生长导致有效电极表面积增加，从而引起电流增加，这可能会掩盖 NDR。这种 NDR 隐藏机制是一种新型机制，目前的振荡被视为一种新型的 HN-NDR 振荡器。
