金属电沉积噪声能量与镀层沉积机制和结构的关系研究

The aim of this project is the first attempt to study the electroplating mechanism in the view of energy. During the electroplating processes of zinc, Ni and Ag onto Cu and Ag substrates, the evolution features of the electrochemical noise energy with the electro-crystallization behavior, the deposit’s structure and surface energy, the energy of the preferential orientation crystal face and the depositing reaction rate etc, will be first investigated by using EN, SECM, XRD and so on. Then, their mutual relationship will be modeled and elucidated theoretically. Moreover, an energy criterion / judgment will be obtained to differentiate the rate-determining step (such as diffusion, mixed of activation control), and the relationship between “the relative energy for crystallite nucleation and growth” and the “crystallite nucleation rate and growth rate" will be studied in details. This project can not only reveal the internal relations of the electrochemical reaction active energy with the depositing rate and the deposit structure, solve the academic problem left over by history that, so far, it is unable to separate the grain nucleation rate and growth rate during metal depositing process, but also can expand the electrochemical theory and the principle of electrochemical technique. Therefore, this project has important theoretical value and practical significance.

本项目在国内外率先开展金属电沉积机制的能量学研究。采用EN、SECM和XRD等深入研究Zn、Ni、Ag等电沉积过程中的电化学噪声能量与电沉积机制、镀层结构、镀层表面能和费米能级、镀层择优取向生长晶面的晶面能和电沉积反应速率等的演化规律及其相互关系，建立并求解相关理论模型；获得判断电沉积过程的受限条件（扩散、混合和活化控制等）的能量判据。在上述研究的基础上，明晰EN中的“晶粒的成核相对能量和生长相对能量”与“晶粒的成核速率和生长速率”之间的关系。本项目研究不仅可揭示电化学噪声能量与电沉积速率和镀层结构等之间的内在联系、解决目前学术界“无法分离晶粒的成核速率与生长速率的相对大小”等历史遗留问题，而且可以拓展电化学理论和电化学技术原理。因此，具有重要的理论价值和实际意义。

电化学噪声(Electrochemical noise, EN)是指电化学动力系统演化过程中,其电学状态参量(如：电极电位、外测电流密度等)的随机非平衡波动现象。本项目采用CV、EN和CHR等电化学技术并辅以SEM和XRD等材料表征手段研究了Ni及Zn在高纯Cu和玻碳电极上的电沉积过程。探明了“电沉积过程中的电化学噪声能量ED、晶粒的成核和生长相对能量”和“（相应/对应）镀层的沉积速率、结构、表面能、镀层择优取向生长和晶粒大小等”的演化规律及其相互关系；研究了“电沉积初期的EN、晶粒的成核和生长相对能量”与基体晶面或表面能之间的关系。取得了以下主要研究成果：（1）创新性地提出了表征电极过程的新参数——电化学噪声能量ED，发现ED主要反应了镀层的初始单层“成核/生长”过程中电极体系所获得的能量、刻画了镀层初始单层的成核/生长难易程度，ED越大则电极过程的电荷转移难度越大；（2）不同的镀层初始成核/生长机制的ED值有较大的差异；（3）EDP的高阶晶胞能量主要反应了初始单层的成核信息、高阶晶胞能量越高则成核难度越大，而其低阶晶胞能量主要反应了初始单层的生长信息、低阶晶胞的能量越高则生长越难；（4）提出了镀层量均粒径(d_(D_K ) ) ̅的概念，并基于镀层晶面的功函数提出了镀层能量E_x的概念。发现噪声能量ED与E_x×(d_(D_K ) ) ̅ 基本具有反平行性变化规律；由于E_x变化不大，所以噪声能量ED与量均粒径(d_(D_K ) ) ̅ 基本具有反平行性变化规律。