Study on Charge Transfer Reactions in Electrodeposition

(1)电沉积中Helmholtz层中的电荷转移反应研究用小交流电密度下的电化学阻抗谱研究了氨基磺酸镍电解液中(110)单晶镍表面的电化学反应。结果表明，反应阻抗与交流调制频率呈幂函数关系，反应电阻和反应电容的两个指数与均相荷移反应模型的预测值一致。此外，奈奎斯特图显示没有感应回路。本文给出了电感应环存在的条件，认为Ni^&lt；2+&gt；离子的电晶化可能发生在慢反应步骤Ni^&lt；2+&gt；+e^-→Ni^+&lt；abs&gt；；在快反应步骤Ni^+&lt；abs&gt；+e^-→Ni。(2)电沉积亥姆霍兹层中的暂态过程。本文介绍了一种研究电极反应…动力学的方法在离子扩散、电荷转移反应和双电层荷电过程三个暂态电化学过程解析解的基础上，进一步推广了S的观点。在工作电极上施加多脉冲电流，并记录电位。测得的电势-时间曲线与解析解预测的结果一致。(3)电沉积过程中的表面形核和生长。在固定电流密度和纳秒上升时间下，测量了氨基磺酸镍中单晶镍电极表面生长的电压-时间曲线。双电极体系的暂态电压-时间曲线呈现出三个连续的区域，分别对应于镍离子的两步电化学反应还原、成核生长等晶化过程和稳态表面生长过程。实验测得的电压-时间曲线与本文提出的唯象方程的计算结果吻合较好。较少

(1)Charge transfer reactions in the Helmholtz layer in electrodepositionElectrochemical impedance spectroscopy measurements under a small alternating current density were performed to make investigations into electrochemical reactions on (110) single-crystalline nickel surfaces in nickel sulfamate electrolyte. The reaction impedance shows a power law of the ac modulation frequency and two exponents for the reaction resistance and reaction capacitance are found to agree with the values predicted by a homogeneous charge-transfer reaction model. In addition, the Nyquist diagrams exhibit the absence of inductive loops. A condition for the existence of inductive loops derived in this study suggests that the electrocrystallization of Ni^<2+> ions may take place in the slow reaction step Ni^<2+>+e^-→Ni^+_<abs> and in the fast reaction step Ni^+_<abs>+e^-→Ni.(2)Transient process in the Helmholtz layer in electrodepositionA method is described for the study of the kinetics of electrode reaction … More s on the basis of analytical solutions of three transient electrochemical processes comprising the diffusion of ions, charge-transfer reactions and a charging process of an electrochemical double-layer. Multi-pulse currents are applied to a working electrode and the potentials are recorded. The measured potential-time curves agree with those predicted by the analytical solution. The kinetic constant, exchange current density and double-layer capacitance are determined from the measured potential-time curves using the analytical solution.(3)Surface nucleation and growth in electrodepositionVoltage-time curves in surface growth on single crystalline nickel electrodes in nickel sulfamate have been measured under a fixed current density with a nanosecond rise-time. The transient voltage-time curves in a two-electrode system exhibit three continuous regions that correspond to the reduction of nickel ions by two-step electrochemical reactions, the crystallization process such as nucleation and growth, and steady state surface growth. The measured voltage-time curves are well consistent with the calculation results predicted by phenomenological equations proposed in this study. Less