柠檬酸钠体系中Ni・Fe合金的电沉积行为

采用循环伏安曲线、电化学阻抗谱、计时电流曲线等方法对柠檬酸钠体系中Ni-Fe合金的电沉积行为进行了研究。结果表明:柠檬酸钠体系中Ni-Fe合金电沉积是一个受扩散控制的不可逆过程。随着电位的增大,电沉积依次经历了电化学活化阶段、电结晶成核阶段、动力学-扩散混合控制阶段和扩散控制阶段。阴极附近未被及时消耗的FeOH+会覆盖在电极表面,阻碍金属离子扩散到电极表面放电,使电化学阻抗谱低频端存在阻挡层扩散阻抗特征。随着电位的增大,Ni-Fe合金的成核速率逐渐加快。Ni-Fe合金的成核机制在低电位下表现为连续成核,在高电位下表现为瞬时成核。

Electrodeposition Behavior of Ni-Fe Alloy in Sodium Citrate Bath System

Electrodeposition behavior of Ni-Fe alloy in sodium citrate bath system was investigated using cyclic voltammetry curve,electrochemical impedance spectroscopy and chronoamperometry curve.The results showed that electrodeposition of Ni-Fe in sodium citrate bath system was an irreversible process controlled by diffusion.With the increase o cathodic potential,the electrodeposition went through the stages of electrochemical activation,electrocrystallization nucleation,dynamics-diffusion mixed control and diffusion control.FeOH+,which was not consumed in time near the cathode,will cover the electrode surface and prevent metal ions diffusing to the electrode surface to discharge,so that there was a barrier layer diffusion impedance characteristic at the low frequency end of the impedance spectrum.With the increase of cathodic potential,the nucleation rate of Ni-Fe alloy increased gradually.The nucleation mechanism of Ni-Fe alloy was continuous nucleation at low potential and transient nucleation at high potential.