纳米-Al2O3颗粒对镍电结晶初期阶段的影响

利用循环伏安(CV)、计时安培(CA)和电化学阻抗(EIS)研究了纳米Al2O3颗粒在不同电位(vs.SCE)下对Ni自硫酸盐镀液在铜基体上电沉积的影响。结果表明,Ni-Al2O3体系共沉积的起始电位为:–740mV左右;在不同的电位下,纳米-Al2O3颗粒对镍沉积过程的影响有所差别;在电位–740～–830mV范围,与纯Ni沉积相比较,Ni-Al2O3体系沉积的峰电流所对应的孕育期tm明显缩短,反映Al2O3颗粒在阴极表面有利于镍沉积成核,且促进了电结晶成核。Al2O3颗粒吸附在阴极表面可能会阻碍部分离子电荷放电和物质传输过程,尤其在电位–250～–650mV范围,致使Ni-Al2O3体系沉积阻抗增加。在较高的过电位下,Al2O3颗粒的促进作用有所减弱,许多颗粒堆积在电极表面上还可能减小Ni-Al2O3沉积的还原反应电流。在电位–890mV,Ni-Al2O3体系电沉积初期阶段的成核过程基本遵循三维的Scharifker-Hill瞬时成核模式。

Influence of Nano-Al2O3 Particles on Nickel Electrocry- stallization at Initial Stage

The influence of nano-Al_2O_3 particles on nickel deposition on copper matrix from acid sulphate solution was studied under various potentials (vs. SCE) by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The results show that the beginning potential of Ni-Al_2O_3 co-deposition is at -740 mV or so. The effect of nano-Al_2O_3 particles on nickel deposition process may be different under various potentials. In the potentials range from -740 to -830 mV, Al_2O_3 particles on cathode surface may be favorable for nickel deposition nucleation and promote electron crystallization nucleation because the induction period tm corresponding to the peak current of Ni-Al_2O_3 co-deposition is apparently shortened, compared with that of pure Ni deposition. However, Al_2O_3 particles adsorbed on cathode surface may obstruct electric discharge of partial ions and mass transmission process, resulting in the impedance increment of Ni-Al_2O_3 co-deposition, especially in the potentials range from -250 to -650 mV. The favorable effect of Al_2O_3 particles weaken in the range of high over potential, and the particles accumulated on electrode surface will decrease the reduction current of Ni-Al_2O_3 deposition. At the potential -890 mV, the nucleation process of Ni-Al_2O_3 co-deposition at initial stage follows the instantaneous model of Scharifker-Hill with three-dimensional fashion.