ChCl-EG低共熔溶剂体系中镍沉积的电化学行为研究

Electrochemical Behavior of Nickel Electroplating Process in ChCl-EG Eutectic Solvents

目的研究镍在低共熔溶剂体系中的电沉积、电化学行为及形核方式。方法使用循环伏安法和计时电流法,研究在氯化胆碱-乙二醇(ChCl-EG)低共熔溶剂体系中镍沉积的电化学行为及其形核理论。采用SEM测试手段对镍电沉积层的微观形貌进行观察和分析,同时采用EDS分析镍镀层的元素组成。结果 ChCl-EG低共熔溶剂的电化学窗口为2.63 V,镍在ChCl-EG低共熔溶剂体系中的氧化、还原电位分别为0.79 V和-0.34 V。不同扫描速度的循环伏安曲线表明,在扫速为10~50 mV/s时,Ep与v无关,呈现出可逆反应的特性;而当扫速增加到50~90 mV/s时,Ep随v的增加而呈现负移的趋势,符合不可逆反应的特性。可以判断镍(Ⅱ)在ChCl-EG低共熔溶剂中属于准可逆反应。在"电流滞环"-1.00^-1.08V下测定计时电流曲线,通过拟合计时电流曲线与理论模型对比发现,镍(Ⅱ)在ChCl-EG体系中的电结晶过程符合Scharifker-Hill三维形核模型。镍电沉积层在铜基体上分布均匀,镀层中只含有镍元素。结论镍(Ⅱ)在氯化胆碱-乙二醇低共熔溶剂中的电沉积过程是准可逆反应且形核机制为三维瞬时成核,通过ChCl-EG低共熔溶剂体系可以得到纯度高并且分布均匀的镍镀层,且镍镀层的颗粒尺寸为22.1 nm。

The work aims to study the electroc-deposition,electrochemical behaviors and nucleation theory of nickel in eutectic solvent system.Cyclic voltammetry and chronoamperometry were used to study the electrochemical behaviors and nucleation theory of nickel deposition in Choline Chloride-Ethylene Glycol(ChCl-EG)eutectic solvent system.Scanning electron microscopy(SEM)was used to observe and analyze the micro-morphology of the nickel electrodeposited layer and EDS was adopted to analyze the elemental composition.The electrochemical window of ChCl-EG eutectic solvent was 2.63 V and the redox potential of nickel in ChCl-EG eutectic solvent system was respectively 0.79 V and?0.34 V.The cyclic voltammetry curves of different scanning velocities showed that when the scanning velocity was from 10 mV/s to 50 mV/s,Ep was independent of v and exhibited the characteristics of reversible reaction.When the scanning speed was increased from 50 mV/s to 90 mV/s,the trend of negative shift of Ep with the increase of scanning velocity v was observed and conformed to the characteristics of irreversible reaction.Nickel(Ⅱ)was a quasi-reversible reaction in ChCl-EG eutectic solvents.The chronoelectric curves were measured from-1.00 V to-1.08 V at"current hysteresis".Through the comparison of fitting chronoelectric curves and theoretical model,the electrocrystallization process of nickel(Ⅱ)in ChCl-EG system accorded with the Scharifker-Hill three-dimensional nucleation model by fitting the chronoelectric curve and comparing with the theoretical model.Nickel electrodeposit was distributed uniformly on copper substrate,and only nickel element was found in the coating.The electrodepositing process of nickel(II)in Choline Chloride-Ethylene Glycol(ChCl-EG)eutectic solvent system is quasi-reversible and the nucleation mechanism is the three dimensional transient nucleation.Through the Choline Chloride-Ethylene Glycol(ChCl-EG)eutectic solvent system,the nickel coating with high purity and uniform distribution can be obtained and the nickel coating has a particle size of 22.1 nm.