酸性硫酸盐电解液中沉积Ni-W合金的动力学

Kinetics of Ni-W Alloy Electro-deposition in Acidic Sulphate Electrolyte

在酸性硫酸盐镀液中,采用循环伏安曲线和计时安培曲线等电化学方法结合Scharifker-Hills模型对Ni-W合金镀层的沉积过程进行了动力学研究。结果表明,Ni-W合金循环伏安曲线存在电流环,在玻碳电极上发生成核过程;电解液中WO_4^(2-)浓度增加会促进镀层晶体形核过程。Scharifker-Hills模型分析结果表明,纯镍在玻碳电极上表现为三维生长的瞬时成核机理。在电解液中加入WO_4^(2-)进行Ni-W合金共沉积时,在较小的过电位下表现为连续形核机制,在较大的过电位下与连续形核曲线略有偏离,表现为连续形核和瞬时形核共存的形核机制。

Cyclic voltammetry curves （CV） and chronoamperometry（CA） in coniunction with the 5charlttcer-Flms model （SH） were used to study the initial stage of Ni-W alloy electro-deposition. The results indicated that the electro-deposition of the Ni-W alloy on glassy carbon electrode consisted of nucleation and growth. The crystal nucleation of plating improved as the concentration of WO42- increased and its reduction intermediate products could be considered as favorable sites of the Ni-W alloy. According to the analysis of Scharifker-Hills model, the pure Ni nucleation process follows a three dimension-instantaneous mechanism, while the Ni-W alloy is a progressive nucleation mechanism at a lower over-potential, which slightly deviats from the progressive nucleation curve at higher over-poterltial and shows a instantaneous nucleation mechanism.