柠檬酸钠溶液中镍电结晶机制  

Mechanism of electrocrystallization of nickel in sodium citrate solution

作　　者：李超群[1] 李新海[1] 王志兴[1] 郭华军[1] 

机构地区：[1]中南大学冶金与环境学院,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2015年第8期2797-2803,共7页Journal of Central South University:Science and Technology

基　　金：国家重点基础研究发展计划(973计划)项目(2007CB613607)~~

摘　　要：采用循环伏安和计时电流法研究柠檬酸钠溶液中镍在玻碳电极上电结晶初期阶段的行为。研究结果表明:镍的电结晶经历了晶核形成过程且符合Scharitker-Hill三维成核/生长机制,在低过电位下,镍结晶按三维连续成核/生长方式进行;在高过电位下,镍结晶遵循瞬时成核/生长机制。沉积过电位增加,成核时间缩短,晶核数密度增大,生长速率增加,在2种成核/生长机制下镍离子的扩散系数分别为(1.63±0.48)×10-7和(1.07±0.09)×10-6cm2/s;柠檬酸钠对镍垂直于基体表面的生长速率有阻碍作用,增大硫酸镍质量浓度对生长速率有一定促进作用,但溶液中柠檬酸钠和硫酸镍质量浓度变化并不改变镍电结晶过程的成核/生长机制。The initial stage of electrocrystallization of nickel on vitreous carbon from sodium citrate solution was investigated by the cyclic voltammetry and chronoamperometry method. The results show that the deposition of nickel undergoes nucleation process and follows the mechanism of Scharitker-Hill three-dimensional nucleation/growth manner. Under lower overpotential, the electrocrystallization process of Ni from citrate bath in the initial stage follows the mechanism of three-dimensional progressive nucleation and growth manner. Under higher overpotential, the nucleation process of nickel ions follows the instantaneous nucleation and growth mechanism with three-dimensional. The nucleation time of nickel citrate solution system may gradually be shortened and the nuclear number densities and growth rate increase with the increase of overpotential. The diffusion coefficient D of the depositing nickel ions is（1.63±0.48）×10^-7 cm^2/s under the progressive nucleation and growth mechanism, and（1.07±0.09）×10^-6 cm^2/s under the instantaneous nucleation and growth mechanism, respectively. Sodium citrate may cause an inhibition of outward growth rate of Ni deposits, and increase of concentration of nickel sulfate may accelerate both nucleation and crystal growth. However, the changes in the concentration of sodium citrate and nickel sulfate do not change nucleation/growth mechanism of nickel electrocrystallization.

关 键 词：电结晶 镍沉积 柠檬酸盐溶液 玻碳电极 机制 

分 类 号：TG174.44[金属学及工艺—金属表面处理] TQ153.12[金属学及工艺—金属学]