温度对PbO_2电沉积形核生长过程的影响研究

Effects of Temperature on the Nucleation and Growth Mechanism of PbO_2 Electrodeposition

为探讨温度对PbO_2电沉积形核生长过程的影响,在25oC、35oC、45oC、55oC、65oC使用电化学工作站测试了PbO_2在玻碳电极上沉积过程的循环伏安曲线、计时电位曲线及计时电流曲线,并对不同温度下电沉积的PbO_2镀层进行了SEM和XRD分析.结果表明,在不同温度下PbO_2均经历了成核和核生长过程.温度的升高未改变PbO_2电沉积三维连续成核的模式,但降低了沉积过程溶液阻力,对成核和晶体生长速率均有促进作用.在晶核密度达到饱和晶核密度以前,以促进成核速率为主,使PbO_2颗粒尺寸减小.电沉积后期达到饱和晶核密度后,以促进晶体生长速率为主,不利于形成细小PbO_2颗粒.高温使析氧速率提高,能耗增大.由实验结果得出,在55oC时得到的PbO_2镀层粒径最小.

In order to investigate the effects of temperature on the nucleation and growth of lead dioxide （PbO2）, the in situ electrochemical depositions of PbO2 were carried out on the glassy carbon electrode at different temperatures, namely, 25 ℃, 35℃, 45℃, 55℃, and 65℃. The cyclic voltammetric curves, the time-current and the time-potential curves, SEM images and XRD patterns of the PbO2 coatings deposited at different temperatures were obtained. The results showed that the PbO2 underwent nucleation and grew at different temperatures. The 3D continuous nucleation mode of PbO2 electrodeposition remained unchanged with the in- crease of temperature. However, the solution resistance during the deposition process was decreased. The nucleation rate and the crystal growth rate were both promoted by the increase of temperature. Before reaching the saturated nucleation density, the nucleation rate was accelerated, and the size of PbO2 particles was reduced. During the later stage of the deposition, once the saturated nucleation density was attained, the nucleation rate became prodimnant, which adversely influenced the crystal growth rate, and the coating was not conductive to the formation of small PbO2 particles. High temperature enhanced the oxygen evolution rate and in- creased the energy consumption. The average particle size of PbO2 obtained at 55℃ was the smallest one among the five temperatures tested.