Kinetics analysis of Ni-TiO₂ composite system during initial stages of electro-crystallization

来源期刊：中南大学学报(英文版)2010年第3期

论文作者：胡炜 谭澄宇 崔航 刘宇 郑子樵

文章页码：460 - 466

Key words：Ni-TiO₂ system; kinetics; electro-crystallization; cyclic voltammetry; electrochemical impedance spectroscopy

Abstract: The initial stage of Ni-TiO₂ composite system electrodeposition on glassy carbon electrode from an acidic solution of nickel sulfate was investigated using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). Analysis of current density-time transients was performed using the nonlinear fitting procedure and electrochemical impedance spectroscopy was simulated by Z-view software. Besides, the surface morphology of Ni-TiO₂ co-deposition at the initial stage was observed by scanning electron microscopy (SEM). The results show that, in the case of low overpotential (-790 mV vs SCE), the presence of TiO₂ particles in the plating bath makes the nucleation relaxation time t_max decreased clearly. Meanwhile, the electro-crystallization of Ni-TiO₂ system follows a Scharifker-Hills (SH) progressive nucleation/growth mechanism. While in the case of higher overpotential, the presence of the TiO₂ particles in solution makes the nucleation relaxation time t_max increased. At -850 mV (vs SCE), the co-deposition of Ni-TiO₂ system meets SH instantaneous nucleation/growth mechanism. The results of impedance spectra show that the appearance of the characteristic inductive loops represents the nucleation/growth of nickel and the presence of TiO₂ particles reduces the charge transfer resistance of solution. The SEM observation confirms that TiO₂ particles can be considered as favorable sites for nickel nucleating.

基金信息：the Project of National Defense of China