Studies on the Deposition and Characteristics of Ruthenium Oxide by Electrochemical Methods

• Main Authors: Kao Wei Xin, 高維欣
• Other Authors: J.J. Jow
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/41706267235751795346

碩士 === 國立高雄應用科技大學 === 化學工程系碩士班 === 92 === Abstracts The growth of Ruthenium oxides on Ti substrates in RuCl3.3H2O and HCl aqueous solution by cyclic voltammetric (CV) methods and constant potential deposition are studied in this work. Rotating electrode technology, SEM,XPS and EIS measurements are performed to investigate the growth mechanisms and the properties of ruthenium oxide deposition. The results of rotating electrode study show that the CV deposition of Ruthenium oxides via anodic and cathodic cycling in the potential range of —0.2 to 1.1 V vs. SCE are mainly contributed by the anodic oxidation of Ru(III) ions, while that via the cathodic reduction of Ru(III) ions are not apparent. The limiting current of the cathodic polarization behaviors on the rotating electrode is in accordance with the Levich’s equation and the diffusivity (D) values of Ru(III) ions calculated accordingly are in the range 1.05*10-5 to 2.56*10-6cm2/sec. D values decrease with the increase of the pH, RuCl3 concentration and aging time of the solution, about 25-40% and 30- 60% decrease of the D values are found after 24 and 144 hours storage of the solution respectively. The results of XPS analysis show that the ruthenium oxides via cathodic reactions lead to higher Ru-O-Ru and lower H2O composition, and a more stable structure than that via anodic reactions. The SEM photographs show crack phenomena appears in the deposits via CV deposition, while smooth deposits are obtained via cathodic deposition. The EIS study shows that The impedance of RuOx electrode decreases apparently after annealing at temperature higher than 200℃ due to the crystallization of the deposition. The redox reversibility of CV deposited RuOx electrode is better at higher electrode potential( e.g. 1.0 V vs. SCE) than that at lower electrode potential(e.g. 0V vs. SCE), while that are about equal in the potential range 0 - 1.0 V for cathodically prepared RuOx electrodes. It indicates the properties of ruthenium oxide electrodes are significantly dependent on the electrochemical deposition conditions. The optimum H2SO4 concentration for minimum equivalent series resistance (ESR) for RuOx electrochemical capacitor obtained is 4M.