贵金属掺杂Ti/TiO_2电极的制备及其电催化性能研究

Study on Preparation and Electrocatalytic Activities of the Modified Ti/TiO_2 Electrodes by Doping Noble Metal

采用阳极氧化-阴极电沉积两步法:先在钛基体上用阳极氧化法制备多孔TiO2薄膜,接着在这层多孔状薄膜上采用阴极电沉积方法掺杂Pt,Ir来制备Ti/TiO2-Pt修饰电极和Ti/TiO2-Ir修饰电极.用XRD,SEM分析了掺杂前后的成分、相结构及表面形貌的变化,结果表明:Pt优先沉积在TiO2多孔中;与Pt不同,Ir没有表现出在TiO2孔中优先沉积的现象,出现这种现象的原因是这两种贵金属的电沉积电位相对于n-TiO2的平带电位不同.使用SIMS分析了在Ti/TiO2-(Pt/Ir)修饰电极中Ti,Pt,Ir的浓度分布,大致算出TiO2薄膜厚度为750nm左右.由极化曲线和阻抗谱结果得出:掺杂Pt,Ir明显改善了Ti/TiO2电极的电催化性能,且随着Pt沉积时间的增长,修饰电极在硫酸析氧反应中的电催化活性提高.

A two-step procedure was used for the preparation of the modified Ti/TiO2-Pt/Ir anodes： anodisation of the titanium substrate to form a microporous oxide film with subsequent doping Pt or Ix by cathodic deposition of an oxygen evolution reaction （OER） electrocatalyser. The characterization of the modified films was carried out by X-ray and SEM. In the case of Ti/TiO2-Pt, Pt is deposited preferentially within some of the micropores of the TiO2 film. Ir however, is distributed preferentially across the surface of the oxide film. The difference is thought to result from the position of the metal deposition potential with respect to the flat band potential of n-TiO2. Composition profile of different elements in thin film Ti/TiO2-（Pt/Ir） anodes was carded out by SIMS, and the TiO2 film thickness is obtained, ca. 750 rim. According to the resuits obtained by means of stationary current-potential curves and impedance spectra, Pt/Ir doping has improved the electrocatalytic activities.