FUEL 59

Pt-Ir/TiC catalyst was investigated by electrochemical impedance spectroscopy in acid medium. The results indicate that the Pt-Ir/TiC catalyst electrode at various potentials shows different impedance behaviors. The charge transfer resistance, constant phase element and the two Nernstian impedances gradually decrease with polarization potential increasing. There is evident charge transfer process at the potentials of 0.70 V~ 0.90 V. In comparison with the corresponding mixture catalyst of Pt and Ir at 0.8 V, Pt-Ir supported on the TiC can significantly improve the electrode performance for oxygen evolution. According to the analysis of equivalent fitting electrical circuit at 0.8 V, the process of oxygen evolution reaction at the Pt-Ir/TiC catalyst electrode is mainly composed of the charge transfer reaction and Nernstian diffusion processes.

Keywords: Electrochemical impedance spectroscopy; Pt-Ir/TiC catalyst; Equivalent fitting electrical circuit; Charge transfer; Nernstian diffusion