中国科学院地球化学研究所机构知识库

The oxygen electrode reaction at the interface gold/yttria stabilized zirconia (YSZ) was investigated at moderate temperatures of 500 and 600℃ under ambient air condition, with emphasis put on the comparative analysis for effect of anodic and cathodic polarization on the electrode. Generally, at the temperature of 500℃, slow monotonous alterations of the absolute currents or potentials result from polarizations were observed, but the response curves exihibited obvious fluctuations at 600℃, which may be ascribed to the progressive transportation processes of the electro-active species in the electrode system. Due to the relatively weak adsorption ability of Au electrode interfaced with YSZ, the oxygen atoms induced by anodic polarization left toward the ambient air rapidly, which consequently led to the improved activity for oxidation reactions. However, while the electrode was under cathodic bias, the oxygen reduced mainly originated from the ambient air, and had to reach the reaction sites located at the two or three boundary interfaces through series of successive processes such as disassociation, adsorption and diffusion, which result in the low transporting efficiency of the active agencies beyond all doubt and consequently decreased activity for reduction reactions at the electrode system. The remarkable enhancement of electrode catalytic activity was only observed from the potentiostatic polarization experiments at 600℃ and with anodic polarization, perhaps due to the short polarization times and relatively low experiment temperatures.