Abstract
The cathodic process of the Pt(Ga 2O 3)/YSZ electrode in O 2, N 2 gas mixtures with and without NO is studied by electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) in a wide range of gas composition at temperature range 450–800 °C in order to investigate its electrocatalytic activity for the electrochemical reduction of oxygen and NO, respectively. The results of the impedance spectra and j c– η c polarisation curves suggest different cathodic mechanisms at two temperature regions. For temperatures <650 °C, the cathodic O 2 reduction occurs in two consecutive one-electron transfer steps. At ϑ>650 °C, O 2 reduction follows a two-electron transfer step. The electrocatalytic activity of the Pt/YSZ electrode is enhanced due to presence of NO in the gas mixture leading to a decrease of the apparent activation energy and an increase of the exchange current density. The admixture of Ga 2O 3 to Pt/YSZ shows an inhibitor effect on the cathodic O 2 reduction at low temperature. Aside from this, it has decreased the electrocatalytic efficiency of the Pt/YSZ electrode for cathodic NO reduction.
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