Rate determining steps of fuel oxidation over CeO2 impregnated Ni-YSZ in H2+ H2O + CO + CO2 ambient

Polarization resistance of the Ni-Zr0.84Y0.16O1.92 anode impregnated with cerium oxide in H2 + H2O + CO + CO2 + Ar gas mixtures of different composition was studied at temperatures of 700–950 °C by means of EIS and subsequent DRT and NLLS analysis of EIS spectra. The electrochemical activity of the anode in the H2 + H2O + CO + CO2 + Ar was found to be defined basically by the hydrogen-containing components (H2 and H2O). The EIS spectra analysis revealed that the anode polarization resistance is determined by three processes, registered at high-, middle- and low-frequencies, respectively. The high-frequency resistance had an activation energy of about −0.93 eV and it did not depend on the gas mixture composition. Both the middle-frequency resistance (activation energy of about −1.04 eV) and the low-frequency resistance (0.31 eV) depended on the gas atmosphere composition. Suggestions about the nature of the rate-determined steps were proposed.