HYDROGEN AND METHANE OXIDATION ON A GADOLINIA-DOPED CERIA ANODE ON A YSZ ELECTROLYTE

摘要

A mixed-conducting Ce_(0.6)Gd_(0.4)O_(1.8) (CG4) electrode was deposited on an yttria-stabilized zirconia (YSZ) electrolyte by applying Ni or YSZ scales as an anchoring layer. Complex impedance spectra of the CG4 electrode were obtained in H_2/H_2O and CH_4/H_2O atmospheres while altering the temperature, reagent partial pressures, gas flow rates and the applied potential. Impedance spectra were fitted using equivalent circuit models. After correction for concentration impedance, the two arcs in the impedance spectra were ascribed to the electrode reaction limitations. An actual polarization resistance, R_P, of 0.12 Ωcm~2 was measured at 1000°Cin H_2/H_2O=97/3. R_P was stable while decreasing P_(H_2), from 97 to 10 kPa under open-circuit conditions and increased with increasing P_(H_2O). At P_(H_2) < 10 kPa, R_P increased linearly with decreasing hydrogen partial pressure.