Activity for the methane oxidation by the alloying effect of 3d-transition metal solid solution

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The solid-oxide-fuel-cell performance using a cermet-type anode, which consists of the Ni-Co solid-solution alloy particles dispersed in the matrix of samaria-doped ceria (SDC) grains or that of yttria-stabilized zirconia (YSZ) grains, has been investigated. The anodic polarization resistance of the Ni_<0.5>Co_<0.5>-SDC (or YSZ) anode was low for H_2 and CH_4 using an SDC electrolyte disk or a scandia-stabilized zirconia (ScSZ) electrolyte disk. The microstructural characterization of these cermet anodes revealed a proof of an enhancement effect on the electrochemical oxidation of CH_4. In the case of using the SDC electrolyte, the oxide ions supplied through the SDC electrolyte contribute to the oxidation of methane even under the open circuit condition, which is specific to the mixed ionic electronic conduction of SDC. It was found that the redox reaction occurring at surface of ceria-based oxides enhances the oxidation rate of methane with the support of Ni_<0.5>Co_<0.5> particles dispersed among the electrolyte grains.