GDC-Impregnated (La[sub 0.75]Sr[sub 0.25])(Cr[sub 0.5]Mn[sub 0.5])O[sub 3] Anodes for Direct Utilization of Methane in Solid Oxide Fuel Cells

Gd-doped ceria (GDC)-impregnated ( La 0.75 Sr 0.25 ) ( Cr 0.5 Mn 0.5 ) O 3 (LSCM) is investigated as an alternative Ni-free anode for the direct utilization of methane in solid oxide fuel cells. Impregnation of submicrometer and ionic conducting GDC greatly improves the electrocatalytic activity of the LSCM anodes for the oxidation reaction in weakly humidified (3% H 2 O ) methane. At 800 ° C , electrode polarization resistance for the reaction in wet C H 4 is 0.44 Ω cm 2 on a 4.0 mg cm − 2 GDC-impregnated LSCM anode. In comparison, the electrode polarization resistance is 11.4 and 8.1 Ω cm 2 on a pure LSCM and a LSCM ( 50 wt % ) /yttria-stabilized zirconia (YSZ) ( 50 wt % ) composite anode, respectively, under the same testing conditions. The polarization performance of GDC-impregnated LSCM is also substantially higher than that of the pure LSCM and LSCM/YSZ composite anodes. Based on the results, a mechanism involving the dry reforming of methane, followed by the electrochemical oxidation of the dry reforming products is proposed for the methane oxidation on Ni-free mixed ionic and electronic conductors such as LSCM. Impregnation of nanosized GDC greatly enhances the catalytic as well as electrochemical activities for the dry reforming of methane and for the electrochemical oxidation reactions of the dry reforming products.