In situ formation of LaNi0.6Fe0.4O3−δ-carbon nanotube hybrids as anodes for direct-methane solid oxide fuel cells

Here we report the use of LaNi0.6Fe0.4O3−δ/carbon nanotube (LNF/CNT) hybrids as novel and robust anode catalysts that are in situ fabricated by exposure of nano-scale LNF perovskite oxide catalysts to slightly humidified methane. TEM observations confirm the formation of CNTs with the inner diameter and the wall thickness both at ≈15 nm. Combined XRD and EDX analyses show that LNF oxides decompose into a mixture of La2O3, FeNi3 alloy and LaFeO3, where FeNi3 alloy particles have an average diameter of 45 nm, largely exist outside of these CNTs and are surrounded by nano-scale La2O3 and LaFeO3 oxides. The LNF/CNT hybrids exhibit superior catalytic activities for methane oxidation reactions, yielding low anode polarization resistances of 0.22 Ω cm2 at 800 °C and 0.44 Ω cm2 at 750 °C. Impregnated fuel cells with such hybrid anodes display stable and excellent power densities in methane fuels. e.g., 1.00 W cm−2 at 800 °C and 0.73 W cm−2 at 750 °C.