Direct-methane solid oxide fuel cells with hierarchically porous Ni-based anode deposited with nanocatalyst layer

Current development of solid oxide fuel cells (SOFCs) is impeded by direct utilization of hydrocarbon fuels since SOFC anodes suffer from coking readily. We present an innovative design for enhancing the coking resistance of the conventional SOFC anode. A thin nano samaria doped ceria (SDC) catalyst layer has been deposited efficiently via infiltration on the wall surface of the Ni-yttria-stabilized zirconia (Ni-YSZ) anode internal gas diffusion channel (5-200μm in size) fabricated from freeze-drying tape-casting and vacuum-free infiltration. The efficiency for catalyst infiltration has been significantly improved by using hierarchically porous anode structure with open and straight channels. Single cells with nano SDC layer show very stable cell performance and a peak power density of 0.65Wcm^-2 at 800°C using methane as the fuel. High resolution transmission electron microscopy (HRTEM) analysis indicates for the first time that SDC layer can effectively prevent the formation or growth of nickel carbide (onset of coking), accounting for the excellent performance and structural stability of the Ni-based cermet anode.