Electrochemical deposition of ceria nanostructures decorated with metal nanoparticle for high-temperature catalysis

Abstract

Solid oxide fuel cells (SOFCs) are promising next generation energy devices that generate electric power by electrochemical reactions of fuels with high efficiency. Moreover, in addition to hydrogen, SOFCs can directly utilize natural gas that is commercially available at the moment. However, the state-of-the-art SOFC anode, a composite of nickel and yttria-stabilized-zirconia, degrades performance due to severe carbon coking of the Ni surface at hydrocarbon fuel operating conditions. Here, I developed a two-step method of coating a Sm-doped $CeO_2$ (SDC) nanostructure containing nickel nanoparticles on Ni/YSZ electrode surfaces, which remarkably enhances SOFC anode performance and durability. $CeO_2$ is a key material to achieve a coking-resistant and electrochemically active anode under methane-fed conditions due to its high coking resistance and favorable electro-catalytic activity. Furthermore, metal nanoparticles effectively promote chemical reforming and electrochemical oxidation reactions. Highly porous SDC layers uniformly decorated with Ni nanoparticles were synthesized via a simple, scalable, cost-effective coating method known as cathodic electrochemical deposition. The influence of process variables on the physical characteristics were characterized by SEM, TEM, XRD and EDS. It turned out that the Ni-SDC overcoat significantly enhanced chemical and electrochemical methane oxidation at 650℃, which were measured by gas chromatography and electrochemical impedance spectroscopy. These observations suggest the coating method is technically valuable as a solution to suppress the SOFC anode deterioration.