Heterogeneous nanograin structured NiO-YSZ anodes via a water-in-oil microemulsion route for solid oxide fuel cells

Abstract A unique nanostructured NiO-yttria-stabilized zirconia (YSZ) composite is synthesized in-situ via a water-in-oil microemulsion technique for the solid oxide fuel cell (SOFC) anode. Thermogravimetric analysis and X-ray diffraction confirm that as-synthesized powders are crystallized in-situ at ∼500 °C as the distinct NiO and YSZ phases without any impurities. Moreover, transmission electron microscopy analysis reveals that the as-synthesized primary particles via microemulsion are ∼40 nm in size and have a characteristic structure in which NiO and YSZ nanograins are heterogeneously distributed. The electrochemical activity of the nanostructured NiO-YSZ composite is evaluated using an YSZ supported cell with a La 0.8 Sr 0.2 MnO 3-δ -YSZ (50:50 wt.%) cathode. The maximum power density of the SOFC employing the microemulsion-mediated NiO-YSZ anode is 2.2 times greater than that of the SOFC with the conventionally ball-milled nano-sized NiO-YSZ anode. The higher performance with our nanocomposite NiO-YSZ anode is primarily attributed to its heterogeneous nanograin structure, thus leading to a significant increase in triple phase boundary densities.