Investigating the microstructure and catalytic properties of Ni/YSZ cermets as anodes for SOFC applications Original Research Article

Porous Ni/YSZ cermets (YSZ: yttria stabilized zirconia) have been extensively studied as anodes for solid oxide fuel cells (SOFCs) due to its low cost, high electrical conductivity, chemical stability, and thermal expansion coefficient close to that of YSZ-electrolyte. The properties of these anodes are highly dependent on the particle size and microstructure of the cermet. In the present work, Ni/YSZ cermet was prepared with 30 wt% of NiO by two different routes, co-precipitation (CP) and combustion (CB), and calcination at 600, 800 and 1000 °C. The prepared cermets were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and temperature programmed reduction (TPR). The mean crystallite size of NiO is smaller for CB samples (20–33 nm), showing a higher Ni dispersion of these systems. Also, CB samples presented a more homogeneous particle size distribution, mainly at high calcination temperatures. The cermets also presented good catalytic activity and stability at 900 °C in steam reforming of methane, showing high resistance to coke deposition and to sintering of metallic particles.