Enhanced activities of nano-CeO2-δ@430L composites by zirconium doping for hydrogen electro-oxidation in solid oxide fuel cells

Ceria-zirconia solid solution nanoparticulates, Ce1-xZrxO2-delta (x = 0, 0.2, 0.3, 0.4, 0.6, 0.8 and 1.0), are impregnated into the porous 430L stainless steel scaffolds and evaluated as the anode catalysts for solid oxide fuel cells (SOFCs). Combined analyses of X-ray diffraction and Raman scattering reveal the fluorite cubic (c) structure up to x <= 0.3 transforms to a mixture of the cubic and metastable tetragonal (t '') phases for 0.4 <= x <= 0.8, with the onset of tetragonal distortions at x = 0.8. Temperature-programmed reduction in H-2 indicates that doping Zr4+ into the ceria lattice could improve the oxygen storage capacity. None-theless, the charge transfer process within the bulk Ce1-xZrxO2-delta or across the interfaces of Ce1-xZrxO2-delta vertical bar YSZ becomes increasingly sluggish at x >= 0.3. The two opposite effects yield the smallest anode polarization resistances at x = 0.3, e.g., 0.08 +/- 0.01 Omega cm(2) for Ce0.7Zr0.3O2-delta versus 0.24 +/- 0.02 Omega cm(2) for CeO2-delta or 0.26 +/- 0.04 Omega cm(2) for Ce0.4Zr0.6O2-delta at 800 degrees C. Furthermore, thin YSZ electrolyte fuel cells with impregnated La0.6Sr0.4Fe0.9Sc0.1O3-delta - YSZ cathode supports produce peak power densities of 1.24 W cm(-2) at 800 degrees C for nano-Ce0.7Zr0.3O2-delta@A430L anodes, approximately 80% higher than 0.67-0.70 W cm(-2) on nano-CeO2-delta@430L or nano-Ce0.4Zr0.6O2-delta@430L anodes. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.