Physicochemical properties of Ni-loaded yttrium stabilized zirconia nanotubes for solid oxide fuel cells

Yttrium-stabilized zirconia nanotubes (YSZNTs) were prepared using a conventional hydrothermal method, and their characteristics were compared with those of yttrium-stabilized zirconia nanoparticles (YSZNPs) synthesized in this study and with those of commercial YSZNPs (CYSZNPs). YSZNTs had widths and lengths of 20–30 nm and 100–700 nm respectively. The electrical conductivity of NiO (60.0 wt%)-loaded YSZNTs (40.0 wt%) was higher than those of NiO/YSZNPs and NiO/CYSZNPs at the same NiO loading. The zeta-potentials of YSZNTs in aqueous solution, determined by electrophoretic light scattering (ELS), indicated high positive surface charges at lower pH values, which is known to be related to surface stability, but negative values at high pH. The results of cyclic voltammetry (CV) and H2-temperature-programmed reduction (H2-TPR) confirmed that NiO(60.0 wt%)/YSZNTs (Ered = −0.445 mV) were more reduced than NiO/YSZNPs (Ered = −0.517 mV) and NiO/CYSZNPs (Ered = −0.516 mV).