Palygorskite mixed with Ho-based perovskite as a promising cathode material for solid oxide fuel cell

Porous palygorskite (Pal) was mixed with Ho0.9Sr0.1Cr0.5Fe0.5O3-δ (HSCF) perovskite to prepare a novel cathode material for SOFC due to large specific surface area and nano-scaled internal channels. Calcination of HSCF was preceded under 1000 °C by Thermogravimetry and differential scanning calorimetry techniques (TG-DSC) and X-ray diffraction (XRD) analysis. Field emission scanning electron microscopy (FESEM) and IR manifested that Pal was mixed homogeneously with HSCF. Brunauer-Emmett-Teller (BET) analysis proved that surface areas of cathode increased from 0.18 m2 g−1 to 4.23 m2g−1after mixing with palygorskite. In addition, the performances of the single cell (NiO-GDC|GDC|HSCF-GDC and NiO-GDC|GDC|HSCF-Pal-GDC) were also measured at 450-550 °C when the 99% H2 and ambient air were fuels of anode and cathode, respectively. Corresponding the maximum power density were 14.32 mW·cm−2 and 28.43 mW·cm−2 at 500 °C. When the single cell operating temperature was raised to 550 °C, the performance of single cell NiO-GDC|GDC|HSCF-GDC continues to enhance, while another ome decreased sharply. BET values of the cathode with mixing Pal after cell test declined from 4.23 m2 g−1 to 0.11 m2 g−1, which indicated the collapsing of the pores in Pal at the cell operating temperature and impeded the performance of the cell. The operating temperature of the single cell after mixing Pal in electrode couldn't exceed 500 °C. The electrochemical impedance spectra (EIS) was also used to analysis the factors influencing cell performance. Therefore, HSCF-Pal as a promising cathode can be used as low temperature solid oxide fuel cell.