Characterization of NiO-Al₂O₃ composite and its conductivity in biogas for solid oxide fuel cell

Abstract

NiO–Al₂O₃ nanocomposite has been synthesized by mixing combustion synthesized powders. The nanocomposite is an effective anode/anode functional layer for intermediate temperature solid oxide fuel cells. The TEM of NiO and Al₂O₃ revealed spherical particles of 30 nm and platelets of 70 nm, respectively. The XRD analysis of NiO–Al₂O₃ composite sintered at 900 °C showed presence of cubic NiO and rhombohedral α-Al₂O₃ which were chemically stable. However, above 1200 °C NiAl₂O₄ started to appear. The conductivity of NiO–Al₂O₃ was the highest in hydrogen (4.3 × 10⁻³ S/cm at 600 °C). In biogas, the conductivity was 3.2 × 10⁻³ S/cm with the activation energy of 0.67 eV. The stability of the composite in biogas was also examined.