Phases in copper-stabilized zirconia solid oxide fuel cells anode material

Solid oxide fuel cells (SOFC) are emerging as an alternate source of energy. Anodes form one of the components of the fuel cells. Ni/Yttrium stabilized zirconia is a classic anode material for SOFC when hydrogen is used as the fuel source, but it is not that effective when methane is used as fuel source due to carbon deposition on the anode. Recently, copper stabilized zirconia has been investigated as anode material for SOFC for its self-cleaning properties. We have tried to investigate phases in copper stabilized zirconia for better understanding of its properties. Copper stabilized zirconia (CSZ) with different CuO loading was prepared by the solid-state reaction method. X-ray diffraction studies on these samples reveal only monoclinic zirconia phase in those samples loaded with less than 5 mol% of CuO. Traces of monoclinic CuO along with monoclinic ZrO2 is observed in the samples when loading of CuO is between 5 and 20 mol%. Orthorhombic copper zirconium oxide and monoclinic zirconia phases were observed when CuO loading was greater than 20 mol%. Scanning and back-scattered electron micrographs reveal a clear two-phase structure only in the samples with greater than 20 mol% of CuO loading. Atomic force microscopy carried out on 33 mol% loaded zirconia shows a three-phase structure with flattened seven-fold-coordination of Zr4+ with oxygen.