Effect of fabrication method on properties and performance of bimetallic Ni0.75Fe0.25 anode catalyst for solid oxide fuel cells

Ni/Fe alloy-based anodes have attracted much attention recently due to their potential for improving anodic activity and suppressing carbon deposition when operating on carbon-containing fuels. However, some inconsistent results about the iron alloying effect were reported in literature. In the present work, we systematically studied the influence of synthesis method on properties and cell performances of a Ni0.75Fe0.25 + SDC (60:40 v/o) alloy-ceramic anode for solid oxide fuel cells. Three different methods, i.e. physical mixing route (PMR), simultaneous glycine nitrate process/sol–gel route (S-GNP) and combined GNP sol–gel route (C-GNP), were used. Samples were analysed by X-ray diffraction, temperature-programmed reduction/oxidation, scanning electron microscopy and electrochemical impedance spectroscopy. It was revealed that the phase structure of anode components, chemical interaction between nickel and iron, and the electrode microstructure were strongly dependent on the synthesis method. The coking resistance was found to be more sensitive to anode phase structure and chemical binding between Ni and Fe phases, whereas the cell power output was mainly determined by the electrode microstructure. As a result, the iron content of the NiFe-based anode should be carefully controlled in different preparation methods to achieve high cell performances.