The annealing influence on the microstructure and performance of Au@Ni core-shell bimetal as the cathode of low-temperature solid oxide fuel cells

• A facile and optimized co-reduction, annealing synthesis route of Au85@Ni15 was developed.
• Core-shell structures of Au85@Ni15 were well kept in the uniform cathode films.
• A highly active property towards oxygen reduction reactions was achieved at 500 °C.
• Morphological evolution and corresponding impedance of Au85@Ni15/GDC were thoroughly investigated.

Core-shell nanoparticles of Au@Ni bimetal with the composition of Au:Ni = 85:15 was developed successfully by facile co-reduction and annealing synthesis route. The forming mechanism of the nano core-shell was proposed. The annealing conditions based on the morphology, microstructure and evolution of the core-shell structures were analyzed and revealed by scanning electron microscope in detail. The core-shell structures were well kept after the uniform films of Au85Ni15 were annealed on top of the GDC (Ce0.9Gd0.1O1.95) electrolyte. The complex impedance of the symmetrical half cells of Au@Ni/GDC/Au@Ni was performed at 500 °C. Under the optimal annealing conditions, the area specific resistance for the cathode on top of GDC was 0.25 Ω cm2 at 500 °C. And the power density of the anode supported cell Au@Ni/GDC/-NiO with the optimal profile was 153, 292, 464, 590, and 835 m Wcm−2 at 450, 475, 500, 525, 550 °C, respectively.