Self-assembled Gd0.1Ce0.9O1.95-BaGd0.8La0.2Co2O6‒δ nanocomposite cathode for efficient protonic ceramic fuel cells

Protonic ceramic fuel cells (PCFCs) are characterized by a low activation energy for proton conduction and a high fuel utilization efficiency at low-to-intermediate temperatures. However, the sluggish oxygen reduction reaction kinetics on the cathodes drastically limit the power output performance of PCFCs. Herein, multiphase Gd0.1Ce0.9O1.95-BaGd0.8La0.2Co2O6‒δ (GDC-BGLC) nanocomposite cathodes are prepared by coupling self-assembly and sintering-free electrode construction methods. The nanocomposite cathode comprises mixed H+/e– conducting BGLC and O2− conducting GDC and BaCoO3 nanoparticles, and these phases are homogeneously mixed with coherent heterointerfaces. The nanocomposite cathode exhibits a significant increase in surface oxygen vacancies and three-phase boundaries, enhanced catalytic activity, and reduced activation energy for the oxygen reduction and water formation reactions. The results imply that the oxygen reduction and water formation reactions on the multiphase GDC-BGLC nanocomposite electrodes are most likely the dissociation, reduction and diffusion of oxygen species, which in turn is affected by the water vapor formed. An anode-supported single cell with the GDC-BGLC cathode exhibits a peak power density of 810 mW cm−2 at 700 °C with excellent operating stability at 650 °C for 110 h. This study provides a new strategy for the preparation of a high-performance and durable nanocomposite cathode for PCFCs.