Utilizing in-situ formed heterostructure oxides as a cathode for proton-conducting solid oxide fuel cells

By modifying the proton conductor BaTbO3 with the element Co, it is discovered that the solubility of Co in BaTbO3 is restricted to 20 mol.%, and phase segregations happen for high Co doping concentrations in BaTbO3. The fabrication of nominal BaTb0.5Co0.5O3 results in the in-situ development of the heterostructure cathode composed of BaTb0.8Co0.2O3+BaCoO3. The critical role of the interface between BaTb0.8Co0.2O3 and BaCoO3 in enhancing fuel cell performance is to accelerate charge transfer kinetics, thereby enabling proton-conducting solid oxide fuel cells (H-SOFCs) to operate at higher performance levels than cells employing BaTb0.8Co0.2O3 or BaCoO3 cathodes alone. Furthermore, the favorable chemical stability of the BaTb0.8Co0.2O3+BaCoO3 nanocomposite is maintained, thereby enhancing the fuel cell's operational stability. This research suggests that unanticipated phase segregation may occasionally improve the performance of the cathode, thereby presenting an interesting approach to cathode design in H-SOFCs.