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

By modifying the proton conductor BaTbO 3 with the element Co, it is discovered that the solubility of Co in BaTbO 3 is restricted to 20 mol.%, and phase segregations happen for high Co doping concentrations in BaTbO 3. The fabrication of nominal BaTb 0.5 Co 0.5 O 3 results in the in-situ development of the heterostructure cathode composed of BaTb 0.8 Co 0.2 O 3 +BaCoO 3. The critical role of the interface between BaTb 0.8 Co 0.2 O 3 and BaCoO 3 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 BaTb 0.8 Co 0.2 O 3 or BaCoO 3 cathodes alone. Furthermore, the favorable chemical stability of the BaTb 0.8 Co 0.2 O 3 +BaCoO 3 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. [ABSTRACT FROM AUTHOR]