BaTb0.3Fe0.7O3-delta: a new proton-conductor-derived cathode for proton-conducting solid oxide fuel cells

BaTbO3 is a much less focused proton-conductor than the traditional BaCeO3-BaZrO3 system due to its lower proton conductivity. However, the present study reveals that using BaTbO3 as the parent material to form the new BaTb0.3Fe0.7O3-delta (BTF) can boost the cathode performance for proton-conducting solid oxide fuel cells (H-SOFCs). Compared with the traditional Fe-doped BaZrO3 (BZF), the electronic structure of BTF is regulated due to the presence of Tb3+ and Tb4+, leading to more abundant oxygen vacancies and improved oxygen reduction reaction activities compared with BZF, which have been demonstrated by both experiments and first-principles calculations. The slightly decreased proton diffusion by using BaTbO3 compared with BaZrO3 is compensated by the greatly enhanced oxygen diffusion and surface exchange abilities, leading to a record-high performance for the BTF cathode compared with other proton conductor-derived cathodes for H-SOFCs.