Electrochemical evaluation of Pr1.85M0.15NiO4+x (M=Ba, Sr, Ca) cathodes for protonic ceramic fuel cells

Pr1.85M0.15NiO4+x (M represents Ba, Sr, or Ca) materials were prepared and evaluated as cathodes for protonic ceramic fuel cells (PCFCs). Compared with the Sr and Ba doping methods, the Ca-doping approach slightly enhanced the generation of interstitial oxygen and the surface catalytic activity in Pr2NiO4. Furthermore, Ca-doping decreases the distance between O atoms in the lattice compared with the Sr and Ba-doped Pr2NiO4, facilitating the movement of charge carriers. Consequently, PCFCs employing Ca-doped Pr2NiO4 cathodes achieve a much greater power density of 1279 mW cm−2 at 700 °C compared to fuel cells employing Sr-doped or Ba-doped Pr2NiO4 cathodes. Furthermore, a PCFC employing a Ca-doped Pr2NiO4 cathode exhibited excellent long-term stability under working conditions and operated continuously for over 280 h without any discernible deterioration. These results indicate that the Ca-doped Pr2NiO4 cathode is a stable and effective candidate for PCFCs.