Surface manipulation of a triple-conducting cathode for protonic ceramic fuel cells to enhance oxygen reduction activity and CO2 tolerance

One of the main obstacles limiting the performance of protonic ceramic fuel cells (PCFCs) is the sluggish kinetics of the oxygen reduction reaction (ORR) at reduced temperatures. Here, the surface manipulation of a triple-conducting cathode BaCe0.5Pr0.3Y0.2O3−δ (BCPY) by an efficient catalyst coating PrNi0.5Co0.5O3−δ (PNC) to enhance the ORR activity and CO2 tolerance is reported. The developed PNC-coated BCPY cathode achieves the polarization resistance of 0.25 and 1.00 Ω cm2 at 600 and 500 °C, respectively, approximately 1/5 of that for the pristine BCPY cathode (0.99 and 4.79 Ω cm2), while maintaining an excellent CO2 tolerance. The single cell on a BaZr0.8Yb0.2O3−δ electrolyte also exhibits a high peak power density of 0.79 W cm−2 at 700 °C and a stable operation for 200 h at 600 °C. Such high ORR activity is mainly attributed to the synergistic effect of BCPY support and PNC nanoparticles. Namely, BCPY provides a triple-conducting path (mainly protons), and PNC nanoparticles facilitates surface oxygen exchange and steam adsorption/desorption processes due to the enriched surface oxygen vacancies. This study will provide a new design strategy for developing high-performance PCFCs cathode.