Enhancing the ORR kinetics and CO2 tolerance in PrBaCoCuO5+ cathode for solid oxide fuel cells by bismuth doping

The sluggish kinetics of the oxygen reduction reaction (ORR) and susceptibility to CO2 poisoning present significant challenges in the application of intermediate temperature solid oxide fuel cells (IT-SOFCs). In this study, bismuth (Bi) was introduced as a dopant for the first time to enhance both the ORR activity and CO2 tolerance of PrBaCoCuO5+δ (PBCCO) cathode. Bi doping serves to concurrently modulate the oxygen vacancy content and carrier concentration. This dual regulation enhances the processes of oxygen adsorption, dissociation, and charge transfer, as evidenced by the distribution of relaxation time (DRT) technique. Furthermore, PBBCCO demonstrates exceptional CO2 tolerance and remarkable performance recovery following exposure to CO2-induced degradation. At 800 °C, the polarization resistance (Rp) and maximum power density (MPD) of PBBCCO were 0.026 Ω cm2 and 631 mW cm−2, respectively. Notably, Rp was reduced by 52.45%, and MPD exhibited an improvement of 45.11% at 800 °C. These findings highlight the significant impact of Bi doping on the performance of the PBCCO double perovskite cathode, underscoring its crucial importance for future developments of novel cathode materials.