Enhanced oxygen reduction reaction activity of Na⁺ and Ce⁴⁺ co-doped SrCoO_3-δ cathode for protonic ceramic fuel cells

The slow kinetics of oxygen reduction reaction (ORR) of the cathode has always been a barrier to the commercialization of proton ceramic fuel cells (PCFCs). This study proposes two new cathode materials, Ce_0.1Sr_0.9CoO_3-δ (CSC) and Na_0.1Ce_0.1Sr_0.8CoO_3-δ (NCSC). Both CSC and NCSC exhibit Pm-3 m space group cubic perovskite structure and have good chemical compatibility with BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ (BZCYYb) electrolyte. It is worth noting that by introducing alkaline Na⁺ ions for doping, the concentration of adsorbed oxygen species on the material surface significantly increases from 19.34 % to 31.69 %, and the ratio of adsorbed oxygen to lattice oxygen increases from 0.77 to 2.4, indicating that NCSC has excellent hydration ability and ORR catalytic activity. The NCSC cathode exhibits a minimum polarization resistance (Rp) of 0.075 Ω cm⁻² and a maximum power density (PPD) of 644 mW cm⁻² at 700 °C. These results validate NCSC could be considered as a promising cathode material for PCFCs.