A new highly active and CO₂-stable perovskite-type cathode material for solid oxide fuel cells developed from A- and B-site cation synergy

Improving the activity of a cathode material towards the oxygen reduction reaction (ORR) and its tolerance against CO₂ impurities is of prime importance to realizing the application of solid oxide fuel cells that operate under intermediate temperatures (IT-SOFCs). Here, by adopting an A- and B-site co-doping strategy, we report a new perovskite-type oxide, Nd_0.2Sr_0.8Nb_0.1Co_0.9O_3-δ (N0.2SNC), as an active and CO₂-tolerant cathode material for IT-SOFCs. Compared with single-site doped Nd_0.2Sr_0.8CoO_3-δ (N0.2SC, A-site doping) and SrNb_0.1Co_0.9O_3-δ (SNC, B-site doping) and the parent oxide SrCoO_3-δ (SC), N0.2SNC shows improved electrocatalytic activity for the ORR and superior resistance towards CO₂ poisoning, achieving a low area specific resistance (ASR) of 0.037 Ω cm² at 650 °C. In addition, the ASR value of the N0.2SNC electrode only increases from 0.08 to 0.20 Ω cm² after operating for 300 min under an air atmosphere with 5% CO₂. A- and B-site cation synergy is obtained through co-doping, leading to the improved performance. A peak power density of 1563 mW cm⁻² is achieved at 650 °C. This A- and B-site cation synergy may offer a new avenue for developing high-performance and CO₂-stable cathode materials for IT-SOFCs.