Engineering of the A-site deficiency in La0.4Sr0.6Co0.7Fe0.2Nb0.1O3-δ perovskites for enhanced elelctrocatalytic oxygen reduction reaction

The development of efficient non-noble metal electrocatalysts for the oxygen reduction reaction (ORR) can aid the commercialization of fuel cells and metal-air batteries. Here, we developed a series of La 0.4 Sr 0.6 Co 0.7 Fe 0.2 Nb 0.1 O 3-δ (LSCFN) perovskites by engineering A-site deficiency to enhance their electrocatalytic activity for ORR in alkaline solutions. We found that LSCFN-0.90 with the highest amount of vacant A-sites has a highly oxidative oxygen species (O 2 2− /O − ) and an appropriate Co oxidation state - is a much better ORR catalyst in alkaline solutions compared to those with less vacant A-sites. The enhanced ORR kinetics enabled their use as the cathode catalyst in aluminum-air batteries, which also revealed better electrochemical performances for the catalyst with the highest A-site deficiency. Overall, the results demonstrate that an appropriate A-site cation deficiency in perovskites can enhance the ORR electrocatalytic activity.