“…Various nonprecious electrocatalysts like transition metal oxides, 11,13,16,17 metal carbides, [22][23][24] and perovskite oxides [25][26][27] have been investigated as cathode catalysts for LOBs. It should be noted that transition metal oxides possess relatively low electrical conductivity and poor stability, 28 and metal carbides have limited active sites because of the aggregation of metal particles. By contrast, perovskite oxides, a class of mixed-metal oxides, have a structural formula of ABO 3 , where A is a lanthanide, alkaline or rare-earth cation, and B is a transition metallic element from the 3d, 4d or 5d configurations.…”