▎ 摘　　要

A novel structural hybrid material consisting of La0.5Ca0.5CoO3-delta nanocrystals anchored on reduced graphene oxide is developed as highly efficient bifunctional catalyst for oxygen reduction and evolution reaction in alkaline electrolyte. Nanostructural La0.5Ca0.5CoO3-delta particles, which are synthesized by a modified amorphous citrate precursor method in advance, are anchored homogeneously on the surface of reduced graphene oxide sheets through a simple chemical reduction process at ambient temperature. Although reduced graphene oxide or La0.5Ca0.5CoO3-delta alone possesses some catalytic activity, their hybrid presents a remarkable oxygen reduction catalytic activity, which is on a par with that of the commercial 20 wt% Pt/C. This La0.5Ca0.5CoO3-delta/ reduced graphene oxide hybrid also exhibits outstanding activity for oxygen evolution reaction which surpassed that of IrO2, allowing it to become a highly active non-noble metal bi-catalyst for both oxygen reduction and evolution reaction. More importantly, the same hybrid displays extremely excellent catalytic durability and superior cycling stability to the commercial Pt/C + IrO2 catalyst in the rechargeable zinc-air batteries, becoming one of the most promising bi-catalysts with low-cost. The unexpected bifunctional catalytic activities and surprisingly cycling life arise from synergetic effects between La0.5Ca0.5CoO3-delta and graphene. The rechargeable Zn-air battery with the hybrid as catalyst delivered a large peak power density of 223.6 mW cm(-2) along with ultrastbale cyclability over 10,100 min at 5 mA cm(-2). (C) 2021 Elsevier B.V. All rights reserved.