Designed synthesis of LaCoO3/N-doped reduced graphene oxide nanohybrid as an efficient bifunctional electrocatalyst for ORR and OER in alkaline medium

Developing inexpensive and advanced bifunctional electrocatalysts as substitutes for commercial precious metal-based electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of tremendous expectancy for rechargeable metal-air batteries. Herein, we demonstrate a rational wet-chemical route to fabricate a novel LaCoO3/N-doped reduced graphene oxide (LaCoO3/NrGO) nanohybrid with improved performances as a bifunctional electrocatalyst for ORR and OER. The assynthesized LaCoO3/N-rGO affords overwhelmingly superior ORR and OER electrocatalytic properties in comparison with LaCoO3, N-rGO and LaCoO3/reduced graphene oxide (LaCoO3/rGO). As compared with the most acknowledgedly efficient Pt-based bifunctional eletrocatalysts, e.g. 20 wt% Pt/C, LaCoO3/N-rGO displays a far higher OER activity associated with remarkably enhanced ORR and OER durabilities. Moreover, LaCoO3/N-rGO holds a better durability and a more rapid OER rate than those of the benchmark OER electrocatalyst RuO2. The improved ORR and OER electrocatalytic performances for LaCoO3/NrGO stem from the diminished size of LaCoO3 on rGO, reinforced synergistic effect between LaCoO3 and rGO, efficient N doping, and significantly low ohmic and kinetic impedances. This design strategy can be extended to construct composites of other perovskite-type oxides and carbonaceous materials, thereby providing the foundation for the developments of bifunctional eletrocatalysts in the rechargeable metal-air batteries. (C) 2017 Elsevier B.V. All rights reserved.