▎ 摘　　要

A composite consisting of lead ruthenate nanocrystals with an expanded pyrochlore structure on reduced graphene oxide nano-sheets, is reported as an efficient bifunctional catalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Comparative studies for ORR show that the composite produces highly positive synergic coupling effects, strengthening a four-electron catalytic route, i.e., more positive onset potential, higher limiting current density, much smaller Tafel slope, and more durable catalytic performance after thousands of voltammetric cycling than pristine material. The composite also functions as an excellent and durable OER catalyst, exceeding the performance of NiCo2O4 and RuO2. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.