Bi-functional hybrid catalysts of pyrochlore Bi₂Ru₂O₇ nanoparticle-reduced graphene oxide nanosheet composites for a lithium-oxygen battery cathode

For the development of rechargeable lithium-oxygen (Li-O₂) batteries, it has been necessary to solve the issue of sluggish kinetics of both oxygen reduction reaction and oxygen evolution reaction. A bi-functional hybrid catalyst composed of pyrochlore Bi₂Ru₂O₇ nanoparticles (BRO NPs) and reduced graphene oxide (rGO) sheets was prepared and its catalytic properties were investigated for application in Li-O₂ batteries. As-prepared BRO NPs anchored on rGO composites (BRO@rGO) in O₂-electrode exhibited high initial discharge capacity (ca. 6022.8 mAh g⁻¹). Additionally, the BRO@rGO electrode showed lifetime stability over 56 cyclings with a lower over-potential of 1.15 V at a current density of 200 mA g⁻¹ when the charge/discharge capacity was limited to 500 mAh g⁻¹, as compared with BRO NPs and ketjenblack carbon. This improved performance proves that this composite material of pyrochlore BRO NPs with rGO nanosheets can be promising ORR/OER catalysts for the development of Li-O₂ batteries.