CeO2 Nanowires Inserted into Reduced Graphene Oxide as Active Electrocatalyst for Oxygen Reduction Reaction

Abstract

Fabrication of an interconnected and conductive nano-architecture is a prospective strategy to design a high-performance and low cost electrocatalyst for oxygen reduction reaction (ORR). Herein, a novel nano-architecture assembled by graphene nanosheets and CeO₂ nanowires (NWs) with a hierarchical structure was developed by a facile hydrothermal process using ethanol/water as solvents without any organic additives. In this framework, graphene oxide (GO) was reduced to graphene and chemical bonding formed between the GO and CeO_{2 NWs} in a hydrothermal process. The imbedded CeO_{2 NWs} could prevent the restacking of the graphene sheets and improved the electrical conductivity of the hybrid catalyst. The effect of different ratios of GO to CeO_{2 NWs} in the hybrid were studied. The GO₃-CeO_{2 NWs} composite exhibited better catalytic performance with slow attenuation and high limiting current density 3.55 and 1.99 times higher than CeO_{2 NWs} and pure GO. The onset potential of GO₃-CeO_{2 NWs} is 0.13 V and 0.05 V positive shift from that of CeO_{2 NWs} and pure GO, respectively, suggesting that the GO₃-CeO_{2 NWs} hybrid had an excellent stability and activity for ORR. It was found that CeO_{2 NWs} served not only as an effective catalyst but also as an “oxygen buffer” to relieve oxygen insufficiency for ORR.