Graphene\nQuantum Dots Supported by Graphene Nanoribbons\nwith Ultrahigh Electrocatalytic Performance for Oxygen Reduction

Abstract

A new\nclass of oxygen reduction reaction (ORR) catalysts based\non graphene quantum dots (GQDs) supported by graphene nanoribbons\n(GNRs) has been developed through a one-step simultaneous reduction\nreaction, leading to ultrahigh performance for O reduction with an\nexcellent electrocatalytic activity (higher limiting current density\nand lower overpotential than those of platinum) and high selectivity\nand stability in alkaline media comparable to the best C-based ORR\ncatalysts reported so far. Electron microscopy revealed numerous surface/edge\ndefects on the GQD/GNR surfaces and at their interface to act as the\nactive sites. This, coupled with efficient charge transfer between\nthe intimately contacted GQDs and GNRs, rationalized the observed\nultrahigh electrocatalytic performance for the resultant GQD-GNR hybrids.\nThus, this study opens a new direction for developing low-cost, highly\nefficient, C-based ORR electrocatalysts.