Carbon quantum dots anchoring MnO2/graphene aerogel exhibits excellent performance as electrode materials for supercapacitor

Abstract

Manganese oxides/graphene composite material has become regarded as a highly promising electrode material for high-performance supercapacitors. However, some shortages such as low bonding strength and poor stability are faced to solve. In this work, carbon quantum dots serve as the bridge for connecting MnO2 and graphene, which contribute to synthesize the stable MnO2/carbon quantum dots/graphene composite aerogel. Due to the connection function of CQDs the stable combinations are formed between MnO2 nanoparticles and graphene nanosheets. Subsequently, the composite aerogel as-fabricated has the three-dimensional net structure, indicating a large specific surface area and abundant electron transport pathways. The MnO2/CQDs/GA electrode exhibits excellent electrochemical performance as compared to those of MnO2/GA and MnO2/G that are synthesized without the addition of CQDs. This composite electrode displays high specific capacitance of 721 F g-1 at 1 A g−1, good rate capability of 89.2% capacitance retention at 20 A g−1 and remarkable cycle stability of 92.3% capacitance retention after 10,000 at 10 A g−1. Moreover, the MnO2/CQDs/GA is quite stable and has preeminent electrochemical performance, which demonstrates the great potential for the development of high-performance supercapacitors.