Graphene Quantum Dots: a Novel Supercapacitor Electrode Material that Combines High Efficiency and Environmental Protection
PEI Hebing1, MO Zunli1,2,*, GUO Ruibin1,2, LIU Nijuan1, JIA Qianqian1, GAO Qinqin1
1 College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China 2 Research Center of Gansu Military and Civilian Integration Advanced Structural Materials, Lanzhou 730070, China
Abstract: Since the first discovery of graphene quantum dots (GQDs) by scientists in 2008, the preparation methods and application research have been widely concerned. With the rapid development of science and technology, researcher's investigation on carbon materials has started from three-dimensional graphite, two-dimensional graphene, to one-dimensional carbon nanotubes, and now to quasi-zero-dimensional graphene quantum dots. It has gone through a relatively long process. Graphene quantum dots have special physical and chemical properties, such as quantum confinement effect, edge effect, biocompatibility, photoluminescence and electroluminescence. Their applications in energy conversion and storage, photocatalysis, fluorescence sensor, drug delivery, bioimaging and therapeutic diagnosis have attracted more and more attention. Supercapacitor is a common energy storage device, which is known for its fast charge and discharge time, high power density and wide temperature range. Carbon-based electric double layer capacitors and Faraday tantalum capacitor materials based on transition metal oxides and conductive polymers are hot issues, and graphene quantum dots, as a newcomer to the carbon material family, have been applied to supercapacitor electrode materials. Medium, either as a monomer material or in combination with other nanomaterials, exhibits excellent performance. The main preparation methods of graphene quantum dots are “top-down” and “bottom-up”. The “top-down” method is to cut large-sized graphene and other carbon materials into small-sized quantum dots, while the “bottom-up” method is to synthesize quantum dots using molecules as precursors under certain conditions. In order to exert synergy between graphene quantum dots and other carbon materials, transition metal oxides, conductive polymers, etc., graphene quantum dots and three-dimensional graphene, carbon nanotubes, activated carbon, and their composites are synthesized through one-step or two-step reactions. Nanocomposites of manganese oxide, cerium oxide, nickel cobalt oxide, polyaniline and the like have better electrochemical performance than monomer materials, and greatly improve the overall performance of the supercapacitor. In this paper, the application progress of graphene quantum dots in supercapacitor electrode materials is summarized. The preparation methods of graphene quantum dots, graphene quantum dots and their nanocomposites are introduced as supercapacitor electrode materials respectively. A new type of supercapacitor with high energy density, excellent cycle stability and environmental friendliness is available for reference.
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2020, Vol. 34 
