Few-Layer Graphene Functionalized by Carbon Nanotubes and MnO 2 Nanoparticles for High-Performance Supercapacitors
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JMEPEG (2019) 28:4095–4101 https://doi.org/10.1007/s11665-019-04156-2
Few-Layer Graphene Functionalized by Carbon Nanotubes and MnO2 Nanoparticles for High-Performance Supercapacitors Feng Qiu, Liyao Suo, Wenguang Xiao, Zhi He, Qingchuan Du, and Jun Chen (Submitted September 22, 2018; in revised form March 30, 2019; published online June 26, 2019) Few-layer graphene (FLG) exfoliated from graphite is an attractive electrode material due to its high conductivity and high chemical stability. But usually limited by their specific surface area (SSA), its capacitance needs to be improved when used in supercapacitors. In this study, FLG has been prepared by combining electrochemical exfoliation and thermal expansion. It has a SSA of 148 m2/g and delivers a capacitance of 55 F/g at a discharge current density of 1 A/g. To increase its capacitance, carbon nanotubes (CNTs) and MnO2 nanoparticles are functionalized onto FLG surface separately. Both modification could achieve a composite electrode with enhanced capacitance. The CNT/FLG and MnO2/FLG electrodes show a specific capacitance of 106 and 336 F/g at the current density of 1 A/g, respectively, while the former exhibits a much better rate performance and cycling stability than the latter. This work demonstrates an optional way to improve the performance of FLG-based supercapacitors. Keywords
carbon nanotubes, electrochemical exfoliation, fewlayer graphene, manganese dioxide nanoparticles, supercapacitors
1. Introduction Graphene is a type of important energy storage materials as electrodes or additives in supercapacitors or batteries due to their large surface area, high chemical stability, excellent thermal and electrical conductivity (Ref 1-6). After more than 10 years of intensive research, several synthesis approaches, such as chemical vapor deposition (CVD), chemical oxidation, liquid-phase exfoliation and electrochemical intercalation exfoliation (Ref 7-10), have been developed for large-scale production of graphene materials. CVD is a powerful technique in the synthesis of 1- or 2-layer continuous graphene films, while others are much suitable for the fabrication of graphene powder. Chemical oxidation method like Hummers approach is widely used in the production of 1- and few-layer graphene (FLG) materials, namely reduced graphene oxide (RGO) assisted by the following ultrasonication or reduction (Ref 4). Feng Qiu, College of Chemistry, Chemical Engineering and Environmental Engineering, Liaoning Shihua University, Fushun 113001, China; Liyao Suo, Wenguang Xiao, Zhi He, and Qingchuan Du, Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, School of Materials Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China; and Jun Chen, Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, School of Materials Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China; and School of Science, Nanjin
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