Synthesis of Co 3 O 4 /reduced graphene oxide by one step-hydrothermal and calcination method for high-performance super
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ORIGINAL PAPER
Synthesis of Co3O4/reduced graphene oxide by one step-hydrothermal and calcination method for high-performance supercapacitors Xiao-Ming Yue 1 & Zi-Jing Liu 1 & Cui-Cui Xiao 1 & Mei Ye 1 & Zan-Peng Ge 1 & Cheng Peng 1 & Zi-Yi Gu 1 & Jun-Sheng Zhu 1 & Shuang-Quan Zhang 1 Received: 4 August 2020 / Accepted: 27 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In this work, a simple and environmental one step-hydrothermal and calcination method was used to prepare Co3O4/reduced graphene oxide (rGO) composite. The result shows that tiny Co3O4 nanoparticles are dispersed on rGO sheets to form a threedimensional structure, which provides more active sites than Co3O4 nanowires structure. When acting as an electrochemical supercapacitor, structure optimized Co3O4/rGO-120-12 electrode exhibits high specific capacitance of 1152 F/g at 1 A/g in 6 M KOH electrolyte. As an assemble device, Co3O4/rGO reveals higher specific capacitance (about 85 F/g) than Co3O4 (about 36 F/ g) at current density of 1 A/g and excellent stability with 89.1% after 5000 cycles. The device exhibits a relatively high energy density of 57.26 Wh/kg at a power density of 2240.68 W/kg. Hence, the superior pseudocapacitive performance of Co3O4/rGO can be ascribed to the synergy between rGO and Co3O4 as well as the excellent three-dimensional structure obtained by changing the hydrothermal conditions. Keywords Reduced graphene oxide . Co3O4 . Nanocomposites . Structure optimization . Supercapacitor
Introduction As one of the most efficient and practical technologies for e l e ct r o ch e m i c a l e n er gy c o nv e r s i o n an d st or a ge , supercapacitors have been widely used in many fields due to their high power density, fast charging and long cycle life [1]. The charge storage is based on the surface reaction of the electrode material, but in most materials, there is no ion diffusion [2]. Therefore, supercapacitors are promising alternative or complement to rechargeable batteries when high power delivery and/or rapid energy collection is required [3]. Supercapacitors can be divided into two types according to their working principles: double-layer supercapacitors and pseudo-capacitor supercapacitors.
* Xiao-Ming Yue [email protected] 1
Key Laboratory of Coal Processing and Efficient Utilization (Ministry of Education) and School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China
Double-layer supercapacitors (EDLC) use the double-layer effect to store and convert energy. Activated carbon is a typical material used in commercial EDLC supercapacitors due to its excellent structural properties [4, 5]. In 2004, British scientists Andre Geim and Kongstantin Novoselov [6] obtained graphene for the first time. Graphene has a very high theoretical specific surface area (2630 m2/g) [7], excellent electrical conductivity, mechanical strength, chemical stability, and thermal conductivity, making it a promising candidate for electronic devices such
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