Nanoarchitectures constructed with single crystalline Co 3 O 4 spheres and MWCNTs: Temperature effect on the growth and
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Nanoarchitectures constructed with single crystalline Co3O4 spheres and MWCNTs: Temperature effect on the growth and supercapacitors Yuanhua Xiao1, Yongbo Cao2, Aiqin Zhang2, Dianzeng Jia1, and Feng Li1,2,3,* 1 Institute of Applied Chemistry, Xinjiang University, Urumqi 830046, P. R. China 2
State Laboratory of Surface and Interface Science and Technology, Zhengzhou University of Light Industry, Zhengzhou 450002, P. R. China 3
American Advanced Nanotechnology LLC, Missouri City, TX 77459, USA
*Corresponding author, Email: [email protected]; [email protected] ABSTRACT Nanoarchitectures consisting of single crystalline Co3O4 spheres and multi-walled carbon nanotubes (MWCNTs) have been constructed successfully. The effect of reaction temperature on the morphology of the products reveal that the growth rate dictates the shape and size of Co3O4 beads on and around MWCNTs. Single crystalline Co3O4 spheres around MWCNTs can be produced in large scale by elevating reaction temperature for the increased growth rate. The electrochemical properties of the hybrid materials were investigated by cyclic voltammetry (CV) and galvanostatic charge/discharge tests. The supercapacitors made with the nanoarchitectures show high specific capacitance of 445 F/g at a current density of 0.1 A/g and exhibit excellent cycling stability. INTRODUCTION Supercapacitors, as a new type of energy storage devices, have attracted great attention for their high power density, long cycle life, and short charge time. The devices have been already applied as power sources for electric vehicles, computers and so on [1-3]. According to the fundamental mechanisms that govern the capacitance, supercapacitors can be divided into 1) electrical double-layer capacitors (EDLCs), in which capacitance arises from charge separation at the electrode/electrolyte interface, and 2) electrochemical capacitors (ECs), in which the capacitance mainly origins from the dominant reversible redox reactions [1]. Recently, the researches related to ECs electrode materials have focused on constructing 3D hybrid nanoarchitectures, because of the potentials of enhancing their capacity and electrical conductivity. Extensive efforts have been made to search for alternative low-cost transition metal oxides as electrode materials. Among them, cobalt oxide (Co3O4) is considered one of the promising candidates for fabricating ECs electrodes for its low environmental footprint, low cost and an extremely high specific capacitance of 3560 F/g in theory. Hybrid nanoarchitectures, which incorporate Co3O4 on high conductivity MWCNTs, are thought as ideal materials to optimize the performances of supercapacitors. We have worked on constructing complex nanoarchitectures with Co3O4 materials for improving the electrochemical performances of supercapacitors [1, 2]. Recently, 3D Co3O4 nanoarchitectures, such as Co3O4 twin-spheres with sea urchin-like structures and 3D Co3O4 hierarchical materials consisting of nanosheets with porous structures, have been constructed
successfully. The superca
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