Subscriber access provided by University of South Dakota
Article
One-step facile solvothermal synthesis of copper ferrite-graphene composite as a high-performance supercapacitor material Wang Zhang, Bo Quan, Chaedong Lee, Seung-Keun Park, Xinghe Li, Eunjin Choi, Guowang Diao, and Yuanzhe Piao ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/am507014w • Publication Date (Web): 13 Jan 2015 Downloaded from http://pubs.acs.org on January 17, 2015
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
ACS Applied Materials & Interfaces is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 39
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
One-step facile solvothermal synthesis of copper ferrite-graphene composite as a high-performance supercapacitor material Wang Zhang,ab Bo Quan, ab Chaedong Lee,ab Seung-Keun Park, ab Xinghe Li, ab Eunjin Choi, ab Guowang Diao,*c and Yuanzhe Piao,∗ab
Abstract In this work, we reported a facile approach to prepare a uniform copper ferrite nanoparticle-attached graphene nanosheet (CuFe2O4-GN). A one-step solvothermal method featuring the reduction of graphene oxide and formation of CuFe2O4 nanoparticles was efficient, scalable, green, and controllable. The composite nanosheet was fully characterized by X-ray diffraction (XRD), transmission electron microscopy
(TEM),
and
X-ray
photoelectron
spectroscopy
(XPS), which
demonstrated that CuFe2O4 nanoparticles with a diameter of approximately 100 nm were densely and compactly deposited on GN. To investigate the formation mechanism of CuFe2O4-GN, we discussed in detail the effects of a series of experimental parameters, including the concentrations of the precursor, precipitation agent, stabilizer agent, and Graphene oxide on the size and morphology of the resulting products. Furthermore, the electrochemical properties of CuFe2O4-GN composite were studied by cyclic voltammetry and galvanostatic charge-discharge
a
Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 151-742, Republic of Korea. E-mail:
[email protected]; Tel: +82 318889148 b Advanced Institutes of Convergence Technology, Suwon, 443-270, Republic of Korea c College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, 225002 Jiangsu, P. R. China. E-mail:
[email protected]; Tel: +86 51487975436, Fax: +86 514 87975244 1
ACS Paragon Plus Environment
ACS Applied Materials & Interfaces
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
measurements. The composite showed high electrochemical capacitance (576.6 F·g-1 at 1 A·g-1), good rate performance and cycling stability. These results demonstrated that the composite as a kind of electrode materials had a high specific capacitance and good retention. The versatile CuFe2O4-GN held great promise for application in a wide range of electrochemical fields because of the remarkable synergistic effects between CuFe2O4 nanoparticles and graphene. Keywords: CuFe2O4, graphene, solvothermal procedure, supercapacitor
1. Introduction Electrochemical capacitors have the potential to emerge as promising energy storage devices owing to the advantages of short charging times, a long cycle, and high power and energy density.1-3 The crucial task for constructing an electrochemical capacitor is exploring an electrode material with high energy and power densities. Transition metal oxides have been proved favorable for supercapacitors.4-5 For example, hydrous ruthenium dioxide (RuO2·nH2O) has significant potential for the fabrication of advanced electrodes owing to its excellent properties, which include high theoretical specific capacitance (720 F·g-1) and high electrical conductivity.6-7 However, the large-scale applications of RuO2·nH2O for supercapacitors are definitely hindered by its toxic nature, scarcity, and high cost. Hence, design of a desirable, low-cost electrode material with a longer cycling lifetime and higher energy density is imperative for electrochemical energy storage.8 Binary metal oxides, which exhibit good electrochemical performance, have been widely used in electrochemical applications, such as electrochemical capacitors,9 2
ACS Paragon Plus Environment
Page 2 of 39
Page 3 of 39
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
Li-ion batteries,10 fuel cells,11-12 and solar cells.13 Transition metal oxides with a general formula AB2O4 have a spinel crystal structure, which is very important for electrochemical capacitors, because it offers a robust crystalline architecture with three dimensional diffusion pathways.14 Currently, a number of spinel compounds have been investigated for electrochemical capacitors, including Fe3O4,15 MnFe2O4,16 and NiCo2O4.17 CuFe2O4 with inverse spinel structure is one of the most important ferrites in transition metal oxides. Transition metal oxides have been widely used in electronics and catalysts in recent years owing to the advantages exhibited in these materials that include environmental compatibility, high catalytic activity and easy separation.18-20 Sreedhar et al. synthesized CuFe2O4 nanoparticles as a magnetically recoverable and reusable catalyst for the synthesis of 5-substituted 1H-tetrazoles.21 Yen et al. reported a novel one-step-impregnation method to synthesize CuFe2O4 using meso-porous silica.22 This method enabled a true replication of the meso-structure with high yield and phase purity, while retaining the template morphology. As the anode for Li-ion batteries, carbon coated hollow CuFe2O4 spheres, which had a high specific capacity of 550 mA·h·g-1, were prepared using a polymer-template hydrothermal growth method by Jin et al.23 CuFe2O4 hollow fibers, which had a typical pseudocapacitive capacitance, were obtained by Zhao and his coworkers by electrospinning.24 Previously, we also reported the formation and capacitance property of porous CuFe2O4 nanospheres.25 Although CuFe2O4 has been regarded as a promising material for electrochemical capacitors because of its high theoretical capacity (895 mA·h·g-1) and low cost,23, 26-27 its inherent poor conductivity
3
ACS Paragon Plus Environment
ACS Applied Materials & Interfaces
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
is a negative factor that impedes its application in electrochemical capacitors. Graphene is an intriguing two-dimensional carbon nanomaterial that is widely utilized to design fascinating electrode materials for supercapacitors because of its ultra-thin nanostructure, excellent electrical conductivity, and mechanical stability.28-30 Recently, researchers have reported wide on the application of graphene-based transition metal oxide composites as electrochemical materials.31-36 The hybrid materials can improve electrochemical performance with the synergistic effect between graphene and transition metal oxides. In these systems, graphene has offered not only a conductive backbone to facilitate electron transport , but also mechanical structure that maintains the integrity of the electrode during the electrochemical process.37 In addition, graphene with metal oxide can be an economic and promising way to achieve high supercapacitor performance.38 To overcome the shortcomings of CuFe2O4, some approaches have been attempted to prepare graphene/CuFe2O4 hybrid electrodes by the hydrothermal method.20,
39
The preparation of graphene/CuFe2O4 hybrid materials as a high
performance supercapacitor is highly desirable, and there are few reports on the formation mechanism of the hybrid materials. In this work, we showed graphene nanosheets decorated with CuFe2O4 nanoparticles (CuFe2O4-GN) that integrate both the electrically conductive property of graphene and the high capacitance of CuFe2O4. The strategy for the composite formation was a simple one-step reaction that included the reduction of graphene oxide (GO) to graphene and the in-situ formation of CuFe2O4 on GN. The growth process of CuFe2O4 on GN was investigated by changing various
4
ACS Paragon Plus Environment
Page 4 of 39
Page 5 of 39
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
experimental parameters, which showed the formation mechanism of the product. Furthermore, the CuFe2O4-GN composites possessed good electrical capacitance, which held great promise for a wide range of electrochemical fields.
2. Experimental 2.1. Reagents CuCl2·2H2O, FeCl3·6H2O, sodium acetate (NaAc), and poly vinylpyrrolidone (PVP), ethylene glycol, graphite (
