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High capacitance properties of electrodeposited PANI-Ag nanocable arrays
Materials Letters 86 (2012) 77–79
Contents lists available at SciVerse ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
High capacitance properties of electrodeposited PANI-Ag nanocable arrays Yujuan Xie a, Zhenxing Song b,n, Suwei Yao c, Hongzhi Wang c, Weiguo Zhang c, Yingwu Yao d, Baofeng Ye e, Changben Song e, Jun Chen f, Yanjun Wang g a
Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China College of Science, Tianjin University of Science and Technology, Tianjin 300457, PR China c Department of Applied Chemistry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China d Electrochemical Surface Technology Research Laboratory, School of Chemical Engineering and Technology, Hebei University, Tianjin 300130, PR China e Bureau of Education, Xianshuigu, Tianjin 300350, PR China f National Engineering Research Centre of Advanced Energy Storage Materials Co. Ltd., Shenzhen 518054, PR China g Shanghai Xuntest Energy Technology Co. Ltd., Shanghai 201400, PR China b
a r t i c l e i n f o
abstract
Article history: Received 13 April 2012 Accepted 9 July 2012 Available online 20 July 2012
Highly uniform polyaniline-Ag nanocable arrays (NCAs) had been electrodeposited into the anodic aluminum oxide (AAO) template for supercapacitor studies. Each nanocable has the average values dimensions, with approximately length of 20 mm and diameter of 100 nm. The supercapacitor using PANI-Ag nanocable arrays as electrode showed excellent stability over a long cycle-life by cyclic voltammogram tests. The capacitance value of the electrode was as high as 850 Fg 1 at 10 mVs 1 sweep rate, and there was a decrease in capacitance with an increase of current density. These interesting results indicated that PANI-Ag NCAs could be an ideal alternative to carbon based electrodes, regular conducting polymers and metal oxides for the fabrication of supercapacitor. & 2012 Elsevier B.V. All rights reserved.
Keywords: Supercapacitor Electrodeposition Nanocable array Polyaniline Energy storage and conversion Nanocomposites
1. Introduction Supercapacitor has attracted great interest for the important application in the area of electrochemical energy storage because of increasing demand of digital communication, electric vehicles and other electric devices at high pulse power level [1,2]. Supercapacitors have higher capacitance and energy density compared to common capacitors, and higher power density than batteries. It is a diverse class of device which can incorporate a variety of active electrode materials like activated carbon, conducting polymers and metal oxides [3–7]. Among the various types of materials investigated as electrode active materials of supercapacitors, polyaniline (PANI) is studied extensively because it is inexpensive, easy to synthesize and chemically stable. Capacitance depends on morphology of PANI deposits, which in turn depends on the nature of substrate used for electrochemical deposition. Depositing as the PANI-Ag nanocable arrays (NCAs) is an excellent solution for PANI to enhance energy density and improve its intensity. In this paper, the electrodeposited PANI-Ag NCAs were assembled as supercapacitor and the capacitance value is about 850 Fg 1. This supercapacitor is novel and easy to accomplish,
n
Corresponding author. Tel./fax: þ 86 13902078190. E-mail addresses: [email protected], [email protected] (Z. Song).
0167-577X/$ - see front matter & 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.matlet.2012.07.026
while its capacitance value is much higher than most of PANI supercapacitors.
2. Experimental procedure 2.1. Fabrication of PANI-Ag nanocable arrays All experiments were carried out in room condition (2571 1C). Analytical grade chemicals, vacuum distilled aniline and double-distilled water were used for all experiments. The anodic aluminum oxide (AAO) template was used as a template for the PANI-Ag nanocable arrays. The method to prepare ordered AAO template using a two-step anodization technique is described elsewhere [8]. The first anodization was performed in 0.5 M oxalic acid solution by applying 40 V dc. After the first template was dissolved in 25 wt% H3PO4 solution at 60 1C, the second anodization was performed in the same condition like the first step. Furthermore, a subsequent etching treatment was carried out in a 5 wt% H3PO4 solution at 30 1C for 2 h to remove the barrier layer and widen slightly the pores of the AAO template. In order to deposit PANI-Ag NCAs, a layer of Au film was sputtered onto one side of the through-hole template. The AAO/ Au substrate serves as the working electrode in a three-electrode potentiostatic control electrodeposition system with a saturated
78
Y. Xie et al. / Materials Letters 86 (2012) 77–79
calomel electrode (SCE) as reference electrode, a 1.0 cm 1.0 cm platinum plate as a counter electrode. Fig. 1 shows the preparation of PANI-Ag nanocable arrays, and the steps are as follows: (1) PANI was electrodeposited into the pores of AAO. The nanotube arrays of PANI were carried out in the nanopores of the AAO/Au substrate by electrodeposition in the potential 1.0 V (SCE), and the thickness of the PANI was 0.4 nm (Fig. 2b). The solution for deposition of PANI nanotube arrays contained 0.1 M aniline and 0.2 M H2SO4; (2) The AAO/Au substrate was washed by distilled water and then Ag nanowires were deposited into the PANI nanotubes in the potential 0.1 V (SCE). The electrolyte for deposition of Ag nanowires contained 0.5 M AgNO3 and 0.2 M H3BO3; (3) the substrate was dipped into a solution of 1 M NaOH for 3 h to dissolve the AAO template; (4) the superfluous PANI was removed by supersonic and the PANI-Ag NCAs were washed with 0.5 M H2SO4 and stored in 0.2 M H2SO4 solution for further experiments. The length of the PANI-Ag nanocable arrays was 20 mm, and diameter was 100 nm (Fig. 2c).
2.2. Electrochemistry tests and structure characterization Electrochemical preparation and cyclic voltammetry were carried out by using electrochemical workstation (CHI 660b). The AAO/Au substrate serve as the working electrode in a threeelectrode potentiostatic control and direct current (DC) electrodeposition system with a saturated calomel electrode (SCE) as reference electrode, a 1.0 cm 1.0 cm platinum plate as a counter electrode, and a mixed electrolyte of 0.2 M aniline and 0.5 M H2SO4 was used for cyclic voltammetry and capacitor studies on PANI-Ag NCAs. Capacitance was determined from the discharge curves using the equation given below: C ¼It/vm [9], where I is the current (A) used for charge–discharge cycling, t is the time (s), m is the
Fig. 1. Preparation of PANI-Ag nanocable arrays.
Fig. 2. SEM and TEM images of PANI-Ag nanocable arrays.
mass (g) of PANI and v corresponds to potential (V) window of cycling. The morphology of the PANI-Ag NCAs was observed by a scanning electron microscope (SEM, TESCAN 5130SB) and transmission electron microscopy (TEM, Tecnai G2 F20).
3. Results and discussion The SEM image of PANI-Ag NCAs (Fig. 2c) shows that the sample consists of a large quantity of PANI-Ag NCAs, and the nanocables are aligned perpendicularly to the Au layer. Each nanocable has average values dimensions, with approximately length of 20 mm and diameter of 100 nm. The density is about 1010/cm2. Fig. 2a is the TEM image of PANI nanotube. The TEM image (Fig. 2b) shows that the thickness of PANI coated on Ag nanowire is about 0.4 nm. The cyclic voltammogram (CV) of the supercapacitors carried out at a scan rate of 50 mVs 1 is shown in Fig. 3. The CV curve after 1000 cycles is similar to the initial curve which indicates that the electrodes are fairly stable over a long cycle-life. Fig. 4 illustrates the capacitance of PANI-Ag NCAs at different current densities. It is seen that the capacitance values of PANI-Ag NCAs are fairly high at all current densities of cycling, and there is a decrease in capacitance with an increase of current density. The decrease in capacitance is due to a decrease in utilization rate of the amount of PANI with increasing charge–discharge current density. The value reported here is as high as 850 F g 1 which is higher than most of PANI supercapacitors. Moreover, stable long cycle-life, high charge–discharge current densities and low dosage of raw materials make the present system attractive.
4. Conclusion In summary, a novel electrode of PANI-Ag nanocable arrays is fabricated for supercapacitor. PANI-Ag NCAs is prepared by electrodeposition in the pores of the AAO template. The freestanding and vertically aligned PANI-Ag NCAs are uniform. Each PANI-Ag NCAs has average values dimensions, with approximately length of 20 mm and diameter of 100 nm. The density is about 1010/cm2, and the thickness of PANI coating is about 0.4 nm. The capacitance value calculated from a typical experimental data is as high as 850 F g 1 for PANI-Ag NCAs electrodes at 10 mVs 1 sweep rate. The capacitance values of PANI-Ag NCAs are fairly high at all current densities of cycling, and electrodes
Fig. 3. Cyclic voltammograms recorded after 100 and 1000 cycles.
Y. Xie et al. / Materials Letters 86 (2012) 77–79
79
References
Fig. 4. Capacitance of the supercapacitor at different current densities.
are found to be fairly stable over a long cycle-life. The result revealed that the PANI-Ag NCAs could be an ideal alternative to carbon based electrodes, regular conducting polymers and metal oxides for the fabrication of supercapacitor.
[1] Dubal DP, Patil SV, Kim WB, Lokhande CD. Supercapacitors based on electrochemically deposited polypyrrole nanobricks. Mater. Lett. 2011;65:2628–31. [2] Sun W, Chen XY. Fabrication and tests of a novel three dimensional micro supercapacitor. Microelectron. Eng. 2009;86:1307–10. [3] Staiti P, Lufrano F. Investigation of polymer electrolyte hybrid supercapacitor based on manganese oxide-carbon electrodes. Electrochim. Acta 2010;55:7436–42. [4] Sivaraman P, Rath SK, Hande VR, Thakur AP, Patri M, Samui AB. All-solidsupercapacitor based on polyaniline and sulfonated polymers. Synth. Metals 2006;156:1057–64. [5] Gao FL, Zhang LJ, Huang SM. Fabrication horizontal aligned MoO2/singlewalled carbon nanotube nanowires for electrochemical supercapacitor. Mater. Lett. 2010;64:537–40. [6] Wang YHi, Zhitomirsky I. Cathodic electrodeposition of Ag-doped manganese dioxide films for electrodes of electrochemical supercapacitors. Mater. Lett. 2011;65:1759–61. [7] Gong LY, Liu XH, Lu LH. Synthesis of MnO2 nanorods from a ZnO template and their capacitive performances. Mater. Lett. 2012;67:226–8. [8] Song ZX, Xie YJ, Yao SW, Wang HZ, Zhang WG, Tang ZY. Microstructure and magnetic properties of electrodeposited Co/Cu multilayernanowire arrays. Mater. Lett. 2011;65:1562–4. [9] Mondal SK, Keshab Barai, Munichandraiah N. High capacitance properties of polyaniline by electrochemical deposition on a porous carbon substrate. Electrochim. Acta 2007;52:3258–64.
Contents lists available at SciVerse ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
High capacitance properties of electrodeposited PANI-Ag nanocable arrays Yujuan Xie a, Zhenxing Song b,n, Suwei Yao c, Hongzhi Wang c, Weiguo Zhang c, Yingwu Yao d, Baofeng Ye e, Changben Song e, Jun Chen f, Yanjun Wang g a
Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China College of Science, Tianjin University of Science and Technology, Tianjin 300457, PR China c Department of Applied Chemistry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China d Electrochemical Surface Technology Research Laboratory, School of Chemical Engineering and Technology, Hebei University, Tianjin 300130, PR China e Bureau of Education, Xianshuigu, Tianjin 300350, PR China f National Engineering Research Centre of Advanced Energy Storage Materials Co. Ltd., Shenzhen 518054, PR China g Shanghai Xuntest Energy Technology Co. Ltd., Shanghai 201400, PR China b
a r t i c l e i n f o
abstract
Article history: Received 13 April 2012 Accepted 9 July 2012 Available online 20 July 2012
Highly uniform polyaniline-Ag nanocable arrays (NCAs) had been electrodeposited into the anodic aluminum oxide (AAO) template for supercapacitor studies. Each nanocable has the average values dimensions, with approximately length of 20 mm and diameter of 100 nm. The supercapacitor using PANI-Ag nanocable arrays as electrode showed excellent stability over a long cycle-life by cyclic voltammogram tests. The capacitance value of the electrode was as high as 850 Fg 1 at 10 mVs 1 sweep rate, and there was a decrease in capacitance with an increase of current density. These interesting results indicated that PANI-Ag NCAs could be an ideal alternative to carbon based electrodes, regular conducting polymers and metal oxides for the fabrication of supercapacitor. & 2012 Elsevier B.V. All rights reserved.
Keywords: Supercapacitor Electrodeposition Nanocable array Polyaniline Energy storage and conversion Nanocomposites
1. Introduction Supercapacitor has attracted great interest for the important application in the area of electrochemical energy storage because of increasing demand of digital communication, electric vehicles and other electric devices at high pulse power level [1,2]. Supercapacitors have higher capacitance and energy density compared to common capacitors, and higher power density than batteries. It is a diverse class of device which can incorporate a variety of active electrode materials like activated carbon, conducting polymers and metal oxides [3–7]. Among the various types of materials investigated as electrode active materials of supercapacitors, polyaniline (PANI) is studied extensively because it is inexpensive, easy to synthesize and chemically stable. Capacitance depends on morphology of PANI deposits, which in turn depends on the nature of substrate used for electrochemical deposition. Depositing as the PANI-Ag nanocable arrays (NCAs) is an excellent solution for PANI to enhance energy density and improve its intensity. In this paper, the electrodeposited PANI-Ag NCAs were assembled as supercapacitor and the capacitance value is about 850 Fg 1. This supercapacitor is novel and easy to accomplish,
n
Corresponding author. Tel./fax: þ 86 13902078190. E-mail addresses: [email protected], [email protected] (Z. Song).
0167-577X/$ - see front matter & 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.matlet.2012.07.026
while its capacitance value is much higher than most of PANI supercapacitors.
2. Experimental procedure 2.1. Fabrication of PANI-Ag nanocable arrays All experiments were carried out in room condition (2571 1C). Analytical grade chemicals, vacuum distilled aniline and double-distilled water were used for all experiments. The anodic aluminum oxide (AAO) template was used as a template for the PANI-Ag nanocable arrays. The method to prepare ordered AAO template using a two-step anodization technique is described elsewhere [8]. The first anodization was performed in 0.5 M oxalic acid solution by applying 40 V dc. After the first template was dissolved in 25 wt% H3PO4 solution at 60 1C, the second anodization was performed in the same condition like the first step. Furthermore, a subsequent etching treatment was carried out in a 5 wt% H3PO4 solution at 30 1C for 2 h to remove the barrier layer and widen slightly the pores of the AAO template. In order to deposit PANI-Ag NCAs, a layer of Au film was sputtered onto one side of the through-hole template. The AAO/ Au substrate serves as the working electrode in a three-electrode potentiostatic control electrodeposition system with a saturated
78
Y. Xie et al. / Materials Letters 86 (2012) 77–79
calomel electrode (SCE) as reference electrode, a 1.0 cm 1.0 cm platinum plate as a counter electrode. Fig. 1 shows the preparation of PANI-Ag nanocable arrays, and the steps are as follows: (1) PANI was electrodeposited into the pores of AAO. The nanotube arrays of PANI were carried out in the nanopores of the AAO/Au substrate by electrodeposition in the potential 1.0 V (SCE), and the thickness of the PANI was 0.4 nm (Fig. 2b). The solution for deposition of PANI nanotube arrays contained 0.1 M aniline and 0.2 M H2SO4; (2) The AAO/Au substrate was washed by distilled water and then Ag nanowires were deposited into the PANI nanotubes in the potential 0.1 V (SCE). The electrolyte for deposition of Ag nanowires contained 0.5 M AgNO3 and 0.2 M H3BO3; (3) the substrate was dipped into a solution of 1 M NaOH for 3 h to dissolve the AAO template; (4) the superfluous PANI was removed by supersonic and the PANI-Ag NCAs were washed with 0.5 M H2SO4 and stored in 0.2 M H2SO4 solution for further experiments. The length of the PANI-Ag nanocable arrays was 20 mm, and diameter was 100 nm (Fig. 2c).
2.2. Electrochemistry tests and structure characterization Electrochemical preparation and cyclic voltammetry were carried out by using electrochemical workstation (CHI 660b). The AAO/Au substrate serve as the working electrode in a threeelectrode potentiostatic control and direct current (DC) electrodeposition system with a saturated calomel electrode (SCE) as reference electrode, a 1.0 cm 1.0 cm platinum plate as a counter electrode, and a mixed electrolyte of 0.2 M aniline and 0.5 M H2SO4 was used for cyclic voltammetry and capacitor studies on PANI-Ag NCAs. Capacitance was determined from the discharge curves using the equation given below: C ¼It/vm [9], where I is the current (A) used for charge–discharge cycling, t is the time (s), m is the
Fig. 1. Preparation of PANI-Ag nanocable arrays.
Fig. 2. SEM and TEM images of PANI-Ag nanocable arrays.
mass (g) of PANI and v corresponds to potential (V) window of cycling. The morphology of the PANI-Ag NCAs was observed by a scanning electron microscope (SEM, TESCAN 5130SB) and transmission electron microscopy (TEM, Tecnai G2 F20).
3. Results and discussion The SEM image of PANI-Ag NCAs (Fig. 2c) shows that the sample consists of a large quantity of PANI-Ag NCAs, and the nanocables are aligned perpendicularly to the Au layer. Each nanocable has average values dimensions, with approximately length of 20 mm and diameter of 100 nm. The density is about 1010/cm2. Fig. 2a is the TEM image of PANI nanotube. The TEM image (Fig. 2b) shows that the thickness of PANI coated on Ag nanowire is about 0.4 nm. The cyclic voltammogram (CV) of the supercapacitors carried out at a scan rate of 50 mVs 1 is shown in Fig. 3. The CV curve after 1000 cycles is similar to the initial curve which indicates that the electrodes are fairly stable over a long cycle-life. Fig. 4 illustrates the capacitance of PANI-Ag NCAs at different current densities. It is seen that the capacitance values of PANI-Ag NCAs are fairly high at all current densities of cycling, and there is a decrease in capacitance with an increase of current density. The decrease in capacitance is due to a decrease in utilization rate of the amount of PANI with increasing charge–discharge current density. The value reported here is as high as 850 F g 1 which is higher than most of PANI supercapacitors. Moreover, stable long cycle-life, high charge–discharge current densities and low dosage of raw materials make the present system attractive.
4. Conclusion In summary, a novel electrode of PANI-Ag nanocable arrays is fabricated for supercapacitor. PANI-Ag NCAs is prepared by electrodeposition in the pores of the AAO template. The freestanding and vertically aligned PANI-Ag NCAs are uniform. Each PANI-Ag NCAs has average values dimensions, with approximately length of 20 mm and diameter of 100 nm. The density is about 1010/cm2, and the thickness of PANI coating is about 0.4 nm. The capacitance value calculated from a typical experimental data is as high as 850 F g 1 for PANI-Ag NCAs electrodes at 10 mVs 1 sweep rate. The capacitance values of PANI-Ag NCAs are fairly high at all current densities of cycling, and electrodes
Fig. 3. Cyclic voltammograms recorded after 100 and 1000 cycles.
Y. Xie et al. / Materials Letters 86 (2012) 77–79
79
References
Fig. 4. Capacitance of the supercapacitor at different current densities.
are found to be fairly stable over a long cycle-life. The result revealed that the PANI-Ag NCAs could be an ideal alternative to carbon based electrodes, regular conducting polymers and metal oxides for the fabrication of supercapacitor.
[1] Dubal DP, Patil SV, Kim WB, Lokhande CD. Supercapacitors based on electrochemically deposited polypyrrole nanobricks. Mater. Lett. 2011;65:2628–31. [2] Sun W, Chen XY. Fabrication and tests of a novel three dimensional micro supercapacitor. Microelectron. Eng. 2009;86:1307–10. [3] Staiti P, Lufrano F. Investigation of polymer electrolyte hybrid supercapacitor based on manganese oxide-carbon electrodes. Electrochim. Acta 2010;55:7436–42. [4] Sivaraman P, Rath SK, Hande VR, Thakur AP, Patri M, Samui AB. All-solidsupercapacitor based on polyaniline and sulfonated polymers. Synth. Metals 2006;156:1057–64. [5] Gao FL, Zhang LJ, Huang SM. Fabrication horizontal aligned MoO2/singlewalled carbon nanotube nanowires for electrochemical supercapacitor. Mater. Lett. 2010;64:537–40. [6] Wang YHi, Zhitomirsky I. Cathodic electrodeposition of Ag-doped manganese dioxide films for electrodes of electrochemical supercapacitors. Mater. Lett. 2011;65:1759–61. [7] Gong LY, Liu XH, Lu LH. Synthesis of MnO2 nanorods from a ZnO template and their capacitive performances. Mater. Lett. 2012;67:226–8. [8] Song ZX, Xie YJ, Yao SW, Wang HZ, Zhang WG, Tang ZY. Microstructure and magnetic properties of electrodeposited Co/Cu multilayernanowire arrays. Mater. Lett. 2011;65:1562–4. [9] Mondal SK, Keshab Barai, Munichandraiah N. High capacitance properties of polyaniline by electrochemical deposition on a porous carbon substrate. Electrochim. Acta 2007;52:3258–64.