Polypyrrole (PPy) was reinforced with reduced graphene oxide (RGO) and iron oxide to achieve electrochemical stability and enhancement. The ternary nanocomposite film was prepared using a facile one-pot chronoamperometry approach, which is inexpensive and experimentally friendly. The field emission scanning electron microscopy (FESEM) image shows a layered morphology of the ternary nanocomposite film as opposed to the dendritic structure of PPy, suggesting hybridization of the three materials during electrodeposition. X-ray diffraction (XRD) profile shows the presence of Fe2O3 in the ternary nanocomposite. Cyclic voltammetry (CV) analysis illustrates enhanced current for the nanocomposite by twofold and fourfold compared to its binary (PPy/RGO) and individual (PPy) counterparts, respectively. The ternary nanocomposite film exhibited excellent specific capacitance retention even after 200 cycles of charge/discharge. 1. Introduction The increase in affluence in developing countries results in the need of high energy consumption. Therefore, energy sustainability is of significant concern, especially when the depletion of fossil fuels is also factored in. Supercapacitors, also known as ultracapacitors or electrochemical supercapacitors, have several important characteristics, including prolonged life cycle, higher power density than batteries, and higher energy density than conventional capacitors which have driven their use in pulse power and power backup applications. According to the mechanism of charge storage, supercapacitors can be classified as electric double layer capacitors (EDLCs), where charge is stored at the electrode/electrolyte interface, and pseudocapacitors where the charge is stored mainly by Faradaic reactions on the surface of the electrode materials [1]. PPy is an inexpensive and environmentally friendly pseudocapacitor, which has been used due to its excellent properties such as low density, high conductivity, high capacitance value (about 200？Fg？1), and ease in preparation [2, 3]. However, their poor cycling stability, brittleness, and weak tensile strength impede their real applications [4]. Therefore, PPy has been hybridized with EDLC-based carbon materials to overcome the shortcomings [5]. Graphene is an atomically thick, two-dimensional sheet composed of sp2 carbon atoms arranged in a honeycomb structure. It emerges as an intriguing carbon material with potential for electrochemical energy storage device applications due to its superb characteristics of chemical stability, high electrical conductivity, and large surface area [6,
References
[1]
H. N. Lim, N. M. Huang, C. H. Chia, and I. Harrison, “Inorganic nanostructures decorated graphene,” in Advanced Topics in Crystal Growth, Sukarno Ferreira, Ed., InTech, Rijeka, Croatia, 2013.
[2]
P. Saville, “Polypyrrole: formation and use,” Tech. Rep. DRDC-TM-2005-004, Defence Research and Development Atlantic Dartmouth, 2005.
[3]
G. B. Street, T. C. Clarke, R. H. Geiss et al., “Characterization of polypyrrole,” Le Journal De Physique Colloques, vol. 44, pp. 599–606, 1983.
[4]
J. Zhang and X. S. Zhao, “Conducting polymers directly coated on reduced graphene oxide sheets as high-performance supercapacitor electrodes,” Journal of Physical Chemistry C, vol. 116, no. 9, pp. 5420–5426, 2012.
[5]
Y. S. Lim, Y. P. Tan, H. N. Lim et al., “Polypyrrole/graphene composite films synthesized via potentiostatic deposition,” Journal of Applied Polymer Science, vol. 128, pp. 224–229, 2013.
[6]
Z. Sun, D. K. James, and J. M. Tour, “Graphene chemistry: synthesis and manipulation,” The Journal of Physical Chemistry Letters, vol. 2, pp. 2425–2432, 2011.
[7]
Y. Wang, Z. Shi, Y. Huang et al., “Supercapacitor devices based on graphene materials,” Journal of Physical Chemistry C, vol. 113, no. 30, pp. 13103–13107, 2009.
[8]
S. Biswas and L. T. Drzal, “Multilayered nanoarchitecture of graphene nanosheets and polypyrrole nanowires for high performance supercapacitor electrodes,” Chemistry of Materials, vol. 22, no. 20, pp. 5667–5671, 2010.
[9]
N. M. Huang, H. N. Lim, C. H. Chia, M. A. Yarmo, and M. R. Muhamad, “Simple room-temperature preparation of high-yield large-area graphene oxide,” International Journal of Nanomedicine, vol. 6, pp. 3443–3448, 2011.
[10]
Y. S. Lim, Y. P. Tan, H. N. Lim, N. M. Huang, and W. T. Tan, “Preparation and characterization of polypyrrole/graphene nanocomposite films and their electrochemical performance,” Journal of Polymer Research, vol. 20, pp. 1–10, 2013.
[11]
H.-H. Chang, C.-K. Chang, Y.-C. Tsai, and C.-S. Liao, “Electrochemically synthesized graphene/polypyrrole composites and their use in supercapacitor,” Carbon, vol. 50, no. 6, pp. 2331–2336, 2012.
[12]
S. Sahoo, G. Karthikeyan, G. C. Nayak, and C. K. Das, “Electrochemical characterization of in situ polypyrrole coated graphene nanocomposites,” Synthetic Metals, vol. 161, no. 15-16, pp. 1713–1719, 2011.
[13]
A. Davies, P. Audette, B. Farrow et al., “Graphene-based flexible supercapacitors: pulse-electropolymerization of polypyrrole on free-standing graphene films,” Journal of Physical Chemistry C, vol. 115, no. 35, pp. 17612–17620, 2011.
[14]
L. L. Zhang, S. Zhao, X. N. Tian, and X. S. Zhao, “Layered graphene oxide nanostructures with sandwiched conducting polymers as supercapacitor electrodes,” Langmuir, vol. 26, no. 22, pp. 17624–17628, 2010.
[15]
M. B. Sassin, A. N. Mansour, K. A. Pettigrew, D. R. Rolison, and J. W. Long, “Electroless deposition of conformal nanoscale iron oxide on carbon nanoarchitectures for electrochemical charge storage,” ACS Nano, vol. 4, no. 8, pp. 4505–4514, 2010.
[16]
R. A. Fisher, M. R. Watt, and W. J. Ready, “Functionalized carbon nanotube supercapacitor electrodes: a review on pseudocapacitive materials,” ECS Journal of Solid State Science and Technology, vol. 2, pp. 3170–3177, 2013.
[17]
W. Wang, Q. Hao, W. Lei, X. Xia, and X. Wang, “Graphene/SnO2/polypyrrole ternary nanocomposites as supercapacitor electrode materials,” RSC Advances, pp. 10268–10274, 2012.
[18]
B. Ding, X. Lu, C. Yuan et al., “One-step electrochemical composite polymerization of polypyrrole integrated with functionalized graphene/carbon nanotubes nanostructured composite film for electrochemical capacitors,” Electrochimica Acta, vol. 62, pp. 132–139, 2012.
[19]
Y. Xiong, J. Ye, X. Gu, and Q.-W. Chen, “Synthesis and assembly of magnetite nanocubes into flux-closure rings,” Journal of Physical Chemistry C, vol. 111, no. 19, pp. 6998–7003, 2007.
[20]
X.-F. Qu, G.-T. Zhou, Q.-Z. Yao, and S.-Q. Fu, “A spartic-acid-assisted hydrothermal growth and properties of magnetite octahedrons,” Journal of Physical Chemistry C, vol. 114, no. 1, pp. 284–289, 2010.
[21]
Y. S. Lim, Y. P. Tan, H. N. Lim et al., “Potentiostatically deposited polypyrrole/ graphene decorated nano-manganese oxide ternary film for supercapacitors,” Ceramics International, 2013.
[22]
M. D. Stoller and R. S. Ruoff, “Best practice methods for determining an electrode material's performance for ultracapacitors,” Energy and Environmental Science, vol. 3, no. 9, pp. 1294–1301, 2010.
