Article

Synthesis and characterization of RuO(2)/poly(3,4-ethylenedioxythiophene) composite nanotubes for supercapacitors.

Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
Physical Chemistry Chemical Physics (impact factor: 3.57). 05/2010; 12(17):4309-16. DOI:10.1039/b918589p pp.4309-16
Source: PubMed

ABSTRACT We report the synthesis of composite RuO(2)/poly(3,4-ethylenedioxythiophene) (PEDOT) nanotubes with high specific capacitance and fast charging/discharging capability as well as their potential application as electrode materials for a high-energy and high-power supercapacitor. RuO(2)/PEDOT nanotubes were synthesized in a porous alumina membrane by a step-wise electrochemical deposition method, and their structures were characterized using electron microscopy. Cyclic voltammetry was used to qualitatively characterize the capacitive properties of the composite RuO(2)/PEDOT nanotubes. Their specific capacitance, energy density and power density were evaluated by galvanostatic charge/discharge cycles at various current densities. The pseudocapacitance behavior of these composite nanotubes originates from ion diffusion during the simultaneous and parallel redox processes of RuO(2) and PEDOT. We show that the energy density (specific capacitance) of PEDOT nanotubes can be remarkably enhanced by electrodepositing RuO(2) into their porous walls and onto their rough internal surfaces. The flexible PEDOT prevents the RuO(2) from breaking and detaching from the current collector while the rigid RuO(2) keeps the PEDOT nanotubes from collapsing and aggregating. The composite RuO(2)/PEDOT nanotube can reach a high power density of 20 kW kg(-1) while maintaining 80% energy density (28 Wh kg(-1)) of its maximum value. This high power capability is attributed to the fast charge/discharge of nanotubular structures: hollow nanotubes allow counter-ions to readily penetrate into the composite material and access their internal surfaces, while a thin wall provides a short diffusion distance to facilitate ion transport. The high energy density originates from the RuO(2), which can store high electrical/electrochemical energy intrinsically. The high specific capacitance (1217 F g(-1)) which is contributed by the RuO(2) in the composite RuO(2)/PEDOT nanotube is realized because of the high specific surface area of the nanotubular structures. Such PEDOT/RuO(2) composite nanotube materials are an ideal candidate for the development of high-energy and high-power supercapacitors.

0 0
 · 
0 Bookmarks
 · 
65 Views
  • Source
    Article: Redox exchange induced MnO2 nanoparticle enrichment in poly(3,4-ethylenedioxythiophene) nanowires for electrochemical energy storage.
    Ran Liu, Jonathon Duay, Sang Bok Lee
    [show abstract] [hide abstract]
    ABSTRACT: MnO2 nanoparticle enriched poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires are fabricated by simply soaking the PEDOT nanowires in potassium permanganate (KMnO4) solution. The structures of these MnO2 nanoparticle enriched PEDOT nanowires are characterized by SEM and TEM, which show that the MnO2 nanoparticles have uniform sizes and are finely dispersed in the PEDOT matrix. The chemical constituents and bonding of these composite nanowires are characterized by energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and infrared spectroscopy, which indicate that the formation and dispersion of these MnO2 nanoparticles into the nanoscale pores of the PEDOT nanowires are most likely triggered by the reduction of KMnO4 via the redox exchange of permanganate ions with the functional group on PEDOT. Varying the concentrations of KMnO4 and the reaction time controls the loading amount and size of the MnO2 nanoparticles. Cyclic voltammetry and galvanostatic charge-discharge are used to characterize the electrochemical properties of these MnO2 nanoparticle loaded PEDOT nanowires. Due to their extremely high exposed surface area with nanosizes, the pristine MnO2 nanoparticles in these MnO2 nanoparticle enriched PEDOT nanowires show very high specific capacitance (410 F/g) as the supercapacitor electrode materials as well as high Li+ storage capacity (300 mAh/g) as cathode materials of Li ion battery, which boost the energy storage capacity of PEDOT nanowires to 4 times without causing excessive volume expansion in the polymer. The highly conductive and porous PEDOT matrix facilitates fast charge/discharge of the MnO2 nanoparticles and prevents them from agglomerating. These synergic properties enable the MnO2 nanoparticle enriched PEDOT nanowires to be promising electrode materials for supercapacitors and lithium ion batteries.
    ACS Nano 07/2010; 4(7):4299-307. · 10.77 Impact Factor
  • Source
    Article: Electrochemical formation mechanism for the controlled synthesis of heterogeneous MnO2/Poly(3,4-ethylenedioxythiophene) nanowires.
    Ran Liu, Jonathon Duay, Sang Bok Lee
    [show abstract] [hide abstract]
    ABSTRACT: The formation mechanism of a coaxial manganese oxide/poly(3,4-ethylenedioxythiophene) (MnO(2)/PEDOT) nanowire is elucidated herein by performing electrodeposition of MnO(2) and PEDOT on Au-sputtered nanoelectrodes with different shapes (ring and flat-top, respectively) within the 200 nm diameter pores of an anodized aluminum oxide (AAO) template. It is found that PEDOT prefers to grow on the sharp edge of the ring-shaped electrode, while MnO(2) is more likely to deposit on the flat-top electrode due to its smooth surface. The formation of coaxial nanowires is shown to be a result of simultaneous growth of core MnO(2) and shell PEDOT by an analysis of the current density resulting from electrochemical deposition. Furthermore, the structures of the MnO(2)/PEDOT coaxial nanowires were studied for their application as supercapacitors by modifying their coelectrodeposition potential. A potential of 0.70 V is found to be the most favorable condition for synthesis of MnO(2)/PEDOT coaxial nanowires, resulting in a high specific capacitance of 270 F/g. Additionally, other heterogeneous MnO(2)/PEDOT nanostructures are produced, such as nanowires consisting of MnO(2) nanodomes with PEDOT crowns as well as segmented MnO(2)/PEDOT nanowires. This is accomplished by simply adjusting the parameters of the electrochemical deposition. Finally, in smaller diameter (50 nm) AAO channels, MnO(2) and PEDOT are found to be partially assembled into coaxial nanowires due to the alternative depletion of Mn(II) ions and EDOT monomers in the smaller diameter pores.
    ACS Nano 06/2011; 5(7):5608-19. · 10.77 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Full-text

View
0 Downloads
Available from

Keywords

80% energy density
 
composite material
 
composite nanotubes
 
composite RuO(2)/PEDOT nanotube
 
composite RuO(2)/PEDOT nanotubes
 
composite RuO(2)/poly(3,4-ethylenedioxythiophene)
 
current collector
 
fast charging/discharging capability
 
flexible PEDOT
 
galvanostatic charge/discharge cycles
 
high-power supercapacitors
 
hollow nanotubes
 
ideal candidate
 
PEDOT nanotubes
 
porous alumina membrane
 
porous walls
 
power capability
 
power density
 
RuO(2)/PEDOT nanotubes
 
step-wise electrochemical deposition method