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Silver/Polyaniline Composite Nanotubes: One-Step
Synthesis and Electrocatalytic Activity for
Neurotransmitter Dopamine
Yu Gao, Decai Shan, Fei Cao, Jian Gong,* Xia Li, Hui-yan Ma, Zhong-min Su, and Lun-yu Qu
Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast
Normal UniVersity, Changchun, Jilin 130024, P. R. China
J. Phys. Chem. C 2009, 113, 15175–15181
指導老師 : 陳澄河 教授
研究生 :甘宜婷
報告日期 :
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Introduction
• Recently, the multifunctionality of metal/PANI
composites is particularly useful, which have
attracted considerable attention due to their enhanced
gas sensing properties and electrocatalytic activity,
memory devices.
• Although the composites based on PANI and Ag have
been reported, the preparation for the composites
with nanostructure is still a novel challenge.
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Introduction
• Thus far, dramatic efforts have been dedicated to
develop new methods for the fabrication of Ag/PANI
composite nanostructures in different systems.
• In this paper, they developed a simple self-assembly
polymerization method for the synthesis of highly
uniform and monodisperse Ag/PANI composite
nanotubes without using any acid molecule reagent
and hard template.
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Experiment
0.965 mole APS+8ml DI water
0.117 mole AgNO3
Immobilized for 48 h at 0-5 ℃
0.322 mole苯胺單體
Stirred for 6 h
SEM、EDX、TEM、XPS、
FT-IR 、 UV-vis 、X-ray and
Electrochemical experiments
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Precipitate was washed
with DI water, ethanol,
and ethyl ether
Dried under vacuum
for 24 h at 50℃
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Results and Discussion
-Characterization of Ag/PANI Composite Nanotubes
Figure 1. (A, B) SEM images and (C) TEM image of Ag/PANI composite nanotubes. (D) Corresponding
EDX pattern of the Ag/PANI composite nanotubes. Synthetic conditions: [An], 0.322 mM; [APS], 0.965 mM;
[AgNO3], 0.117 mM; 15 °C; 48 h.
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Figure 2. (A) SEM image and (B) corresponding EDX pattern of pure PANI.
Synthetic conditions: [An], 0.322 mM; [APS], 0.965 mM; 15 °C; 48 h.
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Figure 4. UV-vis spectra of (a) pure PANI and (b) Ag/PANI composite nanotubes.
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Figure 6. XPS spectra of (A) Ag/PANI composite nanotubes, (B) Ag 3d, (C) C 1s, and (D) N 1s.
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Results and Discussion
-Possible Formation of Ag/PANI Composite Nanotubes
• The standard reduction potential of Ag+ + e- →Ag is
E0)+0.79 V, which is lower than 1.02 V of aniline.
Thus, it is hard for AgNO3 to act as an oxidant in the
early stages of aniline polymerization.
• Aniline monomer is oxidized first by APS,
S2O82- + 2e- → 2SO42- (+2.01 V), to form reactive
aniline cation-radicals, simultaneously producing
H2SO4 by the reduction of APS in the early stages.
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• Two initially formed aniline cation-radicals combine
into a dimer which is further oxidized by APS to form
a dimer cation-radical.
• These dimer cation-radicals can act as surfactants to
template the formation of nanotubes under the
condition of excess oxidant.
• Then the Ag anion provided by AgNO3 acts as an
electron acceptor and is reduced to Ag0 while the
dimer cation-radical oxidizes to as-synthesized
resulting PANI.
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• Meanwhile, the dimer cation-radical surfactant
transforms from spherical micelles into tubular
structured micelles for the later formation of the
nanotubes.
• The growth process of the silver nanoparticles and
polymerization of the dimer cation-radical surfactant
continue simultaneously.
• Finally, the PANI nanotubes with dispersed Ag
nanoparticles decorated on the surface are
successfully prepared.
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S2O82- + 2e- → 2SO42- (+2.01 V)
H2SO4
S2O82- + 2e- → 2SO42- (+2.01 V)
Ag+ + e- → Ag (+0.79V)
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Results and Discussion
- Electrochemical Behavior of PANI Composite Nanotubes
Figure 7. CVs of the ITO electrodes modified with (A) Ag/PANI composite nanotubes and
(B) pure PANI in 0.1 M N2-saturated H2SO4 with different scan rates (from inner curve to
outer curve: 10, 20, 30, 40, 50, 60, 80, and 100 mV/s, respectively). Insets show the
relationship of the redox current of peak I and scan rate.
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Figure 8. CVs of ITO electrodes modified with (A) Ag/PANI composite nanotubes and (B)
pure PANI cross-linking as work electrodes in 0.1 M N2-saturated H2SO4 solution containing
DA with various concentrations of 0.0, 0.5, 1.0, 2.0, 3.0, and 4.0 mM (a-f). Scan rate: 50
mV/s.
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Results and Discussion
- Sensitivity Behavior of PANI Composite Nanotubes
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Conclusion
• They successfully prepared Ag/PANI composite
nanotubes by a self-assembly polymerization process
using ammonium persulfate (APS) and silver nitrate
as oxidant.
• Dispersed Ag nanoparticles decorate the surface of
the PANI nanotubes.
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• The Ag/PANI composite nanotubes can be applied to
the chemically modified electrode, which show
enhanced electrocatalytic activity for oxidation of DA
compared with that of the pure PANI-modified
electrode.
• This composite nanomaterial has super gas sensitivity
because of its high surface area, small diameter, and
porous nature of the tubular morphology and the
introduction of the silver nanoparticles.
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