Electrochemical synthesis, characterization and capacitive properties of novel thiophene based conjugated polymer

Article abstract of DOI:10.1016/j.reactfunctpolym.2014.07.014

In this paper, a novel thiophene based monomer, 1-(pyren-1-yl)-2,5- di(thiophen-2-yl)-1H-pyrrole, PThP, was synthesized and characterized by ¹H NMR and ¹³C NMR spectroscopic methods. The electrochemical behavior and electropolymerization of this novel monomer were performed on pencil graphite electrode (PGE) by cyclic voltammetry. The effect of solvent, dopant, scan number and scan rate on the electropolymerization and properties of the conjugated polymer films were investigated. The capacitive properties of the poly(PThP) films were tested by electrochemical impedance spectroscopy (EIS). The highest specific capacitance value was calculated for the conjugated polymer modified PGE that was obtained in 0.1 M tetrabutylammonium perchlorate/dichloromethane solution for 30 cycles at 25 mV/s scan rate as 25.45 mF cm^-2. The surface morphologies of the conjugated polymer modified electrodes were determined by scanning electron microscopy (SEM).

Full text of DOI:10.1016/j.reactfunctpolym.2014.07.014

Reactive & Functional Polymers 83 (2014) 107–112
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Reactive & Functional Polymers
journal homepage: www.elsevier.com/locate/react
Electrochemical synthesis, characterization and capacitive properties of
novel thiophene based conjugated polymer
a
a
b
a
c,
b
d
⇑
_
Burcu Çelik , Ilhami Çelik , Hacer Dolaßs , Hakan Görçay , Yücel Sßahin , A. Sezai Saraç , Kadir Pekmez
a Faculty of Science, Department of Chemistry, Anadolu University, 26470 Eskißsehir, Turkey
b Polymer Science and Technology, Department of Chemistry, Istanbul Technical University, 34469 Istanbul, Turkey
c Faculty of Arts & Science, Department of Chemistry, Yildiz Technical University, 34210 Istanbul, Turkey
d Faculty of Science, Department of Chemistry, Hacettepe University, 06532 Ankara, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
In this paper, a novel thiophene based monomer, 1-(pyren-1-yl)-2,5-di(thiophen-2-yl)-1H-pyrrole, PThP,
was synthesized and characterized by 1H NMR and 13C NMR spectroscopic methods. The electrochemical
behavior and electropolymerization of this novel monomer were performed on pencil graphite electrode
(PGE) by cyclic voltammetry. The effect of solvent, dopant, scan number and scan rate on the electropo-
lymerization and properties of the conjugated polymer films were investigated. The capacitive properties
of the poly(PThP) films were tested by electrochemical impedance spectroscopy (EIS). The highest spe-
cific capacitance value was calculated for the conjugated polymer modified PGE that was obtained in
0.1 M tetrabutylammonium perchlorate/dichloromethane solution for 30 cycles at 25 mV/s scan rate as
25.45 mF cmꢀ2. The surface morphologies of the conjugated polymer modified electrodes were deter-
mined by scanning electron microscopy (SEM).
Received 6 November 2013
Received in revised form 25 June 2014
Accepted 5 July 2014
Available online 21 July 2014
Keywords:
Thiophene
Cyclic voltammetry
Electropolymerization
Electrochemical impedance spectroscopy
Supercapacitor
Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction
tors in which electroactive materials are used such as insertion type
compounds (e.g. RuO2, NiO, etc.) or conjugated polymers (CPs) [4].
Electrochemical capacitors, often called supercapacitors, elec-
trical double-layer capacitors, pseudocapacitances or ultracapaci-
tors have attracted worldwide research interest because of their
potential applications as energy storage devices in many fields
[1]. The enormous progress in supercapacitor technology, resulting
in electrode materials with higher and higher specific capacitance
values, has led to extension of their application [2]. Supercapaci-
tors can store more energy than a conventional capacitor because:
(i) charge separation takes place across a very small distance in the
electrical double layer that constitutes the inter phase between
electrode and electrolyte; and (ii) an increased amount of charge
can be stored on the highly extended electrode surface area created
by a large number of pores within an electrode material. The mech-
anism of energy storage is naturally rapid because it simply
involves movement of ions to and from electrode surfaces [3].
On the basis of electrode materials used and the charge storage
mechanisms, electrochemical supercapacitors are classified as: (a)
electrical double-layer capacitors which employ carbon or other
similar materials as blocking electrodes and (b) redox supercapaci-
These organic polymers possess conductive chain structures and
electrical conductivity [5]. The conjugated polymers of unique
properties such as mechanical strength, electrical conductivity,
remarkable stability and possibility of both chemical and electro-
chemical synthesis and low bandgap, have received great attention.
Therefore, they are used in potential applications in various emerg-
ing fields such as transparent electrodes, OLEDs, rechargeable bat-
teries, electrochromic displays and smart windows, light emitting
diodes, sensors, corrosion inhibitors, field effect transistors (FETs),
electromagnetic interference (EMI) shielding and electrochemical
supercapacitors, etc. [6–9]. CPs are promising materials for the real-
ization of high performance supercapacitors, as they are character-
ized by high specific capacitances and by high conductivities in the
charged states. Furthermore, their charge–discharge processes are
generally fast. These features suggest the possibility to develop
devices with low equivalent series resistance (ESR) and high spe-
cific energy and power [10].
Electrochemical synthesis of conjugated polymers has some
advantages. For instance, it permits the synthesis without using
oxidizing agent together with doping with different organic and
inorganic ions. In addition, it is a simple and relatively inexpensive
method. By adjusting the conditions, both powders and films can
be obtained and also this allows controlling thickness [11,12]. In
⇑
Corresponding author. Tel.: +90 212 3834132; fax: +90 212 3834134.
E-mail address: yucelsahin06@gmail.com (Y. Sßahin).
http://dx.doi.org/10.1016/j.reactfunctpolym.2014.07.014
1381-5148/Ó 2014 Elsevier Ltd. All rights reserved.

108
B. Çelik et al. / Reactive & Functional Polymers 83 (2014) 107–112
the electropolymerization process of the conducting polymers, two
oxidation reactions occur simultaneously. The oxidation of mono-
mers and oligomers and the oxidation of a polymer form on the
electrode surface producing positive charges (polarons and/or
bipolarons). The positive charges are compensated by the anions
such as chloride, perchlorate, sulfonate, in the electrolyte solution
which is called doping process [13]. In this process, it is possible to
control the electrical conductivity of polymer over the range from
insulating to highly conducting state. In addition simple modifica-
tions of the experimental parameters, e.g. changing the electrode
material or solvent, result in changes in the electropolymerization
process and in the properties of the final film [14].
S
N
S
Pyrrole, aniline, thiophene and their derivatives can be poly-
merized to get conjugated polymers by electrochemical synthesis
[15]. Electrodeposition of conductive polythiophene (PTh) films
by electrochemical oxidation of thiophene and its derivatives has
been widely described in recent years [16]. Polythiophenes and
their derivatives present an important class of conjugated poly-
mers that form some of the most environmentally and thermally
stable materials in both doped and undoped states. These polymers
have various useful properties like having high-charge carrier
mobilities and high thermal and photochemical stability. In addi-
tion, they easily form relatively stable radical cations (holes)
[17,18]. PTh and its derivatives are one of the most promising sup-
ercapacitor materials and has received a significant amount of
attention in applications [19].
Scheme 1. The chemical structure of 1-(pyren-1-yl)-2,5-di(thiophen-2-yl)-1H-
pyrrole.
mesh. Dichloromethane (HPLC grade, 99.9%) and acetonitrile (HPLC
grade, 99.9%) were purchased from Sigma–Aldrich. All chemicals
were analytical grade reagents and were used without further puri-
fication. Tetrabutylammonium tetrafluoroborate (TBABF4) (>99%),
tetrabutylammonium perchlorate (TBAP) (>99%) and tetrabutylam-
monium hexafluorophosphate (TBAPF6) (>99%) were obtained
from Fluka.
2.2. Synthesis of PThP
Carbon in its dispersed and conducting form is the most widely
used commercial material for electrochemical supercapacitors
applications as an electrode material. Among carbon based materi-
als, PGE can be seen an important electrode material due to its large
active electrode surface area, high electrochemical reactivity, good
mechanical rigidity, low cost, disposable and wide potential win-
dow. It can be also easily modificated and miniaturized. A combina-
tion of conjugated polymers and carbon for positive and negative
electrodes in supercapacitors is both scientifically and commer-
cially applicable due to the low cost of the two materials [20–22].
EIS is an attractive method to study the electrical behavior of
coated and uncoated neutral prosthetic devices. It involves mea-
suring the electrode impedance over a spectrum of frequencies.
By using magnitude and phase information data, one can obtain
qualitative and quantitative information about the electrical prop-
erties of the coated and uncoated electrodes. Interesting informa-
tion can be obtained concerning potential distribution across the
interface, doping level, solution resistance, carrier recombination
and generation at the surface and in the space region. To determine
the magnitude of the resistive and capacitive response, their per-
formance can be examined in a wide range of frequencies [23,24].
In this work, a novel thiophene derivative, 1-(pyren-1-yl)-2,5-
di(thiophen-2-yl)-1H-pyrrole, PThP, (Scheme 1) was synthesized
by a chemical method and electropolymerized on PGE as an elec-
trode material for supercapacitor applications for the first time in
this work. The effect of solvent, dopant ions, scan rate and scan
number on electropreparation and properties of the poly(PThP)
films were investigated. 1H NMR and 13C NMR spectroscopic meth-
ods were used to characterize the PThP. The properties of the poly-
mer were studied in detail using cyclic voltammetry. The
capacitive properties of the modified poly(PThP)/PGEs were tested
by electrochemical impedance spectroscopy. The surface morphol-
ogy of conjugated poly(PThP) films was investigated by SEM.
1,4-di(thiophene-2-yl)butane-1,4-dione was synthesized
according to literature procedure [25]. A solution of 500 mg
(2 mmol) 1,4-di(thiophen-2-yl)butane-1,4-dione, 434 mg (2 mmol)
1-aminopyrene and catalytic amount of p-toluenesulfonic acid
(p-TsOH) in dry toluene were refluxed in a Dean–Stark apparatus
until all the starting materials were disappeared on TLC. The flask
was cooled and the solvent was removed under reduced pressure.
The residue was placed in a silica-gel column with dichloromethane
(CH2Cl2) to give the pure PThP monomer. Synthesis route of the
PThP is shown in Scheme 2.
NMR spectra were recorded on a Bruker Advance 500 DPX spec-
trometer (1H at 500 MHz and 13C at 125 MHz) in chloroform-d
(CDCl3) with tetramethylsilane (TMS) as the internal standard.
2.2.1. 1-(pyrene-6-yl)-2,5-di(thiophen-2-yl)-1H-pyrrole
Yield 64%; Orange solid; Mp = 244–246 C. 1H NMR (500 MHz,
CDCl3): d 6.39 (s, 2H), 6.58 (s, 2H), 6.80 (br, s, 4H), 7,61 (d, J = 8.5,
1H), 8.06 (m, 3H), 8.21 (m, 3H), 8.28 (t, J = 9.5, 2H), 13C NMR
(125 MHz, CDCl3):
d 109.75, 122.10, 123.64, 123.68, 124.40,
124.90, 125.05, 125.92, 126.52, 126.73, 127.28, 128.06, 128.59,
129.34, 130.75, 130.96, 131.10, 131.48, 132.07, 132.11.
O
Cl
AlCl3
2
Cl
CH2Cl2/reflux
S
S
S
O
O
O
1-aminopyrene
-TsOH
Toluene(110oC)
p
N
S
S
2. Experimental
2.1. Materials
Glassware was routinely oven-dried at 110 °C for a minimum of
4 h. Column chromatography was performed on silica-gel 70–230
Scheme 2. The synthesis route of the PThP.

B. Çelik et al. / Reactive & Functional Polymers 83 (2014) 107–112
109
0.0016
0.0014
0.0012
0.0010
0.0008
0.0006
0.0004
0.0002
0.0000
2.3. Electropolymerization and cyclic voltammetry
Electropolymerization of PThP was performed on the surface of
PGE by cyclic voltammetry at ambient conditions. Three electrode
system was used for all measurements; pencil graphite and plati-
num electrodes as the working electrodes and a Pt auxiliary elec-
trode. All measurements were carried out with an Ag/AgCl
reference electrode.
A Noki pencil model 2000 (Japan) was used as a holder for
graphite leads (Tombo, HB, 0.5 mm diameter, Japan). Electrical
contact with the lead was obtained by soldering a metallic wire
to the metallic part. PGEs were washed with water and dichloro-
methane to remove the impurity and dried at room temperature
before the experiments. Then, PGE was immersed in the polymer-
ization solution. The poly(PThP) was obtained by electrodeposition
on the surface of the working electrodes in dichloromethane and
acetonitrile solutions of 0.1 M TBABF4, TBAP and TBAPF6 with
0.01 M PThP. Electrochemical studies were performed with a Auto-
lab PGSTAT 100 potentiostat–galvanostat controlled by a GPES 4.9
software (Ecochemie, The Netherlands).
0.000 0.008 0.016 0.024 0.032 0.040 0.048
Concentration (M)
Fig. 1. The effect of PThP concentration on the yield of electropolymerizations.
2.4. Electrochemical impedance spectroscopy (EIS)
EIS measurements were performed at room temperature using
a conventional three electrode cell configuration. In all impedance
measurements, PGE was used as working electrode, platinum wire
was used as counter electrode, and Ag wire was used as reference
electrode. The electrochemical cell was connected to a potentiostat
(PARSTAT 2263) interfaced to a computer. The electrochemical
impedance software PowerSine was used to carry out impedance
measurements scanning in the frequency range between 10 MHz
and 100 kHz with an applied AC signal amplitude of 10 mV.
Fig. 2. The five initial cyclic voltammograms of 0.01 M PThP in a dichloromethane
solution containing 0.1 M TBAP. The scan rate was 75 mV/s.
2.5. Morphological analysis
bare PG working electrode. The formation and growth of the poly-
mer film can easily be seen in this figure suggested that the films
were conductive and electroactive [16]. The oxidation and reduc-
tion peaks of the film increase in intensity as the film grows. There
are one broad oxidation and reduction peaks observed during the
growth of the film. The oxidation peak was observed at the peak
potential of +1.04 V with corresponding cathodic peak at +0.60 V
belonging to the reverse process.
The morphological features of the electrocoated electrodes
were performed with scanning electron microscope (SEM). The
pencil graphite electrodes were attached on a metal holder by
use of a double sided carbon type. SEM measurements were carried
out via Zeiss-Ultraplus.
3. Results and discussion
The effect of electrode type on the electropolymerization of
PThP (0.01 M) was investigated. The films were grown on a Pt plate
and a PGE in a dichloromethane electrolyte solution containing of
0.1 M TBAP by cycling of the potential between ꢀ0.30 to +1.90 V
(vs. Ag/AgCl) at a scan rate of 100 mV/s. Fig. 3 shows the results
of such a comparison. The reduction peak obtained during the
growth of the polymer on the surface of PGE shifted to more catho-
dic potentials according to Pt electrode as the scan number
increases. This result may indicate that higher polymer chains
are formed on the surface of PGE [26]. Due to the nature of two dif-
ferent electrodes, the bonding of polymer onto PGE would be easier
than on Pt. This may also influence the kinetics of polymerization
leading to a shift in peak potential, with a greater shift for the
PGE electrode than the Pt electrode being expected.
The modified electrodes prepared electrochemically were
immersed in dichloromethane to remove monomer and the soluble
oligomers formed during electropreparation of the film and then
vacuum dried. The electrochemical behavior of the modified elec-
trodes in monomer free electrolyte solutions containing different
types of dopants at different scan rates are shown in Fig. 4. The
modified film electrodes did not lose their electroactivity and exhi-
bit broad oxidation and reduction peaks in monomer free electro-
lyte solutions.
3.1. Electropolymerization and characterization
To determine the effect of monomer concentration on the yield
of electropolymerization, the poly(PThP) films were grown in
solutions of varying PThP concentrations in the range of
10–4 M–5 ꢁ 10–2 M on a Pt plate electrode by the cycling of the
potential between ꢀ0.3 and 1.9 V (vs. Ag/AgCl) for the same cycles.
0.1 M TBAP was used as the supporting electrolyte in the electropo-
lymerization. Solubility of PThP decreased with increasing amount
of PThP in acetonitrile solutions. Therefore, dichloromethane was
used as a solvent in the electropolymerization of PThP. The opti-
mum PThP concentration was found to be 0.01 M (Fig. 1). There
was a considerable decrease in the yield of polymer formation
below and above this PThP concentration. It can be concluded that
the optimum monomer concentration under these conditions was
about 0.01 M.
Fig. 2 shows the initial five cyclic voltammetric sweeps taken
during the oxidation of 0.01 M PThP in 0.1 M TBAP/dichlorometh-
ane solution. The potential was scanned from ꢀ0.30 to +1.90 V
(vs. Ag/AgCl) at a scan rate of 75 mV/s. The oxidation peak of the
PThP shifts to higher anodic potentials. It shows the formation of
a film on the electrode surface and behaves different from that of

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B. Çelik et al. / Reactive & Functional Polymers 83 (2014) 107–112
5:4 and 3:2 for TBAPF6:TBABF4, respectively. These results indicate
that the electrochemical polymer growth rate ratio was faster in
TBAPF6 than the others.
3.3. Surface morphology
Dielectric, electrical, and mechanical properties, the film forma-
tion and surface morphology of conducting polymers are affected
by various parameters: such as nature of solvent and dopant anion,
solution pH, temperature, synthesis method, scan rate. Poor con-
trol of these parameters will result in dendritic morphology. Den-
dritic surface will cause interfacial problems in electronic device
applications, such as Schottky junctions, and also introduce large
errors into the direct current (DC) conductivity measurements by
the four probe method due to the errors in polymer thickness
determination [27–29]. Therefore, polymer films were deposited
from 0.01 M solution of the PThP on to PGE by cyclic voltammetry
at different scan rates, dopants and scan numbers to investigate
their effect on the morphology of the polymer film. Their morphol-
ogies were monitored using SEM. As shown in Fig. 6(a) and (b) and
(e) and (f) the thickness of the polymer film is a function of cycle
number and scan rate. The film thickness increases linearly with
increasing of the number of cycle numbers and decrease linearly
with increasing of the scan rate. In Fig. 6(b), it is clearly showed
that the surface of the graphite electrode was not completely cov-
ered with the polymer. When Fig. 6(e) is compared with Fig. 6(f),
small grains are formed on the electrode surface in low cycle num-
bers. This also explains why we could not obtain high capacitances
values for the polymers deposited at low number of cycle. The
effects of different dopant anions on the morphology of the film
are shown in Fig. 6(c) and (d).
Fig. 3. Cathodic peak potential shifts vs. scan number for solutions of monomer on
pencil graphite and Pt electrodes in 0.1 M TBAP/dichloromethane solution at
100 mV/s scan rate.
3.2. Effect of dopant ions
To determine the effect of different dopant ions on the growth
of the polymer film, the films were grown in dichloromethane
solutions containing 0.1 M TBABF4, TBAP and TBAPF6 by cycling
the potential between ꢀ0.30 and +1.90 V with different scan num-
bers. Fig. 5 shows the change in anodic and cathodic peak currents
of monomers during the electropolymerization in these electro-
lytes solutions at the scan rate of 100 mV/s. The anodic and catho-
dic peak currents were measured during the electro-oxidation of
the monomer. The different slopes, dI/dt, were obtained in different
supporting electrolytes corresponding to the growth rate of poly-
mer film on the PGE surface. As shown in Fig 5, the growth of
the polymer film was not regular in TBAP/dichloromethane solu-
tion. The anodic and cathodic peak currents ratios of slopes were
3.4. Electrochemical impedance spectroscopy measurements
EIS was performed to monitor electrochemical behavior of the
composite electrodes. EIS is believed to be a good technique for
decoupling the electrochemical and mass-transport processes in
Fig. 4. The electrochemical behavior of the poly(PThPs) in monomer free dichloromethane solutions of (a) 0.1 M TBAPF6, (b) TBABF4 and (c) TBAP at different scan rates: 25,
50, 100, 200, 400 mV/s.

B. Çelik et al. / Reactive & Functional Polymers 83 (2014) 107–112
111
Table 1
The capacitance values of the polymer films which synthesized in different scan
numbers and scan rates.
Scan rate (mV/s)
Scan number
10 (F)
20 (F)
30 (F)
25
50
75
1.712 ꢁ 10–3
3.829 ꢁ 10–3
2.732 ꢁ 10–3
3.523 ꢁ 10–3
5.031 ꢁ 10–3
3.579 ꢁ 10–3
5.157 ꢁ 10–3
2.978 ꢁ 10–3
6.044 ꢁ 10–3
4.413 ꢁ 10–3
4.309 ꢁ 10–3
3.195 ꢁ 10–3
100
scan rates were calculated from the Nyquist diagrams. The highest
capacitance values as 6.044 mF were detected for the polymer that
was obtained in 0.1 M TBAP/dichloromethane solution for 30 cycles
at 25 mV/s scan rate (Table 1). 1.5 cm of the PGE was dipped into
the solution to keep the electrode area constant (ꢂ0.2375 cm2).
According to EIS measurements, modified PGE has shown the spe-
cific capacitance of 25.45 mF cmꢀ2 at 25 mV sꢀ1 scan rate and 30
cycles in 0.1 M TBAP/dichloromethane electrolyte solution.
Fig. 5. The anodic and cathodic peak currents of poly(PThPs) during polymer
growth.
the redox mechanisms of polymers and studying capacitance value
of modified electrodes [30,31].
For DC measurements, Ohm’s law, V = IR, is used the describe
relationship between voltage, current and resistance. For AC mea-
surements, Ohm’s law is changed to V = IZ, where the impedance Z,
is used rather than resistance in order to allow for frequency
dependence and phase shifts between stimulus and observed
response. Such properties do not occur in resistors, which have
an impedance equation of Z = R [32]. Instead of resistance, imped-
ance is used in electrochemical system because it is a more general
circuit parameter. Like resistance, impedance is a measure of the
ability of an equivalent circuit to resist the flow of electrical cur-
rent. Different from resistance, impedance is not limited by the
properties of the ideal resistor The expression Z is composed of a
real (Zre) and an imaginary part (Zim). The standard impedance plot
used to characterize a conducting polymer is the Nyquist plot on
which the real part is plotted on the X-axis and the imaginary part
on the Y-axis of a chart. [33].
In the literature, different electrode materials were used for sup-
ercapacitor applications. Among these materials, poly[3,4-(2,2-dim-
ethylpropylenedioxythiophene)] was electropolymerized on
a
bundle of carbon fiber microelectrodes (CFMEs) and reported a
low frequency capacitance value of 12.05 mF cmꢀ2. Using a standard
three electrode system in sodium perchlorate (NaClO4)/ACN at open
circuit potential a double layer capacitance value of 14.4 mF cmꢀ2
was reported. For exfoliated carbon fibers (ExCFs) capacitances of
117–450 F gꢀ1 at surface areas from 330 to 300 m2 gꢀ1 were
mentioned. These values are equivalent to 0.035–0.15 mF cmꢀ2
.
3,4-(2,2-dibutylpropylenedioxy)thiophene (ProDOT-Bu2) was elec-
trodeposited onto single carbon fiber microelectrode (SCFME) and
calculated specific capacitance value as 62 mF cmꢀ2 in ACN electro-
lyte solution containing NaClO4 as dopant [35]. These results have
shown that poly(PThP)/PGE has much higher specific capacitance
than other modified electrodes just expect the modified 3,4-(2,2-
dibutylpropylenedioxy)thiophene SCFME.
It is well known that if the phase angle is greater or equal to 90°,
the modified electrode behaves like an ideal capacitor. On the other
hand, if the phase angle is less than 90° then the modified electrode
is easily allowing the ions from solution. It can be seen in Fig. 7(b)
that the values of phase angles for the polymer film is less than 90°
and thus the polymer film is not behaved like an ideal capacitor
[30].
The low frequency capacitance values of the polymer film at
0.01 Hz and 100 kHz from impedance spectroscopy were obtained
from the slop of a plot of imaginary component (Zim) of the imped-
ance at low frequencies versus inverse of the reciprocal frequency
(f: 0.01 Hz) using following equation [34]:
Csp ¼ ð2
p
fZimÞꢀ1
ð1Þ
The specific capacitance values of the polymers, which are
electrodeposited in the different dopant ions, cycle numbers and
Fig. 6. SEM images of the polymer films deposited by cyclic voltammetry with a same monomer concentration (0.01 M); change number of cycles, different scan rates and
dopants: (a) 30 cycle, 25 mV/in TBAPF6, (b) 30 cycle, 100 mV/s in TBAPF6, (c) 30 cycle, 25 mV/s in TEABF4, (d) 30 cycle, 25 mV/s in TBAPF6, (e) 30 cycle, 25 mV/s in TBAP and
(f) 10 cycle, 25 mV/s in TBAP.

112
B. Çelik et al. / Reactive & Functional Polymers 83 (2014) 107–112
60
a
b
50
40
30
20
10
0
800
400
0
1E-3
0.01
0.1
1
10
100
1000 10000 100000 1000000
1000
2000
3000
freq (hz)
Zre (ohm)
Fig. 7. (a) Nyquist and (b) Bode plots of the polymer film on the graphite electrode in 0.1 M TBAP/dichloromethane solution.
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A novel thiophene derivative, 1-(pyren-1-yl)-2,5-di(thiophen-
2-yl)-1H-pyrrole, PThP, was synthesized by chemical method and
electropolymerized on the surface of PGE for the first time in this
work. 1H NMR and 13C NMR spectroscopies were used to character-
ize the PThP. The effect of solvent, dopant ions, scan rate and scan
number on the electropreparation and properties of the poly(PThP)
films were investigated. The properties of the polymer were stud-
ied using cyclic voltammetry and scanning electron microscopy
techniques. The SEM pictures show that the electropolymerization
of monomer was successfully occured on the surface of PGEs. Cyc-
lic voltammograms indicate that the choice of dopant ions has
influenced on the electropolymerization process. In addition, the
influences of scan rate, cycle number and dopant ions on the mor-
phology of polymer film are clearly shown in the SEM images. The
capacitive properties of the poly(PThP) films were tested by elec-
trochemical impedance spectroscopy. The highest specific capaci-
tance value was obtained for the polymer that was synthesized
in TBAP/dichloromethane solution with 25 mV/s scan rate and 30
cycles as 25.45 mF cmꢀ2. As a result, this modified PGE can be used
as an electrode material for supercapacitors in the low voltage
applications.
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