-
Electrochimica Acta 85 (2012) 42 48
Contents lists available at SciVerse ScienceDirect
Electrochimica Acta
jou rn al h om epa ge: www.elsev ier .com
Green ell-nanoco e resorci
Li Zaijun juna School of Cheb School of Fooc National Univd
Zhejiang Zany
a r t i c l
Article history:Received 18 February 2012Received in revised
form 24 July 2012Accepted 22 August 2012Available online 30 August
2012
Keywords:GrapheneGoldNanocompositSensing materElectrodeposit
The paper described a green and controllable strategy to
fabricate well-dispersed graphenegoldnanocomposite lm. To prepare
graphenegold nanocomposite lm, graphene and gold nanoparticleswere
alternately electrodeposited on the surface of glassy carbon
electrode. Since electrochemical tech-nique offers control over
reaction parameters and excellent repeatability, the amounts of
graphene andgold nanoparticles for the each layer can be
pre-determined by controlling concentrations of graphene
1. Introdu
Graphentopic in meffective stthe integratially pavesand
electronanocompomicrowavetures of grause of highlposites, maapplied
to tFor exampl
CorresponE-mail add
0013-4686/$ http://dx.doi.oe lmialsion
oxide and chlorauric acid. The as-prepared graphenegold
nanocomposite lm was characterized byinfrared spectrum, scanning
electron microscope, Raman spectrum and X-ray diffraction, and its
elec-trocatalytic activity was estimated by Lavirons model. The
apparent heterogeneous electron transferrate constant of 37.67 0.19
cm s1 was obtained, indicating fast electron transfer of Fe(CN)64
to theelectrode. Further, the lm was investiaged as sensing
materials for synchronously detection of hydro-quinone and
resorcinol. When the cencentrations are in the ranges of 1.6 108 to
1.2 104 mol l1for hydroquinone and 1.0 108 to 2 106 mol l1 for
resorcinol, differential pulse voltammetric peakcurrent of the
sensor linearly increases. The sensitivities of differential pulse
voltammetric response are30.5 A M1 cm2 for hydroquinone and 117.83
A M1 cm2 for resorcinol. The detection limits werefound to be 5.2
109 mol l1 for hydroquinone and 2.2 109 mol l1 for resorcinol (S/N
= 3). Proposedmethod is simple, sensitive and selective, it has
been applied to the determination of hydroquinone andresorcinol in
real water samples with a spiked recovery in the range of
96.0103.4%.
2012 Published by Elsevier Ltd.
ction
emetal nanocomposite has become a hot researchaterial science
because the hybridization can be anrategy to enhance the
functionality of materials, andtion of nanomaterials on graphene
nanosheets poten-
a new way to enhance their electronic, chemical,chemical
properties [14]. Typically, graphenemetalsite was prepared by
chemical [5,6], thermal [7,8],
[9,10] or solvothermal [11,12] reduction of the mix-pheme oxide
(GO) and metallic precursor. To avoid they toxic chemicals and
improve dispersivity of the com-ny environmentally friendly
reducing agents have beenhe fabrication of graphenemetal
nanocomposites [13].e, Tian and co-workers reported that
-cyclodextrin
ding author. Tel.: +86 5105811863; fax: +86 5105811863.ress:
[email protected] (L. Zaijun).
was empolyed for in situ thermal reduction of graphene oxide
andchlorauric acid. In essence, GO, -cyclodextrin and chlorauric
acidwere mixed and heated for 2 h in an alkaline solution at 60 C.
Theinvestigation demonstrated that -cyclodextrin could reduce
chlo-rauric acid to gold nanoparticles in strong alkaline condition
[14].To further improve electrochemical performance, some
functionalreagents were also introduced into graphenemetal
nanocompos-ites. The chemical functionalization of graphene offers
the means ofmodifying its already existing fascinating electronic
properties. Itcan also result in the formation of covalent and
ionic bonds as wellas non-covalent van der Waals interactions,
which would improvethe immobilizations of metal particles on the
graphene nanosheetsas well as the composites on electrode surface.
For example, Sidorovand co-workers developed a method that deposits
graphene elec-trostatically from highly-oriented pyrolytic graphite
onto Si/SiO2surfaces functionalized with
(aminopropyl)trimethoxysilane [15].The method for decorating
graphene with noble metal nano-structures may have interesting
optical, electronic, and chemicalproperties for the applications in
nanoelectronics, sensing, and
see front matter 2012 Published by Elsevier
Ltd.rg/10.1016/j.electacta.2012.08.094and controllable strategy to
fabricate wmposite lm as sensing materials for thnol with
electrodepositiona,, Sun Xiulanb, Xia Qianfanga, Li Ruiyi c, Fang
Yinmical and Material Engineering, Jiangnan University, Wuxi
214122, Chinad Science and Technology, Jiangnan University, Wuxi
214122, Chinaersity of Ireland, Maynooth, Co., Kildare, Irelandu
Technology Co., Ltd., Hangzhou 310009, China
e i n f o a b s t r a c t/ locate /e lec tac ta
dispersed graphenegolddetection of hydroquinone and
d, Yang Shupinga, Liu Junkanga
-
L. Zaijun et al. / Electrochimica Acta 85 (2012) 42 48 43
Fig. 1. Photoe n for 1nanocomposit
catalysis. Mfor fabricatgold nanopslide. Becauhybrid lm the lm
serysis [16]. Hotime or labo
In recenfor synthesiple, fast, anto GO aqeopotential toimportant
ito fabricateHere, GO wwas then imone-step elthat graphethey are
moresolve the prepare gragraphene laresult, the cites were relm
[2426eration andthe redox reobtained grvery poor d
In the scontrollablenanocompoquinone anallows singwere alternbon
electrodoffers excel
2. Experim
2.1. Chemic
Graphitenol (RC) w(Mainland, phate buffe
ol l1
yed wre p, andation
para
trocchemmica
micrde soltag/Agm wcarbBefor5 mubly. Thscann0.1 Vgednde
cryssed fer anarea sed id wa
10 ms of the solution after 0.5 mg ml1 GO mixed with 0.5 m mol
l1 chlorauric acid solutioes (c).
oreover, Kim and co-workers reported another methoding the
hybrid lm of gold and GO by directly growingarticles on supported
thin layers of GO lms on a glassse of the high desorption efciency
of analytes from thewithout inducing signicant fragmentation of
analytes,ves as successful LDI platform for small-molecule
anal-wever, above methods required multiple steps that arer
consuming.t years, electrochemical reduction of GO is attractives
of the graphenemetal nanocomposite due to its sim-d green nature.
Often, metal nanoparticles were addedus solution. The mixture is
then reduced at a negative
yield a graphenemetal nanocomposites [17]. Mores the
electrochemical method can be directly applied
graphenemetal nanoparticle on the electrode surface.as coated on
the electrode surface, and the electrodemersed in a metallic
precursor solution to perform
ectrochemical reduction [1821]. The study showedne sheets are
not separated by metal particles sincestly located on the surface
of graphene lm [22,23]. Toproblem, Luo and co-workers reported a
new strategy tophenegold composite lm by cyclic voltammetry.
Theyers were spaced by layer of gold nanoparticles. As aonductivity
and surface area of graphenegold compos-markably enchanced compared
to the pure graphene]. However, the method cannot avoid obvious
agglom-
precipitation of GO nanosheets in the electrolyte due toaction
between chlorauric acid and GO. This results theaphenegold
nanocomposite lm is very coarse withispersion (Fig. 1).tudy, we
focus on the development of green and
strategy to fabricate well-dispersed graphenegold
0.01 memploand weChina)puric
2.2. Ap
Elecelectrotrochecrystalelectrocyclic vwith Aplatinuglassy
trode. and 0.0acid/do20 mincyclic from unchandried uquartzwere
udiametin the immerdistilleHCl forsite lm as sensing materials for
the detection of hydro-d resorcinol in real water samples. The
techniquele-layer graphene nanosheet and gold nanoparticlesately
electrodeposited on surface of the glassy car-e. The as-prepared
graphenegold nanocomposite lmlent electrocatalytic activity.
ental
als
, chlorauric acid, hydroquinone (HQ) and resorci-ere obtained
from SigmaAldrich Chemical CompanyChina) and used without further
purication. A phos-red saline (PBS, pH 7.0,
Na2HPO4KH2PO4NaClKCl,
The upper ascrews andside of the experimentimental solua
nitrogen ameasureme
2.3. Electro
GraphiteHummers mwas exfoliaform homoreduced an min (a) and 24 h
(b) and the electrode surface modied graphene/gold
) was prepared in the laboratory. All other reagentsere of
analytical reagent grade or with highest quality
urchased from Shanghai Chemical Company (Shanghai, ultra pure
water (18.2 M cm) puried from a Milli-Q
system was used throughout the experiment.
tus
hemical experiments were performed with an IM6eical system
(ZAHNER Elektrik, German), CHI660B elec-
l workstation (Shanghai, China) and CHI400B quartzobalance (QCM)
(Shanghai, China). Conventional three-ystem was used for
chronopotentiometric deposition,mmetry (CV) and differential pulse
voltammetry (DPV)Cl (saturated KCl) electrode as the reference
electrode,ire as the counter electrode, and bare or modied
on electrode (GCE, 2 mm in diameter) as working elec-e use, the
GCE was polished successively with 1.0, 0.3,
alumina powder, and sonicated in a 6.0 mol l1 nitric distilled
water and ethanol/doubly distilled water foren, the GCE as working
electrode was subjected toing in 0.5 mol l1 H2SO4 solution in a
potential range
to 1.0 V. When the cyclic voltammogram was almost, the electrode
was taken out, cleaned with water andr a stream of nitrogen. The
circular AT-cut 7.995 MHztals coated with polished gold electrodes
on both sidesor QCM analysis. The quartz crystals were 14 mm in
thed 0.2 mm thick and the gold electrodes were 0.196 cm2
and 100 nm thickness. For cleaning purpose, they weren 1 mol l1
NaOH for 20 min. After being washed withter and nitrogen-dried,
they were immersed in 1 mol l1
in and rinsed with distilled water, followed by ethanol.
nd lower pieces of the cell were held together by two
sealed between two O-rings. The QCM crystal had oneelectrode
exposed to the solution. All electrochemical
was carried out under room temperature, and all exper-tion was
degassed by nitrogen for at least 15 min. Then,tmosphere was
maintained during the electrochemicalnts.
deposition of graphene
oxide was prepared from natural graphite by modiedethod [27,28].
The synthesized graphite oxide powder
ted in ultra pure water by ultrasonication for 30 min togeneous
GO dispersion. Then, GO was electrochemicallyd deposited on the
surface of glassy carbon electrode
-
44 L. Zaijun et al. / Electrochimica Acta 85 (2012) 42 48
Fig. 2. Typical c) andSection 2.3.
with constapersion undelectrode wdry at room
2.4. Electro
Gold nanprepared grin 0.01 mmH2SO4 undtrode was tunder room
2.5. Materi
Infraredimage, Ramobtained useter attenuS4800
eldmicroprobe2200vpc (Rand 20 mA a
3. Results
3.1. Synthe
The userauric acid SEM images of the GCE surface after
electrodeposited in 0.005 (a), 0.01 (b), 0.05 (nt potential at 1.2
V for 50 s in a 0.01 mg ml1 GO dis-er temperature of 10 C. After
the electrodeposition, theas thoroughly rinsed with ultra water and
allowed to
temperature for further modication.
deposition of gold nanoparticles
oparticles were electrochemically deposited on the as-aphene/GCE
with constant potential at 0.25 V for 50 sol l1 of chlorauric acid
solution containing 0.5 mol l1
er temperature of 10 C. After the deposition, the elec-horoughly
rinsed with ultra water and allowed to dry
temperature for further modication.
als characterizations
spectrum (IR), scanning electron microscope (SEM)an spectrum and
X-ray diffraction (XRD) patterns wereing a AVATAR 360 Fourier
transform infrared spectrom-ated total reection infrared
spectroscopy, HITACHI
emission scanning electron microscope, HR800 Raman with a 514 nm
laser excitation and X-ray D/max-igaku Corporation, Japan)
instrument operated at 40 kVnd using Cu K radiation (k = 0.15406
nm), respectively.
and discussion
sis
of an appropriate concentration of GO and chlo- was strongly
required to fabricate well-dispersed
graphenegcontains lapart of GO dissociationmoved to tthe
electroequilibriumtrolyte willand reducetively low obtain smasingle
stepprecipitate ronment duin GO sheetrolyte wasadding anygated the
eduring the concentratithe electroemployed fcovered
wiconcentratiincrease rapthe electrodsheets. Howgraphene snicantly
dThus, a 0.01electrodepo 0.1 (d) mg ml1 of GO dispersion. Other
conditions are described inold nanocomposite lm. Since GO is weak
acid whichrge numbers of carboxyl and hydroxyl groups, onlywill be
dissociated into GO anion due to existing the
equilibrium of weak acid, which GO anions may behe electrode
surface, reduced and nally deposited onde surface under electrical
stress. Based on acidbase
theory, the concentration of the GO anion in the elec- rapidly
increase with increasing pH of the solution
with decreasing pH value. On the one hand, a rela-and constant
GO anion concentration is benecial toll amounts of graphene on the
electrode surface for
electrodeposition. On the other hand, GO is easy tofrom aqueous
phase in relatively strong acidic envi-e to the protonation of
carboxyl and hydroxyl groupsts. Thus, a pH 7.0 of the GO dispersion
as the elec-
employed for the graphene electrodeposition without base and
supporting electrolyte. Further, we investi-ffect of precursor GO
concentration in the electrolytegraphene electrodeposition. As
shown in Fig. 2, the GOon obviously inuence on amounts of the
graphene onde surface. When a very low concentration of GO wasor
the deposition, the electrode surface cannot be wellth the graphene
nanosheets. With increase of the GOon number and density of the
graphene sheets willidly. When GO concentration is about to 0.01 mg
ml1,e surface is almost covered with single-layer grapheneever,
with increasing GO obvious agglomeration of theheets was clearly
observed, which would lead to sig-ecreased surface area of the
modied graphene layer.
mg ml1 of GO dispersion was selected for the graphenesition.
After one-step graphene electrodeposition was
-
L. Zaijun et al. / Electrochimica Acta 85 (2012) 42 48 45
Fig. 3. Typical SEM images of the graphene/GCE surface after
electrodeposited in 0.005 (a), 0.01 (b), 0.were described in
Section 2.4.
completed, chlorauric acid was electrochemically reduced and
thendeposited on the electrode modied graphene with constant
poten-tial at 0.25 V for 50 s in different concentration of
chlorauricacid solution containing 0.5 mol l1 H2SO4. Fig. 3
presents typicalSEM images of the electrode surface modied in
different con-centration of chlorauric acid solution. We clearly
see from Fig. 3chlorauric acid concentration in the electrolyte
remarkably effectson the size and densities of gold nanoparticles.
When a low chlo-rauric acid concentration was employed for the gold
deposition,the gold nanoparticles are very rare with a small size
on the elec-trode surface. With the increasing chlorauric acid
concentrationthe size and densities of gold nanoparticles increased
obviously,which leads to signicantly decrease of the surface area
of thegold-layer. age particlesurface whto 0.01 mmthe each
elemployed foa well-dispeby alternatnanoparticlrepeatabilitmeasured
bFig. 4 exhibduces almothat the eleity.
0
50
100
150
200
0
F (
Hz)
Fig. 4. Decreagraphene or gditions were d
3.2. Structu
Fig. 5 prgraphenegregular andwith an avtern there a38.28, 44.4Au
(1 1 1), centered cuThe (0 0 1) peak of grapgraphene m
educocesstal
vely g sone n
6 pro pring D
the an of ed nphites.A
in t redemovstabs sm
an iphitere ively0 cm
Thedefoespe
C Oeak,However, the single-layer gold particles with an aver-
size of 10 nm were well dispersed on the electrodeen precursor
chlorauric acid concentration is aboutol l1. To obtain single-layer
gold nanoparticles forectrodeposition, a 0.01 mmol l1 chlorauric
acid wasr the gold electrodeposition. Under optimal conditions,rsed
graphenegold nanocomposite lm was preparedely electrodepositing
single-layer graphene and goldes on the electrode surface for 20
cycles. To evaluatey of the strategy, the amounts of modied layer
werey QCM after the each step electrodeposition completed.its the
each step deposition of graphene or gold pro-st same decrease value
of QCM frequency, indicatingctrochemical technique has an excellent
repeatabil-
(graphene)
(gold)
been rtion prlow cryeffectishowingraphe
Fig.are twincludresentphonoincreasent graincreasto 1.31ing
thewere rbe re-ework ilead toent gralm wa relatat 162water.to the C
O, ring andvery w4 8 12 16 20
Cycle number
se value of QCM frequency resulted by single step deposition
ofold. GO: 0.01 mg ml1, chlorauric acid: 0.01 mmol l1, and other
con-escribed in Sections 2.22.4.
groups. Aftecontaining of the mostand IR havgrapheneg
3.3. Electro
To undenanocompo05 (c) and 0.1 (d) mmol l1 chlorauric acid
solution. Other conditions
re characterization
esents typical SEM and XRD images of the as-preparedold
nanocomposite lm. The gold particles are very
these are separated on the wrinkled graphene sheetserage
particle size of about 10 nm. On the XRD pat-re four sharp
diffraction peaks at scattering angles of8, 64.6 and 77.64,
corresponding to crystal planesAu (2 0 0), Au (2 2 0) and Au (3 1
1) of the gold face-bic crystallographic structure (JCPDS card No.
65-2870).peak of graphene oxide almost disappear and (0 0 2)hene
nanosheets is wider and weaker than that of pureaterials. The
results suggest that graphene oxide has
ed into graphene nanosheets during the electrodeposi-s. The
obtained graphenegold nanocomposite shows alinity, and the
restacking of the graphene nanosheets isprevented, corresponding to
the SEM image in Fig. 5a,me gold nanoparticles located on the
surfaces of theanosheets.esents typical Raman and IR spectrum of
the lm. Thereominent peaks on the Raman spectrum of graphene,
band (1355 cm1) and G band (1600 cm1), which rep-mount of sp3
carbons in the surroundings and the E2gsp2 C atoms. Because a
higher level of disorder and anumber of defects in the graphene.
Compared with par-e, the ratio of intensities of the D and G bands
(ID/IG)fter electrochemical reduction, the ID/IG ratio increaseshe
as-prepared graphene-gold nanoparticle lm. Dur-uction process, most
of the oxygen-containing groupsed, and the conjugated G network
(sp2 carbon) wouldlished. However, the size of the re-established G
net-aller than the original one, which would consequentlyncrease in
the ID/IG ratio [29]. IR spectrum of the par-e GO and as-prepared
graphenegold nanocompositeshown in Fig. 6b. We clearly observed
from Fig. 6b
broad peak at 3414 cm1 and relatively sharp peak1 demonstrated
that the samples contain adsorbed
peaks at 1397 cm1 and 1081 cm1 can be assignedrmation vibration
of O H and stretching vibration ofctively. Characteristic bands of
C O carbonyl stretch-
C vibration located at 1720 cm1 and 1250 cm1 are indicating the
small amount of these two functional
r the electrochemical reduction, the removal of oxygen-groups is
clearly indicated by the gradual disappearance
absorption bands. Above results of SEM, XRD, Ramane demonstrated
that we have obtained successfully aold nanocomposite lm with
electrodeposition.
catalytic activity
rstand electrocatalytic activity of the graphenegoldsite lm, we
investigated the effect of varying the scan
-
46 L. Zaijun et al. / Electrochimica Acta 85 (2012) 42 48
Fig. 5. SEM image (a) and XRD patterns (b) of the as-prepared
graphenegold nanocomposite lm.
A B
ty (
a.u
.)
D
G
itta
nce /%
GO
rate on thecontaining 1that all scanpeaks withtials with rpeak
currenroot as shotion corres
Fig. 7. (A) Cyc(from a to ax) 8.0, 8.2, 8.4, 8.Inte
nsi
Tra
nsm0 500 1000 1500 2000 2500
Raman shift/cm-1
360
Fig. 6. Raman (a) and IR spectra (b) of the as-prepared
graphen
performance of the modied electrode in pH 7.0 PBS m mol l1
K4Fe(CN)6 in 0.1 mol l1 of KCl. Fig. 7A shows
rates resulted in well-dened reduction and oxidation little
shift in both cathodic and anodic peak poten-espect to scan rate.
Further, both cathodic and anodicts are linearly proportional with
the scan rate squarewn in Fig. 7B, which indicates that electrode
reac-ponds to the solution phase quasi-reversible process.
The small pelectron traapparent e37.67 0.19
ks = mnFvRT
-120
-90
-60
-30
0
30
60
90
120
-0. 200.20.40.6
I/A
E vs(Ag/AgCl/V)
a
ax
-120
-80
-40
0
40
80
120A B
0.4
I p/
A
lic voltammograms of the graphenegold nanocomposite modied GCE
in pH 7.0 PBS coof 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2.0,
2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 6, 8.8,
9.0, 9.2, 9.4, 9.6, 9.8 and 10 V/s. (B) Plot of the Ip vs.
v1/2.Grapite
The film60012001800240030000
Wavenumber/cm-1
egold nanocomposite lm.
eak-to-peak separation value (Ep) illustrates a fastnsfer rate.
When the nEp is less than 200 mV, thelectron transfer rate constant
(ks) is estimated to be
cm s1 by using the following equation [30]:
(1)
1 1.6 2.2 2.8
Scan ra te1/2/V1/2 s-1/2
ntaining 1 mmol l1 K4Fe(CN)6 in 0.1 mol l1 KCl at various scan
rates4.6, 4.8, 5.0, 5.2, 5.4, 5.6, 5.8, 6.0, 6.2, 6.4, 6.6, 6.8,
7.0, 7.2, 7.4, 7.6, 7.8,
-
L. Zaijun et al. / Electrochimica Acta 85 (2012) 42 48 47
100
200A B
G/GCE
G-Au/GCE
-125
-95
-0. 4-0.3-0. 2-0.10
E vs (Ag/AgCl)/V
(RC)(HQ)
GCE
G/GCE
G-Au/GCE
Fig. 8. CVs (a) BS containing 1 104 mol l1 of HQ and 1 104 mol
l1 of RC. The DPVparameters we v initial potential.
where m is temperaturThe value ofand bare GC
To furthegraphenegrials to syntypical CVsGCE (G/GCGCE (GAuHQ and
1 very weak G/GCE and ously with for their siGAu/GCE RC than
G/Gtiles imprographene n
3.4. Analyti
Fig. 9 diand RC. Wicurrent (Ip1.2 104 mThe linear signicant RC,
with stwhich Ip issitivities of117.83 A be 5.2 10were obtain(S/N =
3). ElHQ and RC adeviation (Rreproducibiconditions aof the
sensolong term ssamples. Thviously rep[31,32].
terference of coexisting substances
evaluate selectivity of the sensor, the inuence of variousnces
on the determination of 1.0 106 mol l1 of HQ and RCdied by DPV. It
was found that 1500-fold Ca(II), Mg(II), Na(I),
H4(I), Cu(II), Zn(II), Al(III), F, Cl, Br, NO3, SO42,
CO32,0-fold glucose, ascorbic acid, uric acid do not interfere
withermination. The tolerance limit was estimated to be less thanhe
relative error. This indicates the proposed method has annt an
plicanol in
feasvestis weater, he cament-200
-100
0
-0.4 -0.2 0 0.2 0.4 0.6
I/A
E vs (Ag/AgCl)/V
GCE -65
-35
-5
I p/
A
at scan rate of 100 mV/s and DPVs (b) of GCE, G/GCE and GAu/GCE
in pH 7.0 Pre set to a scan rate of 4 mV/s, 50 mV pulse amplitude,
20 ms pulse width and 0.4
a parameter related to peak-to-peak separation; T is thee; n is
the number of electrons; and v is the scan rate.
ks is higher than graphene modied GCE (11.02 cm s1)E (4.47 0.13
cm s1).r evaluate the electrocatalytic activity, the as-preparedold
nanocomposite lm was applied as sensing mate-chronously detection
of HQ and RC. Fig. 8 presents
(a) and DPVs (b) of bare GCE, graphene modiedE) and graphenegold
nanocomposite lm modied/GCE) in pH 7.0 PBS containing 1 104 mol l1
of
104 mol l1 of RC. As expected, bare GCE showscurrent response to
HQ and RC. In comparison, bothGAu/GCE can well distinguish HQ and
RC, simultane-increased oxidation currents, showing great
potentialmultaneous determinations. Moreover, we observedexhibits
more sensitive current response to HQ andCE. This is because the
introduction of gold nanopar-
ves the conductivity and avoids the agglomeration
ofanosheets.
cal characteristics of the sensor
splays DPV curves for different concentration of HQth the
increasing HQ and RC concentration the peak) increased linearly in
the ranges of 1.6 108 tool l1 for HQ and 1.0 108 to 2 106 mol l1
for RC.
equations were Ip = 0.9547 C for HQ, with
statisticallycorrelation coefcient of 0.9996, and I = 3.6997 C
for
3.5. In
To substawas stuK(I), Nand 20the det5% of texcelle
3.6. Apresorci
Thewas insampleTap wfrom texperip
atistically signicant correlation coefcient of 0.9998, in A and
concentration (C) in mol l1. The sen-
DPV response are 30.5 A M1 cm2 for HQ andM1 cm2 for RC. The
detection limits were found to
9 mol l1 for HQ and 2.2 109 mol l1 for RC thated from the
signal-to-noise characteristics of these dataeven successive
determinations of 1 106 mol l1 oft one modied electrode resulted in
a relative standardSD) of 1.22% for HQ and 1.81% for RC, suggesting
a highlity. The proposed sensor was stored in air at ambientnd its
sensitivity was checked every day. The responser was 95% of its
initial value after 180 days which showstability and very good
sensitivity for the analysis of realese analytical parameters are
better than results pre-orted for electrochemical determination of
HQ and RC
Fig. 9. (a) DPVwere set to a 0.4 v initial ppeak current
(ti-interference ability.
tion to the determination of hydroquinone and water samples
ibility of the developed method for possible applicationsgated
by analyzing real water samples. Waste waterre collected from the
factory for producing HQ and RC.ground water and lake water samples
were collectedmpus at Jiangnan University. The spike and recoverys
were performed by measuring the DPV responses to curves of
different concentration HQ and RC. The DPV parametersscan rate of 4
mV/s, 50 mV pulse amplitude, 20 ms pulse width andotential. Insets:
calibration plots of concentration of HQ and RC vs.Ip).
-
48 L. Zaijun et al. / Electrochimica Acta 85 (2012) 42 48
Table 1The results for the determination of HQ and RC in real
water samples (N = 5).
Sample Tap water Lake water Ground water Waste water
HQ RC HQ RC HQ RC HQ RC
Added (mol l1) 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00Determined
(mol l1) 0.99 0.98 1.01 1.02 0.96 0.99 1.16 1.09RSD (%) 1.7 1.1 2.3
1.5 1.0 1.9 1.8 1.4Recovery (%) 99.0 98.0 98.8 101.2 96.0 99.7
101.2 103.4
the sample in which the known concentrations of HQ and RC
wereadded. The mean of each sample and recovery of each spiked
sam-ple were calculated and the values are reported in Table 1.
Table 1shows the recovery of HQ and RC for spiked samples analysis
is inthe range of 96.0103.4%, indicating good accuracy and
precision.
4. Conclusions
Green and controllable strategy was developed for the
fabri-cation of well-dispersed graphenegold nanocomposite lm.
Theinvestigation demonstrated that the amounts of graphene andgold
nanoparticles for each layer can be well pre-determined
bycontrolling concentrations of GO and metallic precursor. Due
togood dispersivity, the as-prepared lm shows better
electrocat-alytic activity towards hydroquinone and resorcinol than
that ofother technologies in literatures. The method for the
preparationof grapheneable, it can composite tion such as
Acknowled
The autNational N20771045 ajiang Provinsupport scisponsored
b
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Green and controllable strategy to fabricate well-dispersed
graphenegold nanocomposite film as sensing materials for the ...1
Introduction2 Experimental2.1 Chemicals2.2 Apparatus2.3
Electrodeposition of graphene2.4 Electrodeposition of gold
nanoparticles2.5 Materials characterizations
3 Results and discussion3.1 Synthesis3.2 Structure
characterization3.3 Electrocatalytic activity3.4 Analytical
characteristics of the sensor3.5 Interference of coexisting
substances3.6 Application to the determination of hydroquinone and
resorcinol in water samples
4 ConclusionsAcknowledgementsReferences