Electrodeposition of ZnCo2O4 nanoparticles for biosensing applications

Article abstract of DOI:10.1039/c5ra11011d

We report the growth of ZnCo₂O₄ nanoparticles on indium tin oxide (ITO) coated glass substrates by a simple and highly reproducible electrodeposition method. The as-deposited ZnCo₂O₄ nanoparticles are characterized by various structural and microscopical tools for assessing their crystalline and morphological features. Electrochemical sensing properties of the as-prepared ZnCo₂O₄ nanoparticles towards glucose and dopamine are studied. ZnCo₂O₄ nanoparticles show linear response with respect to change in glucose concentration varying from 10 to 290 μM and possess an LOD value of 36.9 μM and a sensitivity of 0.92 μA μM^-1 cm^-2. In a similar way, ZnCo₂O₄ exhibits a linear response with respect to change in dopamine concentration varying from 5-100 μM with an LOD value of 15.4 μM and a sensitivity of 0.55 μA μM^-1 cm^-2 respectively.

Full text of DOI:10.1039/c5ra11011d

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Electrodeposition of ZnCo
2
O
4
nanoparticles for biosensing appli
D
c
O
a
I:
t
1
i
0
o
.1039/C5RA11011D
n
s
Kusha Kumar Naik, and Chandra Sekhar Rout,*a
a
a
School of Basic Sciences, Indian Institute of Technology, Bhubaneswar751013, India
ABSTRACT:
We report the growth of ZnCo
2
4
O nanoparticles on indium tin oxide (ITO) coated glass
substrates by a simple and highly reproducible electrodeposition method. The as-deposited
ZnCo nanoparticles are characterized by various structural and microscopical tools for
assessing its crystalline and morphological features. Electrochemical sensing properties of the
as-prepared ZnCo nanoparticles towards glucose and dopamine are studied. ZnCo
2
O
4
2
O
4
2
O
4
nanoparticles show linear response with respect to change in glucose concentration varying
from 10 to 290 µM and possess the LOD value of 36.9 µM and the sensitivity of 0.92 µAμM-
1
-2
cm . In a similar way, ZnCo
2
O
4
exhibit linear response with respect to change in dopamine
concentration varying from 5-100 µM with the LOD value of 15.4 μM and the sensitivity of
-
1
-2
0
.55 µAμM cm respectively.
Keywords: Spinel, Nanoparticles, Electrodeposition, Biosensor
Corresponding author mail: csrout@iitbbs.ac.in (Dr. C.S. Rout)
1

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1
. Introduction
DOI: 10.1039/C5RA11011D
ZnCo
2
4
O is a regular ternary spinel oxide and is known to exhibit a large degree of cation
disorder over the two types of lattice sites, those tetrahedrally or octahedrally by the oxygen.1,2
It is a promising p-type functional material that has been raised considerable interest for
potential applications in Li-ion batteries, electrocatalysts and supercapacitors due to their
interesting electrochemical and catalytic properties.2–6 In ZnCo
the tetrahedral sites while Co cations are evenly distributed to all the octahedral sites, and the
2
4
O crystal, Zn cations occupy
-2
+2
+3
anions (O ) tend to coordinate both the cations Zn and Co , tetrahedrally and octahedrally
respectively to form a close packed FCC structure.2,7,8
Fabrication of arrays of nanoparticles have enormous relevance in the fields where important
electrochemical processes are involved and the morphology of electrodes strongly affect their
performance.9,10 Assemble nanoarrays possess enhanced reactivity and stability by providing
pathways for electrolyte ions and electrons, thereby realizing maximum utilization of
electrochemical properties of the material.11,12 Electrodeposition is the suitable method for
nanostructure due to its enhanced driving force. The driving force drives the dissolved ions and
atoms towards the substrate and assembles on it creating a suitable morphology and
composition of nanostructure which perform novel material properties.13,14 Electrodeposition
takes advantage of charged particles in the solution and is an inexpensive low temperature
method to produce uniform films.
Biosensors are becoming essential in the field of health care, chemical and biological analysis
,
environmental monitoring, and food processing industries.15,16Amongs the biosensors, glucose
sensor and dopamine sensors are more important. The amperometric biosensors based on non-
enzymatic glucose and dopamine are still challenges to perform better sensitivity, low detection
2

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limit and excellent range of detections. To achieve this goal, one promising way is to employ
DOI: 10.1039/C5RA11011D
nanostructure materials, and efforts have been made during the past few decades. 17,18
In the present study, we prepared thin film of ZnCo nanoparticles on ITO coated glass
2
O
4
substrates by electrodeposition method. The electrodeposited film exhibited high
electrocatalytic activity towards the detection of glucose (GL) and dopamine (DE) molecules.
2
. Experimental section
.1 Synthesis of ZnCo O nanoparticles
2
2
4
In a typical procedure, the ITO coated glass substrate was thoroughly cleaned with
ethanol, acetone and de-ionized water prior to the electrodeposition process. 3 mmol Zn
NO 6H O and 6 mmol Co (NO 6H O were dissolved in 10 ml of de-ionized (DI) water
and taken in a glass cell. 60 mmol of urea (CH O) was slowly added into the solution
(
3
)
2
2
3
)
2
2
4
N
2
followed by further addition of 3 mmol potassium chloride (KCl) acting as a supporting
electrolyte. The counter electrode (Pt wire), reference electrode (Ag/AgCl) and working
electrode (ITO/glass) were dipped into the solution and temperature of the glass cell containing
the solution was maintained at 70º C during the electrodeposition process. Electrodeposition
was carried out with the help of a Potentiostat/ Galvanostat (Technoscience Ltd., Bangalore,
India) by applying a potential of -1.3 V for 180 s with constant stirring of the solution. At high
potential and due to the heating of the solution, urea hydrolyzes and helps to nucleate the Zn+2
+
2
and Co ions to form the ZnCo
2
O
4
nanoparticle. The ZnCo
2
4
O nanoparticles uniformly
deposited on the surface of conducting substrate and the as-synthesized film was dried naturally
then annealed at 500º C for 6 h to achieve better crystallinity.
3

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2
.2 Materials characterization
DOI: 10.1039/C5RA11011D
The Crystal structure of the as-synthesized ZnCo
2
4
O nanoparticles film was characterized by
X-ray diffractometer (Bruker D8 Advanced diffractometer using Cu-Kα radiation (λ = 1.54184
Å)). Morphology and composition of the as-prepared samples were examined by FESEM
(
(MERLIN Compact with GEMINI I electron column, Zeiss Pvt. Ltd., Germany) equipped
with energy dispersive X-ray spectroscopy (EDAX).
2
.3 Electrochemical measurement
The electrochemical measurement of the deposited ZnCo
2
4
O nanoparticles film was carried out
in a same glass cell with three electrodes configuration system. The 0.1 M of NaOH aqueous
solution was used as the electrolyte solution to perform the biosensing applications of 0.5 M
of glucose and dopamine molecules. The cyclic voltammetric (CV) and chrono-amperometric
(
CA) experiments were performed in NaOH solution in order to investigate the electrochemical
activity of the as-prepared ZnCo nanoparticles. For CV experiments, 6 ml of NaOH solution
2
O
4
was taken in a same glass cell with three electrodes system and a linear voltage 0 to 0.75 V for
glucose study and 0 to 0.7 V for dopamine study were supplied to the electrodes to observe the
catalytic behaviour of the ZnCo
concentrations and dopamine concentrations were added separately to obtain the sensing
activities of the ZnCo nanoparticles. Similarly, the IT and interference experiment were
2
4
O nanoparticles. Then finally, 100 μM of glucose
O
2 4
carried out in a glass cell of three electrodes set up containing 140 ml of NaOH solution. Then
the solution was stirred at 1100 rpm and a potential value of 0.4 V was applied to three
electrodes .Again for IT measurement, various concentrations (5,10,15,20,30,40,50 μM) of
glucose and dopamine molecules were dropped into the solution separately in a interval of 70
s to study the electrochemical response of the synthesized material.
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To perform the selectivity of the synthesized material various interfering species like uric acid
DOI: 10.1039/C5RA11011D
(
UA), lactic acid (LA) and ascorbic acid (AA) were selected then 0.05 M of each interfering
species was dissolved in 10 ml of NaOH solution separately in a glass beaker then 10 μM of
each species added into the solution periodically in a interval of 70 s.
3. Results and discussion
3
.1. Characterization of ZnCo
2
O nanoparticles
4
FESEM images of the ZnCo
2
4
O nanoparticles are depicted in Fig.1a, and 1b, which
show that the as-synthesized thin film consists of spherical structures having 5-10 nm diameters
and the nanoparticles are sparsely populated throughout the ITO surface. The nanoparticles are
uniformly distributed with precise control over the distribution. The XRD pattern of the
ZnCo
2
4
O nanoparticles is shown in Fig. 1c and confirms the formation of pure and crystalline
phase. The peaks at 2θ = (31.28), (36.85), (44.82), (55.67), (59.37), (65.25) and (68.65)
corresponding to the (220), (311), (400), (422), (511), (440) and (531) planes of the standard
JCPDS value of spinel ZnCo
2
4
O (JCPDS-812295). The peak positioned at 28.70 Å is
acquainted to the hydroxide hydrate of Zinc-cobalt oxide (JCPDS-211477). To know the effect
of annealing we performed XRD of the as-prepared sample and the data is shown in Fig. S1.
No characteristic peak of other compounds was observed indicating that the as-prepared film
shows good impurity. EDAX and elemental mapping confirmed the presence of Zn, Co and O
confirming the formation of pure ZnCo
2
O
4
phase, Fig. 1d and Fig. 2. Raman spectra of the
ZnCo shows characteristic peaks of spinel Zinc cobalt oxide (Fig. S2, Supplementary
2
O
4
-1
Information). The peak at 477 and 515 cm are assigned to the strong vibrational modes ꢀ
ꢁ
ꢄꢃꢅ
and ꢂꢃꢁ respectively. The Raman vibrational mode (i.e. ꢆ ) results in peak positioned at 686
ꢇꢁ
-
1
cm .
5

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DOI: 10.1039/C5RA11011D
3
.2 Electrochemical sensing towards glucose
.2.1 Cyclic voltammetric studies
3
The CVs experiment has been performed in the three electrodes system in a glass cell with the
-1
applied potential of 0 to 0.75 V at scan rate 40 mvs . During anodic scan, small hump at 0.31
V and broad peak between 0.4 to 0.65 V observed and again peak at 0.45 V and small hump at
0.31 V observed during cathodic scan, Fig. 3a. The redox peak indicated the synthesized
material is ZnCo
2
O
4
nanoparticles.19–22
The mechanism and electrochemical catalysis of the ZnCo
2
4
O nanoparticles towards
glucose molecules can be understood from schematic diagram Fig. 4a and as follows:
+
2
+2
During anodic scan: When the voltage applied to the electrodes, the Zn and Co ion
+
3
+3
species present on the surface of substrate oxidise to form Zn and Co ions. Therefore, the
oxidation hump at 0.31 V and broad range of oxidation peak 0.4 to 0.65 V observed due to
+2
+3
+2
3+
23-25
oxidation of Zn /Zn and Co /Co cations.
ZnCo
2
O
4
+ OH¯ + H
2
O ↔ Zn (OH) + 2CoOOH+ e¯---------------------------------------------(1)
2
Zn (II) + Co (II) ↔Zn (III) + Co (III) + 2e¯---------------------------------------------------------(2)
Similarly, when glucose molecules (100 μM) was dropped into the solution, the glucose
molecules also oxidised in the applied potential range and transferred to gluconolactone
molecules.22,23
+
Glucose (C H
6 12
O
6
) → Gluconolactone (C
6
H
10
O
6
) + 2H + 2e¯-----------------------------------(3)
The oxidations of metal ions and glucose molecules occur simultaneously at the same applied
potential range inside the solution. The electrochemical activity between glucose to
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gluconolactone molecule is directly proportional to the oxidation states of Zn and Co species.
DOI: 10.1039/C5RA11011D
2
6
Thus the glucose molecules are responded by the ZnCo
2
4
O nanoparticles and the change in
oxidation peaks are observed in the same potential range.19-22 Then 100 μM of glucose
concentrations added into the solution respectively. The oxidation peaks and peak currents (I )
p
increased successively with the increasing glucose concentration from 100 to 1000 μM in the
solution .24, 26, 29, 30
During cathodic scan: In the cathodic scan, the applied potential is reversed i.e (0.75 V to
0
), therefore, the absorbed electrons are released from ZnCo
reduction peaks are observed.
Zn (III) + Co (III) + 2e¯ ↔ Zn (II ) + Co (II)-------------------------------------------------------(4)
The continuation of the oxidation and reduction of the metal ions present on the ZnCo
2
O electrode into the solution and
4
2
O
4
electrode surface determine the sensing of glucose molecules. The sensing of the glucose
molecules not only depend on the electrocatalytic behaviour of the metal ions but also the
morphology, active edges, crystal structure, dimensions of the nanostructure, composition, pH
and chemical environment of the electrolytes.10,15
Fig. 3c shows the CVs data of ZnCo
2
4
O /ITO in 100 µM of glucose concentration at
different scan rates. By increasing the scan rate, the amplitude of the redox peak current
increases significantly and the oxidation peak position shifted towards positive side and
reduction peak position shifted towards negative side. These observations indicate that the
oxidation process occurring at the electrode surface is a diffusion controlled process. 23,24
3
.2.2 Chrono-amperometric studies
Chrono-amperometric (IT) response of the ZnCo
2
4
O nanoparticles has been carried out
in a potential value of 0.4 V under stirring condition at 1100 rpm. When 10 µM of glucose
molecules were dropped into the solution, the current rose instantly from the horizontal line
and again achieved to horizontal line showing responding time 22 s. Then 10, 20,30,40,50 µM
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of glucose molecules were added continuously into the solution at a time interval of 70 s, Fig.
DOI: 10.1039/C5RA11011D
5
a. The sensitivity of the ZnCo
2
O
4
/ITO can be calculated by taking into consideration of the
calibration graph and it showed linear range of detection 10-290 µM, limit of detection (LOD)
-2
3
6.9 μM with sensitivity 0.92 µAµMcm .
One of the most important analytical factors for an amperometric biosensor is the
selectivity of the sensor towards target analytes. The interference study has been carried out at
.4 V potential under the same experimental condition in the glass cell by adding the 10 μM of
0
UA, DA, LA and AA continuously into the solution in the 70 s time interval which is shown
in Fig. 5c. It is observed that the selectivity of the sensor is good even in the presence of
interfering species. To investigate the reproducibility of the ZnCo
2
4
O electrode, five
independently fabricated electrodes were tested for glucose sensing and it showed an
acceptable reproducibility with a relative standard deviation of 3.1% for the current determined
at a glucose concentration of 10 µM. The stability of the sensor performance was tested by
monitoring the remaining amount of current response after successive cycling of the electrode
for 5000 circles in the same applied potential at 100 mV/s scan rate. The material exhibited
about 80% stability (Fig. S5)
3.3 Electrochemical dopamine sensing
3.3.1 Cyclic voltammetric studies
The CVs experiment for dopamine study has been performed at 0 to 0.7 V at 40 mV/s
scan rate and it is observed that when 100 µM dopamine molecules was added into the solution,
two distinct peaks at 0.31 V and broad peak 0.4 to 0.65 V appeared. The peak at 0.31 V and
broad peak from 0.4 to 0.65 V range corresponds to the redox reaction of ZnCo
2
O
4
nanoparticle.25–29
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The electrochemical reaction and the mechanism behind dopamine sensing can be
DOI: 10.1039/C5RA11011D
n
explained using eq (1), (2) and (4) and its schematic diagram, Fig. 4a.
+
Dopamine (C
8
H11NO
2
) →C
8
H
9
NO
2
+ 2H + 2e¯---------------------------------------------------(5)
The hydrogen atoms attach with the dopamine molecule partially breaks down in the
applied potential range and release two electrons into the solution (eqn-5 and Fig. 4c). These
two electrons released from each dopamine molecules lead towards increasing of oxidation
peak current (I ). The peak current increased successively with addition of dopamine
p
concentrations from 100 μM to 1000 μM which demonstrate the linear response of ZnCo
2
O
4
nanoparticles.21,22,30,31, 40
The CVs of the ZnCo
2
O /ITO at different scan rates in the presence of 100 µM
4
dopamine molecules has been performed and shown in Fig. 6c. Both the oxidation and
reduction peak currents increased linearly with the increase in scan rates which clearly
indicated that the oxidation reaction occurred on the electrode surface is diffusion controlled
process.19,20,32,33
3
.3.2 Chrono-amperometric studies
The CA studies of dopamine molecules have been executed in the same parameters
When 5 µM of dopamine molecule was added into the solution the current value increased
instantly from horizontal line showing its response time 20 s, Fig. 7d.Then the various
concentrations of dopamine molecules added in to the solutions in the interval of 70 s. The
calibration graph is shown in Fig. 7b which indicates that the sensor possesses a linear range
-1
-2
of detection from 5 -100 µM with the sensitivity value of 0.55 µAµM Cm and the LOD value
of 15.4 µM.
The interference effect of the ZnCo
2
4
O /ITO towards dopamine sensing in the presence of
interference species has been carried out and is shown in Fig. 7c. The stability of the
ZnCo
2
O
4
/ITO towards dopamine sensing has been ascertained by performing CV of 500 cycles
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DOI: 10.1039/C5RA11011D
in the presence of 100 µM dopamine molecules (Fig. S5). It is observed that ZnCo
2
O /ITO
4
exhibited good stability by achieving ~82 % of the initial current after 5000 cycles. For real
sample application of the ZnCo /ITO, the CVs and CAs experiment have been carried out
in sodium phosphate buffer solution (PBS) with pH which is shown in Fig. S3.
2
O
4
4
. Conclusions
Thin films of ZnCo
2
O
4
nanostructure have been deposited onto an ITO substrate by a
facile low-temperature and cost effective electrodeposition method. The nanoparticles are pure
in form, uniform and sparsely populated over ITO surface having nanoparticle size 5-10 nm.
The electrochemical sensing properties of ZnCo
2
4
O nanoparticle towards glucose and
dopamine were investigated. Large surface area of the deposited nanoparticles and enhanced
electrochemical properties due to the large number of active sites played vital role for the
detection of low concentration of glucose and dopamine molecules. The ZnCo
2
O
4
nanoparticle
-2
electrode based sensor exhibited high sensitivity of 0.92 µAµMcm with a LOD 36.9 µM for
-1
-2
glucose and sensitivity of 0.55 µAµM cm and the LOD 15.4 µM for dopamine molecules.
Hence, ZnCo nanoparticle prepared by cost effective electrodeposition method paves the
way for the development of glucose and dopamine sensors.
2
O
4
1
0

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DOI: 10.1039/C5RA11011D
References
1
P. F. Ndione, Y. Shi, V. Stevanovic, S. Lany, A. Zakutayev, P. A. Parilla, J. D. Perkins, J. J. Berry,
D. S. Ginley and M. F. Toney, Adv. Funct. Mater., 2014, 24, 610–618.
2
3
T. W. Kim, M. A. Woo, M. Regis and K.‐S. Choi, J. Phys. Chem. Lett., 2014, 5, 2370–2374.
M. A. Woo, M.‐S. Song, T. W. Kim, I. Y. Kim, J.‐Y. Ju, Y. S. Lee, S. J. Kim, J.‐H. Choy and S.‐J.
Hwang, J. Mater. Chem., 2011, 21, 4286–4292.
4
D. Cai, H. Huang, D. Wang, B. Liu, L. Wang, Y. Liu, Q. Li and T. Wang, ACS Appl. Mater.
Interfaces, 2014, 6, 15905–15912.
5
6
Y. Qiu, S. Yang, H. Deng, L. Jin and W. Li, J. Mater. Chem., 2010, 20, 4439–4444.
F. M. Courtel, H. Duncan, Y. Abu‐Lebdeh and I. J. Davidson, J. Mater. Chem., 2011, 21, 10206–
1
0218.
7
8
K. K. and P. Konstantinov, J. Phys. Condens. Matter, 1993, 5, 9287.
S. Ratha, R. T. Khare, M. A. More, R. Thapa, D. J. Late and C. S. Rout, RSC Adv., 2015, 5, 5372–
5
378.
9
1
K. Tian, M. Prestgard and A. Tiwari, Mater. Sci. Eng. C, 2014, 41, 100–118.
0
1
S. K. Arya, S. Saha, J. E. Ramirez‐Vick, V. Gupta, S. Bhansali and S. P. Singh, Anal. Chim. Acta,
2
012, 737, 1–21.
1
C. J. Murphy, T. K. Sau, A. M. Gole, C. J. Orendorff, J. Gao, L. Gou, S. E. Hunyadi and T. Li, J.
Phys. Chem. B, 2005, 109, 13857–13870.
1
1
2
3
M. Zhang, G. Zuo, Z. Zong, H. Cheng, Z. He, C. Yang and G. Zou, Small, 2006, 2, 727–731.
V. Armel, O. Winther‐Jensen, R. Kerr, D. R. MacFarlane and B. Winther‐Jensen, J. Mater.
Chem., 2012, 22, 19767–19773.
1
1
1
1
1
4
5
6
7
8
J. Sun, X. Liu, L. Meng, W. Wei and Y. Zheng, Langmuir, 2014, 30, 11002–11010.
M. Ahmad, C. Pan, Z. Luo and J. Zhu, J. Phys. Chem. C, 2010, 114, 9308–9313.
N. A. Rakow and K. S. Suslick, Nature, 2000, 406, 710–713.
J. Zhao, F. Wang, J. Yu and S. Hu, Talanta, 2006, 70, 449–454.
H. Zhou, H. Chen, S. Luo, J. Chen, W. Wei and Y. Kuang, Biosens. Bioelectron., 2005, 20, 1305–
1
311.
1
1

RSC Advances
Page 12 of 20
View Article Online
DOI: 10.1039/C5RA11011D
1
9
X.‐C. Dong, H. Xu, X.‐W. Wang, Y.‐X. Huang, M. B. Chan‐Park, H. Zhang, L.‐H. Wang, W. Huang
and P. Chen, ACS Nano, 2012, 6, 3206–3213.
2
2
2
0
1
2
C.‐W. Kung, C.‐Y. Lin, Y.‐H. Lai, R. Vittal and K.‐C. Ho, Biosens. Bioelectron., 2011, 27, 125–131.
I. G. Casella and M. Gatta, J. Electroanal. Chem., 2002, 534, 31–38.
Y. Ding, Y. Wang, L. Su, M. Bellagamba, H. Zhang and Y. Lei, Biosens. Bioelectron., 2010, 26,
5
42–548.
2
2
3
4
Y. Zou, L. He, K. Dou, S. Wang, P. Ke and A. Wang, RSC Adv., 2014, 4, 58349–58356.
R. K. Srivastava, S. Srivastava, T. N. Narayanan, B. D. Mahlotra, R. Vajtai, P. M. Ajayan and A.
Srivastava, ACS Nano, 2012, 6, 168–175.
2
2
2
5
6
7
T. Kong, Y. Chen, Y. Ye, K. Zhang, Z. Wang and X. Wang, Sensors Actuators B Chem., 2009, 138,
3
44–350.
Y.‐T. Wang, L. Yu, Z.‐Q. Zhu, J. Zhang, J.‐Z. Zhu and C. Fan, Sensors Actuators B Chem., 2009,
36, 332–337.
1
J. X. Wang, X. W. Sun, A. Wei, Y. Lei, X. P. Cai, C. M. Li and Z. L. Dong, Appl. Phys. Lett., 2006,
8, ‐.
8
2
2
8
9
X. Liu, Z. Chang, L. Luo, T. Xu, X. Lei, J. Liu and X. Sun, Chem. Mater., 2014, 26, 1889–1895.
S. Palmas, F. Ferrara, A. Vacca, M. Mascia and A. M. Polcaro, Electrochim. Acta, 2007, 53,
4
00–406.
3
3
3
3
3
0
1
2
3
4
C. Xia, N. Wang, L. Wang and L. Guo, Sensors Actuators B Chem., 2010, 147, 629–634.
L. Fang, K. Huang, B. Zhang, B. Liu, Y. Liu and Q. Zhang, RSC Adv., 2014, 4, 48986–48993.
C. L. Weaver, H. Li, X. Luo and X. T. Cui, J. Mater. Chem. B, 2014, 2, 5209–5219.
I. de O. Matos and W. A. Alves, ACS Appl. Mater. Interfaces, 2011, 3, 4437–4443.
G. Vijayaprasath, R. Murugan, J. Shankara Narayanan, V. Dharuman, G. Ravi and Y. Hayakawa,
J. Mater. Sci. Mater. Electron., 2015, 26, 4988–4996.
3
5
Z. W. Zhao, X. J. Chen, B. K. Tay, J. S. Chen, Z. J. Han and K. A. Khor, Biosens. Bioelectron.,
2
007, 23, 135–139.
1
2

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DOI: 10.1039/C5RA11011D
Table-1: Comparison of glucose sensor performance of zinc oxide based material with the
present work
Electrodes
Sensitivity
-
Linear
range
Limit of
detection
Response
time
References
(LOD)
3
4
Co doped
ZnO
32 mM
5 µM
4s
nanoparticle
3
5
ZnO: Co
13.3
μA/mAcm
0-4 mM
20 μM
8 s
22 s
2
-
1
-
ZnCo
2
O
4
0.92 µAμM cm 10-290 μM 36.9 μM
Present
work
2
Table -2: Dopamine sensor performance of ZnCo
2
4
O nanoparticles.
Electrodes
Sensitivity
Linear
range
Limit of
detection
Response
time
References
(LOD)
-
1
-
ZnCo
2
O
4
0.51 µAμM cm 10-100 μM 15.4 μM
20 s
Present
work
2
1
3

RSC Advances
Page 14 of 20
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DOI: 10.1039/C5RA11011D
Fig. 1 (a) Low and (b) high magnification SEM images of ZnCo
2
4
O thin film nanoparticles on
ITO coated glass substrate with the inset in (a) showing optical image of an as-prepared thin
film sample. (c) XRD pattern and (d) EDAX pattern with percentage of the elements of the
ZnCo
2
4
O nanoparticles.
1
4

Page 15 of 20
RSC Advances
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DOI: 10.1039/C5RA11011D
Fig. 2 (a) SEM images of the large area thin film of ZnCo
2
4
O nanoparticles, corresponding
elemental mapping of the elements; (b) Zn, (c) Co, and (d) O respectively.
1
5

RSC Advances
Page 16 of 20
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DOI: 10.1039/C5RA11011D
Fig. 3 (a) CVs of ZnCo
2
4
O nanoparticles in 0.1 M NaOH with different concentration of
glucose (concentration of glucose varies from 100 µM to 1000 µM). (b) Obtained anodic peak
current against different concentration of glucose molecules. (c) CVs at different scan rates in
the presence of 100 µM glucose, (d) change in glucose oxidation and reduction peak current
against square root of scan rate.
1
6

Page 17 of 20
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DOI: 10.1039/C5RA11011D
Fig. 4 (a) Schematic representation of the glucose and dopamine sensing mechanism, (b)
structural representation of the glucose and gluconolactone molecule, (c) structural
representation of dopamine and its oxidation state of dopamine molecules.
1
7

RSC Advances
Page 18 of 20
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DOI: 10.1039/C5RA11011D
Fig. 5 (a) CA response of ZnCo
in 0.1 M NaOH solution at 0.4 V, (b) calibration plot for glucose sensor, (c) interference study
of ZnCo nanoparticles and (d) response curve.
2
O
4
nanoparticles with successive addition of glucose molecules
2
O
4
1
8

Page 19 of 20
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DOI: 10.1039/C5RA11011D
Fig. 6 (a) CVs of ZnCo
2
4
O nanoparticles in 0.1 M NaOH solution with different concentration
of dopamine (concentration of glucose varies from 100 µM to 1000 µM). (b) Obtained anodic
peak current against different concentration of dopamine. (c) CVs at different scan rates in the
presence of 100 µM dopamine, (d) change in oxidation and reduction peak current against square
root of scan rate.
1
9

RSC Advances
Page 20 of 20
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DOI: 10.1039/C5RA11011D
2
Fig. 7 (a) Chrono-amperometric response of ZnCo O4 nanoparticle with successive addition of
dopamine molecule in the presence of 0.1 M NaOH solution at 0.4 V, (b) calibration plot for
dopamine, (c) interference study (d) response curve.
2
0