Ni nanoparticles decorated titania nanotube arrays as efficient nonenzymatic glucose sensor

Article abstract of DOI:10.1016/j.electacta.2012.05.079

A novel nonenzymatic glucose sensor was developed based on the Ni nanoparticles-loaded TiO₂ nanotube arrays (Ni-NPs/TiO ₂NTs). The Ni-NPs/TiO₂NTs nanocomposites were prepared first by anodization of Ti foil, followed by pulsed electrodeposition method (PED) and characterized by SEM, XRD and XPS respectively. The results showed that spherical Ni nanoparticles were well dispersed and embedded in the TiO ₂NTs. The electrochemical measurements presented that the activated Ni-NPs with a diameter of 40 nm displayed high electrocatalytic activity for the oxidation of glucose and a good sensitivity of 700.2 μA mM^-1 cm^-2 at applied potential 0.6 V, with detection limit of 2 μM (S/N = 3), and good linear range (from 0.004 to 4.8 mM). Such high sensitivity was attributed to the large surface area of the highly dispersed nanoparticles for electrocatalytic reaction and the fast electron transfer in the TiO ₂NTs electrode. The good analytical performance, low cost and simple preparation method make this novel electrode material promising for the development of effective glucose nonenzymatic glucose sensor.

Full text of DOI:10.1016/j.electacta.2012.05.079

Electrochimica Acta 76 (2012) 512–517
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Electrochimica Acta
journal homepage: www.elsevier.com/locate/electacta
Ni nanoparticles decorated titania nanotube arrays as efficient nonenzymatic
glucose sensor
Shujuan Yua, Xiao Pengb,∗, Guozhong Caoc, Ming Zhoua, Lei Qiaoa, Jianyu Yaoa, Huichao Hea
a College of Chemical Engineering, Chongqing University, Chongqing 400044, China
b College of Physics, Chongqing University, Chongqing 400044, China
c Department of Materials Science & Engineering, University of Washington, Seattle, WA 98195, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel nonenzymatic glucose sensor was developed based on the Ni nanoparticles-loaded TiO2 nan-
otube arrays (Ni-NPs/TiO2NTs). The Ni-NPs/TiO2NTs nanocomposites were prepared first by anodization
of Ti foil, followed by pulsed electrodeposition method (PED) and characterized by SEM, XRD and XPS
respectively. The results showed that spherical Ni nanoparticles were well dispersed and embedded in
the TiO2NTs. The electrochemical measurements presented that the activated Ni-NPs with a diameter
of 40 nm displayed high electrocatalytic activity for the oxidation of glucose and a good sensitivity of
700.2 ␮A mM−1 cm−2 at applied potential 0.6 V, with detection limit of 2 ␮M (S/N = 3), and good lin-
ear range (from 0.004 to 4.8 mM). Such high sensitivity was attributed to the large surface area of the
highly dispersed nanoparticles for electrocatalytic reaction and the fast electron transfer in the TiO2NTs
electrode. The good analytical performance, low cost and simple preparation method make this novel
electrode material promising for the development of effective glucose nonenzymatic glucose sensor.
© 2012 Elsevier Ltd. All rights reserved.
Received 23 December 2011
Received in revised form 19 May 2012
Accepted 25 May 2012
Available online 2 June 2012
Keywords:
Glucose sensor
Ni nanoparticles
TiO2 nanotube arrays
Nonenzymatic
Electrocatalysis
1. Introduction
Recently, TiO2 nanotube arrays (TiO2NTs) fabricated by anodiza-
tion of titanium substrate have been studied directly for biosensor
The unique and fascinating properties of nanostructured mate-
rials have attracted tremendous attention among scientists to
explore the full potential to use them in sensor applications.
Glucose biosensors, as the most popular biosensors, have been
extensively investigated due to their important applications in clin-
ical diagnosis, pharmaceutical analysis and food industry [1,2].
Based on the electrochemical method, enzyme-involved glucose
sensors have been widely studied because of its high selectivity
and sensitivity [3–5]. The activity of enzyme, however, is easily
influenced by temperature, humidity and chemical environment
(e.g., pH), which will cause the instability of the biosensor [6]. To
address this problem, nonenzymatic glucose sensors consisting of
metal nanoparticles/carbon nanotubes (CNTs) aroused interest in
many studies. By unique properties of metal nanoparticles such
as enhancing mass transport, high catalysis and increasing sur-
face areas, various metal nanoparticles modified electrode such as
Pt [7–9], Au [10,11], Ag [12], Cu [13,14], Ni [15,16], Pd [17], alloy
[18–20] exhibited high electrocatalytic activity for the oxidation of
glucose. It was also well-known that the performance of the sensor
heavily relies on the matrix CNTs properties, such as its excellent
electron transfer rate and electrocatalytic activities [21,22].
applications [23,24] or used as the supporting electrode for loading
[25,26] and dispersing metal nanoparticles for sensor applications
[27,28]. As an active matrix, TiO2NTs possess high specific surface
area and well-aligned nanostructures with good adhesion to the
substrate. In addition, each channel of a nanotube on the TiO2NTs
electrode serves as an independent nano-sized reaction chamber,
metal nanoparticles adsorbed onto the surface both sides of nano-
tubes retain high specific surface area. Most importantly, according
to our previous studies, the average apparent heterogeneous elec-
tron transfer rate constant (k) was 2.18 × 10−3 cm/s for TiO2NTs
modified by surface defects. This result can match with the electron
transfer rate constant of carbon nanotubes (7.53 × 10−4 cm s−1
)
[29,30]. Furthermore, TiO2NTs have superior bio-affinity. There-
fore they are very promising supporting matrix for loading metal
nanoparticles for the development of nonenzymatic glucose sen-
sors.
Ni-based nonenzymatic sensors were extensively investigated
for electrocatalytic oxidation of glucose [15,31]. The oxidation
processes are catalyzed by the Ni-based sensors through the
formation of a high-valent, oxyhydroxide species (NiOOH) in
alkaline medium. Most Ni-based sensors were prepared by modi-
fying electrodes with Ni nanoparticles, such as electrospinning Ni
nanoparticles on carbon nanofibers or dispersing Ni nanoparticles
in disordered graphite-like carbon [15,32]. Such Ni nanoparticles-
based electrode demonstrated drastic improvements in terms of
∗
Corresponding author. Tel.: +86 23 65678362; fax: +86 23 65102031.
E-mail address: xiaopeng@cqu.edu.cn (X. Peng).
0013-4686/$ – see front matter © 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.electacta.2012.05.079

S. Yu et al. / Electrochimica Acta 76 (2012) 512–517
513
glucose detection sensitivity, compared to the Ni plate. But the
2.3. Electrochemical measurements
agglomeration of Ni nanoparticles remained a big challenge [15,32].
In addition, the stability and catalytic activity of the nanoparticles
depended strongly on the size, morphology, and distribution of the
nanoparticles. It remains another great challenge to minimize the
agglomeration of Ni nanoparticles, so as to improve their catalytic
activities for the development of Ni nanoparticles-based glucose
sensor.
This paper reports for the first time the fabrication of highly
dispersed Ni nanoparticles in TiO2NTs (Ni-NPs/TiO2NTs) as a trans-
ducer for a nonenzymatic glucose sensor. The fabrication process
mainly includes two steps: The first step is the anodic growth of
TiO2NTs from a Ti foil and doping surface oxygen vacancies by
annealing method, while the second step is the pulse electrode-
position (PED) of well dispersed Ni nanoparticles into TiO2NTs. In
comparison with conventional electrodeposition with a constant
DC current, PED favors the initial nucleation with much increased
number of nuclei per unit surface area, resulting in many tiny sized
nanoparticles deposited [33,34]. It was demonstrated that TiO2NTs
doped with oxygen vacancies could be an inexpensive alternative
to carbon nanotubes as support for the metal nanoparticles cata-
lysts. The Ni-NPs/TiO2NTs electrode displayed high sensitivity, fast
response and a wide linear range for glucose detection. The size
effect of Ni nanoparticles of the sensor was also studied.
Electrochemical measurements were performed using CHI660C
(Shanghai, China) with a three electrode system consisting of
the prepared electrode as working electrode, a platinum wire as
counter electrode and an Ag/AgCl (sat. KCl) as reference elec-
trode. Firstly, before glucose detection, Ni-NPs/TiO2NTs electrodes
(1 cm2) were activated by using successively cyclic sweeps between
0.2 and 0.6 V at 50 mV s−1 in 0.1 M NaOH solution, until a stable
CV profile was obtained. The activated Ni-NPs/TiO2NTs electrodes
were evaluated as a glucose sensor in 0.1 M NaOH solution at room
temperature. Different concentrations of glucose were prepared
in 0.1 M NaOH solution before use. Amperometric curves were
obtained when desired concentration of glucose were successively
added into the cell containing 100 mL of 0.1 M NaOH solution under
stirring.
3. Results and discussion
3.1. Characterization of the Ni-NPs/TiO2NTs
Fig. 1 shows the FESEM images of TiO2NTs before and after incor-
porated by Ni nanoparticles, the deposition times of sample B, C
and D were 20, 25 and 30 min respectively. The average pore diam-
eters of TiO2NTs are about 100 nm and the thickness of the wall is
about 15 nm (Fig. 1A). Oxygen vacancies on TiO2NTs surface created
by annealing treatment can bind molecules or act as preferential
adsorption sites for metallic nanoparticles. Thus, Ni nanoparti-
cles were loaded effectively by PED method in the tubes. With
the increase of deposition time, more and more nickel nanopar-
ticles loaded on TiO2NTs can be observed (Fig. 1B, C and D). At the
same time, the average size of the nanoparticles become larger and
larger increased from about 20 to 85 nm, which is attributed to be
inclined to reduce the surface energy of the nanoparticles for the
further nucleation and growth of Ni. As can be seen from inset of
Fig. 1B, highly dispersed Ni nanoparticles are evenly distributed on
the side wall of TiO2NTs. In addition, because of the unique struc-
ture of TiO2NTs, Ni nanoparticles embedded in TiO2NTs tubes have
higher surface area than those loaded on a flat electrode. Thus Ni
nanoparticles modified TiO2NTs have more active sites for detect-
ing glucose.
Fig. 2A shows the XRD pattern of TiO2NTs (i) and Ni-
NPs/TiO2NTs (ii) respectively. The peak with 2␪ of 25.3◦ is assigned
to an anatase crystal structure of TiO2NTs (Fig. 2A(i)). After elec-
trodeposition, the diffraction peaks at 44.5◦ and 51.8◦ correspond
to Ni (1 1 1) and (2 0 0), respectively (Fig. 2A(ii)). XPS measure-
ment was carried out to further confirm the composition of Ni
nanoparticles. As demonstrated in Fig. 2B, the Ni 2p3/2 XPS peaks
(and the associated satellites) located at binding energies of 852.7
and 855.6 eV (satellite at 861.5 eV with respect to the main sig-
nal) correspond to metallic Ni and Ni(OH)2, respectively, which is
in agreement with the results of a previous report on nanocrys-
talline Ni coatings [37], indicating that the presence of metallic Ni
and Ni(OH)2 on the surface of as-prepared sample. This is because
with the increase of the deposition time, hydrogen evolution reac-
tion on the surface of electrode leaded to the increase of OH−
concentration in electrolyte solution. Simultaneously, Ni absorbed
water molecules reacted with OH− and produced nickel hydrox-
ide passive films on nanoparticle surface [37]. But due to the small
quantity, the Ni(OH)2 could not be detected by the XRD measure-
ment. So the nanoparticles were composed by a large amount of
nickel and a small quantity of Ni(OH)2.
2. Experimental
2.1. Reagents and apparatus
Titanium foil (purity: 99.9% Ti, 0.5 mm thick) were purchased
from Goodfellow Cambridge Ltd. Glucose, ascorbic acid (AA) and
uric acid (UA) were purchased from Sigma and used without fur-
ther purification. Hydrofluoric acid (HF, 40%), boracic acid (H3BO3),
nickel sulfate hexahydrate (NiSO4·6H2O) and nickel chloride hex-
ahydrate (NiCl2·6H2O) were purchased from ChuanDong Ltd. All
Chemicals were of analytical grade and without further purifica-
tions. All the solutions were prepared with deionized water.
2.2. Preparation of Ni-NPs/TiO2NTs
Well-aligned titania nanotube arrays were prepared by the
anodization method [35]. The growth conditions used in this work
are similar to those reported in our earlier publications [31]. The
as-anodized TiO2 nanotubes were annealed in a tube furnace
under a flow of dry nitrogen atmosphere with a heating rate of
4 ◦C min−1 and a dwelling time of 3 h at 400 ◦C. Ni nanoparti-
cles were electrodeposited into the annealed TiO2NTs electrode
by PED [36]. Deposition experiments were performed in a three-
electrode system (TiO2NTs as a working electrode, nickel plate
as a counter electrode and Ag/AgCl electrode as a reference elec-
trode). The electrolyte consisted of 300 g/L NiSO4·6H2O, 45 g/L
NiCl2·6H2O, 37 g/L H3BO3, pH = 4.4 and the temperature was kept
at 38 ◦C. Pulse electrodeposition parameters include negative cur-
rent (−160 mA cm−2, 8 ms) and positive current (160 mA cm−2
,
2 ms), current off-time (1000 ms), and deposition time (20 min,
25 min and 30 min). The electrodes deposited for 20 min, 25 min
and 30 min are denoted as sample B, sample C and sample D respec-
tively. After deposition, the Ni-NPs/TiO2NTs were first sealed with
epoxy resin leaving an open area of 1 cm2 as the prepared electrode.
The as-prepared Ni-NPs/TiO2NTs were characterized by scan-
ning electron microscopy (SEM, Nova 400 Nano-SEM, 20 kV),
X-ray diffraction (XRD, Shimadzu ZD-3AX, Cu K␣ radiation) and
XPS (ESCALAB 250, Thermo Fisher Scientific) respectively. Elec-
trodeposition experiments were carried out on Autolab PGSTAT30
workstation.
Incorporation of nanoparticles into TiO2NTs by chemical
bath method and electrochemical deposition method has been
reported [38,39]. However, deposition of highly dispersed metal

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S. Yu et al. / Electrochimica Acta 76 (2012) 512–517
Fig. 1. FESEM images of TiO2NTs (A) and Ni-NPs/TiO2NTs deposited for different time: (B) 20 min; (C) 25 min; (D) 30 min. Inset: the cross-sectional FESEM image of sample
C.
nanoparticles into the nanochannels of TiO2NTs is difficult to
achieve because of the greater inertness and small size of these
channels. Here a simple and effective way was introduced. The
first stage was associated with the reduction of TiO2NTs surface
by annealing method to create oxygen vacancies and increase
metal nucleation. For example, Besenbacher et al. [40] reported that
oxygen vacancies allowed for the stabilization of gold monomers
and gold trimers. This means that metal clusters readily nucleate
homogeneously on reduced TiO2NTs and form highly dispersed
nanocrystals. The second procedure involved the application of
PED technique. In electrochemical deposition process, the fac-
tors that influence the formation of new crystals include (i) high
adatoms population, (ii) high overpotential and (iii) low surface
diffusion rate. By employing high peak current density (Ip) in PED
method, the crystallization overpotential was increased, which in
turn improved the nucleation rate resulting in finer crystals.
3.2. Electrocatalytic oxidation of glucose at activated
Ni-NPs/TiO2NTs
It was reported that the nickel-based catalysts exhibited high
electrocatalytic activity toward the oxidation of organic molecules
in alkaline medium, this effect involved electron transfer mediation
by Ni(OH)2/NiOOH redox couple in the oxide film at the electrode
surface. Moreover, most oxidizable organic compounds were found
to oxidize at the same potential and this potential coincided exactly
with that at which the surface of the nickel electrode becomes
oxidized. Thus, to form more Ni2+/Ni3+ redox couples on the
Fig. 2. (A) XRD patterns of TiO2NTs (i) and Ni-NPs/TiO2NTs (ii). (B) XPS spectra of Ni-NPs/TiO2NTs at the peak Ni 2p3/2
.

S. Yu et al. / Electrochimica Acta 76 (2012) 512–517
515
Fig. 3. (A) CVs of as-prepared Ni-NPs/TiO2NTs in 0.1 M NaOH solution at the scan rate of 50 mV s−1 for 50 cycles. (B) CVs of activated Ni-NPs/TiO2NTs in the absence and
presence of 0.5 mM, 1 mM glucose respectively in 0.1 M NaOH solution. Inset: CVs of TiO2NTs in 0.1 M NaOH solution in the absence and presence of 1 mM glucose. Scan rate:
50 mV s−1
.
Ni-NPs, the as-prepared Ni-NPs/TiO2NTs were first activated in
0.1 M NaOH.
be due to the glucose degradation at the bare TiO2NTs. While
the anodic current response for the activated Ni-NPs/TiO2NTs in
presence of 1 mM glucose was about 559 ␮A so that the activated
nanoparticles played a significant role in electrocatalytic detection
of glucose.
The sensing mechanism of the electrode is schematically shown
in Fig. 4. In alkaline solution, Ni3+ formed on the nanoparticles sur-
face rapidly oxidized glucose to glucolactone. At the same time,
the consumption of Ni3+ species and the production of Ni2+ species
resulted in the increase of oxidation peak current and the decrease
of reduction peak current. Here the Ni3+ species might act as an
electron-transfer mediator. The response mechanism of the acti-
vated Ni-NPs/TiO2NTs to electrochemical oxidation of glucose can
be simply expressed as [41]:
Fig. 3A presents the consecutive cyclic voltammetric of the Ni-
NPs/TiO2NTs (sample C) in 0.1 M NaOH solution at a scan rate of
50 mV s−1. The first cyclic voltammetric corresponded with the
oxidation of Ni to Ni(OH)2 in alkaline solution, then Ni(OH)2 was
progressively oxidized to NiOOH with the increase of scanning
cycles. So, a pair of well-defined redox peaks with cathodic peaks
at 326 mV and the anodic peaks at 499 mV was observed in the CV
results, corresponding to the Ni2+/Ni3+ redox couples. The anodic
and cathodic peaks current increased as the cycle number increased
and then a current plateau and stable voltammetric response was
obtained after 50 scanning cycles, implying that the oxidization of
Ni-NPs/TiO2NTs reached a steady state. The obtained stable anodic
current was about 1.686 mA, the larger current may be attributed to
a good electrochemical performance of anatase TiO2NTs annealed
in N2 and high loading amount of Ni nanoparticles inside the tubes.
Fig. 3B shows CVs response of the activated Ni-NPs/TiO2NTs
(sample C) in 0.1 M NaOH solution containing different concentra-
tions of glucose. One pair of well-defined redox peaks was observed
at 336 mV and 499 mV in the absence of glucose (black line), which
could be attributed to Ni2+/Ni3+ redox group forming in the alkaline
medium. When 0.5 mM glucose was addition to the NaOH solution,
notable enhancement of the anodic current could be observed, and
the voltammetric response increased with a rising concentration of
glucose. Therefore, the activated Ni-NPs/TiO2NTs exhibited elec-
trocatalytic performance for oxidation of glucose as expected. In
order to understand if the bare TiO2NT was involved in the electro-
catalytic process, CV experiment was also performed at the bare
TiO2NTs in the absence and presence of 1 mM glucose (Fig. 3B,
inset). The result showed that there was a mild current response
after the addition of glucose and no obvious redox peaks were
observed for the bare TiO2NTs. The weak current difference might
Ni(OH)2 + OH− → NiO(OH) + H2O + e−
(1)
(2)
NiO(OH) + glucose → Ni(OH)2 + glucolactone
3.3. Amperometric responses of glucose at activated
Ni-NPs/TiO2NTs
The amperometric responses of Ti foil, bare TiO2NTs and acti-
vated Ni-NPs/TiO2NTs for a successive addition of 0.5 mM glucose
at 50 s intervals in 0.1 M NaOH at optimal potential of 0.6 V are
shown in Fig. 5A. No obvious response current of Ti foil and
bare TiO2NTs can be observed. As expected, the activated Ni-
NPs/TiO2NTs produced significantly response signals. This obvious
response concurred with high electrocatalysis of activated Ni
nanoparticles.
Fig. 5B shows the amperometric responses for the successive
additions of 10 ␮M glucose in 0.1 M NaOH solution at 0.6 V of the
activated Ni-NPs/TiO2NTs deposited under different times respec-
tively. It was observed that the electrodes responded quickly to the
Fig. 4. Schematic representation of activated Ni-NPs/TiO2NTs and its glucose sensing mechanism.

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S. Yu et al. / Electrochimica Acta 76 (2012) 512–517
Fig. 5. Amperometric responses of Ti, bare TiO2NTs and activated Ni-NPs/TiO2NTs for successive additions of 0.5 mM glucose in 0.1 M NaOH solution at 0.6 V, respectively.
(B) Amperometric responses for successive additions of 10 ␮M glucose in 0.1 M NaOH solution at 0.6 V of activated Ni-NPs/TiO2NTs deposited for different times: 20 min,
25 min, and 30 min respectively.
change of glucose concentration and reached a steady-state signal
within 5 s. Moreover, the size effect of Ni nanoparticles for the oxi-
dation of glucose was studied. The current response of sample C to
10 ␮M glucose was about 25 ␮A, which was significantly higher
than those of the other two electrodes. It should be noted that
the Ni nanoparticles of sample D had the greatest size (∼85 nm)
and deposition quantity, while the sample B had the smallest size
(∼20 nm) and quantity. Thus, it could be deduced both the depo-
sition quantity and nanoparticles size obviously influenced the
respond of the electrode, more nickel quantity was not always help-
ful for the response. It was reported that the catalytic performance
of nanomaterial was related on surface effects due to boundary con-
ditions, which depended on the surface-to-volume ratio, the shape
and size [42]. For example, the catalytic activity of Au nanoparti-
cles increased with the decrease of the particle size in the certain
range [43]. It was shown from the Fig. 1 that the Ni nanoparti-
cles size became larger and larger with the increase of deposition
time, which leaded to the decrease of specific surface area of Ni
nanoparticles and then reduced catalysis. Although sample B had
the smallest particle size, its deposition quantity was very low due
to the short deposition time, thus its catalytic activity was not as
high as sample C.
Fig. 6A shows the amperometric responses of the activated
Ni-NPs/TiO2NTs (sample C) upon successive addition of various
concentrations of glucose at the applied potential of 0.6 V. The
response time was less than 5 s, indicating a good catalytic prop-
erty of the electrode. The corresponding calibration curve (Fig. 6A,
right inset) was linear from 0.004 to 4.8 mM with a sensitivity of
700.2 ␮A mM−1 cm−2 and a detection limit of 2 ␮M (S/N = 3).
The sensing performance of the sensor was compared with the
previously reported glucose sensors based on the utilization of Ni
nanoparticles modified electrodes as shown in Table 1. It was con-
cluded that our activated Ni-NPs/TiO2NTs has a higher sensitivity
and a wider linear range. This result also verified that TiO2NTs could
be used as a good substrate material for sensors. Moreover, the
sensitivity of the Ni-NPs/TiO2NTs was greatly higher than that of
Ni layers modified TiO2NTs (200 ␮A mM−1 cm−2) [44]. The higher
sensitivity was attributed to a good conductivity and unique surface
structure of TiO2NTs and high electrocatalytic activity of dispersed
Ni nanoparticles with high surface areas.
3.4. Anti-interferences, reproducibility and stability of activated
Ni-NPs/TiO2NTs
According to the above results, we chose the activated Ni-
NPs/TiO2NTs prepared at deposition time of 25 min (sample C) to
obtain the sensing performance. The influence of the applied poten-
tial on the response of the sensor was investigated. Current-time
curves were recorded at different applied potential in successive
addition 0.5 mM glucose (not shown). The results showed that
the best sensing respond was observed at the applied potential of
0.6 V.
The presence of electroactive compounds in real blood, such
as AA and UA, interferences the determination of glucose. There-
fore, we examined the electrochemical response of UA and AA
at activated Ni-NPs/TiO2NTs. The experiment was carried out by
adding 1.0 mM glucose in 0.1 M NaOH followed by 0.01 mM AA and
0.01 mM UA. As shown in Fig. 6B, the electroactive species did not
cause interference significantly for the determination of glucose.
Fig. 6. (A) Typical amperometric response of activated Ni-NPs/TiO2NTs (sample C) towards various concentrations of glucose at 0.6 V in 0.1 M NaOH solution; left inset: the
amplified response curve, right inset: the linear calibration curve. (B) Interference test of the activated Ni-NPs/TiO2NTs to the successive addition of 1 mM glucose, 0.01 mM
AA, and 0.01 mM UA.

S. Yu et al. / Electrochimica Acta 76 (2012) 512–517
517
Table 1
Comparison of the performance parameters of the activated Ni-NPs/TiO2NTs (sample C) and Ni nanoparticles modified electrodes.
Electrode materials
Sensitivity
Linear range
Detection limit
Ref.
(mmol l−1
)
(␮mol l−1
)
Ni nanoparticle-loaded carbon nanofiber paste electrode
Ni nanoparticles embedded in a graphite-like carbon film electrode
Ni–Pd nanoparticles 3D ordered silicon microchannel plate
Ni nanoparticles modified TiO2NTs electrode
0.003 mA mmol−1 cm−2
Not given
0.002–2.5
1
0.02
5
[15]
[32]
[45]
0.00005–0.5
Not given
0.004–4.8
0.081 mA mM−1
0.700 mA mM−1 cm−2
2
Present work
These results implied that the activated Ni-NPs/TiO2NTs has a good
anti-interference ability.
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Six successive measurements of glucose on one Ni-NPs/TiO2NTs
yielded an R.S.D. of 4.1%, indicating that the sensor was repro-
ducible. The stability was studied by successively scanning in 0.1 M
NaOH solution after storing 20 days. The stable oxidation current
decreased to 80.3% of its initial response.
4. Conclusions
An enzyme-free glucose sensor was fabricated by pulsed elec-
trochemical deposition of Ni nanoparticles into highly ordered TiO2
nanotubes. Due to unique structure of the nanotubes and high sur-
face areas of the deposited nanoparticles, Ni-NPs with a diameter
of 40 nm exhibited high electrocatalytic activity for the glucose
electro-oxidation. The activated Ni-NPs/TiO2NT demonstrated a
detection limit of 2 ␮M, high sensitivity of 700.2 ␮A mM−1 cm−2
and a wide linear range of 4 ␮M to 4.8 mM. The excellent sens-
ing performance, low cost and simple fabrication procedure may
potentially pave the way for large scale production of inexpensive,
effective and highly sensitive glucose sensors.
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Acknowledgement
This work was supported by the Fundamental Research Funds
for the Central Universities (Project No. CDJZR10100021).
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