Engineering the valence state of ZIF-67 by Cu2O for efficient nonenzymatic glucose detection

Article abstract of DOI:10.1039/d0tb00094a

The valence state regulation of Co-based electrocatalysts is extremely important and greatly challenging to enhance the electrochemical performance toward glucose oxidation. Herein, Cu₂O?ZIF-67 composites with fine-tuned valence states were rationally constructed for boosting glucose oxidation. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) analysis confirm that the content of the high valence state Co (Co³⁺) in Cu₂O?ZIF-67 is much higher than that in the individual ZIF-67 due to the synergistic effects between ZIF-67 and Cu₂O. As a result, Co³⁺-rich Cu₂O?ZIF-67 composite exhibits remarkable activity toward glucose electro-oxidation with two linear response ranges of glucose concentration, from 0.01 to 10 mM and 10 to 16.3 mM, high sensitivities of the linear ranges (307.02 and 181.34 μA mM^-1 cm^-2) as well as a low detection limit (6.5 μM). This research provides a novel avenue for the progress of highly efficient electrocatalysts for nonenzymatic glucose oxidation.

Full text of DOI:10.1039/d0tb00094a

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Engineering Valence State of ZIF-67 by Cu O for Efficient
2
Nonenzymatic Glucose Detection
Received 00th January 20xx,
Accepted 00th January 20xx
Nian Yang, Kailu Guo, Yanwen Zhang, Cailing Xu*
DOI: 10.1039/x0xx00000x
The valence state regulation of Co-based electrocatalysts is extremely important and greatly challenging to enhance the
electrochemical performance for glucose oxidation. Herein, Cu
2
O@ZIF-67 composite with fine-tuned valence state were
rationally constructed for boosting glucose oxidation. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV)
3
+
analysis confirm that content of high valence state Co (Co ) in Cu
2
O@ZIF-67 is much higher than that in individual ZIF-67
3
+
due to the synergistic effects between ZIF-67 and Cu O. As a result, Co -rich Cu O@ZIF-67 composite exhibits remarkable
2
2
activity to glucose electro-oxidation with two linear response ranges of glucose concentration, from 0.01-10 mM and 10-
6.3 mM, two sensitivities of determination regions mentioned above (307.02 and 181.34 μA mM-1 cm ), as well as a low
-2
1
detection limit (6.5 μM). This research provides a novel avenue in progress of high-efficient electrocatalysts for non-
enzymatic glucose oxidation.
of non-enzymatic glucose sensor.11-13 For instance, Zhao’s
group manufactured a MIL-53(NiFe) MOF, exhibiting enhanced
Introduction
1
1
selectivity in alkaline media. Xu's group prepared a Cu-based
MOF for detecting glucose, which showed a favorable
Glucose is a significant biomolecule for sustaining human’s
daily activities, while excess glucose in human blood result in
metabolic disorder causing many diseases (e.g., diabetes
mellitus).1 Therefore, speedy and exact ascertainment of its
concentration in blood is important in the region of clinical
diagnosis. Currently, a large number of methods have been
-1
-2
sensitivity (89 μA mM cm ) in linear response extent of 0.06
1
2
μM - 5 mM. Although MOFs as sensing materials have made
some achievements, there is still room to optimize the
performance of MOF-based electrocatalysts for nonenzymatic
glucose determination owing to the narrow detection range,
,2
2
,3
realized in glucose determination. Among them, enzymatic
electrochemical sensors manifest satisfactory sensitivity and
selectivity, whereas natural enzymes are subjected to high
price, poor stability as well as sophisticated immobilization
procedure.4 Therefore, it is necessary to find electrocatalysts
with desirable characteristics such as high efficiency, excellent
durability, and low price for non-enzymatic glucose
determination.
1
3-15
low sensitivity and poor stability.
As is well known, MOFs’
electrocatalytic activity is heavily related to the conductivity of
materials and the electronic structures of catalytic metal
1
6
centers , while valence states of metal centers in MOFs
possess a considerable influence on the electronic structure
,5
1
7-19
and charge distribution.
Thus, in order to acquire highly
efficient catalysts for glucose electro-oxidation, it might be an
operative approach to adjust metal centers’ valence states in
MOFs by means of the electronic interaction between MOFs
and foreign materials in the synthesis process. However, there
is few research records in literatures.
In recent decade, metal-organic frameworks (MOFs),
formed by organic ligands and metal ions via strong
coordination bonds, have captured great attentions in
catalysis, separations, gas storage, drug delivery as well as
sensors, due to the distinguished properties, such as
permanent porosity, adjustable pore structure, as well as high
flexibility for design. Especially, MOFs with high specific
surface areas have the superior enzyme-like catalytic activity
for a series of substrates, which makes it possible for them to
Besides MOFs, electrocatalysts based on transition metal
oxides (NiO, Co
studied for sensor applications.
Cu O is a hopeful contender in manufacture of electrochemical
sensors by reasons of the natural abundance, nontoxicity, low
3 4
O , CuO, and ZnO, etc.) have been widely
2
0-23
Among these metal oxides,
6
-8
2
2
4-26
cost and remarkable stability.
2
However, pristine Cu O is
9
,10
be used as nanozymes to design different types of sensors.
Therefore, some research groups try to apply MOFs to the field
not very sensitive to glucose oxidation. In order to obtain
highly efficient catalysts for glucose sensor, a common
strategy is to design composites with modulated composition
2
6-28
which can provide optimum process parameters.
For
State Key Laboratory of Applied Organic Chemistry, Laboratory of Special Function
Materials and Structure Design of the Ministry of Education, College of Chemistry
and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China.
E-mail: xucl@lzu.edu.cn
Electronic Supplementary Information (ESI) available. See
DOI: 10.1039/x0xx00000x
instance, Zhou et al. prepared RGOs-Cu
showing good performance as a glucose sensor. Long's group
2
O nanocomposites,
27
2
synthesized Au@Cu O core-shell structure through chemical
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deposition process for glucose determination.28 Although
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DOI: 10.1039/D0TB00094A
some progress has been made in Cu O-based composites, the
2
current studies mainly focus on the improvement of electronic
conductivity by combining with various conductive materials. It
is rare to investigate the integrated interaction between
individual components, which may have significant effects on
the ionic valence, electronic structure and redox potential of
the composites. Based on the above analysis, it is expected to
achieve excellent performance for electrocatalytic oxidation of
glucose by constructing a composite structure of Cu
MOFs with strong interaction.
2
O and
Herein, a core-shell structure of Cu
prepared through a simple approach. In this hybrid, due to the
electronic interaction between Cu O and ZIF-67, the content of
Co increases obviously, which is helpful to the transition of
2
O@ZIF-67 was
Figure 1. (a) SEM image of Cu
Cu
mapping images of Cu
2
O. (b) TEM image of ZIF-67. (c) TEM image of
2
O@ZIF-67. (d) XRD patterns of Cu
O@ZIF-67.
2 2
O, ZIF-67 and Cu O@ZIF-67. (e) EDX
2
2
3
+
3
+
4+
Co to Co , sequentially beneficial to the oxidation of
demonstrates the existence of Cu and Co, respectively. For
Cu O@ZIF-67, Co element can be obviously found, but the
characteristic peak of Cu becomes very weak in the
composites due to the low loading of Cu O and a quite shallow
glucose.2
9-31
2
As is expected, the as-prepared Cu O@ZIF-67
2
exhibits excellent performance for glucose oxidation such as
wider linear range, higher sensitivity, better selectivity, and
more superior practical application than that of individual
counterpart and previously reported results. All these results
manifest the significance of engineering valence states in
designing MOF-based electrocatalysts on non-enzymatic
glucose sensors.
2
XPS intake thickness (~5 nm). In Figure 2a, the peaks at 952.1
+
and 932.3 eV for Cu
2
O belong to Cu as well as the peaks at
2+
9
54.2 and 934.5 eV should be the characteristic peaks of Cu
O.32-
species, which is ascribed to the partial oxidization of Cu
2
35
+
2 2
Compared with Cu O, the peaks of Cu for Cu O@ZIF-67
negatively shift about 0.3 eV. Interestingly, the peaks located
at 797.3, 795.8, 781.7 and 780.4 eV for ZIF-67 can be indexed
Results and Discussion
2
+
3+
2+
3+
to the Co 2p1/2, Co 2p1/2, Co 2p3/2 as well as Co 2p3/2
,
The scanning electron microscopy (SEM) image of prepared correspondingly (Figure 2b).36-38 For Cu O@ZIF-67 sample,
2
Cu
2
O is depicted in Figure 1a. The nanocrystals with average these peaks of Co 2p shift to higher binding energies compared
diameter of ~250 nm exhibit cubic shape with sharp faces and with those of pure ZIF-67, implying the strong electronic
3
9,40
highly size uniformity. Figure 1b is the transmission electron interaction between Cu O and ZIF-67.
Besides, the ratio of
2
3
+
2+
microscopy (TEM) image of ZIF-67. A characteristic polyhedral Co /Co can be calculated as 0.52 for ZIF-67 and 0.99 for
shape is observed for ZIF-67 sample and its size is Cu O@ZIF-67, which indicates the substantial increase of Co
3
+
2
approximately 700 nm. Compared with the TEM image of ZIF- in Cu O@ZIF-67 in contrast with that in pure ZIF-67 due to the
2
6
7, it can be found in Figure 1c and Figure S1a,b that Cu
2
2
O NPs synergistic effects between Cu O and ZIF-67. The higher
3
+
are encapsulated by ZIF-67 and distributed homogeneously, content of Co in Cu O@ZIF-67 is helpful to the transition of
revealing the typical core–shell structure of the resultant Co to Co , sequentially beneficial to the oxidation of
2
3
+
4+
2
9-31
products. The EDS spectrum (Figure S1c) of Cu
demonstrates the co-existence of Cu and Co elements. Figure
d presents corresponding XRD patterns of ZIF-67, Cu O and electrocatalytic performance of Cu O, ZIF-67 and Cu O@ZIF-67
Cu O@ZIF-67. All the diffraction peaks of prepared ZIF-67 modified electrodes to the glucose oxidation in alkaline media.
adequately match up with the simulated patterns. For the as- As illustrated in Figure 3a, a broad current response between
synthesized Cu O, peaks at 2θ=29.6°, 2θ=36.4°, 2θ=42.3°, 0.1 and 0.6 V can be viewed for Cu O electrode, which may be
θ=61.4° and 2θ=73.5° are ascribed to (110), (111), (200), ascribed to a reversible transition of Cu to Cu and Cu to
2
O@ZIF-67 glucose.
Firstly, cyclic voltammetry (CV) is applied to evaluate the
1
2
2
2
2
2
2
+
2+
2+
2
3
+ 41
(220) as well as (311) crystal faces of Cu
2
2
O (JCPDS:99-0041), Cu . The catalytic activity of Cu O towards the oxidation of
respectively. For Cu O@ZIF-67, another four diffraction peaks glucose is proved by an improved current response when
2
located at 2θ=29.6°, 2θ=36.4°, 2θ=42.3°and 2θ=61.4° can be adding 3 mM glucose (Figure 3b). The possible electro-
observed except for the diffraction peaks of ZIF-67, which are oxidation mechanism of glucose on surface of Cu O is
2
4
2-43
2
characteristic peaks of Cu O. The corresponding elemental described as follows:
+
-
2+
-
mappings (Figure 1e) illustrate the even distribution of Co, C
and N elements over the whole hybrids, while Cu element is
mainly concentrated in the center of the particle. From the
results of TEM, XRD and EDX, it could be inferred that
Cu + OH → Cu + H O + e
(1)
(2)
2
2
+
-
3+
-
Cu + OH → Cu + e
3
+
2+
Cu + glucose → gluconolactone + Cu (3)
For ZIF-67, a pair of redox peaks could be noticed near 0.2V
without glucose, which may be mainly related to the reversible
XPS measurement is performed to research the elemental transition between Co and Co (Figure 3a). Upon the
categories and valence states of prepared samples. As injection of 3 mM glucose (Figure 3b), a slight enhancement
2
Cu O@ZIF-67 core–shell structure is prepared successfully.
2
+
3+
30
depicted in Figure S2, the survey spectra of Cu
2
O and ZIF-67
2
| J. Name., 2012, 00, 1-3
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Figure 2. (a) The high-resolution XPS of Cu 2p for Cu
2 2
O and Cu O@ZIF-67. (b) The
high-resolution XPS of Co 2p for ZIF-67 and Cu O@ZIF-67.
2
of current response indicates the weak catalytic property of
ZIF-67 for glucose electro-oxidation. The possible mechanism
of glucose electro-oxidation on Co-based active materials is
2
,29-31
illustrated by Equations (4), (5) and (6),
2
+
-
3+
-
Co + OH → Co + H
2
O + e
O + e
(4)
(5)
3
+
-
4+
-
Co + OH → Co + H
2
4
+
3+
Co + glucose → gluconolactone + Co (6)
According to the Equations (6), the electro-oxidation
4
+
process of glucose is mainly controlled by Co . Hence, the
poor current response of ZIF-67 in the presence of glucose can
3
+
4+
2
be related to the ignorable Co /Co peak. In contrast to Cu O
and ZIF-67, a strong oxidation peak can be found nearby 0.35 V
except for the obvious current response at around 0.2 V
without glucose for Cu
the conversion of Co and Co . Therefore, the synergistic
2
+
O@ZIF-67, which could be ascribed to
3
4+ 44
effects between Cu
2
O and ZIF-67 are beneficial to the
2
Figure 3. (a) The partial enlarged cyclic voltammogram curves of Cu O, ZIF-67
transformation of Co3+ to Co in the electrocatalytic process and Cu O@ZIF-67 in 1 M KOH without glucose. (b) Cyclic voltammogram curves
4+
2
and cause the negative shift of redox peak potential of Cu
2
O, ZIF-67 and Cu
Inset: CV curves of Cu
voltammogram curves of Cu
concentrations of glucose. Inset: corresponding graph of current density at 0.35
V vs. glucose concentration. (d) Cyclic voltammogram curves of Cu O@ZIF-67 in
2
O@ZIF-67 in 1 M KOH in the presence of 3mM glucose.
O, ZIF-67 and Cu O@ZIF-67 without glucose. (c) Cyclic
O@ZIF-67 in KOH containing varying
3
+
4+
2
2
(
Co /Co ). As mentioned above, the conversion of glucose to
2
1 M
3
+
4+
gluconolactone is primarily dependent on Co /Co . Thus,
when 3 mM glucose is injected in KOH, the largest current
2
response can be obtained for Cu
suggesting the favorable catalytic activity of Cu O@ZIF-67
2
towards the oxidation of glucose. The synergistic effects and
2
O@ZIF-67 (Figure 3b), 1 M KOH with 0.5 mM glucose in case of varying scan rates. Inset: corresponding
graph of peak current density vs. scan rate. (e) The scheme of the synergistic
2
effects and sensing mechanism of Cu O@ZIF-67 toward glucose in KOH solution.
sensing mechanism of Cu
in Figure 3e.
Figure 3c shows the changes of oxidation current against
different glucose concentration for Cu O@ZIF-67. As glucose
concentration gradually increases, current response arises
accordingly. Moreover, the inset displays the linearity of
current intensity at 0.35 V with concentration of glucose,
2
O@ZIF-67 toward glucose is shown
interval of 50 s is shown in Figure 4a. With each injection of
glucose, the enhancement of current response could be
noticed and 95% of steady-level current is achieved within 5-6
2
s for Cu
current response of Cu
concentration enhanced substantially in contrast with that of
ZIF-67 and Cu O, which might benefit from the synergistic
effects of Cu O and ZIF-67. Figure 4b is the corresponding
2
O, ZIF-67 and Cu
2
O@ZIF-67 (Figure S4). However, the
2
O@ZIF-67 towards the same glucose
2
indicating a good anti-poisoning ability of Cu
2
O@ZIF-67
Additionally, CV at changed
scan rates were investigated with 0.5 mM glucose to assess
the reaction kinetics of Cu O@ZIF-67 (Figure 3d). The inset
4
5,46
2
electrode for the intermediate.
calibration curves (current density vs. glucose concentration)
obtained from amperometric tests. The liner range of
2
Cu
that of Cu
2
O@ZIF-67 (0.01-10mM, 10-16.3mM) is more extended than
O (0.1-3.3mM) and ZIF-67 (0.03-5.5mM). The wider
exhibits that oxidative peak current density is linearly
correlated with scan rate over an examined range (1-10 mV/s)
with a correlation coefficient (R ) of 0.99925, implying that the
2
2
linear range may benefit from the easy adsorption,
penetration and desorption of glucose molecules and the
glucose electro-oxidation on surface of Cu
characteristic surface adsorption-controlled process.
For the purpose of obtaining the best electrocatalytic
property of Cu O@ZIF-67 towards the oxidation of glucose, the
2
O@ZIF-67 is a
3
9
4
7
intermediates on Cu
6
2
O@ZIF-67. The sensitivity of Cu
2
O@ZIF-
-1
-2
-1
-2
7 (307.02 μA mM cm , 181.34 μA mM cm ) is the highest
one among three samples (Cu O: 100.70 μA mM cm , ZIF-67:
2
5.53 μA mM- cm ). Notably, sensitivity at lower
-1
-2
2
1
-2
8
applied potential was firstly optimized. In consideration of the
sensitivity and selectivity, 0.55V was selected for pursuant
experiments (Figure S3). The current-time (i-t) curves with
stepwise injection of glucose into 1M KOH at 0.55V with a time
concentration range is more superior than that at higher
concentration range, which may be the result of intermediate
adsorption on electrode surface then hinder further contact
This journal is © The Royal Society of Chemistry 20xx
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Figure 4. (a) Amperometric response of Cu
2
O, ZIF-67 and Cu
2
O@ZIF-67 with
Figure 5. (a) The current response of Cu O@ZIF-67 upon continuing addition of
2
continuing injection of glucose at 0.55V. (b) The corresponding calibration curves
of current density against glucose concentration. (c) Nyquist plots of Cu O, ZIF-67
and Cu O@ZIF-67 in 0.5 M Na SO with 2.5mM [Fe(CN)
] 3-/4-. Inset: the whole
glucose and other interferences. (b) Amperometric response towards 2.5 mM
2
glucose of Cu O@ZIF-67 during 9000 s. (c) The repeatability of Cu O@ZIF-67. (d)
2
2
2
2
4
6
The reproducibility of Cu O@ZIF-67.
2
Nyquist plot of ZIF-67 and the randle equivalent circuit applied to fit the
impedance spectroscopy. (d) Capacitive current density (at -0.1 V) as a function
of scan rate for Cu O, ZIF-67 and Cu O@ZIF-67.
2 2
Table 1 Glucose concentration in practical samples tested by Cu
2
O@ZIF-67.
Detected
values
Reference
values
between glucose molecules and catalysts.39 Besides, the
detection limit of Cu O@ZIF-67 (6.5 μM) is also lower than that
of Cu O and ZIF-67 (52.9 μM for Cu O, 25.8 μM for ZIF-67),
indicating a satisfactory electrocatalytic activity of Cu O@ZIF-
7. In contrast with other copper and cobalt-based
materials (Table S1), the as-prepared Cu O@ZIF-67 displays
2
not only wider linear range but also higher sensitivity.
Furthermore, the electrochemical impedance spectroscopy
Recovery
%)
RSD
(%)
samples
AVG
12.5
11.1
(
2
(
mM)
2.7
12.6
(mM)
2
2
1
2
1
2
12.1
11.2
103
99
2.1
2.7
6
1
1
2.2
1.4
11.2
0.7
1
(
EIS) of ZIF-67, Cu
2 2
O and Cu O@ZIF-67 were studied in 0.5 M
3
-/4-
Na SO with 2.5mM [Fe(CN)
2
4
6
]
at open-circuit voltage to
clearly evaluate the kinetics of charge transfer. As shown in
Figure 4c, ZIF-67 modified electrode exhibits the largest charge
transfer resistance (Rct) caused by poor conductivity of MOFs.
period of 9000 s (Figure 5b). It is evident that only 6.5% of the
initial value is lost, demonstrating a good stability of
Cu O@ZIF-67. The repeatability was analyzed by recording the
2
current response to 1 mM glucose of single electrode stored
under the ambient condition every two days over a period of 1
month. As depicted in Figure 5c, in contrast with the initial
By contrast, Cu
transfer. The similar conductivity can be obtained after the
incorporation of Cu O into ZIF-67, demonstrating the coupling
effect of Cu O and ZIF-67. In order to better explain the
electrocatalytic activity of Cu O, ZIF-67 and Cu O@ZIF-67, the
2
O sample displays the enhanced charge
2
2
value, the current response of Cu
experiment almost keeps constant, verifying an acceptable
long-term durability of Cu O@ZIF-67. To investigate the
reproducibility (Figure 5d) of Cu O@ZIF-67, five electrodes
2
O@ZIF-67 for every
2
2
electrochemical active surface area (ECSA) was assessed.
Double-layer capacitance (Cdl), linearly in proportion to ECSA,
was ascertained in term of linear-fitting CV curves illustrated in
Figure S5.48 As exhibited in Figure 4d, ZIF-67 sample shows the
largest Cdl by reason of the considerable specific surface area
2
2
were prepared separately under the same condition and were
used to detect 1mM glucose. It can be found that the
calculated relative standard deviation (RSD) is less than 4.6%
for these electrodes, which verifies the superior reproducibility
of MOFs. However, the Cdl of Cu
Cu O is encapsulated into ZIF-67, indicating the best intrinsic
activity of Cu O@ZIF-67 towards glucose electro-oxidation.
Therefore, the high-efficient coupling of Cu O and ZIF-67 is a
pivotal factor of the enhanced electrocatalytic activity of
2
O@ZIF-67 is decreased when
2
of Cu
The applicability of Cu
ascertaining glucose concentration in human serum samples.
The results tested by Cu O@ZIF-67 are in agreement with that
2
O@ZIF-67.
2
2
O@ZIF-67 is evaluated by
2
2
Cu
2
O@ZIF-67.
obtained from hospital (Table 1), implying the fabricated
sensor is able to meet the demand of detecting actual samples
with satisfying accuracy and precision.
Figure 5a is the anti-interference performance of
Cu
2 2
O@ZIF-67. It can be obviously observed that Cu O@ZIF-67
displays a remarkable response to glucose and a negligible
response to interfering species, respectively, which suggests a
good specificity of Cu
determination. The stability of Cu
surveying the steady-state current response during a long time
2
O@ZIF-67 for nonenzymatic glucose
Conclusions
2
O@ZIF-67 is testified by
4
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1
1
1
5 Y. Dong, C. Duan, Q. Sheng and J. Zheng, AnalysVtie,w2A0rt1ic9le,O1n4lin4e,
21-529.
6 H. Zhou, M. Zheng, H. Tang, B. Xu, Y. Tang and H. Pang,
Small, 2020, 16, 1904252.
In summary, Cu
prepared via encapsulating pre-synthesized Cu
into ZIF-67. X-ray photoelectron spectroscopy (XPS) and cyclic
2
O@ZIF-67 core-shell structure was
5
DOI: 10.1039/D0TB00094A
2
O nanocubes
3
+
voltammetry (CV) curves demonstrate that content of Co in
Cu O@ZIF-67 is increased compared with that in ZIF-67, which
7 Q. Mu, W. Zhu, X. Li, C. Zhang, Y. Su, Y. Lian, P. Qi, Z. Deng, D.
Zhang, S. Wang, X. Zhu and Y. Peng, Appl. Catal. B Environ.,
2
2
020, 262, 118144.
is helpful to the oxidation of glucose due to the easy transition
of Co3+ to Co4+. Profit from the synergistic effects between
18 E. A. Dolgopolova, A. J. Brandt, O. A. Ejegbavwo, A. S. Duke,
T. D. Maddumapatabandi, R. P. Galhenage, B. W. Larson, O.
G. Reid, S. C. Ammal, A. Heyden, M. Chandrashekhar, V.
Stavila, D. A. Chen and N. B. Shustova, J. Am. Chem. Soc.,
2017, 139, 5201-5209.
Cu
2
O
2
and ZIF-67, Cu O@ZIF-67 presents significant
electrocatalytic performance towards glucose electro-
oxidation in 1 M KOH with desirable linear range, sensitivity as
1
2
2
2
2
9 D. Zhu, C. Guo, J. Liu, L. Wang, Y. Du and S. -Z. Qiao, Chem.
Commun., 2017, 53, 10906-10909.
0 T. Zhu, Y. Zhang, L. Luo and X. Zhao, ACS Appl. Mater.
Interfaces, 2019, 11, 10856-10861.
1 L. Bao, T. Li, S. Chen, C. Peng, L. Li, Q. Xu, Y. Chen, E. Ou and
W. Xu, Small, 2017, 13, 1602077.
2 Y. Zhang, Y. Liu, L. Su, Z. Zhang, D. Huo, C. Hou and Y. Lei,
Sens. Actuators B Chem., 2014, 191, 86-93.
2
well as limit of detection. In addition, Cu O@ZIF-67 also shows
good selectivity and excellent long-term durability. More
importantly, the manufactured sensor is able to ascertain
glucose concentration in practical samples with satisfying
outcomes, which will supply a hopeful pathway for high-
efficient glucose determination.
3 A. Tarlani, M. Fallah, B. Lotfi, A. Khazraei, S. Golsanamlou, J.
Muzart and M. Mirza-Aghayan, Biosens. Bioelectron., 2015,
Conflicts of interest
6
7, 601-607.
2
2
2
2
2
4 J. Lv, C. Kong, K. Liu, L. Yin, B. Ma, X. Zhang, S. Yang and Z.
Yang, Chem. Commun., 2018, 54, 8458-8461.
There are no conflicts to declare.
5 B. Yuan, C. Xu, L. Liu, Q. Zhang, S. Ji, L. Pi, D. Zhang and Q.
Huo, Electrochim. Acta, 2013, 104, 78–83.
Acknowledgements
This research was funded by Natural Science Foundation of
China (NSFC No. 21673105, 21503102, 21701071) and the
Science and Technology Program of Gansu Province of China
6 X. Wu, F. Li, C. Zhao and X. Qian, Sens. Actuators B Chem.,
2
018, 274, 163-171.
7 D. L. Zhou, J. J. Feng, L. Y. Cai, Q. X. Fang, J. R. Chen and A. J.
Wang, Electrochim. Acta, 2014, 115, 103 —108.
8 Y. Su, H. Guo, Z. Wang, Y. Long, W. Li and Y. Tu, Sens.
Actuators B Chem., 2018, 255, 2510-2519.
(Grant No. 17JR5RA194). Besides, we sincerely appreciate the
Electron Microscopy Centre of Lanzhou University for SEM and 29 X. Zhu, S. Yuan, Y. Ju, J. Yang, C. Zhao and H. Liu, Anal. Chem.,
2
019, 91, 10764-10771.
TEM characterizations.
3
3
3
3
0 W. Meng, Y. Wen, L. Dai, Z. He and L. Wang, Sens. Actuators
B Chem., 2018, 260, 852-860.
1 E. Zhang, Y. Xie, S. Ci, J. Jia and Z. Wen, Biosens. Bioelectron.,
References
2
016, 81, 46-53.
2 Y. M. Choi, S. Y. Cho, D. Jang, H. J. Koh, J. Choi, C. H. Kim and
H. T. Jung, Adv. Funct. Mater., 2019, 29, 1808319.
1
S. Chaiyo, E. Mehmeti, W. Siangproh, T. L. Hoang, H. P.
Nguyen, O. Chailapakul and K. Kalcher, Biosens. Bioelectron.,
3 X. Tan, C. Yu, C. Zhao, H. Huang, X. Yao, X. Han, W. Guo, S.
Cui, H. Huang and J. Qiu, ACS Appl. Mater. Interfaces, 2019,
2
018, 102, 113-120.
2
3
4
5
6
7
8
9
1
1
1
1
1
X. Chen, D. Liu, G. Cao, Y. Tang and C. Wu, ACS Appl. Mater.
Interfaces, 2019, 11, 9374–9384
S. H. Liao, S. Y. Lu, S. J. Bao, Y. N. Yu and M. Q. Wang, Anal.
Chim. Acta, 2016, 905, 72–78.
S. L. Zhong, J. Zhuang, D. P. Yang and D. Tang, Biosens.
Bioelectron., 2017, 96, 26-32.
P. Yang, X. Tong, G. Wang, Z. Gao, X. Guo and Y. Qin, ACS
Appl. Mater. Interfaces, 2015, 7, 4772-4777.
1
1, 9904-9910.
3
4 C. Song, Z. Zhao, X. Sun, Y. Zhou, Y. Wang and D. Wang,
Small, 2019, 15, 1804268.
3
3
5 X. An, K. Li and J. Tang, ChemSusChem, 2014, 7, 1086-1093.
6 W. Wang, Y. Lu, M. Zhao, R. Luo, Y. Yang, T. Peng, H. Yan, X.
Liu and Y. Luo, ACS Nano., 2019, 13, 12206-12218.
7 H. Wang, F.-X. Yin, B.-H. Chen, X.-B. He, P.-L. Lv, C.-Y. Ye and
D.-J. Liu, Appl. Catal., B, 2017, 205, 55–67
8 S. Li, S. Peng, L. Huang, X. Cui, A. M. Al-Enizi and G. Zheng,
ACS Appl. Mater. Interfaces, 2016, 8, 20534-20539.
9 Y. Wu, X. Liu, D. Han, X. Song, L. Shi, Y. Song, S. Niu, Y. Xie, J.
Cai, S. Wu, J. Kang, J. Zhou, Z. Chen, X. Zheng, X. Xiao, G.
Wang, Nat. Commun., 2018, 9, 1425-1434.
0 Q. Yao, ZH. Lu, W. Huang, X. Chen and J. Zhu, J. Mater. Chem.
A, 2016, 4, 8579-8583.
1 S. Shahrokhian, E. K. Sanati and H. Hosseini, Biosens.
Bioelectron., 2018, 112, 100-107.
3
3
3
J. Liu, L. Chen, H. Cui, J. Zhang, L. Zhang and C. -Y. Su, Chem.
Soc. Rev., 2014, 43, 6011-6061.
X. Wang, X. Lu, L. Wu and J. Chen, Biosens. Bioelectron.,
2
015, 65, 295-301.
Z. Wang, M. Gui, M. Asif, Y. Yu, S. Dong, H. Wang, W. Wang,
F. Wang, F. Xiao and H. Liu, Nanoscale, 2018, 10, 6629-6638.
L. Qin, X. Wang, Y. Liu and H. Wei, Anal. Chem., 2018, 90,
4
4
9
983-9989.
0 X. Zhang, G. Li, D. Wu, X. Li, N. Hu, J. Chen, G. Chen and Y.
Wu, Biosens. Bioelectron., 2019, 137, 178-198.
1 L. Zhang, X. Ma, H. Liang, H. Lin and G. Zhao, J. Mater. Chem.
B, 2019, 7, 7006-7013.
2 Y. Sun, Y. Li, N. Wang, Q. Q. Xu, L. Xu and M.
Lin, Electroanalysis, 2018, 30, 474–478
3 X. Xiao, S. Zheng, X. Li, G. Zhang, X. Guo, H. Xue and H. Pang,
J. Mater. Chem. B, 2017, 5, 5234-5239.
4 Y. Wen, W. Meng, C. Li, L. Dai, Z. He, L. Wang, M. Li and J.
Zhu, Dalton Trans., 2018, 47, 3872-3879.
4
4
2 L. Wu, Z. Lu and J. Ye, Biosens. Bioelectron., 2019, 135, 45-49.
3 X. Zhang, J. Luo, P. Tang, J. R. Morante, J. Arbiol, C. Xu, Q. Li
and J. Fransaer, Sens. Actuators B Chem., 2018, 254, 272-
2
81.
4
4
4 Y. Li, F. -M. Li, X. -Y. Meng, S. -N. Li, J. -H. Zeng and Y. Chen,
ACS Catal., 2018, 8, 1913-1920.
5 P. Kannan, T. Maiyalagan, E. Marsili, S. Ghosh, L. Guo, Y.
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Huang, J. A. Rather, D. Thiruppathi, J. Niedziolka-Jönsson and
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DOI: 10.1039/D0TB00094A
M. Jönsson-Niedziolka, Analyst, 2017, 142, 4299-4307.
4
4
4
6 J. Liu, Z. He, S. Y. Khoo and T. T. Y. Tan, Biosens. Bioelectron.,
2
016, 77, 942-949.
7 R. Li, X. Liu, H. Wang, Y. Wu and Z. Lu, Biosens. Bioelectron.,
018, 102, 288-295.
8 Y. Zuo, Y. Liu, J. Li, R. Du, X. Han, T. Zhang, J. Arbiol, N. J.
Divins, J. Llorca, N. Guijarro, K. Sivula and A. Cabot, Chem.
Mater., 2019, 31, 7732-7743.
2
6
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