High-performance supercapacitors and non-enzymatic electrochemical glucose sensor based on tremella-like NiS/CoS/NiCo2S4 hierarchical structure

Article abstract of DOI:10.1016/j.inoche.2019.107581

NiS/CoS/NiCo₂S₄ microflower with hierarchical structure is successfully prepared via facile hydrothermal method. The supercapacitive performance displays that the specific capacitance is up to 513 F g^?1 at a scan rate of 1 mV s^?1. The obvious redox peaks on the cyclic voltammetry curves reveal pseudocapacitive performance of NiS/CoS/NiCo₂S₄. Furthermore, the glucose detection behavior of NiS/CoS/NiCo₂S₄ modified electrode (NiS/CoS/NiCo₂S₄/GCE) has also been performed. Amperometric study indicates that this non-enzymatic sensor displays excellent electrocatalytic performance to glucose. The glucose diffusion from the solution to the electrode surface is the kinetic control process. These results indicate a potential application of NiS/CoS/NiCo₂S₄ for using as an electrode material in supercapacitors and glucose sensor.

Full text of DOI:10.1016/j.inoche.2019.107581

Journal Pre-proof
High-performance
supercapacitors
and
non-enzymatic
electrochemical glucose sensor based on tremella-like NiS/CoS/
NiCo2S4 hierarchical structure
Danqing Li, Xia Zhang, Lei Pei, Chaoyang Dong, Jianguo Shi,
Yuandong Xu
PII:
S1387-7003(19)30742-7
DOI:
https://doi.org/10.1016/j.inoche.2019.107581
INOCHE 107581
Reference:
To appear in:
Inorganic Chemistry Communications
Received date:
Revised date:
Accepted date:
22 July 2019
11 September 2019
12 September 2019
Please cite this article as: D. Li, X. Zhang, L. Pei, et al., High-performance supercapacitors
and non-enzymatic electrochemical glucose sensor based on tremella-like NiS/CoS/
NiCo2S4 hierarchical structure, Inorganic Chemistry Communications (2018),
https://doi.org/10.1016/j.inoche.2019.107581
This is a PDF file of an article that has undergone enhancements after acceptance, such
as the addition of a cover page and metadata, and formatting for readability, but it is
not yet the definitive version of record. This version will undergo additional copyediting,
typesetting and review before it is published in its final form, but we are providing this
version to give early visibility of the article. Please note that, during the production
process, errors may be discovered which could affect the content, and all legal disclaimers
that apply to the journal pertain.
©
2018 Published by Elsevier.

Journal Pre-proof
High-performance supercapacitors and non-enzymatic electrochemical glucose sensor based on
tremella-like NiS/CoS/NiCo S hierarchical structure
2
4
Danqing Li, Xia Zhang*, Lei Pei, Chaoyang Dong, Jianguo Shi, Yuandong Xu*
School of Chemistry and Chemical Engineering, Henan University of Technology, Zhengzhou 450001,
PR China
Abstract
NiS/CoS/NiCo S microflower with hierarchical structure is successfully prepared via facile
2
4
hydrothermal method. The supercapacitive performance displays that the specific capacitance is up to
-1
-1
5
13 F g at a scan rate of 1 mV s . The obvious redox peaks on the cyclic voltammetry curves reveal
pseudocapacitive performance of NiS/CoS/NiCo S . Furthermore, the glucose detection behavior of
2
4
NiS/CoS/NiCo2S4 modified electrode (NiS/CoS/NiCo S /GCE) has also been performed.
2
4
Amperometric study indicates that this non-enzymatic sensor displays excellent electrocatalytic
performance to glucose. The glucose diffusion from the solution to the electrode surface is the kinetic
control process. These results indicate a potential application of NiS/CoS/NiCo S for using as an
2
4
electrode material in supercapacitors and glucose sensor.
Keywords: Composite materials, Hierarchical structure, Energy storage and conversion, Sensors
. Introduction
Recently, transition metal sulfides are extensively investigated as electrodes due to its
1
advantageous electrochemical properties. Among them, nickel and cobalt sulfides are promising
electrode materials in supercapacitors because of its natural abundance and high theoretical specific
capacitance [1–3]. Furthermore, they are also superior materials in electrochemical sensor field [4–6].
Due to the advantageous electrocatalytic oxidation to glucose, nickel and cobalt sulfides are potential
material on non-enzymatic glucose sensor. In particular, the existed studies have displayed that binary
transition metal sulfides have excellent conductivity compared to corresponding transition metal
oxides, ascribing to the smaller band gap [7,8]. Moreover, compared with oxide, the electronegativity
of S atom is lower than that of O atom, so that it can prevent structure decomposition caused by
elongation between layers [7,9]. Therefore, S atom facilitates the electron transformation so that the
electrochemical property of NiS/CoS/NiCo S has been improved. However, the application of
2
4
1

Journal Pre-proof
NiS/CoS/NiCo S in non-enzymatic glucose sensor is scarce. For example, Kannan group produces
2
4
non-enzymatic glucose sensor based on the electrochemical deposition of NiCo S on patterned
2
4
platinum electrode [10]. Chen et al. prepare a novel ball-in-ball hollow NiCo S sphere to detect
2
4
glucose [11]. The existing reports imply that the structure and morphology have great influence on the
electrochemical performance. The hierarchical structure with subunit not only can provide high
specific area but also can shorten the transmission path. Here in this work, the tremella-like
NiS/CoS/NiCo2S4 hierarchical structure with nanosheet subunit has been synthesized. The
supercapacitive performance and the electrochemical sensing property used as nonenzymatic glucose
sensor have been studied.
2. Experimental section
2.1. Materials synthesis
5
mmol NiCl ·6H O, 10 mmol CoCl ·6H O and 10 mmol thioacetamide were dissolved in 30 ml
2 2 2 2
absolute ethanol. After being stirred for 10 min, the mixed solution was transferred to Teflon-lined
°
autoclave and maintained at 120 C for 12 h. After cooling naturally, the resulting precipitate was
°
filtered and washed with distilled water and absolute ethanol. Finally, the sample was dried at 80 C.
2.2. Materials characterization
The obtained NiS/CoS/NiCo S was characterized by X-ray powder diffraction (XRD) on Rigaku
2
4
D/Max-3B diffractometer. The microstructure was studied by transmission electron microscopy (TEM,
JEM JEOL 2100) and field emission scanning electron microscopy (FESEM, JSM-6701F).
2.3. Electrochemical measurements
Electrochemical tests were carried out on CHI660E (Chenhua, Shanghai, China) electrochemical
working station. The working electrode of supercapacitor was fabricated by mixing the electroactive
material, carbon black and poly(tetrafluoroethylene) at a weight ratio of 75:15:10 to form a
homogeneous slurry which was coated onto the nickel foam current collector. A platinum sheet and
Hg/HgO were used as the counter and reference electrodes, respectively. The electrolyte is 2 M KOH
aqueous solution. In glucose detection, Ag/AgCl, platinum wire and glass carbon electrode (GCE)
were used as reference, auxiliary and working electrode, respectively.
3. Results and discussion
2

Journal Pre-proof
The crystal structure of the as-prepared NiS/CoS/NiCo S microflower is shown in Fig. 1a. The
2
4
diffraction peaks located at 30.4°, 34.8° and 45.7° are indexed to the (100), (101) and (102) crystal
planes of NiS (JCPDS card No. 02–1280) [12]. The diffraction peaks at 30.8°, 35.4°, 46.9° and 54.1°
are assigned to the (100), (101), (102) and (110) planes of CoS (JCPDS card No. 65–3418) [13]. And
the peaks at 31.6° and 55.2° correspond to the (311) and (440) planes of NiCo S (JCPDS card No.
2
4
4
3–1477) [14]. Fig. 1b and c displays typical FESEM and TEM images of NiS/CoS/NiCo S . As
2 4
shown in Fig. 1b, it exhibits uniform flower-like microsphere with the diameter of approximate 1 μm.
Furthermore, the NiS/CoS/NiCo S microspheres are all composed of a large amount of sheet-like
2
4
subunits, presenting a hierarchical structure. This can also be supported by TEM image. It is clearly
seen that the nanosheet subunit is very thin and the thickness is around 50 nm. This hierarchical
structure is beneficial for the contact of active material with electrolyte ions and further enhances the
electrochemical performance of NiS/CoS/NiCo S .
2
4
Fig. 1 (a), (b) and (c) are the XRD pattern, FESEM and TEM image of NiS/CoS/NiCo S ,
2
4
respectively.
3

Journal Pre-proof
Fig. 2 (a) and (b) are CV curves and the specific capacitances of NiS/CoS/NiCo S at different scan
2
4
rates, (c) and (d) are the Nyquist plot and the Bode phase plot of NiS/CoS/NiCo S microflower (The
2
4
inset is the equivalent circuit and the enlarged area.), (e) The cycling performance of
-1
NiS/CoS/NiCo S at a scan rate of 5 mV s .
2
4
In order to investigate the supercapacitor performance of NiS/CoS/NiCo S microflowers, the
2
4
cyclic voltammetry (CV) tests carried out at different scan rates are shown in Fig. 2a. The CV curves
-1
exhibit obvious redox peaks at the lower scan rates (< 5 mV s ) and elliptical shape at higher scan
-1
rates (> 20 mV s ), indicating the presence of pseudocapacitive effect and the curves distortion as the
scan rate increases. The reaction mechanism of NiS/CoS/NiCo S in KOH solution is as follows:
2
4
-
-
NiS + OH ↔ NiSOH + e
(1)
4

Journal Pre-proof
-
-
CoS + OH ↔ CoSOH + e
(2)
-
-
CoSOH + OH ↔ CoSO + H O + e (3)
2
The specific capacitance at different scan rates for NiS/CoS/NiCo S is presented in Fig. 2b. It is
2
4
obvious that the values decrease with the increase of scan rates. In order to further explain the charge
transfer performance of NiS/CoS/NiCo S , EIS measurements at a frequency range of 0.01 Hz~100
2
4
kHz is performed. The Nyquist and Bode phase plots are showed in Fig. 2c and d. The straight line in
the typical Nyquist plot is the diffusive resistance of the electrolyte ions into the interior of
NiS/CoS/NiCo S microflowers. The two semicircles confirm the existence of two interfacial
2
4
resistances which can be also reflected from the equivalent circuit (shown in the inset of Fig. 2c). The
high frequency semicircle (shown in the inset) corresponds to the surface states of NiS/CoS/NiCo2S4
and the middle frequency semicircle attributes to the charge transfer resistance at the
electrode/electrolyte interface [15–17]. This phenomenon can also be observed from the Bode phase
4
plot. There are two peaks at high frequency and low frequency, respectively. The peak around 10 Hz
corresponds to the semicircle at high frequency. Another peak around 1 Hz reflects the diffusion of
electrolyte ion in the electrode solid. The cycle stability of NiS/CoS/NiCo S is exhibited in Fig. 3e. At
2
4
-1
a scan rate of 5 mV s , it presents a good cycling behavior during 500 cycles and the specific
-1
capacitance is around 300 F g , suggesting the excellent reversibility and stability of
NiS/CoS/NiCo S .
2
4
The sensing behavior of NiS/CoS/NiCo S has also been investigated to detect glucose in NaOH
2
4
electrolyte. Fig. 3a displays the CV curves of bare GCE (BGCE) and NiS/CoS/NiCo S /GCE. It is
2
4
clear that BGCE shows no obvious redox peaks in the given potential window of 0~0.8 V, whereas
NiS/CoS/NiCo S /GCE exhibits oxidation and reduction peaks around 0.6 V and 0.45 V, respectively.
2
4
Moreover, the anodic (I ) and cathodic (I ) peak current increase distinctly in the presence of glucose,
pa
pc
indicating that NiS/CoS/NiCo S /GCE exhibits prominent electrocatalytic activity toward glucose
2
4
oxidation. The CV curves of NiS/CoS/NiCo S /GCE at different scan rates are shown in Fig. 3b. It is
2
4
clear that the anodic peak (I ) shifts positively while the cathodic peak (I ) moves negatively with the
pa
pc
increase of scan rate. As displayed in Fig. 3c, the peak current (I ) response is linearly related to the
p
1/2
square root of scan rate (v ), manifesting that the glucose oxidation on NiS/CoS/NiCo S /GCE is
2
4
5

Journal Pre-proof
controlled by diffusion process [18]. That is to say, the overall reaction rate of the glucose
electrocatalytic oxidation is controlled by the diffusion of glucose molecules from the bulk liquid to
the surface active sites of NiS/CoS/NiCo S electrode.
2
4
Fig. 3 (a) CV curves of GCE and NiS/CoS/NiCo S /GCE with or without glucose in 0.1 M NaOH at
2
4
-1
the scan rate of 50 mV s , (b) CV curves of NiS/CoS/NiCo S /GCE in 0.1 M NaOH blank solution at
2
4
-1
different scan rates (1~200 mV s ), (c) Anodic and cathodic peak current vs. square root of scan rate
1
/2
(
v ), (d) Nyquist plots and (e) Phase angle Bode plots for BGCE and NiS/CoS/NiCo S /GCE, (f) The
2 4
-1/2
Zr–ω curves in the low frequency region.
6

Journal Pre-proof
To further explore the charge transfer property of NiS/CoS/NiCo S , EIS measurement is
2
4
performed. Fig. 3d displays the Nyquist plots of BGCE and NiS/CoS/NiCo S /GCE in 5 mM
2
4
3
-/4-
[
Fe(CN)6]
with 0.1 M KCl as the supporting electrolyte. The semicircle at the high frequency
region can be explained as the charge-transfer resistance (R ) corresponding to the diffusion of the
ct
electrolyte ions into the electrode through electrode/electrolyte interface [19]. The straight line
corresponds to the Warburg impedance, attributing to the solid-state diffusive resistance of electrolyte
ions into the interior bulk electrode. It is obvious that the radius of the semicircle for
NiS/CoS/NiCo S /GCE is smaller than that of BGCE, suggesting the fast charge transfer speed of
2
4
NiS/CoS/NiCo S /GCE. This result can also be supported by the Bode phase plot. As revealed in Fig.
2
4
3
e, it is clear that the peaks corresponding to the semicircles of BGCE and NiS/CoS/NiCo S /GCE has
2 4
3
shifted. The peaks around the frequency range of 10 Hz for BGCE and NiS/CoS/NiCo S /GCE are all
2
4
-1/2
attributed to the bulk electron transfer resistance [20]. Last but not the least, the Z −ω (angular
r
frequency ω=2πf) curves in the low frequency region (below 1.0 Hz) is displayed in Fig. 3f.
Apparently, the slope of NiS/CoS/NiCo S /GCE is slightly larger than that of BGCE, that is to say, the
2
4
diffusion resistance of the glucose into the NiS/CoS/NiCo S body is high. This may be caused by the
2
4
space structure of glucose.
. Conclusions
In a word, NiS/CoS/NiCo S hierarchical structure is fabricated by hydrothermal method. The
4
2
4
supercapacitive and glucose sensing performance have been investigated. It reveals high specific
capacitance and excellent glucose sensing behavior. The redox reaction of glucose on the
NiS/CoS/NiCo S is controlled by the diffusion process of glucose from the solution to the electrode
2
4
surface. These results maybe lay the foundation for the nickel and cobalt based electrode materials.
Acknowledgement
This work is financially supported by the Youth Backbone Teacher Project of Henan University
of Technology (No.2015007) and the Institutions of Higher Learning Key Scientific Research Project
(
No.19B150005).
References
7

Journal Pre-proof
[
[
1] F.Y. Zhou, Q.L. Liu, J.J. Gu, W. Zhang, D. Zhang, J. Power Sources 273 (2015) 945.
2] X.B. Xu, W. Zhong, X. Zhang, J. Dou, Z.G. Xiong, Y. Sun, T.T. Wang, Y.W. Du, J. Colloid Interf.
Sci. 543 (2019) 147.
[
[
[
3] S. Rafai, C. Qiao, M. Naveed, Z.T. Wang, W. Younas, S. Khalid, C.B. Cao, Chem. Eng. J. 362
(
2019) 576.
4] W. Abbas, N. Akhtar, Q.L. Liu, T.F. Li, I. Zada, L.L. Yao, R. Naz, W. Zhang, M. Ehsan Mazhar, D.
Zhang, D.L. Ma, J.J. Gu, Sens. Actuators B 282 (2019) 617.
5] H. Mao, Z.Q. Cao, X. Guo, D.Y. Sun, D.L. Liu, S.Y. Wu, Y. Zhang, X.M. Song, ACS Appl. Mater.
Interfaces 11 (2019) 10153.
[
[
[
6] V. Sridhara, H. Park, J. Alloy. Compd. 764 (2018) 490.
7] Z.Y. Yang, X.H. Zheng, J.B. Zheng, Sens. Actuators B 253 (2017) 34.
8] L.F. Shen, L. Yu, H.B. Wu, X.Y. Yu, X.G. Zhang, X.W. (David) Lou, Nat. Commun. 6 (2015)
6694.
[
9] R. Naz, M. Imtiaz, Q.L. Liu, L.L. Yao, W. Abbas, T.F. Li, I. Zada, Y. Yuan, W.S. Chen, J.J. Gu,
Carbon 152 (2019) 697.
[
[
[
[
[
[
10] P.K. Kannan, C.X. Hu, H. Morgan, C.S. Rout, Chem. Asian J. 11 (2016) 1837.
11] D.L. Chen, H.Y. Wang, M.H. Yang, Anal. Methods 9 (2017) 4718.
12] M. Lu, N. Gao, X.J. Zhang, G.S. Wang, RSC Adv. 9 (2019) 5550.
13] C.Q. Feng, Y.R. Li, M. Wang, G.Y. Zhao, Z.S. Wang, Electrochim. Acta 301 (2019) 220.
14] C.Q. Duan, Y.H. Dong, Q.L. Sheng, J.B. Zheng, Talanta 198 (2019) 23.
15] A. Somdee, J. Alloy. Compd. 777 (2019) 1251.
8

Journal Pre-proof
[
16] N. Wang, Q.L. Liu, D.M. Kang, J.J. Gu, W. Zhang, D. Zhang, ACS Appl. Mater. Interfaces 8
(
2016) 16035.
[
[
17] F.Y. Zhou, Q.L. Liu, J.J. Gu, W. Zhang, D. Zhang, Electrochim. Acta 170 (2015) 328.
18] M. Rezaeinasab, A. Benvidi, M.D. Tezerjani, S. Jahanbani, A.H. Kianfar, M. Sedighipoor,
Electroanal. 29 (2017) 423.
[
[
19] K. Liu, J.L. Cui, J.P. Yin, J.Z. Man, Y.F. Cui, Z.S. Wen, J.C. Sun, J. Alloy. Compd. 765 (2018)
229.
20] J. Liu, Q. Zhang, T. Zhang, J.T. Li, L. Huang, S.G. Sun, Adv. Funct. Mater. 25 (2015) 3599.
9

Journal Pre-proof
Conflict of interest statement
The authors declare that we have no financial and personal relationships with other
people or organizations that can inappropriately influence this work.
Signature: Yuandong Xu (Corresponding Author)
Date: Sep. 11, 2019
1
0

Journal Pre-proof
Graphical Abstract
11

Journal Pre-proof
Highlights



NiS/CoS/NiCo S microflower is prepared via hydrothermal method.
2
4
NiS/CoS/NiCo S displays favorable pseudocapacitive and glucose sensing behavior.
2
4
The redox reaction of glucose on NiS/CoS/NiCo S is controlled by the diffusion process.
2
4
1
2