"Arch-shaped" NiO Modified Electrode for Enzyme-free Glucose Detection and Its Preparation Method

Abstract

The present invention discloses an "arch-shaped" NiO modified electrode for enzyme-free glucose detection and its manufacturing method. The "arch-shaped" NiO modified electrode has the following physical and chemical properties: the NiO particles are evenly distributed on the carbon paper, presenting an "arch-shaped" structure. The middle of the "arch-shaped" structure has a pore structure, and the surface is rough with a layered stacking structure. The "arch-shaped" structure contains C, O, and Ni elements. By synthesizing "arch-shaped" NiO on the carbon paper, its specific surface area is increased, its active sites are increased, thereby improving its electrocatalytic oxidation performance. In addition, by constructing an "arch-shaped" NiO / carbon paper self-supporting electrode, it helps to improve the conductivity of the electrode, and the carbon fiber provides space for the growth of nanomaterials, which helps to improve its dispersibility, thereby contributing to improving its electrocatalytic oxidation performance.

Description

Technical Field

[0001] The present invention relates to the technical field of glucose detection, and particularly to an "arch-shaped" NiO modified electrode for enzyme-free glucose detection and a preparation method thereof. Background Art

[0002] At present, there are many methods for measuring glucose content. However, electrochemical sensor detection has attracted much attention due to its advantages such as low cost, convenience and rapidity, and high sensitivity and rapid response. Among them, nanostructured NiO is considered to be one of the most promising glucose catalytic materials because of its good electrocatalytic activity, low cost, good stability and chlorine poisoning resistance. Subash et al. synthesized NiO in GO by an ultrasonic-assisted method and studied its response to glucose in an alkaline medium. The linear range and detection limit were 0.62 mμM - 2.2 mM and 0.17 μM, respectively (Subash Vetri Selvi, Alagumalai Krishnapandi, Shen Ming Chen, Shanmugam Ragurethinam, Huang JiShiuan. New Journal of Chemistry, 2020, 44(35):15071 - 15080). Venkadesh et al. [7] prepared ultra-small NiO nanoparticles by complexing nickel with p-phenylenediamine and used them to modify a glassy carbon electrode to construct a non-enzymatic glucose sensor. The sensitivity of this sensor was 0.310 μA·μM-1·cm-2, the detection limit was 3.5 μM, and the response time was less than 5 s (Venkadesh A, Mathiyarasu J., Dave S., Radhakrishnan S.. Inorganic Chemistry Communications, 2021, 131:108779.). Ni et al. synthesized activated carbon / NiO by combining chemical activation and hydrothermal methods and used it to modify a glassy carbon electrode to construct a glucose sensor with a linear range of 10 μM - 3.3 mM and a detection limit of 1 μM (Yue Ni, Jian Xu, Qing Liang, Shijun Shao. Sensors & Actuators: B. Chemical, 2017, 250:491 - 498.). Mishra et al. grew petal-shaped NiO on an FTO substrate. The sensitivity and detection limit of the constructed non-enzymatic sensor were 3.9 μA·μM-1·cm-2 and 1 μM, respectively, and it had good stability, repeatability and anti-interference ability (Mishra Suryakant, Yogi Priyanka, Sagdeo P R, Kumar Rajesh. Nanoscale research letters, 2018, 13(1):16.).Anweshi et al. synthesized multi-shell NiO hollow spheres using the sacrificial template method. The constructed sensor has a linear range of 2 - 2.6 mM and a high sensitivity of 1646 μA·μM-1·cm-2 (Anweshi Dewan, Sattwick Haldar, and Remya Narayanan. Journal of Solid State Electrochemistry, 2020, 25(3): 1 - 10. DOI: 10.1007 / s10008-020-04861-2.). Although various nanostructured NiO has been used to construct enzyme-free glucose sensors, the nanostructured NiO is prone to aggregation, reducing its specific surface area and thus its electrocatalytic oxidation performance. Summary of the Invention

[0003] (I) Technical Problem

[0004] The present invention mainly solves the problem that nanostructured NiO is prone to aggregation and reduces its specific surface area. For this purpose, the present application provides a preparation method of an "arch-shaped" NiO modified electrode for enzyme-free glucose detection.

[0005] (II) Technical Solution

[0006] In order to improve the conductivity of the electrode, reduce the aggregation of nanomaterials, and reduce the steps of preparing the electrode, the present invention constructs a self-supporting electrode on hydrophilic carbon paper to construct an enzyme-free glucose sensor. This sensor has a wide detection range, high sensitivity, good reproducibility and stability, as well as excellent anti-interference ability and actual measurement effect.

[0007] The present invention provides a preparation method of an "arch-shaped" NiO modified electrode for enzyme-free glucose detection. The method synthesizes a special-shaped electrode material by potentiostatic method, and is characterized by the following steps:

[0008] S1. Pretreatment of carbon paper: Cut the carbon paper into strips of 1 cm × 2 cm, ultrasonically clean it 2 - 3 times with absolute ethanol and distilled water respectively, and put it in an oven at 60 °C for drying for later use;

[0009] S2. Preparation of electrolyte: Prepare a nickel sulfate solution with a concentration of 0.1 mol / L as the electrolyte;

[0010] S3. Preparation of the electrode: Use the pretreated carbon paper as the working electrode, a platinum sheet electrode as the auxiliary electrode, and a calomel electrode as the reference electrode to form a three-electrode system; Add 20 ml of nickel sulfate electrolyte to a beaker, select the amperometric current-time program on an electrochemical workstation of model CHI660D, set the working potential and time to -0.85 V and 240 seconds respectively. After the operation is completed, remove the electrode, wash it with distilled water, and dry it under an infrared lamp to obtain the "arch-shaped" NiO modified electrode.

[0011] By synthesizing "arch-shaped" NiO on the carbon paper, its specific surface area is increased, its active sites are increased, and thus its electrocatalytic oxidation performance is improved.

[0012] On the other hand, the present invention obtains an "arch-shaped" NiO modified electrode, which is characterized in that the "arch-shaped" NiO modified electrode has the following physical and chemical properties: the NiO particles are evenly distributed on the carbon paper, presenting an "arch-shaped" structure. The "arch-shaped" structure is like an arch spanning the carbon fibers, with a hole structure in the middle and a rough surface with a layered stacking structure, like the steps on an arch; the special "arch-shaped" structure contains C, O, and Ni elements. This electrode has a wide detection range (0 - 12.21 mmol / L), a high sensitivity (357.47 μA·mM -1 ·cm -2 ), good reproducibility and stability, as well as excellent anti-interference ability and actual measurement effect.

[0013] (III) Beneficial effects

[0014] In view of the fact that the electrocatalytic oxidation performance of nanomaterials is easily affected by their morphology, the present invention uses the potentiostatic method to synthesize electrode materials with special morphologies. By synthesizing "arch-shaped" NiO on the carbon paper, its specific surface area is increased, its active sites are increased, and thus its electrocatalytic oxidation performance is improved. In addition, by constructing an "arch-shaped" NiO / carbon paper self-supporting electrode, it helps to improve the electrical conductivity of the electrode, and the carbon fibers provide space for the growth of nanomaterials, which helps to improve their dispersion, and thus helps to improve their electrocatalytic oxidation performance.

[0015] In addition, this electrode has a wide detection range (0 - 12.21 mmol / L), a high sensitivity (357.47 μA·mM -1 ·cm -2 ), good reproducibility and stability, as well as excellent anti-interference ability and actual measurement effect. Description of the drawings

[0016] Figure 1 SEM and EDS diagrams of the NiO / carbon paper electrode.

[0017] Figure 2 The i-t curve (a) of the "arch-shaped" NiO / carbon paper electrode and the linear fitting graph (b) of its current intensity versus glucose concentration.

[0018] Figure 3 Reproducibility (a), stability (b) and anti-interference ability (c) of the "arch-shaped" NiO / carbon paper electrode.

[0019] Figure 4 Measured effect of the "arch-shaped" NiO / carbon paper electrode on 5% glucose injection. Specific implementation manners

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] Please refer to Figures 1-4 As shown, the present invention provides a preparation method of "arch-shaped" NiO nanomaterials: using the pretreated carbon paper as the working electrode, a platinum sheet electrode as the auxiliary electrode, and a calomel electrode as the reference electrode to form a three-electrode system. Add 20 ml of nickel sulfate electrolyte to a beaker, select the amperometric current-time program in the electrochemical workstation of model CHI660D, set the working potential and time to -0.85 V and 240 seconds respectively. After the operation is completed, remove the electrode, wash it with distilled water, and dry it under an infrared lamp. The morphology of the prepared NiO is shown in Figure 1 . It can be seen from the figure that NiO particles are evenly distributed on the carbon paper, presenting a special "arch-shaped" structure, like an arch spanning the carbon fiber, with a hole structure in the middle and a rough surface with a layered stacking structure, similar to the steps on an arch. The special structure increases the specific surface area of the electrode, improves the number of accessible active sites, and enables sufficient contact with glucose. And this electrode contains C, O and Ni elements. Therefore, the prepared NiO / CP electrode has a good catalytic oxidation effect.

[0022] Under the condition that the detection potential is 0.50 V, the amperometric current-time method is used to test the current value by continuously adding a certain concentration of glucose (a total of 15 times, the lowest concentration is 0.5 μmol / L, and the highest concentration is 12.21 mmol / L) to the continuously contained 0.1 mol / L NaOH solution. According to the concentration of glucose and the current response intensity, fitting analysis is carried out, as shown in Figure 2。The current intensity and glucose concentration show a good linear relationship within a certain range, as shown in Table 1, which indicates that the NiO / carbon paper electrode has good sensitivity and a wide detection range.

[0023]

[0024] Table 1: Electrode performance of the "arch-shaped" NiO / carbon paper enzyme-free glucose sensor

[0025] In addition, the reproducibility, stability and anti-interference ability of the electrode were investigated, as shown in Figure 3 , and the actual measurement effect on 5% glucose injection solution is shown in Figure 4 , which indicates that the electrode has good reproducibility and stability, as well as excellent anti-interference ability and actual measurement effect.

[0026] By using the standard addition method to test the glucose content in the actual sample, the sample solution is 5% glucose injection solution. 20 μL of the glucose injection solution to be measured (concentration: 5%) and 20 μL of 0.1 mol / L glucose standard solution were successively added, and the i-t was used to test the results, and the current and concentration were linearly fitted. The results are shown in Figure 3 , the linear relationship between the current and glucose concentration is y = 0.64906x + 0.17389, and the fitting constant R2 is 0.9937. It can be calculated that the concentration of the glucose injection solution is 0.267 mmol / L, which is not much different from the theoretical concentration (0.278 mmol / L) of the 5% glucose injection. The spiked recovery rate is 96.04%. After three actual measurements, the RSD is 3.93%, indicating that the "arch-shaped" NiO / CP electrode can be used to determine the glucose concentration in actual samples.

[0027] It should be noted that in this article, terms such as "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method, article or device. Without further limitations, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0028] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Preparation method of "arch-shaped" NiO modified electrode for enzyme-free glucose detection, characterized in that, It includes the following steps: S1. Pretreatment of carbon paper: Cut the carbon paper into strips of 1 cm × 2 cm, ultrasonically clean it with absolute ethanol and distilled water for 2 - 3 times respectively, and put it in an oven to dry at 60 °C for later use; S2. Preparation of electrolyte: Prepare a nickel sulfate solution with a concentration of 0.1 mol / L as the electrolyte; S3. Preparation of electrode: Use the pretreated carbon paper as the working electrode, a platinum sheet electrode as the auxiliary electrode, and a calomel electrode as the reference electrode to form a three - electrode system; Add 20 ml of nickel sulfate electrolyte to a beaker, select the amperometric current - time program in the electrochemical workstation of model CHI660D, set the working potential and time to - 0.85 V and 240 seconds respectively. After the operation is completed, remove the electrode, wash it with distilled water, and dry it under an infrared lamp to obtain the "arch - shaped" NiO modified electrode.

2. An "arch-shaped" NiO modified electrode fabricated by using the preparation method according to claim 1, characterized in that, The "arch - shaped" NiO modified electrode has the following physical and chemical properties: The NiO particles are evenly distributed on the carbon paper, presenting an "arch - shaped" structure. There is a pore structure in the middle of the "arch - shaped" structure, and the surface is rough with a layered stacking structure; The "arch - shaped" structure contains C, O, and Ni elements.

3. The "arch-shaped" NiO modified electrode according to claim 2, characterized in that, The detection range of this electrode is 0 - 12.21 mmol / L, and the sensitivity is 357.47 μA·mM -1 ·cm -2 .

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