CN111239217A - N-doped carbon-wrapped Co @ Co3O4Core-shell particle polyhedron and preparation method and application thereof - Google Patents

Abstract

The invention discloses a N-doped carbon-wrapped Co@Co ₃ O ₄ core-shell particle polyhedron (Co@Co ₃ O ₄ ‑NC) and a preparation method and application thereof. The preparation method of the Co@Co ₃ O ₄ -NC comprises the following steps: 1) carbonizing the ZIF-67 crystal in an inert atmosphere, and naturally cooling to room temperature to obtain a Co-NC composite material; 2) carbonizing the Co-NC The NC composites were obtained by heat treatment in air at 220°C for 24h at a heating rate of 2°C min ^-1 . Benefiting from the special structure and nitrogen doping of Co@Co ₃ O ₄ ‑NC, Co@Co ₃ O ₄ ‑NC exhibits high performance for non-enzymatic electrochemical glucose sensing. The sensitivity of the sensor fabricated with Co@Co ₃ O ₄ ‑NC can reach 251.9 μAmM ^‑1 cm ^‑2 , the detection limit can be as low as 0.3 μM (S/N=3), and the linear range is 0.01‑4 mM. Sensing electrodes are also feasible in practical sample analysis.

Description

N-doped carbon-encapsulated Co@Co3O4 core-shell particle polyhedron and preparation method thereof application

technical field

The invention belongs to the field of materials, and in particular relates to an N-doped carbon-wrapped Co@Co ₃ O ₄ core-shell particle polyhedron and a preparation method and application thereof.

Background technique

In clinical research, bioprocessing, and food industry, the development of reliable, cost-effective and high-performance sensing devices is considered an important scientific and technological means for accurate and rapid glucose detection. In terms of detection technology, electrochemical technology has received extensive attention due to its uniqueness, simplicity, sensitivity, fast response time, low detection limit, long-term stability and rapid detection. Electrochemical glucose sensors are mainly divided into enzyme-based sensing and non-enzymatic glucose sensing. However, enzymatic sensors always rely on catalytic enzymes, such as glucose oxidase. Under its catalysis, glucose is oxidized by oxygen to gluconolactone and H ₂ O ₂ . The produced hydrogen peroxide is reduced by the mediator, causing a small change in the current response. Moreover, due to its instability, high cost, and difficulty in immobilizing enzymatic sensors, many studies have paid more attention to the development of non-enzymatically active agents for electrochemical glucose sensors.

Recently, composites with _{Co3O4 -} based nanoparticles (NPs) of different structures and sizes have attracted worldwide attention due to their high earth content, environmental friendliness, and cost-effectiveness. However, the electrical conductivity _of Co3O4 NPs is unfavorable for non _- enzymatic detection of glucose. The preparation of composite structures of Co ₃ O ₄ NPs and conductive carbon materials is a general method to improve the electrical conductivity of electrode materials. Such as _{Co3O4 NPs} and graphene composites, _{Co3O4 NPs} and carbon nanotube composites and other porous carbon materials. However, the composites of Co ₃ O ₄ NPs and conductive carbon materials usually suffer from problems such as aggregation and decreased activity. To date, metal-organic frameworks (MOFs) are well-defined hollow materials synthesized from the self-assembly of metal ions and organic molecules. And, since MOFs have high surface areas and porous mass transfer pathways, they are excellent sacrificial templates for the fabrication of porous carbon-supported metals or metal oxides to exhibit potential catalytic activity. Furthermore, small-sized metal or metal oxide particles can be embedded in the carbon framework in situ without agglomeration. Therefore, MOF-derived nanocomposites have recently been investigated as efficient catalysts.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an N-doped carbon wrapped Co@Co ₃ O ₄ core-shell particle polyhedron.

The N-doped carbon-wrapped Co@Co ₃ O ₄ core-shell particle polyhedron (Co@Co ₃ O ₄ -NC) provided by the present invention is prepared by a method comprising the following steps:

1) carbonizing the ZIF-67 crystal (Zeolitic Imidazolate Framework-67, Zeolitic Imidazolate Framework-67) in an inert atmosphere, and naturally cooling to room temperature to obtain a Co-NC composite;

2) The Co-NC composite was heated to 220±20°C in air, and kept at 200±1°C for 24±5 h to form Co@Co ₃ O ₄ -NC.

In step 1) of the above method, the inert atmosphere can be nitrogen, the carbonization temperature is 800±50°C (specifically 800°C), and the time is 1-3h (specifically 2h). The heating rate from room temperature to the carbonization temperature may be 1 to 5°C min ^-1 (specifically, 5°C min ^-1 ).

In the above-mentioned method step 1), the ZIF-67 crystal is prepared according to the following method: the cobalt nitrate and 2-MeIM (2-methylimidazole) are reacted in an ethanol solution, and the precipitate is collected by centrifugation after the reaction is finished; The precipitate is washed with ethanol and then dried.

Among them, the mass ratio of cobalt nitrate and 2-MeIM was 0.727:1.64. Specifically, the reaction was stirred at room temperature for 2 hours. The drying is specifically drying in a vacuum oven at 80°C overnight.

The heating rate in step 2) of the above method is 2±1°C min ⁻¹ .

According to an embodiment of the present invention, step 2) of the above method may specifically be: heating the Co-NC composite material to 220° C. in air, and keeping the temperature at 200° C. for 24 hours to form Co@Co ₃ O ₄ -NC.

Another object of the present invention is to provide the application of the above N-doped carbon wrapped Co@Co ₃ O ₄ core-shell particle polyhedron (Co @Co ₃ O ₄ -NC).

The application provided by the present invention is the application of Co@Co ₃ O ₄ -NC in the preparation of a non-enzymatic electrochemical glucose sensor.

Another object of the present invention is to provide a non-enzymatic electrochemical glucose sensor.

The non-enzymatic electrochemical glucose sensor provided by the present invention includes a working electrode, a counter electrode and a reference electrode, wherein the working electrode is a base electrode whose surface is modified with a Co@Co ₃ O ₄ -NC layer.

Specifically, the base electrode may be a glassy carbon electrode (GCE). The amount of Co@Co ₃ O ₄ -NC in the working electrode relative to the base electrode may be 0.357 mg·cm ^-2 .

The preparation methods of Co-NC/GCE and Co ₃ O ₄ -NC/GCE in the present invention are the same as above.

Specifically, the counter electrode may be a platinum electrode.

Specifically, the reference electrode can be Hg/HgO.

The present invention also protects a method for detecting glucose.

The method includes the following steps: using the above-mentioned non-enzymatic electrochemical glucose sensor to electrochemically detect a solution containing glucose.

The working voltage of the non-enzymatic electrochemical glucose sensor is 0.64V (the reference electrode is Hg/HgO).

The concentration of glucose in the glucose-containing solution may be 0.01-4 mM.

The glucose-containing solution contained 0.1 M KOH or NaOH.

The glucose-containing solution also contains dopamine (DA) and/or uric acid (UA) and/or ascorbic acid (AA).

The inventors of the present invention prepared Co@Co ₃ O ₄ core-shell particle-encapsulated N-doped carbon polyhedra (Co@Co ₃ O ₄ -NC) by a simple pyrolysis method. Benefiting from the special structure and nitrogen doping, Co@Co3O4 _- NCs exhibit high performance for non _- enzymatic electrochemical glucose sensing. The sensitivity of the sensor fabricated with Co@Co ₃ O ₄ -NC can reach 251.9 μA mM ^-1 cm ^-2 , the detection limit can be as low as 0.3 μM (S/N=3), and the linear range is 0.01-4 mM. Sensing electrodes are also feasible in practical sample analysis.

Description of drawings

Figure 1 shows the XRD patterns of (a) Co-NC, Co ₃ O ₄ -NC and Co@Co ₃ O ₄ -NC; (b) Co-NC, Co ₃ O ₄ -NC and Co@Co ₃ O ₄ - Raman spectrum of NC; (c) nitrogen adsorption-desorption isotherm of Co@Co ₃ O ₄ -NC; (d) XPS spectrum of Co@Co ₃ O ₄ -NC; (e) Co@Co ₃ O ₄ - High-resolution Co 2p spectrum of NC; (f) High-resolution XPS spectrum of N 1s.

Figure 2 is (a) SEM image of Co-NC; (b) TEM image of Co-NC; (c) HRTEM image of Co-NC; (d) SEM image of Co@Co ₃ O ₄ -NC; (e) ) TEM image of Co@Co3O4 _- NC; (f) HRTEM image _of Co@Co3O4 _- NC; (g) SEM image _of Co3O4 _- NC; (h) _{Co3O4 - NC} TEM image of ; (i) HRTEM image of Co3O4-NC.

Figure 3 is a graph of (a) naked GCE, Co-NC/GCE, Co@Co ₃ O ₄ -NC/GCE and Co ₃ O ₄ -NC/GCE in 0.1 M KOH with or without 5 mM glucose. CV curve. (b) CV curves of bare GCE and Co@Co ₃ O ₄ -NC/GCE in 5 mM K ₃ Fe(CN) ₆ /0.1 M KCl solution.

Figure 4 shows (a) the CV curves of Co@Co ₃ O ₄ /GCE in 0.1 M KOH solution when the scanning speed is 2-200 mV s ^-1 . (b) Peak current density versus scan rate.

Fig. ₅ is the amperometric response of (a) Co@Co3O4/GCE with continuous addition of glucose to 0.1 M KOH at 0.64 V _; (b) the calibration curve of current versus glucose concentration, the error bars represent the three-step measurements performed by different electrodes. Standard deviation of independent measurements; (c) anti-interference test of Co@Co ₃ O ₄ /GCE in 0.1 mM glucose and 0.1 mM KOH solution in the presence of 0.1 mM different interfering substances; (d) Co@Co ₃ O ₄ /GCE Long-term stability of GCE electrodes.

Detailed ways

The present invention will be described below through specific embodiments, but the present invention is not limited thereto, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention. within.

The experimental methods used in the following examples are conventional methods unless otherwise specified.

The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

2-Methylimidazole (2-MeIM, 99%) used in the following examples was purchased from Macklin. Cobalt nitrate hexahydrate (Co(NO ₃ )·6H ₂ O, 98.5%), potassium hydroxide (KOH, ≥85.0%), methanol (CH ₃ OH, ≥99.7%) were purchased from Sinopharm Reagent. Glucose (99%) was purchased from Acros organics. Ascorbic acid (AA, ≥99.0%), uric acid (UA, ≥99.0%) and dopamine (DA) were purchased from Sigma-Aldrich. All other reagents were of analytical grade and were used without further purification. All solutions were prepared with deionized (DI) water.

Example 1. Preparation of N-doped carbon polyhedra (Co@Co ₃ O ₄ -NC) encapsulated by Co@Co ₃ O ₄ core-shell particles

1.1 Preparation of ZIF-67

0.727 g of cobalt nitrate was dissolved in 25 mL of methanol, which was then poured into 25 mL of methanol containing 1.64 g of 2-MeIM (2-methylimidazole). After mixing the solution was stirred at room temperature for 2 hours. The obtained precipitate was collected by centrifugation, washed 3 times with methanol, and dried in a vacuum oven at 80° C. overnight to yield ZIF-67 crystals (Zeolitic Imidazolate Framework-67) in purple color.

1.2 Preparation of Co-NC composites

The ZIF-67 crystals were carbonized at 800 °C for 2 h under N ₂ atmosphere at a heating rate of 5 °C min ^-1 (that is, heated to 800 °C at a rate of 5 °C min ^-1 , and then kept for 2 h), and naturally cooled to room temperature to obtain Co. -NC.

1.3 Preparation of Co@Co3O4 _{- NC} composites

The Co-NC composites were heated to 220 °C at a heating rate of 2 °C min ^-1 in air, and kept at 200 °C for 24 h to form Co@Co ₃ O ₄ -NC.

_1.4 Preparation of Co3O4 _- NC composites

Co-NC composites were heated to 220°C at a heating rate of 2°C min ^-1 in air, and kept at 200°C for 48 h to form Co@Co ₃ O ₄ -NC.

1.5 Characterization and Test Methods

在PANalytical X’pert Pro X射线衍射仪上进行的。使用AlKαX射线源在ThermoScientific Escalab 250光谱仪上记录X射线光电子能谱(XPS)分析。使用 XploRA拉曼显微镜获得拉曼光谱，激发波长为785nm。BET比表面积是使用 Nova2000E通过在77.35K下的氮吸附确定的。电化学测量是在CHI660E电化学工作站上进行的，该工作站基于由工作电极，铂片对电极以及Hg/HgO参比组成的三电极系统。电解质为0.1M KOH，并在实验前脱氧。The structure and morphology of the catalysts were characterized by field emission scanning electron microscopy (FESEM, JSM-6701) and transmission electron microscopy (TEM, JEOLJEM-2100). X-ray diffraction (XRD) measurements were made using CuKα radiation

Performed on a PANalytical X'pert Pro X-ray diffractometer. X-ray photoelectron spectroscopy (XPS) analyses were recorded on a ThermoScientific Escalab 250 spectrometer using an AlKα X-ray source. Raman spectra were acquired using an XploRA Raman microscope with an excitation wavelength of 785 nm. The BET specific surface area was determined by nitrogen adsorption at 77.35K using Nova2000E. Electrochemical measurements were performed on a CHI660E electrochemical workstation, which is based on a three-electrode system consisting of a working electrode, a platinum sheet counter electrode, and a Hg/HgO reference. The electrolyte was 0.1 M KOH and deoxygenated before the experiments.

2.1 Material Characterization

XRD analysis was performed to confirm the designed structure of Co@Co3O4 _{- NC} (Fig. 1a). Diffraction peaks appear at 44.2° and 51.5°, corresponding to reflections from the (111) and (200) planes of the face-centered (fcc) metallic Co phase (JCPDS No. 15-0806). Meanwhile, another peak appeared at 31.2°, 36.9°, 44.8°, 59.3° and 65.2°, and corresponded to the cubic (220), (311), (400), (511) and (440) reflection tips, respectively Spar Co ₃ O ₄ phase (JCPDS No. 42-1467). _The Co3O4 _- NC samples _were oxidized longer in air and showed stronger diffraction peaks for the cubic spinel Co3O4 _. Whereas the Co-NC samples obtained without further oxidation treatment in air showed only diffraction peaks of metallic Co phase. The Raman spectrum of Co@Co ₃ O ₄ -NC showed the existence of spinel Co ₃ O ₄ structure on the surface, with typical multiple Raman shifts at 482 cm ^-1 , 521 cm ^-1 , 621 cm ^-1 and 692 cm ^-1 , respectively (Fig. 1b). _{The Co3O4 -} NC samples show stronger Raman shift signals for _Co3O4 , which is because the metallic Co nanoparticles are fully oxidized, while the oxidation time in air is longer. The Co-NC samples showed no Raman signal in the tested range.

_The N adsorption _- desorption isotherm curves of Co@Co3O4 _- NCs are shown in Fig. 1c. The pore size was calculated using the BJH method, and as a result, the average pore size was about 5 nm, and the BET surface area and cumulative pore size of Co@Co ₃ O ₄ -NC were 322.807 m ² g ^-1 and 0.279 cm ³ g ^-1 . _The high surface area and pores of Co@Co3O4 _- NCs can increase the effective space for diffusing glucose and electrolytes to the catalyst surface.

The XPS survey spectrum of Co@Co ₃ O ₄ -NC shows that its surface is mainly composed of C (64.2 at%), N (2.9 at%), O (23.6 at%) and Co (9.3 at%) (Fig. 1d) . High-resolution XPS spectra in the Co 2p _3/2 signal region (Fig. 1e) were curve-fitted into a typical metallic Co phase at _778.9 eV and Co3O4 at _780.4 eV. ^29N actually comes from the decomposed organic ligand and provides evidence for successful doping. Due to spin-orbit coupling, the high-resolution N1s spectrum (Fig. 1f) can be deconvoluted into three sub-peaks including pyridine-N (399.5 eV), graphitic-N (401.3 eV) and oxide-N (405.2 eV) .

These results are in good agreement with the designed catalyst structure of partially oxidized Co particles anchored in a nitrogen-doped carbon framework.

The morphologies of the Co@Co ₃ O ₄ -NC catalysts were investigated by SEM and TEM. The SEM image of Co@Co ₃ O ₄ -NC (Fig. 2d) shows a regular dodecahedral morphology with an average particle diameter of about 350 nm, similar to pristine ZIF-67 crystals and Co-NCs (Fig. 2a). However, with the increase of oxidation time, the carbon skeleton appeared to be crushed to different degrees. Especially in Fig. 2g, Co3O4 _{- NCs} show a more disordered structure. The enhanced high _- resolution TEM (HRTEM) image of Co@Co3O4 _- NC (Fig. 2f) shows distinct interplanar spacings of 0.242 nm and 0.466 nm, corresponding to the lattice fringes with (311) and (111) Cubic Co ₃ O ₄ . These fringes were found around another distinct domain with a planar spacing of 0.204 nm, corresponding to metallic Co with (111) lattice fringes. For comparison, HRTEM images of Co _- NCs (Fig. 2c) and Co3O4 _- NCs (Fig. 2i) showed interplanar spacings of 0.204 nm and 0.242 nm, corresponding to the (111) lattice fringes of Co (JCPDS No. _.15-0806 ) and (311) lattice fringes _of Co3O4 (JCPDS No. 42-1467). Apparently, the carbon layer surrounds the Co@ _Co3O4 particles _. These results are consistent with expectations for partially oxidized Co nanoparticles anchored in the carbon framework.

2.2 Cyclic voltammetric characteristics of glucose on Co@Co ₃ O ₄ -NC/GCE

It can be seen from Figure 3a that both Co@Co ₃ O ₄ -NC/GCE and Co ₃ O ₄ -NC/GCE (refer to Co@Co ₃ O ₄ -NC/GCE for the preparation method) show two pairs of redox peaks , anodic peaks at about 0.64V and 0.3V, and cathodic peaks at about 0.55V and 0.25V. A pair of redox peaks around 0.55V and 0.64V corresponds to the reversible transition between Co3 ⁺ and Co4 ⁺ , while the peaks around 0.25V and 0.55V can be attributed to the transition between Co2 ⁺ and Co3 ⁺ . These two reversible reactions can be expressed schematically as:

and

After adding glucose, Co@Co ₃ O ₄ -NC/GCE exhibited an obvious catalytic current peak at the intensity of 0.64 V, about 2.78 mAcm ^-2 . In contrast, the redox peaks of Co ₃ O ₄ -NC/GCE and Co-NC/GCE increased slightly, while bare GCE showed very weak oxidation response to glucose. In Figure 3b, we investigated the electrochemical activity of GCE and Co@Co ₃ O ₄ -NC/GCE in 5mMK ₃ Fe(CN) ₆ /0.1M KCl solution by cyclic voltammetry. It can be seen that the peak potential separation at Co@Co ₃ O ₄ -NC/GCE is lower than that at GCE, which indicates that the presence of Co@Co ₃ O ₄ -NC can accelerate the electron transport rate. According to the Randles-Sevcik equation, the electroactive area of Co@Co ₃ O ₄ -NC/GCE is larger, 0.093 cm ² , compared to the GCE of 0.063 cm ² .

The CVs of Co@Co ₃ O ₄ -NC/GCE at different scan rates were obtained in 0.1 M KOH. The results showed that both the anodic and cathodic peak currents increased in the range of 2 to 200 ^mV s (Fig. 4a). Figure 4b shows a good linear relationship between the anodic and cathodic peak currents and the scan rate, indicating a surface-controlled electrochemical process.

2.3 Glucose sensing

As shown in Fig. 3a, the current increase with the addition of glucose at the anodic peak at 0.64 V was much stronger than that at the anodic peak at 0.3 V, which may indicate that the electrooxidation of glucose is dominated by Co ³⁺ /Co ⁴⁺ mediated rather than Co ²⁺ /Co ³⁺ in alkaline solution. Therefore, a potential of 0.64V vs. Hg/HgO was used for the following amperometric measurements. The reliability of Co@Co ₃ O ₄ -NC/GCE for glucose oxidation was further evaluated by the current-time curves in 0.1 M KOH at a current of 0.64 V vs. Hg/HgO. Figure 5a shows the voltammogram of the stair box and the stepwise increase in amperometric current at different glucose concentrations. The current response reached a steady-state current within 5 s (inset of Fig. 5a), revealing the fast charge carrier dynamics involved in the glucose electrooxidation process. The fitted curve of this glucose sensor is shown in Fig. 5b. Since the electrochemical oxidation of glucose on _{Co3S4 -} G is a surface-catalyzed reaction, the Langmuir isotherm theory was used to fit the curve ³² . According to the Langmuir isotherm theory, the glucose concentration (Cglucose S) adsorbed on the catalyst surface can be expressed as:

where KA is the adsorption equilibrium constant, _Ct is the total molar concentration of active sites _{on Co3S4 -} G, which is constant, and C _glucose is the concentration of glucose in the bulk electrolyte. Thus, at a given applied potential, the current density response J produced by the electrochemical oxidation of glucose is approximately proportional to _{C glucose S} with a rate constant of KB . Therefore, by defining a new constant, J can be expressed as K=K _A K _B C _t as follows:

As shown in Figure 5, K = 0.447 and K _A = 0.126 in this equation can have a good fit constant (R = 0.986). So J can be expressed as:

In addition, the calibration curve of this glucose sensor exhibited a linear range of 0.01-4 mM, and the sensitivity of this sensor at a signal-to-noise ratio of 3 was 251.9 μA mM ⁻¹ cm ⁻² with a detection limit of 0.3 μM.

In biological systems, dopamine (DA), uric acid (UA), and ascorbic acid (AA) often coexist with glucose, which may affect the detection of glucose. Therefore, selectivity is an important parameter for glucose sensors. Interference experiments were performed by successive additions of 0.1 mM glucose and 0.1 mM other interferents in 0.1 M NaOH. As can be seen in Figure 5c, Co@Co3O4 _{- NC} /GCE has a significant response to glucose, but negligible response to interfering substances, and the current density increases again with additional glucose addition. The selectivity of Co@Co ₃ O ₄ -NC/GCE is favorable considering that the concentration of glucose in physiological environment is more than 30 times that of these interfering species. The stability of Co@Co ₃ O ₄ -NC/GCE was investigated by measuring the amperometric response for a long time. Figure 5d shows the amperometric response to 0.1 mM glucose over 7 days. After 7 days, the final amperometric response is about 95.2% of the original response, indicating the excellent stability of Co@Co ₃ O ₄ -NC/GCE. _The reproducibility of Co@Co3O4 _- NC/GCE was also evaluated by measuring the cyclic voltammetry response of five Co@Co3O4 _- NC/GCE parallel electrodes to ₁ mM glucose in 0.1 m NaOH. The relative standard deviation (RSD) of the anode peak current density was 5.6%, indicating good reproducibility.

2.4 Practical applications of glucose sensors

To demonstrate the feasibility of Co@Co ₃ O ₄ -NC/GCE in practical analysis, the glucose concentration in medical glucose injection was tested by amperometric method. Glucose recovery and RSD for glucose injections were performed by spiking three known levels of glucose according to standard addition methods. Electrochemical measurements were performed three times (n=3). Glucose injection is not processed prior to use. The recoveries of the three assays ranged from 97% to 104%, and the RSD of the three assays was less than 2.6%, indicating an efficient and sensitive determination of glucose on Co@Co ₃ O ₄ -NC/GCE. This indicates the great potential of Co@Co ₃ O ₄ -NC/GCE for practical and reliable glucose analysis.

In conclusion, Co@Co ₃ O ₄ -NC/GCE has been shown to be an efficient catalyst electrode for glucose oxidation under alkaline conditions. When used as a non-enzymatic glucose electrochemical sensor, it showed high sensitivity and selectivity with satisfactory stability and reproducibility. Moreover, the sensor shows great potential for determining glucose in practical analysis.

Claims (10)

1. A preparation method of N-doped carbon-wrapped Co@Co ₃ O ₄ core-shell particle polyhedron, comprising the following steps: 1) carbonizing the ZIF-67 crystals in an inert atmosphere, and cooling to room temperature to obtain a Co-NC composite material; 2) Heating the Co-NC composite material to 220±20° C. in air, and keeping the temperature at 200±1° C. for 24±5 h, to obtain the N-doped carbon-wrapped Co@Co ₃ O ₄ core-shell particle polyhedron. 2. The method according to claim 1, wherein: in the step 1), the inert atmosphere is nitrogen, the temperature of the carbonization is 800±50°C, and the time is 1～3h; The heating rate of the carbonization temperature is 1˜5° C. min ⁻¹ . 3. method according to claim 1 and 2 is characterized in that: in described step 1), described ZIF-67 crystal is prepared according to the following method: by cobalt nitrate and 2-methylimidazole in ethanol The reaction is carried out in the solution, and after the reaction is completed, the precipitate is collected by centrifugation; the precipitate is washed with ethanol and then dried. 4 . The method according to claim 1 , wherein in the step 1), the heating rate is 2±1° C. min ⁻¹ . 5 . 5. The N-doped carbon-wrapped Co@Co ₃ O ₄ core-shell particle polyhedron prepared by the method according to any one of claims 1-4. 6. The application of the N-doped carbon-wrapped Co@Co ₃ O ₄ core-shell particle polyhedron of claim 4 in the preparation of a non-enzymatic electrochemical glucose sensor. 7. A non-enzymatic electrochemical glucose sensor, comprising a working electrode, characterized in that: the working electrode is a Co@Co ₃ O ₄ core-shell particle polyhedron layer whose surface is modified with the N-doped carbon wrapping of claim 4 the base electrode. 8 . The non-enzymatic electrochemical glucose sensor according to claim 7 , wherein the base electrode is a glassy carbon electrode; the N-doped carbon-wrapped Co@Co ₃ O ₄ core-shell particle polyhedron in the working electrode The dosage relative to the base electrode is 0.357 mg·cm ⁻² ; In the non-enzymatic electrochemical glucose sensor, a platinum electrode is used as a counter electrode, Hg/HgO is used as a reference electrode, and KOH or NaOH is used as an electrolyte. 9. A method for detecting glucose, comprising the steps of: using the non-enzymatic electrochemical glucose sensor according to claim 7 or 8 to electrochemically detect a solution containing glucose. 10. The method according to claim 9, wherein: the solution containing glucose also contains at least one of the following substances: dopamine, uric acid and ascorbic acid; The reference electrode in the non-enzymatic electrochemical glucose sensor is Hg/HgO, and the working voltage of the non-enzymatic electrochemical glucose sensor is 0.64V.

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