Preparation method and application of NiFe-LDH / CeO2 composite nanomaterial

Abstract

This invention discloses a preparation method and application of a NiFe-LDH / CeO2 composite nanomaterial, belonging to the field of electrochemical sensors. The invention prepares a composite nanomaterial of NiFe-LDH-coated CeO2 nanowires. Coating the NiFe-LDH / CeO2 composite nanomaterial on the surface of a glassy carbon electrode and a screen-printed electrode effectively enhances electron transfer in the electrode-catalyzed glucose oxidation reaction, thereby increasing the electrode material's sensitivity to glucose detection.

Description

Technical Field

[0001] The invention relates to a preparation method and application of a NiFe-LDH / CeO2 composite nanomaterial, and belongs to the field of electrochemical sensors. Background Art

[0002] Diabetes is a chronic disease that develops when the pancreas fails to produce enough insulin to regulate blood sugar or when the body cannot effectively use the insulin it produces. If diabetes is not treated well, other health problems may follow, such as eye and foot complications, kidney disease, stroke, and heart disease. Strict control of blood sugar levels is crucial to preventing or reducing the risk of diabetes and its complications. Regular monitoring of physiological blood sugar levels is essential to effectively treat and prevent any hyperglycemia or hypoglycemia.

[0003] Glucose biosensors are divided into two major categories: enzymatic and non-enzymatic. Non-enzymatic glucose electrochemical sensors have shown great potential due to their low price, ultrahigh sensitivity, and low environmental dependence, and have received extensive attention and research. The selection of catalysts for non-enzymatic glucose sensors is a key factor affecting the sensitivity and selectivity of glucose detection. Nanomaterials, such as noble metal nanomaterials (Au, Ag, Pd), transition metal materials (Ni, Cu), metal oxides (CuO, NiO), alloys (Pt-Pb, Pt-Cu), metal-organic frameworks (MOFs), and layered double hydroxides (LDH), have been widely used in the construction of non-enzymatic glucose electrochemical sensors due to their large reactive surface area, good catalytic efficiency, and strong adsorption capacity.

[0004] Layered double hydroxide (LDH) is a two-dimensional material with a unique anionic layered structure. Its general formula is a brucite-like layer composed of divalent and trivalent metal ions (M(II) and M(III)). The chemical composition formula of LDH is [M II 1-x M III x (OH)2] x+ A x / n n- .mH2O, where M II and M III are divalent and trivalent metal cations, M II The ion is usually Ca 2+ 、Mn 2+ Mg 2+ 、Fe 2+ 、Co 2+ 、Ni 2+ 、Cu 2+ or Zn 2+ etc., M. IIIIt can be Al 3+ 、Fe 3+ 、Mn 3+ or Co 3+ etc., A. n- Interlayer anions, such as CO3 2- , NO 3- and Cl - etc., usually existing between layers together with crystal water. LDH is a classic electrocatalyst due to its large surface area, good adsorption capacity, high chemical stability and efficient anion exchange performance. These characteristics also make LDH widely used in electrocatalysis, adsorption, biosensing, and energy storage. At present, a variety of LDHs have been used in electrochemical sensing platforms to detect small biological molecules such as hydrogen peroxide, lactic acid, ascorbic acid, and glucose, such as NiCo-LDH, NiFe-LDH, ZnAl-LDH, CoCu-LDH, NiAl-LDH, NiMn-LDH, etc. However, due to the inherent low conductivity and slow diffusion of electrolytes of LDH materials, as well as the easy accumulation of interlayer electrostatic forces during the preparation process, which leads to blockage of the inner surface of the material, the utilization efficiency of its active sites is reduced, hindering the practical application of LDH-based materials in glucose sensors. Therefore, integrating LDH into various structures, such as active supports or skeletons, is considered to be beneficial not only for maintaining the structure of LDH but also for improving its electrocatalytic activity. In addition, fine-tuning the nanostructure morphology of LDH is also considered to be an effective strategy to increase the electrochemical surface area and further improve the exposure of active sites in electrocatalysis. Summary of the Invention

[0005] In order to solve the problems of poor conductivity, easy agglomeration and insufficient catalytic ability of LDH materials in the prior art, one of the objects of the present invention is to provide a method for preparing a NiFe-LDH / CeO2 nanocomposite material. Starting from the micromorphology design of the catalyst (LDH), the excellent properties of CeO2 nanomaterials, such as non-toxicity, biocompatibility, good chemical stability, high mechanical strength and good electron transfer ability, are utilized to modify NiFe-LDH to form a heterostructure, improve the stacking and conductivity of the NiFe-LDH structure, thereby enhancing its catalytic performance, and thereby making a modified electrode to obtain an electrochemical sensor with good electron transfer ability, excellent stability and high sensitivity. The preparation method of the NiFe-LDH / CeO2 nanocomposite material is as follows:

[0006] (1) Preparation of CeO2 nanowires: Ce(NO3)3·6H2O and NaOH were dissolved in deionized water to obtain Ce(NO3)3·6H2O solution and NaOH solution, respectively. The NaOH solution was slowly added dropwise to the Ce(NO3)3·6H2O solution under continuous stirring to obtain mixed solution I. The mixed solution I was subjected to a hydrothermal reaction. After the reaction was completed, the mixture was cooled to room temperature. The solid was collected and washed by centrifugation with ethanol. The obtained solid was then dried and calcined to obtain white CeO2 nanowire powder.

[0007] (2) Synthesis of NiFe-LDH / CeO2: Nickel nitrate (Ni(NO3)2·6H2O), ferric nitrate (Fe(NO3)3·9H2O) and urea are dissolved in deionized water to form a mixed solution II; ammonium fluoride is dissolved in deionized water to form an ammonium fluoride solution; the ammonium fluoride solution is slowly added to the mixed solution II under continuous stirring to form a mixed solution III, and stirring is continued. The white CeO2 nanowire powder obtained in step (1) is then added to the mixed solution III to obtain a mixed solution IV, and the mixed solution IV is subjected to a hydrothermal reaction. The solid is collected and washed by centrifugation with ethanol, and finally the obtained solid is dried to obtain a brown solid powder NiFe-LDH / CeO2 nanocomposite material.

[0008] Preferably, the molar concentration of the Ce(NO3)3·6H2O solution in step (1) is 5-15 mmol / L, and the molar concentration of the NaOH solution is 0.3-0.7 mol / L; the volume ratio of the Ce(NO3)3·6H2O solution and the NaOH solution in the mixed solution I is 1:1-1:5.

[0009] Preferably, the hydrothermal reaction conditions in step (1) are 100-140° C. for 12-48 hours; and the calcination temperature is 300-700° C. for 1-5 hours.

[0010] Preferably, in step (2), the total molar concentration of Ni and Fe metal ions in the mixed solution II is 5.4 mmol / L, wherein the molar concentration ratio of Ni ions to Fe ions is 1:1 to 4:1; the molar concentration of urea is 2.6 mol / L; the molar concentration of the ammonium chloride solution is 2 mol / L; the volume ratio of the ammonium fluoride solution in the mixed solution III to the mixed solution II is 1:1 to 1:7; and the amount of CeO2 nanowire powder added to the mixed solution III is 0.5 mg / mL to 1.17 mg / mL.

[0011] Preferably, the hydrothermal reaction conditions in step (2) are 120° C. and the time is 12 h.

[0012] Preferably, the drying temperature in step (1) and step (2) is both 50°C.

[0013] The second purpose of the present invention is to provide an application of a NiFe-LDH / CeO2 nanocomposite material in the preparation of electrode materials.

[0014] Preferably, the NiFe-LDH / CeO2 nanocomposite material is prepared into a dispersion, and the dispersion is evenly drop-coated onto the surface of the electrode material.

[0015] Preferably, the dispersion is prepared by dissolving 1 to 5 mg of NiFe-LDH / CeO2 nanocomposite material in 1 mL of a mixture of ethanol and water with a mass concentration of 0.00005% to 0.0002% nafion, wherein the volume ratio of ethanol to water is 1:1, and ultrasonically treating the mixture for 30 minutes to prepare a uniform dispersion with a concentration of 1 to 5 mg / mL.

[0016] Preferably, the electrode material includes a glassy carbon electrode and a screen-printed electrode.

[0017] Preferably, the preparation method of the screen-printed electrode is as follows: using polyvinyl chloride (PVC) as a flexible substrate and a screen printing plate as a mold, a three-electrode system screen-printed electrode (SPE) is prepared by a high-temperature ink screen printing process, wherein the working electrode and the counter electrode are carbon electrodes, and the reference electrode is an Ag / AgCl electrode; the SPE electrode pretreatment method is an electrochemical treatment method, and the SPE electrode is heated to 0.1 mol L -1 Cyclic voltammetry was performed in PBS (pH 7.0) solution for 10 cycles at a scan rate of 0.05 V s -1 , the scanning range was 0-1.5 V, and then rinsed with distilled water to obtain a screen-printed electrode (SPE).

[0018] The third object of the present invention is to provide an application of an electrode prepared using a NiFe-LDH / CeO2 nanocomposite material in detecting glucose.

[0019] Beneficial effects of the present invention

[0020] (1) Compared with the traditional NiFe-LDH catalyst, the NiFe-LDH / CeO2 composite nanomaterial designed in the present invention is a heterogeneous structure of NiFe-LDH nanosheets grown on CeO2 nanowire cores. The interaction between the solid-solid interface and the modification of CeO2 can effectively regulate the electronic structure of the metal sites on the LDH surface and improve the electrocatalytic activity of the material.

[0021] (2) The present invention innovatively designs NiFe-LDH / CeO2 composite nanomaterials. The good electron transport ability of its CeO2 nanowires promotes the charge migration on the surface of NiFe-LDH, improves the problem of easy stacking of LDH, and enhances the electron transport ability of the composite nanomaterial, greatly improving the catalytic performance of glucose.

[0022] (3) The NiFe-LDH / CeO2 composite nanomaterial modified electrode designed in the present invention has excellent detection limit, sensitivity, and stability for glucose detection, which broadens the application of LDH materials in the field of electrochemical sensors.

[0023] (4) Compared with traditional electrode detection devices, the NiFe-LDH / CeO2 / SPE electrode of the present invention has the characteristics of simple operation, cost-effectiveness, portability, and rapid response, which is conducive to the rapid and portable detection of blood glucose and has broad market potential.

[0024] (5) The nickel-based metal used in the present invention has a high space utilization rate of up to 74.05%. The high utilization rate accelerates the catalytic glucose oxidation process, making the electrode material have excellent electrochemical properties; Fe-based materials are also widely used catalyst materials because of their low price, excellent redox ability, fast electron transfer speed and high catalytic activity. Combining them with Ni-based materials, the synergistic effect of the two metals can further promote the catalytic oxidation of glucose by the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 These are scanning electron microscope characterization images of CeO2, Ni3Fe1-LDH and Ni3Fe1-LDH / CeO2 prepared in Example 1.

[0026] Figure 2 The X-ray diffraction spectra of CeO2, Ni3Fe1-LDH and Ni3Fe1-LDH / CeO2 prepared in Example 1 were obtained.

[0027] Figure 3 The different electrodes (CeO2 / GCE, NiFe-LDH / GCE and NiFe-LDH / CeO2 / GCE) prepared in Example 1 were heated in 0.1 mol / L KCl and 5 mmol / L [Fe(CN)6] 3- / 4- Cyclic voltammograms and electrochemical impedance spectroscopy in electrolyte solutions, where Figure a shows the cyclic voltammograms and electrochemical impedance spectroscopy of different electrodes (CeO2 / GCE, NiFe-LDH / GCE, and NiFe-LDH / CeO2 / GCE) in 0.1 mol / L KCl and 5 mmol / L [Fe(CN)6] 3- / 4-Cyclic voltammograms in electrolyte solutions; Figure b shows the cyclic voltammograms of different electrodes (CeO2 / GCE, NiFe-LDH / GCE and NiFe-LDH / CeO2 / GCE) in 0.1 mol / L KCl and 5 mmol / L [Fe(CN)6] 3- / 4- Electrochemical impedance spectroscopy in electrolyte solution.

[0028] Figure 4 These are the cyclic voltammograms of different electrodes (GCE, CeO2 / GCE, Ni3Fe1-LDH / GCE and Ni3Fe1-LDH / CeO2 / GCE) prepared in Example 1 in the presence or absence of 0.5 mmol / L glucose.

[0029] Figure 5 The cyclic voltammograms of NiFe-LDH / GCE electrodes with different Ni:Fe molar ratios (1:1, 2:1, 3:1 and 4:1) to 0.05 mmol / L glucose in Example 1 and Example 2 are shown.

[0030] Figure 6 The cyclic voltammograms of NiFe-LDH / CeO2 composite nanomaterials containing different masses of CeO2 nanowires (30, 40, 50, 60, 70 mg) against 0.05 mmol / L glucose in Example 1 and Example 3 are shown.

[0031] Figure 7 Schematic diagram of the screen-printed electrode (SPE) prepared in Example 4 and a schematic diagram of the screen-printed electrode detecting glucose, wherein Figure a is a schematic diagram of the screen-printed electrode (SPE); Figure b is a schematic diagram of the screen-printed electrode detecting glucose.

[0032] Figure 8 This is the IT curve of the NiFe-LDH / CeO2 / SPE electrode prepared in Example 4 when different concentration gradients of glucose are continuously added at 0.55V.

[0033] Figure 9 It curves of the NiFe-LDH / CeO2 / SPE electrode prepared in Example 4 at 0.55 V with the addition of different analytes (50 μmol / L glucose, 0.5 mmol / L ascorbic acid (AA), 0.5 mmol / L L-cysteine ​​(L-Cystrine), 0.5 mmol / L citric acid (CA) and 1 mol / L sodium chloride (NaCl)).

[0034] Figure 10 This is the reproducibility test of glucose on four identical NiFe-LDH / CeO2 / SPE electrodes prepared in Example 4.

[0035] Figure 11 The stability of the NiFe-LDH / CeO2 / SPE electrode prepared in Example 4 for glucose detection within 7 days. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. However, the following embodiments are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0037] Example 1

[0038] A method for preparing a Ni3Fe1-LDH / CeO2 / GCE electrode is as follows:

[0039] (1) Preparation of CeO2 nanowires: 0.1 mmol of Ce(NO3)3·6H2O and 0.015 mol of NaOH were dissolved in 10 mL and 30 mL of deionized water, respectively. The NaOH solution was slowly added dropwise to the Ce(NO3)3·6H2O solution under constant stirring to obtain a mixed solution I. The mixed solution I was poured into a reactor and subjected to a hydrothermal reaction at 120°C for 24 hours. The reactor was then cooled to room temperature, and the solid was collected and washed three times by centrifugation with ethanol. The obtained solid was then dried in an oven at 50°C overnight. Finally, the solid product was placed in a muffle furnace and calcined at 500°C for 3 hours to obtain white CeO2 nanowire powder.

[0040] (2) Synthesis of Ni3Fe1-LDH: 0.2 mmol of nickel nitrate (Ni(NO3)2·6H2O), 0.07 mmol of iron nitrate (Fe(NO3)3·9H2O) and 0.13 mol of urea were dissolved in 50 mL of deionized water to form a mixed solution II; at the same time, 0.02 mol of ammonium fluoride was dissolved in 10 mL of deionized water to form an ammonium fluoride solution. The ammonium fluoride solution was slowly added to the mixed solution II under continuous stirring to form a mixed solution III, and stirring was continued for 0.5 hours. The mixed solution III was transferred to a high-pressure reactor and subjected to a hydrothermal reaction at 120°C for 12 hours. The solid was then collected and washed three times by centrifugation with ethanol. Finally, the obtained solid was dried in a vacuum drying oven at 50°C overnight to obtain a brown solid powder NiFe-LDH nanomaterial.

[0041] (3) Synthesis of Ni3Fe1-LDH / CeO2: 0.2 mmol of nickel nitrate (Ni(NO3)2·6H2O), 0.07 mmol of iron nitrate (Fe(NO3)3·9H2O) and 0.13 mol of urea were dissolved in 50 mL of deionized water to form a mixed solution IV; at the same time, 0.02 mol of ammonium fluoride was dissolved in 10 mL of deionized water to form an ammonium fluoride solution. The ammonium fluoride solution was slowly added to the mixed solution IV under continuous stirring to form a mixed solution V, and stirring was continued for 0.5 hours. Subsequently, 50 mg of the CeO2 solid powder prepared in step (1) was added to the mixed solution V to form a light green mixed solution VI. The above mixed solution VI was transferred to a high-pressure reactor and subjected to a hydrothermal reaction at 120°C for 12 hours. The solid was then collected and washed three times by centrifugation with ethanol. Finally, the obtained solid was dried in a vacuum drying oven at 50°C overnight to obtain a brown solid powder Ni3Fe1-LDH / CeO2 nanocomposite material.

[0042] (4) Preparation of electrodes: The glassy carbon electrode was pre-polished and, if necessary, ultrasonically cleaned to remove surface impurities and oil stains, and named as a GCE electrode. 3 mg of CeO2 nanowires, Ni3Fe1-LDH, and Ni3Fe1-LDH / CeO2 nanocomposites prepared in steps (1), (2), and (3) were dissolved in 1 mL of a mixture of ethanol and water with a mass concentration of 0.0001% nafion, with a ratio of ethanol to water of 1:1. The mixture was ultrasonically treated for 30 minutes to prepare a uniform dispersion with a concentration of 3 mg / mL. 3 μL of the above-mentioned different uniform dispersions were then drop-coated on the surface of different glassy carbon electrodes and dried at room temperature overnight to obtain different CeO2 / GCE, Ni3Fe1-LDH / GCE, and Ni3Fe1-LDH / CeO2 / GCE electrodes.

[0043] The prepared CeO2 nanowire powder, Ni3Fe1-LDH and Ni3Fe1-LDH / CeO2 nanocomposites were observed using a scanning electron microscope. Figure 1 As shown in the SEM image, it can be clearly seen that CeO2 has a distinct linear structure ( Figure 1 (a) Ni3Fe1-LDH is a flower-like structure formed by flakes or flakes combined ( Figure 1 (b) Ni3Fe1-LDH / CeO2 composite nanomaterial is a heterogeneous structure of Ni3Fe1-LDH nanosheets grown on CeO2 nanowire cores ( Figure 1 (c)). At the same time, the prepared CeO2, Ni3Fe1-LDH and Ni3Fe1-LDH / CeO2 nanocomposites were analyzed by X-ray diffraction (XRD), as shown in Figure 2. Figure 2 As shown, the characteristic crystal planes of each material can be clearly observed in the X-ray diffraction spectrum, indicating that the Ni3Fe1-LDH / CeO2 modified electrode material prepared by the present invention is successful.

[0044] Example 2

[0045] In this example, NiFe-LDH / CeO2 nanocomposites with different molar ratios of Ni and Fe were prepared, and NiFe-LDH / CeO2 / GCE electrodes were prepared using NiFe-LDH / CeO2 nanocomposites with different molar ratios of Ni and Fe. The preparation method was the same as that in Example 1, except that the molar concentrations of nickel nitrate and ferric nitrate in the mixed solution IV in step (3) were as shown in Table 1.

[0046] Table 1 Molar concentrations of nickel nitrate and ferric nitrate in mixed solution II of Example 2

[0047]

[0048] The three electrode materials prepared in this example are Ni1Fe1-LDH / CeO2 modified electrode material, Ni2Fe1-LDH / CeO2 modified electrode material and Ni4Fe1-LDH / CeO2 modified electrode material.

[0049] Example 3

[0050] In this example, NiFe-LDH / CeO2 composite nanomaterials containing CeO2 nanowires of varying masses were prepared. NiFe-LDH / CeO2 / GCE electrodes were prepared using these different NiFe-LDH / CeO2 nanocomposites. The preparation method was the same as in Example 1, except that the amount of CeO2 nanowire powder used in step (3) was different, thereby synthesizing NiFe-LDH / CeO2 composite nanomaterials containing CeO2 nanowires of varying masses. The amount of CeO2 nanowire powder used in this example is shown in Table 2.

[0051] Table 2 Amount of CeO2 nanowire powder used in Example 2

[0052] <![CDATA[Dosage (mg) of CeO2 nanowire powder]]> 30 40 60 70

[0053] Example 4

[0054] Preparation method of NiFe-LDH / CeO2 / SPE portable electrode

[0055] The preparation of CeO2 nanowires in step (1) and the synthesis of NiFe-LDH / CeO2 in step (3) of this embodiment are exactly the same as those in Example 1. The preparation method of the electrode in step (4) is as follows: using polyvinyl chloride (PVC) as a flexible substrate and a screen printing plate as a mold, a three-electrode system screen-printed electrode (SPE) is prepared by a high-temperature ink screen printing process, wherein the working electrode and the counter electrode are carbon electrodes, and the reference electrode is an Ag / AgCl electrode ( Figure 7 a); The SPE electrode pretreatment method is electrochemical treatment, and in 0.1 mol L -1 Cyclic voltammetry was performed in PBS (pH 7.0) solution for 10 cycles at a scan rate of 0.05 V s -1 , scanning range 0-1.5V, and then rinsed with distilled water. Subsequently, 3 μL of a 3 mg / mL NiFe-LDH / CeO2 nanocomposite dispersion (the volume ratio of ethanol to water in the dispersion was 1:1) was drop-coated onto the SPE electrode surface and dried overnight at room temperature to obtain a NiFe-LDH / CeO2 / SPE portable electrode. Four identical electrode materials were prepared using the same method in this example.

[0056] The various materials and electrodes prepared in Examples 1 to 4 were subjected to relevant performance experiments.

[0057] Different modified electrodes prepared in Example 1 (CeO2 (CeO2 / GCE), Ni3Fe1-LDH (NiFe-LDH / GCE), Ni3Fe1-LDH / CeO2 (NiFe-LDH / CeO2 / GCE)) were prepared and reacted in 0.1 mol / L KCl and 5 mmol / L [Fe(CN)6] 3- / 4- The modification process of the electrode was characterized by cyclic voltammetry and electrochemical impedance spectroscopy in an electrolyte solution composed of Figure 3 a) shows that the redox peak current of the cyclic voltammetry curves of the electrodes modified with CeO2, Ni3Fe1-LDH and Ni3Fe1-LDH / CeO2 increases in sequence; Figure 3 As shown in b): the charge transfer resistance of the electrode modified by CeO2 and Ni3Fe1-LDH is significantly larger than that of the Ni3Fe1-LDH / CeO2 modified electrode, indicating that the electron transfer ability of the nanomaterial after the composite of CeO2 and Ni3Fe1-LDH is enhanced. Figure 3 This shows that the electrode modification process prepared in Example 1 was successful.

[0058] Electrochemical detection of glucose using the different modified electrodes prepared in Example 1 (bare electrode (GCE), CeO2 (CeO2 / GCE), Ni3Fe1-LDH (NiFe-LDH / GCE), and Ni3Fe1-LDH / CeO2 (NiFe-LDH / CeO2 / GCE)) was performed to obtain cyclic voltammograms of glucose. Using the Ni3Fe1-LDH / CeO2 modified electrode, the current signal was significantly enhanced, significantly improving the sensitivity of the sensor. Figure 4 This shows that the electrode modification process prepared in Example 1 is successful and can detect glucose with high sensitivity.

[0059] Take the NiFe-LDH modified electrodes (Ni1Fe1-LDH, Ni2Fe1-LDH, Ni3Fe1-LDH, Ni4Fe1-LDH) with different Ni and Fe molar ratios prepared in Example 1 and Example 2, and perform electrochemical detection on the glucose to be measured to obtain the cyclic voltammogram of glucose. Figure 5 It can be seen that when the molar ratio of Ni and Fe is 3:1 (Ni3Fe1-LDH), the electrocatalytic performance of NiFe-LDH for glucose is optimal.

[0060] The NiFe-LDH / CeO2 composite nanomaterial electrodes containing different masses of CeO2 nanowires (30, 40, 50, 60, 70 mg) prepared in Example 1 and Example 3 were used to perform electrochemical detection of glucose to obtain the cyclic voltammogram of glucose. Figure 6 It can be seen that when the mass of CeO2 is 50 mg, the electrocatalytic performance of NiFe-LDH / CeO2 composite nanomaterial electrode for glucose is optimal.

[0061] The detection range of glucose detected by the SPE electrochemical sensor prepared in Example 4 is: Figure 8 The it curve of the NiFe-LDH / CeO2 / SPE electrode prepared by the present invention when different concentrations of glucose are added. As can be seen from the figure, the peak current of glucose has a good linear correlation with its concentration. The equation is: pa (μA)=2.883+121.732C(μmol / L)(R 2 =0.987), the sensitivity is 1816.89μA·mM -1 cm -2 The detection limit is 0.013 μmol / L. This shows that the electrochemical sensor prepared by the present invention has high sensitivity and low detection limit, and can be used to sensitively detect glucose.

[0062] Anti-interference ability test of the SPE electrochemical sensor prepared in Example 4, Figure 9The NiFe-LDH / CeO2 / SPE electrode prepared by the present invention was sequentially added with 0.5mmol / L ascorbic acid (AA), 0.5mmol / L L-cysteine ​​(L-Cystrine), 0.5mmol / L citric acid (CA) and 1mol / L sodium chloride (NaCl) in a 0.1mol / L NaOH electrolyte to simulate a real test environment. As can be seen from the figure, after the interfering substance was added, the current value did not change significantly and the current continued to increase after glucose was added again, indicating that the added interfering substance had no effect on the sensor's detection of glucose. Therefore, this result shows that the prepared electrochemical sensor has good selectivity and anti-interference ability for the detection of glucose.

[0063] Verification of the reproducibility and stability of the SPE electrochemical sensor prepared in Example 4, Figure 10 For the four identical NiFe-LDH / CeO2 / SPE electrodes prepared in the present invention, it can be seen that the peak current of glucose maintains good repeatability. Figure 11 The stability of the NiFe-LDH / CeO2 / SPE electrode for glucose detection after 2 days and 7 days is shown in Table 1. Figure 11 It can be seen from the graph that the peak current of glucose maintained good stability within 7 days, indicating that the prepared electrochemical sensor has good reproducibility and stability.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a NiFe-LDH / CeO2 composite nanomaterial, characterized in that: The NiFe-LDH / CeO2 composite nanomaterial is a composite nanomaterial in which NiFe-LDH nanosheets encapsulate CeO2 nanowires. The specific preparation method is as follows: (1) Preparation of CeO2 nanowires: Ce(NO3)3·6H2O and NaOH were dissolved in deionized water to obtain Ce(NO3)3·6H2O solution and NaOH solution, respectively. The NaOH solution was slowly added dropwise to the Ce(NO3)3·6H2O solution under continuous stirring to obtain mixed solution I. The mixed solution I was subjected to a hydrothermal reaction. After the reaction was completed, the mixture was cooled to room temperature, the solid was collected and washed by centrifugation with ethanol, and then the obtained solid was dried and calcined to obtain white CeO2 nanowire powder. (2) Synthesis of NiFe-LDH / CeO2: nickel nitrate, iron nitrate and urea were dissolved in deionized water to form a mixed solution II; at the same time, ammonium fluoride was dissolved in deionized water to form an ammonium fluoride solution; The ammonium fluoride solution is slowly added to the mixed solution II under continuous stirring to form a mixed solution III, and stirring is continued. The white CeO2 nanowire powder obtained in step (1) is then added to the mixed solution III to obtain a mixed solution IV. The mixed solution IV is subjected to a hydrothermal reaction, the solid is collected and washed by centrifugation with ethanol, and the obtained solid is dried to obtain a brown solid powder NiFe-LDH / CeO2 nanocomposite material.

2. The method for preparing the NiFe-LDH / CeO2 composite nanomaterial according to claim 1, wherein: The molar concentration of the Ce(NO3)3·6H2O solution in step (1) is 5-15 mmol / L, and the molar concentration of the NaOH solution is 0.3-0.7 mol / L; the volume ratio of the Ce(NO3)3·6H2O solution to the NaOH solution in the mixed solution I is 1:1-1:

5.

3. The method for preparing the NiFe-LDH / CeO2 composite nanomaterial according to claim 1, wherein: The conditions of the hydrothermal reaction in step (1) are 100-140° C. for 12-48 hours; the calcination temperature is 300-700° C. for 1-5 hours.

4. The method for preparing the NiFe-LDH / CeO2 composite nanomaterial according to claim 1, wherein: In step (2), the total molar concentration of Ni and Fe metal ions in the mixed solution II is 5.4 mmol / L, wherein the molar concentration ratio of Ni ions to Fe ions is 1:1 to 4:1, and the molar concentration of urea is 2.6 mol / L; the molar concentration of the ammonium chloride solution is 2 mol / L; the volume ratio of the ammonium fluoride solution in the mixed solution III to the mixed solution II is 1:1 to 1:7; and the amount of CeO2 nanowire powder added to the mixed solution III is 0.5 mg / mL to 1.17 mg / mL.

5. The method for preparing the NiFe-LDH / CeO2 composite nanomaterial according to claim 1, wherein: The hydrothermal reaction conditions in step (2) are 120° C. and the time is 12 h.

6. The method for preparing the NiFe-LDH / CeO2 composite nanomaterial according to claim 1, wherein: The drying temperature in step (1) and step (2) is both 50°C.

7. Use of the NiFe-LDH / CeO2 nanocomposite material prepared according to claim 1 in the preparation of electrode materials, characterized in that: The NiFe-LDH / CeO2 nanocomposite material is prepared into a dispersion liquid, and the dispersion liquid is evenly drop-coated on the surface of the electrode material, wherein the electrode material is a glassy carbon electrode or a screen-printed electrode.

8. The use according to claim 7, characterized in that: The working electrode and the counter electrode of the screen-printed electrode are carbon electrodes, and the reference electrode is an Ag / AgCl electrode. Before the dispersion is dripped, the screen-printed electrode needs to be pretreated by electrochemical treatment.

9. The use according to claim 8, characterized in that: The electrochemical treatment conditions were as follows: 10 cycles of cyclic voltammetry scanning were performed in 0.1 mol / L PBS (pH 7.0) solution at a scan rate of 0.05 V s -1 , the scanning range is 0 ~ 1.5V, and then rinse with distilled water.

10. Use of the electrode material prepared according to claim 7 in detecting blood sugar.

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