Multi-acid-group complex with electrocatalytic activity on H2O2 and preparation method of multi-acid-group complex

Abstract

The invention provides a polyacid-based complex with electrocatalytic activity on H2O2 and a preparation method of the polyacid-based complex. The molecular formula of the polyacid-based complex with the electrocatalytic activity on H2O2 is [Zn (H2O) 4 (TeMo6O24)] [Zn (Hpca) (H2O) 5] 2.6 H2O. The multi-acid-group complex disclosed by the invention has electrocatalytic activity on H2O2, and H2O2 can be detected by an electrochemical method.

Description

Technical Field

[0001] The invention belongs to the cross-technical field of coordination chemistry and nanomaterials, and specifically relates to a polyacid-based complex having electrocatalytic activity for H2O2 and a preparation method thereof. Background Art

[0002] Hydrogen peroxide (H2O2) is a typical peroxide with functions such as disinfection, bleaching and sterilization. It is widely used in the preservation, insurance and aseptic packaging of foods such as dairy products and aquatic products. In addition, H2O2, as an important signal molecule, participates in the regulation of signal transduction processes such as cell growth, differentiation, and apoptosis in plants, and plays a vital role in regulating metabolism in organisms. Studies have shown that H2O2 may cause genetic DNA damage in the human body, induce gene mutations in the human body and then cause cancer; as a strong oxidant, H2O2 will quickly consume antioxidant substances in the body, resulting in reduced immunity and resistance of the human body; H2O2 can also decompose in the human body to produce hydroxyl free radicals, which will not only destroy cell structures and cause damage to human organs, but also cause cardiovascular, diabetes and other diseases. Therefore, it is necessary to design a material for efficient detection of H2O2.

[0003] Existing H2O2 detection methods include spectrophotometry, chemiluminescence, chromatography, fluorescence, etc., but the detection process of these methods is relatively complicated, expensive, time-consuming, and low in sensitivity. Therefore, it is of great significance to develop a suitable material for detecting H2O2. Summary of the invention

[0004] The object of the present invention is to provide a polyacid-based complex having electrocatalytic activity for H2O2 and a preparation method thereof. The polyacid-based complex has electrocatalytic activity and can be used for the detection of H2O2.

[0005] In order to achieve the above object, the present invention provides the following technical solution: a polyacid-based complex having electrocatalytic activity for H2O2, wherein the molecular formula of the polyacid-based complex is: [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O, the polyacid complex belongs to the trigonal system, and the space group is α=63.560°(7), β=68.971°(6), γ=63.534°(6).

[0006] Preferably, the [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O has the following coordination environment: one [TeMo6O 24 ] 6-The polyacid anions are connected by Zn(Ⅱ) to form a one-dimensional chain, and the one-dimensional chain is connected to the zinc isonicotinic acid complex through hydrogen bonds to form a two-dimensional layer.

[0007] The present invention also provides a method for preparing the polyacid-based complex having electrocatalytic activity for H2O2, which adopts the following technical scheme: The method for preparing the polyacid-based complex having electrocatalytic activity for H2O2 comprises the following steps: (1) ZnCl2, isonicotinic acid and NH4[TeMo6O 24 ]·7H2O is added into deionized water and stirred to obtain a mixed solution; (2) the pH value of the mixed solution is adjusted, the temperature is raised to 80-120°C and the reaction is carried out for 90-100 hours, after the reaction is completed, the solid-liquid separation is carried out, and the obtained white block crystals are washed to obtain the polyacid-based complex having electrocatalytic activity for H2O2.

[0008] Preferably, in step (1), NH4[TeMo6O 24 ]·The molar ratio of 7H2O, ZnCl2 and isonicotinic acid is 1:(5-7):3.3.

[0009] Preferably, in step (2), a hydrochloric acid solution is used to adjust the pH of the mixed solution to 2-4.

[0010] The present invention also provides a working electrode for electrocatalysis of H2O2, which adopts the following technical scheme: a working electrode for electrocatalysis of H2O2, wherein the working electrode for electrocatalysis of H2O2 contains the polyacid-based complex having electrocatalytic activity for H2O2 as described above.

[0011] The present invention also provides a method for preparing the working electrode for electrocatalysis of H2O2 as described above, which adopts the following technical scheme: the method for preparing the working electrode for electrocatalysis of H2O2 as described above comprises the following steps: S1. mixing and grinding the polyacid-based complex having electrocatalytic activity for H2O2 with graphite powder, adding paraffin oil, and stirring to obtain a paste mixture; S2. loading the paste mixture into an electrode rod and compacting it to obtain the working electrode for electrocatalysis of H2O2.

[0012] Preferably, in step S1, the mass ratio of the polyacid-based complex having electrocatalytic activity for H2O2 to the graphite powder is 1:10.

[0013] The present invention also provides the use of the polyacid-based complex having electrocatalytic activity for H2O2 as described above in a working electrode for electrocatalysis of H2O2, which adopts the following technical scheme: the use of the polyacid-based complex having electrocatalytic activity for H2O2 as described above or the working electrode for electrocatalysis of H2O2 as described above in electrocatalysis of H2O2.

[0014] Preferably, the polyacid-based complex having electrocatalytic activity for H2O2 or the working electrode for electrocatalysis of H2O2 is used to detect whether a sample contains H2O2.

[0015] Beneficial effects:

[0016] The polyacid-based complex of the present invention has electrocatalytic activity for H2O2, and can be used for electrocatalysis of H2O2, and further can realize detection of H2O2 by electrochemical method.

[0017] The synthesis method of the polyacid-based complex having electrocatalytic activity for H2O2 of the present invention is simple, the synthesis cycle is short, and the synthesis yield is high. The isonicotinic acid organic ligand used has an N-containing group, which is easy to coordinate with metal ions, accelerates the crystallization process of the polyacid-based complex and shortens the synthesis cycle. The reason for using isonicotinic acid in the synthesis method of the present invention is that the N in the isonicotinic acid ligand is easy to coordinate with metal ions to form a two-dimensional layer structure (if isonicotinic acid is not added or other N-containing organic ligands are used to replace isonicotinic acid during the preparation of the polyacid-based complex of the present invention, a single crystal measurable product cannot be prepared, and the target complex cannot be obtained).

[0018] The polyacid-based complex synthesized by the method of the invention has high crystallinity and clear structure and is relatively easy to be separated from the reaction medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0020] Figure 1 [Zn(H2O)4(TeMo6O 24 )][Infrared spectrum of Zn(Hpca)(H2O)5]2·6H2O.

[0021] Figure 2 [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O powder diffraction spectrum.

[0022] Figure 3 [Zn(H2O)4(TeMo6O 24 Solid UV diffuse reflectance analysis diagram of [Zn(Hpca)(H2O)5]2·6H2O.

[0023] Figure 4 [Zn(H2O)4(TeMo6O 24)][Coordination environment diagram of Zn(Hpca)(H2O)5]2·6H2O.

[0024] Figure 5 [Zn(H2O)4(TeMo6O 24 )][One-dimensional chain diagram of Zn(Hpca)(H2O)5]2·6H2O.

[0025] Figure 6 The material of Example 1 contains [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O working electrode cyclic voltammetry characteristic curve.

[0026] Figure 7 The material of Example 1 contains [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O working electrode scan rate and linear fitting diagram of the bipolar peaks.

[0027] Figure 8 The material of Example 1 contains [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O working electrode after adding different concentrations of H2O2.

[0028] Fig. 9 This is the cyclic voltammetry characteristic curve of the working electrode of Comparative Example 1. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0030] The present invention will be described in detail below in conjunction with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0031] When the inventors were solving the problem of how to better realize the detection of H2O2 and expand the detection method of H2O2, they thought of polyacid-based complexes, which are new functional materials that combine metal-organic complexes (MOCs) and polyacids (POMs). They can not only show the superior structural characteristics of MOCs such as high specific surface area, high stability, and tailorability, but also effectively combine the oxygen-rich surface, chemical stability, structural diversity, reversible multi-electron conversion and unique redox activity of POMs, thereby achieving the purpose of dual regulation of material structure and performance, and have potential application value in catalysis, detection and optics. Furthermore, through research and invention, a new polyacid-based complex with electrocatalytic activity for H2O2 was obtained. The polyacid-based complex has electrocatalytic activity and can be used for the detection of H2O2.

[0032] The molecular formula of the polyacid complex having electrocatalytic activity for H2O2 in the embodiment of the present invention is: [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O.

[0033] In a preferred embodiment of the polyacid-based complex having electrocatalytic activity for H2O2 of the present invention, the polyacid-based complex belongs to the trigonal system and has a space group of α=63.560°(7), β=68.971°(6), γ=63.534°(6); [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O has the following coordination environment: one [TeMo6O 24 ] 6- The polyacid anions are connected by Zn(Ⅱ) to form a one-dimensional chain, and the one-dimensional chain is connected to the zinc isonicotinic acid complex through hydrogen bonds to form a two-dimensional layer.

[0034] The method for preparing a polyacid-based complex having electrocatalytic activity for H2O2 according to an embodiment of the present invention comprises the following steps: (1) reacting ZnCl2, isonicotinic acid and NH4[TeMo6O 24 ]·7H2O is added to deionized water and stirred to obtain a mixed solution; (2) the pH value of the mixed solution is adjusted, the temperature is raised to 80-120°C (for example, 80°C, 90°C, 100°C, 110°C or 120°C) and the reaction is carried out for 90-100h (for example, 90h, 92h, 94h, 96h, 98h or 100h), after the reaction is completed, the solid-liquid separation is carried out, and the obtained white block crystals are washed to obtain a polyacid-based complex having electrocatalytic activity for H2O2.

[0035] In a preferred embodiment of the method for preparing a polyacid-based complex having electrocatalytic activity for H2O2 of the present invention, in step (1), NH4[TeMo6O 24 ]·The molar ratio of 7H2O, ZnCl2 and isonicotinic acid is 1:(5-7):3.3 (for example, 1:5:3.3, 1:5.5:3.3, 1:6.1:3.3, 1:6.7:3.3 or 1:7:3.3). If the usage ratio of the three is lower or higher than the optimal molar ratio of the reaction, the yield of the polyacid-based complex is reduced or the target product cannot be obtained.

[0036] In a preferred embodiment of the method for preparing a polyacid-based complex having electrocatalytic activity for H2O2 of the present invention, in step (1), the stirring time is 30-120 min (for example, 30 min, 50 min, 70 min, 90 min, 110 min or 120 min) to achieve sufficient mixing and dissolution of the raw materials; in step (2), the pH of the mixed solution is adjusted to between 2 and 4 (for example, 2, 2.5, 3, 3.5 or 4). When the pH is lower than this range, the yield of the complex will be reduced, and when the pH is higher than this range, the target compound cannot be obtained.

[0037] In a preferred embodiment of the method for preparing a polyacid-based complex having electrocatalytic activity for H2O2 of the present invention, in step (2), a hydrochloric acid solution is used to adjust the pH of the mixed solution; the concentration of the hydrochloric acid solution is 1 mol / L. The main reason for using hydrochloric acid for acid adjustment is that Cl -1 It will not affect the experimental results of this experiment, but the phosphate in phosphoric acid will participate in the coordination of the crystal structure, and the strong oxidizing property of nitric acid will also have a great influence on the structure of the target complex. In summary, hydrochloric acid is more appropriate.

[0038] In a preferred embodiment of the method for preparing a polyacid-based complex having electrocatalytic activity for H2O2 of the present invention, in step (1), NH4[TeMo6O 24 ]·The concentration of 7H2O is 10-15 mol / L (for example, 10 mol / L, 11 mol / L, 12 mol / L, 13 mol / L, 14 mol / L or 15 mol / L).

[0039] The present invention also provides a working electrode for electrocatalysis of H2O2. The working electrode for electrocatalysis of H2O2 in the embodiment of the present invention contains the polyacid-based complex as described above.

[0040] The present invention also proposes a method for preparing a working electrode for electrocatalysis of H2O2 as described above. The method for preparing a working electrode for electrocatalysis of H2O2 in an embodiment of the present invention comprises the following steps: S1. Mixing and grinding a polyacid-based complex with graphite powder, adding paraffin oil, and stirring to obtain a paste mixture; S2. Loading the paste mixture into an electrode rod and compacting it to obtain a working electrode for electrocatalysis of H2O2. The amount of paraffin oil used is preferably such that the graphite powder reaches a viscous state that can be shaped. Too much or too little will not achieve the purpose of shaping the working electrode. Preferably, when the amount of graphite powder is 100 mg, the amount of paraffin oil used is about 10-25 μL (for example, 10 μL, 15 μL, 20 μL or 25 μL).

[0041] In a preferred embodiment of the method for preparing an electrode for electrocatalysis of H2O2 of the present invention, in step S1, the mass ratio of the polyacid-based complex to the graphite powder is about 1:10. Among them, when the mass ratio of the polyacid-based complex to the graphite powder is 1:10, it is the best peak ratio; if the ratio of the polyacid-based complex is too low, it will make the redox peak difficult to scan out and the conductivity will be poor; if the ratio of the polyacid-based complex is too high, it will cause waste of samples.

[0042] The present invention also proposes the use of the polyacid-based complex or working electrode having electrocatalytic activity for H2O2 as described above: the use of the polyacid-based complex having electrocatalytic activity for H2O2 as described above or the working electrode for electrocatalysis of H2O2 as described above in electrocatalysis of H2O2.

[0043] Preferably, the polyacid-based complex or the working electrode for electrocatalysis of H2O2 as described above is used to detect whether a sample contains H2O2 (for example, at least can be used to qualitatively detect whether a sample contains H2O2).

[0044] More preferably, the following method can be used to detect whether the sample contains H2O2: the working electrode, reference electrode (Ag|AgCl electrode can be used) and auxiliary electrode (platinum wire electrode can be used) for electrocatalysis of H2O2 of the present invention are placed in an electrolyte solution (for example, an electrolyte solution with a volume ratio of 0.1M H2SO4 and 0.5M Na2SO4 of 1:1 can be used), and the oxidation peak current and reduction peak current before and after the addition of the sample are observed at a specific scan rate to see whether there are changes, so as to determine whether the sample contains H2O2 (if the sample contains H2O2, the oxidation-reduction peak current decreases after the sample is added).

[0045] The following is a detailed description of the polyacid-based complex having electrocatalytic activity for H2O2 and its preparation method and application through specific examples.

[0046] The reagents used in the following examples are all commercially available; the sources of some reagents are shown in Table 1 below:

[0047] Table 1 Reagents required for the experiment

[0048]

[0049] Example 1

[0050] The polyacid-based complex having electrocatalytic activity for H2O2 in this embodiment is prepared by a method comprising the following steps:

[0051] (1) 0.1 mol NH4[TeMo6O 24 ]·7H2O, 0.67mol ZnCl2, 0.33mol isonicotinic acid (pca), and 8mL deionized water were mixed and stirred for two hours to obtain a mixed solution;

[0052] (2) The pH value of the mixed solution was adjusted to pH=3 using a 1 mol / L HCl solution, and then the mixed solution was added to a 25 mL polytetrafluoroethylene-lined stainless steel autoclave and reacted at 120° C. for 4 days to obtain white block crystals; the mixture was washed with deionized water for 3 times and dried to obtain the polyacid-based complex [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O, dried at room temperature.

[0053] The working electrode for electrocatalysis of H2O2 of this embodiment contains the above-mentioned polyacid-based complex.

[0054] The working electrode for electrocatalysis of H2O2 in this embodiment is prepared by a method comprising the following steps:

[0055] S1. Add the above-mentioned polyacid-based complex and graphite powder (the mass ratio of the polyacid-based complex and the graphite powder is 1:10, and the amount of graphite powder is 100 mg) to a mortar for grinding, then add 10 to 25 μl of paraffin oil, stir with a glass rod until a paste is formed, and obtain a paste mixture;

[0056] S2. The paste mixture is placed into an electrode rod and compacted with a copper rod to obtain the working electrode for electrocatalysis of H2O2 in this embodiment.

[0057] The working electrode for electrocatalysis of H2O2 in this embodiment is used for the detection of H2O2 in the sample:

[0058] The working electrode for electrocatalysis of H2O2 of this embodiment was used, Ag|AgCl was used as the reference electrode, and the platinum wire electrode was used as the auxiliary electrode. The electrochemical behavior of the working electrode was studied in 0.1M H2SO4 and 0.5M Na2SO4 solutions. First, the redox peak current at different scan rates was studied to increase with the increase of the scan rate, and was linearly related to the scan rate, indicating that the electrochemical reaction of the working electrode was a surface-controlled process. With the increase of the scan rate, the peak potentials of the oxidation peak and the reduction peak produced a small shift in the positive and negative directions, respectively, △Ep increased, but E(0f) remained almost unchanged. When H2O2 solutions of different concentrations were added to the electrolyte solution, the current of the redox peak decreased, indicating that H2O2 had a catalytic oxidation reaction on the electrode surface, thereby proving that the polyacid-based complex can be used for H2O2 detection.

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 1 is that the working electrode is pure graphite (in the process of preparing the working electrode, the polyacid-based complex [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O was replaced by an equal amount of graphite powder), and the rest were consistent with Example 1.

[0061] Experimental example

[0062] 1. Characterization of the polyacid complex with electrocatalytic activity for H2O2 in Example 1:

[0063] (1) Infrared spectroscopy

[0064] The infrared spectrum of the polyacid-based complex of Example 1 was measured on an FT-IR spectrometer with a scanning range of 400-4000 cm -1 ;like Figure 1 The characteristic absorption peak of the polyacid is at 930 cm -1 -667cm -1 ; 1413cm -1 The absorption peak is attributed to the stretching vibration of the pyridine ring skeleton of the pca ligand molecule; at 3300 cm -1 The left and right are the absorption vibration peaks of water molecules.

[0065] (2) Powder diffraction

[0066] The powder diffraction data were collected on a SmartLab powder X-ray diffractometer using molybdenum target X-rays; the density data collection scan range was 5 ° to 50 ° , scanning speed is 5 ° / min; Jade program was used for data fitting, and Mercury was used for simulation conversion of single crystal structure powder diffraction spectrum.

[0067] like Figure 2 As shown, the powder X-ray diffraction spectrum of the polyacid-based complex of Example 1 is substantially consistent with the fitted PXRD spectrum, indicating that the polyacid-based complex is a pure phase.

[0068] (3) Ultraviolet diffuse reflectance analysis

[0069] Obtained on a Shimadzu UV-240 ultraviolet-visible diffuse reflectance spectrometer from Japan Figure 3 The solid ultraviolet diffuse reflectance analysis diagram shown in the figure is tested at room temperature. The test method is to first use 600-800 mg BaSO4 to press a tablet for baseline calibration, and then mix 40-60 mg of the polyacid-based complex of Example 1 with BaSO4. It can be seen from the spectrum that the compound has a strong absorption band at 200-300nm. The intersection of the tangent line of the obtained curve and the X=0 axis is its band gap value. It can be seen from the spectrum that the polyacid-based complex is a potential semiconductor material with electrocatalytic activity.

[0070] 2. Determination of the crystal structure of the polyacid complex synthesized in Example 1:

[0071] Single crystals of appropriate size were selected using a microscope and the diffractometers were Xcalibur, Atlas, Gemini (graphite monochromator, Mo-Ka, ) Collect diffraction data; Scanning mode The structural analysis was completed using the olex2 1.5 program; the least squares method was used to determine the coordinates of all non-hydrogen atoms, and the theoretical hydrogenation method was used to obtain the positions of hydrogen atoms; the crystal structure was refined using the least squares method; Figure 4-Figure 5 The basic coordination conditions and extended structures of the polyacid-based complex synthesized in Example 1 are shown; some parameters of its crystallographic diffraction point data collection and structure refinement are shown in Tables 2 and 3:

[0072] Table 2 Crystal data of polyacid complexes of Example 1

[0073]

[0074]

[0075] Table 3 Important bond lengths of the polyacid complexes of Example 1 and bond angle (°)

[0076]

[0077] 3. Experimental study on electrocatalysis of H2O2 by the polyacid-based complex synthesized in Example 1

[0078] A carbon paste electrode modified with the polyacid-based complex of Example 1 (the working electrode for electrocatalysis of H2O2 in Example 1) was used as the working electrode, Ag|AgCl was used as the reference electrode, and a platinum wire electrode was used as the auxiliary electrode, in an electrolyte solution of 0.1M H2SO4 and 0.5MNa2SO4, with the ratio of the two being 1:1 (the pH value of the electrolyte solution was 1.7, which was the optimal condition for the test. Replacing the electrolyte solution would result in a change in the pH value, thereby affecting the offset of the redox peak position in the electrochemical test and causing a large error).

[0079] Figure 6 The cyclic voltammetry characteristic curves at different scan rates are shown. In the range of 600 to -300 mV, there are three pairs of obvious reversible redox peaks. According to formula E 1 / 2 =(E pa +E pc ) / 2, the average peak potentials of the carbon paste electrode modified with the polyacid-based complex were determined to be +209.325, +49.384 and -177.474 mV, corresponding to the redox couple of the Mo center in the polyacid-based complex.

[0080] like Figure 7 As shown, the redox peak current gradually increases with the scan rate from 20 to 600 mV / s and is linearly related to the scan rate, indicating that the redox process of the working electrode is controlled by the surface and has excellent electrochemical redox performance.

[0081] like Figure 8 As shown in the figure, at a scan rate of 60mV / s, after adding H2O2 solution to the electrolyte solution of 0.1M H2SO4 and 0.5M Na2SO4, the redox peak current drops rapidly. As the H2O2 content increases, the oxidation peak current decreases continuously, while the corresponding reduction peak current drops sharply. When the H2O2 content is 25mM, the oxidation peak current and the reduction peak current are significantly different from the sample without H2O2. During the electrochemical detection of H2O2, H2O2 on the anode is oxidized to oxygen, and electrons are released at the same time; while the electrons on the cathode are reduced, and during the reduction process, H2O2 is reduced to water. Therefore, the concentration of H2O2 in the electrolyte solution will gradually decrease, and when the concentration of H2O2 decreases to zero, the redox peak current will return to the initial state. This shows that the polyacid-based complex has good electrocatalytic activity for the reduction of H2O2 and can be used as a potential electrocatalytic material.

[0082] 4. The working electrode in Comparative Example 1 was placed in an electrolyte solution of 0.1M H2SO4 and 0.5M Na2SO4, with Ag|AgCl as the reference electrode and a platinum wire electrode as the auxiliary electrode. Electrochemical detection was performed at a scan rate of 60mV / s. During the experiment, regardless of whether H2O2 was added to the electrolyte, the detection results were the same as Fig. 9 shown.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A polyacid-based complex having electrocatalytic activity for H2O2, characterized in that: The molecular formula of the polyacid complex is: [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O, the polyacid complex belongs to the trigonal system, and the space group is α=63.560°(7), β=68.971°(6), γ=63.534°(6).

2. The polyacid-based complex having electrocatalytic activity for H2O2 according to claim 1, characterized in that: The [Zn(H2O)4(TeMo6O 24 )][Zn(Hpca)(H2O)5]2·6H2O has the following coordination environment: one [TeMo6O 24 ] 6- The polyacid anions are connected by Zn(Ⅱ) to form a one-dimensional chain, and the one-dimensional chain is connected to the zinc isonicotinic acid complex through hydrogen bonds to form a two-dimensional layer.

3. The method for preparing a polyacid-based complex having electrocatalytic activity for H2O2 according to claim 1 or 2, characterized in that: The steps include: (1) ZnCl2, isonicotinic acid and NH4[TeMo6O 24 ]·7H2O is added into deionized water and stirred to obtain a mixed solution; (2) adjusting the pH of the mixed solution, raising the temperature to 80-120° C. and reacting for 90-100 hours, separating the solid and the liquid after the reaction, and washing the obtained white block crystals to obtain the polyacid-based complex having electrocatalytic activity for H2O2.

4. The method for preparing a polyacid-based complex having electrocatalytic activity for H2O2 according to claim 3, characterized in that: In step (1), NH4[TeMo6O 24 ]·The molar ratio of 7H2O, ZnCl2 and isonicotinic acid is 1:(5-7):3.

3.

5. The method for preparing a polyacid-based complex having electrocatalytic activity for H2O2 according to claim 3, characterized in that: In step (2), a hydrochloric acid solution is used to adjust the pH of the mixed solution to 2-4.

6. A working electrode for electrocatalysis of H2O2, characterized in that: The working electrode for electrocatalysis of H2O2 contains the polyacid-based complex having electrocatalytic activity for H2O2 as claimed in claim 1 or 2.

7. The method for preparing a working electrode for electrocatalysis of H2O2 according to claim 6, characterized in that: The steps include: S1. The polyacid-based complex having electrocatalytic activity for H2O2 is mixed and ground with graphite powder, paraffin oil is added, and stirred to obtain a paste mixture; S2. The paste mixture is loaded into an electrode rod and compacted to obtain the working electrode for electrocatalysis of H2O2.

8. The method for preparing a working electrode for electrocatalysis of H2O2 according to claim 7, characterized in that: In step S1, the mass ratio of the polyacid-based complex having electrocatalytic activity for H2O2 to the graphite powder is 1:

10.

9. Use of the polyacid-based complex having electrocatalytic activity for H2O2 as claimed in claim 1 or the working electrode for electrocatalysis of H2O2 as claimed in claim 6 in electrocatalysis of H2O2.

10. The use according to claim 9, characterized in that The polyacid-based complex having electrocatalytic activity for H2O2 or the working electrode for electrocatalysis of H2O2 is used to detect whether a sample contains H2O2.

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