Ru-Co3O4 nano material and preparation method and electrochemical detection application thereof

Abstract

The invention provides a Ru-Co3O4 nano material, a preparation method of the Ru-Co3O4 nano material and an application of the Ru-Co3O4 nano material in electrochemical detection. The nano material is a Ru-doped Co3O4 nano tube. According to the Ru-Co3O4 nano material as well as the preparation method and the application thereof, the Ru-Co3O4 nano material is utilized to construct a high-selectivity modified electrode, high-selectivity and high-sensitivity electrochemical detection of specific heavy metal ions (Pb) in water is realized, and the experiment efficiency is improved while the experiment cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical detection, and in particular relates to a Ru-Co3O4 nano material and a preparation method and electrochemical detection application thereof. Background Art

[0002] With the acceleration of industrialization, water pollution is becoming increasingly serious. Trace amounts of Pb(II) in water can have toxic effects on animals and plants and have a persistent, cumulative and amplifying effect, which can easily damage the ecological environment. In addition, lead can interact with calcium ion binding sites in the human body, thus greatly affecting people's health. Therefore, the monitoring of heavy metal ions is particularly important, especially in key areas of heavy metal pollution supervision, such as mines, chemical plants, textile mills, etc.

[0003] Among the currently known methods for detecting heavy metal ions, electrochemical sensing has become one of the important means due to its simple equipment, sensitive detection, easy integration and field application, and has been widely used in the detection of heavy gold ions in actual water bodies. In particular, with the rapid development of chemically modified electrodes and the rise of nanomaterials, many researchers have achieved highly sensitive detection of trace heavy metal ions. For example, Li et al. optimized the electronic structure distribution of N atoms by intercalating Mn single atoms into g-C3N4 substrates to achieve highly sensitive detection of Pb(II) (J.Hazard.Mater.,2022,435,129009.). Chen et al. achieved highly sensitive detection of Pb(II) by making P atoms occupy CoSe 2-x The Se vacancy in the middle modulates the electronic structure of the P atom, making the detection sensitivity of As(III) as high as 1.11μAppb -1 (Anal. Chem. 2022, 94, 3211.).

[0004] However, the background composition of real water bodies is relatively complex. When multiple heavy metal pollutants coexist, they will seriously interfere with the detection signal. For example, Song et al. found that in a mixed solution of multiple metal ion components, Cd(II) and Cu(II) have a significant promoting and inhibiting effect on the electrochemical signal of As(III) (Anal. Chem. 2022, 94, 6225-6233.). Zhou et al. 2-x An in-depth analysis of the mutual interference between Cu(II) and Cd(II) at the sensitive interface was conducted (Anal.Chem.2018,90,4328-4337).

[0005] Therefore, constructing highly selective modified electrodes is of great significance to improving the accuracy and practicality of electroanalytical methods. However, there is currently no systematic research on the selective detection of heavy metal ions by electroanalysis, and the design of catalytic materials that suppress single interfering ions mainly relies on experimental experience. Therefore, it is particularly important to obtain nanomaterials with sensitive interfaces that have highly selective detection of different heavy metal ions. Summary of the invention

[0006] Based on the above technical problems, the present invention provides a Ru-Co3O4 nanomaterial, a preparation method and an electrochemical detection application thereof. A highly selective modified electrode is constructed using Ru-Co3O4 nanomaterial, which realizes highly selective and highly sensitive electrochemical detection of specific heavy metal ions (Pb) in water, reduces experimental costs and improves experimental efficiency.

[0007] The invention provides a Ru-Co3O4 nano material, wherein the nano material is a Co3O4 nano tube doped with Ru.

[0008] Preferably, the doping amount of Ru is 0.85-2.55 wt % of Co 3 O 4 .

[0009] Preferably, the nanotube has a diameter of 80-150 nm and a length of 1-100 μm.

[0010] The present invention also provides a method for preparing Ru-Co3O4 nanomaterials, comprising the following steps:

[0011] S1. Add cobalt salt, urea and ammonium fluoride into water to obtain solution A; add ammonium ruthenium salt into water to obtain solution B;

[0012] S2, adding solution B to solution A for hydrothermal reaction to obtain Ru-Co(OH)2 precursor;

[0013] S3. After calcining the Ru-Co(OH)2 precursor, the Ru-Co3O4 nanomaterial is obtained.

[0014] Preferably, the cobalt salt is at least one of cobalt nitrate, cobalt chloride or cobalt sulfate, and the ruthenium salt is at least one of ruthenium chloride, ruthenium nitrate or ruthenium acetate;

[0015] Preferably, the molar ratio of the cobalt salt, urea and ammonium fluoride is 1:2-5:3-6; the molar ratio of the cobalt salt and ruthenium salt is 145-440:1.

[0016] Preferably, the hydrothermal reaction temperature is 120-150° C. and the time is 4-8 hours.

[0017] Preferably, the calcination temperature is 300-400° C., and the calcination time is 1-3 h.

[0018] The present invention also proposes an application of the Ru-Co3O4 nanomaterial or the Ru-Co3O4 nanomaterial prepared by the above preparation method in electrochemical detection of heavy metal ions.

[0019] Preferably, the heavy metal ion is Pb(II).

[0020] Preferably, the application specifically includes: using the Ru-Co3O4 nanomaterial modified glassy carbon electrode as a working electrode, a reference electrode and a counter electrode to form a three-electrode system for electrochemical detection;

[0021] Preferably, the detection pH is 5, the enrichment time is 180s, and the enrichment voltage is -1.0V.

[0022] Beneficial effects:

[0023] (1) The Ru-Co3O4 nanomaterial described in the present invention is essentially a Ru-doped Co3O4 nanotube, which has a high specific surface area and porosity. When it is modified on the surface of a glassy carbon electrode to form a working electrode, it can be used for heavy metal detection in actual water samples in a three-electrode system.

[0024] (2) The Ru-Co3O4 nanomaterial modified electrode of the present invention has good electrochemical activity and conductivity, thus having a wide detection range, high sensitivity and good selectivity; for example, the detection limit (LOD) of Pb(II) is 0.03 μM, which is significantly lower than the 0.048 μM specified in the National Drinking Water Hygiene Standard (GB 5749-2022); the detection sensitivity of Pb(II) is as high as 68.52-70.23 μA / μM.

[0025] (3) The Ru-Co3O4 nanomaterial modified electrode of the present invention has strong anti-interference ability and excellent stability and repeatability when low concentration impurities coexist; for example, in 0.1-0.6 mmol / L Cd(II), Zn(II), Hg(II), and As(III) solutions, the response current value of 0.3 μM Pb(II) remains stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a scanning electron microscope image of the Ru-Co3O4 nanomaterial described in Example 2 of the present invention;

[0027] Figure 2 This is a schematic diagram of optimizing and screening experimental conditions when the Ru-Co3O4 nanomaterial described in Example 2 of the present invention is used for electrochemical detection;

[0028] Figure 3This is the SWASV response curve of the Ru-Co3O4 nanomaterial described in Example 2 of the present invention for electrochemical detection of Pb(II);

[0029] Figure 4 This is the SWASV response curve of the Ru-Co3O4 nanomaterial described in Example 2 of the present invention when it is used for electrochemical detection after Cd(II), Hg(II), As(III) and Zn(II) are added to the Pb(II) solution;

[0030] Figure 5 The stability and repeatability curve of the Ru-Co3O4 nanomaterial described in Example 2 for electrochemical detection of Pb(II);

[0031] Figure 6 The SWASV response curves of the Co3O4 nanomaterial described in Comparative Example 1 of the present invention and the Fe-Co3O4 nanomaterial described in Comparative Example 2 to Pb(II) when used for electrochemical detection. DETAILED DESCRIPTION

[0032] Hereinafter, the present invention will describe the technical solution in detail through specific embodiments, but it should be clearly stated that these embodiments are for illustration only and are not to be construed as limiting the scope of the present invention.

[0033] Cobalt nitrate hexahydrate [Co(NO3)2·6H2O], urea [CO(NH2)2], ammonium fluoride [NH4F], and hydrated ruthenium chloride [RuCl3·nH2O] were purchased from Sinopharm Chemical Reagent Co., Ltd. All chemical reagents involved were of analytical grade and used directly without other purification or cleansing treatment.

[0034] Example 1

[0035] This embodiment provides a Ru-Co3O4 nanomaterial, the preparation method of which includes:

[0036] (1) 1.05 mmol of cobalt nitrate hexahydrate, 3.36 mmol of urea and 5.0 mmol of ammonium fluoride were dissolved in 25 mL of deionized water and stirred to form solution A; 7.2 μmol of hydrated ruthenium chloride was dissolved in 10 mL of deionized water and stirred to form solution B;

[0037] (2) Solution B was quickly added to solution A, and the mixture was stirred at room temperature for 2 h. The resulting mixed solution was transferred to a 50 mL polytetrafluoroethylene-lined stainless steel autoclave, heated at 130 ° C for 6 h, and washed three times by centrifugation with deionized water and ethanol alternately, and then vacuum dried overnight to obtain a Ru-Co(OH)2 precursor;

[0038] (3) The Ru-Co(OH)2 precursor is placed in a muffle furnace and calcined at 350°C for 2 hours to obtain the Ru-Co3O4 nanomaterial.

[0039] Example 2

[0040] This embodiment provides a Ru-Co3O4 nanomaterial, the preparation method of which includes:

[0041] (1) 1.05 mmol of cobalt nitrate hexahydrate, 3.36 mmol of urea and 5.0 mmol of ammonium fluoride were dissolved in 25 mL of deionized water and stirred to form solution A; 14.4 μmol of hydrated ruthenium chloride was dissolved in 10 mL of deionized water and stirred to form solution B;

[0042] (2) Solution B was quickly added to solution A, and the mixture was stirred at room temperature for 2 h. The resulting mixed solution was transferred to a 50 mL polytetrafluoroethylene-lined stainless steel autoclave, heated at 130 ° C for 6 h, and washed three times by centrifugation with deionized water and ethanol alternately, and then vacuum dried overnight to obtain a Ru-Co(OH)2 precursor;

[0043] (3) The Ru-Co(OH)2 precursor is placed in a muffle furnace and calcined at 350°C for 2 hours to obtain the Ru-Co3O4 nanomaterial.

[0044] The Ru-Co3O4 nanomaterials in the above examples were tested by scanning electron microscopy, and the results were as follows: Figure 1 As shown, refer to Figure 1 It can be seen that the Ru-Co3O4 nanomaterial is a Ru-doped Co3O4 nanotube, the diameter of the nanotube is about 150nm, and the length is about 5μm.

[0045] Example 3

[0046] This embodiment provides a Ru-Co3O4 nanomaterial, the preparation method of which includes:

[0047] (1) 1.05 mmol of cobalt nitrate hexahydrate, 3.36 mmol of urea and 5.0 mmol of ammonium fluoride were dissolved in 25 mL of deionized water and stirred to form solution A; 28.8 μmol of hydrated ruthenium chloride was dissolved in 10 mL of deionized water and stirred to form solution B;

[0048] (2) Solution B was quickly added to solution A, and the mixture was stirred at room temperature for 2 h. The resulting mixed solution was transferred to a 50 mL polytetrafluoroethylene-lined stainless steel autoclave, heated at 130 ° C for 6 h, and washed three times by centrifugation with deionized water and ethanol alternately, and then vacuum dried overnight to obtain a Ru-Co(OH)2 precursor;

[0049] (3) The Ru-Co(OH)2 precursor is placed in a muffle furnace and calcined at 350°C for 2 hours to obtain the Ru-Co3O4 nanomaterial.

[0050] Comparative Example 1

[0051] This comparative example proposes a Co3O4 nanomaterial, the preparation method of which includes:

[0052] (1) 1.05 mmol of cobalt nitrate hexahydrate, 3.36 mmol of urea, and 5.0 mmol of ammonium fluoride were dissolved in 25 mL of deionized water and stirred to form solution A;

[0053] (2) Solution A was transferred into a 50 mL polytetrafluoroethylene-lined stainless steel autoclave, heated at 130 °C for 6 h, washed three times by centrifugation with deionized water and ethanol alternately, and then vacuum dried overnight to obtain a Ru-Co(OH)2 precursor;

[0054] (3) The Ru-Co(OH)2 precursor is placed in a muffle furnace and calcined at 350°C for 2h to obtain the Co3O4 nanomaterial.

[0055] Comparative Example 2

[0056] This comparative example proposes a Fe-Co3O4 nanomaterial, the preparation method of which includes:

[0057] (1) 1.05 mmol of cobalt nitrate hexahydrate, 3.36 mmol of urea and 5.0 mmol of ammonium fluoride were dissolved in 25 mL of deionized water and stirred to form solution A; 14.4 μmol of hydrated ferric chloride was dissolved in 10 mL of deionized water and stirred to form solution B;

[0058] (2) Solution B was quickly added to Solution A, and the mixture was stirred at room temperature for 2 h. The resulting mixed solution was transferred to a 50 mL polytetrafluoroethylene-lined stainless steel autoclave, heated at 130 °C for 6 h, and washed three times by centrifugation with deionized water and ethanol alternately, and then vacuum dried overnight to obtain a Fe-Co(OH)2 precursor.

[0059] (3) The Fe-Co(OH)2 precursor is placed in a muffle furnace and calcined at 350°C for 2 hours to obtain the Fe-Co3O4 nanomaterial.

[0060] Test experiment

[0061] (1) Test system

[0062] The following electrochemical experiments were all performed on a CHI 760E electrochemical workstation produced by Shanghai Chenhua Instrument Co., Ltd., China.

[0063] A three-electrode system was used, in which a bare glassy carbon electrode (GCE) (3 mm in diameter) was used as the working electrode. It needed to be processed before use: first, it was polished with alumina powder with a particle size of 0.1 μm and 0.05 μm, respectively; then, the reversibility of the glassy carbon electrode was tested in a mixed solution of 0.005 mol / L K3[Fe(CN)6] and 0.1 mol / L KCl. When the potential difference between the oxidation peak and the reduction peak was less than 0.084 V, it indicated that the electrode had good reversibility; finally, the reversibility was tested in aqueous nitric acid solution (the volume ratio of nitric acid to water was 1:1), ethanol and In a deionized water solution, the polishing powder on the exposed GCE surface was removed by ultrasound for 90 s, and then the water droplets on the electrode surface were blown away with nitrogen to obtain a pretreated GCE electrode; the Ru-Co3O4 nanomaterial or Co3O4 nanomaterial, Fe-Co3O4 nanomaterial prepared in Example 2 and Comparative Examples 1 and 2 were added into water and stirred to obtain a 0.5 mg / mL suspension, 6 μL of the suspension was dropwise applied on the surface of the pretreated GCE electrode, and dried at room temperature to obtain a working electrode Ru-Co3O4 / GCE, Co3O4 / GCE or Fe-Co3O4 / GCE.

[0064] The reference electrode in the three-electrode system was Ag / AgCl (3 mol / L KCl), and the counter electrode was a platinum wire electrode.

[0065] (2) Samples to be tested

[0066] 0.1 mol / L acetic acid and sodium acetate stock solutions are prepared into HAc-NaAc buffer solutions with different pH values ​​according to different proportions, and an alkaline buffer solution can be obtained by adding 0.1 mol / L sodium hydroxide solution for adjustment.

[0067] PBS buffer with different pH values ​​was prepared by using 0.1 mol / L disodium hydrogen phosphate and potassium dihydrogen phosphate stock solutions in different proportions.

[0068] NH3·H2O-NH4Cl buffer solution was prepared by mixing 0.1 mol / L ammonia water and ammonium chloride stock solution in different proportions.

[0069] The heavy metal ion solutions of cadmium, lead, copper, mercury, and zinc were prepared by dissolving the corresponding nitrates in water. The arsenic ion solution was prepared by dissolving sodium arsenite in water, and the elemental quantitative analysis was performed using an inductively coupled plasma mass spectrometer (ICP-MS). Taking the lead ion solution as an example, 16.56 g of lead nitrate was dissolved in 400 mL of water and the volume was fixed in a 500 mL volumetric flask to prepare a lead ion solution with a concentration of 0.1 mol / L. The actual concentration of lead ions was then quantitatively determined by ICP-MS. Take 1 mL of the 0.1 mol / L lead ion solution and dilute it by 10 3 times to get 1×10-4 mol / L lead ion solution.

[0070] The preparation methods of other heavy metal ions are the same as that of lead ions.

[0071] (3) Test method

[0072] Square wave anodic stripping voltammetry (SWASV) was used to detect Pb(II).

[0073] Specifically, three windows were set to complete the electrochemical test, which corresponded to the enrichment window (window one), the redox window (window two), and the desorption window (window three). Among them, window one was the time-current program, with an enrichment voltage of -1.0V and a time of 180s; window two was the square wave anodic stripping voltammetry (SWASV) window, with a voltage setting range of -1.0-0V, a frequency of 25Hz, and an amplitude of 25mV; window three was the time-current window, with a desorption voltage of 1.0V and a time of 90s; the current limit of the three windows was 1×10 -4 A.

[0074] (4) Condition Optimization

[0075] By controlling variables, the type of buffer solution, pH value, enrichment voltage and enrichment time were optimized to obtain the optimal experimental conditions.

[0076] First, three Ru-Co3O4 / GCE working electrodes with the same content of Ru on their surfaces were immersed in 10mL HAc-NaAc, PBS, and NH3·H2O-NH4Cl buffer solutions at pH=5, respectively; the same concentration of Pb(II) solution (0.3μmol / L) was added to the three solutions, and the response current values ​​were compared at the same enrichment time and enrichment voltage, and the optimal buffer solution was HAc-NaAc. Under this buffer solution, five identical Ru-Co3O4 / GCE working electrodes were immersed in HAc-NaAc buffer solutions at pH=3, 4, 5, 6, and 7 at the same voltage and time, and the optimal pH was pH=5. Then, in the HAc-NaAc buffer solution at pH=5, the voltage and enrichment time were optimized in turn.

[0077] like Figure 2 As shown, Figure 2 In the figure, a represents the screening of buffer solution types, b represents the screening of pH values, c represents the screening of deposition potentials, and d represents the screening of deposition potentials. The optimal experimental conditions are as follows: pH = 5, HAc-NaAc as the buffer solution, the enrichment time is 180s, and the enrichment voltage is -1.0V.

[0078] (5) Electrochemical test

[0079] Electrochemical testing of Pb(II) was carried out under the above optimal experimental conditions.

[0080] The first thing to do is to conduct a baseline test: immerse the three-electrode system in a glass bottle containing 10mL of HAc-NaAc buffer solution (with a magnet in the glass bottle), start stirring, and start window one for enrichment; turn off stirring when there are 6-8s left in the enrichment time until window one is completed, and start window two for the redox process (no stirring is required for this process); after window two is finished, turn on stirring and start window three for desorption; the SWASV response curve obtained in window two can be recorded as baseline 1. Repeat the enrichment-redox-desorption process to obtain different baselines in turn, until the last baseline coincides with the previous baseline, indicating that the baseline is stable.

[0081] Then the heavy metal ion test was carried out: Ru-Co3O4 / GCE was used as the working electrode, 10 μL of 0.1 mmol / L Pb(II) solution was added to 10 mL of HAc-NaAc buffer solution, the corresponding SWASV response curve was obtained, and the response current was recorded as 0.1 mmol / L Pb(II) solution; after the window three desorption was completed, 10 μL of 0.1 mmol / L Pb(II) solution was added, and the response current was recorded as 0.2 mmol / L Pb(II) solution, and the response current value of 0.1-0.8 mmol / L Pb(II) solution was recorded in sequence; and the response current and concentration equation were obtained by linear fitting. The results are shown in the figure. Figure 3 As shown in (a), pH = 5, HAc-NaAc is a buffer solution, and its linear equation is y = 70.23x-4.96, and its slope represents the electrochemical sensitivity, which is as high as 70.23μA / μM. The theoretical detection limit is calculated according to the calculation formula LOD = 3SD / S, where SD is the standard deviation of the response current value of 0.1-0.8mmol / LPb(II) solution, and S is the sensitivity. The calculated theoretical detection limit (LOD) is 0.03μM, which is lower than 0.048μM in the National Drinking Water Hygiene Standard (GB 5749-2022).

[0082] Similarly, Co3O4 / GCE and Fe-Co3O4 / GCE were used as working electrodes, and 10 μL of 0.1 mmol / L Pb(II) solution was added to 10 mL of HAc-NaAc buffer solution to obtain the corresponding SWASV response curves. Figure 6As shown in (a) and (b), the linear equation corresponding to the Co3O4 / GCE working electrode is y=15.32x-0.97, and the linear equation corresponding to the Fe-Co3O4 / GCE working electrode is y=11.41x-1.29. It can be seen that the sensitivity of the Ru-Co3O4 nanomaterial described in the embodiment is much higher than that of the Co3O4 nanomaterial described in comparative example 1 and the Fe-Co3O4 nanomaterial described in comparative example 2.

[0083] According to the actual water sample, pH = 5, HAc-NaAc as buffer solution (V:V = 1:9) was used to prepare the test solution, and 0.1-0.8μM Pb(II) was detected on Ru-Co3O4 / GCE. The results are as follows Figure 3 As shown in (b), according to its corresponding SWASV response curve, it can be seen that the sensitivity is 68.52μA / μM, indicating that the electrode has the potential for actual water sample detection.

[0084] In addition, 0.1-0.6μM cadmium, zinc, mercury, and arsenic ions were added to four solutions containing 0.3μM Pb(II) for anti-interference experiments. Only the response current value of Pb(II) was recorded, and the response current value of impurity ions was not recorded. Taking the anti-interference test of Hg(II) as an example, the three-electrode system was immersed in a 10mL HAc-NaAc buffer solution. After the baseline test, 30μL of 0.1mmol / LPb(II) solution was added to obtain the corresponding SWASV response current curve, and the response current value was recorded as 0.30mmol / LPb(II)+0mmol / L Hg(II); then 10μL of 0.1mmol / L Hg(II) solution was added, and the response current value of Pb(II) was recorded as 0.20mmol / L Pb(II)+0.1mmol / L Hg(II), and 0.1-0.6mmol / LHg(II) was added in sequence, and the response current value of Pb(II) was recorded. The results are as follows: Figure 4 In four independent experiments, after adding 0.1-0.6mmol / L Cd(II), Hg(II), As(III), and Zn(II) solutions, the response current value of 0.3μM Pb(II) (as shown in Figure 4 (a, b, c, and d in the figure) realized the anti-interference experiment of low-concentration impurity ions, which shows that the detection of Pb(II) in water environment is not interfered by other metal ions.

[0085] Finally, the Ru-Co3O4 / GCE working electrode was subjected to ten repeated dissolution tests in a 0.3 μM Pb(II) solution, and the response curve RSD was 1.41%. Figure 4As shown in (a), ten different Ru-Co3O4 / GCEs were dissolved in 0.3μM Pb(II) solution ten times, and the response curve RSD = 4.40%. Figure 5 As shown in (b), the electrode has good stability and reproducibility.

[0086] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A Ru-Co 3 O 4 Nanomaterials, It is characterized in that The nano material is Co doped with Ru 3 O 4 Nanotubes.

2. Ru-Co according to claim 1 3 O 4 Nanomaterials, It is characterized in that The doping amount of Ru is Co 3 O 4 0.85-2.55wt%.

3. Ru-Co according to claim 1 or 2 3 O 4 Nanomaterials, It is characterized in that The nanotube has a diameter of 80-150 nm and a length of 1-100 μm.

4. A Ru-Co 3 O 4 Methods for preparing nanomaterials, It is characterized in that The steps include: S1. Add cobalt salt, urea and ammonium fluoride into water to obtain solution A; add ammonium ruthenium salt into water to obtain solution B; S2. Add solution B to solution A for hydrothermal reaction to obtain Ru-Co(OH) 2 Precursor; S3, Ru-Co(OH) 2 After the precursor is calcined, the Ru-Co 3 O 4 Nanomaterials.

5. Ru-Co according to claim 4 3 O 4 Methods for preparing nanomaterials, It is characterized in that The cobalt salt is at least one of cobalt nitrate, cobalt chloride or cobalt sulfate, and the ruthenium salt is at least one of ruthenium chloride, ruthenium nitrate or ruthenium acetate; Preferably, the molar ratio of the cobalt salt, urea and ammonium fluoride is 1:2-5:3-6; the molar ratio of the cobalt salt and ruthenium salt is 145-440:

1.

6. Ru-Co according to claim 4 or 5 3 O 4 Methods for preparing nanomaterials, It is characterized in that The hydrothermal reaction temperature is 120-150° C. and the reaction time is 4-8 hours.

7. The Ru-Co according to any one of claims 4 to 6 3 O 4 Methods for preparing nanomaterials, It is characterized in that The calcination temperature is 300-400° C. and the calcination time is 1-3 hours.

8. A Ru-Co as claimed in any one of claims 1 to 3 3 O 4 Nanomaterial or Ru-Co prepared by the preparation method according to any one of claims 4 to 7 3 O 4 Application of nanomaterials in electrochemical detection of heavy metal ions.

9. Ru-Co according to claim 8 3 O 4 Application of nanomaterials in electrochemical detection of heavy metal ions. It is characterized in that The heavy metal ion is Pb(II).

10. Ru-Co according to claim 8 or 9 3 O 4 Application of nanomaterials in electrochemical detection of heavy metal ions. It is characterized in that Specifically include: The Ru-Co 3 O 4 The nanomaterial-modified glassy carbon electrode is used as the working electrode, and the three-electrode system is formed with the reference electrode and the counter electrode for electrochemical detection. Preferably, the detection pH is 5, the enrichment time is 180s, and the enrichment voltage is -1.0V.

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