Electrochemical formaldehyde sensor electrode, method for preparing the same and electrochemical formaldehyde sensor

Abstract

The application relates to the technical field of gas sensors, and particularly discloses an electrochemical formaldehyde sensor electrode, a preparation method thereof and an electrochemical formaldehyde sensor. The electrochemical formaldehyde sensor comprises an electrochemical formaldehyde sensor electrode and a binary electrolyte; the electrochemical formaldehyde sensor electrode comprises a polytetrafluoroethylene film; the polytetrafluoroethylene film is coated with a slurry for the electrochemical formaldehyde sensor electrode; and the slurry is composed of mixed nano manganese dioxide, platinum carbon and a Nafion solution. The electrochemical formaldehyde sensor has high catalytic activity of the electrode prepared from the slurry mixed from the nano manganese dioxide, the platinum carbon and the Nafion solution, and therefore the sensor has extremely high sensitivity and excellent linearity to formaldehyde. Moreover, by regulating the proportion of the binary electrolyte, the selectivity of the electrochemical formaldehyde sensor is greatly improved, and the electrochemical formaldehyde sensor has the advantages of high sensitivity, low cost, fast response, high detection precision and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas sensors, more particularly, to an electrochemical formaldehyde sensor electrode, a preparation method thereof and an electrochemical formaldehyde sensor. BACKGROUND

[0002] Formaldehyde (HCHO) is not only a colorless and soluble irritating gas, but also a toxic substance with long incubation period. It is listed as one of the carcinogenic substances by the International Cancer Research Agency. The main sources of formaldehyde in outdoor air are the combustion of petroleum, coal and natural gas, atmospheric photochemical reactions, and the emissions of some factories producing organic resins, chemical fibers, dyes and coatings. The main sources in indoor air are building materials, furniture, various adhesives, coatings, synthetic fabrics, etc. When the human body contacts and inhales high-concentration formaldehyde gas, symptoms of discomfort will appear in a short time. Long-term exposure to high-concentration formaldehyde gas environment will cause serious harm to the human body. Therefore, it is of great significance to test and monitor formaldehyde accurately and quickly for human health and environmental protection.

[0003] As one of the most commonly used detection methods, electrochemical formaldehyde sensors have the advantages of convenient use, low cost, and can detect formaldehyde gas concentration online, real-time and quickly. However, the existing electrochemical formaldehyde gas sensors have low sensitivity, high cross-response to alcohol gas, etc. Moreover, the synthesis of the electrode of the electrochemical formaldehyde gas sensor currently uses expensive noble metals (such as iridium, gold, etc.), and the synthesis method and path are complex, which is difficult to realize large-scale batch production and application. SUMMARY

[0004] In order to improve the sensitivity, selectivity, high linearity within the measurement range, low cost and easy batch production of the sensor, the present application provides an electrochemical formaldehyde sensor electrode, a preparation method thereof and an electrochemical formaldehyde sensor.

[0005] In a first aspect, the present application provides a preparation method of an electrochemical formaldehyde sensor electrode, which adopts the following technical scheme:

[0006] The preparation method of the electrochemical formaldehyde sensor electrode comprises the following steps:

[0007] (1) After stirring and mixing potassium permanganate, deionized water and anhydrous ethanol, stirring reaction is carried out at 130-150℃ for 6-8h to obtain a reaction solution; the reaction solution is centrifuged, the lower precipitate is collected, and washed with water to obtain a precursor;

[0008] The precursor is dried at 60-80℃ for 4-6h to obtain a solid powder of the precursor;

[0009] The solid powder of the precursor is calcined at 400-500℃ for 1-3h to obtain nano manganese dioxide;

[0010] (2) mixing the nano-manganese dioxide, platinum carbon and Nafion solution, and grinding at a speed of 300-400 r / min for 0.5-1 h to obtain a ground slurry;

[0011] (3) coating the ground slurry on a polytetrafluoroethylene film and drying at 60-80℃ for 0.5-1 h to obtain an electrochemical formaldehyde sensor electrode.

[0012] By using the above technical solution, the nano-manganese dioxide, platinum carbon and Nafion solution are compounded into a slurry according to the above weight ratio, and then coated on the electrochemical formaldehyde sensor electrode, which not only has a high decomposition catalytic effect on formaldehyde, but also has a high catalytic activity of platinum carbon, and the perfluoro ion sulfonic acid resin can effectively promote the flow of ions and the transfer of electric charges, so that the sensor assembled by coating the above slurry has a high response sensitivity to formaldehyde.

[0013] Meanwhile, the nano-manganese dioxide prepared by the hydrothermal method is in a spherical or near-spherical morphology with a particle size distribution of 30-50 nm, and has a large specific surface area, which is beneficial to the aggregation and transmission of electric charges on the surface of the spherical powder, thus improving the catalytic activity of the electrode coated with the slurry and the gas reaction, and the sensor assembled by using the electrode has a higher response sensitivity to formaldehyde.

[0014] Preferably, in the step (1), the mass ratio of potassium permanganate, deionized water and anhydrous ethanol is 1:(20-30):(30-50).

[0015] Preferably, in the step (1), the speed of centrifugation is 8000-10000 r / min, and the time is 4-8 min.

[0016] Preferably, the particle size of the platinum carbon is 100-400 nm.

[0017] The platinum carbon is composed of platinum and carbon in a mass ratio of 4:1.

[0018] Preferably, the mass ratio of the nano-manganese dioxide, platinum carbon and Nafion solution is (0.1-0.3):1:(0.1-0.25).

[0019] Preferably, the grinding is ball milling, and the speed of the ball milling is 300-400 r / min.

[0020] Preferably, the coating method of the slurry includes any one of rolling, spraying, screen printing and molding.

[0021] In the second aspect, the application provides an electrochemical formaldehyde sensor, which uses the following technical solution:

[0022] An electrochemical formaldehyde sensor comprises the above-mentioned electrochemical formaldehyde sensor electrode and a binary electrolyte.

[0023] Preferably, the binary electrolyte comprises any two of sulfuric acid, phosphoric acid, hydrochloric acid, lithium chloride and trisodium citrate.

[0024] Preferably, the molar concentration of the sulfuric acid is 3-6 mol / L, the molar concentration of the phosphoric acid is 2-7 mol / L, the molar concentration of the hydrochloric acid is 0.5-8 mol / L, the molar concentration of the lithium chloride is 0.5-9 mol / L, and the molar concentration of the trisodium citrate is 0.2-4 mol / L.

[0025] Preferably, the binary electrolyte is composed of lithium chloride and trisodium citrate.

[0026] By adopting the above technical solution, since the electrochemical formaldehyde sensor electrode has high catalytic reactivity to formaldehyde, the electrochemical formaldehyde sensor assembled by using the electrode and the binary electrolyte has high sensitivity to formaldehyde gas and excellent linearity within the measurement range.

[0027] Meanwhile, by regulating the composition of the binary electrolyte of the electrochemical formaldehyde sensor, high selectivity of the electrochemical formaldehyde sensor is achieved, and the influence of environmental interference gas on the formaldehyde sensor is greatly reduced, thereby improving the detection accuracy. In particular, the binary lithium chloride and trisodium citrate are selected as the binary electrode liquid, which does not affect the response sensitivity of formaldehyde gas entering the sensor, and at the same time, the transmission rate of cross interference gas such as alcohol is inhibited, thereby improving the selectivity of the sensor.

[0028] In summary, the present application has the following beneficial effects:

[0029] 1. Since the present application adopts nanometer manganese dioxide mixed and dispersed with platinum carbon and Nafion solution to prepare a slurry coated on an electrode, which has high catalytic activity to formaldehyde, the electrochemical formaldehyde gas sensor electrode assembled by using the electrode has high sensitivity to formaldehyde and excellent linearity within the measurement range.

[0030] 2. The nanometer manganese dioxide prepared by the simple hydrothermal method of the present application has a spherical or near-spherical morphology and a particle size distribution of 30-50 nm, and has a large specific surface area, which is beneficial to the aggregation and transmission of electric charges on the surface of the spherical powder, thereby improving the catalytic activity of the electrode coated with the slurry to formaldehyde gas.

[0031] 3. The electrochemical formaldehyde sensor of the present application realizes high selectivity of the electrochemical formaldehyde sensor by regulating the composition of the binary electrolyte, greatly reduces the influence of environmental interference gas on the formaldehyde sensor, and improves the detection accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Scanning electron microscope image of the nanoscale manganese dioxide prepared in Preparation Example 1;

[0033] Figure 2 Response recovery curve of Examples 1-5 in 0-1 ppm formaldehyde gas;

[0034] Figure 3 Stepwise aeration and linear fitting curve of Example 5 in 0-10 ppm formaldehyde gas;

[0035] Figure 4 Cyclic adsorption and desorption curve of Example 5 in 0-10 ppm formaldehyde gas. DETAILED DESCRIPTION

[0036] The present application is further described in detail below with reference to the accompanying drawings and examples.

[0037] Preparation Example 1

[0038] A nanoscale manganese dioxide, comprising the following steps:

[0039] S1: stirring and mixing 15 g of potassium permanganate, 100 mL of deionized water and 18 g of anhydrous ethanol, then stirring and reacting at 150°C for 6 h to obtain a reaction solution; centrifuging the reaction solution at a speed of 900 r / min for 6 min, collecting the lower precipitate, and washing with water to obtain a precursor;

[0040] S2: drying the precursor at 80°C for 6 h to obtain a solid powder of the precursor;

[0041] S3: calcining the solid powder of the precursor at 450°C for 1.5 h to obtain 4.06 g of nanoscale manganese dioxide.

[0042] It can be seen that the nanoscale manganese dioxide prepared in Preparation Example 1 has a spherical or near-spherical morphology with a particle size distribution of 30-50 nm and a large specific surface area, thereby facilitating the aggregation and transmission of charges on the surface of the spherical powder and improving the catalytic activity in the reaction with formaldehyde gas. Figure 1 Performance test

[0043] The electrochemical formaldehyde sensor prepared in the examples was subjected to gas aeration test in 1 ppm formaldehyde gas and cross-response test in different gases, and the test steps were as follows:

[0044]

[0045] ​(1) Gas aeration test in 1ppm formaldehyde gas: under room temperature environment, the aged electrochemical formaldehyde sensor of the embodiment is subjected to gas aeration test in 1ppm formaldehyde gas, and the output current of the test circuit board before and after aeration is tested respectively, so as to obtain the gas sensitivity performance of the sensor;

[0046] (2) Cross-response test in different gases: under room temperature environment, the aged electrochemical formaldehyde sensor of the embodiment is subjected to aeration test in different cross gases, and the output current of the test circuit board before and after aeration is tested respectively, so as to obtain the gas sensitivity performance of the sensor;

[0047] The cross gases for testing the electrochemical formaldehyde sensor in the embodiment are: 50ppm ethanol gas, 50ppm carbon monoxide gas, 50ppm hydrogen gas and 50ppm methane gas.

[0048] Embodiment 1

[0049] An electrochemical formaldehyde sensor includes a plastic shell, and a working electrode, a reference electrode and a counter electrode are assembled in the plastic shell. The electrodes are filled with absorbent cotton between the electrodes, and an electrolyte is filled in as an electronic flow medium. The working electrode, the reference electrode and the counter electrode are connected to a test circuit board through platinum wires and pins to realize output of a current signal.

[0050] An upper cover for gas inlet is arranged on the plastic shell. After the working electrode, the reference electrode and the counter electrode are installed in the shell, 300μL of 4M sulfuric acid electrolyte is added, the shell is sealed after the gas inlet upper cover is assembled. Finally, the working electrode and the counter electrode are short-circuited for aging for 5 days, and the aged electrochemical formaldehyde sensor is obtained.

[0051] In the embodiment, the materials of the working electrode, the reference electrode and the counter electrode are all electrochemical formaldehyde sensor electrodes, wherein the working electrode and the reference electrode are both φ16mm round sheets, and the counter electrode is a φ16*6mm round ring.

[0052] The electrochemical formaldehyde sensor electrode includes a polytetrafluoroethylene film, and the polytetrafluoroethylene film is coated with a slurry for electrochemical formaldehyde sensor electrodes.

[0053] The slurry for electrochemical formaldehyde sensor electrodes is composed of 1.0g of nanometer manganese dioxide, 5.0g of platinum carbon and 1.0g of Nafion solution.

[0054] In the embodiment, the nanometer manganese dioxide is commercial nanometer manganese dioxide, and the particle size is 30-60nm.

[0055] The platinum carbon is composed of platinum and carbon in a mass ratio of 4:1, and the particle size is 300nm.

[0056] The mass percentage of perfluorosulfonic acid resin in the Nafion solution is 10%.

[0057] The preparation method of the above-mentioned electrochemical formaldehyde sensor electrode comprises the following steps:

[0058] (1) After mixing the nanometer manganese dioxide, platinum carbon and Nafion solution, a slurry for the electrochemical formaldehyde sensor electrode is obtained; after mixing and ball milling the above-mentioned slurry at a rotation speed of 300 r / min for 0.5 h, a ground slurry is obtained.

[0059] (2) The ground slurry is screen printed on a polytetrafluoroethylene film, and dried at 60℃ for 0.5 h, thereby obtaining the electrochemical formaldehyde sensor electrode.

[0060] Comparative Example 1

[0061] An electrochemical formaldehyde sensor, which is different from Example 1 in that the slurry for the electrochemical formaldehyde sensor electrode is composed of 5.0 g of platinum carbon and 0.9 g of Nafion solution.

[0062] The platinum carbon is composed of platinum and carbon at a mass ratio of 4:1, and the particle size is 300 nm;

[0063] The mass percentage of perfluorosulfonic acid resin in the Nafion solution is 10%.

[0064] Comparative Example 2

[0065] An electrochemical formaldehyde sensor, which is different from Example 1 in that the slurry for the electrochemical formaldehyde sensor electrode is composed of 1.6 g of commercial nanometer manganese dioxide, 5.0 g of platinum carbon and 1.2 g of Nafion solution.

[0066] Comparative Example 3

[0067] An electrochemical formaldehyde sensor, which is different from Example 1 in that the slurry for the electrochemical formaldehyde sensor electrode is composed of 1.1 g of commercial nanometer manganese dioxide, 5.0 g of platinum carbon and 0.4 g of Nafion solution.

[0068] Comparative Example 4

[0069] An electrochemical formaldehyde sensor, which is different from Example 1 in that the slurry for the electrochemical formaldehyde sensor electrode is composed of 1.0 g of commercial nanometer manganese dioxide, 5.0 g of platinum carbon and 1.4 g of Nafion solution.

[0070] The electrochemical formaldehyde sensors prepared in Example 1 and Comparative Examples 1-4 are subjected to gas aeration test in 1 ppm formaldehyde gas, and the test results are shown in Table 1.

[0071] Table 1: Comparison of response sensitivity of electrochemical formaldehyde sensor of Examples 1-5 to 1 ppm formaldehyde gas

[0072]

[0073] From the data analysis of Table 1, it can be seen that the sensitivity of the comparative example 1 sensor to formaldehyde is low, and the sensitivity of the Example 1 sensor to formaldehyde is greatly improved. However, as the amount of nano-manganese dioxide added to the sensor electrode is further increased, the response sensitivity of the comparative example 2 sensor to formaldehyde gas is slightly reduced. The possible reason is that the introduction of excessive nano-manganese dioxide inhibits the catalytic activity of platinum carbon, resulting in a decrease in response sensitivity.

[0074] From Table 1, it can be seen that the response sensitivity of the comparative example 3 sensor to formaldehyde gas decreases as the amount of perfluoro ion sulfonic acid resin decreases. The possible reason is that the oxidation-reduction reaction of formaldehyde gas entering the sensor requires perfluoro ion sulfonic acid resin to promote ion flow and charge transfer. When the amount of perfluoro sulfonic acid resin loaded on the sensor electrode is insufficient to meet the normal output of the signal, the response sensitivity is reduced. Similarly, when the amount of perfluoro ion sulfonic acid resin of the comparative example 4 sensor is relatively large, the response sensitivity of the sensor to formaldehyde gas is not further improved. At this time, the main factor affecting the response sensitivity of the sensor is the catalytic activity of the catalyst, and the effect of the perfluoro sulfonic acid resin is low.

[0075] Therefore, in the electrochemical formaldehyde sensor of the present application, when the slurry coated on the surface of the electrochemical formaldehyde sensor electrode is composed of nano-manganese dioxide, platinum carbon and Nafion solution at a weight ratio of (0.1-0.3):1:(0.1-0.25), the response sensitivity of the electrochemical formaldehyde sensor can be improved.

[0076] Example 2

[0077] An electrochemical formaldehyde sensor, which differs from Example 1 in that the nano-manganese dioxide in the electrochemical formaldehyde sensor electrode is the nano-manganese dioxide prepared in Preparation Example 1, which has a spherical or near-spherical morphology with a particle size distribution of 30-50 nm; and the platinum carbon is composed of platinum and carbon at a mass ratio of 4:1, and has a particle size of 350 nm.

[0078] Example 3

[0079] An electrochemical formaldehyde sensor, which differs from Example 2 in that the electrolyte is composed of 150 μL of 4M sulfuric acid and 150 μL of 1.1M lithium chloride.

[0080] Example 4

[0081] An electrochemical formaldehyde sensor, which is different from Example 2 in that the electrolyte is composed of 150 μL of 4 M sulfuric acid and 150 μL of 2.7 M phosphoric acid.

[0082] Example 5

[0083] An electrochemical formaldehyde sensor, which is different from Example 2 in that the electrolyte is composed of 150 μL of 1.1 M lithium chloride and 150 μL of 2.8 M trisodium citrate.

[0084] The response recovery curves of the electrochemical formaldehyde sensors prepared in Examples 1, 2-5 in 1 ppm formaldehyde gas are shown in Figure 2 It can be seen from Figure 2 that the sensor prepared in Example 1, in which commercial nanometer manganese dioxide is added to the sensor electrode, has a lower response signal to formaldehyde gas, and the desorption of formaldehyde gas after the end of aeration is also slower. The sensor prepared in Example 2, in which self-made nanometer manganese dioxide is added to the sensor electrode, has an improved response sensitivity to formaldehyde gas, and meets the requirement of signal output, but still has the problem of too long response and recovery time.

[0085] However, it can be seen from the response recovery curves of Examples 3-5 that when the sensor electrode is maintained to be the same component, by adjusting the electrolyte to be a binary component, it can be seen that the response signal of the sensor to formaldehyde is further improved, and the response and recovery rates are also improved accordingly.

[0086] The reason for this is that in the process of gas entering the electrochemical sensor for reaction, the electrolyte solution has a decisive influence on ion conduction. After different gases enter the sensor, the unit sensitivity signal of the reaction is different, and the conduction rate is also greatly different under different electrolyte solutions. Therefore, the selection of lithium chloride and trisodium citrate as a binary electrolyte does not affect the response sensitivity of formaldehyde gas entering the sensor, while inhibiting the transmission rate of cross-interference gases such as alcohols, thereby improving the selectivity of the sensor.

[0087] The electrochemical formaldehyde sensors prepared in Examples 1-5 were subjected to cross-response tests in different gases, and the test results are shown in Table 2.

[0088] Table 2: Cross-response test control table of the electrochemical formaldehyde sensors of Examples 1-5

[0089]

[0090] It can be seen from Figure 3It can be seen that the formaldehyde sensor of Example 5 has a response to formaldehyde gas within a concentration range of 0-10 ppm and a response time that remains short as the formaldehyde gas concentration increases, which represents excellent response and recovery characteristics. The sensor still has a stable current output of 1500 nA when tested at a formaldehyde gas concentration of 0.5 ppm, which represents an excellent lower detection limit. At the same time, Figure 3 The linear fitting curve of the response sensitivity of the formaldehyde sensor of Example 5 at different formaldehyde gas concentrations is shown in the drawing in FIG. 7: y = 2993.52X - 21.42, where X is the formaldehyde gas concentration, and y is the response sensitivity at the corresponding gas concentration. The response sensitivity of the sensor at different formaldehyde gas concentrations is well linearly related to the output sensitivity value, as shown in the drawing in FIG. 7. Figure 3 2 R is the linear fitting coefficient, which is a statistical quantity for measuring the goodness of the linear regression model fitting data, R 2 = regression sum of squares / total sum of squares, the value of R2 is between 0 and 1, and the closer the value is to 1, the better the fitting degree of the model to the data; the linear fitting coefficient R 2 of Example 5 is 0.997, which indicates that the formaldehyde sensor has an extremely low lower detection limit and excellent linearity within the measurement range.

[0091] Figure 4 The cyclic adsorption and desorption curve of the formaldehyde sensor prepared in Example 5 in 10 ppm formaldehyde gas is shown in FIG. 8. It can be seen from the figure that the sensor has a better response sensitivity to formaldehyde gas in each cycle test period, the response and desorption performance is maintained in a stable state, which represents the characteristics of high concentration and low poisoning, and the consistency is excellent.

[0092] In summary, in combination with the data of each example, it can be seen that:

[0093] The response sensitivity of the sensor prepared in Example 1 with platinum carbon as the electrode is low to formaldehyde gas, which cannot output an effective signal to achieve the purpose of detecting formaldehyde gas;

[0094] The sensor prepared by adding nano manganese dioxide powder to the catalyst electrode of Example 2 greatly improves the response sensitivity of the sensor to formaldehyde gas, but the cross-response sensitivity to gases such as ethanol and carbon monoxide is also large, which is easy to cause false alarms in actual application environments;

[0095] The binary electrolyte components used in the sensors of Examples 3 and 4 further improve the response sensitivity of the sensor to formaldehyde gas, and the cross-response sensitivity to ethanol and carbon monoxide is also reduced, but it still cannot meet the demand of actual use, and there is still a risk of false alarms.

[0096] ​The sensor of embodiment 5 adjusts the components of binary electrolyte, and has the greatest sensitivity to formaldehyde gas, and can improve the strength of signal output. Therefore, the use of lithium chloride with a molar concentration of 0.5-9 mol / L and trisodium citrate with a molar concentration of 0.2-4 mol / L greatly reduces the cross-interference signal of the sensor to common gases such as ethanol and carbon monoxide, and is an excellent electrochemical formaldehyde sensor.

[0097] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments according to the needs after reading the specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An electrochemical formaldehyde sensor, characterized by, The electrode comprises an electrochemical formaldehyde sensor electrode and a binary electrolyte; the electrochemical formaldehyde sensor electrode comprises a polytetrafluoroethylene film; the polytetrafluoroethylene film is coated with a slurry for the electrochemical formaldehyde sensor electrode; The slurry for the electrochemical formaldehyde sensor electrode is composed of nano-manganese dioxide, platinum carbon and Nafion solution in a weight ratio of (0.1-0.3):1:(0.1-0.25). The nano-manganese dioxide is spherical or near-spherical in morphology with a particle size distribution of 30-50 nm. The binary electrolyte is composed of lithium chloride and trisodium citrate. The molar concentration of lithium chloride is 0.5-9 mol / L, and the molar concentration of trisodium citrate is 0.2-4 mol / L.

2. A method of preparing an electrochemical formaldehyde sensor electrode, characterized by, The method comprises the following steps: (1) mixing potassium permanganate, deionized water and anhydrous ethanol by stirring, and then stirring and reacting at 130-150℃ for 6-8 h to obtain a reaction solution; centrifuging the reaction solution, collecting the lower precipitate, and washing with water to obtain a precursor; drying the precursor at 60-80℃ for 4-6 h to obtain a solid powder of the precursor; calcining the solid powder of the precursor at 400-500℃ for 1-3 h to obtain nano-manganese dioxide; the nano-manganese dioxide is spherical or near-spherical in morphology with a particle size distribution of 30-50 nm; (2) mixing nano-manganese dioxide, platinum carbon and Nafion solution in a weight ratio of (0.1-0.3):1:(0.1-0.25) to obtain a slurry for the electrochemical formaldehyde sensor electrode; mixing and grinding the slurry at a speed of 300-400 r / min for 0.5-1 h to obtain a ground slurry; (3) coating the ground slurry on a polytetrafluoroethylene film, and drying at 60-80℃ for 0.5-1 h to obtain the electrochemical formaldehyde sensor electrode.

3. The method for preparing the electrochemical formaldehyde sensor electrode according to claim 2, characterized in that, In the step (1), the mass ratio of potassium permanganate, deionized water and anhydrous ethanol is 1:(20-30):(30-50).

4. The method for preparing the electrochemical formaldehyde sensor electrode according to claim 2, characterized in that, In the step (1), the centrifugation speed is 8000-10000 r / min, and the time is 4-8 min.

5. The method for preparing the electrochemical formaldehyde sensor electrode according to claim 2, characterized in that, The particle size of the platinum carbon is 100-400 nm; the platinum carbon is composed of platinum and carbon in a mass ratio of 4:

1.

6. The method for preparing the electrochemical formaldehyde sensor electrode according to claim 2, characterized in that, The grinding is ball milling, and the ball milling speed is 300-400 r / min.

7. An electrochemical formaldehyde sensor electrode, characterized by The electrochemical formaldehyde sensor electrode is prepared by the method of any one of claims 2-6.

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