Preparation method of carbon monoxide electrochemical sensor electrode

Abstract

The invention provides a preparation method of a carbon monoxide electrochemical sensor electrode, the electrode provides a reaction place for a solid-liquid-gas three-phase reaction, and the preparation method comprises the following steps: stirring noble metal powder, a conductive material I, a conductive material II, a hydrophobic substance material, a hydrophilic substance material and an adhesive according to a certain proportion to prepare slurry with a certain solid content; and coating the slurry on a microporous substrate material by adopting a silk screen, and drying to form the carbon monoxide electrochemical sensor electrode. Compared with a traditional method, the electrode prepared through the preparation method is lower in cost, and on the basis that the cost is reduced, the sensitivity is greatly improved, and the response time is greatly shortened.

Description

Technical Field

[0001] The invention relates to the field of electrode preparation, and in particular to a method for preparing a carbon monoxide electrochemical sensor electrode. Background Art

[0002] Electrochemical carbon monoxide sensors are widely used in petrochemical, environmental protection and other fields due to their advantages such as low power consumption and good linearity within the measuring range. The core of carbon monoxide sensors lies in the preparation and selection of electrodes and shells. However, since the main component of the electrode sheet is platinum, the platinum catalyst has a high response to carbon monoxide, but it has a certain response to almost all toxic gases, which makes the method of processing platinum catalysts a major difficulty in the preparation of carbon monoxide sensors. At present, the biggest problem of carbon monoxide sensors is the cross-interference problem. Hydrogen is one of the gases with the greatest interference to carbon monoxide sensors. On the one hand, the sensor's response to hydrogen is often greater than 50%, or even greater than 100%, which greatly increases the potential danger of false alarms. On the other hand, hydrogen cannot be directly removed by simply adding filters such as carbon cloth for adsorption or producing redox reactions. The only way is to prepare a working electrode with good selectivity. Therefore, preparing a working electrode with good selectivity is the core work of carbon monoxide sensors.

[0003] The electrodes of the currently prepared carbon monoxide electrochemical sensors contain high amounts of precious metals, are high in cost, have low sensitivity, and have long response times. Summary of the invention

[0004] In view of the problems existing in the prior art, a method for preparing a carbon monoxide electrochemical sensor electrode is provided, which makes the electrode both hydrophilic and hydrophobic, realizes solid-liquid-gas three-phase reaction on the electrode surface, provides raw materials and electron transmission paths for electrode catalytic reaction, and solves the problems of low sensitivity, long response time, and reduces the amount of precious metal materials.

[0005] The technical solution adopted by the present invention is as follows: a method for preparing a carbon monoxide electrochemical sensor electrode, wherein the electrode provides a reaction site for a solid-liquid-gas three-phase reaction, comprising:

[0006] Precious metal powder, conductive material 1, conductive material 2, hydrophobic material, hydrophilic material, and adhesive are mixed in a certain proportion to prepare a slurry with a certain solid content;

[0007] The slurry is coated on a microporous base material by using a screen and dried to form a carbon monoxide electrochemical sensor electrode.

[0008] As a preferred solution, the mass percentages of precious metal powder, conductive material one, conductive material two, hydrophobic material, hydrophilic material and adhesive in the slurry are 10-50%, 0.5-15%, 5-60%, 1-10%, 0.5-3% and 1-8% respectively.

[0009] As a preferred solution, the solid content of the slurry is 0.3-0.8%.

[0010] As a preferred solution, two PTFE microporous membranes are arranged on the microporous base material.

[0011] As a preferred solution, a 100-400 mesh screen is used for coating.

[0012] As a preferred embodiment, the drying process includes: drying at 70-110° C. for 1-12 hours, and drying at 120-230° C. for 1-12 hours.

[0013] As a preferred solution, the noble metal powder is platinum black or nano gold powder.

[0014] As a preferred solution, the first conductive material is carbon nanotubes, and the second conductive material is carbon nanopowder.

[0015] As a preferred solution, the hydrophobic material is nafion solution, and the hydrophilic material is PTFE powder.

[0016] As a preferred solution, the adhesive is PVDF powder.

[0017] Compared with the prior art, the above technical scheme has the following beneficial effects: the precious metal mass content of the electrode prepared by the preparation method proposed in the present invention is ≤50%, while the existing one is >90%; the sensitivity is 95-105nA / ppmCO, while the existing one is 60-75nA / ppm; the response time is within 10s, while the existing sensor response time is within 30s; the linearity R 2 >0.99; repeatability ≤3%. On the basis of reducing costs, the sensitivity, response time and other performances are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of a method for preparing a carbon monoxide electrochemical sensor electrode proposed by the present invention. DETAILED DESCRIPTION

[0019] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar modules or modules with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be construed as limitations on the present application. On the contrary, the embodiments of the present application include all changes, modifications and equivalents that fall within the spirit and connotation of the appended claims.

[0020] In order to solve the problems of high content of precious metal materials, low sensitivity and long response time, the present invention proposes a method for preparing a carbon monoxide electrochemical sensor electrode, please refer to Figure 1 , the specific process is as follows:

[0021] Step 1: Precious metal powder, conductive material 1, conductive material 2, hydrophobic material, hydrophilic material and adhesive are stirred in a certain proportion to prepare a slurry with a certain solid content.

[0022] In this embodiment, in the prepared slurry, the mass percentages of precious metal powder, conductive material one, conductive material two, hydrophobic material, hydrophilic material, and adhesive are 10-50%, 0.5-15%, 5-60%, 1-10%, 0.5-3%, and 1-8%, respectively.

[0023] When preparing the slurry, NMP and pineol are used as dispersants, and after dispersion, continuous stirring is performed to obtain a slurry with a solid content of 0.3-0.8%.

[0024] Step 2: Use a screen to coat the slurry on a microporous substrate material, and dry it to form a carbon monoxide electrochemical sensor electrode.

[0025] In this embodiment, two PTFE microporous membranes are arranged on the microporous base material. During coating, a 100-400 mesh screen is used for coating.

[0026] After coating, the desired electrode can be formed by drying. In this embodiment, a specific drying process is also provided: drying at 70-110° C. for 1-12 hours, and drying at 120-230° C. for 1-12 hours.

[0027] Furthermore, in the slurry preparation process, the precious metal powder can be made of platinum black or nano gold powder; the conductive material

[0028] Carbon nanotubes can be used; the conductive material can be carbon nanopowder; the adhesive can be PVDF powder; the hydrophobic material is nafion solution, and the hydrophilic material is PTFE powder. The electrode preparation cost can be greatly reduced by selecting and distributing the slurry materials.

[0029] The electrode prepared by the above preparation method has a sensitivity of 95-105nA / ppm, a response time of less than 10s, and an electrode cost of less than 6 yuan. Compared with the traditional preparation method, the cost is reduced and the performance is greatly improved.

[0030] In order to verify the effectiveness of the present invention, the experiment was conducted by controlling a single variable in this embodiment, wherein the mass percentages of precious metal powder, conductive material 1, conductive material 2, hydrophobic material, hydrophilic material, and adhesive were 10-50%, 0.5-15%, 5-60%, 1-10%, 0.5-3%, and 1-8%, respectively. The solid content of the slurry was 0.3-0.8%. The coated screen was 100-400 mesh. Drying process: Dry at 70-110°C for 1-12 hours, and at 120-230°C for 1-12 hours. The specific test data are as follows:

[0031] (1) Precious metal powder (platinum black)

[0032]

[0033] Appropriately adding metal materials can effectively increase the sensitivity of carbon monoxide electrochemical sensors.

[0034] (2) Hydrophilic materials

[0035]

[0036]

[0037] Hydrophilic materials provide protons for the reaction, increasing the reaction rate and efficiency and improving sensitivity.

[0038] (3) Adhesive

[0039]

[0040] The binder increases the strength of the electrode and prevents it from falling off.

[0041] (4) Conductive material 1 (CNT)

[0042]

[0043] Carbon nanotubes (CNTs) can effectively improve the conductivity of electrodes, increase porosity, and shorten response time.

[0044] (5) Hydrophobic materials

[0045]

[0046] The function of PTFE powder is to make the working electrode partially hydrophobic to form a solid-liquid-gas three-box reaction, thereby improving sensitivity and stabilizing the zero-point voltage. The optimal ratio is 5%.

[0047] (6) Conductive material 2 (carbon nanopowder)

[0048]

[0049] The role of carbon nanopowder is to increase the conductivity and reduce the amount of carbon nanotubes used.

[0050] (7) Solid content

[0051] Solid content (%) 0.3 0.4 0.5 0.6 0.7 0.8 Sensitivity (nA / ppm) 45-65 60-85 90-105 90-105 90-105 60-70 Response time(s) 15-35 ＜10 ＜10 ＜10 ＜10 ＜10 <![CDATA[R 2 ]]> 0.97 0.99 0.99 0.99 0.99 0.99 Repeatability (%) ≤3 ≤3 ≤3 ≤3 ≤3 ≤3

[0052] The example uses NPM as the solvent of the electrode slurry. Its main function is to wet the material to make the electrode slurry and print it evenly on the substrate.

[0053] (8) Silk screen

[0054] Screen mesh 100 200 300 400 Sensitivity (nA / ppm) 65-95 90-105 90-105 80-100 Response time(s) ＜10 ＜10 ＜10 ＜10 <![CDATA[R 2 ]]> 0.99 0.99 0.99 0.99 Repeatability (%) ≤3 ≤3 ≤3 ≤3

[0055] The size of the screen determines the sensitivity.

[0056] (9) Drying temperature

[0057] T1(℃) 70 80 90 110 Sensitivity (nA / ppm) 75-105 90-105 90-105 90-105 Response time(s) 10-20 ＜10 ＜10 ＜10 <![CDATA[R 2 ]]> 0.96 0.99 0.99 0.99 Repeatability (%) ≤3 ≤3 ≤3 ≤3

[0058] The electrode slurry is hard brushed onto the substrate and dried in two stages, namely T1 and T2, which can effectively reduce the cracking of the catalyst layer and completely evaporate the solvent.

[0059]

[0060]

[0061] The best drying temperature for the first stage is 70-110°C, and the best drying temperature for the second stage is 120-230°C. The drying time must be the same.

[0062] (10) Drying time

[0063]

[0064] The two-stage drying is carried out at the specified temperature in (9), and the sensitivity increases with time.

[0065] Example 1

[0066] This embodiment proposes a method for preparing a carbon monoxide electrochemical sensor electrode, wherein the electrode provides a reaction site for a solid-liquid-gas three-phase reaction, including:

[0067] Precious metal powder, conductive material 1, conductive material 2, hydrophobic material, hydrophilic material, and adhesive are mixed in a certain proportion to prepare a slurry with a certain solid content;

[0068] The slurry is coated on a microporous base material by using a screen and dried to form a carbon monoxide electrochemical sensor electrode.

[0069] Example 2

[0070] Based on Example 1, the mass percentages of precious metal powder, conductive material one, conductive material two, hydrophobic material, hydrophilic material and adhesive in the slurry of this example are 10-50%, 0.5-15%, 5-60%, 1-10%, 0.5-3% and 1-8% respectively.

[0071] Example 3

[0072] Based on Example 2, the solid content of the slurry in this example is 0.3-0.8%.

[0073] Example 4

[0074] On the basis of Example 3, in this example, two PTFE microporous membranes are arranged on the microporous base material.

[0075] Example 5

[0076] On the basis of Example 4, a 100-400 mesh screen is used for coating in this example.

[0077] Example 6

[0078] On the basis of Example 5, the drying process in this example includes: drying at 70-110° C. for 1-12 hours, and drying at 120-230° C. for 1-12 hours.

[0079] Example 7

[0080] On the basis of Example 6, the precious metal powder in this example is platinum black or nano gold powder.

[0081] Example 8

[0082] On the basis of Example 7, in this example, the first conductive material is carbon nanotubes, and the second conductive material is carbon nanopowder.

[0083] Example 9

[0084] On the basis of Example 8, the hydrophobic material in this example is nafion solution, and the hydrophilic material is PTFE powder.

[0085] Example 10

[0086] On the basis of Example 9, the adhesive in this example is PVDF powder.

[0087] The present invention can be better realized through Examples 1 to 10.

[0088] For those skilled in the art, the specific meanings of the above terms in the present invention can be understood in specific situations; the drawings in the embodiments are used to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0089] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for preparing a carbon monoxide electrochemical sensor electrode, characterized in that: The electrodes provide a reaction site for solid-liquid-gas three-phase reaction, including: Precious metal powder, conductive material 1, conductive material 2, hydrophobic material, hydrophilic material, and adhesive are mixed in a certain proportion to prepare a slurry with a certain solid content; The slurry is coated on a microporous base material by using a screen and dried to form a carbon monoxide electrochemical sensor electrode.

2. The method for preparing a carbon monoxide electrochemical sensor electrode according to claim 1, characterized in that: The mass percentages of precious metal powder, conductive material 1, conductive material 2, hydrophobic material, hydrophilic material and adhesive in the slurry are 10-50%, 0.5-15%, 5-60%, 1-10%, 0.5-3% and 1-8% respectively.

3. The method for preparing a carbon monoxide electrochemical sensor electrode according to claim 1, characterized in that: The solid content of the slurry is 0.3-0.8%.

4. The method for preparing a carbon monoxide electrochemical sensor electrode according to claim 1, characterized in that: Two PTFE microporous membranes are arranged on the microporous base material.

5. The method for preparing a carbon monoxide electrochemical sensor electrode according to claim 1, characterized in that: Use 100-400 mesh screen for coating.

6. The method for preparing a carbon monoxide electrochemical sensor electrode according to claim 1, characterized in that: The drying process comprises: drying at 70-110° C. for 1-12 hours, and drying at 120-230° C. for 1-12 hours.

7. The method for preparing a carbon monoxide electrochemical sensor electrode according to claim 1, characterized in that: The noble metal powder is platinum black or nano gold powder.

8. The method for preparing a carbon monoxide electrochemical sensor electrode according to claim 1, characterized in that: The conductive material 1 is carbon nanotube, and the conductive material 2 is carbon nanopowder.

9. The method for preparing a carbon monoxide electrochemical sensor electrode according to claim 1, characterized in that: The hydrophobic material is nafion solution, and the hydrophilic material is PTFE powder.

10. The method for preparing a carbon monoxide electrochemical sensor electrode according to claim 1, characterized in that: The adhesive is PVDF powder.

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