Method for preparing WC / Pt / C catalyst based on magnetron sputtering method and application of WC / Pt / C catalyst
By using magnetron sputtering method to prepare WC/Pt/C catalysts in fuel cell catalysts, the problems of CO poisoning and sulfonic acid group toxicity are solved, and the activity of the catalyst and the polarization performance of the fuel cell are improved.
Patent Information
- Application Number
- CN202411344746.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-25
- Publication Date
- 2024-12-31
AI Technical Summary
In fuel cells, traditional Pt/C catalysts are prone to deterioration in performance due to CO poisoning and sulfonic acid group toxicity, making it difficult to maintain high efficiency and durability.
The WC/Pt/C catalyst is formed on the carbon support by magnetron sputtering method. By sputtering the tungsten carbide particle layer outside the platinum nanoparticle layer, the CO adsorption and contact between sulfonic acid groups and platinum particles are reduced, and the activity of the catalyst is improved. and durability.
Effectively prevent CO poisoning, reduce the toxicity of sulfonic acid groups, and improve the activity of the catalyst and the polarization performance of the fuel cell.
Smart Images
Figure CN119230856A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of fuel cell catalysts, and in particular to a method for preparing a WC / Pt / C catalyst based on a magnetron sputtering method and an application thereof. Background Art
[0002] In fuel cell technology, the performance of the catalyst plays a decisive role in the overall efficiency and durability of the battery. Traditional catalysts use carbon carriers to load platinum particles to form Pt / C catalysts, which have good catalytic activity. However, during the operation of the fuel cell, a small amount of CO gas is usually attached to the hydrogen fuel. When the hydrogen oxidation reaction occurs at the anode, the CO molecules will be strongly adsorbed on the active sites of the catalyst, causing CO poisoning of the catalyst; on the other hand, the sulfonic acid group will interact with platinum at high electrical density, and it is easy to adsorb on the surface of the platinum particles to poison, affecting the activity of the catalyst and causing reduced fuel cell performance.
[0003] Based on this, in order to improve the performance of the catalyst, the present invention proposes a method for preparing a WC / Pt / C catalyst based on magnetron sputtering and its application. Summary of the invention
[0004] The purpose of the present invention is to provide a method for preparing a WC / Pt / C catalyst based on magnetron sputtering and its application, so as to solve the following technical problems:
[0005] How to prevent catalyst CO poisoning and improve catalyst activity?
[0006] The purpose of the present invention can be achieved through the following technical solutions:
[0007] In a first aspect, the present invention discloses a method for preparing a WC / Pt / C catalyst based on a magnetron sputtering method, comprising the following steps:
[0008] S1: taking a carbon support, performing acid washing and heat treatment, and obtaining a C substrate;
[0009] S2: In a high vacuum sputtering chamber, a platinum target is used to sputter a C substrate to form a uniform platinum nanoparticle layer on the surface of the C substrate to obtain a Pt / C substrate;
[0010] S3: In a high vacuum sputtering chamber, sputtering the Pt / C substrate using a tungsten carbide target to form a uniform tungsten carbide particle layer on the platinum layer of the Pt / C substrate to obtain a WC / Pt / C substrate;
[0011] S4: heat-treating the WC / Pt / C substrate to obtain a WC / Pt / C catalyst.
[0012] In a further embodiment of the present invention, when the amount of carbon carrier in step S1 is 100 g, in step S2, the sputtering conditions are: sputtering power 100 W, sputtering gas pressure 50 Pa, distance between platinum target and C substrate 5 cm, sputtering time 30 min.
[0013] In a further embodiment of the present invention: when the amount of the carbon carrier in step S1 is 100 g, in step S3, the sputtering conditions are: sputtering power 130-180 W, sputtering gas pressure 40-60 Pa, distance between tungsten carbide target and Pt / C substrate 6 cm, sputtering time 30-45 min;
[0014] Preferably, the sputtering power is 150 W, the sputtering pressure is 50 Pa, the distance between the tungsten carbide target and the Pt / C substrate is 6 cm, and the sputtering time is 40 min;
[0015] In a further embodiment of the present invention: in step S3, the purity of the tungsten carbide target is ≥ 98%.
[0016] In a further embodiment of the present invention: in step S4, the specific steps of the heat treatment are: placing the WC / Pt / C substrate in an argon atmosphere and heating it at 500° C. for 2 hours.
[0017] In a second aspect, the present invention further discloses an application of the WC / Pt / C catalyst prepared by magnetron sputtering as described above, which is used for preparing a fuel cell.
[0018] Beneficial effects of the present invention:
[0019] (1) The WC / Pt / C catalyst of the present invention has a tungsten carbide particle layer disposed outside the platinum nanoparticle layer. Tungsten carbide has an electronic structure similar to that of platinum and exhibits activity similar to that of platinum in an electrocatalytic reaction. The surface of tungsten carbide has a lower CO adsorption energy, which makes the adsorption of CO molecules on the WC surface less than that on the surface of platinum particles, thereby playing a role in resisting CO poisoning and reducing the degree of CO gas poisoning of the catalyst;
[0020] (2) The WC / Pt / C catalyst of the present invention has a tungsten carbide particle layer outside the platinum nanoparticle layer, which can not only reduce the degree of CO gas poisoning of the catalyst, but also avoid direct contact between the sulfonic acid group and the platinum particles, thereby reducing the poisoning effect of the sulfonic acid group while maintaining the activity of the catalyst;
[0021] (3) During the preparation process of the WC / Pt / C catalyst of the present invention, platinum nanoparticles and tungsten carbide particles are sequentially sputtered on a carbon carrier by magnetron sputtering technology, which can improve the dispersibility and uniformity of the platinum nanoparticles and tungsten carbide particles, thereby improving the activity of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The present invention will be further described below in conjunction with the accompanying drawings.
[0023] Figure 1 It is a comparison diagram of polarization curves obtained by performing polarization performance tests on single cells corresponding to Examples 1-3 of the present invention and Comparative Examples 1-2. DETAILED DESCRIPTION
[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0025] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.
[0026] Example 1
[0027] 100 g of a carbon carrier with a high specific surface area is taken, and acid-washed and heat-treated to increase the surface activity to obtain a C substrate; a platinum target and a C substrate are set in a high vacuum sputtering chamber, and the sputtering power is controlled to be 100 W, the sputtering pressure is controlled to be 50 Pa, the distance between the target and the substrate is 5 cm, and the sputtering time is 30 minutes, so that a uniformly distributed platinum nanoparticle layer is formed on the surface of the C substrate to obtain a Pt / C substrate; a tungsten carbide target with a purity of 98% and a Pt / C substrate are set in a high vacuum sputtering chamber, and the sputtering power is controlled to be 130 W, the sputtering pressure is controlled to be 40 Pa, the distance between the target and the substrate is 6 cm, and the sputtering time is 30 minutes, so that a uniform tungsten carbide particle layer is formed on the platinum layer of the Pt / C substrate to obtain a WC / Pt / C substrate; the WC / Pt / C substrate is heat-treated in an argon atmosphere at a temperature of 500° C. for 2 hours to obtain a WC / Pt / C catalyst.
[0028] Example 2
[0029] Compared with Example 1, the only difference is that when sputtering the tungsten carbide target on the Pt / C substrate, the sputtering power is increased to 150 W, the sputtering gas pressure is increased to 50 Pa, the sputtering time is 40 min, and other conditions are exactly the same, and finally a WC / Pt / C catalyst is obtained.
[0030] Example 3
[0031] Compared with Example 1, the only difference is that when sputtering the tungsten carbide target on the Pt / C substrate, the sputtering power is increased to 180 W, the sputtering gas pressure is increased to 60 Pa, the sputtering time is 45 min, and other conditions are exactly the same, and finally a WC / Pt / C catalyst is obtained.
[0032] Comparative Example 1
[0033] The traditional Pt / C catalyst was used as a control.
[0034] Comparative Example 2
[0035] 100 g of a carbon carrier with a high specific surface area was taken, and acid-washed and heat-treated to increase the surface activity to obtain a C substrate; a platinum target and a C substrate were set in a high vacuum sputtering chamber, and the sputtering power was controlled to be 100 W, the sputtering pressure was 50 Pa, the distance between the target and the substrate was 5 cm, and the sputtering time was 30 minutes to form a uniformly distributed platinum nanoparticle layer on the surface of the C substrate to obtain a Pt / C substrate; the Pt / C substrate was heat-treated in an argon atmosphere at a temperature of 500°C for 2 hours to obtain a Pt / C catalyst.
[0036] The performance of the catalysts prepared in Examples 1-3 and Comparative Examples 1-2 was tested in accordance with the following steps.
[0037] The first step is to prepare 5 groups of catalyst slurries containing the catalysts prepared in Examples 1-3 and Comparative Examples 1-2, respectively, and mark them to distinguish them. The preparation method is: add 0.5 g of catalyst to 3.77 mL of perfluorosulfonic acid resin solution (Nafion content is 5%), and then add water and isopropanol in a volume ratio of 1:5 to form an ink-like slurry with a solid content of 2.7%. The slurry is dispersed at a high speed of 30 m / s for 30 min at a slurry temperature of 15°C to form a uniformly dispersed catalyst slurry.
[0038] In the second step, five single cells containing the five groups of catalyst slurries prepared in the first step were prepared. The preparation method was as follows: the catalyst slurry was evenly sprayed on a 12 μm thick proton exchange membrane to form a CCM. The spraying temperature was 90 ° C and the spraying area was 5 × 5 cm 2 , CCM loading is 0.5 mg / cm 2 The loading ratio of the anode surface to the cathode surface is 1:4. A 180um thick gas diffusion layer is placed on both sides of the above CCM, and a single cell is prepared using a graphite single serpentine plate.
[0039] In the third step, the five cells corresponding to Examples 1-3 and Comparative Examples 1-2 obtained in the second step are tested for electrical performance using a fuel cell test system. The system uses compressed air and high-purity hydrogen as reactants. The system is equipped with an external humidification system to obtain different gas humidification effects by controlling the temperature of the humidifier. The specific test method is as follows: before the test, the MEA (membrane electrode assembly) is activated first, the purpose of which is to make the proton exchange membrane and the Nafion resin contained in the catalyst layer contain sufficient water to ensure sufficient conductivity; after the working conditions are stable, the battery is controlled to have different discharge currents or voltages, and after the test is completed, the experimental data is derived. The single cell of the fuel cell is composed of a membrane electrode, a plate, a sealing gasket and an end plate, wherein the plate is an airtight hard graphite plate with a size of 50×50×3mm, and the inner side is designed as a parallel single serpentine; the sealing gasket is an ordinary plastic gasket; the end plate is a stainless steel plate; and the components are tightly assembled to reduce the internal resistance of the battery. The effective area of the membrane electrode in the homemade single cell is 25cm 2 , the effective area of the electrode is 25cm 2 After the membrane electrode is installed into the single experimental cell, the single cell performance test is carried out on the test bench. During the polarization test, the humidity of hydrogen and oxygen in the electrochemical performance test conditions of the membrane electrode is 50% RH, the hydrogen pressure and oxygen pressure are adjusted to 0.28MPa and 0.30MPa respectively, the single cell is connected to an external constant current and constant voltage power supply, the battery temperature is raised to 80℃, and the voltage-current curve of the battery is measured.
[0040] After the above tests, we get Figure 1 The polarization curve comparison diagram shown is Figure 1 By analyzing the results in , it can be learned that: the voltage value results in the polarization curves corresponding to Examples 1-3 are higher than the voltage value results in the polarization curves corresponding to Comparative Examples 1-2. This is because, in the low-current density region, the hydrogen oxidation reaction kinetics are slow, CO is easily adsorbed on the catalyst surface and accumulated, and the introduction of tungsten carbide prevents CO gas from being fully adsorbed on the platinum particles, reducing the effect of CO gas poisoning; at the same time, in the high-current density region, the cathode oxygen reduction reaction rate is accelerated, and the sulfonic acid group is easy to interact with the platinum catalyst, while the tungsten carbide particles effectively avoid direct contact between the platinum particles and the sulfonic acid group, reducing the poisoning effect of the sulfonic acid group, and enhancing the catalyst activity.
[0041] At the same time, in Examples 1-3, Example 2 has better polarization performance, which means that under the sputtering parameters of sputtering power of 150 W, sputtering gas pressure of 50 Pa, distance between tungsten carbide target and Pt / C substrate of 6 cm, and sputtering time of 40 min, the WC film has the best particle dispersion and film thickness, and achieves the best polarization performance; the polarization effect of Comparative Example 1 is worse than that of Comparative Example 2, which shows that loading a platinum nanoparticle layer on a carbon carrier by magnetron sputtering can improve the catalyst activity to a certain extent.
[0042] In summary, the WC / Pt / C catalyst of the present invention has stronger polarization performance and can be applied to fuel cells.
[0043] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction and a specific direction structure and operation, and therefore, cannot be understood as a limitation on the present invention. In addition, "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.
[0044] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0045] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.
Claims
1. A method for preparing a WC / Pt / C catalyst based on magnetron sputtering, characterized in that: The steps include: S1: taking a carbon support, performing acid washing and heat treatment, and obtaining a C substrate; S2: In a high vacuum sputtering chamber, a platinum target is used to sputter a C substrate to form a uniform platinum nanoparticle layer on the surface of the C substrate to obtain a Pt / C substrate; S3: In a high vacuum sputtering chamber, sputtering the Pt / C substrate using a tungsten carbide target to form a uniform tungsten carbide particle layer on the platinum layer of the Pt / C substrate to obtain a WC / Pt / C substrate; S4: heat-treating the WC / Pt / C substrate to obtain a WC / Pt / C catalyst.
2. The method for preparing a WC / Pt / C catalyst based on magnetron sputtering according to claim 1, characterized in that: When the amount of carbon carrier used in step S1 is 100 g, in step S2, the sputtering conditions are: sputtering power 100 W, sputtering gas pressure 50 Pa, distance between platinum target and C substrate 5 cm, sputtering time 30 min.
3. The method for preparing a WC / Pt / C catalyst based on magnetron sputtering according to claim 2, characterized in that: When the amount of carbon carrier used in step S1 is 100 g, in step S3, the sputtering conditions are: sputtering power 130-180 W, sputtering gas pressure 40-60 Pa, distance between tungsten carbide target and Pt / C substrate 6 cm, sputtering time 30-45 min.
4. The method for preparing a WC / Pt / C catalyst based on magnetron sputtering according to claim 1, characterized in that: In step S3, the purity of the tungsten carbide target is ≥ 98%.
5. The method for preparing a WC / Pt / C catalyst based on magnetron sputtering according to claim 1, characterized in that: In step S4, the specific steps of the heat treatment are: placing the WC / Pt / C substrate in an argon atmosphere and heating it at 500° C. for 2 hours.
6. An application of preparing WC / Pt / C catalyst based on magnetron sputtering method according to any one of claims 1 to 5, characterized in that: Used to prepare fuel cells.