Electro-adsorption platinum ion electrode active material and application thereof

Abstract

The invention discloses an electrode active material for electro-adsorption of platinum ions, which is prepared by the following steps: soaking a certain amount of biomass raw material in an activator solution, freeze-drying the mixed solution, transferring the material obtained in the previous step into a porcelain boat, heating to 800 DEG C at the heating rate of 10 DEG C / min, calcining the material for 3 hours under the condition that nitrogen is introduced as a protective gas, cooling to the room temperature, and drying to obtain the electrode active material for electro-adsorption of platinum ions. And naturally cooling the material obtained in the previous step, soaking in an HNO3 solution, centrifuging the mixed solution, washing the solution with deionized water until the solution is neutral, and finally drying at 70 DEG C to obtain the product. The material can have a good electro-adsorption effect on platinum ions, the electro-adsorption performance on the platinum ions is improved when the material serves as an electrode active material in a capacitive deionization module, and the material can be applied to platinum recovery in a waste platinum catalyst and is environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of hydrogen fuel cell and component preparation technology, specifically to an electroadsorption platinum ion electrode active material and its application. Background Technology

[0002] A fuel cell is a power generation device that directly converts the chemical energy present in fuel and oxidant into electrical energy. Externally, it resembles a battery with positive and negative electrodes and an electrolyte, but in reality, it doesn't "store" electricity; it's a "power plant." However, it requires electrodes, an electrolyte, and a redox reaction to generate electricity. With the gradual maturation of fuel cell technology and the rapid increase in the number of hydrogen refueling stations, the solid waste generated by fuel cells globally and in my country will increase significantly, and the cumulative amount of waste will gradually rise. At that time, the treatment, disposal, and recycling of fuel cell batteries will become an important environmental issue.

[0003] The membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEMFC) typically consists of seven layers hot-pressed together: an anode diffusion layer, an anode porous carbon layer, an anode catalyst layer, an electrolyte membrane, a cathode catalyst layer, a cathode porous carbon layer, and a cathode diffusion layer. The catalyst layer is composed of a carbon-supported platinum or platinum-ruthenium catalyst and a solid polymer electrolyte. The catalyst layer can be attached to either the porous carbon layer or the electrolyte membrane. After the MEA has been operating within the fuel cell for a certain period, the fuel cell becomes unusable due to external contamination, catalyst aggregation, membrane degradation, and rupture. However, the physicochemical properties of precious metals such as platinum and ruthenium in the catalyst layer of spent fuel cells remain unchanged; only their catalytic activity decreases. Recycling these precious metals is not only an effective way to conserve limited precious metal resources but also yields significant economic benefits. Currently, traditional methods for recycling precious metals from fuel cell MEAs include incineration and aqua regia impregnation. The incineration method involves scraping off the catalyst and solid polymer electrolyte from the catalyst layer, and even the carbon and PTFE from the porous carbon layer, and then incinerating them at high temperatures to convert the carbon, solid polymer electrolyte, and PTFE into carbon dioxide, water, and other gaseous fluorides. Its disadvantage is that the fluorides are highly toxic, severely polluting the workplace and the atmosphere. The aqua regia impregnation method, on the other hand, suffers from low catalyst recovery rates (approximately 60-70%) because much of the catalyst is encapsulated by the solid polymer electrolyte. Summary of the Invention

[0004] The main objective of this invention is to provide an electroadsorption platinum ion electrode active material and its application, which can effectively solve the problems in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing an electrode active material for adsorbing platinum ions, the method comprising the following steps:

[0007] S1: Take a certain amount of biomass raw materials and soak them in an activator solution, then freeze-dry the mixed solution;

[0008] S2: Transfer the material obtained in S1 to a ceramic boat and heat it to 800℃ at a heating rate of 10℃ / min. Calcinate the material for 3 hours under the condition of introducing nitrogen as a protective gas.

[0009] S3: After the material obtained in S2 is naturally cooled, it is soaked in HNO3 solution, then the mixed solution is centrifuged and washed with deionized water until neutral. Finally, it is dried at 70°C to obtain the electroadsorption platinum ion electrode active material.

[0010] The biomass raw material in step S1 is one or more of the following: orange peel, watermelon peel, winter melon peel, banana peel, and grapefruit peel.

[0011] The activator in step S1 is one of KOH, KHCO3, ZnCl2, and H3PO4.

[0012] A method for preparing an electrode sheet includes the following steps:

[0013] Step (1): Take a certain amount of an electrode active material for adsorbing platinum ions according to any one of claims 1-4, a conductive agent and a binder, add them to the conductive agent and mix them. Stir the mixture to disperse it evenly to obtain an electrode slurry.

[0014] Step (2) involves uniformly coating the electrode slurry obtained in step (1) onto the current collector, and finally drying the coated current collector at 60°C to obtain the electrode sheet.

[0015] The mass ratio of the electrode active material, conductive agent, and binder for adsorbing platinum ions is 70-95:10:10.

[0016] The effective area of ​​the current collector surface is 4×4CM. 2 .

[0017] An electrode sheet prepared by a certain method is used in a capacitor deionization module.

[0018] The beneficial effects of this invention are:

[0019] This invention uses nitrogen-doped porous biomass carbon as the electrode active material. The resulting electrode sheet is used in a capacitor deionization module. It can efficiently electro-adsorb platinum ions in the solution at a low voltage of 1V, and still has excellent adsorption capacity after multiple cycles. This has good application prospects in practice. Attached Figure Description

[0020] Figure 1The biomass carbon materials prepared in Example 1 are shown in the following images: (a) thermogravimetric analysis of orange peel material after KHCO3 activation; (b) SEM image of NC-800 material; (c) SEM image and (d) TEM image of NPC-800 material.

[0021] Figure 2 (a) Raman and (b) Fourier transform infrared spectra of the biomass carbon materials NPC-X and NC-800 prepared in Example 1.

[0022] Figure 3 The adsorption-desorption curves show the removal of platinum ions from a solution with a platinum ion concentration of 50 ppm and a pH of 4 by the NPC-800 material prepared in Example 1 under different voltages.

[0023] Figure 4 The adsorption-desorption curves show the removal of platinum ions from solutions with different platinum ion concentrations by the NPC-800 material prepared in Example 1 at a voltage of 1V.

[0024] Figure 5 The adsorption-desorption curves show the removal of platinum ions from platinum ion solutions at different pH values ​​by the NPC-800 material prepared in Example 1 at a voltage of 1V and a platinum ion concentration of 50ppm.

[0025] Figure 6 The retention rate of adsorption capacity of the NPC-800 material prepared in Example 1 after 20 cycles in a solution with a voltage of 1V, a platinum ion solution of 10ppm, and a pH of 4. Detailed Implementation

[0026] The technical solution of the present invention will now be described in detail through specific embodiments.

[0027] Example 1

[0028] The specific preparation method of nitrogen-doped porous biomass carbon materials includes the following steps:

[0029] Orange peel was chopped and placed in a KHCO3 solution, stirred evenly for 30 minutes, then removed and freeze-dried for 48 hours. The freeze-dried orange peel was then heated to 800℃ at a rate of 10℃ / min and calcined for 3 hours. For comparison, calcination temperatures of 600℃, 700℃, 900℃, and direct calcination at 800℃ without KHCO3 activation were also used. After natural cooling, the calcined material was immersed in 60 mL of diluted HNO3 solution (50% by volume). Finally, the sample was centrifuged, washed several times with deionized water, and dried at 65℃ to obtain black NPC powder.

[0030] The thermogravimetric analysis of the orange peel material after KHCO3 activation obtained in Example 1 is as follows: Figure 1As shown in Figure a, it can be seen that the mass loss below 200℃ is attributed to water desorption; between 200℃ and 400℃, it is attributed to the carbonization of orange peel and the decomposition of KHCO3; and after 400℃, it is attributed to a series of reactions between the intermediates of KHCO3 decomposition and the graphitized orange peel. SEM images of the NC-800 material are shown below. Figure 1 As shown in b; SEM and TEM images of NPC-800 materials are shown in Figure 1. Figure 1 As shown in c and 1d.

[0031] from Figure 1 Figures a, b, and c show that orange peel activated with KHCO3 produces a large number of pores after calcination.

[0032] The Raman spectrum of the material obtained in Example 1 is as follows: Figure 2 As shown in a, the infrared spectrum is as follows: Figure 2 As shown in b. Figure 2 As can be seen from this, NPC-800 has the largest ID / IG value, indicating that NPC-800 has a large number of defects, which facilitates ion adsorption; from Figure 2 b shows that the carbon material derived from orange peel is rich in oxygen functional groups on its surface.

[0033] Example 2

[0034] Similar to Example 1, except that the orange peel is replaced with winter melon peel.

[0035] Example 3

[0036] Similar to Example 1, except that the orange peel is replaced with watermelon peel.

[0037] Example 4

[0038] Similar to Example 1, except that the orange peel is replaced with grapefruit peel.

[0039] Example 5

[0040] Same as Example 1, except that KHCO3 is replaced with KOH.

[0041] Example 6

[0042] Same as Example 1, except that KHCO3 is replaced with ZnCl2.

[0043] Example 7

[0044] Same as Example 1, except that KHCO3 is replaced with H3PO4.

[0045] Example 8

[0046] An electrode sheet is prepared by the following steps:

[0047] The nitrogen-doped porous carbon material, polyvinylidene fluoride, and Ketjen black prepared in Example 1 were added to a dimethylformamide solution at a mass ratio of 8:1:1 and mixed. The mixture was stirred to obtain an electrode slurry. The electrode slurry was then uniformly coated onto a titanium electrode sheet with an effective area of ​​4×4 cm2. Finally, the electrode sheet was dried overnight in a 65°C oven to obtain the desired electrode sheet.

[0048] Example 9

[0049] Same as Example 8, except that polyvinylidene fluoride is replaced with polytetrafluoroethylene.

[0050] Example 10

[0051] Same as Example 8, except that polyvinylidene fluoride is replaced with naphthalene.

[0052] To verify the electroadsorption performance of the NPC-800 material prepared in this invention for platinum ions, the removal effect of the NPC-800 material obtained in Example 1 on copper ions in a solution with a platinum ion concentration of 50 ppm was tested under different voltage conditions, and the removal effect of the NPC-800 material on platinum ions in solutions with different concentrations of platinum ions was also tested at 1 V. The test results are as follows: Figure 3 and 4 As shown. From Figure 3 It can be seen that the amount of platinum ions removed increases with increasing voltage; from Figure 4 It can be seen that the adsorption capacity is already saturated when the platinum ion concentration reaches 50 ppm.

[0053] To test the electroadsorption performance of the NPC-800 material prepared in this invention for platinum ions under different acidic pH conditions, the removal effect of the NPC-800 material obtained in Example 1 on platinum ions was measured at pH values ​​between 2 and 4. The results are as follows: Figure 5 As shown. From Figure 5 As can be seen, the removal effect of platinum ions is better as the pH value increases.

[0054] Finally, to test the cyclic stability of platinum ion electroadsorption on the NPC-800 material, the NPC-800 prepared in Example 1 was subjected to cyclic adsorption of platinum ions, as follows: Figure 6 As shown in the figure, the electrode material still exhibits excellent adsorption performance for platinum ions after multiple cycles.

[0055] The structures, proportions, and sizes depicted in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, terms such as "upper," "lower," "front," "rear," and "middle" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

Claims

1. A method for preparing an electrode active material for adsorbing platinum ions, characterized in that, The preparation method includes the following steps: S1: Take a certain amount of biomass raw materials and soak them in an activator solution, then freeze-dry the mixed solution; S2: Transfer the material obtained in S1 to a ceramic boat and heat it to 800℃ at a heating rate of 10℃ / min. Calcinate the material for 3 hours under the condition of introducing nitrogen as a protective gas. S3: After the material obtained in S2 is naturally cooled, it is soaked in HNO3 solution, then the mixed solution is centrifuged and washed with deionized water until neutral. Finally, it is dried at 70°C to obtain the electroadsorption platinum ion electrode active material.

2. The method for preparing an electrode active material for adsorbing platinum ions according to claim 1, characterized in that: The biomass raw material in step S1 is one or more of the following: orange peel, watermelon peel, winter melon peel, banana peel, and grapefruit peel.

3. The method for preparing an electrode active material for adsorbing platinum ions according to claim 1, characterized in that: The activator in step S1 is one of KOH, KHCO3, ZnCl2, and H3PO4.

4. A method for preparing an electrode sheet, characterized in that, Includes the following steps: Step (1): Take a certain amount of an electrode active material for adsorbing platinum ions according to any one of claims 1-4, a conductive agent and a binder, add them to the conductive agent and mix them. Stir the mixture to disperse it evenly to obtain an electrode slurry. Step (2) involves uniformly coating the electrode slurry obtained in step (1) onto the current collector, and finally drying the coated current collector at 60°C to obtain the electrode sheet.

5. The method for preparing an electrode sheet according to claim 4, characterized in that: The mass ratio of the electrode active material, conductive agent, and binder for adsorbing platinum ions is 70-95:10:

10.

6. The method for preparing an electrode sheet according to claim 1, characterized in that: The effective area of ​​the current collector surface is 4×4CM. 2 .

7. The application of an electrode sheet prepared by any of the electrode sheet preparation methods described in claims 4-6 in a capacitor deionization module.

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