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CN-121484105-B - Preparation method and application of ionic liquid vacuum impregnation Pt/C catalyst

CN121484105BCN 121484105 BCN121484105 BCN 121484105BCN-121484105-B

Abstract

The invention discloses a preparation method of an ionic liquid vacuum impregnation Pt/C catalyst and application thereof, wherein a carbon carrier is firstly mixed with water and alcohol for ball milling and is mixed with nitric acid to obtain an acid-treated carbon carrier; mixing metal platinum salt, an organic solvent, a surfactant and water to prepare a precursor solution, adding imidazole ionic liquid into the precursor solution for several times to obtain a precursor solution containing ionic liquid, mixing the solution with an acid-treated carbon carrier, carrying out vacuum ball milling and soaking to obtain mixed slurry, carrying out vacuum freeze drying to obtain freeze-dried powder, carrying out reduction treatment and heat treatment to obtain the ionic liquid doped Pt/C catalyst, and coating the slurry prepared by the catalyst on two sides of a proton exchange membrane to form a catalytic layer. By the mode, the method provided by the invention not only effectively inhibits agglomeration, migration and curing of platinum particles in the electrochemical process, thereby greatly improving the durability of the catalyst, but also enhancing the proton conductivity of the catalyst under the low humidity condition.

Inventors

  • WU CHENGXIANG
  • SHANG ZIQI
  • LIU JING
  • XU BIN
  • QIAN YU

Assignees

  • 江苏源氢新能源科技股份有限公司

Dates

Publication Date
20260505
Application Date
20260107

Claims (10)

  1. 1. The preparation method of the ionic liquid vacuum impregnation Pt/C catalyst is characterized by comprising the following steps of: (1) Mixing a carbon carrier, water and alcohol, performing ball milling, and then drying to obtain a pretreated carbon carrier; (2) Mixing the pretreated carbon carrier obtained in the step (1) with nitric acid, defoaming in vacuum, then performing heating treatment, washing and drying after the treatment to obtain an acid-treated carbon carrier; (3) Mixing metal platinum salt, an organic solvent, a surfactant and water to obtain a precursor solution; (4) After preparing the precursor solution in the step (3), adding imidazole ionic liquid for 2-3 times, adding for 6-8 hours each time, and uniformly stirring and mixing to obtain the precursor solution containing the ionic liquid; (5) Mixing the precursor solution containing the ionic liquid obtained in the step (4) with the acid-treated carbon carrier obtained in the step (2), and carrying out vacuum ball milling impregnation to obtain mixed slurry; (6) Performing pre-freezing treatment on the mixed slurry obtained in the step (5), and performing vacuum freeze drying to obtain freeze-dried powder; (7) And (3) carrying out reduction treatment on the freeze-dried powder obtained in the step (6) in a reducing gas atmosphere, and then carrying out heat treatment in an inert gas atmosphere to obtain the ionic liquid doped Pt/C catalyst.
  2. 2. The method for preparing an ionic liquid vacuum impregnation Pt/C catalyst according to claim 1, wherein in the step (1), the carbon carrier is one or more of carbon nanofibers, conductive carbon black, graphene or carbon nanotubes.
  3. 3. The method for preparing the ionic liquid vacuum impregnation Pt/C catalyst according to claim 1, wherein in the step (3), the metal platinum salt is chloroplatinic acid, the organic solvent is one or more of ethanol, isopropanol, n-butanol and n-propanol, and the surfactant is polyvinylpyrrolidone or cetyl trimethyl ammonium bromide.
  4. 4. The method for preparing the ionic liquid vacuum impregnation Pt/C catalyst according to claim 1, wherein in the step (4), the imidazole ionic liquid is one or more of 1-ethyl-3-methylimidazole diimine, 1-butyl-3-methylimidazole diimine or 1-butyl-2, 3-dimethylimidazole diimine.
  5. 5. The method for preparing the ionic liquid vacuum impregnation Pt/C catalyst according to claim 1, wherein in the step (5), the vacuum ball milling impregnation method comprises ball milling for 1-4 hours at a rotation speed of 250-800 rpm, then defoaming for 1-30 minutes at a vacuum degree of 10-50 kPa, and then ball milling for 1-4 hours again at a rotation speed of 250-800 rpm.
  6. 6. The method for preparing the ionic liquid vacuum impregnation Pt/C catalyst according to claim 1, wherein in the step (6), the pre-freezing treatment is freezing in liquid nitrogen or a low-temperature environment of-45 ℃, the temperature rising rate of vacuum freeze drying is 5 ℃ per minute, and the temperature range is-80 ℃ to-45 ℃.
  7. 7. The method for preparing the ionic liquid vacuum impregnation Pt/C catalyst according to claim 1, wherein in the step (7), the reducing gas is hydrogen or carbon monoxide, the inert gas is nitrogen or argon, the reducing temperature is 80-150 ℃, the heat treatment is sectional heat treatment, the heat treatment is used for carbonization heat treatment and hole adjustment, and the heat treatment temperature is 300-700 ℃.
  8. 8. A membrane electrode, characterized in that the catalytic layer comprises the ionic liquid vacuum impregnated Pt/C catalyst prepared by the preparation method of any one of claims 1 to 7, and the preparation method comprises mixing the ionic liquid vacuum impregnated Pt/C catalyst, deionized water, isopropanol and perfluorosulfonic acid resin solution to prepare catalyst slurry, and coating the slurry on two sides of a proton exchange membrane to form the catalytic layer.
  9. 9. The membrane electrode according to claim 8, wherein the perfluorinated sulfonic acid resin solution is one or more of Nafion 520 solution, nafion 1020 solution and Nafion 2020 solution, and the proton exchange membrane is a GORE membrane with a thickness of 8-15 μm.
  10. 10. The membrane electrode of claim 8 wherein the platinum loading is 0.3 mg/cm2 in the cathode catalytic layer on one side of the proton exchange membrane and 0.1 mg/cm2 in the anode catalytic layer on the other side.

Description

Preparation method and application of ionic liquid vacuum impregnation Pt/C catalyst Technical Field The invention relates to the field of catalysts for fuel cells, in particular to a preparation method of an ionic liquid vacuum impregnation high-performance high-durability platinum carbon (Pt/C) catalyst and a membrane electrode comprising the catalyst. Background Proton Exchange Membrane Fuel Cells (PEMFCs) are used as an efficient and clean energy conversion device, and have wide application prospects in the fields of traffic, stationary power generation and the like. However, large-scale commercialization still faces two major core challenges of cost and durability. On the one hand, cathodic oxygen reduction (ORR) kinetics are slow, and currently rely heavily on high-loading platinum (Pt) based catalysts to maintain adequate reaction rates, while the scarcity of platinum resources and Gao Angjia g directly drive up the cost of fuel cell systems. Therefore, the development of a high activity, low platinum loading catalyst is a necessary way to reduce costs. On the other hand, in the actual operation of the fuel cell, the catalyst is easy to decay particularly under severe working conditions such as vehicle start-stop, high potential and low humidity. The Pt nano particles of the Pt/C catalyst prepared by the traditional impregnation method are easy to gather and migrate on the surface of a carbon carrier, and grow up through the Oswald ripening process, so that the loss of electrochemical active area and the performance reduction are caused. In addition, the absence of proton conducting networks under low humidity conditions further exacerbates performance degradation. Then, the existing preparation method is difficult to combine high dispersion, high stability and low humidity adaptability. For example, conventional impregnation and drying processes are difficult to achieve efficient and uniform loading of Pt in the internal channels of the support, while most additives or coatings are susceptible to degradation or loss under high potential, high humidity conditions and are not capable of providing long-lasting protection under all operating conditions of the fuel cell. Therefore, an innovative catalyst preparation method is needed to be invented, and the structural stability and environmental tolerance of the catalyst under severe working conditions are remarkably improved while high-dispersion and high-activity platinum load is realized, so that the commercialization process of high-performance, long-service-life and low-cost PEMFC is promoted. Disclosure of Invention The invention mainly solves the technical problems of providing a preparation method and application of an ionic liquid vacuum impregnation Pt/C catalyst, which can solve the problems that the conventional method is difficult to realize uniform dispersion of nano particles under high platinum load and has insufficient stability under severe working conditions such as low humidity and the like, and realize high activity, long service life and excellent environmental adaptability of the catalyst. In order to solve the technical problems, the invention adopts a technical scheme that the preparation method of the ionic liquid vacuum impregnation Pt/C catalyst comprises the following steps: (1) Mixing a carbon carrier, water and alcohol according to the mass ratio of (10-13) to (6-7.5), performing ball milling, and drying to obtain a pretreated carbon carrier; (2) Mixing the pretreated carbon carrier obtained in the step (1) with nitric acid with the concentration of 3-5 mol/L, wherein the mass ratio is (6-10) 1, defoaming treatment under 10-50 kPa vacuum, then heating treatment for 1-10 hours at 60-150 ℃, washing and drying after treatment to obtain an acid-treated carbon carrier; (3) Mixing metal platinum salt, an organic solvent, a surfactant and water to prepare a precursor solution with the mass concentration of platinum metal of 5-8wt%, wherein the mass of the surfactant is 0.3-0.4 times of the mass of platinum metal; (4) After preparing the precursor solution in the step (3), adding imidazole ionic liquid for 2-3 times, wherein each time of adding is 6-8 hours apart, stirring for 20-36 hours, and uniformly mixing to obtain the precursor solution containing the ionic liquid, wherein the total adding mass of the imidazole ionic liquid is 1.5-2.5 times of the mass of platinum metal; (5) Mixing the precursor solution containing the ionic liquid obtained in the step (4) with the acid-treated carbon carrier obtained in the step (2), controlling the mass ratio of platinum metal in the precursor solution to the acid-treated carbon carrier to be (1.3-1.7): 1, and carrying out vacuum ball milling impregnation to obtain mixed slurry; (6) Performing pre-freezing treatment on the mixed slurry obtained in the step (5), and performing vacuum freeze drying to obtain freeze-dried powder; (7) And (3) carrying out reduction treatment on the freeze-dried