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CN-121974326-A - Sulfur-nitrogen co-doped mesoporous carbon material with adjustable aperture for fuel cell

CN121974326ACN 121974326 ACN121974326 ACN 121974326ACN-121974326-A

Abstract

The invention belongs to the technical field of fuel cells, and provides a sulfur-nitrogen co-doped mesoporous carbon material with adjustable aperture for fuel cells, and a preparation method and application thereof, wherein the preparation method comprises the steps of taking organic magnesium salt, polyhydroxy compound capable of melting and gelling at 200-300 ℃ and a sulfur-nitrogen element compound-urea compound as raw materials, dissolving and uniformly mixing, and then carrying out heating polymerization and microwave-assisted uniform dispersion; the mixed solution is gradually converted into a uniform gel precursor along with the volatilization of the solvent, ground into powder, subjected to three-stage gradient carbonization program heating carbonization treatment under the protection of inert atmosphere, and the template is removed through acid washing, so that the target product is obtained. The invention realizes the directional adjustment of the mesoporous size and the pore diameter distribution, and can effectively optimize the mass transfer path by virtue of the high specific surface area and the adjustable mesoporous structure, thereby remarkably improving the oxygen reduction reaction activity, the polarization performance and the long-term stability when being used as a fuel cell cathode catalyst carrier.

Inventors

  • ZHU FENGJUAN
  • WANG LINA
  • WU AIMING
  • WU RUOFEI

Assignees

  • 上海唐锋能源科技有限公司

Dates

Publication Date
20260505
Application Date
20260120

Claims (10)

  1. 1. The preparation method of the sulfur-nitrogen co-doped mesoporous carbon material with adjustable pore diameter for the fuel cell is characterized by comprising the following steps of: s1, dissolving an organic magnesium salt compound in water to form a dispersion system A; S2, dissolving a polyhydroxy compound which can be melted and gelled at 200-300 ℃ in water to form a dispersion system B; S3, uniformly mixing the dispersion system A and the dispersion system B, adding the organic sulfur nitrogen compound-urea compound, and stirring and dissolving to form a uniform blend C; s4, heating and polymerizing the blend C, and introducing microwave radiation to promote gelation to obtain uniformly dispersed gel; s5, carrying out temperature programming under the protection of inert atmosphere after grinding the gel, and carrying out three-stage gradient carbonization of 'generation of a pre-carbonization-template and stabilization of a mesoporous structure-carbon material'; s6, removing the magnesium oxide template from the collected pyrolysis product through acid washing, and washing and drying to obtain the sulfur-nitrogen co-doped mesoporous carbon material.
  2. 2. The process according to claim 1, wherein in step S1, the organomagnesium compound has the general formula Mg x (L) y ·nH 2 O, wherein L is C 4 -C 12 hydroxycarboxylic acid, x and y are positive integers satisfying charge balance and satisfy 2x=y·z, z is the number of charges of L, x, y and z are each selected from 1,2 or 3, n is 1 or more.
  3. 3. The preparation method according to claim 2, wherein the organic magnesium salt compound is selected from any one of magnesium gluconate, magnesium lactobionate, magnesium citrate, magnesium tartrate and magnesium malate.
  4. 4. The method according to claim 1, wherein in step S2, the polyol is a sugar alcohol polyol selected from any one of sorbitol, xylitol and maltitol; And/or the mass ratio of the organic magnesium salt compound in the step S1 to the polyhydroxy compound in the step S2 is 2-6:4-8.
  5. 5. The preparation method according to claim 1, wherein in the step S3, the organic sulfur nitrogen compound is selected from any one of thiourea, ammonium thiocyanate, thiosemicarbazide, L-cysteine, thioacetamide and ammonium thiosulfate, and the molar ratio of sulfur nitrogen elements in the organic sulfur nitrogen compound-urea compound is 1:1.5-1:10.
  6. 6. The method according to claim 1, wherein in step S4, the temperature of the heating polymerization is 150 to 300 ℃ and the power of the microwave radiation is 300 to 500W.
  7. 7. The preparation method according to claim 1, wherein in the step S5, the temperature of the first stage of pre-carbonization is 200-350 ℃ for 1-3 hours, the temperature of the second stage of template generation and the fixation of the mesoporous structure is 450-600 ℃ for 1-3 hours, the temperature of the third stage of carbon material stabilization is 750-900 ℃ for 1-3 hours, and the temperature-rising rate of the programmed temperature is 1-20 ℃ per minute.
  8. 8. The preparation method according to claim 1, wherein in the step S6, the acid used for pickling is an environment-friendly acid selected from at least one of acetic acid, citric acid, oxalic acid and dilute hydrochloric acid, the concentration is 0.1-2M, and the pickling time is 3-8h.
  9. 9. A sulfur-nitrogen co-doped mesoporous carbon material with adjustable pore diameter for a fuel cell, which is prepared by the preparation method according to any one of claims 1-8.
  10. 10. A fuel cell cathode catalyst comprising the sulfur nitrogen co-doped mesoporous carbon material according to claim 9 as a support, and platinum or platinum alloy nanoparticles supported on the support.

Description

Sulfur-nitrogen co-doped mesoporous carbon material with adjustable aperture for fuel cell Technical Field The invention relates to the technical field of new energy materials and electrochemistry, in particular to a modified carbon material for a cathode of a proton exchange membrane fuel cell, and particularly relates to a sulfur-nitrogen co-doped mesoporous carbon material with adjustable pore diameter for a fuel cell, a controllable preparation method and application thereof in an oxygen reduction reaction catalyst or a catalyst carrier. Background The development of fuel cells is limited by slow oxygen reduction reactions at the cathode side and particle shedding or ripening due to corrosion of the carbon support, and therefore "low activity" and "poor stability" become core problems for fuel cell efficiency. Currently commercialized conventional carbon blacks such as Vulcan-72 have dominant micropores, smaller pore sizes (typically less than 2 nm), and are prone to inhibit the diffusion process of reactants (e.g., oxygen, hydrogen) and products (e.g., water). During operation of the fuel cell, the transport path of the gas to the catalyst active site becomes tortuous due to the microporous structure, thereby resulting in a decrease in mass transfer efficiency. On the other hand, in the actual operating environment of the fuel cell (such as the acidic condition, high potential, frequent start-stop and dynamic load change conditions in the proton exchange membrane fuel cell), the microporous structure is prone to structural degradation. For example, micropores in a carbon support may gradually collapse due to electrochemical oxidation, thereby causing agglomeration of catalyst particles, resulting in a decrease in the number of active sites, a decrease in catalytic performance, and stability failing to meet commercial demands. Elemental doping is an effective strategy to enhance the interaction between metal particles and the support, and can significantly inhibit particle agglomeration, thereby improving the stability of the catalyst. The doping atoms can regulate and control the electronic structure of the carbon skeleton, improve the intrinsic catalytic activity of the material (even if the material is not loaded with platinum, the material can have direct electrocatalytic activity), and the introduced defect sites can also serve as strong anchoring sites to effectively fix the platinum nano particles, inhibit migration and agglomeration behaviors of the platinum nano particles in the operation process, and further remarkably enhance the durability of the catalyst. The patent application CN119833658A prepares the Pt/C catalyst with excellent durability by introducing urea as a nitrogen source, wherein the doping of nitrogen element effectively inhibits the aggregation of platinum particles, and the structural stability and the cycle performance of the catalyst are obviously improved. Mesoporous carbon material refers to a carbon material (generally 2-50 nm) with pore diameter distribution mainly in a mesoporous interval, and has the advantages of high specific surface area, abundant mesopores, adjustable pore diameter and the like. The method is mainly applied to the fields of supercapacitors, adsorbents, battery catalysts, printing ink and the like at present. However, the traditional hard template method has the problems of complex synthesis process using SiO 2 template and environmental and safety, the soft template method has the problems of high template agent cost and long process route, and the aperture of the directly pyrolyzed carbon material can not be accurately regulated. Therefore, a new functional carbon material which has simple synthetic process route, easy removal of template, adjustable pore diameter and can enhance the anchoring between particles and a carrier through heteroatom doping is needed to solve the problems of catalyst activity and stability at the same time. Disclosure of Invention In order to solve the technical problems, the invention aims to provide a sulfur-nitrogen co-doped mesoporous carbon material with adjustable pore diameter for a fuel cell, and a preparation method and application thereof. The preparation method comprises the steps of taking an organic magnesium salt, a polyhydroxy compound capable of being melted and gelled at 200-300 ℃ and a sulfur-nitrogen element compound-urea compound as raw materials, dissolving and uniformly mixing the raw materials, carrying out heating polymerization and microwave-assisted uniform dispersion, gradually converting a mixed solution into a uniform gel precursor along with solvent volatilization, grinding the obtained precursor into powder, carrying out programmed heating carbonization treatment under the protection of inert atmosphere, and then removing a template through acid washing to obtain a target product. The key point of the invention is that magnesium oxide generated in situ in the pyrolysis process of the organ