Microporous catalytic layer of fuel cell for space power supply and preparation method therefor

Abstract

A microporous catalytic layer of a fuel cell for a space power supply and a preparation method therefor. A cathode catalyst slurry comprises a Pt / metal oxide catalyst, a perfluorosulfonic acid ionomer, ultrapure water, and isopropyl alcohol; and an anode catalyst slurry comprises an IrO2-Pt / metal oxide catalyst, a perfluorosulfonic acid ionomer, ultrapure water, and isopropyl alcohol. The particle sizes of the Pt / metal oxide catalyst and the IrO2-Pt / metal oxide catalyst in the catalytic layer are in a gradient distribution; and the mass ratio of the perfluorosulfonic acid ionomer to a metal oxide carrier in both the anode catalyst slurry and the cathode catalyst slurry in the catalytic layer is in a gradient distribution, wherein the mass ratio of the perfluorosulfonic acid ionomer to ultrapure water and isopropyl alcohol is unchanged. The microporous catalytic layer of a fuel cell for a space power supply has high catalytic activity and strong durability, and can allow water generated in the catalytic layer to be directionally discharged, thereby enhancing the water management capability of a membrane electrode assembly under a space microgravity condition.

Description

A fuel cell microporous catalytic layer for space power supply and a preparation method thereof TECHNICAL FIELD

[0001] The present application relates to the field of fuel cells, in particular to a fuel cell microporous catalytic layer for space power supply and a preparation method thereof. BACKGROUND

[0002] Proton exchange membrane fuel cell (PEMFC) is a kind of high-efficiency and environmentally friendly energy conversion equipment that directly converts the chemical energy of hydrogen and oxygen into electrical energy, and its energy conversion efficiency is as high as 50-60%, and it is small in size and light in weight, and the byproduct water can be used for astronauts to drink. In addition, the waste heat discharged from the fuel cell system is about 50-70 DEG C, which can be used for the thermal management of spacecraft, so the fuel cell power supply has great application prospects in space stations, manned spacecraft and lunar bases.

[0003] Membrane electrode (MEA) is the most core component of PEMFC, and is the multi-phase mass transfer and electrochemical reaction place of energy conversion, involves three-phase interface reaction and complex mass and heat transfer process, and directly determines the performance, service life and cost of PEMFC. The catalytic layer plays a crucial role in the proton exchange membrane fuel cell, which is usually composed of catalyst, carbon carrier, ionomer and pore. These components together form a porous structure to promote the electrochemical reaction of hydrogen and oxygen at the anode and cathode. However, the existing space hydrogen-oxygen fuel cell uses pure oxygen as the reactant, and the flow is small, and the product water cannot be discharged from the reaction zone in time, which easily causes waterlogging and affects the mass transfer of the catalytic layer, thereby causing the failure of the cell. Therefore, there is an urgent need for a catalytic layer structure with strong water management ability to improve the water transport problem of the membrane electrode. SUMMARY

[0004] In order to solve the problems in the above background art, the purpose of the present application is to provide a fuel cell microporous catalytic layer for space power supply, which has high catalytic activity and strong durability, and the generated water in the catalytic layer can be discharged directionally, and the water management ability of the membrane electrode under the condition of space microgravity can be enhanced.

[0005] The technical problem solved by the present application is solved by the following scheme: a fuel cell microporous catalytic layer for space power supply, comprising an anode catalyst slurry and a cathode catalyst slurry, the cathode catalyst slurry comprising Pt / metal oxide catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol.

[0006] The anode catalyst slurry comprises IrO2-Pt / metal oxide catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol; the IrO2-Pt / metal oxide catalyst comprises a metal oxide carrier and IrO2, and the surface of the metal oxide carrier carries Pt nanoparticles;

[0007] The particle sizes of the Pt / metal oxide catalyst and the IrO2-Pt / metal oxide catalyst are gradiently distributed in the catalytic layer; the mass ratio of the perfluorosulfonic acid ionomer to the metal oxide carrier in the catalytic layer is gradiently distributed, and the mass ratio of the perfluorosulfonic acid ionomer to the ultrapure water and the isopropyl alcohol is constant.

[0008] Preferably, the particle size of the IrO2-Pt / metal oxide catalyst is 10-200 nm.

[0009] Preferably, the I / C ratio is 0.6-1.5.

[0010] The second object of the present application is to provide a preparation method of a fuel cell microporous catalytic layer for a space power supply, comprising the following steps:

[0011] Step one: preparing a metal oxide carrier

[0012] S1. Dissolving a metal oxide precursor in an acid solution to form a metal ion solution, and then adding ionized water to the metal ion solution until the concentration of metal ions in the metal ion solution is 0.1-1 mol / L;

[0013] S2. Adding an alkali solution as a precipitant dropwise to the metal ion solution until the metal ions in the solution are completely precipitated, and then filtering, washing and collecting the obtained precipitate, and then heat-decomposing the collected precipitate to obtain a metal oxide carrier;

[0014] Step two: preparing a Pt / metal oxide catalyst and an IrO2-Pt / metal oxide catalyst

[0015] S1. Separately weighing a metal oxide carrier, a platinum precursor, a reducing agent and a solvent, mixing the platinum precursor, the reducing agent and the solvent uniformly to obtain a mixed solution, adding the metal oxide carrier into the mixed solution, then stirring for 30 min, and then ultrasonicating for 30 min to obtain a reaction solution, and then adding an alkali solution to the reaction solution until the pH of the reaction solution is 9;

[0016] S2. The pH-adjusted reaction solution is placed in a sealed high-pressure reaction kettle and reacted at 120°C for 6h to obtain a yellow transparent solution, which is then subjected to standing cooling treatment, and 5% HNO3 aqueous solution is added dropwise until the pH of the yellow transparent solution is less than 5, followed by ultrasonic treatment for 15 min, filtration, and collection of the obtained powder, which is dried in a vacuum oven for 12h to obtain a Pt / metal oxide catalyst;

[0017] S3. The Pt / metal oxide catalyst and IrO2 are placed in a ball mill and mixed uniformly to obtain an IrO2-Pt / metal oxide catalyst, the particle size of the Pt / metal oxide catalyst being 10nm-1μm;

[0018] Step three: preparation of a catalyst slurry

[0019] S1. The IrO2-Pt / metal oxide catalyst, perfluorosulfonic acid ionomer, ultrapure water, and isopropyl alcohol are weighed and mixed uniformly to form an anode catalyst slurry;

[0020] S2. The Pt / metal oxide catalyst, perfluorosulfonic acid ionomer, ultrapure water, and isopropyl alcohol are weighed and mixed uniformly to form a cathode catalyst slurry;

[0021] Step four: preparation of a gradient catalyst layer

[0022] The anode catalyst slurry is sprayed onto the surface of a proton exchange membrane, wherein the proportions of the IrO2-Pt / metal oxide catalyst, ultrapure water, and isopropyl alcohol remain unchanged, and the particle size of the IrO2-Pt / metal oxide catalyst increases and the mass ratio of the perfluorosulfonic acid ionomer to the metal oxide carrier decreases along the direction away from the proton exchange membrane;

[0023] The cathode catalyst slurry is sprayed onto the other side of the surface of the proton exchange membrane, wherein the proportions of the Pt / metal oxide catalyst, ultrapure water, and isopropyl alcohol remain unchanged, and the particle size of the IrO2-Pt / metal oxide catalyst increases and the mass ratio of the perfluorosulfonic acid ionomer to the metal oxide carrier decreases along the direction away from the proton exchange membrane.

[0024] Preferably, the metal oxide precursor in step one is one or more of cerium salt solution, titanium salt solution, and zirconium salt solution.

[0025] Preferably, the platinum precursor in step two is one or more of chloroplatinic acid, tetraammine platinum nitrate, and phthalocyanine platinum.

[0026] The catalyst layer prepared by the above preparation method has excellent performance and stable structure.

[0027] The fourth object of the present application is to provide a fuel cell for space power supply. 2 .

[0028] The catalytic layer of the present application is solidified on the surface of the proton exchange membrane by spraying, and the gas diffusion layer is fixed on the surface of the cathode layer and the anode layer of the catalytic layer by hot pressing.

[0029] The fourth object of the present application is to provide a fuel cell for space power supply.

[0030] In the present application, the stability and electrocatalytic activity of the battery are further improved by combining the Pt / metal oxide catalyst with IrO2, and the influence of the space microgravity environment on the gas-liquid distribution and flow in the battery is reduced by combining the anti-reverse effect of IrO2, thereby improving the stability and life of the battery.

[0031] Secondly, by gradient distribution of the particle size of the Pt / metal oxide catalyst and the IrO2-Pt / metal oxide catalyst in the catalytic layer, and by gradient distribution of the mass ratio of the perfluorosulfonic acid ionomer to the metal oxide carrier in the catalytic layer, directional flow of water under capillary pressure is realized, and the specific demand of water management of the battery under space microgravity conditions is met.

[0032] In summary, the beneficial effects of the present application are:

[0033] The catalytic layer of the present application can improve the drainage capacity of the membrane electrode, and based on the principle of micropore fluid dynamics, combined with the improvement of the surface properties of the catalyst, directional flow of water under capillary pressure is realized, and the specific demand of water management of the battery under space microgravity conditions is met.

[0034] By increasing the thickness and structure arrangement of the catalytic layer without affecting the performance of the battery, the active site density in the catalytic layer is effectively increased, the drainage capacity of the catalytic layer is improved, the concentration polarization is reduced, and the power density of the battery is improved.

[0035] By strengthening the water vapor transmission path design in the catalytic layer structure, the slurry solidification molding process and the regulation of the three-phase reaction interface of the catalytic layer are studied, and an electrode structure with high transmission flux and high catalyst utilization rate is constructed.

[0036] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, the content of the specification can be implemented, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following preferred embodiments are described in detail, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a polarization performance comparison chart, Voltage (V) vs. Current Density (A / cm 2 ).

[0038] Figure 2 is a polarization performance comparison chart after accelerated durability test, Voltage (V) vs. Current Density (A / cm 2 ). DETAILED DESCRIPTION

[0039] In order to make the content of the present application more easily and clearly understood, the present application is further described below according to specific embodiments and in conjunction with the accompanying drawings.

[0040] A fuel cell microporous catalytic layer for space power supply, the cathode catalyst slurry comprises Pt / metal oxide catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol;

[0041] The anode catalyst slurry comprises IrO2-Pt / metal oxide catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol; the IrO2-Pt / metal oxide catalyst comprises a metal oxide carrier and IrO2, and the surface of the metal oxide carrier carries Pt nanoparticles;

[0042] The particle sizes of the Pt / metal oxide catalyst and the IrO2-Pt / metal oxide catalyst are gradiently distributed in the catalytic layer; the mass ratio of the perfluorosulfonic acid ionomer to the metal oxide carrier in the anode catalyst slurry and the cathode catalyst slurry is gradiently distributed in the catalytic layer, and the mass ratio of the perfluorosulfonic acid ionomer to the ultrapure water and the isopropyl alcohol is constant.

[0043] Preferably, the particle size of the Pt / metal oxide catalyst is 10-200 nm.

[0044] Preferably, the I / C ratio is 0.6-1.5.

[0045] A preparation method of a fuel cell microporous catalytic layer for space power supply, comprising the following steps:

[0046] Step one: preparing a metal oxide carrier

[0047] S1. Dissolving a metal oxide precursor in an acid solution to form a metal ion solution, and then adding ionized water to the metal ion solution until the concentration of metal ions in the metal ion solution is 0.1-1 mol / L;

[0048] S2. The alkaline solution is added dropwise into the metal ion solution until the metal ions in the solution are completely precipitated, followed by filtration, washing and collection of the obtained precipitate, and then the collected precipitate is subjected to thermal decomposition to obtain the metal oxide carrier.

[0049] The acid solution used in the above step is not particularly limited, and can be one or a mixture of several of sulfuric acid, hydrochloric acid, nitric acid and the like.

[0050] The alkaline solution used in the above step is not particularly limited, and can be one or a mixture of two of sodium hydroxide, ammonia, ammonium carbonate, potassium hydroxide and the like.

[0051] Step two: preparation of Pt / metal oxide catalyst and IrO2-Pt / metal oxide catalyst

[0052] S1. The metal oxide carrier, platinum precursor, reducing agent and solvent are weighed respectively, the platinum precursor, reducing agent and solvent are mixed uniformly to obtain a mixed solution, the metal oxide carrier is then added into the mixed solution, followed by stirring for 30 min and ultrasonic treatment for 30 min to obtain a reaction solution, and then an alkaline solution is added into the reaction solution until the pH of the reaction solution is 9;

[0053] S2. The reaction solution with adjusted pH is placed in a sealed high-pressure reaction kettle and reacted at 120°C for 6 h to obtain a yellow transparent solution, which is then subjected to standing cooling treatment, and then 5% HNO3 aqueous solution is added dropwise into the yellow transparent solution until the pH of the yellow transparent solution is less than 5, followed by ultrasonic treatment for 15 min, filtration and collection of the obtained powder, and then the obtained powder is dried in a vacuum oven for 12 h to obtain the Pt / metal oxide catalyst;

[0054] S3. The Pt / metal oxide catalyst and IrO2 are mixed uniformly in a ball mill to obtain the IrO2-Pt / metal oxide catalyst, and the particle size of the Pt / metal oxide catalyst is 10 nm to 1 μm.

[0055] Step three: preparation of catalyst slurry

[0056] S1. The IrO2-Pt / metal oxide catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol are weighed and mixed uniformly to form an anode catalyst slurry;

[0057] S2. The Pt / metal oxide catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol are weighed and mixed uniformly to form a cathode catalyst slurry;

[0058] Step four: preparation of gradient catalytic layer

[0059] Spraying the anode catalyst slurry to the surface of the proton exchange membrane, wherein the ratio of IrO2-Pt / metal oxide catalyst, ultrapure water and isopropanol is constant, the particle size of the IrO2-Pt / metal oxide catalyst increases in the direction away from the side of the proton exchange membrane, and the mass ratio of perfluorosulfonic acid ionomer to metal oxide carrier decreases.

[0060] Spraying the cathode catalyst slurry to the other side of the surface of the proton exchange membrane, wherein the ratio of Pt / metal oxide catalyst, ultrapure water and isopropanol is constant, the particle size of the IrO2-Pt / metal oxide catalyst increases in the direction away from the side of the proton exchange membrane, and the mass ratio of perfluorosulfonic acid ionomer to metal oxide carrier decreases.

[0061] The metal oxide precursor in step one is preferably but not limited to one or more of cerium salt solution, titanium salt solution, zirconium salt solution.

[0062] The platinum precursor in step two is preferably but not limited to one or more of chloroplatinic acid, tetraammine platinum nitrate, phthalocyanine platinum.

[0063] A membrane electrode of a fuel cell for space power supply, comprising a proton exchange membrane, a gas diffusion layer and a catalyst layer, the catalyst layer being any one of the microporous catalyst layers for fuel cells for space power supply according to claims 1-3, the thickness of the catalyst layer being 500 nm-20 μm, and the catalyst loading in the catalyst layer being 0.05-0.5 mg / cm 2 .

[0064] The perfluorosulfonic acid ionomer used in the following examples and comparative examples is specifically D520 ionomer.

[0065] Example One

[0066] Step one: preparation of TiO2 carrier

[0067] S1. Dissolve titanium tetrachloride in a PH<1 acid solution, then add deionized water to obtain a metal ion solution;

[0068] The concentration of titanium metal ions in the metal ion solution prepared by the above method is 0.1 mol / L, 0.3 mol / L, 0.5 mol / L and 0.7 mol / L, respectively;

[0069] S2. Use ammonia as a precipitant and add it dropwise to the metal ion solution until the pH of the solution is adjusted to 9, then stir uniformly, then centrifuge the metal ion solution at a centrifugal speed of 4000 r / min for 10 min to collect the precipitate, then wash the obtained precipitate with ethanol and deionized water, and then place the washed precipitate in a tube furnace for calcination, the calcination temperature is 350℃, and the calcination time is 30 min, to obtain a TiO2 carrier.

[0070] The TiO2 carriers numbered T-A, T-B, T-C and T-D were prepared by using the metal ion solutions with the titanium metal ion concentrations of 0.1 mol / L, 0.3 mol / L, 0.5 mol / L and 0.7 mol / L respectively. The TiO2 carriers with different numbers have different particle sizes.

[0071] Step two: preparation of IrO2-Pt / TiO2 catalyst and Pt / TiO2 catalyst

[0072] S1. Pour sodium citrate solid into a 50ml beaker, then add 10ml of ethylene glycol to completely dissolve the sodium citrate solid, and then dissolve 1g of H2PtCl6.6H2O in 50ml of ethylene glycol, wherein the molar ratio of sodium citrate to Pt is 2.5:1. Add 400mg of CeO2 carrier to the above ethylene glycol solution containing H2PtCl6, ultrasonic for 0.5h, then stir for 0.5h to obtain a reaction solution, and then adjust the pH value of the reaction solution to 9 with a 5wt% KOH / EG solution;

[0073] S2. Put the pH-adjusted reaction solution into a sealed high-pressure reaction kettle and react at 120℃ for 6h to obtain a yellow transparent solution, then perform standing cooling treatment on the yellow transparent solution, and then drop 5% HNO3 aqueous solution into it until the pH of the yellow transparent solution is less than 5, then perform ultrasonic treatment for 15min, then perform filtration and collect the obtained powder, and then put the obtained powder into a vacuum oven for drying for 12h to obtain a Pt / TiO2 catalyst;

[0074] In the S1 process of step two, by adding the TiO2 carriers numbered T-A, T-B, T-C and T-D, the Pt / TiO2 catalysts numbered PT-A, PT-B, PT-C and PT-D can be obtained respectively;

[0075] S3. Put the Pt / TiO2 catalyst obtained in the above step and 1wt% IrO2 into a ball mill for mixing and dispersing for 3h to obtain an IrO2-Pt / TiO2 catalyst.

[0076] In the S3 process of step two, by adding the Pt / TiO2 catalysts numbered PT-A, PT-B, PT-C and PT-D, the IrO2-Pt / TiO2 catalysts numbered PTI-A, PTI-B, PTI-C and PTI-D can be obtained respectively.

[0077] Step three: preparation of catalyst slurry

[0078] S1. Take PTI-A catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol by mass ratio 1:40:30:90, mix together, disperse by ball milling for 3h and mix uniformly, then disperse by high-speed shearing machine for 30min, form catalyst slurry numbered An.A;

[0079] Take PTI-B catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol by mass ratio 1:35:30:90, mix together, disperse by ball milling for 3h and mix uniformly, then disperse by high-speed shearing machine for 30min, form catalyst slurry numbered An.B;

[0080] Take PTI-C catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol by mass ratio 1:30:30:90, mix together, disperse by ball milling for 3h and mix uniformly, then disperse by high-speed shearing machine for 30min, form catalyst slurry numbered An.C;

[0081] Take PTI-D catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol by mass ratio 1:25:30:90, mix together, disperse by ball milling for 3h and mix uniformly, then disperse by high-speed shearing machine for 30min, form catalyst slurry numbered An.D.

[0082] An.A, An.B, An.C and An.D catalyst slurry are anode catalyst slurry.

[0083] S1. Take PT-A catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol by mass ratio 1:40:30:90, mix together, disperse by ball milling for 3h and mix uniformly, then disperse by high-speed shearing machine for 30min, form catalyst slurry numbered Ca.A;

[0084] Take PT-B catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol by mass ratio 1:35:30:90, mix together, disperse by ball milling for 3h and mix uniformly, then disperse by high-speed shearing machine for 30min, form catalyst slurry numbered Ca.B;

[0085] Take PT-C catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol by mass ratio 1:30:30:90, mix together, disperse by ball milling for 3h and mix uniformly, then disperse by high-speed shearing machine for 30min, form catalyst slurry numbered Ca.C;

[0086] PT-D catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed according to the mass ratio of 1:25:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered as Ca.D.

[0087] The Ca.A, Ca.B, Ca.C and Ca.D catalyst slurries are cathode catalyst slurries.

[0088] Step four: preparation of a gradient catalyst layer

[0089] The Ca.A, Ca.B, Ca.C and Ca.D are sprayed onto the surface of the proton exchange membrane in turn by the spraying method until the Pt loading of the catalyst layer reaches 0.4mg / cm 2 After drying, the An.A, An.B, An.C and An.D slurries are sprayed onto the other surface of the proton exchange membrane in turn by the spraying method until the Pt loading of the catalyst reaches 0.1mg / cm 2 ; to obtain a catalyst layer with a gradient (CCM).

[0090] The method for making the membrane electrode is to fix the JNTG gas diffusion layer on the surface of the cathode layer and the anode layer of the CCM by hot pressing.

[0091] Example two

[0092] Step one: preparation of a CeO2 carrier

[0093] S1. Dissolve cerium nitrate hexahydrate in deionized water to obtain a metal ion solution;

[0094] The metal ion solution with a cerium metal ion concentration of 0.1mol / L, 0.3mol / L, 0.5mol / L and 0.7mol / L is configured by the above method;

[0095] S2. 10% ammonia water is used as a precipitant and added dropwise into the metal ion solution until a stable and uniform solution is formed, then stirred by an electric mixer for 12h, placed in a refrigerator for 12h, then the metal ion solution is placed in a centrifuge for centrifugal precipitation at a centrifugal speed of 4000r / min for 10min, the precipitate is collected, then the obtained precipitate is washed by ethanol and deionized water, and then the washed precipitate is placed in a tubular furnace for calcination, the calcination temperature is 400℃ and the calcination time is 40min to obtain a CeO2 carrier.

[0096] The CeO2 carriers numbered as C-A, C-B, C-C and C-D are prepared by the above metal ion solutions with a cerium metal ion concentration of 0.1mol / L, 0.3mol / L, 0.5mol / L and 0.7mol / L respectively, and the particle sizes of the CeO2 carriers with different numbers are different.

[0097] Step two: Preparation of IrO2-Pt / CeO2 catalyst and Pt / CeO2 catalyst

[0098] S1. Pour sodium citrate solid into a 50ml beaker, then add 10ml ethylene glycol (EG) to completely dissolve the sodium citrate solid, then dissolve 1g H2PtCl6.6H2O in 50ml ethylene glycol, wherein the molar ratio of sodium citrate to Pt is 2.5:1. Add 400mg CeO2 support to the above ethylene glycol solution containing H2PtCl6, ultrasonic for 0.5h, then stir for 0.5h to obtain a reaction solution, then adjust the pH of the reaction solution to 9 with a 5wt% KOH / EG solution;

[0099] S2. Put the pH-adjusted reaction solution into a sealed high-pressure reaction kettle and react at 120℃ for 6h to obtain a yellow transparent solution, then perform standing cooling treatment on the yellow transparent solution, then drop 5% HNO3 aqueous solution into the yellow transparent solution until the pH of the yellow transparent solution is less than 5, then perform ultrasonic for 15min, then perform filtration and collect the obtained powder, then put the obtained powder into a vacuum oven for drying for 12h to obtain a Pt / CeO2 catalyst;

[0100] Wherein, by adding CeO2 supports numbered C-A, C-B, C-C and C-D in the S1 process of step two, Pt / CeO2 catalysts numbered PC-A, PC-B, PC-C and PC-D can be obtained respectively;

[0101] S3. Put the Pt / CeO2 catalyst obtained in the above step and 1wt% IrO2 into a ball mill and mix for 3h to obtain an IrO2-Pt / CeO2 catalyst.

[0102] Wherein, by adding Pt / CeO2 catalysts numbered PC-A, PC-B, PC-C and PC-D in the S3 process of step two, IrO2-Pt / CeO2 catalysts numbered PCI-A, PCI-B, PCI-C and PCI-D can be obtained respectively.

[0103] Step three: Preparation of catalyst slurry

[0104] S1. Weigh PCI-A catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol according to the mass ratio of 1:40:30:90 and mix them together, disperse by ball milling for 3h, then disperse by high-speed shearing machine for 30min to form a catalyst slurry numbered An.A;

[0105] PCI-B catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed in a mass ratio of 1:35:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered An.B;

[0106] PCI-C catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed in a mass ratio of 1:30:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered An.C;

[0107] PCI-D catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed in a mass ratio of 1:25:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered An.D.

[0108] An.A, An.B, An.C and An.D catalyst slurries are anode catalyst slurries.

[0109] S1. PC-A catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed in a mass ratio of 1:40:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered Ca.A;

[0110] PC-B catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed in a mass ratio of 1:35:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered Ca.B;

[0111] PC-C catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed in a mass ratio of 1:30:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered Ca.C;

[0112] PC-D catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed in a mass ratio of 1:25:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered Ca.D.

[0113] Ca.A, Ca.B, Ca.C and Ca.D catalyst slurries are cathode catalyst slurries.

[0114] Step four: preparation of a gradient catalyst layer

[0115] Ca.A, Ca.B, Ca.C and Ca.D were sprayed onto the surface of the proton exchange membrane in turn by spraying method until the Pt loading of the catalyst layer reached 0.4 mg / cm 2 After drying, An.A, An.B, An.C and An.D slurry were sprayed onto the other surface of the proton exchange membrane in turn by spraying method until the Pt loading of the catalyst reached 0.1 mg / cm 2 to obtain a CCM with gradient catalyst layer.

[0116] The method for preparing the membrane electrode is to fix the JNTG gas diffusion layer on the surface of the cathode layer and the anode layer of the CCM by hot pressing.

[0117] Example Three

[0118] Step One: Preparation of TiO2-SnO2 carrier

[0119] S1. Dissolve titanium tetrachloride and SnCl4·5H2O in deionized water to obtain a metal ion solution, and the molar ratio of Sn and Ti ions in the metal ion solution is 1:1;

[0120] The metal ion solution with Sn metal ion concentration of 0.1 mol / L, 0.3 mol / L, 0.5 mol / L and 0.7 mol / L was configured by the above method;

[0121] S2. 10% ammonia water was used as a precipitant and added dropwise into the metal ion solution until a stable and uniform solution was formed, and then stirred by an electric mixer for 12 h, and placed in a refrigerator for aging for 12 h. Subsequently, the metal ion solution was placed in a centrifuge and centrifuged at a centrifugal speed of 4000 r / min for 10 min, and the precipitate was collected. Then the obtained precipitate was washed with ethanol and deionized water, and then the washed precipitate was placed in a tube furnace for calcination, and the calcination temperature was 400℃ and the calcination time was 40 min, to obtain a TiO2-SnO2 carrier.

[0122] The TiO2-SnO2 carriers numbered TS-A, TS-B, TS-TS and TS-D were prepared by the above metal ion solutions with Sn metal ion concentration of 0.1 mol / L, 0.3 mol / L, 0.5 mol / L and 0.7 mol / L respectively, and the particle sizes of the TiO2-SnO2 carriers with different numbers were different.

[0123] Step Two: Preparation of IrO2-Pt / TiO2-SnO2 catalyst and Pt / TiO2-SnO2 catalyst

[0124] S1. Pour sodium citrate solid into a 50ml beaker, then add 10ml ethylene glycol (EG) to completely dissolve the sodium citrate solid, then dissolve 1g H2PtCl6.6H2O in 50ml ethylene glycol, wherein the molar ratio of sodium citrate to Pt is 2.5:1. Add 400mg TiO2-SnO2 carrier to the above ethylene glycol solution containing H2PtCl6, ultrasonic for 0.5h, then stir for 0.5h to obtain a reaction solution, then adjust the pH of the reaction solution to 9 with a 5wt% KOH / EG solution;

[0125] S2. Put the pH-adjusted reaction solution into a sealed high-pressure reaction kettle and react at 120℃ for 6h to obtain a yellow transparent solution, then perform a standing cooling treatment on the yellow transparent solution, then drop 5% HNO3 aqueous solution into the yellow transparent solution until the pH of the yellow transparent solution is less than 5, then perform ultrasonic for 15min, then perform filtration and collect the obtained powder, then put the obtained powder into a vacuum oven to dry for 12h to obtain a Pt / TiO2-SnO2 catalyst;

[0126] In the S1 process of step two, by adding TSeO2 carriers numbered TS-A, TS-B, TS-TS and TS-D, PTS / TSeO2 catalysts numbered PTS-A, PTS-B, PTS-TS and PTS-D can be obtained, respectively;

[0127] S3. Put the Pt / TiO2-SnO2 catalyst obtained in the above step and 1wt% IrO2 into a ball mill and mix and disperse for 3h to obtain an IrO2-Pt / TiO2-SnO2 catalyst.

[0128] In the S3 process of step two, by adding Pt / TiO2-SnO2 catalysts numbered PTS-A, PTS-B, PTS-TS and PTS-D, IrO2-Pt / TiO2-SnO2 catalysts numbered PTSI-A, PTSI-B, PTSI-TS and PTSI-D can be obtained, respectively.

[0129] Step three: preparation of catalyst slurry

[0130] S1. Weigh PTSI-A catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol in a mass ratio of 1:40:30:90 and mix them together, disperse by ball milling for 3h and mix uniformly, then disperse by a high-speed shearing machine for 30min to form a catalyst slurry numbered An.A;

[0131] PTS1-B catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed according to the mass ratio of 1:35:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered as An.B;

[0132] PTS1-C catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed according to the mass ratio of 1:30:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered as An.C;

[0133] PTS1-D catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed according to the mass ratio of 1:25:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered as An.D.

[0134] An.A, An.B, An.C and An.D catalyst slurries are anode catalyst slurries.

[0135] S1. PTS-A catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed according to the mass ratio of 1:40:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered as Ca.A;

[0136] PTS-B catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed according to the mass ratio of 1:35:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered as Ca.B;

[0137] PTS-C catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed according to the mass ratio of 1:30:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered as Ca.C;

[0138] PTS-D catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol were weighed according to the mass ratio of 1:25:30:90, mixed together, dispersed by ball milling for 3h and mixed uniformly, then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered as Ca.D.

[0139] Ca.A, Ca.B, Ca.C and Ca.D catalyst slurries are cathode catalyst slurries.

[0140] Step four: preparation of a gradient catalyst layer

[0141] Ca.A, Ca.B, Ca.C and Ca.D were sprayed onto the surface of the proton exchange membrane in turn by spraying method until the Pt loading of the catalyst layer reached 0.4 mg / cm 2 After drying, An.A, An.B, An.C and An.D slurry were sprayed onto the other surface of the proton exchange membrane in turn by spraying method until the Pt loading of the catalyst reached 0.1 mg / cm 2 , to obtain a gradient catalyst layer (CCM).

[0142] The method for preparing the membrane electrode is to fix the JNTG gas diffusion layer on the surface of the cathode layer and the anode layer of the CCM by hot pressing.

[0143] Comparative Example 1

[0144] Step one: preparation of IrO2-Pt / C catalyst and Pt / C catalyst

[0145] The Pt / C catalyst and 1wt% IrO2 were mixed and dispersed in a ball mill for 3h to obtain an IrO2-Pt / C catalyst.

[0146] Step three: preparation of catalyst slurry

[0147] S1. IrO2-Pt / C, perfluorosulfonic acid ionomer, ultrapure water and isopropanol were weighed according to the mass ratio of 1:30:30:90 and mixed together, uniformly dispersed by ball milling for 3h, and then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered An.0;

[0148] S2. Pt / C, perfluorosulfonic acid ionomer, ultrapure water and isopropanol were weighed according to the mass ratio of 1:30:30:90 and mixed together, uniformly dispersed by ball milling for 3h, and then dispersed by a high-speed shearing machine for 30min to form a catalyst slurry numbered Ca.0;

[0149] Step four: preparation of gradient catalyst layer

[0150] Ca.0 was sprayed onto the surface of the proton exchange membrane by spraying method until the Pt loading of the catalyst layer reached 0.4 mg / cm 2 After drying, An.0 slurry was sprayed onto the other surface of the proton exchange membrane by spraying method until the Pt loading of the catalyst reached 0.1 mg / cm 2 , to obtain a gradient catalyst layer (CCM).

[0151] The method for preparing the membrane electrode is to fix the JNTG gas diffusion layer on the surface of the cathode layer and the anode layer of the CCM by hot pressing.

[0152] The above-described embodiments are merely preferred embodiments of the present application, and cannot be used to limit the protection scope of the present application, and any non-essential changes and modifications made by those skilled in the art on the basis of the present application shall fall within the protection scope of the present application.

Claims

1. A fuel cell microporous catalytic layer for space power supply, comprising an anode catalyst slurry and a cathode catalyst slurry, characterized in that: the cathode catalyst slurry comprises a Pt / metal oxide catalyst, a perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol; the anode catalyst slurry comprises an IrO 2-Pt / metal oxide catalyst, a perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol; the IrO 2-Pt / metal oxide catalyst comprises a metal oxide carrier and IrO 2, and the surface of the metal oxide carrier carries Pt nanoparticles; the particle sizes of the Pt / metal oxide catalyst and the IrO 2-Pt / metal oxide catalyst in the catalytic layer are gradiently distributed; the mass ratio of the perfluorosulfonic acid ionomer to the metal oxide carrier in the catalytic layer is gradiently distributed, and the mass ratio of the perfluorosulfonic acid ionomer to the ultrapure water and the isopropyl alcohol is constant; the particle size of the Pt / metal oxide catalyst is 10-200 nm; and the mass ratio of the perfluorosulfonic acid ionomer to the metal oxide carrier is 0.6-1.

5. 2.The fuel cell microporous catalytic layer according to claim 1, comprising the following steps: Step 1: preparing a metal oxide carrier S1.preparing a metal ion solution, and then adding ionized water to the metal ion solution until the concentration of the metal ions in the metal ion solution is 0.1-1 mol / L; S2.adopting an alkali solution as a precipitant, and dropping it into the metal ion solution until the metal ions in the solution are completely precipitated, and then performing filtration, washing and collecting the obtained precipitate, and then performing thermal decomposition on the collected precipitate to obtain the metal oxide carrier; Step 2: preparing a Pt / metal oxide catalyst and an IrO 2-Pt / metal oxide catalyst S1.respectively weighing the metal oxide carrier, a platinum precursor, a reducing agent and a solvent, uniformly mixing the platinum precursor, the reducing agent and the solvent to obtain a mixed solution, adding the metal oxide carrier into the mixed solution, then stirring for 30 min, and then performing ultrasonic treatment for 30 min to obtain a reaction solution, and then adding an alkali solution to the reaction solution until the pH of the reaction solution is 9; S2.placing the reaction solution with the adjusted pH in a sealed high-pressure reaction kettle and reacting at 120℃ for 6 h to obtain a yellow transparent solution, then performing standing cooling treatment on the yellow transparent solution, then dropping 5% HNO 3 aqueous solution into the yellow transparent solution until the pH of the yellow transparent solution is less than 5, then performing ultrasonic treatment for 15 min, then performing filtration and collecting the obtained powder, and then drying the obtained powder in a vacuum oven for 12 h to obtain the Pt / metal oxide catalyst; S3.mixing the Pt / metal oxide catalyst and IrO 2 in a ball mill to obtain the IrO 2-Pt / metal oxide catalyst, and the particle size of the Pt / metal oxide catalyst is 10 nm-1 μm; Step 3: preparing a catalyst slurry S1.weighing the IrO 2-Pt / metal oxide catalyst, a perfluorosulfonic acid ionomer, ultrapure water and isopropyl alcohol and uniformly mixing them to form an anode catalyst slurry. ​ ​ 2. The micro-porous catalytic layer for a fuel cell for a space power supply according to claim 1, wherein ​ 3. The micro-porous catalytic layer for a fuel cell for a space power supply according to claim 1, wherein ​ 4. A method for producing a micro-porous catalytic layer for a fuel cell power source as claimed in any one of claims 1 to 3, characterized by, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ S2. Pt / metal oxide catalyst, perfluorosulfonic acid ionomer, ultrapure water and isopropanol are weighed and mixed uniformly to form a cathode catalyst slurry; Step four: preparation of gradient catalytic layer The anode catalyst slurry is sprayed to the surface of the proton exchange membrane, wherein the ratio of IrO2-Pt / metal oxide catalyst, ultrapure water and isopropanol is unchanged, the particle size of IrO2-Pt / metal oxide catalyst increases along the direction away from the proton exchange membrane, and the mass ratio of perfluorosulfonic acid ionomer to metal oxide carrier decreases. The cathode catalyst slurry is sprayed to the other side of the surface of the proton exchange membrane, wherein the ratio of Pt / metal oxide catalyst, ultrapure water and isopropanol is unchanged, the particle size of IrO2-Pt / metal oxide catalyst increases along the direction away from the proton exchange membrane, and the mass ratio of perfluorosulfonic acid ionomer to metal oxide carrier decreases.

5. The method for preparing a micro-porous catalyst layer for a fuel cell for a space power supply according to claim 4, characterized by, The metal oxide precursor in step one is one or more of cerium salt solution, titanium salt solution and zirconium salt solution.

6. The method for preparing a microporous catalyst layer for a space power fuel cell according to claim 4, characterized in that, The platinum precursor in step two is one or more of chloroplatinic acid, tetraammine platinum nitrate and phthalocyanine platinum.

7. A membrane electrode for a fuel cell for space power supply, comprising a proton exchange membrane, a gas diffusion layer, and a catalyst layer, the catalyst layer being the microporous catalyst layer for a fuel cell for space power supply according to any one of claims 1 to 3, the thickness of the catalyst layer being 500 nm to 20 μm, and the catalyst loading in the catalyst layer being 0.05 to 0.5 mg / cm 2 .

8. A fuel cell for space power supply, characterized by comprising: The membrane electrode of claim 7 is included.

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