A proton exchange membrane fuel cell alloy catalyst and its preparation method

Abstract

The present invention provides a proton exchange membrane fuel cell alloy catalyst and a preparation method thereof. The preparation method comprises the following steps: (1) thoroughly mixing a noble metal solution, a non-noble metal solution, and a carrier material, adding an additive to the mixed solution, removing part of the solvent, and forming an alloy precursor having a liquid content of 75% to 99.5%; (2) transferring the alloy precursor into a calcination device, raising the temperature to 60 to 120° C. and maintaining the temperature until the water content is less than 2000 ppm in the calcination device, and then raising the temperature to 400 to 900° C. and performing high-temperature calcination for 0.5 to 8 hours. During the calcination process, the oxygen and water contents are strictly controlled, and an inert gas is continuously introduced during the alloying process; (3) dispersing the alloyed material with water, adding a treatment liquid, filtering, washing, and drying after treatment to obtain the alloy catalyst. The alloy catalyst prepared by the preparation method of the present invention can improve the stability of the alloying, improve the performance of the single cell, and effectively reduce the preparation steps of the alloy catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a proton exchange membrane fuel cell alloy catalyst and a preparation method thereof. Background Art

[0002] Fuel cells convert chemical energy into electrical energy through electrochemical reactions. They offer significant advantages, including low carbon emissions, environmental friendliness, high energy efficiency, and stability and reliability. They hold great promise for applications in aerospace, automotive, and smart devices. Fuel cells deliver fuel (hydrogen, methanol, etc.) to the anode and oxidant (air or oxygen) to the cathode. An electrolyte separates the two electrodes, and catalysts accelerate the electrochemical reactions at the cathode and cathode, efficiently converting chemical energy into electrical energy.

[0003] Catalysts are key to efficient energy conversion in fuel cells, and high-performance catalysts have long been a research focus. Currently, commonly used fuel cell catalysts are made by dispersing precious metals such as platinum on carriers with ultra-high specific surface areas. Using inexpensive non-precious metals to form alloys with precious metals is an effective means of reducing fuel cell costs. The alloying method of the precious metals and non-precious metals is crucial, as the alloying process directly impacts catalyst performance. Existing alloying technologies, due to lax atmosphere control, result in unstable product performance and low precious metal utilization. Therefore, improving alloying stability is crucial for product performance. Summary of the Invention

[0004] The present invention aims to overcome the shortcomings of the prior art by providing a proton exchange membrane fuel cell alloy catalyst and its preparation method. The alloy catalyst prepared by the present invention improves alloying stability and single cell performance, while also effectively reducing the number of steps required to prepare the alloy catalyst. The alloying method is stable and reliable, and has the potential for industrial scalability.

[0005] To achieve the above technical objectives, the technical solution adopted in the embodiment of the present invention is:

[0006] In a first aspect, an embodiment of the present invention provides a method for preparing a proton exchange membrane fuel cell alloy catalyst, comprising the following steps:

[0007] (1) The noble metal solution, the non-noble metal solution and the carrier material are fully mixed, an additive is added to the mixed solution, and 5%-50% of the solvent is removed to form an alloy precursor with a liquid content of 75%-99.5%;

[0008] (2) Alloying: The alloy precursor is moved into a roasting device, and an inert gas is introduced after the airtightness meets the requirements. When the oxygen content in the roasting device is less than 1000 ppm, the temperature is raised to 60-120°C and kept warm until the water content is less than 2000 ppm. The temperature is then raised to 400-900°C for high-temperature roasting for 0.5-8 hours. The oxygen and water content are strictly controlled during the roasting process, and the inert gas is continuously introduced during the alloying process.

[0009] (3) The alloyed material is dispersed with water and then added with treatment liquid. After treatment, it is filtered, washed, and dried to obtain the alloy catalyst.

[0010] Furthermore, the concentration of the noble metal solution in step (1) is 0.001-10 mol / L, and the noble metal element in the solution is one or more of ruthenium, rhodium, palladium, osmium, iridium and platinum.

[0011] Furthermore, the concentration of the non-precious metal solution in step (1) is 0.005-9 mol / L, and the non-precious metal elements in the solution are one or more of iron, cobalt, nickel, zinc, copper, scandium, titanium and aluminum.

[0012] Furthermore, the carrier material in step (1) is one or more of activated carbon, acetylene black, conductive carbon black, graphene, titanium oxide and tin oxide, and the specific surface area of the carrier material is 50-1800 m 2 / g.

[0013] Furthermore, the auxiliary agent in step (1) is a mixture of one or more of sodium bicarbonate, sodium hypophosphite, sodium sulfite, sodium hydroxide, aqueous ammonia, and sodium carbonate, and the molar ratio of the auxiliary agent to the metal element is 0.1-100:1, wherein the molar number of the metal element is the sum of the molar numbers of the precious metal and the non-precious metal elements, and the molar ratio of the precious metal to the non-precious metal is 0.1-10. Preferably, the molar ratio of the precious metal to the non-precious metal is 1-10.

[0014] Furthermore, the air tightness of the roasting device in step (2) meets the following conditions: the material is kept under pressure of 1 bar gauge compressed air for 10 hours, and the pressure drop is less than 500 Pa.

[0015] Furthermore, the roasting device in step (2) has an atmosphere monitoring system, which can monitor the content of hydrogen, oxygen and water, and control the hydrogen content to 0-50000ppm, the oxygen content to 0-100ppm and the water content to 0-2000ppm during the roasting process.

[0016] Furthermore, the roasting device in step (2) has a drainage system, which can condense the solvent-containing vapor released by the alloy precursor during the drying process and discharge it through the drainage system. The mass of the discharged solvent is 0.01-5 kg.

[0017] Furthermore, the treatment liquid in step (3) is a mixture of one or more of acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and citric acid, the mixture is a mixture of aqueous solutions or a mixture of the above substances, and the concentration of the treatment liquid is 0.01-4 mol / L.

[0018] In a second aspect, an embodiment of the present invention provides a proton exchange membrane fuel cell alloy catalyst prepared using the above-mentioned preparation method.

[0019] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0020] 1. The preparation process of the fuel cell alloy catalyst described in the present invention is simple, which can streamline the process and combine the drying and calcination processes into one. The alloying process of the alloy catalyst can be completed after one calcination, which makes it easier to scale up the process and achieve commercialization.

[0021] 2. The preparation method of the present invention reduces the transfer step of the alloy precursor, improves the final yield of the alloy catalyst, and thus reduces the cost of the catalyst; the drying process is carried out under a protective atmosphere, the oxygen content of the system is lower, and the alloying stability of the alloy catalyst is improved.

[0022] 3. The fuel cell alloy catalyst prepared by the present invention has good oxygen reduction performance, with a half-wave potential of more than 0.925V and a current density of 2.1A / cm at 0.65V. 2 , it has high discharge capacity when used on single batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 3 is a comparison diagram of the XRD curves of the alloy catalysts prepared in Example 2 and Comparative Example 1 of the present invention.

[0024] Figure 2 This is a comparison chart of the oxygen reduction performance of the catalysts prepared in Example 4 of the present invention and Comparative Example 2.

[0025] Figure 2 The oxygen reduction performance test was conducted in the presence of oxygen-saturated 0.1 mol / L HClO4 electrolyte; rotation speed: 1600 rpm; scan rate: 10 mVs -1 .

[0026] Figure 3 It is a comparison chart of polarization curves of the alloy catalysts prepared in Example 7 of the present invention and Comparative Example 3 when applied to a single cell test.

[0027] Figure 4 This is a comparison chart of polarization curves of the alloy catalysts prepared in Example 2 and Comparative Example 4 of the present invention when tested on a single cell.

[0028] Figure 3 and 4 The test conditions for the single cell in the test are: the active area of the battery is 20cm 2 , temperature is 80℃, stoichiometric ratio anode / cathode is 1.5 / 2.5, anode pressure is 1.6 bar, cathode pressure is 1.5 bar, anode dew point is 70℃, cathode dew point is 70℃. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] Example 1

[0031] A method for preparing a proton exchange membrane fuel cell alloy catalyst comprises the following steps:

[0032] (1) 1 L of 1 mol / L platinum tetrachloride aqueous solution, 4 L of 0.1 mol / L copper chloride aqueous solution and 196 g of Cabot Vulcan XC-72R activated carbon powder were mixed and sheared and dispersed for 1 h to form a uniform slurry; 200 g of sodium hydroxide was added at 50 ° C under stirring conditions, stirred for 30 min, and naturally settled for 20 h to remove the upper layer of water to obtain an alloy precursor with a liquid content of 80%; the liquid content refers to the ratio between the solvent in the wet material and the total material mass.

[0033] (2) The alloy precursor is transferred into a quartz boat and placed in a roasting device. After sealing, nitrogen is introduced. The atmosphere monitoring system of the roasting device is used for monitoring. When the oxygen content is less than 1000 ppm, the temperature is raised to 120°C and kept warm until the water content is less than 2000 ppm. The temperature is raised to 700°C for high-temperature roasting for 2 hours. During the roasting process at 700°C, nitrogen is continuously introduced and the ratio is controlled by a mass flow controller so that the hydrogen content is 0-50000 ppm, the oxygen content is 0-50 ppm, and the water content is 0-2000 ppm during the roasting process.

[0034] (3) After the calcined material in step (2) is naturally cooled, 5 L of water is added for shear dispersion for 1 h, 1 L of 0.5 mol / L sulfuric acid solution is added, and the mixture is stirred at 40°C for 2 h, filtered and washed, and dried at 70°C to obtain the alloy catalyst.

[0035] Single cell fabrication: Accurately weigh 200mg of the prepared alloy catalyst; add 20mL of pure water, 20mL of isopropyl alcohol, and 2mL of perfluorosulfonic acid resin solution to the alloy catalyst. Pulverize the cells for 45 minutes to form a catalyst ink, which is then evenly coated on a pre-cut proton exchange membrane (denoted as the cathode). Similarly, weigh a Johnson Matthey JM9100 catalyst and coat the resulting catalyst ink on the other side of the proton exchange membrane (denoted as the anode), forming the membrane electrode. A Freudenberg H24CX483 GDL is used as the gas diffusion layer. Disassemble the balticFuelCells QCF25 quick assembly test fixture, insert the thickness limiter, the first GDL, the CCM, and the second GDL in sequence, secure them, and rotate the pneumatic button to complete the clamping. After connecting the gas lines and performing a leak test, perform single cell testing.

[0036] Single cell test conditions: single cell area 20cm 2 The stoichiometric ratio of anode to cathode is 1.5:2.5, the anode dew point is set to 70°C, the cathode dew point is 70°C, the anode stack pressure is 1.6 bar, the cathode stack pressure is 1.5 bar, and the battery test temperature is 80°C.

[0037] Example 2

[0038] A method for preparing a proton exchange membrane fuel cell alloy catalyst comprises the following steps:

[0039] (1) 0.5 L of 1 mol / L chloroplatinic acid aqueous solution, 2 L of 0.1 mol / L cobalt chloride aqueous solution and 98 g of Cabot Vulcan XC-72R activated carbon powder were mixed and sheared and dispersed for 1 h to form a uniform slurry; 96 g of sodium hydroxide was added under stirring at 50 °C, stirred for 30 min, and allowed to settle naturally for 20 h to remove the upper layer of water to obtain an alloy precursor;

[0040] The calcination process, calcination apparatus, subsequent treatment steps and proportions of the alloy precursor were all consistent with the relevant parameters in Example 1. The method for making a single cell using the alloy catalyst prepared in this example and the test conditions were the same as those in Example 1.

[0041] Example 3

[0042] A method for preparing a proton exchange membrane fuel cell alloy catalyst. The difference between this embodiment and embodiment 1 is that 196g of titanium oxide is weighed to replace the activated carbon powder, and other proportions and conditions remain unchanged.

[0043] Example 4

[0044] A method for preparing a proton exchange membrane fuel cell alloy catalyst. The difference between this embodiment and Example 1 is that the precious metal solution is 1 L of a 1 mol / L aqueous solution of platinum tetrachloride and 0.05 L of a 0.1 mol / L palladium nitrate solution, and other proportions and conditions remain unchanged.

[0045] Example 5

[0046] A method for preparing a proton exchange membrane fuel cell alloy catalyst. The difference between this embodiment and Example 2 is that the precious metal solution comprises 1 L of a 1 mol / L aqueous solution of platinum tetrachloride and 0.1 L of a 0.06 mol / L chloroiridic acid solution. The liquid content of the alloy precursor is controlled at 75%, and other proportions and conditions remain unchanged.

[0047] Example 6

[0048] A method for preparing a proton exchange membrane fuel cell alloy catalyst. The difference between this embodiment and Example 3 is that the precious metal solution is: 1L of a 1 mol / L platinum tetrachloride aqueous solution and 0.1L of a 0.06 mol / L ruthenium chloride solution; the non-metallic solution is: 4L of a 0.1 mol / L copper chloride aqueous solution and 0.1L of a 0.2 mol / L nickel nitrate solution; the liquid content of the alloy precursor is controlled at 98%, and other proportions and conditions remain unchanged.

[0049] Example 7

[0050] A method for preparing a proton exchange membrane fuel cell alloy catalyst. The difference between this embodiment and Example 4 is that the non-metallic solution is: 4 L of a 0.1 mol / L copper chloride aqueous solution and 0.2 L of a 0.04 mol / L titanium trichloride solution. The liquid content of the alloy precursor is controlled at 80%, the hydrogen content during calcination is 0 ppm, and other proportions and conditions remain unchanged.

[0051] Comparative Example 1

[0052] A method for preparing a proton exchange membrane fuel cell alloy catalyst. The difference between this comparative example and Example 2 is that the roasting device used in the roasting process of step (2) is a Hefei Kejing OTF-1200X-5L 1200°C extended open tube furnace, and the device has no atmosphere detection system. The initial measurement values before roasting measured using a micro-oxygen analyzer and a dew point meter are: oxygen content 370ppm, water content 4300ppm, and other conditions are the same as in Example 2.

[0053] Comparative Example 2

[0054] A method for preparing a proton exchange membrane fuel cell alloy catalyst. The difference between this comparative example and Example 4 is that the roasting device used in the roasting process of step (2) is a Hefei Kejing OTF-1200X-5L 1200°C extended open tube furnace. The device has no atmosphere detection system. The initial measurement values before roasting measured using a micro-oxygen analyzer and a dew point meter are: oxygen content 330ppm, water content 3200ppm, and other conditions are the same as in Example 2.

[0055] Comparative Example 3

[0056] A method for preparing a proton exchange membrane fuel cell alloy catalyst. The difference between this comparative example and Example 7 is that the roasting device used in the roasting process of step (2) is a Hefei Kejing OTF-1200X-5L 1200°C extended open tube furnace. The device has no atmosphere detection system. The initial measurement values before roasting measured using a micro-oxygen analyzer and a dew point meter are: oxygen content 280ppm, water content 2700ppm, and other conditions are the same as in Example 7.

[0057] Comparative Example 4

[0058] A method for preparing a proton exchange membrane fuel cell alloy catalyst. The difference between this comparative example and Example 2 is that a gas mass flow controller is used to control the ratio so that the introduced atmosphere contains 10,000 ppm of oxygen, and other conditions remain the same as in Example 2.

[0059] from Figure 1 It can be seen from the XRD curves of Example 2 and Comparative Example 1 that when the test conditions are the same, the strength of the alloy catalyst prepared in Example 2 is higher, indicating that the alloying degree of the alloy catalyst prepared in the present invention is higher and the alloying method is better.

[0060] from Figure 2 It can be seen that when the alloy catalysts prepared using Example 4 and Comparative Example 2 are at the same voltage, the current density of Example 4 is higher, and the half-wave potential can reach above 0.925 V, indicating that the alloy catalyst of the present invention has good performance.

[0061] from Figure 3 and Figure 4 It can be seen that the current density of the fuel cell single cell made by using the alloy catalyst prepared by the present invention can reach 2.1A / cm 2 , the current density is greatly improved under the same voltage.

[0062] In summary, the alloy catalyst prepared by the preparation method of the present invention has high catalytic activity, and the single cell prepared using the catalyst has good performance.

[0063] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a proton exchange membrane fuel cell alloy catalyst, characterized in that: The following steps are involved: (1) The noble metal solution, the non-noble metal solution and the carrier material are fully mixed, an additive is added to the mixed solution, and 5%-50% of the solvent is removed to form an alloy precursor with a liquid content of 75%-99.5%; (2) Alloying: The alloy precursor is moved into a roasting device, and an inert gas is introduced after the airtightness meets the requirements. When the oxygen content in the roasting device is less than 1000 ppm, the temperature is raised to 60-120°C and kept warm until the water content is less than 2000 ppm. The temperature is then raised to 400-900°C for high-temperature roasting for 0.5-8 hours. The oxygen and water content are strictly controlled during the roasting process, and the inert gas is continuously introduced during the alloying process. (3) The alloyed material is dispersed with water and then added with treatment liquid. After treatment, it is filtered, washed, and dried to obtain the alloy catalyst; The concentration of the noble metal solution in step (1) is 0.001-10 mol / L, and the noble metal element in the solution is one or more of ruthenium, rhodium, palladium, osmium, iridium and platinum; The concentration of the non-precious metal solution in step (1) is 0.005-9 mol / L, and the non-precious metal elements in the solution are one or more of iron, cobalt, nickel, zinc, copper, scandium, titanium and aluminum; The auxiliary agent in step (1) is a mixture of one or more of sodium bicarbonate, sodium hypophosphite, sodium sulfite, sodium hydroxide, ammonia water and sodium carbonate, and the molar ratio of the auxiliary agent to the metal element is 0.1-100:1, wherein the molar number of the metal element is the sum of the molar numbers of the noble metal and the non-noble metal elements, and the molar ratio of the noble metal to the non-noble metal is 0.1-10; The roasting device in step (2) has an atmosphere monitoring system, which can monitor the content of hydrogen, oxygen and water, and control the hydrogen content to 0-50000ppm, the oxygen content to 0-100ppm and the water content to 0-2000ppm during the roasting process; The roasting device in step (2) has a drainage system, which can condense the solvent-containing vapor released by the alloy precursor during the drying process and discharge it through the drainage system; The air tightness of the roasting device in step (2) meets the following conditions: the material is kept under 1 bar gauge compressed air pressure for 10 hours, and the pressure drop is less than 500 Pa.

2. The method for preparing a proton exchange membrane fuel cell alloy catalyst according to claim 1, wherein: The carrier material in step (1) is one or more of activated carbon, conductive carbon black, graphene, titanium oxide and tin oxide, and the specific surface area of the carrier material is 50-1800 m 2 / g.

3. The method for preparing a proton exchange membrane fuel cell alloy catalyst according to claim 1, wherein: The carrier material in step (1) is acetylene black.

4. The method for preparing a proton exchange membrane fuel cell alloy catalyst according to claim 1, wherein: The treatment liquid in step (3) is a mixture of one or more of acetic acid, hydrochloric acid, nitric acid, sulfuric acid, hydrogen peroxide and citric acid, the mixture is a mixture of aqueous solutions or a mixture of the above substances, and the concentration of the treatment liquid is 0.01-4 mol / L.

5. A proton exchange membrane fuel cell alloy catalyst, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 4.

Images