Preparation method and device of carbon pore anchored nanoparticle fuel cell catalyst

Abstract

The invention discloses a preparation method and device of a carbon pore anchored nanoparticle fuel cell catalyst, and belongs to the technical field of catalyst preparation. The method comprises the following steps: (1) heating porous carbon powder under a negative pressure condition, and cooling to obtain a carbon carrier; (2) adding a metal precursor solution into the carbon carrier, sequentially carrying out ultrasonic treatment and stirring treatment under a negative pressure condition, then introducing inert gas to form a positive pressure environment, and sequentially carrying out ultrasonic treatment and stirring treatment again; (3) keeping a positive pressure environment formed by the inert gas, heating the mixed substance, and stirring at the same time, so that the mixed substance reacts to obtain catalyst slurry; and (4) carrying out solid-liquid separation on the catalyst slurry to obtain catalyst particles, and then sequentially carrying out cleaning, vacuum drying, grinding and vacuum heat treatment on the catalyst particles to obtain the carbon pore anchored nanoparticle fuel cell catalyst. According to the invention, the catalytic activity and durability of the catalyst are improved by preparing the carbon pore anchored nanoparticle fuel cell catalyst.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cell catalyst preparation, and relates to a method and a device for preparing a carbon pore anchored nanoparticle fuel cell catalyst. Background Art

[0002] Proton exchange membrane fuel cell (PEMFC) is a device that converts the chemical energy of hydrogen and oxygen into electrical energy through electrochemical reactions. It has the characteristics of high efficiency and zero emissions. At present, proton exchange membrane fuel cells are still plagued by the slow kinetics of the cathode oxygen reduction reaction (ORR) and the deactivation of the catalyst caused by the migration, shedding and agglomeration of platinum nanoparticles in the ORR catalyst during long-term operation. There is an urgent need to develop platinum-based ORR catalysts with high activity and excellent durability. A large number of studies have shown that alloying platinum with transition metals (Co, Ni, and Fe, etc.) is the main way to improve the activity and stability of the catalyst. Transition metals alloyed with platinum can not only reduce the amount of precious metal platinum to a large extent, but also significantly improve the catalyst activity through ligand and strain effects.

[0003] At present, the main method for preparing carbon-supported platinum nanoparticle catalysts (Pt / C) or carbon-supported platinum alloy nanoparticle catalysts (PtM / C) is to stir and ultrasonically disperse porous carbon and platinum salt precursor solution or PtM precursor solution mixed with platinum salt and transition metal salt to obtain a uniformly mixed precursor slurry, and then reduce the metal ions by low-temperature and high-pressure liquid phase or high-temperature solid phase reduction method to nucleate and grow on the carbon support to prepare carbon-supported Pt or PtM nanoparticle catalysts. Although these Pt / C or PtM / C catalysts have high ORR activity, their long-term durability is poor during the long-term operation of fuel cells. The main manifestation is that when the fuel cell is operated for a long time at the normal working potential (<1.0V), the Pt or PtM nanoparticles in the catalyst are easy to migrate, fall off and agglomerate, resulting in catalyst deactivation and fuel cell performance degradation. The main reason for the poor durability of fuel cells is that the Pt or PtM nanoparticles in the catalyst are only dispersed on the surface of the porous carbon, resulting in weak interaction between the nanoparticles and the carbon carrier. As a result, during the long-term operation of the fuel cell, the Pt or PtM nanoparticles in the catalyst are easily migrated, detached and agglomerated, resulting in the degradation of the fuel cell performance, which ultimately manifests as poor durability of the fuel cell.

[0004] There are two key factors that cause the Pt or PtM nanoparticles in the catalyst to be dispersed only on the surface of porous carbon: (1) The porous carbon carrier with a high specific surface area has a strong adsorption capacity. It adsorbs a large amount of gas in the pores of the carbon carrier through physical or chemical adsorption, which hinders the metal precursor solution from entering the pores of the porous carbon carrier, so that the nucleation and growth of metal nanoparticles can only be carried out on the surface of the porous carbon carrier; (2) The surface tension of the metal precursor solution itself hinders it from immersing into the micron and nanometer-sized pores in the porous carbon carrier, so that the metal nanoparticles can only nucleate and grow on the surface of the porous carbon carrier. In addition, the conventional catalyst preparation process is carried out in an atmospheric environment. The nucleation and growth of Pt or PtM alloy nanoparticles are inevitably affected by impurity gases such as oxygen, sulfur-containing atmosphere and organic volatiles in the air, as well as ambient temperature, atmospheric pressure and humidity. This has a negative impact on the size, morphology, structure and dispersion of Pt or PtM alloy nanoparticles on the carbon carrier, making it difficult to maintain stable catalyst performance and quality.

[0005] Therefore, it is necessary to provide a method and device for preparing a carbon pore-anchored nanoparticle fuel cell catalyst, so that the Pt or PtM nanoparticles in the prepared fuel cell catalyst can enter the pores of the porous carbon carrier, reduce the migration, shedding and agglomeration of the Pt or PtM alloy nanoparticles in the catalyst during long-term electrochemical reactions, improve the durability of the fuel cell catalyst, reduce the performance attenuation rate of the fuel cell, and ensure the stability of the performance and quality of the prepared catalyst. Summary of the invention

[0006] In order to overcome the problems in the background technology, the present invention heats the carbon carrier under negative pressure conditions to promote the discharge of gas in the carbon carrier pores, provide sufficient space for Pt or PtM nanoparticles to enter the pores, then add a metal precursor solution, first perform ultrasonic and stirring treatment on the mixture of the carbon carrier and the metal precursor solution under negative pressure conditions, then introduce an inert gas for pressurization, and again perform ultrasonic and stirring treatment on the mixture of the carbon carrier and the metal precursor solution, generate a positive pressure environment by pressurizing the inert gas, and combine with the acoustic cavitation effect to overcome the surface tension of the metal precursor solution, promote the metal precursor solution to immerse in the carbon carrier pores, and make the metal ions in the carbon carrier pores in situ reduction growth to synthesize metal nanoparticles, so that in the prepared catalyst, the Pt or PtM nanoparticles enter the carbon carrier pores, enhance the interaction between the carbon carrier and the metal nanoparticles, reduce the migration, shedding and agglomeration of the Pt or PtM nanoparticles in the catalyst, improve the durability of the fuel cell catalyst, and reduce the fuel cell performance decay rate.

[0007] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0008] In one aspect, the present invention provides a method for preparing a carbon pore-anchored nanoparticle fuel cell catalyst, the preparation method comprising the following steps:

[0009] The preparation method comprises the following steps:

[0010] (1) The porous carbon powder is heated under negative pressure and then cooled to obtain a carbon carrier.

[0011] (2) Adding the metal precursor solution to the carbon support obtained in step (1), subjecting the mixture to ultrasonic and stirring treatments in sequence under negative pressure, then introducing an inert gas to form a positive pressure environment, and subjecting the mixture to ultrasonic and stirring treatments in sequence again until the mixture is uniformly dispersed. The inert gas is argon, nitrogen, etc.

[0012] (3) maintaining a positive pressure environment formed by the inert gas, heating the uniformly dispersed mixed material obtained in step (2), and stirring the mixed material, so that the mixed material reacts under the positive pressure conditions formed by the inert gas, and after the reaction is completed, obtaining a catalyst slurry.

[0013] (4) performing solid-liquid separation on the catalyst slurry obtained in step (3) to obtain catalyst particles, washing the catalyst particles with deionized water, vacuum drying the catalyst particles after washing, grinding the catalyst particles, and then vacuum heat treating the ground catalyst particles to obtain a carbon-supported nanoparticle fuel cell catalyst.

[0014] Preferably, the nanoparticles include platinum and platinum alloy nanoparticles.

[0015] Preferably, in step (1), the negative pressure is 1000 to 10 -6 Pa, the heating temperature is 75-350°C, and the temperature is kept for 60-300 minutes. After heating, it is cooled to 20-60°C to obtain a carbon carrier.

[0016] Preferably, in the step (2), the metal precursor solution is added at a rate of 2 to 100 mL / min, an inert gas is introduced to form a positive pressure environment with a pressure of 0.3 to 5 MPa, the ultrasonic frequency is 20 to 100 kHz, the ultrasonic time is 2 to 40 min, the stirring rate is 200 to 400 r / min, and the stirring time is 2 to 40 min.

[0017] Preferably, in step (3), the heating temperature is 150-250° C., the insulation time is 300-2880 min, and the stirring speed is 5-100 r / min.

[0018] Preferably, in step (4), the vacuum drying temperature is 60 to 100° C., and the grinding time is 30 to 60 min.

[0019] Preferably, in step (4), the vacuum heat treatment temperature is 150-230° C., and the vacuum heat treatment time is 120-720 min.

[0020] Preferably, the porous carbon powder comprises one of Ketjen Black EC-300J, Ketjen Black EC-600JD, acetylene carbon black, and Cabot BP2000. Further preferably, the porous carbon powder has a heating specific surface area of ​​500 to 2000 m 2 / g, the porous carbon powder has three types of pores and channels: micropores (pore diameter <2nm), mesopores (pore diameter 2-50nm), and macropores (pore diameter >50nm).

[0021] Preferably, the metal precursor solution is a platinum metal precursor solution or a platinum alloy precursor solution, the platinum metal precursor solution is prepared from a platinum salt precursor and an organic solvent, the platinum alloy precursor solution is prepared from a platinum salt precursor, a transition metal precursor, and an organic solvent, the platinum ion concentration in the platinum metal precursor solution is 0.5 to 2 g / L, and the metal ion concentration in the platinum alloy precursor solution is 0.1 to 0.6 g / L. It is further preferred that the platinum salt precursor includes one of platinum acetate, platinum acetylacetonate, chloroplatinic acid, and platinum dichloride, the transition metal precursor is one or more of cobalt acetylacetonate, cobalt nitrate, copper acetylacetonate, copper nitrate, iron acetylacetonate, iron nitrate, nickel acetylacetonate, nickel nitrate, and the like, and the organic solvent is one or more of N,N-dimethylformamide, benzene, ethanol, chloroform, carbon tetrachloride, ethylene glycol, oleylamine, oleic acid, and the like.

[0022] On the other hand, the present invention proposes a preparation device for the above-mentioned preparation method, the preparation device includes a pressure-resistant cavity 1, a reaction chamber lining 2, a stirring paddle 3, a heating element 4, a temperature measuring element 5, a heating power supply 6, a temperature control system 7, a stirring control system 8, an inert gas supercharger 9, a first valve 10, a molecular pump unit 11, a second valve 12, an ultrasonic generator 13, a transducer 14, a horn 15, a peristaltic pump 16, a third valve 17, a quartz container 18, a pressure relief valve 19, a ceramic insulated electrode 20, and a flange 21. The reaction chamber lining 2 is placed inside the pressure-resistant cavity 1, and the pressure-resistant cavity 1 is sealed by the flange 21. The stirring paddle 3 is rotatably installed on the top of the pressure-resistant cavity 1 and the stirring paddle 3 extends into the reaction chamber lining 2. The stirring paddle 3 is driven by a motor, the heating element 4 is installed at the bottom of the pressure-resistant cavity 1, and the reaction chamber lining 2 is placed on the heating element 4. The temperature measuring element 5 is sandwiched between the reaction chamber lining 2 and the heating element 4, the inert gas booster 9 is connected to the pressure chamber 1 through a pipeline, and a first valve 10 is installed on the pipeline connecting the inert gas booster 9 and the pressure chamber 1, the molecular pump unit 11 is connected to the pressure chamber 1 through a pipeline, and a second valve 12 is installed on the pipeline connecting the molecular pump unit 11 and the pressure chamber 1, the ultrasonic generator 13 is located outside the pressure chamber 1, the transducer 14 is installed in the pressure chamber 1, the horn 15 is installed on the transducer 14 and the horn 15 extends into the reaction chamber lining 2, the quartz container 18 is connected to the reaction chamber lining 2 through a pipeline, and a peristaltic pump 16 and a third valve 17 are installed on the pipeline connecting the quartz container 18 and the reaction chamber lining 2, a pressure relief valve 19 is installed on the side wall of the pressure chamber 1, and the ceramic insulating electrode 20 is embedded in the bottom flange 21 of the pressure chamber 1;

[0023] The stirring control system 8 is electrically connected to the motor, the ultrasonic generator 13 is electrically connected to the transducer 14 through the ceramic insulating electrode 20, the heating element 4 is electrically connected to the heating power supply 6 through the ceramic insulating electrode 20, the temperature measuring element 5 is electrically connected to the temperature control system 7 through the ceramic insulating electrode 20, and the temperature control system 7 is electrically connected to the heating power supply 6. Among them, the heating element 4 can use a resistance wire or a ceramic heating sheet, and the temperature measuring element 5 can use a sheet thermocouple. The reaction chamber lining 2 is SUS 304 or SUS 316 with polytetrafluoroethylene coated on the inner surface.

[0024] Beneficial effects of the present invention:

[0025] 1. The present invention discharges the gas in the pores of the carbon carrier to avoid the gas adsorbed in the pores of the carbon carrier from hindering the metal precursor solution, thereby providing sufficient space for the metal precursor solution to smoothly penetrate into the pores of the carbon carrier.

[0026] 2. The present invention creates a positive pressure environment by pressurizing an inert gas and combines the acoustic cavitation effect to overcome the surface tension of the metal precursor solution and further promote the metal precursor solution to penetrate into the pores of the carbon support.

[0027] 3. The present invention promotes the penetration of metal precursor solution into the pores of the carbon carrier, so that the metal ions are reduced and grown in situ in the pores of the carbon carrier to synthesize metal nanoparticles, thereby enhancing the interaction between the carbon carrier and the metal nanoparticles. At the same time, combined with the restraining effect of the carbon carrier pores on the metal nanoparticles, the probability of migration, shedding and agglomeration of the metal nanoparticles in the long-term electrochemical reaction process is reduced, thereby improving the durability of the catalyst and extending the service life of the fuel cell.

[0028] 4. The preparation process of the present invention is carried out in a negative pressure vacuum and an inert gas positive pressure environment to avoid the negative impact of impurity atmospheres such as oxygen, sulfur dioxide, and organic volatiles in the atmospheric environment on the performance and quality of the catalyst. It also avoids the adsorption of impurity atmospheres in the atmospheric environment into the pores of the carbon carrier, which has a negative impact on the infiltration of the metal precursor solution into the pores of the carbon carrier. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the structure of the preparation device of the present invention;

[0030] Figure 2 This is a TEM image of the catalyst prepared in Example 2 of the present invention;

[0031] Figure 3 This is a TEM image of the catalyst prepared in Comparative Example 2 of the present invention;

[0032] Figure 4 X-ray diffraction patterns of the catalysts prepared in Examples 1 and 4 of the present invention;

[0033] Figure 5 This is a bar graph of the ORR catalyst activity (MA) retention rate of the catalysts prepared in the examples of the present invention and the comparative examples after 30,000 cycles at low potential.

[0034] In the figure, 1-pressure-resistant cavity, 2-reaction chamber lining, 3-stirring paddle, 4-heating element, 5-temperature measuring element, 6-heating power supply, 7-temperature control system, 8-stirring control system, 9-inert gas booster, 10-first valve, 11-molecular pump unit, 12-second valve, 13-ultrasonic generator, 14-transducer, 15-amplifier, 16-peristaltic pump, 17-third valve, 18-quartz container, 19-pressure relief valve, 20-ceramic insulated electrode, 21-flange. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with specific embodiments.

[0036] In the examples and comparative examples of the present invention, chemical reagents not described in detail were all commercially available analytically pure reagents for experiments.

[0037] Example 1

[0038] This example uses the preparation device of the present invention to prepare a fuel cell catalyst through the following steps:

[0039] (1) The flange 21 of the pressure chamber 1 is opened, 1500 mg of porous carbon powder is added to the reaction chamber lining 2, and then the pressure chamber 1 is sealed with the flange 21. The reaction chamber lining 2 is in a sealed environment formed by the pressure chamber 1. The molecular pump unit 11 is turned on, and the second valve 12 is opened. At this time, the first valve 10, the third valve 17, the pressure relief valve 19, the peristaltic pump 16, the ultrasonic generator 13, the transducer 14, etc. are all in a closed state. The pressure chamber 1 is pumped into 10 by the molecular pump unit 11. -5 Pa negative pressure vacuum environment, the porous carbon powder is in a negative pressure vacuum environment, then the heating temperature is set to 250°C by the temperature control system 7, the temperature control system 7 controls the voltage of the heating power supply 6, so that the heating element 4 reaches a heating temperature of 250°C, the porous carbon powder is heated in the negative pressure vacuum environment, after heating for 60 minutes, the heating element 4 is controlled by the temperature control system 7 to stop heating, the porous carbon powder is cooled to 20°C in the reaction chamber lining 2, and the carbon carrier is obtained. During the heating process, the temperature measuring element 5 measures the temperature in real time and transmits the signal to the temperature control system 7, and the temperature control system 7 adjusts the heating temperature of the heating element 4 according to the temperature measured by the temperature measuring element 5 to keep the temperature relatively constant.

[0040] (2) Close the molecular pump unit 11 and the second valve 12, open the third valve 17, start the peristaltic pump 16, and control the peristaltic pump 16 to transport the metal precursor solution that has been prepared in advance and added to the quartz container 18 to the reaction chamber lining 2 at a rate of 10 mL / min. A total of 3000 mL of the metal precursor solution is transported. The metal precursor solution in this embodiment is prepared by dissolving 3000 mg of platinum acetylacetonate (platinum salt precursor) in 3000 mL of N,N-dimethylformamide solution (organic solvent), which is a platinum metal precursor solution with a platinum ion concentration of 0.5 g / L. After the metal precursor solution is added, the peristaltic pump 16 and the third valve 17 are turned on, and the ultrasonic generator 13, the transducer 14, and the amplitude transformer 15 are turned on. The ultrasonic frequency is set to 20kHz. After 2 minutes of ultrasonic dispersion treatment, the ultrasonic generator 13, the transducer 14, and the amplitude transformer 15 are turned off, and the stirring paddle 3 is controlled to start through the stirring control system 8. The stirring rate of the stirring paddle 3 is set to 300r / min. After 2 minutes of stirring treatment, the stirring paddle 3 is controlled to stop stirring through the stirring control system 8. Open the inert gas booster 9 and the first valve 10, fill the pressure-resistant chamber 1 with inert gas through the inert gas booster 9, and make the pressure in the pressure-resistant chamber 1 reach 0.3 MPa, close the inert gas booster 9 and the first valve 10, turn on the ultrasonic generator 13, the transducer 14, and the amplitude transformer 15, set the ultrasonic frequency to 20 kHz, and after 2 minutes of ultrasonic dispersion treatment, turn off the ultrasonic generator 13, the transducer 14, and the amplitude transformer 15, control the stirring paddle 3 pneumatically through the stirring control system 8 again, set the stirring rate of the stirring paddle 3 to 300 r / min, and after 2 minutes of stirring treatment, control the stirring paddle 3 to stop stirring through the stirring control system 8.

[0041] (3) The heating element 4 is controlled to be turned on by the temperature control system 7, and the heating temperature is set to 170°C. At the same time, the stirring control system 8 controls the stirring paddle 3 to stir at a rate of 5 r / min. After stirring and heating for a total of 2880 min, the catalyst slurry is obtained, the heating element 4 and the stirring paddle 3 are turned off, the pressure relief valve 19 is opened, the inert gas in the pressure-resistant chamber 1 is discharged, and the pressure in the pressure-resistant chamber 1 is balanced with the atmospheric pressure, the peristaltic pump 16 and the third valve 17 are opened, and the peristaltic pump 16 is controlled to transport the catalyst slurry in the reaction chamber lining 2 to the quartz container 18 at a rate of 500 mL / min. Since the amount of the metal precursor solution prepared each time is just enough for one catalyst preparation, in step (2), all the metal precursor solution in the quartz container 18 is transported to the reaction chamber lining 2, and there is no metal precursor solution in the quartz container 18. At this time, the catalyst slurry can be transported to the quartz container 18 again.

[0042] (4) The catalyst slurry is then separated into solid and liquid by centrifugation or vacuum filtration, and the catalyst solid particles obtained after the solid-liquid separation are vacuum dried at 60° C. After the catalyst solid particles are completely dried, the catalyst solid particles are ground for 30 minutes, and then the catalyst solid is heat treated at 200° C. for 300 minutes to obtain a fuel cell catalyst in which platinum nanoparticles are embedded in the pores of the carbon carrier.

[0043] The catalyst prepared in this example is denoted as Pt / C.

[0044] Example 2

[0045] This example uses the preparation device of the present invention to prepare a fuel cell catalyst through the following steps:

[0046] (1) The flange 21 of the pressure chamber 1 is opened, 1500 mg of porous carbon powder is added to the reaction chamber lining 2, and then the flange 21 is used to seal the pressure chamber 1, the molecular pump unit 11 is turned on, and the second valve 12 is opened. At this time, the first valve 10, the third valve 17, the pressure relief valve 19, the peristaltic pump 16, the ultrasonic generator 13, the transducer 14, etc. are all in the closed state, and the pressure chamber 1 is pumped into 10 by the molecular pump unit 11. -6 Pa negative pressure vacuum environment, the porous carbon powder is in a negative pressure vacuum environment, then the heating temperature is set to 75°C through the temperature control system 7, the temperature control system 7 controls the voltage of the heating power supply 6, so that the heating element 4 reaches a heating temperature of 75°C, the porous carbon powder is heated in the negative pressure vacuum environment, after heating for 300 minutes, the heating element 4 is controlled by the temperature control system 7 to stop heating, the porous carbon powder is cooled to 60°C in the reaction chamber lining 2, and the carbon carrier is obtained. During the heating process, the temperature measuring element 5 measures the temperature in real time and transmits the signal to the temperature control system 7, and the temperature control system 7 adjusts the heating temperature of the heating element 4 according to the temperature measured by the temperature measuring element 5 to keep the temperature relatively constant.

[0047] (2) The molecular pump unit 11 and the second valve 12 are closed, the third valve 17 is opened, and the peristaltic pump 16 is turned on. The metal precursor solution prepared in advance and added to the quartz container 18 is transported to the reaction chamber lining 2 at a rate of 2 mL / min by controlling the peristaltic pump 16. A total of 833 mL of the metal precursor solution is transported. The metal precursor solution of this embodiment is prepared by dissolving 3335.93 mg of platinum acetylacetonate (platinum salt precursor) and 1015.36 g of cobalt acetylacetonate (transition metal precursor) in 833 mL of N,N-dimethylformamide solution (organic solvent). It is a platinum alloy precursor solution with a platinum metal ion concentration of 2 g / L and a metal ion concentration of 0.2 g / L. After the metal precursor solution is added, the peristaltic pump 16 and the third valve 17 are turned on, and the ultrasonic generator 13, the transducer 14, and the amplitude transformer 15 are turned on. The ultrasonic frequency is set to 100 kHz. After 40 minutes of ultrasonic dispersion treatment, the ultrasonic generator 13, the transducer 14, and the amplitude transformer 15 are turned off, and the stirring paddle 3 is controlled to be turned on through the stirring control system 8. The stirring rate of the stirring paddle 3 is set to 200 r / min. After 40 minutes of stirring treatment, the stirring paddle 3 is controlled to stop stirring through the stirring control system 8. Open the inert gas booster 9 and the first valve 10, fill the pressure-resistant chamber 1 with inert gas through the inert gas booster 9, and make the pressure in the pressure-resistant chamber 1 reach 5MPa, close the inert gas booster 9 and the first valve 10, turn on the ultrasonic generator 13, the transducer 14, and the horn 15, set the ultrasonic frequency to 100kHz, and after 40 minutes of ultrasonic dispersion treatment, turn off the ultrasonic generator 13, the transducer 14, and the horn 15, control the stirring paddle 3 to start again through the stirring control system 8, set the stirring rate of the stirring paddle 3 to 200r / min, and control the stirring paddle 3 to stop stirring through the stirring control system 8 after 40 minutes of stirring treatment.

[0048] (3) The heating element 4 is controlled to be turned on by the temperature control system 7, and the heating temperature is set to 150°C. At the same time, the stirring control system 8 controls the stirring paddle 3 to stir at a rate of 100 r / min. After stirring and heating for 300 minutes, the catalyst slurry is obtained, the heating element 4 and the stirring paddle 3 are turned off, the pressure relief valve 19 is opened to balance the pressure in the pressure-resistant chamber 1 with the atmospheric pressure, the peristaltic pump 16 and the third valve 17 are opened, and the peristaltic pump 16 is controlled to transport the catalyst slurry in the reaction chamber lining 2 to the quartz container 18 at a rate of 500 mL / min. Since the amount of the metal precursor solution prepared each time is just enough for one catalyst preparation, in step (2), all the metal precursor solution in the quartz container 18 is transported to the reaction chamber lining 2, and there is no metal precursor solution in the quartz container 18. At this time, the catalyst slurry can be transported to the quartz container 18 again.

[0049] (4) The catalyst slurry is then separated into solid and liquid by centrifugation or vacuum filtration, and the catalyst solid particles obtained after the solid-liquid separation are vacuum dried at 100° C. After the catalyst solid particles are completely dried, the catalyst solid particles are ground for 60 minutes, and then the catalyst solid is heat treated at 150° C. for 720 minutes to obtain a fuel cell catalyst in which platinum nanoparticles are embedded in the pores of the carbon carrier.

[0050] The catalyst prepared in this example is denoted as Pt3Co / C.

[0051] Example 3

[0052] This example uses the preparation device of the present invention to prepare a fuel cell catalyst through the following steps:

[0053] (1) The flange 21 of the pressure-resistant chamber 1 is opened, and 1500 mg of porous carbon powder is added into the reaction chamber lining 2. The pressure-resistant chamber 1 is then sealed with the flange 21. The molecular pump unit 11 is turned on, and the second valve 12 is opened. At this time, the first valve 10, the third valve 17, the pressure relief valve 19, the peristaltic pump 16, the ultrasonic generator 13, the transducer 14, etc. are all in a closed state. The pressure-resistant chamber 1 is evacuated into a negative pressure vacuum environment of 1000 Pa by the molecular pump unit 11, and the porous carbon powder is in a negative pressure vacuum environment. Subsequently, the heating temperature is set to 350° C. by the temperature control system 7. The temperature control system 7 controls the voltage of the heating power supply 6 so that the heating element 4 reaches a heating temperature of 350° C. The porous carbon powder is heated in the negative pressure vacuum environment. After heating for 200 minutes, the heating element 4 is controlled by the temperature control system 7 to stop heating. The porous carbon powder is cooled to 40° C. in the reaction chamber lining 2 to obtain a carbon carrier. During the heating process, the temperature measuring element 5 measures the temperature in real time and transmits the signal to the temperature control system 7. The temperature control system 7 adjusts the heating temperature of the heating element 4 according to the temperature measured by the temperature measuring element 5 to keep the temperature in a relatively constant state.

[0054] (2) The molecular pump unit 11 and the second valve 12 are closed, the third valve 17 is opened, and the peristaltic pump 16 is turned on. The metal precursor solution prepared in advance and added to the quartz container 18 is transported to the reaction chamber lining 2 at a rate of 100 mL / min by controlling the peristaltic pump 16. A total of 4000 mL of the metal precursor solution is transported. The metal precursor solution of this embodiment is prepared by dissolving 4203.45 mg of platinum acetylacetonate (platinum salt precursor) and 3804.93 mg of iron acetylacetonate (transition metal precursor) in 4000 mL of N,N-dimethylformamide solution (organic solvent). It is a platinum alloy precursor solution with a platinum metal ion concentration of 0.53 g / L and a metal ion concentration of 0.15 g / L. After the metal precursor solution is added, the peristaltic pump 16 and the third valve 17 are turned off, and the ultrasonic generator 13, the transducer 14, and the amplitude transformer 15 are turned on. The ultrasonic frequency is set to 50kHz. After 30 minutes of ultrasonic dispersion treatment, the ultrasonic generator 13, the transducer 14, and the amplitude transformer 15 are turned off, and the stirring paddle 3 is controlled by the stirring control system 8. The stirring rate of the stirring paddle 3 is set to 400r / min. After 30 minutes of stirring treatment, the stirring paddle 3 is controlled by the stirring control system 8 to stop stirring. Open the inert gas booster 9 and the first valve 10, fill the pressure-resistant chamber 1 with inert gas through the inert gas booster 9, and make the pressure in the pressure-resistant chamber 1 reach 2MPa, close the inert gas booster 9 and the first valve 10, turn on the ultrasonic generator 13, the transducer 14, and the horn 15, set the ultrasonic frequency to 50kHz, and after 30 minutes of ultrasonic dispersion treatment, turn off the ultrasonic generator 13, the transducer 14, and the horn 15, control the stirring paddle 3 to start again through the stirring control system 8, set the stirring rate of the stirring paddle 3 to 400r / min, and control the stirring paddle 3 to stop stirring through the stirring control system 8 after 30 minutes of stirring treatment.

[0055] (3) The heating element 4 is controlled to be turned on by the temperature control system 7, and the heating temperature is set to 250°C. At the same time, the stirring control system 8 controls the stirring paddle 3 to stir at a rate of 50r / min. After stirring and heating for 2000min, the catalyst slurry is obtained, the heating element 4 and the stirring paddle 3 are turned off, the pressure relief valve 19 is opened to balance the pressure in the pressure-resistant chamber 1 with the atmospheric pressure, the peristaltic pump 16 and the third valve 17 are opened, and the peristaltic pump 16 is controlled to transport the catalyst slurry in the reaction chamber lining 2 to the quartz container 18 at a rate of 500mL / min. Since the amount of the metal precursor solution prepared each time is just enough for one catalyst preparation, in step (2), all the metal precursor solution in the quartz container 18 is transported to the reaction chamber lining 2, and there is no metal precursor solution in the quartz container 18. At this time, the catalyst slurry can be transported to the quartz container 18 again.

[0056] (4) The catalyst slurry is then separated into solid and liquid by centrifugation or vacuum filtration, and the catalyst solid particles obtained after the solid-liquid separation are vacuum dried at 80° C. After the catalyst solid particles are completely dried, the catalyst solid particles are ground for 50 minutes, and then the catalyst solid is heat-treated at 230° C. for 120 minutes to obtain a fuel cell catalyst in which platinum nanoparticles are embedded in the pores of the carbon carrier.

[0057] The catalyst prepared in this example is denoted as PtFe / C.

[0058] Example 4

[0059] This embodiment adopts the same method as that of Embodiment 1 to prepare the fuel cell catalyst, except that: the metal precursor solution in this embodiment is prepared by dissolving 4290.98 mg of platinum acetylacetonate (platinum salt precursor) and 2825.5 mg of nickel acetylacetonate (transition metal precursor) in 1072 mL of N,N-dimethylformamide solution (organic solvent), which is a platinum alloy precursor solution with a platinum metal ion concentration of 2 g / L and a metal ion concentration of 0.6 g / L.

[0060] The catalyst prepared in this example is denoted as PtNi / C.

[0061] Comparative Example 1

[0062] This comparative example adopts the same method as Example 1 to prepare the same catalyst, except that: in this comparative example, the porous carbon powder is not heated under negative pressure conditions, and no inert gas is introduced during the ultrasonic dispersion treatment. Instead, the metal precursor solution is directly added to the porous carbon powder for ultrasonic dispersion and stirring.

[0063] Comparative Example 2

[0064] This comparative example adopts the same method as Example 2 to prepare the same catalyst, except that: in this comparative example, the porous carbon powder is not heated under negative pressure conditions, and no inert gas is introduced during the ultrasonic dispersion treatment. Instead, the metal precursor solution is directly added to the porous carbon powder for ultrasonic dispersion and stirring.

[0065] Comparative Example 3

[0066] This comparative example adopts the same method as Example 3 to prepare the same catalyst, except that: in this comparative example, the porous carbon powder is not heated under negative pressure conditions, and no inert gas is introduced during the ultrasonic dispersion treatment. Instead, the metal precursor solution is directly added to the porous carbon powder for ultrasonic dispersion and stirring.

[0067] Comparative Example 4

[0068] This comparative example adopts the same method as Example 4 to prepare the same catalyst, except that: in this comparative example, the porous carbon powder is not heated under negative pressure conditions, and no inert gas is introduced during the ultrasonic dispersion treatment. Instead, the metal precursor solution is directly added to the porous carbon powder for ultrasonic dispersion and stirring.

[0069] The initial activity of the fuel cell catalysts prepared in the examples and comparative examples in a 0.1M HClO4 solution saturated with N2 and the activity after 30,000 cycles at a potential of 0.6 to 0.95 V were measured. The results are shown in Table 1.

[0070] Table 1

[0071]

[0072] It can be seen from Table 1 that the activity decay rate of the fuel cell catalyst prepared by the present invention is at a lower level than that of the comparative example. Figure 5 It can be shown that the fuel cell catalyst prepared by the present invention has a low activity decay rate and a high mass activity retention rate, which fully demonstrates that the fuel cell catalyst prepared by the present invention has excellent durability. The reason why the activity decay rate of Example 1 in the table reaches 25.66% is that the nanoparticles in Example 1 are Pt nanoparticles, not alloy nanoparticles, and the performance of Pt nanoparticles themselves is weaker than that of alloy nanoparticles.

[0073] pass Figure 2 , 3 By comparison, it can be seen that in the fuel cell catalyst prepared by the present invention, the nanoparticles are evenly distributed in the pores of the carbon carrier without obvious agglomeration, and the average particle size is about 5nm. In the fuel cell catalyst prepared in Comparative Example 2, the nanoparticles are spherical, and it can be clearly observed that the nanoparticles in Comparative Example 2 are dispersed on the surface of the carbon carrier. At the same time, the focal length of the TEM must be adjusted from underfocus to overfocus to observe the nanoparticles in Example 2, indicating that the surface of the nanoparticles in Example 2 is covered with a very thin carbon layer, which further illustrates that in the fuel cell catalyst prepared by the present invention, the nanoparticles are successfully embedded in the pores of the carbon carrier.

[0074] pass Figure 4It can be seen that the XRD diffraction peak positions of the PtNi / C catalyst are approximately at 41.27°, 48.04°, 70.29° and 84.9°, and the positions of these diffraction peaks correspond to the diffraction peak positions of the (111), (200), (220) and (311) crystal planes of the face-centered cubic (fcc) structure of the Pt metal (JCPDS 65-9445). Compared with the diffraction peak position of pure Pt in the catalyst in Example 1 (JCPDS 04-0802), an obvious positive shift occurs. This is because the atomic radius of Ni is smaller than that of Pt, and the lattice spacing is contracted due to Ni entering the Pt lattice, which proves that the preparation method of the present invention will not have a negative impact on the formation of the Pt alloy, and the transition metal can normally enter the Pt lattice to form a platinum alloy.

[0075] In summary, the fuel cell catalyst prepared by the preparation method of the present invention can allow the metal ions to fully penetrate into the pores of the carbon carrier, and perform in-situ reduction growth to synthesize metal nanoparticles, so that the nanoparticles are embedded in the pores of the carbon carrier, effectively enhancing the interaction between the carbon carrier and the metal nanoparticles. At the same time, the constraint effect of the carbon carrier pores on the metal nanoparticles is utilized to reduce the probability of migration, shedding, and agglomeration of the nanoparticles during long-term electrochemical reactions, thereby ultimately improving the electrocatalytic activity and durability of the fuel cell catalyst.

[0076] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for preparing a carbon pore-anchored nanoparticle fuel cell catalyst, characterized in that: The preparation method comprises the following steps: (1) heating the porous carbon powder under negative pressure, and cooling after heating to obtain a carbon carrier; (2) adding a metal precursor solution to the carbon support obtained in step (1), subjecting the mixture to ultrasonic and stirring treatments in sequence under negative pressure conditions, then introducing an inert gas to form a positive pressure environment, and subjecting the mixture to ultrasonic and stirring treatments in sequence again until the mixture is uniformly dispersed; (3) maintaining a positive pressure environment formed by an inert gas, heating the uniformly dispersed mixed substance obtained in step (2), and stirring the mixed substance, so that the mixed substance reacts under the positive pressure condition formed by the inert gas, and after the reaction is completed, obtaining a catalyst slurry; (4) performing solid-liquid separation on the catalyst slurry obtained in step (3) to obtain catalyst particles, washing the catalyst particles with deionized water, vacuum drying the catalyst particles after washing, grinding the catalyst particles, and then vacuum heat treating the ground catalyst particles to obtain a carbon-supported nanoparticle fuel cell catalyst.

2. The preparation method according to claim 1, characterized in that: The nanoparticles include platinum and platinum alloy nanoparticles.

3. The preparation method according to claim 1, characterized in that: In the step (1), the negative pressure is 1000-10 -6 Pa, the heating temperature is 75-350°C, and the temperature is kept for 60-300 minutes. After heating, it is cooled to 20-60°C to obtain a carbon carrier.

4. The preparation method according to claim 1, characterized in that: In the step (2), the metal precursor solution is added at a rate of 2 to 100 mL / min, an inert gas is introduced to form a positive pressure environment with a pressure of 0.3 to 5 MPa, the ultrasonic frequency is 20 to 100 kHz, the ultrasonic time is 2 to 40 min, the stirring rate is 200 to 400 r / min, and the stirring time is 2 to 40 min.

5. The preparation method according to claim 1, characterized in that: In the step (3), the heating temperature is 150-250° C., the insulation time is 300-2880 min, and the stirring speed is 5-100 r / min.

6. The preparation method according to claim 1, characterized in that: In the step (4), the vacuum drying temperature is 60 to 100° C., and the grinding time is 30 to 60 minutes.

7. The preparation method according to claim 1, characterized in that: In the step (4), the vacuum heat treatment temperature is 150 to 230° C., and the vacuum heat treatment time is 120 to 720 minutes.

8. The preparation method according to claim 1, characterized in that: The porous carbon powder includes one of Ketjen Black EC-300J, Ketjen Black EC-600JD, acetylene carbon black, and Cabot BP2000.

9. The preparation method according to claim 1, characterized in that: The metal precursor solution is a platinum metal precursor solution or a platinum alloy precursor solution. The platinum metal precursor solution is prepared from a platinum salt precursor and an organic solvent, and the platinum alloy precursor solution is prepared from a platinum salt precursor, a transition metal precursor, and an organic solvent. In the platinum metal precursor solution, the platinum ion concentration is 0.5 to 2 g / L, and in the platinum alloy precursor solution, the metal ion concentration is 0.1 to 0.6 g / L.

10. A preparation device for the preparation method according to any one of claims 1 to 9, characterized in that: The preparation device comprises a pressure-resistant chamber (1), a reaction chamber lining (2), a stirring paddle (3), a heating element (4), a temperature measuring element (5), a heating power supply (6), a temperature control system (7), a stirring control system (8), an inert gas booster (9), a first valve (10), a molecular pump unit (11), a second valve (12), an ultrasonic generator (13), a transducer (14), a horn (15), a peristaltic pump (16), a third valve (17), a quartz container (18), a pressure relief valve (19), a ceramic The invention relates to a ceramic insulated electrode (20) and a flange (21), wherein the reaction chamber lining (2) is placed inside a pressure-resistant chamber (1), the pressure-resistant chamber (1) is sealed by the flange (21), the stirring paddle (3) is rotatably mounted on the top of the pressure-resistant chamber (1) and the stirring paddle (3) extends into the reaction chamber lining (2), the stirring paddle (3) is driven by a motor, the heating element (4) is mounted on the bottom of the pressure-resistant chamber (1), the reaction chamber lining (2) is placed on the heating element (4), and the temperature measuring element (5) is clamped between the reaction chamber lining (2) and the pressure-resistant chamber (1) The inert gas booster (9) is connected to the pressure-resistant cavity (1) through a pipeline between the chamber lining (2) and the heating element (4), and a first valve (10) is installed on the pipeline connecting the inert gas booster (9) and the pressure-resistant cavity (1). The molecular pump unit (11) is connected to the pressure-resistant cavity (1) through a pipeline, and a second valve (12) is installed on the pipeline connecting the molecular pump unit (11) and the pressure-resistant cavity (1). The ultrasonic generator (13) is located outside the pressure-resistant cavity (1), and the transducer (14) is installed Installed in a pressure-resistant chamber (1), the horn (15) is installed on the transducer (14) and the horn (15) extends into the reaction chamber lining (2), the quartz container (18) is connected to the reaction chamber lining (2) through a pipeline, a peristaltic pump (16) and a third valve (17) are installed on the pipeline connecting the quartz container (18) and the reaction chamber lining (2), a pressure relief valve (19) is installed on the side wall of the pressure-resistant chamber (1), and the ceramic insulating electrode (20) is embedded in the bottom flange (21) of the pressure-resistant chamber (1); The stirring control system (8) is electrically connected to the motor, the ultrasonic generator (13) is electrically connected to the transducer (14) via the ceramic insulating electrode (20), the heating element (4) is electrically connected to the heating power source (6) via the ceramic insulating electrode (20), the temperature measuring element (5) is electrically connected to the temperature control system (7) via the ceramic insulating electrode (20), and the temperature control system (7) is electrically connected to the heating power source (6).

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