Zinc-doped sub-nanoscale platinum-based catalyst as well as preparation method and application thereof

Abstract

The invention discloses a zinc-doped sub-nano platinum-based catalyst as well as a preparation method and application thereof, and belongs to the technical field of proton exchange membrane fuel cells. The preparation method comprises the following steps: adding a platinum precursor, a transition metal element precursor, a zinc precursor, a small-molecule reducing agent and a catalyst carrier into a container filled with a mixed solvent of benzyl alcohol and ethylene glycol; carrying out uniform ultrasonic treatment on the mixture in an ultrasonic instrument, and then carrying out heating reaction; washing and centrifuging, treating with an acid solution, washing and centrifuging again, and finally drying to obtain the catalyst. The catalyst is uniform in size and uniform in dispersion; the process is simple and efficient; various platinum-based catalysts can be synthesized by changing the molar ratio of platinum to transition metal and the doping amount of zinc; the catalyst shows excellent catalytic performance on a rotating disc electrode and a fuel cell membrane electrode. Zinc elements are doped into platinum metal gaps, the size of nano-particles is reduced through lattice expansion, the Pt electronic structure is optimized, and adsorption of intermediates in the ORR process is weakened.

Description

Technical Field

[0001] The present invention relates to the technical field of proton exchange membrane fuel cells, and in particular to a zinc-doped subnanometer platinum-based catalyst and a preparation method thereof, as well as applications in cathode oxygen reduction reactions of fuel cells and membrane electrodes of proton exchange membrane fuel cell devices. Background Art

[0002] Fuel cells, as efficient and clean energy conversion technologies, have become a key solution to addressing energy crises and environmental pollution due to their direct conversion of chemical energy into electricity with zero emissions. Proton exchange membrane fuel cells (PEMFCs) are considered one of the most promising energy conversion systems for electric vehicles and many electronic devices due to their high efficiency and sustainable nature. However, the kinetics of the oxygen reduction reaction (ORR) at the PEMFC cathode severely restrict their development and commercial application. Platinum (Pt), as the most promising fuel cell catalyst, exhibits promising ORR performance using a rotating disk electrode (RDE), particularly Pt-based alloys such as PtNi and PtCo. Research on surface effects (morphology, composition, size, etc.) related to ORR performance is flourishing. In recent years, increasing research has delved into the contribution of crystal structure (strain, rearrangement, defects, etc.) to enhancing ORR performance, particularly within the harsh operating environment of fuel cell membrane electrode assemblies (MEAs). However, crystal structure regulation technology still faces significant challenges, such as the uncontrollable lattice distortion and defect distribution, which lead to structural reconstruction or active phase segregation of some optimized materials under actual working conditions. Their long-term stability and catalytic efficiency are still difficult to meet the needs of industrial applications. Summary of the Invention

[0003] The purpose of the present invention is to solve the above-mentioned problems in the prior art and provide a zinc-doped subnanoscale platinum-based catalyst and its preparation method for proton exchange membrane fuel cells. The catalyst prepared by this preparation method has uniform size, higher activity, and has the potential for large-scale preparation.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for preparing a zinc-doped sub-nanoscale platinum-based catalyst comprises the following steps: adding a platinum precursor, a transition metal element precursor, a zinc precursor, a small molecule reducing agent, and a catalyst carrier into a container containing a reaction solvent, uniformly dispersing the mixture by ultrasonication, and then heating the mixture for reaction. The reaction product is washed, centrifuged, acid-washed, washed again, centrifuged, and finally dried to obtain the zinc-doped sub-nanoscale platinum-based catalyst.

[0006] The platinum precursor is at least one of platinum acetylacetonate and chloroplatinic acid hexahydrate, the transition metal element precursor is at least one of basic cobalt carbonate and basic nickel carbonate, the zinc precursor is zinc acetylacetonate, and the small molecule reducing agent is at least one of ascorbic acid and glucose; the reaction solvent is at least one of benzyl alcohol and ethylene glycol.

[0007] The molar ratio of the platinum precursor to the transition metal precursor is 1-3:1; the molar ratio of the platinum precursor to the zinc precursor is 1-6:1.

[0008] The catalyst carrier is at least one of Ketjenblack-300 and Ketjenblack-600 carbon powders.

[0009] The heating reaction temperature is 160-200° C., and the reaction time is 5-10 h.

[0010] The washing is performed using a mixed solution of ethanol and water; and the pickling is performed using a nitric acid solution with a concentration of 0.5-2 mol / L.

[0011] A zinc-doped subnanometer platinum-based catalyst is prepared by the above preparation method; the mass fraction of the platinum element is 10% to 60%, and the average particle size of the catalyst is 1 to 4 nm.

[0012] The zinc-doped sub-nanoscale platinum-based catalyst prepared by the present invention is doped with zinc into the gaps between platinum metals, which reduces the size of nanoparticles and optimizes the electronic structure of Pt through lattice expansion, thereby reducing the ORR process. Adsorption of intermediates.

[0013] The zinc-doped sub-nanoscale platinum-based catalyst is used in the cathode oxygen reduction reaction of a fuel cell and in the membrane electrode of a proton exchange membrane fuel cell device.

[0014] Essentially, metal lattice distortion leads to different behaviors in charge transfer between the host and the guest, resulting in an effective catalytic electronic structure. Nanoparticles are an ideal catalyst model for achieving high lattice distortion due to their inherent high specific surface area and high surface atomic ratio. In traditional Pt-based nanoparticles, heteroatoms are usually alloyed with Pt in a substitutional manner to optimize its electronic structure, which falls into the category of lattice contraction; while the present invention dopes zinc into the gaps between platinum metals, and achieves a reduction in nanoparticle size and an optimization of Pt electronic structure through lattice expansion, thereby reducing the ORR process. The adsorption of intermediates can enhance the ORR performance of Pt-based catalysts.

[0015] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0016] 1. This method utilizes elemental zinc doping to prepare the catalyst, and the catalyst prepared has higher activity and the catalyst size reaches the sub-nanometer level.

[0017] 2. This method adopts a liquid phase preparation method with a yield of more than 98%, and the single preparation amount can reach 10 grams, which has the potential for mass production.

[0018] 3. This method adopts a liquid phase preparation method, with minimal loss of precious metals and a simple and efficient synthesis process.

[0019] 4. This method is universal and can prepare platinum-based alloy catalysts with different components by using different transition metal precursors.

[0020] 5. The preparation process of this method can achieve stable catalyst output, and the prepared platinum-based catalyst has excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a transmission electron micrograph of the platinum-based catalyst in Example 1;

[0022] Figure 2 Statistical diagram of particle size of the platinum-based catalyst in Example 1;

[0023] Figure 3 1 is the XRD pattern of the platinum-based catalysts in Example 1 and Comparative Example 1, wherein Zn-PtCo / C is the platinum-based catalyst prepared in Example 1, and PtCo / C is the platinum-based catalyst prepared in Comparative Example 1;

[0024] Figure 4 1 is the XPS spectrum of the platinum-based catalysts in Example 1 and Comparative Example 1, wherein Zn-PtCo / C is the platinum-based catalyst prepared in Example 1, and PtCo / C is the platinum-based catalyst prepared in Comparative Example 1;

[0025] Figure 5 is the d-band center of the platinum-based catalysts in Example 1 and Comparative Example 1, wherein Zn-PtCo / C is the platinum-based catalyst prepared in Example 1, and PtCo / C is the platinum-based catalyst prepared in Comparative Example 1;

[0026] Figure 6 is the cyclic voltammetry curve of the platinum-based catalyst in Example 1 ( Figure 6 a) and linear sweep voltammetry curves ( Figure 6 (b)

[0027] Figure 7 This is a hydrogen-oxygen polarization curve of a fuel cell membrane electrode prepared using the platinum-based catalyst of Example 1;

[0028] Figure 8 This is a hydrogen-air polarization curve of a fuel cell membrane electrode prepared using the platinum-based catalyst of Example 1;

[0029] Figure 9 This is a photo of the sample quality prepared using the platinum-based catalyst in Example 10. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] This invention achieves structural design for the platinum-based metal alloy catalyst by introducing zinc. The zinc atoms insert into the interstices of the platinum nanocrystals, causing lattice expansion and thus enhancing their intrinsic activity. Furthermore, the introduction of zinc atoms limits the growth and agglomeration of the nanocrystals, forming uniform sub-nanometer particles on the carbon powder. Furthermore, the liquid-phase method retains more precious metals, significantly reducing precious metal loss. The yield reaches over 98%, making it suitable for large-scale production.

[0032] In some embodiments of the present invention, a method for preparing a zinc-doped sub-nanoscale platinum-based catalyst comprises the following steps:

[0033] S1, adding a platinum precursor, a transition metal element precursor, a zinc precursor, a small molecule reducing agent, and a catalyst support into a container containing a reaction solvent;

[0034] S2, ultrasonically homogenizing the above mixture in an ultrasonic instrument;

[0035] S3, using a certain temperature to carry out heating reaction;

[0036] S4, washing with the mixed solution and centrifuging;

[0037] S5. Washing with an acid solution, washing again, centrifuging, and finally drying to obtain the final catalyst.

[0038] In some embodiments of the present invention, in S1, the platinum precursor is at least one of platinum acetylacetonate and chloroplatinic acid hexahydrate, the transition metal element precursor is at least one of basic cobalt carbonate and basic nickel carbonate, the zinc precursor is zinc acetylacetonate, and the small molecule reducing agent is at least one of ascorbic acid and glucose.

[0039] In some embodiments of the present invention, in S1, the molar ratio of the platinum precursor to the transition metal precursor may be 1-3:1, and the molar ratio of the platinum precursor to the zinc precursor may be 1-6:1.

[0040] In some embodiments of the present invention, the catalyst support may be Ketjenblack-300 or Ketjenblack-600 carbon powder.

[0041] In some embodiments of the present invention, in S1, the reaction solvent may be at least one of benzyl alcohol and ethylene glycol.

[0042] In some embodiments of the present invention, in S2, the ultrasonication time may be 30 to 60 minutes.

[0043] Mixing under the above conditions is conducive to uniform mixing of the raw materials and obtaining a platinum-based catalyst with uniform composition.

[0044] In some embodiments of the present invention, in S3, the heating reaction temperature may be 160-200° C., and the reaction time may be 5-10 h.

[0045] Carrying out the reaction under the above conditions can produce a platinum-based catalyst with a complete structure and fine and uniformly distributed active particles.

[0046] In some embodiments of the present invention, in S4 and S5, the washing and centrifuging steps may use a mixed solution of ethanol / water in a volume ratio of 1 to 3:1, and the number of washing times may be 2 to 5 times.

[0047] In some embodiments of the present invention, in S5, the acid solution is a nitric acid solution with a concentration of 0.5-2 mol / L; by controlling the pickling conditions, the incompletely alloyed metal can be removed and the catalyst surface can be cleaned.

[0048] In some embodiments of the present invention, in S5, the drying temperature may be 40-80° C., and the drying time may be 2-12 h.

[0049] In a typical embodiment of the present invention, there is also provided a use of the platinum-based catalyst in the above embodiment of the present invention or the platinum-based catalyst prepared by the preparation method in the above embodiment in preparing a fuel cell membrane electrode.

[0050] In one embodiment of the present invention, a method for preparing a membrane electrode is provided, comprising: adding a platinum-based catalyst to a mixed solution of water and an alcohol solvent, mixing well, and then adding a Nafion solution to obtain a catalyst ink; spraying the catalyst ink onto a proton exchange membrane, and then assembling it with a gas diffusion layer to obtain a fuel cell membrane electrode.

[0051] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0052] Example 1

[0053] The present invention provides a method for preparing a zinc-doped sub-nanoscale platinum-based catalyst, comprising the following steps:

[0054] S1. Weigh 200 mg of platinum acetylacetonate, 30 mg of basic cobalt carbonate, 45 mg of zinc acetylacetonate, 540 mg of ascorbic acid, and 230 mg of Ketjenblack-300 carbon powder into a beaker, and add 10 mL of benzyl alcohol and 10 mL of ethylene glycol.

[0055] S2. Place the container containing the above mixture in an ultrasonic instrument and sonicate for 30 minutes until it is evenly dispersed;

[0056] S3, placing the homogeneous mixture on an oil bath heating device, turning on the speed of 600 rpm and the temperature of 200 ° C, and carrying out the reaction process for 5 hours;

[0057] S4, washing the mixture of the above reaction with a mixed solution of ethanol and water for 3 times by centrifugation;

[0058] S5. Place the above crude product in a beaker, add 1 mol / L nitric acid solution, raise the temperature to 70°C, keep warm for 2 hours, and finally wash and centrifuge it three times with a mixed solution of ethanol and water, and dry it in an oven at 50°C for 6 hours to obtain the final product catalyst.

[0059] Example 2

[0060] The present invention provides a method for preparing a zinc-doped sub-nanoscale platinum-based catalyst, comprising the following steps:

[0061] S1. Weigh 200 mg of platinum acetylacetonate, 30 mg of basic cobalt carbonate, 45 mg of zinc acetylacetonate, 540 mg of ascorbic acid, and 140 mg of Ketjenblack-300 carbon powder into a beaker, and add 10 mL of benzyl alcohol and 10 mL of ethylene glycol.

[0062] S2. Place the container containing the above mixture in an ultrasonic instrument and sonicate for 30 minutes until uniformly dispersed;

[0063] S3, placing the homogeneous mixture on an oil bath heating device, turning on the speed of 600 rpm and the temperature of 200 ° C, and carrying out the reaction process for 5 hours;

[0064] S4, washing the mixture of the above reaction with a mixed solution of ethanol and water for 3 times by centrifugation;

[0065] S5. Place the above crude product in a beaker, add 1 mol / L nitric acid solution, raise the temperature to 70°C, keep warm for 2 hours, and finally wash and centrifuge it three times with a mixed solution of ethanol and water, and dry it in an oven at 50°C for 6 hours to obtain the final product catalyst.

[0066] Example 3

[0067] The present invention provides a method for preparing a zinc-doped sub-nanoscale platinum-based catalyst, comprising the following steps:

[0068] S1. Weigh 200 mg of platinum acetylacetonate, 30 mg of basic cobalt carbonate, 45 mg of zinc acetylacetonate, 540 mg of ascorbic acid, and 65 mg of Ketjenblack-300 carbon powder into a beaker, and add 10 mL of benzyl alcohol and 10 mL of ethylene glycol.

[0069] S2. Place the container containing the above mixture in an ultrasonic instrument and sonicate for 30 minutes until uniformly dispersed;

[0070] S3, placing the homogeneous mixture on an oil bath heating device, turning on the speed of 600 rpm and the temperature of 200 ° C, and carrying out the reaction process for 5 hours;

[0071] S4, washing the mixture of the above reaction with a mixed solution of ethanol and water for 3 times by centrifugation;

[0072] S5. Place the above crude product in a beaker, add 1 mol / L nitric acid solution, raise the temperature to 70°C, keep warm for 2 hours, and finally wash and centrifuge it three times with a mixed solution of ethanol and water, and dry it in an oven at 50°C for 6 hours to obtain the final product catalyst.

[0073] Example 4

[0074] The present invention provides a method for preparing a zinc-doped sub-nanoscale platinum-based catalyst, comprising the following steps:

[0075] S1. Weigh 200 mg of platinum acetylacetonate, 30 mg of basic cobalt carbonate, 15 mg of zinc acetylacetonate, 540 mg of ascorbic acid, and 230 mg of Ketjenblack-300 carbon powder into a beaker, and add 10 mL of benzyl alcohol and 10 mL of ethylene glycol.

[0076] S2. Place the container containing the above mixture in an ultrasonic instrument and sonicate for 30 minutes until uniformly dispersed;

[0077] S3, placing the homogeneous mixture on an oil bath heating device, turning on the speed of 600 rpm and the temperature of 200 ° C, and carrying out the reaction process for 5 hours;

[0078] S4, washing the mixture of the above reaction with a mixed solution of ethanol and water for 3 times by centrifugation;

[0079] S5. Place the above crude product in a beaker, add 1 mol / L nitric acid solution, raise the temperature to 70°C, keep warm for 2 hours, and finally wash and centrifuge it three times with a mixed solution of ethanol and water, and dry it in an oven at 50°C for 6 hours to obtain the final product catalyst.

[0080] Example 5

[0081] The present invention provides a method for preparing a zinc-doped sub-nanoscale platinum-based catalyst, comprising the following steps:

[0082] S1. Weigh 200 mg of platinum acetylacetonate, 30 mg of basic cobalt carbonate, 60 mg of zinc acetylacetonate, 540 mg of ascorbic acid, and 230 mg of Ketjenblack-300 carbon powder into a beaker, and add 10 mL of benzyl alcohol and 10 mL of ethylene glycol.

[0083] S2. Place the container containing the above mixture in an ultrasonic instrument and sonicate for 30 minutes until uniformly dispersed;

[0084] S3, placing the homogeneous mixture on an oil bath heating device, turning on the speed of 600 rpm and the temperature of 200 ° C, and carrying out the reaction process for 5 hours;

[0085] S4, washing the mixture of the above reaction with a mixed solution of ethanol and water for 3 times by centrifugation;

[0086] S5. Place the above crude product in a beaker, add 1 mol / L nitric acid solution, raise the temperature to 70°C, keep warm for 2 hours, and finally wash and centrifuge it three times with a mixed solution of ethanol and water, and dry it in an oven at 50°C for 6 hours to obtain the final product catalyst.

[0087] Example 6

[0088] The present invention provides a method for preparing a zinc-doped sub-nanoscale platinum-based catalyst, comprising the following steps:

[0089] S1. Weigh 200 mg of platinum acetylacetonate, 30 mg of basic nickel carbonate, 45 mg of zinc acetylacetonate, 540 mg of ascorbic acid, and 230 mg of Ketjenblack-300 carbon powder into a beaker, and add 10 mL of benzyl alcohol and 10 mL of ethylene glycol.

[0090] S2. Place the container containing the above mixture in an ultrasonic instrument and sonicate for 30 minutes until uniformly dispersed;

[0091] S3, placing the homogeneous mixture on an oil bath heating device, turning on the speed of 600 rpm and the temperature of 200 ° C, and carrying out the reaction process for 5 hours;

[0092] S4, washing the mixture of the above reaction with a mixed solution of ethanol and water for 3 times by centrifugation;

[0093] S5. Place the above crude product in a beaker, add 1 mol / L nitric acid solution, raise the temperature to 70°C, keep warm for 2 hours, and finally wash and centrifuge it three times with a mixed solution of ethanol and water, and dry it in an oven at 50°C for 6 hours to obtain the final product catalyst.

[0094] Example 7

[0095] The present invention provides a method for preparing a zinc-doped sub-nanoscale platinum-based catalyst, comprising the following steps:

[0096] S1. Weigh 200 mg of platinum acetylacetonate, 15 mg of basic cobalt carbonate, 45 mg of zinc acetylacetonate, 540 mg of ascorbic acid, and 230 mg of Ketjenblack-300 carbon powder into a beaker, and add 10 mL of benzyl alcohol and 10 mL of ethylene glycol.

[0097] S2. Place the container containing the above mixture in an ultrasonic instrument and sonicate for 30 minutes until uniformly dispersed;

[0098] S3, placing the homogeneous mixture on an oil bath heating device, turning on the speed of 600 rpm and the temperature of 200 ° C, and carrying out the reaction process for 5 hours;

[0099] S4, washing the mixture of the above reaction with a mixed solution of ethanol and water for 3 times by centrifugation;

[0100] S5. Place the above crude product in a beaker, add 1 mol / L nitric acid solution, raise the temperature to 70°C, keep warm for 2 hours, and finally wash and centrifuge it three times with a mixed solution of ethanol and water, and dry it in an oven at 50°C for 6 hours to obtain the final product catalyst.

[0101] Example 8

[0102] The present invention provides a method for preparing a zinc-doped sub-nanoscale platinum-based catalyst, comprising the following steps:

[0103] S1. Weigh 200 mg of platinum acetylacetonate, 7 mg of basic cobalt carbonate, 45 mg of zinc acetylacetonate, 540 mg of ascorbic acid, and 230 mg of Ketjenblack-300 carbon powder into a beaker, and add 10 mL of benzyl alcohol and 10 mL of ethylene glycol.

[0104] S2. Place the container containing the above mixture in an ultrasonic instrument and sonicate for 30 minutes until uniformly dispersed;

[0105] S3, placing the homogeneous mixture on an oil bath heating device, turning on the speed of 600 rpm and the temperature of 200 ° C, and carrying out the reaction process for 5 hours;

[0106] S4, washing the mixture of the above reaction with a mixed solution of ethanol and water for 3 times by centrifugation;

[0107] S5. Place the above crude product in a beaker, add 1 mol / L nitric acid solution, raise the temperature to 70°C, keep warm for 2 hours, and finally wash and centrifuge it three times with a mixed solution of ethanol and water, and dry it in an oven at 50°C for 6 hours to obtain the final product catalyst.

[0108] Example 9

[0109] The present invention provides a method for preparing a zinc-doped sub-nanoscale platinum-based catalyst, comprising the following steps:

[0110] S1. Weigh 200 mg of platinum acetylacetonate, 30 mg of basic cobalt carbonate, 45 mg of zinc acetylacetonate, 540 mg of ascorbic acid, and 230 mg of Ketjenblack-600 carbon powder into a beaker, and add 10 mL of benzyl alcohol and 10 mL of ethylene glycol.

[0111] S2. Place the container containing the above mixture in an ultrasonic instrument and sonicate for 30 minutes until uniformly dispersed;

[0112] S3, placing the homogeneous mixture on an oil bath heating device, turning on the speed of 600 rpm and the temperature of 200 ° C, and carrying out the reaction process for 5 hours;

[0113] S4, washing the mixture of the above reaction with a mixed solution of ethanol and water for 3 times by centrifugation;

[0114] S5. Place the above crude product in a beaker, add 1 mol / L nitric acid solution, raise the temperature to 70°C, keep warm for 2 hours, and finally wash and centrifuge it three times with a mixed solution of ethanol and water, and dry it in an oven at 50°C for 6 hours to obtain the final product catalyst.

[0115] Example 10

[0116] The present invention provides a method for preparing a zinc-doped sub-nanoscale platinum-based catalyst, comprising the following steps:

[0117] S1. Weigh 7000 mg of platinum acetylacetonate, 1050 mg of basic cobalt carbonate, 1575 mg of zinc acetylacetonate, 18900 mg of ascorbic acid, and 7500 mg of Ketjenblack-300 carbon powder into a beaker, and add 300 mL of benzyl alcohol and 300 mL of ethylene glycol.

[0118] S2. Place the container containing the above mixture in an ultrasonic instrument and sonicate for 60 min until uniform dispersion;

[0119] S3, placing the homogeneous mixture on an oil bath heating device, turning on the speed of 600 rpm and the temperature of 200 ° C, and carrying out the reaction process for 5 hours;

[0120] S4, washing the mixture of the above reaction with a mixed solution of ethanol and water for 3 times by centrifugation;

[0121] S5. Place the above crude product in a beaker, add 1 mol / L nitric acid solution, raise the temperature to 70°C, keep warm for 2 hours, and finally wash and centrifuge it three times with a mixed solution of ethanol and water, and dry it in an oven at 50°C for 6 hours to obtain the final product catalyst.

[0122] Comparative Example 1

[0123] The preparation method of the comparative example catalyst of the present invention comprises the following steps:

[0124] S1. Weigh 200 mg of platinum acetylacetonate, 30 mg of basic cobalt carbonate, 540 mg of ascorbic acid, and 230 mg of Ketjenblack-300 carbon powder into a beaker, and add 10 mL of benzyl alcohol and 10 mL of ethylene glycol.

[0125] S2. Place the container containing the above mixture in an ultrasonic instrument and sonicate for 30 minutes until uniformly dispersed;

[0126] S3, placing the homogeneous mixture on an oil bath heating device, turning on the speed of 600 rpm and the temperature of 200 ° C, and carrying out the reaction process for 5 hours;

[0127] S4, washing the mixture of the above reaction with a mixed solution of ethanol and water for 3 times by centrifugation;

[0128] S5. Place the above crude product in a beaker, add 1 mol / L nitric acid solution, raise the temperature to 70°C, keep warm for 2 hours, and finally wash and centrifuge it three times with a mixed solution of ethanol and water, and dry it in an oven at 50°C for 6 hours to obtain the final product catalyst.

[0129] Application Examples

[0130] The catalysts prepared in Examples 1 to 10 and Comparative Example 1 were used in fuel cell membrane electrodes, and the preparation method was as follows:

[0131] 10 mg of catalyst was added to a mixture of 0.1 mL of water and 1 mL of isopropanol, and after ultrasonic homogenization, it was added to 100 μL of a Nafion solution with a Nafion mass fraction of 5% to obtain catalyst ink. The catalyst ink was then evenly sprayed onto a proton exchange membrane (Gore, ~12 μm) using a spray gun and then assembled with a gas diffusion layer (Toray, Japan, TGP-H-060) to form a fuel cell membrane electrode.

[0132] Performance Testing

[0133] 1. Platinum-based catalyst

[0134] 1) Element content: The atomic ratio and mass ratio of various element contents were analyzed using scanning electron microscope-energy dispersive spectrometer.

[0135] 2) Average particle size of active particles: Based on transmission electron microscopy images, the particle size is measured and statistically analyzed using nano-measurement software.

[0136] 3) Morphology: The morphology was observed using a transmission electron microscope.

[0137] 4) Structure: XRD pattern was tested using X-ray diffractometer.

[0138] 5) Electrochemically active area (ECSA) of the catalyst: The catalyst was coated onto a rotating disk electrode to prepare the working electrode to be used. A saturated calomel electrode was used as the reference electrode and a graphite rod was used as the counter electrode. The catalyst was first activated by cyclic voltammetry in an N2-saturated HClO4 solution with a concentration of 0.1 mol / L at a scan rate of 50 mV·s. -1 The scanning potential range was from -0.25 V to 0.96 V, and the ECSA calculation was performed using the hydrogen region of the electrochemical cyclic voltammetry curve.

[0139] 6) Mass activity: ORR performance was tested using linear sweep voltammetry in an O2-saturated HClO4 solution with a concentration of 0.1 mol / L. The scan rate and rotation speed were maintained at 10 mV·s, respectively. -1and 1600 rpm, and the current at 0.9 V (vs. RHE) was taken, and the mass activity was calculated using the KL equation.

[0140] 2. Fuel cell membrane electrode

[0141] Fuel cell performance was evaluated using a standardized testing procedure. The experimental system temperature was maintained at 80°C, and the reactant gas backpressure was maintained at 150 kPa (absolute) by a precision pressure controller. Prior to data acquisition, a multi-step voltage cycling activation procedure was performed: 8–10 cycles were performed at 0.85 V, 0.6 V, 0.5 V, and 0.4 V in constant potential mode, each for 300 seconds, until the current density change rate was less than 2% / min, indicating electrochemical steady-state.

[0142] The test system includes two gas combination modes: in the pure oxygen system, the anode / cathode hydrogen and oxygen gas flow rates are both set to 500 standard cubic centimeters per minute (sccm); in the air system, the anode hydrogen flow rate is maintained at 500 sccm, and the cathode air flow rate is increased to 1500 sccm to compensate for the difference in oxygen concentration. In both modes, the battery performance is characterized by steady-state polarization curves. Durability evaluation uses constant current mode at 1.5 A·cm -2 During continuous operation at high current density, hydrogen and oxygen were supplied to the anode and cathode at a constant flow rate of 200 sccm, respectively. Voltage decay was monitored in real time to assess catalyst durability. Tables 1 and 2 show the performance test results for the platinum-based catalyst and fuel cell membrane electrode, respectively.

[0143] Table 1

[0144]

[0145] The data in Table 1 demonstrate a significant correlation between the performance of platinum-based catalysts and their component ratios and material selection. The platinum-based catalysts prepared using the present invention not only effectively control the size of active particles, but also maintain excellent electrochemically active area and mass activity. Similarly, by replacing the transition metal component with nickel instead of cobalt, the catalytic system maintains its ideal structural state.

[0146] Table 2

[0147]

[0148] It can be seen from Table 2 that the power density of the fuel cell membrane electrode prepared using the platinum-based catalyst of the present invention is maintained at a relatively high level.

[0149] Figure 1 The TEM characterization results of the catalyst in Example 1 show that the platinum-based active component is uniformly dispersed on the surface of the two-dimensional carbon support in the form of nanoparticles with uniform particle size, and no obvious particle agglomeration is observed. Figure 2 Statistical analysis of the particle size distribution shows that the catalyst particle size is concentrated in the range of 2.1~3 nm, which meets the requirement of high-efficiency catalyst for particle size homogeneity.

[0150] Figure 3 The XRD patterns of Example 1 and Comparative Example 1 are compared, showing two aspects: on the one hand, the ratio of the full width at half maximum (FWHM) of the two is 2.46, indicating that the particle size is greatly reduced; on the other hand, the obvious shift of the diffraction peak to low angles indicates the expansion of the lattice. Figure 4 The XPS graphs of Example 1 and Comparative Example 1 are analyzed to analyze their chemical composition and electronic interaction. The Pt 4f of Zn-PtCo / C can be divided into 6 sub-peaks, corresponding to 4f 7 / 2 and 4f 5 / 2 Pt 0 , Pt 2+ and Pt 4+ Electron orbit, compared with PtCo / C, the Pt 0 shifted toward higher binding energies, which can be attributed to its enhanced electronic interactions. Figure 5 The d-band center of Example 1 and Comparative Example 1, in the Zn-PtCo / C catalyst, the d-band center moves significantly away from the Fermi level, which can effectively weaken the The adsorption energy of the intermediate can achieve rapid desorption of H2O.

[0151] Figure 6 The electrochemical performance test data showed that the catalyst mass activity of Example 1 reached 0.94 A·mg Pt -1 , its cyclic voltammetry curve (scan rate: 50 mV·s -1 ) The calculated ECSA is 74.5 m²·g -1 , indicating that the material has excellent catalytic activity and stability.

[0152] Figure 7 The hydrogen-oxygen polarization curve of the fuel cell membrane electrode prepared using the platinum-based catalyst in Example 1 is shown in the figure. As can be seen from the figure, the hydrogen-oxygen peak power density of the fuel cell membrane electrode reaches 2.7 W / cm 2 ; Figure 8 The hydrogen-air polarization curve of the fuel cell membrane electrode prepared using the platinum-based catalyst in Example 1 is shown in the figure. As can be seen from the figure, the hydrogen-air peak power density of the fuel cell membrane electrode reaches 1.23 W / cm 2 .

[0153] Figure 9The product quality photo of Application Example 10 is shown. It can be seen from the figure that a 10g-level catalyst can be produced according to the method of the present invention, and the yield of batch production can be calculated to be 99.6%.

[0154] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Based on the core technical concepts disclosed herein (including but not limited to active component loading strategies, alloy structure control methods, and carrier optimization solutions), technical solutions obtained by those skilled in the art by adjusting metal ratios, replacing co-catalyst elements, or improving carrier morphology, while adhering to the fundamental principles of novelty and inventiveness, fall within the scope of reasonable extensions of the present invention under the principle of equivalents. It should be noted that any equivalent substitution or partial optimization based on the essential technical features recited in the claims of the present invention shall be included in the scope of patent protection.

Claims

1. A method for preparing a zinc-doped subnanoscale platinum-based catalyst, characterized in that: A platinum precursor, a transition metal element precursor, a zinc precursor, a small molecule reducing agent and a catalyst carrier are added to a container containing a reaction solvent, uniformly dispersed by ultrasonication, and then heated for reaction. The reaction product is washed, centrifuged, acid-washed, washed again, centrifuged, and finally dried to obtain the zinc-doped sub-nanoscale platinum-based catalyst.

2. The method for preparing a zinc-doped subnanoscale platinum-based catalyst according to claim 1, wherein: The platinum precursor is at least one of platinum acetylacetonate and chloroplatinic acid hexahydrate, the transition metal element precursor is at least one of basic cobalt carbonate and basic nickel carbonate, the zinc precursor is zinc acetylacetonate, and the small molecule reducing agent is at least one of ascorbic acid and glucose; the reaction solvent is at least one of benzyl alcohol and ethylene glycol.

3. The method for preparing a zinc-doped sub-nanoscale platinum-based catalyst according to claim 1, wherein: The molar ratio of the platinum precursor to the transition metal precursor is 1-3:1; the molar ratio of the platinum precursor to the zinc precursor is 1-6:

1.

4. The method for preparing a zinc-doped sub-nanoscale platinum-based catalyst according to claim 1, wherein: The catalyst carrier is at least one of Ketjenblack-300 and Ketjenblack-600 carbon powders.

5. The method for preparing a zinc-doped sub-nanoscale platinum-based catalyst according to claim 1, wherein: The heating reaction temperature is 160-200° C., and the reaction time is 5-10 h.

6. The method for preparing a zinc-doped sub-nanoscale platinum-based catalyst according to claim 1, wherein: The washing is performed using a mixed solution of ethanol and water; and the pickling is performed using a nitric acid solution with a concentration of 0.5-2 mol / L.

7. A zinc-doped subnanoscale platinum-based catalyst, characterized in that: Prepared by the preparation method according to any one of claims 1 to 6.

8. The zinc-doped sub-nanoscale platinum-based catalyst according to claim 7, characterized in that: The average particle size of the catalyst is 1~4nm.

9. The zinc-doped sub-nanoscale platinum-based catalyst according to claim 7, characterized in that: The zinc element is doped into the gap of platinum metal, and the lattice expansion is used to reduce the size of nanoparticles and optimize the electronic structure of Pt, thus weakening the ORR process. Adsorption of intermediates.

10. The use of a zinc-doped sub-nanoscale platinum-based catalyst according to claim 7, characterized in that: Application in the cathode oxygen reduction reaction of fuel cells and membrane electrode of proton exchange membrane fuel cell devices.

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