Platinum-rhenium alloy catalyst, method of making and fuel cell
By synthesizing platinum-rhenium alloy catalysts in a two-step process, the problem of the difficulty in alloying platinum and rhenium in traditional methods has been solved, enabling the preparation of highly efficient fuel cell catalysts, reducing the use of precious metals and improving catalytic performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA UNIV OF PETROLEUM (BEIJING)
- Filing Date
- 2023-11-10
- Publication Date
- 2026-06-23
AI Technical Summary
In existing technologies, platinum-carbon catalysts are limited by the reserves of the precious metal platinum, and rhenium is difficult to reduce in traditional wet chemical methods, which makes the preparation of platinum-rhenium alloy catalysts difficult, especially the alloying of platinum and rhenium in the one-pot process.
A two-step method was adopted to synthesize platinum-rhenium alloy catalysts. First, Pt/C precursors were synthesized via microwave-assisted ethylene glycol method. Then, the precursors were reacted with phosphorus source and rhenium precursor in aqueous phase. After evaporation and drying, the precursors were calcined at high temperature to alloy rhenium with platinum, thus solving the problems of reduction and alloying of platinum and rhenium.
The prepared PtRe/PC catalyst not only reduces the use of platinum resources and improves catalytic activity, but is also suitable for large-scale production and has excellent oxygen reduction reaction performance.
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Figure CN117558927B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fuel cell cathode catalyst preparation, specifically relating to a platinum-rhenium alloy catalyst, its preparation method, and a fuel cell. Background Technology
[0002] Hydrogen energy, due to its diverse sources, clean and low-carbon nature, flexibility, high efficiency, and wide range of applications, is considered one of the most promising clean energy sources of the 21st century. A fuel cell is an energy conversion device that efficiently utilizes hydrogen energy. It boasts high conversion efficiency and zero emissions, directly converting the chemical energy stored in fuel into electrical energy through an electrochemical reaction. Its basic reactions involve oxygen reduction at the cathode and fuel oxidation at the anode. The kinetics of the oxygen reduction reaction at the cathode are extremely slow; therefore, the amount of catalyst required at the cathode is much higher than at the anode. Developing highly active and durable fuel cell oxygen reduction electrocatalysts is crucial for the widespread application of fuel cell technology.
[0003] Currently, platinum-carbon (Pt / C) catalysts are the most widely used commercial fuel cell catalysts. Their simple structure facilitates large-scale production. However, due to the limited reserves of precious metal platinum, there is a need to develop high-efficiency fuel cell catalysts with low platinum loading. Among these, the alloying of platinum with other metals has been proven to be an effective means to improve catalytic performance while reducing the amount of platinum used. The enhanced activity of Pt-based alloy catalysts mainly stems from the alteration of the geometric and electronic structures of Pt atoms by other metals, and different metals produce different effects based on their own properties.
[0004] Rhenium (Re) is relatively inexpensive and has been used in electronic devices, catalysis, aerospace, and other fields. In electrocatalysis, Re exhibits catalytic activity close to that of Pt, but with a lower redox potential. The E / V ratio of 0.368 limits its application. Re is difficult to reduce in traditional wet chemical methods, especially platinum-rhenium alloys, which are difficult to synthesize in one pot in one step. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention provides a platinum-rhenium alloy catalyst, its preparation method, and a fuel cell. The PtRe / PC catalyst is synthesized via a two-step method: first, a Pt / C precursor is synthesized via a microwave-assisted ethylene glycol method; second, the Pt / C precursor, along with a phosphorus source and a rhenium precursor, is impregnated in an aqueous phase, followed by evaporation to obtain a dried product. This dried product is then calcined at high temperature under a specific atmosphere to fully alloy the rhenium precursor with platinum, yielding a phosphorus-doped PtRe / PC catalyst. This two-step synthesis method solves the problem of simultaneous reduction of platinum and rhenium in one-pot wet chemical methods. The decomposition products of the phosphorus source at high temperature drive the reduction of rhenium and its alloying with platinum. This method is simple, and the resulting PtRe / PC catalyst can serve as a highly efficient platinum-based catalyst for fuel cells.
[0006] In a first aspect, the present invention provides a method for preparing a platinum-rhenium alloy catalyst, comprising the following steps:
[0007] (1) The carbon support, platinum source and alkaline substance were dispersed in ethylene glycol and subjected to microwave reaction. After the reaction was completed, the solution was acidified and deposited. After washing with water and drying, the Pt / C precursor was obtained.
[0008] (2) The Pt / C precursor, phosphorus source, and rhenium precursor are dispersed in water and subjected to ultrasonic treatment. After treatment, they are evaporated and ground to obtain platinum-rhenium alloy catalyst precursor.
[0009] (3) The platinum-rhenium alloy catalyst precursor is calcined under an inert atmosphere and then ground to obtain the platinum-rhenium alloy catalyst.
[0010] In the above-mentioned method for preparing platinum-rhenium alloy catalyst, the carbon support can be carbon black, specifically at least one of Vulcan XC-72R, EC-300J, EC-600J, and BP2000;
[0011] The platinum source may be at least one of chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, and platinum acetylacetonate.
[0012] The alkaline substance may be at least one of sodium hydroxide, potassium hydroxide, and ammonia water;
[0013] The molar ratio of the platinum source to the alkaline substance can be 1:(20-110), specifically 1:20, 1:50, 1:80 or 1:110;
[0014] The total mass ratio of the carbon support, the platinum source, and the alkaline substance to the volume ratio of the ethylene glycol is (2-20) mg:1 mL, specifically (5-10) mg:1 mL, 9.2 mg:1 mL, 13.7 mg:1 mL, 6.3 mg:1 mL, 5.4 mg:1 mL, 7 mg:1 mL, and 7.2 mg:1 mL.
[0015] In at least one embodiment of the present invention, the step of dispersing the carbon support, platinum source, and alkaline substance in ethylene glycol is as follows: dispersing the carbon support in ethylene glycol, adding an ethylene glycol solution of the platinum source dropwise while stirring, followed by adding an ethylene glycol solution of the alkaline substance dropwise; wherein, for every 80 mg of the carbon support dispersed in (25-50) mL of ethylene glycol (e.g., 25 mL, 35 mL, or 50 mL), the concentration of the ethylene glycol solution of the platinum source is 4 mg. Pt / mL, the concentration of the ethylene glycol solution of the alkaline substance is 1mol / L;
[0016] The power of the microwave reaction can be 600-900W, specifically 700-900W, 700W, or 900W; the temperature can be 130℃-190℃, specifically 140-180℃, 140℃, 160℃, or 180℃; and the time can be 2min-30min, specifically 2-10min, 2min, 5min, or 10min.
[0017] In the above-mentioned method for preparing platinum-rhenium alloy catalyst, preferably, in the acidification deposition step, acid is added to the solution to adjust the pH value of the solution to 2-4, such as 2, 3 or 4;
[0018] The acid may be at least one of dilute hydrochloric acid, dilute nitric acid, and dilute sulfuric acid, and the concentration may be 0.5 mol / L;
[0019] The acidification deposition time can be 5 to 24 hours, specifically 20 hours, 10 hours, 15 hours or 24 hours;
[0020] The drying process can specifically be freeze drying or vacuum drying, and the temperature for vacuum drying can specifically be 60-70℃, 60℃, or 70℃.
[0021] In the above-mentioned method for preparing platinum-rhenium alloy catalyst, the phosphorus source may be at least one of phosphoric acid, sodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium hypophosphite.
[0022] The rhenium precursor may be at least one of perrhenic acid, sodium perrhenate, rhenium trichloride, and rhenium oxide.
[0023] The molar ratio of the phosphorus source to the rhenium precursor can be 1:(0.1-2), specifically 1:0.4, 1:1, 3:1 or 2:1.
[0024] In the above-mentioned method for preparing platinum-rhenium alloy catalyst, the total mass of the Pt / C precursor, the phosphorus source, and the rhenium precursor, and the volume of water, can be (5-30) mg: 1 mL, specifically (10-12 mg): 1 mL, 10.5 mg: 1 mL, 11.1 mg: 1 mL, 11.3 mg: 1 mL, 10.7 mg: 1 mL, or 10.1 mg: 1 mL;
[0025] In at least one embodiment of the present invention, the step of dispersing the Pt / C precursor with a phosphorus source and a rhenium precursor in water is as follows: adding an aqueous solution of the phosphorus source and an aqueous solution of the rhenium source to the aqueous suspension of the Pt / C precursor; wherein the concentration of the aqueous solution of the phosphorus source is 0.1 mol / L, the concentration of the aqueous solution of the rhenium source is 0.1 mol / L, and the concentration of the Pt / C precursor suspension is 10 mg / mL;
[0026] The power of the ultrasonic treatment can be 500-1000W, such as 500W, and the time can be 30-120 minutes, such as 120 minutes;
[0027] The evaporation process can be carried out at 60℃ to 70℃, such as 60℃ or 70℃.
[0028] In the above-mentioned method for preparing platinum-rhenium alloy catalyst, the inert atmosphere is nitrogen, argon, or a hydrogen-argon mixture;
[0029] The calcination treatment conditions are as follows: the temperature is increased to 600-1100℃ (e.g., 700℃, 900℃, 1100℃, 800℃ or 600℃) at a heating rate of 2-5℃ / min (e.g. 5℃ / min), and held for 1-4 hours (e.g. 1-2 hours, 2 hours, 1 hour, 1.5 hours).
[0030] In the above-described method for preparing the platinum-rhenium alloy catalyst, the total mass fraction of platinum and rhenium metals, based on the total amount of the platinum-rhenium alloy catalyst, can be 10% to 40%, specifically 18% to 27%, 25.54%, 18.77%, 18.85%, 26.81%, 26.77%, or 26.89%. In the platinum-rhenium alloy catalyst, platinum-rhenium alloy nanoparticles are uniformly dispersed on a carbon support.
[0031] In the above-mentioned method for preparing the platinum-rhenium alloy catalyst, the molar ratio of platinum to rhenium can be (1-3):1, specifically (1-2.5):1, 2.5:1, 1:1, or 2:1. In the platinum-rhenium alloy catalyst, the two metals platinum and rhenium can be fully alloyed.
[0032] In the above-mentioned method for preparing platinum-rhenium alloy catalyst, the platinum-rhenium alloy catalyst is a platinum-rhenium alloy catalyst for fuel cells.
[0033] Secondly, the present invention provides a platinum-rhenium alloy catalyst prepared by the method described in any one of the above claims.
[0034] Thirdly, the present invention provides a hydrogen fuel cell, comprising a cathode, an anode, and an electrolyte, characterized in that: the cathode comprises the aforementioned platinum-rhenium alloy catalyst.
[0035] Compared with the prior art, the present invention has the following beneficial effects:
[0036] (1) This invention prepares a platinum-rhenium alloy catalyst in two steps. By pyrolyzing a phosphorus source at high temperature, rhenium is alloyed with platinum, which solves the problem that the difference in reduction potential between platinum and rhenium makes it difficult to reduce them simultaneously, and provides a new approach for the preparation of platinum-rhenium alloys.
[0037] (2) The present invention uses relatively inexpensive rhenium and platinum to alloy, and the prepared platinum-rhenium alloy catalyst not only reduces the use of platinum resources, but also the introduction of rhenium regulates the electronic structure of platinum and improves the catalytic ability.
[0038] (3) The phosphorus-doped carbon support of the electrocatalyst of the present invention contains heteroatoms of phosphorus, which can not only create new active sites, but also enhance the anchoring ability of the support to platinum and rhenium nanoparticles.
[0039] (4) The preparation method of the present invention is green and environmentally friendly, and is also suitable for large-scale production. Attached Figure Description
[0040] Figure 1 This is a process flow diagram of the preparation method of platinum-rhenium alloy catalyst for fuel cells in an embodiment of the present invention.
[0041] Figure 2 The image shows the XRD pattern of the PtRe / PC catalyst prepared in Example 1.
[0042] Figure 3 The linear polarization curve of the oxygen reduction reaction of the PtRe / PC catalyst prepared in Example 1 is shown. Detailed Implementation
[0043] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.
[0044] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; and the materials and reagents used are commercially available unless otherwise specified.
[0045] Mass activity (MA, A / mg) in the following examplesPt The calculation formula for ) is as follows:
[0046] 1 / j = 1 / j k +1 / j L
[0047] MA = j k *S / M Pt
[0048] Where j represents the experimentally measured current density (mA / cm²). 2 );j k Represents dynamic current density (mA / cm²) 2 );j L It is the experimentally measured limiting current diffusion density (mA / cm²). 2 S is the electrode area (cm²) 2 M Pt It is the platinum loading (g).
[0049] Example 1
[0050] The PtRe / PC alloy catalyst was prepared according to the flowchart shown in Figure 1. The specific steps are as follows:
[0051] (1) Take 80 mg of Vulcan XC-72R carbon black and ultrasonically disperse it in 25 mL of ethylene glycol for 30 min. During the stirring process, add 5 mL of 4 mg carbon black dropwise. Pt A 1 mol / L sodium hydroxide-ethylene glycol solution was added dropwise, followed by 5 mL of 1 mol / L sodium hydroxide-ethylene glycol solution (the molar ratio of chloroplatinic acid to sodium hydroxide was 1:50). The homogeneous slurry was then transferred to a microwave reactor and reacted at 160°C for 2 min at a power of 900 W.
[0052] (2) After the reaction solution is naturally cooled to room temperature, 0.5 mol / L dilute sulfuric acid solution is added to adjust the pH to about 2. Platinum nanoparticles are deposited in an acidic environment for 20 h. Then, the solution is rinsed with a large amount of deionized water and Pt / C precursor is obtained by freeze drying.
[0053] (3) Take 1 mL of sodium dihydrogen phosphate solution with a concentration of 0.1 mol / L and 0.4 mL of rhenium trichloride solution with a concentration of 0.1 mol / L, add them to 10 mL of Lt / C precursor suspension (with a concentration of 10 mg / mL) and sonicate for 120 min at a power of 500 W. Then dry at 60 °C and grind and crush.
[0054] (4) The powder was calcined at 700℃ for 120 min under N2 atmosphere with a heating rate of 5℃ / min, and then naturally cooled to room temperature. The powder was then ground to obtain the PtRe / PC alloy catalyst (the total mass fraction of platinum and rhenium metals was 25.54 wt% and the molar ratio of platinum to rhenium was 2.49:1).
[0055] The XRD pattern of the PtRe / PC alloy catalyst prepared in this embodiment is shown below. Figure 2 ,from Figure 2 It can be seen that the PtRe / PC alloy catalyst still exhibits the face-centered cubic structure of the platinum lattice, and the introduction of rhenium on the surface does not cause any change in the platinum lattice. The contents of platinum and rhenium were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), and the total mass fraction of platinum and rhenium and the molar ratio of platinum and rhenium are summarized in Table 1. The above tests indicate that the platinum alloy catalyst was successfully prepared.
[0056] The ORR catalytic activity of the PtRe / PC alloy catalyst prepared in this embodiment was tested under the following conditions: 2.5 mg of catalyst sample was dispersed in 1 mL of a 3:1 mixture of isopropanol and water, and 20 μL of 0.5 wt% Nafion solution was added as a binder. The mixture was then sonicated for 1 hour to form a homogeneous catalyst ink. 10 μL of the catalyst ink was transferred to a rotating disk electrode and dried. A standard three-electrode system was used in an O2-saturated 0.1 M HClO4 electrolyte (Hg / HgSO4 as the reference electrode, platinum wire as the counter electrode, and a rotating disk electrode (5 mm in diameter) as the working electrode). The ORR polarization curve of the PtRe / PC alloy catalyst prepared in this embodiment is shown in [Figure number missing]. Figure 3 ,from Figure 3 It can be seen that the half-wave potential (E) of the PtRe / PC alloy catalyst prepared in this embodiment is... 1 / 2 =0.8622V (relative to the standard hydrogen electrode), the mass activity (MA) is 0.382A / mg. Pt This indicates that the PtRe / PC alloy catalyst in this system has excellent ORR catalytic activity.
[0057] Example 2
[0058] The PtRe / PC alloy catalyst was prepared according to the flowchart shown in Figure 1. The specific steps are as follows:
[0059] (1) Take 80 mg of Vulcan XC-72R carbon black and ultrasonically disperse it in 25 mL of ethylene glycol for 30 min. During the stirring process, add 5 mL of 4 mg carbon black dropwise. PtA chloroplatinic acid-ethylene glycol solution of 1 mol / L was added, followed by 11 mL of a 1 mol / L sodium hydroxide-ethylene glycol solution (the molar ratio of chloroplatinic acid to sodium hydroxide was 1:110). The homogeneous slurry was then transferred to a microwave reactor and reacted at 180°C for 5 min at a power of 900 W.
[0060] (2) After the reaction solution is naturally cooled to room temperature, 0.5 mol / L dilute nitric acid solution is added to adjust the pH to about 3. Platinum nanoparticles are deposited in an acidic environment for 20 h. Then, the solution is rinsed with a large amount of deionized water and Pt / C precursor is obtained by freeze drying.
[0061] (3) Take 1 mL of 0.1 mol / L disodium hydrogen phosphate solution and 1 mL of 0.1 mol / L perrhenic acid solution, add them to 10 mL of Pt / C precursor suspension (concentration of 10 mg / mL) and sonicate for 120 min at 500 W. Then dry at 60 °C and grind.
[0062] (4) The powder was calcined at 900℃ for 120 min under an argon atmosphere with a heating rate of 5℃ / min, and then naturally cooled to room temperature. The powder was then ground to obtain the PtRe / PC alloy catalyst (the total mass fraction of platinum and rhenium metals was 18.77wt% based on the total amount of platinum-rhenium alloy catalyst, and the molar ratio of platinum to rhenium was 1.02:1).
[0063] Example 3
[0064] The PtRe / PC alloy catalyst was prepared according to the flowchart shown in Figure 1. The specific steps are as follows:
[0065] (1) Take 80 mg of Vulcan XC-72R carbon black and ultrasonically disperse it in 25 mL of ethylene glycol for 30 min. During the stirring process, add 5 mL of 4 mg carbon black dropwise. Pt A chloroplatinic acid-ethylene glycol solution of 1 mol / L was added, followed by 2 mL of a 1 mol / L potassium hydroxide-ethylene glycol solution (the molar ratio of chloroplatinic acid to potassium hydroxide was 1:20). The homogeneous slurry was then transferred to a microwave reactor and reacted at 140°C for 10 min at a power of 900 W.
[0066] (2) After the reaction solution is naturally cooled to room temperature, 0.5 mol / L dilute nitric acid solution is added to adjust the pH to about 3. Platinum nanoparticles are deposited in an acidic environment for 10 h. Then, the solution is rinsed with a large amount of deionized water and dried under vacuum at 70 °C to obtain the Pt / C precursor.
[0067] (3) Take 2 mL of 0.1 mol / L phosphoric acid solution and 1 mL of 0.1 mol / L sodium perrhenate solution, add them to 10 mL of Pt / C precursor suspension (concentration of 10 mg / mL) and sonicate for 120 min at 500 W. Then dry at 60 °C and grind.
[0068] (4) The powder was calcined at 1100℃ for 60 min under an argon atmosphere with a heating rate of 5℃ / min, and then naturally cooled to room temperature. The powder was then ground to obtain the PtRe / PC alloy catalyst (the total mass fraction of platinum and rhenium metals was 18.85wt% and the molar ratio of platinum to rhenium was 0.98:1).
[0069] Example 4
[0070] The PtRe / PC alloy catalyst was prepared according to the flowchart shown in Figure 1. The specific steps are as follows:
[0071] (1) Take 80 mg of EC-300J carbon black and ultrasonically disperse it in 50 mL of ethylene glycol for 30 min. During the stirring process, add 5 mL of 4 mg carbon black. Pt A 1 mol / L chloroplatinic acid-ethylene glycol solution was added, followed by 5 mL of a 1 mol / L potassium hydroxide-ethylene glycol solution (the molar ratio of chloroplatinic acid to potassium hydroxide was 1:50). The homogeneous slurry was then transferred to a microwave reactor and reacted at 140°C for 10 min at a power of 900 W.
[0072] (2) After the reaction solution is naturally cooled to room temperature, 0.5 mol / L dilute hydrochloric acid solution is added to adjust the pH to about 4. Platinum nanoparticles are deposited in an acidic environment for 15 h. Then, the solution is rinsed with a large amount of deionized water and dried under vacuum at 60 °C to obtain the Pt / C precursor.
[0073] (3) Take 1.5 mL of 0.1 mol / L phosphoric acid solution and 0.5 mL of 0.1 mol / L sodium perrhenate solution, add them to 10 mL of Pt / C precursor suspension (concentration of 10 mg / mL) and sonicate for 120 min at 500 W. Then dry at 70 °C and grind.
[0074] (4) The powder was calcined at 800°C for 90 min in a hydrogen-argon mixed atmosphere at a heating rate of 5°C / min, and then naturally cooled to room temperature. The powder was then ground to obtain the PtRe / PC alloy catalyst (the total mass fraction of platinum and rhenium metals was 26.81 wt% and the molar ratio of platinum to rhenium was 2.00:1).
[0075] Example 5
[0076] The PtRe / PC alloy catalyst was prepared according to the flowchart shown in Figure 1. The specific steps are as follows:
[0077] (1) Take 80 mg of EC-300J carbon black and ultrasonically disperse it in 50 mL of ethylene glycol for 30 min. During the stirring process, add 5 mL of 4 mg carbon black. Pt Add 8 mL of chloroplatinic acid-ethylene glycol solution, followed by 8 mL of 1 mol / L potassium hydroxide-ethylene glycol solution (the molar ratio of chloroplatinic acid to potassium hydroxide is 1:80). Transfer the homogeneous slurry to a microwave reactor and react at 140°C for 10 min with a power of 900 W.
[0078] (2) After the reaction solution is naturally cooled to room temperature, 0.5 mol / L dilute hydrochloric acid solution is added to adjust the pH to about 4. Platinum nanoparticles are deposited in an acidic environment for 15 h. Then, the solution is rinsed with a large amount of deionized water and dried under vacuum at 60 °C to obtain the Pt / C precursor.
[0079] (3) Take 1.5 mL of 0.1 mol / L phosphoric acid solution and 0.5 mL of 0.1 mol / L sodium perrhenate solution, add them to 10 mL of Pt / C precursor suspension (concentration of 10 mg / mL) and sonicate for 120 min at 500 W. Then dry at 70 °C and grind.
[0080] (4) The powder was calcined at 800°C for 90 min in a hydrogen-argon mixed atmosphere at a heating rate of 5°C / min, and then naturally cooled to room temperature. The powder was then ground to obtain the PtRe / PC alloy catalyst (the total mass fraction of platinum and rhenium metals was 26.77 wt% and the molar ratio of platinum to rhenium was 2.01:1).
[0081] Example 6
[0082] The PtRe / PC alloy catalyst was prepared according to the flowchart shown in Figure 1. The specific steps are as follows:
[0083] (1) Take 80 mg of BP2000 carbon black and ultrasonically disperse it in 35 mL of ethylene glycol for 30 min. During the stirring process, add 5 mL of 4 mg carbon black dropwise. Pt A 1 mol / L chloroplatinic acid-ethylene glycol solution was added, followed by 5 mL of a 1 mol / L potassium hydroxide-ethylene glycol solution (the molar ratio of chloroplatinic acid to potassium hydroxide was 1:50). The homogeneous slurry was then transferred to a microwave reactor and reacted at 160°C for 10 min at a power of 700 W.
[0084] (2) After the reaction solution is naturally cooled to room temperature, 0.5 mol / L dilute hydrochloric acid solution is added to adjust the pH to about 2. Platinum nanoparticles are deposited in an acidic environment for 24 hours. Then, the solution is rinsed with a large amount of deionized water and dried under vacuum at 60°C to obtain the Pt / C precursor.
[0085] (3) Take 1 mL of sodium dihydrogen phosphate solution with a concentration of 0.1 mol / L and 0.5 mL of rhenium trichloride solution with a concentration of 0.1 mol / L, add them to 10 mL of Pt / C precursor suspension (with a concentration of 10 mg / mL) and sonicate for 120 min at a power of 600 W. Then dry at 60 °C and grind and crush.
[0086] (4) The powder was calcined at 600℃ for 120 min under an argon atmosphere with a heating rate of 10℃ / min, and then naturally cooled to room temperature. The powder was then ground to obtain the PtRe / PC alloy catalyst (the total mass fraction of platinum and rhenium metals was 26.89 wt% and the molar ratio of platinum to rhenium was 1.98:1).
[0087] Comparative Example 1
[0088] The catalyst was prepared according to Example 1, except that no phosphorus source was added. The specific steps are as follows:
[0089] (1) Take 80 mg of Vulcan XC-72R carbon black and ultrasonically disperse it in 25 mL of ethylene glycol for 30 min. During the stirring process, add 5 mL of 4 mg carbon black dropwise. Pt A chloroplatinic acid-ethylene glycol solution of 1 mol / L was added dropwise, followed by 5 mL of sodium hydroxide-ethylene glycol solution of 1 mol / L. The homogeneous slurry was then transferred to a microwave reactor and reacted at 160°C for 2 min at a power of 900 W.
[0090] (2) After the reaction solution is naturally cooled to room temperature, 0.5 mol / L dilute sulfuric acid solution is added to adjust the pH to about 2. Platinum nanoparticles are deposited in an acidic environment for 20 h. Then, the solution is rinsed with a large amount of deionized water and Pt / C precursor is obtained by freeze drying.
[0091] (3) Take 0.4 mL of rhenium trichloride solution with a concentration of 0.1 mol / L, add it to 10 mL of Pt / C precursor suspension (with a concentration of 10 mg / mL) and sonicate for 120 min at a power of 500 W. Then dry it at 60 °C and grind it.
[0092] (4) The powder was calcined at 700°C for 120 min under N2 atmosphere with a heating rate of 5°C / min, and then naturally cooled to room temperature. The powder was then ground to obtain a platinum-based catalyst.
[0093] Comparative Example 2
[0094] The catalyst was prepared according to Example 1, except that no rhenium source was added. The specific steps are as follows:
[0095] (1) Take 80 mg of Vulcan XC-72R carbon black and ultrasonically disperse it in 25 mL of ethylene glycol for 30 min. During the stirring process, add 5 mL of 4 mg carbon black dropwise. Pt A chloroplatinic acid-ethylene glycol solution of 1 mol / L was added dropwise, followed by 5 mL of sodium hydroxide-ethylene glycol solution of 1 mol / L. The homogeneous slurry was then transferred to a microwave reactor and reacted at 160°C for 2 min at a power of 900 W.
[0096] (2) After the reaction solution is naturally cooled to room temperature, 0.5 mol / L dilute sulfuric acid solution is added to adjust the pH to about 2. Platinum nanoparticles are deposited in an acidic environment for 20 h. Then, the solution is rinsed with a large amount of deionized water and Pt / C precursor is obtained by freeze drying.
[0097] (3) Take 1 mL of sodium dihydrogen phosphate solution with a concentration of 0.1 mol / L, add it to 10 mL of Pt / C precursor suspension (with a concentration of 10 mg / mL) and sonicate for 120 min at a power of 500 W. Then dry it at 60 °C, grind and crush it to obtain a platinum-based catalyst.
[0098] (4) The powder was calcined at 700°C for 120 min under N2 atmosphere with a heating rate of 5°C / min, and then naturally cooled to room temperature. The powder was then ground to obtain a platinum-based catalyst.
[0099] Comparative Example 3
[0100] The Pt / C precursor catalyst was prepared according to Example 1, and the specific steps are as follows:
[0101] (1) Take 80 mg of Vulcan XC-72R carbon black and ultrasonically disperse it in 25 mL of ethylene glycol for 30 min. During the stirring process, add 5 mL of 4 mg carbon black dropwise. Pt A chloroplatinic acid-ethylene glycol solution of 1 mol / L was added dropwise, followed by 5 mL of sodium hydroxide-ethylene glycol solution of 1 mol / L. The homogeneous slurry was then transferred to a microwave reactor and reacted at 160°C for 2 min at a power of 900 W.
[0102] (2) After the reaction solution is naturally cooled to room temperature, 0.5 mol / L dilute sulfuric acid solution is added to adjust the pH to about 2. Platinum nanoparticles are deposited in an acidic environment for 20 h. Then, a large amount of deionized water is used to rinse the solution and the Pt / C precursor catalyst is obtained by freeze drying.
[0103] The PtRe / PC alloy catalysts prepared in Examples 1-6 and the catalysts prepared in Comparative Examples 1-3 were used for working electrode testing. The testing methods are described in Example 1, and the results are shown in Table 1.
[0104] Table 1. Comparison of half-wave potential, mass activity, total mass fraction, and platinum-rhenium molar ratio of catalysts prepared in each example.
[0105]
[0106] As can be seen from the table above, the platinum-rhenium alloy catalyst for fuel cells prepared by the process of this invention exhibits excellent electrochemical performance. In particular, the catalyst in Example 1 can achieve a half-wave potential of 0.8622 V and a mass activity of 0.382 mA / mg. Pt (0.9V), and the preparation method is simple and easy to implement, making it suitable for large-scale production.
[0107] Comparative Examples 1 and 2-3 revealed that, compared to platinum catalysts, platinum-rhenium alloy catalysts exhibit superior electrochemical performance due to the addition of rhenium. This invention reduces the use of platinum resources, while the introduction of rhenium modulates the electronic structure of platinum, thereby enhancing catalytic activity.
[0108] Comparing Example 1 and Comparative Examples 1-3, the electrocatalytic performance of the platinum-rhenium alloy catalyst in Example 1 was significantly better than that in Comparative Examples 1-2, while there was no significant difference in the electrochemical performance of Comparative Examples 1-3. This is because the decomposition products of the phosphorus source at high temperature drive the reduction of rhenium and its alloying with platinum. This invention prepares a platinum-rhenium alloy catalyst through a two-step method. By pyrolyzing the phosphorus source at high temperature, rhenium is alloyed with platinum, solving the problem of the difficulty in simultaneous reduction due to the difference in reduction potentials between platinum and rhenium, and providing a new approach for the preparation of platinum-rhenium alloys.
[0109] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including modifications made using conventional techniques known in the art that depart from the scope disclosed herein.
Claims
1. A method for preparing a platinum-rhenium alloy catalyst, comprising the following steps: (1) The carbon support, platinum source and alkaline substance were dispersed in ethylene glycol and subjected to microwave reaction. After the reaction was completed, the solution was acidified and deposited. After washing with water and drying, the Pt / C precursor was obtained. (2) The Pt / C precursor, phosphorus source, and rhenium precursor are dispersed in water and subjected to ultrasonic treatment. After treatment, they are evaporated and ground to obtain platinum-rhenium alloy catalyst precursor. (3) The platinum-rhenium alloy catalyst precursor is calcined in an inert atmosphere and then ground to obtain the platinum-rhenium alloy catalyst.
2. The method for preparing the platinum-rhenium alloy catalyst according to claim 1, characterized in that: The carbon carrier is carbon black; The platinum source is at least one of chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, and platinum acetylacetonate. The alkaline substance is at least one of sodium hydroxide, potassium hydroxide, and ammonia water; The molar ratio of the platinum source to the alkaline substance is 1:(20~110). The total mass ratio of the carbon support, the platinum source, and the alkaline substance to the volume ratio of the ethylene glycol is (2~20) mg: 1 mL; The microwave reaction has a power of 600~900W, a temperature of 130℃~190℃, and a time of 2min~30min.
3. The method for preparing the platinum-rhenium alloy catalyst according to claim 2, characterized in that: The carbon support is at least one of Vulcan XC-72R, EC-300J, EC-600J, and BP2000.
4. The method for preparing the platinum-rhenium alloy catalyst according to any one of claims 1-3, characterized in that: In the acidification deposition step, acid is added to the solution to adjust the pH value of the solution to 2-4; The acid is at least one of dilute hydrochloric acid, dilute nitric acid, and dilute sulfuric acid; The acidification deposition time is 5~24h.
5. The method for preparing the platinum-rhenium alloy catalyst according to any one of claims 1-3, characterized in that: The phosphorus source is at least one of phosphoric acid, sodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium hypophosphite. The rhenium precursor is at least one of perrhenic acid, sodium perrhenate, rhenium trichloride, and rhenium oxide. The molar ratio of the phosphorus source to the rhenium precursor is 1:(0.1~2).
6. The method for preparing the platinum-rhenium alloy catalyst according to any one of claims 1-3, characterized in that: The total mass ratio of the Pt / C precursor, the phosphorus source, and the rhenium precursor to the volume of water is (5~30) mg: 1 mL; The ultrasonic treatment has a power of 500~1000W and a duration of 30~120 minutes.
7. The method for preparing the platinum-rhenium alloy catalyst according to any one of claims 1-3, characterized in that: The inert atmosphere is nitrogen, argon, or a mixture of hydrogen and argon; The calcination treatment conditions are as follows: the temperature is increased to 600-1100℃ at a heating rate of 2-5℃ / min and held for 1-4 hours.
8. The method for preparing the platinum-rhenium alloy catalyst according to any one of claims 1-3, characterized in that: The total mass fraction of platinum and rhenium metals in the platinum-rhenium alloy catalyst is 10% to 40%.
9. The method for preparing the platinum-rhenium alloy catalyst according to any one of claims 1-3, characterized in that: In the platinum-rhenium alloy catalyst, the molar ratio of platinum to rhenium is (1~3):
1.
10. The platinum-rhenium alloy catalyst prepared by the method according to any one of claims 1-9.
11. A hydrogen fuel cell, comprising a cathode, an anode, and an electrolyte, characterized in that: The cathode comprises the platinum-rhenium alloy catalyst of claim 10.