Polyacid ligand modified platinum nanoparticle oxygen reduction electrocatalyst and preparation method thereof
By modifying platinum nanomaterials with multi-acid ligands, the interfacial poisoning problem of oxygen reduction reaction at the cathode of proton exchange membrane fuel cells was solved, achieving high efficiency, low cost, and stable oxygen reduction performance.
Patent Information
- Application Number
- CN202511258286.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-04
- Publication Date
- 2025-12-12
AI Technical Summary
Existing proton exchange membrane fuel cell cathode oxygen reduction reaction (ORR) suffers from high overpotential loss and high cost of precious metal platinum catalysts. Existing technologies have not effectively solved the interface poisoning problem, which leads to high catalyst costs.
Using multi-acid ligands: Platinum nanomaterials are modified with multi-acid ligands, which isolate them from perfluorosulfonate ions through electrostatic repulsion. Combined with multi-walled carbon nanotube supports, this achieves stable dispersion of platinum nanoparticles and enhances catalytic activity and stability.
This study achieved high-efficiency oxygen reduction performance and stability of platinum nanoparticles, reduced overpotential loss, improved catalyst stability and activity, and reduced catalyst cost.
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Figure CN121123306A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of new materials technology, and more specifically relates to an oxygen reduction electrocatalyst of platinum nanoparticles modified with polyacid ligands and its preparation method. Background Technology
[0002] As a new generation of efficient and clean energy conversion system, fuel cell technology has made breakthroughs in recent years in key material development, system integration optimization, and commercial application expansion. Among them, proton exchange membrane fuel cells (PEMFCs) have shown broad application prospects in transportation, distributed power generation, and other fields due to their advantages such as rapid start-up and high power density. However, the large-scale commercialization of PEMFCs still faces significant technical bottlenecks, with the core challenge being the slow kinetics of the cathode oxygen reduction reaction (ORR). This reaction not only suffers from overpotential losses as high as 300mV but also heavily relies on precious metal platinum (Pt)-based catalysts, resulting in high system costs. Statistics show that the cost of the cathode catalyst accounts for more than 40% of the total cost of the fuel cell stack, which severely restricts the industrialization process of PEMFCs. Therefore, developing ORR electrocatalysts that combine high activity and low cost has become a key research focus.
[0003] In-depth research revealed that ORR catalysts face severe interfacial poisoning problems in actual working environments. The core mechanism is as follows: (1) The sulfonate groups of the perfluorosulfonic acid ionomer selectively adsorb onto the active sites of the Pt(111) crystal plane, forming a dense monolayer with a coverage of over 80% in the 0.7-0.9V vs. RHE working potential range; (2) The cations in the electrolyte (such as Na) + Ca 2+ (e.g., sulfonate groups) can form a complex adsorption layer with sulfonate groups through electrostatic interactions, further exacerbating the poisoning effect. This interfacial poisoning leads to a significant decline in three key performance indicators: in terms of catalytic activity, the mass activity decreases by more than 60% (from 0.3 mg / L). Pt -1 Reduced to 0.12 A mg Pt -1 In terms of reaction kinetics, an increase in overpotential of 50-70 mV alters the Tafel slope from the ideal 60 mV. -1 Degraded to 90mV dec -1 In terms of stability, after 30,000 accelerated durability tests, the electrochemical active area loss exceeded 40%.
[0004] To address this challenge, polyoxometalates (POMs) exhibit significant application potential due to their unique structural properties: 1) their precisely controllable molecular structure (size 1-5 nm) and rich coordination chemistry enable precise modification of metal nanoparticles; 2) excellent proton-electron dual conductivity (proton conductivity > 0.1 S cm⁻¹). -1 The unique co-proton-electron transfer (CPET) mechanism of POMs (high electron transfer number of 0.3-0.5) effectively alleviates interfacial mass transfer limitations; 3) tunable redox properties (reduction potential 0.2-0.8 V vs. NHE) and acid-base properties (pKa 0-5) provide new ideas for optimizing the catalyst / electrolyte interface environment. How to utilize these properties of POMs to design novel composite catalytic materials and overcome the technical bottlenecks of existing ORR catalysts has become a cutting-edge research topic in the field of electrochemical energy. Summary of the Invention
[0005] The purpose of this invention is to provide a multi-acid ligand modification strategy for improving the performance of platinum electrocatalytic oxygen reduction reaction, thereby solving the problem of Pt interface poisoning mentioned in the background art. This invention utilizes multi-acid ligands, leveraging the electrostatic repulsion effect of the high negative charge of the multi-acids to achieve mutual repulsion with perfluorosulfonate ions, resulting in platinum nanomaterials modified with multi-acid ligands. The steric hindrance effect further facilitates the blocking of perfluorosulfonate ions, thus solving the problems existing in the prior art.
[0006] To achieve the above objectives, the present invention provides the following solution:
[0007] One of the technical solutions of the present invention is to provide a supported electrocatalyst of platinum nanomaterials modified with polyacid ligands, wherein the supported electrocatalyst comprises a multi-walled carbon nanotube conductive support with a high specific surface area, and platinum nanomaterials modified with polyacid ligands supported on the conductive support.
[0008] Furthermore, the polyacid ligand is characterized in that it comprises silicotungstic acid [α-SiW9O] 34 ] 10- (abbreviation: SiW9), [γ-SiW 10 O 36 ] 8- (abbreviation: SiW10), [β2-SiW 11 O 39 ] 8- (Abbreviation: SiW11), [SiW 12 O 40 ] 4- (Abbreviation: SiW12).
[0009] The second technical solution of this invention provides a method for preparing a supported electrocatalyst of platinum nanomaterials modified with the above-mentioned polyacid ligands, comprising the following steps:
[0010] The polyacid ligands were dissolved in water at 0-5℃ to obtain a ligand solution;
[0011] A platinum nanomaterial precursor was added to the ligand solution and stirred to obtain a mixed solution.
[0012] Sodium borohydride (NaBH4) solution was added dropwise to the mixed solution, followed by the addition of a multi-walled carbon nanotube conductive support. The resulting solid product was purified and dried to obtain the supported electrocatalyst.
[0013] The concentration of the sodium borohydride (NaBH4) solution is 0.01–0.05 M.
[0014] Furthermore, the concentration of the polyacid ligand in the ligand solution is 1–4 mM.
[0015] Furthermore, the molar ratio of the polyacid ligand to the platinum nanomaterial precursor is 0.3 to 4.
[0016] Furthermore, the molar ratio of the platinum nanomaterial precursor to the reducing agent in the sodium borohydride (NaBH4) solution is 0.02–0.3.
[0017] Furthermore, the platinum nanomaterial precursor is K2PtCl6.
[0018] Furthermore, the purification step includes: dispersing the solid product in water, stirring and filtering, and then washing with water 2 to 3 times.
[0019] Furthermore, the drying process is vacuum drying.
[0020] Based on the present invention, a low-temperature water bath (0-5℃ water) environment is used to inhibit the decomposition and isomerization of unstable polyacid ligands, and the instantaneous reduction of sodium borohydride is used to avoid the decomposition, damage or isomerization transformation that may be caused by long-term and violent effects of light, heat, electricity, etc. on polyacid ligands.
[0021] Addressing the issues of easy aggregation, poor binding force, and poor hydrophilicity inherent in platinum nanoparticles, this invention utilizes high specific surface area carriers such as multi-walled carbon nanotubes to suppress aggregation, stabilize dispersion, and increase the active specific surface area of platinum nanoparticles. Simultaneously, during the formation of platinum particles in polyacid ligand-modified platinum nanomaterials, the high negative charge of the polyacid ligands enables the dispersion and aggregation of platinum particles, thereby controlling the size of platinum nanoparticles, obtaining different quantum effects, and achieving stable, high-quality activity. The polyacid ligands create a highly negatively charged shell on the platinum surface; electrostatic repulsion and steric hindrance create a channel between platinum and perfluorosulfonate ions, facilitating further contact between platinum and O2. The electron-depleted oxidized polyacid ligands exhibit extremely strong proton-capturing ability and, with a size approaching the nanometer scale, can extend across the platinum-electrolyte double layer to rapidly capture protons. The polyacid ligands are an excellent proton-electron co-transfer medium, capable of coupling electrons and protons, effectively catalyzing the oxygen reduction reaction.
[0022] The third technical solution of the present invention provides an application of the above-mentioned polyacid ligand-modified platinum nanomaterial supported electrocatalyst as an electrode modification material in the preparation of electrocatalytic reaction electrodes.
[0023] Furthermore, the electrocatalytic reaction includes a cathode oxygen reduction reaction.
[0024] The fourth technical solution of the present invention provides an electrode for cathode oxygen reduction, wherein the active component of the electrode includes the above-mentioned supported electrocatalyst of platinum nanomaterials modified with polyacid ligands.
[0025] Fifth technical solution of the present invention: A method for cathode oxygen reduction, wherein the above-mentioned electrode is used as the working electrode.
[0026] The present invention discloses the following technical effects:
[0027] The supported electrocatalyst of platinum nanomaterials modified with polyacid ligands prepared in this invention has strong cathodic oxygen reduction performance and good potential for electrocatalytic applications.
[0028] Polyoxometalates, as ligands with unique redox properties distinct from traditional ligands such as thiols, were successfully used to modify the surface of metal nanoparticles with high negative charges and multiple vacancies, and then loaded onto a conductive support. The high negative charge of the polyoxometalate ligands enables the dispersion and aggregation of platinum particles, achieving stable and high-quality activity. The polyoxometalate ligands form a highly negatively charged shell on the platinum surface, and the electrostatic repulsion and steric hindrance effect create a channel between platinum and perfluorosulfonate ions, facilitating further contact between platinum and O2. The polyoxometalate ligands exhibit extremely strong proton-capturing ability, and their near-nanoscale size allows for rapid proton capture. Furthermore, the polyoxometalate ligands are superior proton-electron co-transfer mediators, capable of coupling electrons and protons, and effectively catalyzing the oxygen reduction reaction.
[0029] The material prepared by the method of this invention can achieve a half-wave potential of 0.835 V vs. RHE and an A value of 6.93 mA cm⁻¹ with extremely low metal loading. -2 The limiting diffusion current density has a Tafel slope as low as 103.51 mV dec. -1 This indicates a significant improvement in reaction kinetics. Of particular note is that after 10,000 cyclic voltammetric accelerated aging tests, its performance degradation was only 28 mV, demonstrating excellent stability. It shows great application potential for other types of inorganic and organic catalysis and is a pioneer in the development of other types of polyacid and metal nanoparticle nanocatalysts. Attached Figure Description
[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:
[0031] Figure 1 This is a schematic diagram of platinum nanoparticles modified with highly negatively charged, multi-vacancy Keggin-type polyacids and loaded onto carbon nanotubes.
[0032] Figure 2 The images are from a transmission electron microscope (TEM). Figure a shows Pt NPs@SiW9 / CNT; Figure b shows Pt NPs@SiW10 / CNT; Figure c shows Pt NPs@SiW11 / CNT; and Figure d shows Pt NPs@SiW12 / CNT.
[0033] Figure 3 High-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image and elemental mapping EDS surface scan of Pt NPs@SiW10 / CNT, where a is HAADF-STEM and b is EDS.
[0034] Figure 4 Infrared spectra of Pt NPs@SiW9, Pt NPs@SiW10, Pt NPs@SiW11, and Pt NPs@SiW12.
[0035] Figure 5 Linear sweep voltammetry (LSV) curves for oxygen reduction at different electrodes.
[0036] Figure 6 The stability curves of PtNPs@SiW10 / CNT, PtNPs / CNT and commercial platinum-carbon modified electrodes after 10,000 cycles of accelerated voltammetry aging test under cathode oxygen reduction are shown. Detailed Implementation
[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0038] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0039] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0040] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0041] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0042] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.
[0043] In the specific embodiments of the present invention, the room temperature and ambient temperature are both 20-30℃.
[0044] The raw materials and reagents used in the specific embodiments of this invention are all commercially available products.
[0045] It should be noted that the polyoxometalates involved in the specific embodiments of the present invention can be commercially available or self-made without affecting the realization of the technical effect.
[0046] The following are exemplary self-preparation steps for polyacids:
[0047] (1) Polyacid ligands [α-SiW12 O 40 ] 4- Synthesis of (SiW12, a classic Keggin-type polyacid):
[0048] Sodium silicate (Na2SiO3) (1.16526 g, 50 mmol) was dissolved in 10 mL of distilled water at room temperature while being magnetically stirred to form solution A;
[0049] In another 100 mL beaker, sodium tungstate dihydrate (Na2WO4·2H2O) (18.23291 g, 55 mmol) was dissolved in 30 mL of boiling distilled water and stirred magnetically to prepare solution B.
[0050] Subsequently, under vigorous stirring, 16.5 mL of 4M hydrochloric acid (HCl) solution was added dropwise over 5 minutes to boiling solution B to promote the dissolution of tungstic acid precipitate. Then, solution A was added, followed immediately by 5 mL of 4M HCl. The pH was then adjusted to approximately 5-6. The resulting mixture was kept at approximately 100°C for 1 hour. After that, 5 mL of 1M sodium tungstate dihydrate (Na2WO4·2H2O, equivalent to 5 mmol) was added, followed immediately by 8 mL of concentrated HCl. The reaction solution was cooled to room temperature and then filtered. After filtration, the pH was adjusted to approximately 2 using 1M NaOH aqueous solution. Finally, approximately 50 g of solid sodium chloride (NaCl) was added to the mixture. After removing any possible potassium salts by filtration, the mixture was dried in air to obtain the target SiW12 product.
[0051] (2) Polyacid ligand [β2-SiW 11 O 39 ] 8- Synthesis of (SiW11, a uni-deficient Keggin-type polyacid):
[0052] Sodium metasilicate Na₂SiO₃ (11.6526 g, 50 mmol) was dissolved in 100 mL of distilled water (solution A). Sodium tungstate Na₂WO₄·2H₂O (182.3291 g, 0.55 mol) was dissolved in 300 mL of water (solution B). 165 mL of 4M HCl was added to this solution at a rate of 1 mL per addition over 10 min, with vigorous stirring (this locally forms hydrated tungstate, which slowly disappears). Then, solution A was poured into tungstate solution B. The pH was adjusted to between 5 and 6 by immediately adding 4M HCl solution (approximately ~40 mL). This pH was maintained for 100 min by adding small amounts of 4M HCl. Then, solid potassium chloride (90 g) was added to the solution, and the mixture was gently stirred to obtain a white precipitate. After 15 min, the precipitate was obtained by filtration. Further purification: the product was dissolved in 850 mL of water; insoluble substances were rapidly removed by filtration; and the salt was precipitated again by adding solid KCl (8 g). Wash with two 50 ml portions of 2 M KCl solution and air dry at room temperature to obtain a white solid β2-SiW11.
[0053] (3) Polyacid ligand [γ-SiW] 10 O 36 ] 8- Synthesis of (SiW10, a divacant Keggin-type polyacid):
[0054] Put K8[β2-SiW 11 O 39 1.5 g of 14H₂O (0.5 mmol) was dissolved in 15 mL of water maintained at 25 °C, and insoluble substances were removed by filtration. After 16 min, the pH of the solution was rapidly adjusted to 9.1 by adding 2 M K₂CO₃ aqueous solution. The pH of the solution was maintained at this value for exactly 16 min by adding K₂CO₃ solution. Then, solid potassium chloride (KCl) (4 g) was added to precipitate the solution. During precipitation (10 min), the pH had to be maintained at 9.1 by adding small amounts of K₂CO₃ solution. The solid was removed by filtration, washed with 1 M KCl solution, and then air-dried.
[0055] (4) Polyacid ligand [α-SiW9O 34 ] 10- Synthesis of (SiW9, a triple-vacancy Keggin-type polyacid):
[0056] Sodium tungstate hydrate Na2WO4·2H2O (55 mmol) and sodium metasilicate Na2SiO3 (50 mmol) were dissolved in 200 mL of hot water (80-100 °C) and placed in a 1.2 L beaker with a magnetic stir bar to obtain a mixed solution.
[0057] 13 mL of 6M hydrochloric acid (HCl) was added dropwise to the above mixture, stirred for 30 min, and then boiled to concentrate to 30 mL. Unreacted silica was removed by filtration to obtain the concentrated solution.
[0058] In a separate beaker, dissolve 5g of anhydrous sodium carbonate in 15mL of water. Slowly add the anhydrous sodium carbonate solution to the concentrate and stir gently. The precipitate slowly forms. After 1 hour, filter to obtain the solid. Then stir with 100mL of 4M NaCl solution, filter again, and wash with two 10mL portions of ethanol and 10mL of diethyl ether in sequence. Dry under vacuum to obtain SiW9.
[0059] Example 1
[0060] The preparation steps of the supported catalyst of polyoxometalate modified platinum nanomaterials include:
[0061] SiW10 (100 μmol) was dissolved in 55 mL of water in an ice bath (~3℃), and then K2PtCl6 (51.11 mg, containing 105 μmol of Pt) was added. After stirring the solution for 60 min, freshly prepared 0.03 M NaBH4 (5 mL, 150 μmol) ice-water solution was added dropwise over 10 min. Immediately after adding NaBH4, high specific surface area conductive support carbon nanotubes (CNTs) (100 mg) were added. The mixture was stirred for 20 min, and solid-liquid separation was performed to obtain the crude catalyst.
[0062] The crude catalyst was dispersed in water and stirred for 10 minutes. Then it was filtered and washed with water to obtain the target material. The obtained material was dried under vacuum (60°C) to obtain the supported catalyst, denoted as Pt NPs@SiW10 / CNT.
[0063] Figure 1 This is a schematic diagram of platinum nanoparticles modified with highly negatively charged, multi-vacancy Keggin-type polyacid (SiW9) and loaded onto carbon nanotubes (PtNPs@SiW9 / CNT).
[0064] Figure 2 The images are obtained using transmission electron microscopy (TEM). Figure a shows Pt NPs@SiW9 / CNT; Figure b shows Pt NPs@SiW10 / CNT; Figure c shows Pt NPs@SiW11 / CNT; and Figure d shows Pt NPs@SiW12 / CNT. As can be seen from the figures, the synthesized catalysts have a size of 2 nm and are uniformly distributed on the surface of the multi-walled carbon nanotubes.
[0065] Figure 3The images show high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images and elemental mapping EDS surface scans of Pt NPs@SiW10 / CNT, where a is the HAADF-STEM image and b is the EDS image. The images show that polyacids are modified on the surface of the platinum nanoparticles.
[0066] Example 2
[0067] The preparation steps of supported catalysts made from polyoxometalate-modified metal nanomaterials include:
[0068] SiW12 (100 μmol) was dissolved in 55 mL of water in an ice bath (~3℃), and then K2PtCl6 (51.11 mg, containing 105 μmol of Pt) was added. After stirring the solution for 60 min, freshly prepared 0.03 M NaBH4 (5 mL, 150 μmol) ice-water solution was added dropwise over 10 min. Immediately after adding NaBH4, high specific surface area conductive support carbon nanotubes (CNTs) (100 mg) were added. The mixture was stirred for 20 min, and solid-liquid separation was performed to obtain the crude catalyst.
[0069] The crude catalyst was dispersed in water and stirred for 10 minutes. Then it was filtered and washed with water to obtain the target material. The obtained material was dried under vacuum (60°C) to obtain the supported catalyst, denoted as Pt NPs@SiW12 / CNT.
[0070] Example 3
[0071] The preparation steps of supported catalysts made from polyoxometalate-modified metal nanomaterials include:
[0072] SiW11 (100 μmol) was dissolved in 55 mL of water in an ice bath (~3℃), and then K2PtCl6 (51.11 mg, containing 105 μmol of Pt) was added. After stirring the solution for 60 min, freshly prepared 0.03 M NaBH4 (5 mL, 150 μmol) ice-water solution was added dropwise over 10 min. Immediately after adding NaBH4, high specific surface area conductive support carbon nanotubes (CNT) (100 mg) were added. The mixture was stirred for 20 min, and solid-liquid separation was performed to obtain the crude catalyst.
[0073] The crude catalyst was dispersed in water and stirred for 10 minutes. Then it was filtered and washed with water to obtain the target material. The obtained material was dried under vacuum (60°C) to obtain the supported catalyst, denoted as Pt NPs@SiW11 / CNT.
[0074] Example 4
[0075] The preparation steps of supported catalysts made from polyoxometalate-modified metal nanomaterials include:
[0076] SiW9 (100 μmol) was dissolved in 55 mL of water in an ice bath (~3℃), and then K2PtCl6 (51.11 mg, containing 105 μmol of Pt) was added. After stirring the solution for 60 min, freshly prepared 0.03 M NaBH4 (5 mL, 150 μmol) ice-water solution was added dropwise over 10 min. Immediately after adding NaBH4, high specific surface area conductive support carbon nanotubes (CNT) (100 mg) were added. The mixture was stirred for 20 min, and solid-liquid separation was performed to obtain the crude catalyst.
[0077] The crude catalyst was dispersed in water and stirred for 10 minutes. Then it was filtered and washed with water to obtain the target material. The obtained material was dried under vacuum (60℃) to obtain the supported catalyst, denoted as Pt NPs@SiW9 / CNT.
[0078] Figure 4 The infrared spectra of Pt NPs@SiW9, Pt NPs@SiW10, Pt NPs@SiW11, and Pt NPs@SiW12 are shown. Pt NPs@SiW9, Pt NPs@SiW10, Pt NPs@SiW11, and Pt NPs@SiW12 are the Pt NPs@SiW9, Pt NPs@SiW10, Pt NPs@SiW11, and Pt NPs@SiW12 loaded onto the support prepared in Examples 1-4.
[0079] Comparative Example
[0080] The preparation steps of the supported catalyst made of platinum nanomaterials include:
[0081] K2PtCl6 (51.11 mg, containing 105 μmol Pt) was mixed with 55 mL of ice bath (~3℃) water. After stirring the solution for 60 min, freshly prepared 0.03 M NaBH4 (5 mL, 150 μmol) ice water solution was added dropwise over 10 min. Immediately after adding NaBH4, high specific surface area conductive support carbon nanotubes (CNTs) (100 mg) were added. The mixture was stirred for 20 min, and solid-liquid separation was performed to obtain the crude catalyst.
[0082] The crude catalyst was dispersed in water (50 mL), stirred for 10 min, then filtered, and washed with 50 mL of water to obtain the target material. The obtained material was then vacuum dried (60 °C) to obtain the supported catalyst, denoted as Pt NPs / CNT.
[0083] Test case
[0084] Weigh 5 mg of catalyst powder, add water (100 μL), isopropanol (800 μL) and Nafion membrane solution (100 μL), sonicate to form a uniform dispersion, and then coat it onto a glassy carbon electrode.
[0085] The above dispersion was coated onto a glassy carbon electrode at a coating density of 150 μL / cm². 2 After drying, the working electrode is obtained.
[0086] The electrocatalytic oxygen reduction performance of the above working electrode was characterized by the following tests:
[0087] Electrochemical tests were performed using a Shanghai Chenhua electrochemical workstation (CHI770E) in a three-electrode system with a reversible hydrogen electrode as the reference electrode, a platinum wire as the counter electrode, the electrode prepared above as the working electrode, and 0.5 mol / L H2SO4 solution as the electrolyte solution.
[0088] Figure 5 Linear sweep voltammetry (LSV) curves for electrocatalytic oxygen reduction using different electrodes are shown in the figure. In the figure, 20% Pt / C represents a commercially available platinum-carbon modified glassy carbon electrode; PtNPs / CNT represents the glassy carbon electrode modified with the material from Comparative Example 1; PtNPs@SiW10 / CNT represents the glassy carbon electrode modified with the material from Example 1; PtNPs@SiW12 / CNT represents the glassy carbon electrode modified with the material from Example 2; PtNPs@SiW11 / CNT represents the glassy carbon electrode modified with the material from Example 3; and PtNPs@SiW9 / CNT represents the glassy carbon electrode modified with the material from Example 4.
[0089] As can be seen from the figure, PtNPs@SiW 10 The half-wave potential of / CNT at 0.835V vs. RHE and the limiting diffusion current density at 6.93mA cm⁻² are both superior to those of commercial platinum carbon.
[0090] Figure 6 For PtNPs@SiW 10 Stability curves of electrodes modified with PtNPs / CNT, Pt NPs / CNT, and commercial platinum carbon during electrocatalytic oxygen reduction. As shown in the figure, after 10,000 cyclic voltammetric accelerated aging tests, its performance degradation was only 28 mV, demonstrating excellent stability, far exceeding that of PtNPs / CNT catalysts and commercial platinum carbon.
[0091] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0092] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A supported electrocatalyst for platinum nanomaterials modified with polyacid ligands, characterized in that, The supported electrocatalyst includes a multi-walled carbon nanotube conductive support with a high specific surface area, and platinum nanomaterials modified with polyacid ligands supported on the conductive support.
2. The supported electrocatalyst as described in claim 1, characterized in that, The polyacid ligand includes silicotungstic acid [α-SiW9O] 34 ] 10- (abbreviation: SiW9), [γ-SiW 10 O 36 ] 8- (abbreviation: SiW10), [β2-SiW 11 O 39 ] 8- (Abbreviation: SiW11), [SiW 12 O 40 ] 4- (Abbreviation: SiW12).
3. A method for preparing a supported electrocatalyst as described in claim 1 or 2, characterized in that the step... include: The polyacid ligands were dissolved in water at 0-5℃ to obtain a ligand solution; A platinum nanomaterial precursor was added to the ligand solution and stirred to obtain a mixed solution. Sodium borohydride (NaBH4) solution was added dropwise to the mixed solution, followed by the addition of a multi-walled carbon nanotube conductive support. The resulting solid product was purified and dried to obtain the supported electrocatalyst. The concentration of the sodium borohydride (NaBH4) solution is 0.01–0.05 M.
4. The preparation method according to claim 3, characterized in that, The concentration of the polyacid ligand in the ligand solution is 1–4 mM; and / or the molar ratio of the polyacid ligand to the platinum nanomaterial precursor is 0.3–4.
5. The preparation method according to claim 3, characterized in that, The molar ratio of the platinum nanomaterial precursor to the reducing agent in the sodium borohydride (NaBH4) solution is 0.02–0.3; and / or, the platinum nanomaterial precursor is K2PtCl6.
6. The preparation method according to claim 3, characterized in that, The purification steps include: dispersing the solid product in water, stirring and filtering, and then washing with water 2 to 3 times; and / or, the drying is vacuum drying.
7. An electrode for oxygen reduction at the cathode of a fuel cell, characterized in that, The active component of the electrode includes the supported electrocatalyst of platinum nanomaterials modified with polyacid ligands as described in claim 1 or 2.
8. A method for oxygen reduction at the cathode of a fuel cell, characterized in that, The method uses the electrode described in claim 7 as the working electrode.