Modified platinum-based oxygen reduction catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of fuel cell electrode materials, and particularly relates to a modified platinum-based oxygen reduction catalyst and a preparation method and application thereof. The modified platinum-based oxygen reduction catalyst comprises a platinum-based catalyst, and the surface of the platinum-based catalyst is covered with a modifier containing halogen elements or nitrogen. The modified platinum-based oxygen reduction catalyst has remarkably improved oxygen reduction electro-catalysis performance. Furthermore, the invention also provides application of the modified platinum-based oxygen reduction catalyst as a fuel cell cathode material. The invention provides a new thought and strategy for the design of the oxygen reduction catalyst of the fuel cell, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell electrode material technology, specifically relating to a modified platinum-based oxygen reduction catalyst, its preparation method, and its applications. Background Technology

[0002] An ion-exchange membrane fuel cell (IEMFC) is a device that uses an ion-exchange membrane as the electrolyte to directly convert the chemical energy of fuel (such as hydrogen, methanol, ammonia, etc.) and oxidant (usually oxygen) into electrical energy through an electrochemical reaction. Its core feature is the use of an ion-exchange membrane (cation exchange membrane or anion exchange membrane) to conduct specific ions (such as H+). + OH - (etc.), while isolating fuel and oxidizer to achieve efficient and clean energy conversion.

[0003] One of the key technical challenges hindering the development of IEMFCs lies in the high overpotential of cathode ORR, with even the most active platinum-based catalysts exhibiting onset overpotentials exceeding 200 mV. Therefore, improving the activity of the cathode ORR reaction is a crucial scientific issue in this field. Research on enhancing ORR activity on platinum has primarily focused on the electrode. Modulation of electrode surface composition and structure has become an effective strategy. Specific improvement strategies mainly include:

[0004] (1) Alloying is widely considered a promising approach. Platinum-based nanoparticles, which are commonly used as ORR catalysts, can be further enhanced by alloying with other transition metals. In various studies, the Pt3Ni(111) structure has been identified as the most active due to its platinum outer shell structure and the coordination effect of Ni in the sublayer.

[0005] (2) In addition, core-shell nanocatalysts with inexpensive transition metal cores also showed improved ORR activity, mainly attributed to strain effects.

[0006] (3) Furthermore, modifying the electrode surface by introducing specific adsorbent species, such as cyanide, melamine and sulfide, has been shown to be effective in improving ORR performance.

[0007] In existing studies, the mechanisms underlying the enhancement of ORR by adsorbed species have been attributed to electronic effects, geometric effects, or a synergistic combination of both. However, the effects of different adsorbed species on electrode ORR activity are highly diverse, and the number of adsorbed species found to improve ORR performance is very limited. More often, the chemisorption of anions from the solution phase (such as halide ions, sulfates, nitrates, and (bis)phosphates) leads to poisoning effects and reduces ORR activity (Journal of Energy Chemistry 94. 2024. 70–77).

[0008] Even the presence of water can pose serious problems. Heterocatalysis typically must be carried out in dry environments because exposure to humidity can deactivate the catalyst. The situation is even more challenging in electrocatalysis. Due to its high polarity, water can interact significantly with active sites in charged interfacial environments. However, water is often the solvent of choice in electrochemistry and participates directly in relevant reactions as either a product or a reactant. For ORR, theoretical analysis suggests that water adsorption reduces ORR activity. But because it is ubiquitous in electrochemical cells, it is difficult to devise strategies to control it, and even experimentally, it is difficult to measure.

[0009] Therefore, developing new platinum-based ORR electrode materials modified with adsorbent species is an important research topic in this field. It can provide new research and development ideas and strategies for the development of ORR electrode materials and has high application value. Summary of the Invention

[0010] To address the problems of existing technologies, this invention provides a modified platinum-based oxygen reduction catalyst, its preparation method, and its applications.

[0011] A modified platinum-based oxygen reduction catalyst includes a platinum-based catalyst, the surface of which is coated with a halogen-containing or nitrogen-containing modifier.

[0012] The nitrogen-containing modifier is a compound of formula I or II or a salt thereof:

[0013]

[0014] Among them, R1 and R2 are independently selected from C1-C 10 Alkyl groups;

[0015] R3 is selected from C1-C 10 Alkyl groups;

[0016] R4 is selected from H, C1-C 10 Alkyl, C1-C 10 The amino group;

[0017] Alternatively, R3 and R4 may be linked to form a substituted or unsubstituted 5-10 membered nitrogen-containing heterocycle, wherein the substituents are selected from C1-C2. 10 Alkyl groups;

[0018] R5 is selected from H, hydroxyl group, oxygen free radical, C1-C. 10 Alkyl groups;

[0019] Ring A is selected from substituted or unsubstituted 6-10 member nitrogen-containing heteroaryl groups, wherein the substituents are selected from C1-C2. 10 Alkyl groups;

[0020] R6 and R7 are independently selected from C1-C1. 10 Alkyl groups.

[0021] Preferably, the halogen-containing modifier is selected from one or a combination of at least two of halogen atoms, halide anions, halogen-containing molecules, or halogen-containing anions; the halogen atom is selected from one or a combination of at least two of Cl, Br, or I; and the halide anion is selected from Cl... - ,Br - Or I - One or at least two of them.

[0022] Preferably, the coverage of the halogen-containing modifier is less than or equal to 0.95 mL.

[0023] Preferably, the halogen-containing modifier is selected from I or I - The halogen-containing modifier has a coverage of less than or equal to 0.5 mL, and is in combination with one or at least two of the halogen-containing elements.

[0024] Alternatively, the halogen-containing modifier is selected from Cl, Cl - Br or Br - The halogen-containing modifier has a coverage of less than or equal to 0.95 mL, and is a combination of one or at least two of the halogen-containing modifiers.

[0025] Preferably, the platinum-based catalyst is selected from one or a combination of at least two of the following materials: non-micro / nano-scale Pt single crystal materials, non-micro / nano-scale Pt polycrystalline materials, single crystal Pt micron materials, polycrystalline Pt micron materials, single crystal Pt nanoparticles, and polycrystalline Pt nanoparticles.

[0026] Preferably, the platinum-based catalyst is composed of elemental Pt or a Pt-containing alloy material; the Pt-containing alloy material is selected from one or a combination of at least two of the following alloys: PtNi alloy, PtCo alloy, PtFe alloy, or PtCu alloy.

[0027] Preferably, the Pt-containing alloy material is selected from PtCo alloys, and the modifier is selected from I or I- The halogen-containing modifier has a coverage of less than or equal to 0.12 mL, and is a combination of one or at least two of the halogen-containing modifiers.

[0028] Preferably, the crystal orientation of the platinum-based catalyst surface includes one or a combination of at least two of the following crystal planes: Pt(111) and Pt(332).

[0029] Preferably, the crystal orientation of the platinum-based catalyst surface includes Pt(111), and the halogen-containing modifier is selected from I or I - The halogen-containing modifier has a coverage of less than or equal to 0.37 mL, consisting of one or at least two of the halogen-containing elements.

[0030] Alternatively, the crystal orientation of the platinum-based catalyst surface may include Pt(332), and the halogen-containing modifier may be selected from I or I - The halogen-containing modifier has a coverage of less than or equal to 0.28 mL, consisting of one or at least two of the halogen-containing elements.

[0031] Alternatively, the crystal orientation of the platinum-based catalyst surface may include Pt(111), and the halogen-containing modifier may be selected from Br or Br₂. - The halogen-containing modifier has a coverage of less than or equal to 0.6 mL, and is a combination of one or at least two of the halogen-containing modifiers.

[0032] Preferably, the crystal orientation of the platinum-based catalyst surface includes Pt(111), and the halogen-containing modifier is selected from I or I - The halogen-containing modifier has a coverage of 0.16-0.34 mL, comprising one or at least two of the following:

[0033] Alternatively, the crystal orientation of the platinum-based catalyst surface may include Pt(332), and the halogen-containing modifier may be selected from I or I - The halogen-containing modifier has a coverage of 0.23-0.28 mL, consisting of one or at least two of the halogen-containing elements.

[0034] Alternatively, the crystal orientation of the platinum-based catalyst surface may include Pt(111), and the halogen-containing modifier may be selected from Br or Br₂. - The halogen-containing modifier has a coverage of 0.42-0.6 mL, consisting of one or at least two of the halogen-containing elements.

[0035] Preferably, the modified platinum-based oxygen reduction catalyst is prepared by immersing the platinum-based catalyst in an aqueous solution containing halides or halogen elements, controlling the coverage of halogen anions or halogen atoms by immersion time, and then cleaning the platinum-based catalyst to obtain the catalyst.

[0036] Alternatively, the modified platinum-based oxygen reduction catalyst can be prepared by immersing the platinum-based catalyst in a solution of a nitrogen-containing modifier, controlling the coverage of the nitrogen-containing modifier by the immersion time, and then washing the platinum-based catalyst to obtain the catalyst.

[0037] Preferably, the aqueous solution is an I2 solution with a concentration of less than or equal to 1.0 mM and a soaking time of less than or equal to 30 s;

[0038] Alternatively, the aqueous solution contains I - The solution containing I - The solution concentration is less than or equal to 1.0 mM, and the soaking time is less than or equal to 120 s.

[0039] Preferably, the modified platinum-based oxygen reduction catalyst is prepared by spin-coating an aqueous solution containing a halide or halogen element onto the surface of the platinum-based catalyst, controlling the coverage of halogen anions or halogen atoms by the amount of spin-coating, and evaporating the solution to obtain the catalyst.

[0040] Alternatively, the modified platinum-based oxygen reduction catalyst can be prepared by spin-coating a solution of a nitrogen-containing modifier onto the surface of the platinum-based catalyst, controlling the coverage of the nitrogen-containing modifier by the amount of spin-coating, and then evaporating the solution to obtain the catalyst.

[0041] Preferably, R1 and R2 are selected from methyl groups;

[0042] R3 is selected from methyl;

[0043] R4 is selected from H, C1-C4 alkyl, and C6 amino groups;

[0044] Alternatively, R3 and R4 may be linked to form a substituted or unsubstituted 6-membered nitrogen-containing heterocycle, wherein the substituent is selected from methyl groups;

[0045] R5 is selected from H, hydroxyl, oxygen free radical, and methyl;

[0046] Ring A is selected from a 6-membered nitrogen-containing heteroaryl group;

[0047] R6 and R7 are selected from methyl groups.

[0048] Preferably, the structure of the compound shown in Formula I is as shown in Formula III or Formula IV:

[0049]

[0050]

[0051] Where n is selected from 1 or 2.

[0052] Preferably, the nitrogen-containing modifier is selected from:

[0053]

[0054] Preferably, the coverage of the nitrogen-containing modifier is less than or equal to 0.6 mL.

[0055] The present invention also provides a method for preparing the above-mentioned modified platinum-based oxygen reduction catalyst, comprising the following steps: immersing the platinum-based catalyst in an aqueous solution containing halides or halogen elements, controlling the coverage of halogen anions or halogen atoms by immersion time, and cleaning the platinum-based catalyst to obtain the catalyst.

[0056] Alternatively, the platinum-based catalyst can be immersed in a solution of a nitrogen-containing modifier, and the coverage of the nitrogen-containing modifier can be controlled by the immersion time. The platinum-based catalyst can then be washed to obtain the final product.

[0057] The present invention also provides a method for preparing the above-mentioned modified platinum-based oxygen reduction catalyst, comprising the following steps: the method for preparing the modified platinum-based oxygen reduction catalyst is as follows: spin-coating an aqueous solution containing a halide or halogen element onto the surface of the platinum-based catalyst, controlling the coverage of halogen anions or halogen atoms by the amount of spin-coating, and evaporating the solution to obtain the catalyst.

[0058] Alternatively, a solution of a nitrogen-containing modifier can be spin-coated onto the surface of the platinum-based catalyst, and the coverage of the nitrogen-containing modifier can be controlled by the amount of spin-coating. The solution can then be evaporated to obtain the final product.

[0059] The present invention also provides the use of the above-described modified platinum-based oxygen reduction catalyst in the preparation of or as an oxygen reduction electrocatalyst.

[0060] The present invention also provides a fuel cell, wherein the fuel cell uses the above-mentioned modified platinum-based oxygen reduction catalyst as the cathode electrocatalyst.

[0061] In this invention, the term "coverage" refers to the ratio of the number of electrode surface modifiers (atoms, molecules, or ions) to the number of platinum atoms.

[0062] The compounds and derivatives provided in this invention can be named according to the IUPAC (International Union of Pure and Applied Chemistry) or CAS (Chemical Abstracts Service, Columbus, OH) nomenclature system.

[0063] Regarding the definition of terms used in this invention: Unless otherwise stated, the initial definitions provided for groups or terms herein apply to the groups or terms used throughout this specification; for terms not specifically defined herein, the meanings that a person skilled in the art would give them should be given based on the disclosure and context.

[0064] "Substitution" refers to the replacement of hydrogen atoms in a molecule by other different atoms or molecules.

[0065] The minimum and maximum carbon atom content in hydrocarbon groups are indicated by a prefix, for example, the prefix C. a -C bAlkyl indicates any alkyl group containing "a" to "b" carbon atoms. Therefore, for example, "C1-C4 alkyl" refers to alkyl groups containing 1 to 4 carbon atoms.

[0066] "Alkyl" refers to a saturated hydrocarbon chain having a specified number of member atoms. For example, C1-C6 alkyl refers to an alkyl group having 1 to 6 member atoms, such as 1 to 4 member atoms. Alkyl groups can be straight-chain or branched. Representative branched alkyl groups have one, two, or three branches. Alkyl groups may optionally be substituted by one or more substituents as defined herein. Alkyl groups include methyl, ethyl, propyl (n-propyl and isopropyl), butyl (n-butyl, isobutyl, and tert-butyl), pentyl (n-pentyl, isopentyl, and neopentyl), and hexyl.

[0067] "Halogen" refers to fluorine, chlorine, bromine, or iodine.

[0068] "Heterocyclic" or "heterocyclic alkyl" refers to a saturated ring or a non-aromatic unsaturated ring containing at least one heteroatom; where the heteroatom refers to a nitrogen atom, an oxygen atom, or a sulfur atom.

[0069] "Aromatic heterocycle" refers to an aromatic unsaturated ring containing at least one heteroatom; where the heteroatom refers to a nitrogen atom, an oxygen atom, or a sulfur atom.

[0070] When two substituents are "linked together to form a ring," it means that at least one atom in each of the two substituents is connected by a chemical bond, so that a part of the molecular skeleton to which the two substituents are linked together forms a ring structure together with the two substituents.

[0071] Given the prevailing belief in the art that halogens poison the ORR performance of Pt-based electrodes, this invention is the first to discover a halogen-containing modifier that can modify the surface of Pt-based electrodes into a sub-monolayer, thereby modifying the electrode material and significantly improving its ORR performance. Using this modification method, under optimal process conditions, the modified platinum-based oxygen reduction catalyst obtained in this invention exhibits ORR activity even superior to the best reported Pt-based ORR catalyst to date, Pt3Ni(111).

[0072] On the other hand, this invention also discovers for the first time that modifying the surface of a Pt-based electrode with sub-monolayer amine compounds or nitrogen-containing heterocyclic compounds (nitrogen-containing modifiers) can also improve the ORR performance of the Pt-based electrode. The nitrogen-containing modifiers with the promoting effect have the following structural characteristics: 1) nitrogen acts as a proton anchor; 2) the α-C has no α-H, ensuring stable adsorption; 3) the α-C is connected to at least one alkyl group (such as methyl) to provide a hydrophobic environment; 4) the substituents connected to nitrogen do not contain benzene rings or conjugated structures.

[0073] Therefore, this invention provides new ideas and strategies for the design of oxygen reduction catalysts for fuel cells, and has great application prospects.

[0074] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0075] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0076] Figure 1 (a) Cyclic voltammogram of Pt(111) electrode and (b) forward scan of oxygen reduction reaction (jE) curve in 0.1M HClO4 + 0.1mM KX (X=Cl,Br,I). For comparison, (a) and (b) also include cyclic voltammogram and jE curve of oxygen reduction reaction for unmodified Pt(111). Scan rate: 50mV / s. Electrode rotation rate was 1600 rpm in the oxygen reduction reaction experiment.

[0077] Figure 2 Cyclic voltammograms and jE curves of the oxygen reduction reaction for (a,b) I2-modified Pt(111)@x ML I* electrodes. Cyclic voltammograms and jE curves of the oxygen reduction reaction for (c,d) KI-modified Pt(111)@x ML I* electrodes. Insets: Detailed views of the kinetic regions of the oxygen reduction reaction polarization curves and the shift in the oxygen reduction reaction onset potential. For comparison, cyclic voltammograms and jE curves of the oxygen reduction reaction for unmodified Pt(111) are also included in (a,c) and (b,d). Scan rate: 50 mV / s. The rotation rate was 1600 rpm in the oxygen reduction reaction experiments.

[0078] Figure 3 (a) Cyclic voltammogram of the Pt(322)@x ML I* electrode in Ar-saturated 0.1M HClO4. (b) Oxygen reduction reaction polarization curve of the Pt(322)@x ML I* electrode in O2-saturated 0.1M HClO4, scanned in the forward direction. Inset: Detailed view of the kinetic region of the oxygen reduction reaction polarization curve and the shift of the oxygen reduction reaction half-wave potential. For comparison, the baseline cyclic voltammogram of unmodified Pt(322) and the jE curve of the oxygen reduction reaction are also included in the figure. Scan rate: 50 mV / s. The rotation rate was 1600 rpm in the oxygen reduction reaction experiment.

[0079] Figure 4 Cyclic voltammograms and oxygen reduction reaction (ORR) activities of PtCo alloy nanoparticle catalysts modified with sub-monolayer I are shown. (a) Cyclic voltammogram of the PtCo@x ML I* electrode in Ar-saturated 0.1M HClO4. (b) Polarization curve of the OR reaction of the PtCo@x ML I* electrode in O2-saturated 0.1M HClO4, scanned in the forward direction. For comparison, cyclic voltammograms and the JE curve of the OR reaction of unmodified PtCo are also included in (a) and (b). Scan rate: 50 mV / s. The rotation rate in the OR reaction experiment was 1600 rpm.

[0080] Figure 5 trace amounts of Cl - The effect of Pt(111) on the oxygen reduction reaction performance in 0.05M H2SO4 (a,b), 0.05M H3PO4 (c,d), and 0.10M HClO4 (e,f). (a,b) shows the CVs and oxygen reduction reaction polarization curves of Pt(111) in 0.05M H2SO4 and 0.05M H2SO4 + x mM KCl solutions, with a pH of 1.25. (c,d) shows the CVs and oxygen reduction reaction polarization curves of Pt(111) in 0.05M H3PO4 and 0.05M H3PO4 + 10mM KCl solutions, with a pH of 1.76. (e,f) shows the CVs and oxygen reduction reaction polarization curves of Pt(111) in 0.10M HClO4 and 0.10M HClO4 + 0.020mM KCl solutions, with a pH of 1.01. Electrode rotation speed for CVs testing: 0 rpm; scan rate: 50 mV / s. Electrode rotation speed for oxygen reduction reaction polarization curve testing: 3600 rpm; scan rate: 100 mV / s.

[0081] Figure 6 For trace amounts of Br ‒ The effect of Pt(111) on the oxygen reduction reaction performance in 0.05 M H2SO4, 0.05 M H3PO4 and 0.10 M HClO4 was investigated. (a, b) show the cyclic voltammograms (CVs) of Pt(111) in 0.05 M H2SO4 and 0.05 M H2SO4 + 5 μM KBr solutions at pH 1.25; (c, d) show the CVs and oxygen reduction reaction polarization curves in 0.05 M H3PO4 + x μM KBr (x = 0, 5 μM) solution at pH 1.76; (e, f) show the CVs and oxygen reduction reaction polarization curves in 0.10 M HClO4 + x μM KBr (x = 0, 5 μM) solution at pH 1.01.

[0082] Figure 7 Cyclic voltammograms and oxygen reduction reaction (ORR) activity of Pt(111)@x ML Br* are shown. (a) Cyclic voltammograms of Pt(111) electrodes modified with Br at different coverage levels. (b) Polarization curves of ORR recorded at the Pt(111)@x ML Br* / 0.1M HClO4 interface under a positive scan. Inset: Polarization curves of ORR under a negative scan. For comparison, cyclic voltammograms and JE curves of the ORR of unmodified Pt(111) are also included. The scan rate was 50 mV / s. The electrode rotation rate was 1600 rpm in the ORR experiment.

[0083] Figure 8 (a) Cyclic voltammograms (upper part) and ORR jE curves (lower part) of Pt(111) electrode in 0.1M NaOH electrolyte solution and 3μM NaI+0.1M NaOH electrolyte solution, respectively; (b) Cyclic voltammograms (upper part) and ORR jE curves (lower part) of Pt polycrystalline electrode in 0.1M NaOH electrolyte solution and 3μM NaI+0.1M NaOH electrolyte solution, respectively; (c) Cyclic voltammograms (upper part) and ORR jE curves (lower part) of Pt nanoelectrode in 0.1M NaOH electrolyte solution and 0.01mM NaI+0.1M NaOH electrolyte solution, respectively.

[0084] Figure 9 (a) Chemical structures, abbreviations, and pKa values ​​of different types of nitrogen-containing modifiers; (b, c, d) Cyclic voltammetry plots of Pt(111) electrodes modified with different nitrogen-containing modifiers in argon-saturated 0.1M HClO4 solution; (e, f, g) Oxygen reduction reaction (ORR) polarization curves of the modified Pt(111) electrode recorded during the forward scan in oxygen-saturated 0.1M HClO4 solution, with the shift of the ORR half-wave potential marked in the figure. For comparison, the basic CV curve of the unmodified Pt(111) electrode and the jE curve of ORR are also included in (b, c, d) and (e, f, g), respectively. The scan rate was 50 mV / s; the rotation rate of the ORR experiment was 1600 rpm.

[0085] Figure 10(a, d) show the chemical structures, abbreviations, and pKa values ​​of different types of amine molecules; (b, e) show the cyclic voltammograms of Pt(111) electrodes modified with different types of amine molecules in argon-saturated 0.1M HClO4 solution; (c, f) show the oxygen reduction reaction (ORR) polarization curves recorded by the modified Pt(111) electrode during the forward scan in oxygen-saturated 0.1M HClO4 solution. For ease of comparison, the basic CV curve and the jE curve of ORR for the bare Pt(111) electrode are also shown in the figure. Scan rate: 50 mV / s; rotation rate of ORR experiment: 1600 rpm.

[0086] Figure 11 (a, c, e) Cyclic voltammetry (CV) curves of t-BuNH2-modified Pt(111), polycrystalline Pt electrode, and Pt nanoparticles in 0.1 M NaOH solution containing 0.05 mM t-BuNH2. (b, d, f) Oxygen reduction reaction (ORR) polarization curves of Pt(111), polycrystalline Pt electrode, and Pt nanoparticles recorded during the forward scan, with the shift of the ORR onset potential marked. For comparison, the basic CV curves of bare Pt(111) and bare polycrystalline Pt electrode, as well as their ORR jE curves, are also shown in the figure. Scan rate: 50 mV / s; Electrode rotation rate for ORR experiments: 1600 rpm. Detailed Implementation

[0087] In the following examples and experimental cases, reagents and raw materials not specifically described are all commercially available products.

[0088] Example 1: Surface-modified I-submonolayer Pt electrode

[0089] This embodiment provides a Pt electrode with a surface modified with a sub-monolayer (I). The Pt electrode can be a polycrystalline Pt electrode, a single-crystal Pt electrode, or Pt-based nanoparticles. The Pt-based nanoparticles provided in this embodiment are PtCo alloy nanoparticle catalysts, purchased from Tanaka Corporation, trade number TEC36E52. The surface of the single-crystal Pt electrode can be selected from Pt(111), Pt(332), or other crystal planes. The preparation method of the single-crystal Pt electrode can be implemented according to existing techniques (e.g., the Calliver method).

[0090] The method for modifying a sub-monolayer of I on the surface of a Pt electrode is as follows:

[0091] Step 1, for polycrystalline Pt electrodes and Pt-based nanoparticles, can be directly modified; for single-crystal Pt electrodes, annealing is required before modification, as detailed below:

[0092] A single-crystal Pt electrode, such as a Pt(111) electrode, is annealed for 100 seconds by induction heating at 400 A (the current can be adjusted according to the diameter of the Pt electrode), then completely cooled in a reducing atmosphere of Ar / CO(9:1) and transferred to ultrapure water saturated with an Ar / CO mixture.

[0093] Step 2: Immerse the Pt electrode in an aqueous solution containing KI (0.01 mM-1 mM) or I2 (0.01 mM-1 mM), with the coverage controlled by the immersion time. After cleaning, subsequent electrochemical experiments can be performed.

[0094] Step 3: The I-modified Pt electrode obtained in Step 2 is subjected to cyclic voltammetry (CV) in 0.1M HClO4. The electrochemical active area of ​​the electrode can be calculated by integrating the hydrogen region (see Experimental Example 1 for the specific principle). By utilizing the change in the electrochemical active area of ​​the Pt electrode before and after modification, the coverage of I atoms on the prepared modified Pt electrode can be calculated.

[0095] Through experiments, this embodiment prepared various I-modified Pt electrodes with different coverage using the process conditions shown in the table below:

[0096]

[0097] Note: In the table above, the naming rule for each sample is: "Platinum electrode type@coverage I*", for example, "Pt(111)@0.06ML I*" means that 0.06ML of I is modified on the surface of Pt(111) electrode.

[0098] Example 2: Pt electrode with Cl and Br sub-monolayer modified surface

[0099] This embodiment provides a Pt electrode with a surface-modified Cl and Br sub-monolayer. The electrode preparation method of this embodiment is as follows: a specific volume of KCl or KBr solution is spin-coated onto the surface of the Pt electrode and the solution is evaporated.

[0100] In this embodiment, various Br-modified Pt electrodes with different coverage (hereinafter referred to as Pt(111)-Br*) were prepared using the process conditions shown in the table below:

[0101]

[0102] Furthermore, since the adsorption capacity of Cl and Br is weaker than that of I, this embodiment can also use the following method to prepare a Pt electrode with a surface modified Cl and Br sub-monolayer:

[0103] By placing an unmodified Pt electrode in a solution containing trace amounts of Cl - (or Br) -Electrochemical reactions (such as CV scanning or ORR reaction) are carried out in the electrolyte solution to generate a Pt electrode with a surface-modified Cl and Br sub-monolayer.

[0104] For example, the composition of an electrolyte solution can be:

[0105] 1. 0.05M H2SO4 + x mM KCl (or KBr);

[0106] 2. 0.05M H3PO4 + x mM KCl (or KBr);

[0107] 3. 0.10M HClO4 + x mM KCl (or KBr).

[0108] Where x takes values ​​ranging from 0.005 to 20.

[0109] Furthermore, under alkaline conditions, Pt electrodes with Cl, Br, and I sub-monolayers on their surfaces can all be prepared using the following methods:

[0110] By placing an unmodified Pt electrode into a container containing trace amounts of I - (or Cl) - ,Br - Electrochemical reactions (such as CV scanning or ORR reaction) are carried out in the electrolyte solution to generate a Pt electrode with a surface-modified Cl, Br, I sub-monolayer.

[0111] For example, the composition of an electrolyte solution can be:

[0112] 0.1M NaOH + xμM NaI (or NaCl, NaBr);

[0113] 0.1M KOH + xμM KI (or KCl, KBr);

[0114] Where x takes values ​​ranging from 3 to 10.

[0115] Example 3: Pt electrode with surface-modified sub-monolayer nitrogen-containing modifier

[0116] This embodiment provides a Pt electrode with a surface-modified sub-monolayer nitrogen-containing modifier. The electrode preparation method of this embodiment is as follows:

[0117] Pt(111) single-crystal electrodes were prepared using the Clavilier method. Various nitrogen-containing modifier molecules were dissolved in ethanol to prepare 5 mM solutions. After cleaning with 0.1 M HClO4, the Pt(111) electrode was washed with water and then immersed in the aforementioned nitrogen-containing modifier solutions for 1-3 minutes (3 minutes in this example) to form a saturated, irreversible adsorption layer. The electrode was then washed with water. Coverage was calculated using the HUPD charge.

[0118] The nitrogen-containing modifiers used in this embodiment include the following.

[0119]

[0120] Through H UPD The saturation coverage of various nitrogen-containing modifiers calculated by charge is shown in the table below:

[0121]

[0122]

[0123] Example 4: Fuel Cell with Modified Platinum-Based Oxygen Reduction Catalyst

[0124] The basic components and structure of the fuel cell in this embodiment can be implemented using existing technologies. Specifically, it mainly includes: a cathode assembly, an anode assembly, an electrolyte membrane, a gas diffusion layer, and a housing. The electrocatalyst material in the cathode assembly is a Pt electrode with a surface-modified I sub-monolayer prepared in Example 1, or a Pt electrode with a surface-modified Cl or Br sub-monolayer prepared in Example 2, or a Pt electrode with a surface-modified nitrogen-containing sub-monolayer prepared in Example 3. The anode assembly, electrolyte membrane, gas diffusion layer, and housing can be implemented based on existing technologies.

[0125] The technical solution of the present invention will be further explained below through experimental data.

[0126] In the following experimental examples, the electrode potentials were controlled by a potentiometer (Autolab 302N). All experimental methods for cyclic voltammetry (CV) and oxygen reduction reaction (ORR) on the electrodes are prior art. The modified electrode samples used were prepared according to the methods of Example 1, Example 2, or Example 3. Unless otherwise specified, the Pt(111)@I* samples used in the following experiments were prepared by soaking Pt(111) electrodes in KI solution.

[0127] Experimental Example 1: Poisoning Effect of Halogens in Electrolytes on the Oxygen Reduction Kinetics of the Pt(111) Electrode

[0128] I. Experimental Methods

[0129] CV detection and ORR testing of the unmodified Pt(111) electrode were performed in 0.1M HClO4 solution and 0.1M HClO4+0.1mM KX (X=Cl、Br、I) solution, respectively.

[0130] II. Experimental Results

[0131] Figure 1Cyclic voltammetry (CVs) and ORR polarization curves are shown for the addition of 0.1 mM KX (X = Cl, Br, I) to 0.1 M perchloric acid (HClO4) solution. Even with the addition of only 0.1 mM KX, the ORR current-potential (jE) curve shifts significantly towards the negative potential. At the same concentration of KX, the inhibition of ORR on Pt(111) decreases in the order KI > KBr > KCl, consistent with previous studies.

[0132] The experimental results above show that the presence of 0.1 mM halide ions in the electrolyte HClO4 solution has a significant inhibitory effect on the ORR activity of the Pt electrode.

[0133] Experimental Example 2: ORR activity of a Pt electrode with a surface-modified I sub-monolayer

[0134] I. Experimental Methods

[0135] This experimental example investigated the ORR activity of a surface-modified I submonolayer Pt electrode prepared according to the method of Example 1 in 0.1M HClO4 electrolyte.

[0136] II. Experimental Results

[0137] 1. ORR activity of surface-modified I sub-monolayer Pt(111) electrode (Pt(111)@I*)

[0138] like Figure 2 As shown in a and 2b, when the Pt(111) surface is completely covered by iodine (at which point the iodine coverage θ) I At a concentration of 0.44 mL, there was almost no ORR activity at E > 0.6 V (see [reference]). Figure 1 This has also been reported in other literature. When θ I When the concentration was reduced to 0.41 mL, the partially covered Pt(111) initially exhibited activity for the 2-electron ORR, producing H₂O₂. Further reduction of θ... I At 0.31 mL, it showed activity for the 4-electron ORR process, and the current generated at this point was higher than that of the unmodified I Pt(111) electrode. Figure 2 (b and 2d).

[0139] The corresponding CV curves, such as Figure 2 As shown in a and 2c, it is roughly similar to clean Pt(111). The region of electrode potential E = 0.05 to 0.4 V is due to underpotential deposition of hydrogen (HUPD). The region of E = 0.6 to 1.0 V is due to hydroxyl (OH) groups. adAdsorption. Separating these two regions is a double-layer charging region at E = 0.4 to 0.6 V. Compared to the CV of clean Pt(111), the starting position of the HUPD region shifts to a lower E as I* coverage increases. The integrated charge density of HUPD decreases from the 0.4 V to 0.05 V potential region, which can provide an estimate of θ. I The method used is known to achieve a HUPD coverage of 2 / 3 ml at 0.05 V. Calculated values ​​are as follows: Figure 2 As shown in a and 2c. In OH ad Region, with θ I As the potential increases, the current peak formed by OH* shifts to higher potentials, and higher surface coverage is also indicated by a decrease in integrated charge density.

[0140] To further compare whether there is a difference in ORR activity between Pt(111)@xML I* samples prepared using I2 or KI, this experimental example further compares various θ values ​​obtained by the two preparation methods. I CVs and ORR polarization curves of the Pt(111)@x ML I* sample. Results are as follows... Figure 2 As shown in c and d, it can be seen that the Pt(111)@x ML I* samples obtained by both preparation methods exhibit consistent behavior in both the CVs curve and the ORR polarization curve. This indicates that regardless of whether I2 or KI is used as the precursor for I modification, the final form and properties of I atoms on the Pt electrode surface are the same or similar.

[0141] Further experiments revealed that when the iodine coverage was less than or equal to 0.37 mL (especially in the range of 0.16–0.34 mL), the Pt(111) electrode with surface-modified I submonolayer exhibited superior ORR activity compared to the unmodified electrode. Furthermore, for some of the best coverage levels (e.g., 0.31 mL), the Pt(111) electrode with surface-modified I submonolayer showed superior ORR activity compared to the best Pt-based ORR catalyst reported to date, Pt3Ni(111).

[0142] 2. Oxygen reduction activity of Pt(hkl) electrode (Pt(hkl)@I*) with surface-modified sub-monolayer I.

[0143] Figure 3 Cyclic voltammetry (CVs) and ORR polarization curves of the Pt(332)@I* electrode are shown. It can be seen that I modification on the Pt(332) electrode surface also enhances oxygen reduction activity. When θ I When the range is less than or equal to 0.28 mL (especially when it is in the range of 0.23-0.28 mL), it can enhance ORR activity.

[0144] 3. Oxygen reduction activity of PtCo alloy electrode with surface-modified sub-monolayer I (PtCo@I*)

[0145] Figure 4 The cyclic voltammetry (CVs) and ORR polarization curves of the PtCo alloy nanoparticle catalyst with I modification are shown. It can be clearly seen that when θ I When the range is less than or equal to 0.12 mL, I* enhances oxygen reduction activity, but when θ I When the range is greater than 0.12 mL, oxygen reduction activity is inhibited by I*.

[0146] Experimental Example 3: Trace Cl - Impact on ORR performance on Pt(111)

[0147] I. Experimental Methods

[0148] This experimental example involves placing an unmodified Pt(111) electrode into a container containing trace amounts of Cl. - Electrochemical reactions (e.g., CV scanning or ORR reaction) were carried out in an electrolyte solution to generate a Pt(111) electrode with a Cl submonolayer modified on the surface. The ORR activity of this Cl submonolayer-modified Pt(111) electrode was then investigated.

[0149] II. Experimental Results

[0150] Figure 5 The addition of trace amounts of Cl to 0.05 M H₂SO₄ demonstrates... - The effect on the basic CV curve and ORR polarization curve of Pt(111). Figure 5 Figure a shows the CV curves of Pt(111) in 0.05 M H2SO4 + x mM KCl. The dashed line represents the background CV of Pt(111) in 0.05 M H2SO4, which shows the basic characteristics of the unmodified Pt(111) single crystal surface in clean H2SO4.

[0151] Add a trace amount of Cl to 0.05M H2SO4 - At that time, Cl - The adsorption / desorption current occurs over a wide potential range (0.07-0.72V), causing it to compete with the adsorption of (bis)sulfates.

[0152] Figure 5 b shows the ORR polarization curves of Pt(111) in the corresponding electrolyte solution system in a positive sweep. (Compared to Cl...) - Contrary to the conventional understanding that it is a potent poison, adding trace amounts of Cl to 0.05M H2SO4... - The ORR performance on Pt(111) is significantly improved. Using a half-wave potential E1 / 2 As a standard for ORR performance, ORR performance increases with c Cl - increases first and then decreases. When c Cl- At 0.5 mM, ORR activity reached its maximum, with a 90 mV increase in the positive scan (+) and a 102 mV increase in the negative scan (-) compared to 0.05 M H2SO4.

[0153] Similar results were obtained in similar experiments conducted in 0.05 M H3PO4 and 0.10 M HClO4. First, let's focus on... Figure 5 The 0.05 M H3PO4 system in c and d. Background CV of Pt(111) in 0.05 M H3PO4 ( Figure 5 c) Consistent with the literature, phosphate adsorption / desorption occurred in the range of 0.25–0.60 V. The addition of Cl... - Subsequently, due to Cl at a lower potential - The adsorption of phosphates is hindered. In Cl... - At a concentration of 10 mM, the ORR performance on Pt(111) reached its peak, with E0.05M3PO4 showing a significant increase compared to the original concentration of 0.05 mM. 1 / 2 51mV(+) and 88mV(-) were added in the positive and negative scanning directions, respectively. Figure 5 d).

[0154] For the 0.10M HClO4 system, Figure 5 The background CV of Pt(111) in E also exhibits good characteristics. The current observed at E > 0.5 V is attributed to water adsorption / desorption on Pt(111). Adding a very small amount of Cl to 0.10 M HClO4... - It can inhibit the water adsorption process. When c Cl- At a concentration >0.1 mM, the Cl layer almost completely inhibited water adsorption; in HClO4, the Cl layer completely inhibited water adsorption. - The concentration was much lower than that of the H2SO4 and H3PO4 systems. Judging from the ORR activity, the addition of different concentrations of Cl... - The optimal ORR performance was achieved in 0.10 M HClO4 + 0.02 mM KCl, compared to that without Cl. - Compared to the situation in E 1 / 2 3mV(+) and 19mV(-) were added in the positive and negative scanning directions, respectively. Figure 5 f).

[0155] The above experimental results show that Cl - It can form a Cl sub-monolayer adsorption on the surface of Pt(111) electrode, thereby improving the ORR activity of the electrode.

[0156] Experimental Example 4: Trace Br - Impact on ORR performance on Pt(111)

[0157] I. Experimental Methods

[0158] The experimental method in this example is as described in Example 2, specifically including the following two parts:

[0159] 1. By placing an unmodified Pt(111) electrode into a container containing trace amounts of Br - Electrochemical reactions (e.g., CV scanning or ORR reactions) are carried out in electrolyte solutions to generate surface-modified Br. - A sub-monolayer Pt(111) electrode was used. The ORR activity of this Br-modified sub-monolayer Pt(111) electrode was also investigated.

[0160] 2. The Br-modified Pt(111) electrode (Pt(111)-Br*) was placed in HClO4 electrolyte solution for electrochemical reaction (e.g., CV scan or ORR reaction) to investigate the ORR activity of the Br-modified Pt(111) electrode with a Br submonolayer.

[0161] II. Experimental Results

[0162] Figure 6 The results show the Br content in 0.05 M H₂SO₄, 0.05 M H₃PO₄, and 0.10 M HClO₄. - Effect of ORR on Pt(111). The ORR activity of Pt(111) in 0.05 M H2SO4 at c Br- E = 5μM is optimal, with positive and negative scans showing the best performance. 1 / 2 They increased by 89 and 106 mV respectively. Figure 6 b). Similarly, in 0.05M H3PO4 ( Figure 6 c, d) and 0.10 M HClO4 ( Figure 6 In e,f), trace amounts of Br - It exhibits a promoting effect on ORR on Pt(111). 1 / 2 With c Br- The relationship between them is volcanic, and ORR activity is in c Br- It reaches its optimal value at 5 μM.

[0163] This experimental example also investigated the ORR activity of Pt(111)-Br* with different Br coverage in 0.10 M HClO4, such as Figure 7 As shown, the ORR activity of Pt(111)-Br* exhibits a volcano-like relationship with Br coverage. Compared to Pt(111) in 0.10 M HClO4, Pt(111)-Br* shows a higher ORR activity at E0.10.1 / 2 It exhibits a maximum enhancement of 21 mV(+), which is better than many other modifications of Pt(111) known in the art (such as cyanides, alkanes and aromatic organic molecules) (reference: Nat Chem 2010, 2, 880-885; Electrochemistry 2018, 86, 214-216).

[0164] The experimental results above show that, regardless of whether a trace amount of Br is directly added to the electrolyte solution... - Whether the ORR performance of the Pt electrode was significantly improved after modifying the Pt electrode surface with a sub-monolayer of Br or after the ORR test was performed, the optimal coverage range for modifying the Pt electrode surface with a sub-monolayer of Br was 0.53-0.95 mL, and the optimal coverage was 0.6 mL.

[0165] Experimental Example 5: Trace I under alkaline conditions - Impact on Pt ORR performance

[0166] I. Experimental Methods

[0167] The experimental method in this example is as described in Example 2. Specifically, unmodified Pt(111) electrodes, polycrystalline Pt electrodes, and nano Pt electrodes (purchased from Suzhou Shengernuo Technology Co., Ltd., SPT100) are placed in a solution containing trace amounts of I... - Electrochemical reactions (e.g., CV scanning or ORR reaction) were carried out in an electrolyte solution to generate a Pt electrode with a surface-modified I submonolayer. The ORR activity of this I submonolayer-modified Pt electrode was then investigated.

[0168] II. Experimental Results

[0169] like Figure 8 As shown in the upper images a, b, and c, the unmodified Pt(111) electrode, polycrystalline Pt electrode, and nano-Pt electrode exhibit standard CV images in 0.1M NaOH electrolyte solution. However, the addition of 3 μM NaI or 0.01 mM NaI to the electrolyte solution reduces the hydrogen and cation currents in the CV, indicating that some active sites on the Pt electrode surface are covered by I, meaning that an I-modified Pt electrode was successfully fabricated during the CV scan.

[0170] like Figure 8 As can be seen in the lower images a, b, and c, after surface modification I, all three types of Pt electrodes (Pt(111) electrode, polycrystalline Pt electrode, and nano Pt electrode) exhibit enhanced ORR activity. Among them, the Pt(111) electrode shows the highest ORR activity. k The half-wave potential shifted positively by 55mV, and the j of the polycrystalline Pt electrode... kThe half-wave potential shifted positively by 50mV, and the j of the nano-Pt electrode k The half-wave potential shifted positively by 31mV.

[0171] The experimental results show that, under alkaline conditions, modifying halogen elements can also enhance the ORR activity of Pt electrodes.

[0172] Experimental Example 6: ORR activity of Pt electrode with surface-modified sub-monolayer nitrogen-containing modifier

[0173] I. Experimental Methods

[0174] This experimental example investigated the ORR activity of a Pt electrode with a surface-modified sub-monolayer nitrogen-containing modifier prepared according to the method of Example 3 in 0.1M HClO4 electrolyte.

[0175] In comparison, this experimental example also prepared a nitrogen-containing modified Pt(111) electrode according to the method of Example 3:

[0176]

[0177] Electrochemical testing conditions were as follows: three-electrode glass cell, Pt wire as electrode, Ag / AgCl reference, and potentials converted to relative relative RHE. Electrolyte solutions: 0.1M HClO4, 0.1M HClO4 + 28mM t-BuNH2, +1mM TEMP, +5mM PMP. Electrolyte was saturated with Ar or O2, 50mV / s, 1600rpm, Autolab 302N instrument, 90% IR compensation. ORR activity was measured using a kinetic current of 0.9V. k , calculated using the K-L equation.

[0178] II. Experimental Results

[0179] 1. The promoting effect of nitrogen-containing modifiers on the ORR activity of Pt(111)

[0180] Figure 9 a. Provide the structure, abbreviation, and pKa of the modifier molecule used. Figure 10 (The same applies to a and d). Based on the number of N–H bonds, amines are classified as primary, secondary, and tertiary amines; pKa 3.9–11.25. In 0.1M HClO4, these modifier molecules all exist in protonated form. Figure 9 b, 11b, and e present the CVs of Pt(111) with maximum coverage, compared to bare Pt(111) (without any modification). The CV morphology is maintained after modification; the characteristics of the HUPD region (0.05–0.4V) and OH* region (0.6–1.0V) are weakened, indicating that the amine molecule adsorption covers the active sites.

[0181] Although the active sites are partially covered, the ORR polarization curve of the modified Pt(111) is ( Figure 9 e), 10c, and f) all shifted positively, indicating that the nitrogen-containing modifiers provided in Example 3 have a promoting effect on ORR activity. Among them, t-BuNH2 showed the best promoting effect, shifting the half-wave potential positively by 43 mV to 0.91 V; secondary and tertiary amines shifted by approximately 32 mV and 16 mV, respectively.

[0182] With a dynamic current of 0.9V j k And the comparative activity of enhancing factors. Naked Pt(111)j k Minimum; increases after amine modification. Activity order: t-BuNH2 > TEMP ≈ t-BuNHMe ≈ t-BuNH(i-Pr) ≈ DIBA > TEMPOH ≈ TEMPO ≈ PMP ≈ t-BuNDMe ≈ Lutidine. Compared to bare Pt(111), primary, secondary, and tertiary amines show apparent enhancements of approximately 4.5, 3.1, and 1.6 times, respectively; after normalization of active area, intrinsic enhancements are approximately 10.5, 5.4, and 2.7 times, respectively. 0.85V j k It also exhibits the same trend.

[0183] Other primary amines used as controls, such as IPA, EA (with H attached to α-C), or PhNH2 and 2,6-DMA (α-C being a benzene ring), did not significantly promote ORR activity. Figure 10 c, f). Although IPA and EA are primary amines, their high water solubility leads to easy desorption after the electrode is immersed in the electrolyte; therefore, no promoting effect was observed. Figure 10 (b, c) When 20 mM IPA or EA is added to the solution, IPA exhibits a similar promoting effect to t-BuNH2, while EA is oxidized to CN. ad The site is poisoned without promoting adsorption. Therefore, alkyl groups (e.g., methyl groups) should be introduced into the α-C of nitrogen-containing modifiers to enhance stability and ensure adsorption.

[0184] Although aniline and 2,6-dimethylamine are primary amines and can be stably adsorbed, they have no promoting effect. Figure 10 e, f) The reason may be that the benzene ring is adsorbed while lying flat, occupying too many active sites.

[0185] In summary, nitrogen-containing modifier molecules with promoting effects must meet the following requirements: 1) nitrogen content as a proton anchor; 2) absence of α-H on the α-C to ensure stable adsorption; 3) at least one alkyl group (such as methyl) attached to the α-C to provide a hydrophobic environment; and 4) substituents attached to nitrogen that do not contain benzene rings or conjugated structures. Under these structural constraints, TEMP, t-BuNHMe, t-BuNH(i-Pr), DIBA, TEMPOH, PMP, t-BuNDMe, and Lutidine, all containing the t-BuNH2 local structure provided in Example 3, can enhance ORR activity.

[0186] 2. The promoting effect of nitrogen-containing modifiers on the ORR activity of Pt(111) and polycrystalline Pt under alkaline conditions.

[0187] The behavior differs under alkaline conditions from that under acidic conditions. Figure 11 At pH 13, the amine was not protonated. The HUPD and OH* regions of t-BuNH2-modified Pt(111) were simultaneously suppressed, shifting the ORR half-wave potential positively by 38 mV. Figure 11 b). In electrolyte solutions containing t-BuNH2, the ORR activity of polycrystalline Pt exhibits a volcanic pattern with increasing t-BuNH2 concentration, reaching its maximum at 0.05 mM, where it increases approximately fourfold. Figure 11 d). The ORR activity of Pt nanoparticles (purchased from Suzhou Shengernuo Technology Co., Ltd., SPT100) reached its maximum at 0.05 mM, representing an approximately 2-fold increase. Figure 11 f).

[0188] The experimental results above show that modifying the Pt electrode surface with nitrogen-containing modifiers with specific structural characteristics can significantly improve the ORR performance of the Pt electrode.

[0189] As can be seen from the above embodiments and experimental examples, this invention provides a modification scheme for Pt-based electrodes using modifiers containing halogen elements. By modifying the surface of the Pt-based electrode with a sub-monolayer of halogen elements, the catalytic performance of the Pt-based electrode for the oxygen reduction reaction can be significantly improved. This invention provides new ideas and strategies for the design of oxygen reduction catalysts for fuel cells and has good application prospects.

Claims

1. A modified platinum-based oxygen reduction catalyst, characterized in that: This includes platinum-based catalysts, the surface of which is coated with a halogen-containing or nitrogen-containing modifier. The nitrogen-containing modifier is a compound of formula I or II or a salt thereof: Among them, R1 and R2 are independently selected from C1-C 10 Alkyl groups; R3 is selected from C1-C 10 Alkyl groups; R4 is selected from H, C1-C 10 Alkyl, C1-C 10 The amino group; Alternatively, R3 and R4 may be linked to form a substituted or unsubstituted 5-10 membered nitrogen-containing heterocycle, wherein the substituents are selected from C1-C2. 10 Alkyl groups; R5 is selected from H, hydroxyl group, oxygen free radical, C1-C. 10 Alkyl groups; Ring A is selected from substituted or unsubstituted 6-10 member nitrogen-containing heteroaryl groups, wherein the substituents are selected from C1-C2. 10 Alkyl groups; R6 and R7 are independently selected from C1-C1. 10 Alkyl groups.

2. The modified platinum-based oxygen reduction catalyst according to claim 1, characterized in that: The halogen-containing modifier is selected from one or a combination of at least two of halogen atoms, halide anions, halogen-containing molecules, or halogen-containing anions; the halogen atom is selected from one or a combination of at least two of Cl, Br, or I; and the halide anion is selected from Cl... - ,Br - Or I - One or at least two of them; When the halogen-containing modifier is selected from I or I - The halogen-containing modifier has a coverage of less than or equal to 0.5 mL, and is in combination with one or at least two of the halogen-containing elements. When the halogen-containing modifier is selected from Cl, Cl - Br or Br - The halogen-containing modifier has a coverage of less than or equal to 0.95 mL, and is a combination of one or at least two of the halogen-containing modifiers.

3. The modified platinum-based oxygen reduction catalyst according to claim 1, characterized in that: The platinum-based catalyst is composed of elemental Pt or Pt-containing alloy materials; the Pt-containing alloy materials are selected from one or a combination of at least two of the following alloys: PtNi alloy, PtCo alloy, PtFe alloy, or PtCu alloy. When the crystal orientation of the platinum-based catalyst surface includes Pt(111), the halogen-containing modifier is selected from I or I - The halogen-containing modifier has a coverage of less than or equal to 0.37 mL, consisting of one or at least two of the halogen-containing elements. When the crystal orientation of the platinum-based catalyst surface includes Pt(332), the halogen-containing modifier is selected from I or I - The halogen-containing modifier has a coverage of less than or equal to 0.28 mL, consisting of one or at least two of the halogen-containing elements. When the crystal orientation of the platinum-based catalyst surface includes Pt(111), the halogen-containing modifier is selected from Br or Br₂. - The halogen-containing modifier has a coverage of less than or equal to 0.6 mL, and is a combination of one or at least two of the halogen-containing modifiers.

4. The modified platinum-based oxygen reduction catalyst according to claim 1, characterized in that: The modified platinum-based oxygen reduction catalyst is prepared by immersing the platinum-based catalyst in an aqueous solution containing halides or halogen elements, controlling the coverage of halogen anions or halogen atoms by immersion time, and then cleaning the platinum-based catalyst to obtain the catalyst. Alternatively, the modified platinum-based oxygen reduction catalyst can be prepared by immersing the platinum-based catalyst in a solution of a nitrogen-containing modifier, controlling the coverage of the nitrogen-containing modifier by the immersion time, and then washing the platinum-based catalyst to obtain the catalyst.

5. The modified platinum-based oxygen reduction catalyst according to claim 1, characterized in that: The modified platinum-based oxygen reduction catalyst is prepared by spin-coating an aqueous solution containing a halide or halogen element onto the surface of the platinum-based catalyst, controlling the coverage of halogen anions or halogen atoms by the amount of spin-coating, and then evaporating the solution to obtain the catalyst. Alternatively, the modified platinum-based oxygen reduction catalyst can be prepared by spin-coating a solution of a nitrogen-containing modifier onto the surface of the platinum-based catalyst, controlling the coverage of the nitrogen-containing modifier by the amount of spin-coating, and then evaporating the solution to obtain the catalyst.

6. The modified platinum-based oxygen reduction catalyst according to claim 1, characterized in that, The nitrogen-containing modifier is selected from:

7. The modified platinum-based oxygen reduction catalyst according to claim 1, characterized in that, The coverage of the nitrogen-containing modifier is less than or equal to 0.6 mL.

8. A method for preparing the modified platinum-based oxygen reduction catalyst according to any one of claims 1-17, characterized in that, The process includes the following steps: immersing the platinum-based catalyst in an aqueous solution containing halides or elemental halogens, controlling the coverage of halogen anions or halogen atoms by controlling the immersion time, and then cleaning the platinum-based catalyst to obtain the final product. Alternatively, the platinum-based catalyst can be immersed in a solution of a nitrogen-containing modifier, and the coverage of the nitrogen-containing modifier can be controlled by the immersion time. After rinsing the platinum-based catalyst, the product can be obtained. Alternatively, the modified platinum-based oxygen reduction catalyst can be prepared by spin-coating an aqueous solution containing a halide or halogen element onto the surface of the platinum-based catalyst, controlling the coverage of halogen anions or halogen atoms by the amount of spin-coating, and then evaporating the solution to obtain the catalyst. Alternatively, a solution of a nitrogen-containing modifier can be spin-coated onto the surface of the platinum-based catalyst, and the coverage of the nitrogen-containing modifier can be controlled by the amount of spin-coating. The solution can then be evaporated to obtain the final product.

9. Use of the modified platinum-based oxygen reduction catalyst according to any one of claims 1-7 for the preparation or as an oxygen reduction electrocatalyst.

10. A fuel cell, characterized in that: The fuel cell uses the modified platinum-based oxygen reduction catalyst as described in any one of claims 1-7 as the cathode electrocatalyst.

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