Copper-based catalyst for fuel cell cathode as well as preparation method and application of copper-based catalyst

Abstract

The invention provides a copper-based catalyst for a fuel cell cathode as well as a preparation method and application of the copper-based catalyst, and the preparation method comprises the following steps: preparing 3, 5-diamino-1, 2, 4-triazole copper complex powder; and carrying out pulse laser treatment on the 3, 5-diamino-1, 2, 4-triazole copper complex powder, so as to obtain the 3, 5-diamino-1, 2, 4-triazole copper complex powder. The analysis of ICP-MS, TGA and XPS shows that the pulsed laser treatment eliminates at least a portion of water molecules coordinated with adjacent copper atoms, which results in an increase in oxygen vacancies between adjacent copper atoms, enhancing the preference of "side-to-" O2 adsorption configurations, thus promoting the cleavage of O-O bonds during ORR. Therefore, the 3, 5-diamino-1, 2, 4-triazole copper complex treated by the pulse laser shows higher four-electron pathway selectivity than the 3, 5-diamino-1, 2, 4-triazole copper complex before treatment.

Description

Technical Field

[0001] This invention relates to a copper-based catalyst for fuel cell cathodes, its preparation method, and its application. Background Technology

[0002] Global warming has become a global challenge, profoundly impacting the Earth's ecology and human life. Against this backdrop, the demand for sustainable and clean energy is increasingly urgent, and fuel cells, as a highly efficient and environmentally friendly energy solution, are receiving growing attention.

[0003] Fuel cells directly convert the chemical energy in fuel into electrical energy through an electrochemical reaction. This process produces no carbon emissions and allows for rapid recharging, providing a clean and efficient energy solution for vehicles and other transportation. However, the commercialization of fuel cells is still limited by some key technologies, among which the slow nature of the oxygen reduction reaction (ORR) is a significant bottleneck.

[0004] ORR is a reduction process that converts oxygen into water or hydrogen peroxide via either a 4-electron or a 2-electron pathway.

[0005] 4-electron pathway: O2 + 2H2O + 4e - →4OH -

[0006] 2-electron pathway: O2 + H2O + 2e - →OH2 - +OH -

[0007] At the cathode of a fuel cell, the 4-electron reduction pathway is more ideal because it enables a more complete energy conversion from O2 to H2O, thereby increasing the power output of the fuel cell. However, in practical applications, ORR often faces competition from the 2-electron pathway, making it challenging to improve product selectivity and energy conversion efficiency.

[0008] The use of traditional catalysts, such as platinum, faces challenges due to high cost and limited availability. As a precious metal, platinum is expensive to mine and process, and its reserves on Earth are limited, making it difficult to reduce the production cost of fuel cells, thus limiting their potential for large-scale commercialization.

[0009] To overcome these challenges, researchers are actively seeking efficient, economical, highly selective, and environmentally friendly alternative electrochemical catalysts for ORR (Organic Regenerative Catalysis). These novel catalysts include transition metal oxides and carbon-based materials, which are characterized by low cost, abundant reserves, and excellent catalytic performance. By optimizing the structure and composition of the catalysts, the activity and selectivity of ORR can be further improved, thereby advancing the commercialization of fuel cell technology.

[0010] The method proposed by Mano et al., which connects laccase to redox hydrogels, has brought a new breakthrough to fuel cell technology. This strategy has successfully developed an ORR catalytic composite material with performance superior to platinum. Laccase, as a biological enzyme, owes its remarkable ORR catalytic performance primarily to its unique active center structure, a complex structure composed of 3 copper atoms and 8 histidine residues. Copper, as an abundant metallic element on Earth, is far less expensive than the precious metal platinum, thus possessing great potential to replace platinum as an ORR catalyst. However, the application of laccase is limited because it is based on enzyme properties and requires processing under mild conditions. Therefore, directly using laccase in the corrosive environment of fuel cell systems is impractical. Consequently, mimicking the catalytic performance of laccase through transition metal complexes has become an important research topic.

[0011] Nitrogen / oxygen / sulfur-containing ligands, such as porphyrins, tris(2-pyridinemethyl)amines, substituted 1,10-phenanthrolines, and derived 1,2,4-triazoles, have been used to coordinate with copper to form ORR catalysts. Among these attempts, the 3,5-diamino-1,2,4-triazole copper complex (CuTRZDA) has been identified as an effective ORR catalyst due to its excellent catalytic performance, high pH tolerance, and low cost. However, the catalytic performance of CuTRZDA still lags behind that of the bioenzyme laccase, indicating that there is still room for improvement in the design and optimization of such catalysts. Currently, although researchers have attempted to modify and optimize the ligands through molecular customization to improve catalyst performance, the results have not been satisfactory. This may mean that simply changing the ligands cannot completely solve the problem, and other enhancement methods need to be explored.

[0012] Goenaga et al. conducted an in-depth study on the synthesis parameters of CuTRZDA. By carefully adjusting the copper salt counterions and the pretreatment method of carbon black, they successfully optimized the catalyst performance. Experimental results showed that CuTRZDA exhibited the best catalytic performance when CuSO4 and Cu(BF4)2 were used as reactants. Furthermore, prior to the preparation of the catalyst ink, pretreatment of carbon black with hydrogen peroxide and sulfuric acid improved the onset potential and current density.

[0013] On the other hand, Asakura et al. used in-situ X-ray absorption near-edge structure measurement to investigate in detail the changes in the coordination geometry of CuTRZDA at different pH values. They found that, compared with pH 7 and pH 10, at pH 13, the coordination geometry of CuTRZDA changed significantly due to deprotonation, resulting in a lower overpotential at this pH value.

[0014] In addition, heat treatment has been used to improve the catalytic performance of CuTRZDA. Hashimoto et al. treated a mixture of CuTRZDA and carbon black at 900 °C for 45 seconds in an argon atmosphere, which resulted in the heat-treated CuTRZDA / C sample exhibiting better onset potential and durability.

[0015] In summary, the research by Goenaga, Asakura, Hashimoto, and others has explored and optimized the catalytic performance of CuTRZDA from different perspectives, demonstrating that CuTRZDA is a promising ORR catalyst whose performance can be further improved through other enhancement methods. Summary of the Invention

[0016] Therefore, the purpose of this invention is to propose a new method to improve the performance of CuTRZDA catalysts based on existing research.

[0017] Through in-depth literature review and extensive experimental exploration, the inventors of this invention have surprisingly discovered that pulsed laser treatment of CuTRZDA powder significantly enhances the ORR catalytic activity, particularly the 4-electron pathway selectivity. Further analysis using ICP-MS, TGA, and XPS revealed that pulsed laser treatment removes at least a portion of the water molecules coordinated to adjacent copper atoms. This leads to an increase in oxygen vacancies between adjacent copper atoms, enhancing the preference for the "side-opposite" O2 adsorption configuration and promoting the breaking of OO bonds during ORR.

[0018] Based on this, the first aspect of the present invention provides a method for preparing a copper-based catalyst for a fuel cell cathode, the method comprising the following steps:

[0019] (1) Preparation of 3,5-diamino-1,2,4-triazole copper complex powder;

[0020] (2) The 3,5-diamino-1,2,4-triazole copper complex powder was subjected to pulsed laser treatment.

[0021] According to the preparation method provided by the present invention, the laser power of the pulsed laser treatment can be 1 to 6 W, preferably 2 to 4 W.

[0022] According to the preparation method provided by the present invention, the laser repetition frequency of the pulsed laser treatment can be 10-500 kHz, preferably 100-300 kHz.

[0023] According to the preparation method provided by the present invention, the laser scanning rate of the pulsed laser processing can be 50-1000 mm / s, preferably 100-400 mm / s; the line spacing of the laser scanning can be 0.005-0.100 mm.

[0024] According to the preparation method provided by the present invention, the diameter of the laser spot used in the pulsed laser processing can be 0.01-0.10 mm.

[0025] According to the preparation method provided by the present invention, the pulse width used in the pulsed laser processing can be 1-20 ns.

[0026] According to the preparation method provided by the present invention, the 3,5-diamino-1,2,4-triazole copper complex powder can be prepared in step (1) using methods commonly used in the art. For example, the 3,5-diamino-1,2,4-triazole copper complex powder can be prepared in step (1) by performing a complexation reaction between 3,5-diamino-1,2,4-triazole and a copper salt.

[0027] In a preferred embodiment of the present invention, step (1) may include: dissolving 3,5-diamino-1,2,4-triazole in a solvent, and then adding a copper salt solution. During the reaction, the reaction may be promoted by stirring or heating.

[0028] The copper salt may be selected from one or more of copper sulfate, copper chloride, copper nitrate, copper carbonate, copper acetate, and copper acetate. The solvent may be one or more of water, ethanol, and methanol.

[0029] In a preferred embodiment of the present invention, step (1) may further include: after the reaction is complete, separating the generated 3,5-diamino-1,2,4-triazole copper complex from the reaction solution by an appropriate separation method (such as filtration, centrifugation, etc.). The separated complex can be further purified by recrystallization, washing, and other steps to improve its purity and stability.

[0030] In a preferred embodiment of the present invention, step (1) further includes: separating and purifying the obtained 3,5-diamino-1,2,4-triazole copper complex, drying it and grinding it into powder.

[0031] A second aspect of the present invention provides a copper-based catalyst for a fuel cell cathode prepared by the above-described preparation method.

[0032] A third aspect of the present invention provides a method for improving the catalytic performance of a copper-based catalyst for a fuel cell cathode, wherein the copper-based catalyst is a 3,5-diamino-1,2,4-triazole copper complex powder, and the method includes: subjecting the 3,5-diamino-1,2,4-triazole copper complex powder to pulsed laser treatment.

[0033] The method for improving the catalytic performance of a copper-based catalyst for a fuel cell cathode according to the present invention includes 4-electron pathway selectivity.

[0034] According to the method for improving the catalytic performance of copper-based catalysts for fuel cell cathodes provided by the present invention, X-ray photoelectroluminescence spectroscopy (XPS) shows that the binding energy peak of the 932.8 eV binding energy peak of the 3,5-diamino-1,2,4-triazole copper complex after pulsed laser treatment is greater than that of the original CuTRZDA. This result indicates that the pulsed laser treatment increases the number of unsaturated coordinated copper central atoms in the 3,5-diamino-1,2,4-triazole copper complex.

[0035] The fourth aspect of the present invention provides the application of a copper-based catalyst for a fuel cell cathode prepared according to the preparation method described in the first aspect of the present invention in the oxygen reduction reaction on the cathode side of a fuel cell.

[0036] This invention produces a novel ORR electrocatalyst (hereinafter referred to as "PL-CuTRZDA") by treating 3,5-diamino-1,2,4-triazole copper complex (CuTRZDA) powder with a pulsed laser. Compared with the original CuTRZDA, PL-CuTRZDA exhibits at least a 7% improvement in 4-electron pathway selectivity. In some embodiments, the 4-electron pathway selectivity of PL-CuTRZDA can reach 94%, making it a more suitable cathode catalyst for fuel cell systems. ICP-MS, TGA, and XPS analyses show that pulsed laser treatment eliminates water molecules coordinated to adjacent copper atoms, leading to an increase in oxygen vacancies between adjacent copper atoms, enhancing the preference for "side-pair" O2 adsorption configurations, thereby promoting the breaking of OO bonds during ORR. Therefore, PL-CuTRZDA exhibits a higher 4-electron pathway selectivity than the original CuTRZDA. Attached Figure Description

[0037] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0038] Figure 1 The images are TEM images (a) and (d) of the raw CuTRZDA (left) prepared in step (1) and the PL-CuTRZDA (right) prepared in step (2) of Example 1; SEM images (b) and (e); and SEM-EDS elemental spectra (c) and (f).

[0039] Figure 2 The disk current density and ring current density of the original CuTRZDA and PL-CuTRZDA, as well as the blank ink containing only Vulcan XC-72 carbon, were measured in Example 7 (Figure a); and the product selectivity was shown in Figure b.

[0040] Figure 3The figures show the liquid chromatograms of the TRZDA solution, PL-CuTRZDA, and raw CuTRZDA from Example 8; the mass spectra of the TRZDA solution with a retention time of 1.82 min; and the mass spectra of the TRZDA solution, PL-CuTRZDA, and raw CuTRZDA with a retention time of 2.1 min. [Please replace the English text in the figures with Chinese text.]

[0041] Figure 4 The figure shows the ICP-MS standard curve (dashed line) for copper in Example 8, as well as the copper concentrations in the original CuTRZDA (triangle) and PL-CuTRZDA (square).

[0042] Figure 5 Thermogravimetric analysis (TGA) curves (a) and derivative thermogravimetric analysis (DTG) curves (b) of the original CuTRZDA and PL-CuTRZDA in Example 8 are shown.

[0043] Figure 6 Cu in the original CuTRZDA and PL-CuTRZDA in Example 8 2p XPS spectra.

[0044] Figure 7 This provides structural information about the coordination water bound in CuTRZDA.

[0045] Figure 8 This is a schematic diagram of three common O2 adsorption configurations and their corresponding oxygen reduction pathways in PL-CuTRZDA catalysts. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0047] All chemicals used in the embodiments of this invention were purchased from the supplier and used as is without additional purification. To prepare an aqueous solution with a pH of 13 for electrochemical experiments, Milli-Q pure water (>18 MΩcm) and KOH (ACS reagent grade, Aladdin) were used. Before conducting the electrochemical experiments, the aqueous solution was sprayed with 99.5% pure oxygen (Linde HKO) for 15 minutes.

[0048] Example 1

[0049] Preparation of copper-based catalyst for fuel cell cathode according to the present invention

[0050] (1) Preparation of copper complex of 3,5-diamino-1,2,4-triazole (CuTRZDA)

[0051] 0.200 g of CuSO4·5H2O (ACS reagent grade, J&K) and 0.159 g of 3,5-diamino-1,2,4-triazole (TRZDA, 98%, J&K) were dissolved separately in 10 mL of Milli-Q purified water. The CuSO4 solution was then added dropwise to the TRZDA solution, and the mixture was sonicated for 30 minutes. The resulting green suspension was then centrifuged at 8000 rpm for 5 minutes to obtain a green precipitate. The product was washed three times with Milli-Q purified water, dried in a vacuum oven at 85°C for 20 hours, and then the CuTRZDA product was ground into a fine powder.

[0052] (2) Preparation of CuTRZDA (PL-CuTRZDA) by pulsed laser treatment

[0053] The CuTRZDA powder obtained in step (1) was processed using a fiber pulsed laser (model MS-20W, Shenzhen Minsheng Laser Technology Co., Ltd.) with a wavelength of 1064nm.

[0054] CuTRZDA powder was uniformly placed on a transparent acrylic plate, and then treated with a pulsed laser in air atmosphere using a specified parameter combination. The pulsed laser treatment parameters used in this embodiment are as follows:

[0055] The laser power is 2W, the repetition rate is 200kHz, the laser scanning speed is 200mm / s, and the spacing is 0.01mm. The laser spot diameter is 0.05mm, and the pulse width is 5ns.

[0056] The product after pulsed laser treatment is called pulsed laser treated CuTRZDA (abbreviated as PL-CuTRZDA).

[0057] Example 2

[0058] The copper-based catalyst for the fuel cell cathode of the present invention was prepared using a method similar to that in Example 1, except that the pulsed laser processing parameters used in this example are as follows:

[0059] The laser power is 1W, the repetition rate is 50kHz, the laser scanning speed is 500mm / s, and the spacing is 0.005mm. The laser spot diameter is 0.1mm, and the pulse width is 1ns.

[0060] Example 3

[0061] The copper-based catalyst for the fuel cell cathode of the present invention was prepared using a method similar to that in the embodiments, except that the pulsed laser processing parameters used in this embodiment are as follows:

[0062] The laser power is 4W, the repetition rate is 50kHz, the laser scanning speed is 100mm / s, and the spacing is 0.1mm. The laser spot diameter is 0.1mm, and the pulse width is 15ns.

[0063] Example 4

[0064] Preparation of electrocatalyst ink

[0065] The PL-CuTRZDA obtained in Examples 1-3 were respectively used to prepare electrocatalyst inks, and the preparation process is as follows:

[0066] (1) The copper complex (4 mg) and Vulcan XC-72 carbon (16 mg) were mixed in 1 mL of ethanol. After sonication for 10 minutes, the resulting mixture was dried at 60 °C for 12 hours.

[0067] (2) Add 4 mg of the obtained powder to 1 mL of ethanol and sonicate for 10 minutes. Then add 4 μL of Nafion. TM The perfluorinated resin was then sonicated for 10 minutes to form a uniform suspension, which was then used as a catalyst ink in subsequent tests.

[0068] Example 5

[0069] Electrochemical testing

[0070] All electrochemical experiments were performed using a CH Instruments 760E electrochemical workstation and a rotating ring-disk electrode (RRDE) system (Wavevortex, Pine Research) in 0.1M KOH solution at 1600 rpm.

[0071] A three-chamber sample cell with a Luggin capillary was used to separate the reference electrode and the working electrode. The working electrode was a glass carbon disk electrode (area = 0.196 cm²). 2 A rotating ring-disk electrode (RRDE) was used, with a platinum ring electrode as an auxiliary electrode to capture in-situ generated H2O2. An Ag / AgCl (3M KCl, ESA) electrode was used as a reference electrode, and a graphite rod was used as the counter electrode.

[0072] Compare with the reporting potential of the reversible hydrogen electrode (RHE). The product selectivity of the oxygen reduction reaction (ORR) was calculated based on the measured ring current and disk current.

[0073] Example 6

[0074] Material characterization

[0075] (1) Transmission electron microscopy (TEM) characterization was performed using a FEI Tecnai G2 20 scanning transmission electron microscope.

[0076] (2) Scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS) analyses were performed using a Hitachi S4800 FEG scanning electron microscope.

[0077] (3) Samples for inductively coupled plasma mass spectrometry (ICP-MS) and liquid chromatography-mass spectrometry (LC-MS) were dissolved in 1 mL of 10% HNO3 to form a 1000 ppm solution. The sample solution was then diluted 10,000 times (for ICP-MS) and 100 times (for LC-MS).

[0078] (4) X-ray emission spectroscopy (XPS) was performed using the Thermo Scientific Nexsa G2 surface analysis system to obtain the surface atomic ratios of different elements.

[0079] (5) Thermogravimetric analysis (TGA) was performed using Mettler Toledo Model TGA / DSC 1.

[0080] (6) Perform elemental analysis (EA) using the Elementar Unicube elemental analyzer.

[0081] Material characterization results and analysis

[0082] TEM images show the aggregated structures of the pristine CuTRZDA prepared in step (1) and the PL-CuTRZDA prepared in step (2) of Example 1, as follows: Figure 1 As shown in Figures (a) and (b).

[0083] Similar morphologies were also observed in scanning electron microscope images, such as Figure 1 As shown in Figures (b) and (e), although small particles are present in the SEM images of PL-CuTRZDA, larger particles can still be observed. SEM-EDX spectra ( Figure 1 Figures (c) and (f) show that the C, N, S, Cu and O are uniformly distributed on the original CuTRZDA and PL-CuTRZDA particles, indicating that the composition of both materials is CuTRZDA and that pulsed laser treatment did not cause decomposition.

[0084] Example 7

[0085] Oxygen Reduction Reaction (ORR) Performance Testing

[0086] The electrocatalytic performance of the original CuTRZDA prepared in step (1) and the PL-CuTRZDA prepared in step (2) of Example 1 was tested using a rotating ring-disk electrode (RRDE) running at 1600 rpm in a 0.1 M KOH solution saturated with O2, and compared with a blank sample using only Vulcan XC-72 carbon.

[0087] The inks prepared in Example 4, containing pristine CuTRZDA and PL-CuTRZDA, and a blank ink containing only Vulcan XC-72 carbon, were uniformly drop-cast onto a disk electrode to catalyze ORR. Simultaneously, the platinum ring electrode promoted the oxidation of H2O2, allowing for the measurement of the amount of H2O2 generated during ORR. The number of transferred electrons and ORR product selectivity were then calculated from the recorded disk and ring currents.

[0088] The results are as follows Figure 2 As shown in Figure (a), the bottom of Figure (a) shows the disk current density and the top shows the ring current density. The dashed line represents the original CuTRZDA, the solid line represents PL-CuTRZDA, and the dotted line represents Vulcan XC-72 carbon.

[0089] Both pristine CuTRZDA and PL-CuTRZDA exhibited an onset potential 110 mV higher than Vulcan, indicating a significant improvement in catalytic activity compared to a carbon background. Pristine CuTRZDA showed a product selectivity of approximately 87% for H₂O, far exceeding Vulcan's approximately 38%. This result suggests that pristine CuTRZDA, with its good activity and 4-electron pathway selectivity, is suitable as an ORR catalyst for fuel cell systems. After pulsed laser treatment, PL-CuTRZDA further improved its 4-electron pathway selectivity to 94% (see...). Figure 2 (Figure (b)). This high selectivity indicates that PL-CuTRZDA is superior to CuTRZDA as a cathode catalyst for fuel cells.

[0090] Example 8

[0091] Mechanism study of PL-CuTRZDA enhancing 4-electron pathway selectivity

[0092] (I) The integrity of the TRZDA ligands and the copper content of the PL-CuTRZDA prepared in Example 1 of this invention after ORR were detected by liquid chromatography-mass spectrometry (LC-MS) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The results are as follows: Figure 3 As shown.

[0093] Figure 3In Figure (a), the three spectral lines from top to bottom are the liquid chromatograms of TRZDA solution, PL-CuTRZDA, and original CuTRZDA; Figure 3 Figure (b) is the mass spectrum of the TRZDA solution with a retention time of 1.82 minutes; Figure 3 Figure (c) shows, from top to bottom, the mass spectra of TRZDA solution with a retention time of 2.1 min, PL-CuTRZDA, and pristine CuTRZDA. The mass spectra were performed in positive ion mode.

[0094] Figure 3 Figure (a) shows the liquid chromatography results for TRZDA solution, PL-CuTRZDA, and pristine CuTRZDA, with two retention time bands observed at 1.8 min and 2.1 min. At a retention time of 2.1 min, a TRZDA peak at 100 m / z was observed in the mass spectrum. Figure 3 Figure (b) shows that the retention time of the TRZDA ligand is 2.1 minutes, as... Figure 3 As shown in Figure (c). The presence of intact TRZDA ligands in the original CuTRZDA and PL-CuTRZDA samples indicates that the TRZDA ligands remain unchanged after pulsed laser treatment. Figure 3 (The two spectra at the bottom of figure (c)). This LC-MS result shows that the molecular structure of TRZDA was preserved after pulsed laser treatment.

[0095] (ii) The copper content in raw CuTRZDA and PL-CuTRZDA was analyzed using ICP-MS, such as... Figure 4 As shown.

[0096] Figure 4 The ICP-MS standard curve for copper is shown (dashed line), along with the copper concentrations in the original CuTRZDA (triangle) and PL-CuTRZDA (square). Tables and insets both show the copper concentrations in 1000 ppm CuTRZDA and PL-CuTRZDA solutions. Sample dilutions have been calibrated. The graph shows that the copper concentration in PL-CuTRZDA is 5% higher than that in the original CuTRZDA. The increased weight fraction of copper observed in PL-CuTRZDA indicates that pulsed laser treatment caused some mass loss.

[0097] (III) To assess the mass loss at different temperatures, thermogravimetric analysis (TGA) was performed under a N2 atmosphere. The results are as follows: Figure 5 As shown, (a) is the thermogravimetric analysis (TGA) curve of the original CuTRZDA and PL-CuTRZDA, and (b) is the derivative thermogravimetric analysis (DTG) curve.

[0098] Figure 5Figure (a) shows that at 900 °C, the total mass losses of CuTRZDA and PL-CuTRZDA are 73.1% and 72.0%, respectively. This is based on the derivative thermogravimetric (DTG) curves. Figure 5 Figure (b) shows that the mass loss curve can be divided into three main steps: (i) in the temperature range of 60 to 200 °C, involving the removal of free water, lattice water, and coordinated water; (ii) in the temperature range of 200 to 400 °C, resulting in significant mass loss due to the decomposition of TRZDA; and (iii) in the temperature range of 530 to 630 °C, due to the decomposition of SO42-. 2- The decomposition of CuTRZDA results in mass loss at higher temperatures. The most significant difference was observed in step (i) by comparing the TGA curves of the original CuTRZDA and PL-CuTRZDA. The mass loss of the original CuTRZDA was 16.0%, while that of PL-CuTRZDA was 11.5%, indicating that pulsed laser treatment altered the water content.

[0099] (iv) Using Cu 2p X-ray photoemission spectroscopy (XPS) is used to study the properties of water removed from CuTRZDA molecules because it is highly sensitive to changes in the electronic structure of Cu complexes. For example... Figure 6 As shown in Figure (a), the Cu of the original CuTRZDA 2p The XPS plots matched the reported results very well; however... Figure 6 In Figure (b), the binding energy peak of 932.8 eV for PL-CuTRZDA is greater than that of the original CuTRZDA, indicating an increase in the number of unsaturated copper centers in PL-CuTRZDA. Therefore, the loss of water content can be attributed to the removal of coordinated water after pulsed laser treatment.

[0100] Based on existing CuTRZDA structure information, such as Figure 7 As shown, there are five water molecule coordination sites in CuTRZDA, which can be divided into two types: Type I coordinates with a single Cu (water in the solid box), and Type II bridges between two Cu centers (water in the dashed box).

[0101] Figure 8 The following diagram illustrates three common adsorption configurations of O2 in the PL-CuTRZDA catalyst and their corresponding oxygen reduction pathways: Yeager, Griffiths, and Pauling. Pauling-type adsorption is a chemisorption mode where oxygen molecules are adsorbed end-paired onto the metal surface, and its oxygen reduction process favors a 2-electron pathway. Griffiths-type and Yeager-type adsorption are side-paired adsorption modes, parallel to the metal surface, belonging to physisorption modes, and their oxygen reduction processes favor a 4-electron pathway.

[0102] During ORR, the Cu center can combine with *OH groups to form a type I configuration. Therefore, even if type I coordinated water is removed after pulsed laser treatment, it can be replenished as the reaction proceeds. However, the recovery probability of type II coordinated water is much lower than that of type I coordinated water. Therefore, the removal of type II coordinated water favors the formation of "side-paired" O2 adsorption configurations (i.e., Griffiths and Yeager types), promoting the cleavage of the OO bond. This mechanism explains the increased selectivity for the 4-electron pathway observed in the PL-CuTRZDA electrocatalyzed ORR process.

[0103] The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions and improvements made without departing from the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a copper-based catalyst for a cathode of a fuel cell, the method comprising the steps of: (1) preparing a 3,5-diamino-l,2,4-triazole copper complex powder; (2) subjecting the 3,5-diamino-l,2,4-triazole copper complex powder to a pulsed laser treatment.

2. The production method according to claim 1, wherein The pulsed laser treatment has a laser power of 1 to 6 W, preferably 2 to 4 W.

3. The production method according to claim 1 or 2, wherein The pulsed laser treatment has a laser repetition rate of 10 to 500 kHz, preferably 100 to 300 kHz.

4. The production method according to any one of claims 1 to 3, wherein, The pulsed laser treatment has a laser scanning rate of 50 to 1000 mm / s, preferably 100 to 400 mm / s.

5. The production method according to any one of claims 1 to 4, wherein, The pulsed laser treatment uses a scanning line distance of 0.005 to 0.100 mm.

6. The production method according to any one of claims 1 to 5, wherein, The pulsed laser treatment uses a laser spot diameter of 0.01 to 0.10 mm.

7. The production method according to any one of claims 1 to 6, wherein The pulsed laser treatment uses a pulse width of 1 to 20 ns.

8. The production method according to any one of claims 1 to 7, wherein The 3,5-diamino-l,2,4-triazole copper complex powder is prepared in step (1) by subjecting 3,5-diamino-l,2,4-triazole to a complexation reaction with a copper salt.

9. The production method according to claim 8, wherein Step (1) comprises dissolving 3,5-diamino-l,2,4-triazole in a solvent, and then adding a copper salt solution.

10. The production method according to claim 9, wherein The copper salt is selected from one or more of copper sulfate, copper chloride, copper nitrate, copper carbonate, copper acetate, and copper acetate.

11. The production method according to claim 9, wherein The solvent is one or more of water, ethanol, and methanol.

12. A copper-based catalyst for a cathode of a fuel cell, prepared according to the method of any one of claims 1 to 11.

13. A method for improving the catalytic performance of a copper-based catalyst for the cathode of a fuel cell, wherein, The copper-based catalyst is a 3,5-diamino-l,2,4-triazole copper complex powder, and the method comprises subjecting the 3,5-diamino-l,2,4-triazole copper complex powder to a pulsed laser treatment.

14. The method of claim 13, wherein, The catalytic performance includes 4-electron pathway selectivity.

15. The method of claim 13, wherein, The pulsed laser treatment increases the number of unsaturated coordinated copper center atoms in the 3,5-diamino-l,2,4-triazole copper complex.

16. Use of a copper-based catalyst for a cathode of a fuel cell, prepared according to the method of any one of claims 1 to 11, in an oxygen reduction reaction on the cathode side of a fuel cell.

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