Method for improving electro-catalytic performance of precious metal-based material through electrochemical etching

Abstract

The invention discloses a method for improving the electro-catalytic performance of a precious metal-based material through electrochemical etching, and belongs to the technical field of electro-catalysis, and the method comprises the following steps: S1, preparing a Pt-Ni alloy as a precursor material through a chemical synthesis method, and carrying out cleaning and surface treatment on the prepared precursor material; s2, selecting a solvent and an electrolyte, and preparing an electrolyte solution; s3, fixing the precursor material on a working electrode, immersing the working electrode, a counter electrode and a reference electrode into the electrolyte, starting etching, monitoring and recording voltage and current changes in the etching process, gradually increasing the voltage after preliminary etching, paying attention to and monitoring the current changes and material surface changes, and keeping the voltage stable after the etching effect is achieved; according to the method, the electro-catalytic performance of the Pt-Ni alloy is improved through electrochemical etching and optimization of the surface appearance and composition of the Pt-Ni alloy, the optimal Pt: Ni ratio is found by synthesizing the Pt-Ni alloy with different ratios and performing electrochemical etching, and the optimal electro-catalytic activity and stability are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalysis, and specifically to a method for improving the electrocatalytic performance of noble metal-based materials through electrochemical etching. Background Art

[0002] At present, an effective method for improving the electrocatalytic performance of noble metal-based materials is electrochemical etching. Electrochemical etching (Electrochemical Machining, abbreviated as ECM) is a processing technology that uses the principle of electrochemical reaction to remove metal materials.

[0003] Noble metals such as platinum (Pt), palladium (Pd), and gold (Au) are widely used in the preparation of electrocatalysts due to their excellent electrocatalytic performance. However, these metal resources are scarce and expensive, so their utilization rate in the catalyst preparation process has become a key issue. In the prior art, the disadvantages of low noble metal utilization rate are mainly inaccurate control of particle size and morphology and poor dispersibility.

[0004] Moreover, insufficient electrocatalytic performance is an important problem faced by existing catalysts, which is mainly manifested in aspects such as low activity, high overpotential, and slow reaction kinetics, ultimately making the catalyst preparation process complex. For this reason, a method for improving the electrocatalytic performance of noble metal-based materials through electrochemical etching is proposed.

[0005] The above information disclosed in this background art is only used to increase the understanding of the background art of the present invention. Therefore, it may include prior art that is not known to those of ordinary skill in the art. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. For this reason, an object of the present invention is to propose a method for improving the electrocatalytic performance of noble metal-based materials through electrochemical etching.

[0007] To achieve the above object, the present invention provides the following technical solution:

[0008] A method for improving the electrocatalytic performance of noble metal-based materials through electrochemical etching, comprising the following steps:

[0009] S1. Using a Pt-Ni alloy as a precursor material, preparing it through a chemical synthesis method, and cleaning and surface-treating the prepared precursor material;

[0010] S2. Selecting a solvent and an electrolyte and preparing an electrolyte solution;

[0011] S3. Fix the precursor material on the working electrode, immerse the working electrode, counter electrode, and reference electrode in the electrolyte, start etching, monitor and record the voltage and current changes during the etching process. After preliminary etching, gradually increase the voltage while paying attention to monitoring the current change and the surface change of the material. Keep the voltage stable after achieving the etching effect.

[0012] S4. Take out the working electrode, clean the etched material with deionized water and alcohol solvents to remove the residual electrolyte and by-products on the surface, and perform vacuum drying.

[0013] S5. Use weak acid to remove the oxide layer, introduce a carbon coating layer, form a uniform carbon coating layer on the material surface by hydrothermal method, introduce functional molecules, and fix the functional molecules on the material surface by chemical adsorption.

[0014] S6. Introduce functional ions onto the Pt surface by ion exchange, and treat the material with a cross-linking agent to enhance the stability of the Pt-ionomer interface.

[0015] As a further optimized solution of the present invention, in S1, the specific steps for preparing the Pt-Ni alloy by chemical synthesis method are as follows:

[0016] Mix the dissolved H2PtC l6 and Ni(NO3)2 solutions in accordance with the Pt:Ni ratio, add polyvinylpyrrolidone PVP during the mixing process and stir, add the reducing agent solution to the mixed precursor solution, and control the addition rate of the reducing agent.

[0017] After the addition of the reducing agent, a color change in the reaction mixture indicates that metal ions are being reduced to metal nanoparticles, and continue to stir the reaction mixture.

[0018] After stopping stirring, Pt-Ni alloy nanoparticles are formed in the reaction mixture. Use centrifugal separation to separate the synthesized Pt-Ni alloy nanoparticles from the reaction mixture, wash the nanoparticles with deionized water and alcohol solvents multiple times to remove unreacted reagents and by-products, and perform freeze-drying treatment on the washed Pt-Ni alloy nanoparticles.

[0019] As a further optimized solution of the present invention, in step S2, the specific steps for preparing the electrolyte are as follows:

[0020] Prepare 36-38% concentrated hydrochloric acid, use distilled water as a diluent, and use a volumetric flask to prepare the electrolyte.

[0021] Add the concentrated hydrochloric acid to deionized water and stir the solution with a magnetic stirrer.

[0022] Use a pH meter to determine the accurate concentration of hydrochloric acid. If the concentration is too high, continue to add deionized water for dilution. If the concentration is too low, add concentrated hydrochloric acid for adjustment;

[0023] Operate at 20 - 25 °C. After the solution is diluted and stirred evenly, cool it to 25 - 30 °C. Finally, adjust the pH value using dilute nitric acid.

[0024] As a further optimized scheme of the present invention, in step S3, the initial voltage is set to 1 - 2 V, the etching time is 30 - 60 min, and the voltage is increased by 0.5 V each time.

[0025] As a further optimized scheme of the present invention, in step S4, the cleaning time for both ultrasonic cleaning and alcohol solvent cleaning is 5 - 10 min.

[0026] As a further optimized scheme of the present invention, the reaction time is 3 - 5 h, and the reaction temperature is within 25 °C.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] The present invention optimizes the surface morphology and composition of the Pt - Ni alloy through electrochemical etching, thereby improving its electrocatalytic performance. By synthesizing Pt - Ni alloys with different ratios and performing electrochemical etching, the optimal Pt:Ni ratio is found to achieve the best electrocatalytic activity and stability.

[0029] The present invention forms a uniform carbon coating layer on the material surface through the hydrothermal method, enhancing the electrochemical stability and conductivity of the material, while protecting the metal core from corrosion. And functional molecules are fixed on the material surface through chemical adsorption to further regulate the surface properties of the material and enhance its electrocatalytic performance.

[0030] The above summary is only for the purpose of the specification and is not intended to be limiting in any way. In addition to the above - described illustrative aspects, embodiments, and features, further aspects, embodiments, and features of the present invention will be readily apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flowchart of the method for improving the electrocatalytic performance of noble - metal - based materials through electrochemical etching according to the present invention;

[0032] Figure 2 It is a flowchart of controlling the electrochemical etching process in the present invention;

[0033] Figure 3 It is a flowchart of the surface modification method in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] Please refer to Figures 1 - 3 , a method for improving the electrocatalytic performance of noble metal-based materials by electrochemical etching, comprising the following steps:

[0036] S1. Using a Pt-Ni alloy or a Pt-Ni core-shell structure as a precursor material, preparing it by chemical synthesis, and cleaning and surface-treating the prepared precursor material;

[0037] The specific steps for preparing the Pt-Ni alloy by chemical synthesis:

[0038] Mix the dissolved H2PtC l6 and Ni(NO3)2 solutions in the required Pt:Ni ratio. During the mixing process, add polyvinylpyrrolidone PVP and stir. Slowly add the reducing agent solution to the mixed precursor solution, and control the addition rate of the reducing agent to prevent the reaction from being too violent.

[0039] After adding the reducing agent, when the color of the reaction mixture changes, it indicates that metal ions are being reduced to metal nanoparticles. Continue to stir the reaction mixture and keep the reaction temperature within 25°C;

[0040] Stop stirring after 3 - 5 h, and Pt-Ni alloy nanoparticles in the reaction mixture are formed.

[0041] Use centrifugal separation technology to separate the synthesized Pt-Ni alloy nanoparticles from the reaction mixture, and wash the nanoparticles with deionized water and alcohol solvents multiple times to remove unreacted reagents and by-products.

[0042] Perform freeze-drying treatment on the washed Pt-Ni alloy nanoparticles.

[0043] Wash the synthesized precursor material with deionized water to remove adsorbed impurities and unreacted raw materials on the surface. Use nitric acid to remove the oxide layer on the surface.

[0044] S2. Select a solvent and an electrolyte and prepare an electrolyte solution;

[0045] The specific steps for preparing the electrolyte solution are as follows:

[0046] Prepare 36 - 38% concentrated hydrochloric acid, use distilled water as a diluent, and prepare a volumetric flask for preparing the electrolyte solution;

[0047] Calculate the volume of hydrochloric acid required, add concentrated hydrochloric acid to deionized water, and stir the solution using a magnetic stirrer;

[0048] Use a pH meter to determine the exact concentration of hydrochloric acid. If the concentration is too high, continue to add deionized water for dilution; if the concentration is too low, add an appropriate amount of concentrated hydrochloric acid for adjustment;

[0049] Operate at room temperature. After the solution is diluted and stirred evenly, let it cool to room temperature. Finally, adjust the pH using dilute nitric acid.

[0050] S3. Fix the precursor material on the working electrode, immerse the working electrode, counter electrode, and reference electrode in the electrolyte, start etching, monitor and record the voltage and current changes during the etching process. After preliminary etching, gradually increase the voltage while paying attention to monitoring the current changes and the surface changes of the material. Keep the voltage stable after achieving the etching effect;

[0051] Specifically, for the etching time, adopt a multi-step etching method. The first stage removes the surface inactive layer, and the second stage performs fine etching. Set different times for each stage and the temperature of the electrolyte is between 50 °C.

[0052] Optimize the ratio of Pt to other metals. The specific steps are as follows:

[0053] Select Ni as the metal combined with Pt, and set the Pt:Ni ratios of 90:10, 80:20, 70:30, and 60:40.

[0054] Use the chemical reduction method to synthesize Pt-Ni alloys with different ratios, making the synthesis conditions of the alloys consistent, and compare the alloy properties under different ratios.

[0055] Perform electrochemical etching on the synthesized Pt-Ni alloys with different ratios to form a specific morphological structure. Use the same electrochemical etching parameters to separately evaluate the influence of ratio changes on the alloy phase.

[0056] Use cyclic voltammetry (CV) to evaluate the electrocatalytic activity of alloys with different ratios.

[0057] Analyze the electrocatalytic performance data under different Pt:Ni ratios to determine which ratio of the alloy exhibits the highest catalytic activity.

[0058] According to the performance evaluation results, select the optimal Pt:Ni ratio for optimization and perform more refined ratio adjustment near the optimal ratio.

[0059] S4. Take out the working electrode, wash the etched material with deionized water and alcohol solvents to remove the residual electrolyte and by-products on the surface, and perform vacuum drying;

[0060] Specifically, take out the etched working electrode from the electrolyte, rinse the electrode surface with deionized water, immerse the working electrode in a beaker filled with deionized water for cleaning, replace the deionized water, repeat the ultrasonic cleaning step 1-2 times, immerse the working electrode in a beaker filled with an alcohol solvent for cleaning, replace the alcohol solvent, and repeat the ultrasonic cleaning step 1-2 times. Take out the cleaned working electrode from the alcohol solvent, and gently blot the solvent on the electrode surface with a clean filter paper. Place the electrode in a vacuum drying oven, set the temperature to 50 °C, and the time to 1-2 h to remove the residual solvent and moisture on the electrode.

[0061] S5. Use a weak acid to remove the oxide layer, introduce a carbon coating layer, form a uniform carbon coating layer on the material surface by hydrothermal method, introduce functional molecules, and fix the functional molecules on the material surface by chemisorption.

[0062] Specifically, use citric acid as a precursor to form a carbon coating layer. The specific steps are as follows:

[0063] Weigh citric acid and put it into a beaker, add deionized water, and stir with a magnetic stirrer until the citric acid is completely dissolved. Accelerate the dissolution process by heating.

[0064] Continue to add deionized water to adjust the solution concentration to the desired value. Add sodium dodecyl sulfate, add the surfactant to the citric acid solution, and continue to stir until evenly mixed.

[0065] Use dilute nitric acid to adjust the pH value of the citric acid solution, add the cleaned and dried Pt-Ni alloy nanoparticles to the prepared citric acid solution, and stir well with a magnetic stirrer to make the nanoparticles evenly dispersed in the solution.

[0066] Steps for fixing functional molecules by chemisorption:

[0067] Material and equipment preparation: Pt-Ni alloy nanoparticles, thiol (e.g., mercaptopropionic acid (MPA) or mercaptoethanol), absolute ethanol, vacuum drying oven, glass container or beaker, magnetic stirrer, ultrasonic cleaner, deionized water or distilled water, filter paper or suction filtration device.

[0068] Specific steps: Weigh 1-5 mmol of thiol, dissolve the thiol in absolute ethanol to prepare a 0.1 M solution, and stir the solution with a magnetic stirrer until the thiol is completely dissolved.

[0069] Rinse the Pt-Ni alloy nanoparticles with deionized water multiple times to remove impurities, and then clean them again with dilute hydrochloric acid, and then thoroughly rinse with deionized water.

[0070] Transfer the cleaned Pt-Ni alloy nanoparticles into a glass container containing a thiol solution and gently stir using a magnetic stirrer to evenly distribute the nanoparticles in the solution. Place the container in a room temperature environment and soak for 12 h.

[0071] After the soaking is completed, use a suction filtration device to separate the nanoparticles from the solution. Rinse the nanoparticles with anhydrous ethanol multiple times to remove unadsorbed thiol molecules, and use an ultrasonic cleaner to assist in the cleaning.

[0072] Place the cleaned nanoparticles in a vacuum drying oven and dry at a temperature of 40 - 60 °C to remove the residual ethanol.

[0073] Use FTIR and XPS to confirm whether the thiol molecules are successfully adsorbed on the surface of the Pt-Ni alloy nanoparticles, and evaluate the performance of the modified nanoparticles through electrochemical tests.

[0074] S6. Introduce functional ions onto the Pt surface through an ion exchange process and treat the material with a crosslinking agent to enhance the stability of the Pt and ionomer interface.

[0075] In summary, the present invention optimizes the surface morphology and composition of the Pt-Ni alloy through electrochemical etching, thereby improving its electrocatalytic performance. By synthesizing Pt-Ni alloys with different ratios and performing electrochemical etching, the optimal Pt:Ni ratio is found to achieve the best electrocatalytic activity and stability.

[0076] The present invention uses deionized water and alcohol solvents to clean the etched material, which can effectively remove the residual electrolyte and by-products on the surface, ensure the cleanliness of the material surface, and provide a good basis for subsequent processing steps. And use weak acid to remove the oxide layer on the material surface to further expose the catalytically active metal surface.

[0077] The present invention forms a uniform carbon coating layer on the material surface through a hydrothermal method to enhance the electrochemical stability and conductivity of the material, while protecting the metal core from corrosion. And fix functional molecules on the material surface through chemisorption to further regulate the surface properties of the material and enhance its electrocatalytic performance.

[0078] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0079] In the drawings of the disclosed embodiments of the present invention, only the structures related to the disclosed embodiments are involved. For other structures, reference can be made to the general design. Without conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

[0080] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for improving the electrocatalytic performance of noble metal-based materials through electrochemical etching, characterized in that, It includes the following steps: S1. Use Pt-Ni alloy as the precursor material, prepare it by chemical synthesis method, and clean and surface-treat the prepared precursor material; S2. Select a solvent and an electrolyte and prepare an electrolyte solution; S3. Fix the precursor material on the working electrode, immerse the working electrode, counter electrode and reference electrode in the electrolyte solution, start etching, monitor and record the voltage and current changes during the etching process. After preliminary etching, gradually increase the voltage while paying attention to monitoring the current change and the material surface change. After achieving the etching effect, keep the voltage stable; S4. Take out the working electrode, clean the etched material with deionized water and alcohol solvents to remove the residual electrolyte solution and by-products on the surface, and perform vacuum drying; S5. Use a weak acid to remove the oxide layer, introduce a carbon coating layer, form a uniform carbon coating layer on the material surface by hydrothermal method, introduce functional molecules, and fix the functional molecules on the material surface by chemical adsorption; S6. Introduce functional ions onto the Pt surface by ion exchange, and treat the material with a crosslinking agent to enhance the stability of the Pt-ionomer interface.

2. A method for improving the electrocatalytic performance of noble metal-based materials by electrochemical etching according to claim 1, characterized in that: In S1, the specific steps for preparing Pt-Ni alloy by chemical synthesis method are: Dissolve the prepared H2PtC l6 and Ni(NO3)2 solution are mixed according to the Pt:Ni ratio. During the mixing process, polyvinylpyrrolidone PVP is added and stirred. Then, the reducing agent solution is added to the mixed precursor solution, and the addition rate of the reducing agent is controlled; After adding the reducing agent, a color change in the reaction mixture indicates that metal ions are being reduced to metal nanoparticles, and continue to stir the reaction mixture; After stopping stirring, Pt-Ni alloy nanoparticles in the reaction mixture are formed. Use centrifugal separation to separate the synthesized Pt-Ni alloy nanoparticles from the reaction mixture, wash the nanoparticles with deionized water and alcohol solvents multiple times to remove the unreacted reagents and by-products, and perform freeze-drying treatment on the washed Pt-Ni alloy nanoparticles.

3. A method for improving the electrocatalytic performance of noble metal-based materials by electrochemical etching according to claim 1, characterized in that: In step S2, the specific steps for preparing the electrolyte solution are: Prepare 36-38% concentrated hydrochloric acid, use distilled water as the diluent, and use a volumetric flask to prepare the electrolyte solution; Add the concentrated hydrochloric acid to deionized water and stir the solution with a magnetic stirrer; Use a pH meter to determine the accurate concentration of hydrochloric acid. If the concentration is too high, continue to add deionized water for dilution. If the concentration is too low, add concentrated hydrochloric acid for adjustment; Operate at 20-25 °C. After the solution is diluted and stirred evenly, cool it to 25-30 °C. Finally, adjust the pH value with dilute nitric acid.

4. A method for improving the electrocatalytic performance of noble metal-based materials by electrochemical etching according to claim 1, characterized in that: In step S3, the initial voltage is set to 1-2 V, the etching time is 30-60 min, and the voltage is increased by 0.5 V each time.

5. A method for improving the electrocatalytic performance of noble metal-based materials by electrochemical etching according to claim 1, characterized in that: In step S4, the cleaning time for both ultrasonic cleaning and alcohol solvents is 5-10 min.

6. A method for improving the electrocatalytic performance of noble metal-based materials by electrochemical etching according to claim 2, characterized in that: The reaction time is 3-5 h and the reaction temperature is 25 °C.

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