Preparation method and application of composite PdS self-supporting electrode material

Abstract

The present invention discloses a preparation method and application of a composite PdS self-supporting electrode material, belonging to the technical field of electrocatalytic material preparation. This self-supporting electrode material utilizes sulfur (S) doping to precisely regulate the active sites of palladium (Pd), significantly improving the performance of the electrode material in the electrocatalytic production of peracetic acid. Specifically, the present invention successfully prepares a self-supporting electrode in which PdS nanoparticles are uniformly dispersed on a substrate by pre-sulfiding the Pd, followed by a simple calcination process. This unique structural design not only ensures the high performance of the catalyst but also gives the electrode material excellent stability and durability, enabling the efficient production of 1000-2000 ppm of peracetic acid, fully meeting the high-efficiency sterilization needs of daily and industrial fields, and exhibiting no significant performance degradation after 50 cycles. The simple and easily repeatable preparation steps provide a solid foundation for large-scale production and have broad application prospects and market potential.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic material preparation, and specifically relates to a preparation method and application of a composite PdS self-supporting electrode material. Background Art

[0002] Peracetic acid, a strong oxidant with potent oxidizing and bleaching properties, plays a vital role in the biopharmaceutical industry, food processing, and livestock and poultry farming. In terms of disinfection, peracetic acid is renowned for its highly effective bactericidal capabilities. It rapidly kills a wide range of microorganisms, including bacterial vegetative forms, mycobacteria, bacterial spores, fungi, algae, and viruses. Its bactericidal effect intensifies with increasing concentration and prolonged exposure. Furthermore, peracetic acid exhibits excellent stability, maintaining its disinfectant effectiveness over extended periods under certain conditions.

[0003] Currently, peracetic acid is primarily produced through the oxidation of acetic acid and acetaldehyde. These reactions, typically conducted under reduced pressure and high temperature, utilize sulfuric acid or other inorganic acids and ion exchange resins as catalysts. This cumbersome process and high energy costs hinder its widespread application and development.

[0004] In recent years, the rapid rise of electrocatalytic technology has become a focus of scientific research and industrial attention, with its environmentally friendly, cost-effective, and highly efficient characteristics attracting considerable attention. In the electrocatalytic process, the development of highly efficient and stable catalysts to optimize the production of peracetic acid and improve reaction selectivity and yield has become a key issue that needs to be addressed. This invention demonstrates a method for preparing a composite PdS self-supporting electrode material and its application. This catalyst precisely regulates the Pd active sites through S doping, achieving efficient electrocatalytic synthesis of peracetic acid, and has important practical application value and market prospects. Summary of the Invention

[0005] The present invention aims to provide a preparation and application of a composite PdS self-supporting electrode material. A composite PdS self-supporting electrode material is synthesized by a simple impregnation and roasting method. The advantages are simple operation, easy reproducibility, and efficient synthesis. In addition, the composite PdS self-supporting electrode material has excellent stability, durability, and electrocatalytic performance, and has good industrial prospects for application in the electrocatalytic production of peracetic acid.

[0006] The technical solution adopted in the present invention is as follows:

[0007] A method for preparing a composite PdS self-supporting electrode material comprises the following steps:

[0008] 1) Disperse the Pd source and S source in ethanol and homogenize them by ultrasonication;

[0009] 2) fully immersing the gas-repellent electrode support material in the ultrasonically dispersed solution of step 1) for 0.5-3 minutes per immersion, then drying the electrode support material in an oven to completely remove the ethanol; repeating the immersion and drying steps 10-25 times, ensuring that the electrode support material is evenly immersed in the solution each time;

[0010] 3) placing the electrode support material treated in step 2) in a tube furnace and calcining it in an inert gas Ar atmosphere to form PdS nanoparticles on the electrode support material, and then cooling it to room temperature to obtain a composite PdS self-supporting electrode.

[0011] Furthermore, the palladium salt in step 1) is one of palladium chloride PdCl2, chloropalladic acid H2[PdCl6], potassium chloropalladate K2PdCl4 and sodium chloropalladate Na2PdCl4, the S source is one of thiourea, sodium sulfide and sulfur powder, and the dispersion concentration of the S source in the ultrasonically dispersed solution in step 1) is 3-7 mmol / L, preferably 4-5 mmol / L.

[0012] Furthermore, in step 1), the molar ratio of the Pd source to the S source is 0.3-1:1, preferably 0.7-1:1.

[0013] Furthermore, the self-supporting electrode material needs to be selected from electrodes with good stability, gas repellency and certain deformation resistance, such as carbon felt, titanium felt, nickel felt, foam copper, foam iron, etc., preferably carbon felt.

[0014] Furthermore, in step 3), the calcination temperature is 300-700° C., preferably 400-500° C., and the calcination time is 1-5 h, preferably 3 h.

[0015] The present invention also provides an application of the composite PdS self-supporting electrode material in electrocatalytic production of peracetic acid, wherein the composite PdS self-supporting electrode material is used as a cathode working electrode; the electrocatalytic reaction process is carried out in a gas diffusion flow cell, comprising an anode chamber and a cathode chamber, the anode chamber and the cathode chamber being separated by a proton exchange membrane; the anode is a platinum mesh electrode, the cathode is the cathode working electrode, and the cathode divides the cathode chamber into two left and right chambers, the chamber closer to the proton exchange membrane being designated as a cathode liquid chamber, and the other chamber being a cathode air chamber, the cathode working electrode being located between the cathode liquid chamber and the cathode air chamber; the anode and cathode are respectively connected to a constant current meter via wires;

[0016] The anolyte is an H2SO4 aqueous solution, the cathode liquid chamber uses acetic acid as a reaction substrate, and the aqueous solution of the reaction substrate is used as the cathode electrolyte. Air or oxygen is introduced into the cathode air chamber, and a constant current meter is energized to perform an electrocatalytic reaction. The air or oxygen diffuses to the surface of the cathode working electrode and contacts the PdS nanoparticle catalyst component. Under the action of the catalyst, a reaction occurs at the cathode to generate peracetic acid.

[0017] Furthermore, the concentration of the H2SO4 aqueous solution is 0.05-1 mol / L, preferably 0.5 mol / L.

[0018] Furthermore, the device for the electrocatalytic reaction also includes an anode liquid storage tank, a cathode liquid storage tank, a circulation pump 1 and a circulation pump 2. When the electrocatalytic reaction is carried out, the circulation pump 1 is started to allow the cathode electrolyte to circulate between the cathode liquid storage tank and the cathode liquid cavity; at the same time, the circulation pump 2 is started to allow the anode electrolyte to circulate between the anode chamber and the anode liquid storage tank.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1) The raw materials are readily available and low-cost, and the electrocatalyst preparation steps are simple, making it easy to prepare in batches and scale up;

[0021] 2) The electrocatalytically produced peracetic acid has a high concentration and good stability;

[0022] 3) The preparation method and application of the composite PdS self-supporting electrode material prepared by the above-mentioned technology, wherein PdS is loaded on the self-supporting material substrate by simple infiltration and calcination. The present invention utilizes S element doping to regulate the active sites of Pd, greatly enhancing the concentration of peracetic acid produced by electrocatalysis. Secondly, the electrochemical production of peracetic acid without the generation of excessive waste liquid makes the production process more environmentally friendly and sustainable. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the SEM image of the catalyst on the surface of the material in Example 2;

[0024] Figure 2 This is a cyclic performance diagram of the electrocatalyst material performance test of Example 2 of the present invention;

[0025] Figure 3 This is a schematic diagram of the explosion structure of a gas diffusion flow cell according to an application embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0027] The carbon felt used in the embodiment of the present invention is of model KFD 2.5T, and its porosity is 94%. Such abundant porosity means that there can be sufficient gas-liquid contact, which is beneficial to the reaction.

[0028] Example 1: Preparation of a composite PdS self-supporting electrode material comprising the following steps (molar ratio Pd:S=0.5:1)

[0029] 1) Add 0.05 mmol of palladium chloride and 0.1 mmol of thiourea to 20 mL of ethanol, sonicate until uniformly distributed, and stir at room temperature for 15 min;

[0030] 2) 3×3cm 2 The carbon felt was immersed in the solution uniformly dispersed in step 1), and then placed in an oven for drying to completely remove the ethanol; the dipping and drying steps were repeated 20 times, with a single dipping time of 1 minute, each time ensuring that all electrode materials were evenly immersed in the solution.

[0031] 3) The self-supporting electrode treated in step 2) is placed in a tube furnace, and in an inert gas Ar atmosphere, the temperature is increased from room temperature to 400°C at a heating rate of 5°C / min, and then calcined at a constant temperature for 3 hours to form PdS nanoparticles. After the procedure is completed, the temperature is cooled to room temperature to obtain a self-supporting electrode composited with PdS.

[0032] Example 2: Preparation of a composite PdS self-supporting electrode material (molar ratio Pd:S=0.7:1)

[0033] The preparation steps of the electrode material in Example 2 were repeated in Example 1, with the only difference being that the amount of palladium chloride in step 1) was replaced with 0.07 mmol. Other conditions remained unchanged, and a self-supporting electrode of composite PdS was obtained.

[0034] Example 3: Preparation of a composite PdS self-supporting electrode material (molar ratio Pd:S=1:1)

[0035] The preparation steps of the electrode material in Example 3 were repeated in Example 1, with the only difference being that the amount of palladium chloride in step 1) was replaced with 0.1 mmol. Other conditions remained unchanged, and a self-supporting electrode of composite PdS was obtained.

[0036] Example 4: Preparation of a composite PdS self-supporting electrode material (molar ratio Pd:S=0.7:1)

[0037] The preparation steps of the electrode material of Example 4 are repeated in Example 2, with the only difference being that the calcination temperature in step 3) is replaced from 400°C to 300°C. Other conditions remain unchanged, and a self-supporting electrode of composite PdS can be obtained.

[0038] Example 5: Preparation of a composite PdS self-supporting electrode material (molar ratio Pd:S=0.7:1)

[0039] The preparation steps of the electrode material in Example 5 are the same as those in Example 2, with the only difference being that the calcination temperature in step 3) is replaced from 400° C. to 500° C., while other conditions remain unchanged, to obtain a self-supporting electrode of composite PdS.

[0040] Example 6: Preparation of a composite PdS self-supporting electrode material (molar ratio Pd:S=0.7:1)

[0041] The preparation steps of the electrode material of Example 6 are repeated in Example 2, with the only difference being that the calcination temperature in step 3) is replaced from 400°C to 600°C. Other conditions remain unchanged, and a self-supporting electrode of composite PdS can be obtained.

[0042] Example 7: Preparation of a composite PdS self-supporting electrode material (molar ratio Pd:S=0.7:1)

[0043] The preparation steps of the electrode material of Example 7 are repeated in Example 2, with the only difference being that the calcination temperature in step 3) is replaced from 400°C to 700°C. Other conditions remain unchanged, and a self-supporting electrode of composite PdS can be obtained.

[0044] Example 8: Preparation of a composite PdS self-supporting electrode material (molar ratio Pd:S=0.7:1)

[0045] The preparation steps of the electrode material of Example 8 are repeated in Example 2, with the only difference being that the calcination temperature in step 3) is replaced from 400°C to 800°C. Other conditions remain unchanged, and a self-supporting electrode of composite PdS can be obtained.

[0046] Example 9: Preparation of a composite PdS self-supporting electrode material (molar ratio Pd:S=0.7:1)

[0047] The preparation steps of the electrode material of Example 9 are repeated in Example 2, with the only difference being that the calcination temperature in step 3) is replaced from 400°C to 900°C. Other conditions remain unchanged, and a self-supporting electrode of composite PdS can be obtained.

[0048] Comparative Example 1: Preparation of a composite PdS self-supporting electrode material comprising the following steps (molar ratio Pd:P=0.7:1)

[0049] 1) Dissolve 0.07 mmol of palladium chloride and 0.1 mmol of sodium hypophosphite in 20 mL of ethanol, sonicate until the mixture is uniformly distributed, and stir at room temperature for 15 min.

[0050] 2) 3×3cm 2The carbon felt was immersed in the solution dispersed in step 1), and then placed in an oven for drying to completely remove the ethanol; the dipping and drying steps were repeated 20 times, with a single dipping time of 1 minute, each time ensuring that all the electrode materials were evenly immersed in the solution.

[0051] 3) The self-supporting electrode treated in step 2) is placed in a tube furnace, and in an inert gas Ar atmosphere, the temperature is increased from room temperature to 600°C at a heating rate of 5°C / min, and then calcined at a constant temperature for 3 hours to form PdP nanoparticles. After the procedure is completed, the temperature is cooled to room temperature to obtain a self-supporting electrode composited with PdP.

[0052] Comparative Example 2: Preparation of a composite PdS self-supporting electrode material includes the following steps

[0053] 1) Dissolve 0.07 mmol of palladium chloride and 0.1 mmol of urea in 20 mL of ethanol and sonicate until the mixture is evenly distributed. Stir at room temperature for 15 min.

[0054] 2) 3×3cm 2 The carbon felt was immersed in the solution dispersed in step 1), and then placed in an oven for drying to completely remove the ethanol; the dipping and drying steps were repeated 20 times, with a single dipping time of 1 minute, each time ensuring that all the electrode materials were evenly immersed in the solution.

[0055] 3) After the reaction is completed, the self-supporting electrode of step 2) is placed in a tube furnace, and in an inert gas atmosphere, the temperature is increased from room temperature to 600°C at a heating rate of 5°C / min, and then calcined at a constant temperature for 3 hours to form PdN nanoparticles. After the procedure is completed, the temperature is cooled to room temperature to obtain a self-supporting electrode with composite PdN.

[0056] Comparative Example 3: Preparation of a composite PdSe self-supporting electrode material comprising the following steps (molar ratio Pd:Se = 0.7:1)

[0057] 1) Disperse 0.07 mmol of palladium chloride and 0.1 mmol of Se powder in 20 mL of ethanol mixed solution by ultrasonication until uniform distribution, and stir at room temperature for 15 min.

[0058] 2) 3×3cm 2 The carbon felt was immersed in the solution dispersed in step 1), and then placed in an oven for drying to completely remove the ethanol; the dipping and drying steps were repeated 20 times, with a single dipping time of 1 minute, each time ensuring that all the electrode materials were evenly immersed in the solution.

[0059] 3) After the reaction is completed, the self-supporting electrode of step 2) is placed in a tube furnace, and in an inert gas atmosphere, the temperature is increased from room temperature to 600°C at a heating rate of 5°C / min, and then calcined at a constant temperature for 3 hours to form PdSe nanoparticles. After the procedure is completed, the temperature is cooled to room temperature to obtain a self-supporting electrode with composite PdSe.

[0060] Application Example 1: Experimental steps for testing the performance of a composite PdS self-supporting electrode material in electrocatalytic production of peracetic acid:

[0061] 1) The prepared composite PdS self-supporting electrode material is assembled as a cathode working electrode in a gas diffusion flow cell for testing.

[0062] 2) Commercial 3×3cm 2 A platinum mesh was used as the anode electrode, the anolyte was 1 L of a 0.5 mol / L H2SO4 aqueous solution, the catholyte was 1 L of a 5 mol / L CH3COOH aqueous solution, and the air flow rate into the cathode gas collector 3 was 20 mL / min. The cathode and anode electrodes were connected to the negative and positive poles of a constant current meter, respectively. The electrocatalytic reaction was carried out at 180 mA for 3 h, and then the concentration of peracetic acid produced in the catholyte was detected.

[0063] Its gas diffusion flow cell includes an anode chamber and a cathode chamber, which are separated by a proton exchange membrane. The anode uses a platinum mesh electrode, and the cathode uses the cathode working electrode. The cathode divides the cathode chamber into two left and right chambers. The chamber close to the proton exchange membrane is recorded as the cathode liquid chamber, and the other chamber is the cathode air chamber. The cathode working electrode is located between the cathode liquid chamber and the cathode air chamber; the anode and cathode are respectively connected to a constant current meter through wires.

[0064] The exploded structure diagram of the gas diffusion flow cell in this application is as follows Figure 3 As shown, the cathode and anode chambers are separated by a proton exchange membrane, including an end plate 1, a stainless steel conductive plate 2, a cathode gas collector 3, a cathode gas diffusion electrode 4, a cathode flow cell 5, a proton exchange membrane 6, an anode electrode 7, an anode flow cell 8 and an end plate 1 arranged from left to right. Fluororubber gaskets can be clamped between two adjacent module plates for sealing. All these modules can be assembled and fixed with bolts to form a stacked structure as a whole.

[0065] Among them, a hollow hole is set in the center of the anode electrode 7, an air inlet and an air outlet are respectively set at both ends of the cathode gas collector 3, and a liquid inlet and an outlet are respectively provided at both ends of the cathode flow pool 5 and the anode flow pool 8, which are connected to the cathode and anode liquid storage tanks through hoses to form a loop; a proton exchange membrane 6 is provided between the cathode flow pool 5 and the anode flow pool 8, and its area is larger than the area of ​​the hollow area in the center of the cathode and anode flow pools.

[0066] According to the test method of Application Example 1, the electrocatalysts prepared in Examples 1-9 and Comparative Examples 1-3 were tested respectively. The experimental results are shown in Table 1.

[0067] Table 1 Concentration of peracetic acid produced by different electrocatalyst tests

[0068] Catalyst Grouping Peracetic acid concentration (ppm) Example 1 1207 Example 2 1714 Example 3 1296 Example 4 1407 Example 5 1503 Example 6 1321 Example 7 1435 Example 8 1308 Example 9 1056 Comparative Example 1 118 Comparative Example 2 80 Comparative Example 3 640 Control 1: Carbon black 150 Control 2: Carbon nanotubes 136 Control 3: Pd / C catalyst 208

[0069] From the catalytic test results of the electrocatalysts of Examples 1-3 in Table 1, it can be seen that by changing the ratio of the Pd source to the S source to regulate the electronic effect of the S element on the Pd, the best effect of producing peracetic acid is achieved when the molar ratio is Pd:S=0.7:1. The SEM image of the catalyst on the surface of the material of Example 2 is shown in FIG. Figure 1 As shown, it is obvious that particles are loaded on the surface of the carbon felt fibers and are in a uniformly dispersed state; this highly distributed PdS nanoparticle helps to adsorb the reactants and desorb the product peracetic acid in time, and the high concentration of peracetic acid comes from this. In addition, the Pd loading was tested by ICP-MS. The actual Pd loading in the electrocatalyst prepared in Example 2 was 0.373% (the Pd loading in the electrocatalyst prepared in Example 1 was 0.233%, and the Pd loading in the electrocatalyst prepared in Example 3 was 0.56%); Examples 4-9 explored the effect of stability on its catalytic activity during calcination, and the activity was best when calcined at 400°C; in order to further explore the electronic regulation effect of different anions on Pd, different anion precursors (P, N and Se sources) were used for doping in Comparative Examples 1-3, and the performance test results were all better than those of the S source, highlighting the unique electronic regulation effect of the S element on Pd.

[0070] In addition, commercial carbon black, carbon nanotubes or Pd / C catalyst (Pd loading 1%) were used as control catalysts to further demonstrate the excellent performance of the composite PdS self-supporting electrode material in the electrocatalytic production of peracetic acid.

[0071] The durability and stability of the catalyst are important factors in evaluating its industrial application. The electrocatalyst material of Example 2 was subjected to a cyclic application experiment. After each experiment, the electrocatalytic reaction was carried out at 180 mA for 3 hours, and then the cathode and anode electrolytes were replaced with fresh ones, and then the next electrocatalyst application experiment was carried out. The cyclic application performance results of the electrocatalyst material performance test of Example 2 are shown in FIG. Figure 2 As shown, the composite PdS self-supporting electrode material was used in the electrocatalytic production of peracetic acid for 50 cycles, and its peracetic acid concentration did not show obvious attenuation, indicating its excellent durability and stability, and has certain industrial application and market potential for expansion.

Claims

1. A method for preparing a composite PdS self-supporting electrode material, characterized in that The following steps are involved: 1) Dispersing the palladium salt and a sulfur source in ethanol and homogenizing by ultrasonication, wherein the sulfur source is one of thiourea, sodium sulfide, and sulfur powder; 2) Fully immerse the gas-repellent electrode support material in the ultrasonically dispersed solution prepared in step 1) for 0.5-3 minutes per immersion. Then, dry the electrode support material in an oven to completely remove the ethanol. Repeat the immersion and drying steps 10-25 times, ensuring that the electrode support material is evenly immersed in the solution each time. 3) The electrode support material treated in step 2) is placed in a tube furnace and calcined in an inert gas Ar atmosphere to form PdS nanoparticles on the electrode support material. The temperature is then cooled to room temperature to obtain a composite PdS self-supporting electrode.

2. The method for preparing a composite PdS self-supporting electrode material according to claim 1, characterized in that The palladium salt in step 1) is one of palladium chloride PdCl2, chloropalladic acid H2[PdCl6], potassium chloropalladate K2PdCl4 and sodium chloropalladate Na2PdCl4, and the dispersion concentration of the S source in the ultrasonically dispersed solution in step 1) is 3-7 mmol / L.

3. The method for preparing a composite PdS self-supporting electrode material according to claim 2, characterized in that Step 1) The dispersion concentration of the S source in the ultrasonically dispersed solution is 4-5 mmol / L.

4. The method for preparing a composite PdS self-supporting electrode material according to claim 1, wherein In step 1), the molar ratio of the Pd source to the S source is 0.3-1:

1.

5. The method for preparing a composite PdS self-supporting electrode material according to claim 4, characterized in that In step 1), the molar ratio of the Pd source to the S source is 0.7-1:

1.

6. The method for preparing a composite PdS self-supporting electrode material according to claim 1, wherein The self-supporting electrode substrate materials used include carbon felt, nickel felt, titanium felt, copper foam or iron foam.

7. The method for preparing a composite PdS self-supporting electrode material according to claim 6, characterized in that The self-supporting electrode substrate material used includes carbon felt.

8. The method for preparing a composite PdS self-supporting electrode material according to claim 1, wherein In step 3), the calcination temperature is 300-700°C and the calcination time is 1-5 h.

9. The method for preparing a composite PdS self-supporting electrode material according to claim 8, characterized in that In step 3), the calcination temperature is 400-500°C and the calcination time is 3 h.

10. A composite PdS self-supporting electrode material prepared by the method according to any one of claims 1 to 9.

11. Use of the composite PdS self-supporting electrode material according to claim 10 in electrocatalytic production of peracetic acid.

12. The use according to claim 11, characterized in that The composite PdS self-supporting electrode material is used as a cathode working electrode; the electrocatalytic reaction process is carried out in a gas diffusion flow cell, which includes an anode chamber and a cathode chamber, the anode chamber and the cathode chamber are separated by a proton exchange membrane, the anode uses a platinum mesh electrode, the cathode uses the cathode working electrode, and the cathode divides the cathode chamber into two left and right chambers, the chamber close to the proton exchange membrane is recorded as the cathode liquid chamber, and the other chamber is the cathode air chamber, and the cathode working electrode is located between the cathode liquid chamber and the cathode air chamber; the anode and cathode are respectively connected to a constant current instrument through wires; The anolyte is an H2SO4 aqueous solution, the cathode liquid chamber uses acetic acid as a reaction substrate, and the aqueous solution of the reaction substrate is used as the cathode electrolyte. Air or oxygen is introduced into the cathode air chamber, and a constant current meter is energized to perform an electrocatalytic reaction. The air or oxygen diffuses to the surface of the cathode working electrode and contacts the PdS nanoparticle catalyst component. Under the action of the catalyst, a reaction occurs at the cathode to generate peracetic acid.

13. The use according to claim 12, characterized in that The concentration of H2SO4 aqueous solution is 0.05-1 mol / L.

14. The use according to claim 13, characterized in that The concentration of H2SO4 aqueous solution is 0.5 mol / L.

15. The use according to claim 12, characterized in that The device for the electrocatalytic reaction also includes an anode liquid storage tank, a cathode liquid storage tank, a circulation pump 1 and a circulation pump 2. When the electrocatalytic reaction is carried out, the circulation pump 1 is started to allow the cathode electrolyte to circulate between the cathode liquid storage tank and the cathode liquid cavity; at the same time, the circulation pump 2 is started to allow the anode electrolyte to circulate between the anode chamber and the anode liquid storage tank.

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