A copper-doped phosphide electrocatalytic material, a preparation method and application thereof

Abstract

This invention discloses a copper-doped phosphide electrocatalytic material, its preparation method, and its application, belonging to the field of catalyst technology. The preparation method involves dissolving Fe(NO3)3·9H2O, NH4F, and urea in water to obtain a mixed solution. This mixed solution is then transferred to a hydrothermal reactor, and carbon cloth is placed in the solution. Through a hydrothermal reaction, an iron precursor is loaded onto the surface of the carbon cloth. The iron precursor-loaded carbon cloth is then immersed in a CuCl2 solution. After immersion, the carbon cloth is removed and dried. The dried carbon cloth and NaH2PO2 are placed together in a tube furnace and calcined at high temperature under argon protection to obtain the copper-doped phosphide electrocatalytic material. The copper-doped iron phosphide electrode prepared by this invention achieves high ammonia yield, high ammonia Faradaic efficiency, and good cycle stability during the electrocatalytic reduction of nitrate. Furthermore, the copper-doped iron phosphide electrocatalytic material does not contain noble metal components, has a simple preparation process, and is suitable for industrial-scale production.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic materials technology, specifically to a copper-doped phosphide electrocatalytic material, its preparation method, and its application. Background Technology

[0002] Ammonia (NH3) is an important chemical raw material used in the production of fertilizers, explosives, plastics, and other products, playing a vital role in the national economy. Furthermore, as a zero-carbon fuel with a high hydrogen content, ammonia is also considered a promising energy carrier. Currently, large-scale industrial synthesis of ammonia uses the traditional Haber–Bosch process, which requires high temperature and pressure. The high-purity hydrogen used in this method is typically derived from carbon-containing fossil fuels, leading to high energy consumption and significant emissions of carbon dioxide greenhouse gases.

[0003] In recent years, the electrochemical synthesis of ammonia using water as a hydrogen source and nitrogen molecules as a nitrogen source at room temperature and pressure has been considered a green strategy for ammonia synthesis. However, the breaking of the nitrogen-nitrogen triple bond in nitrogen gas requires a huge amount of energy, and nitrogen has extremely low solubility in water. This results in low yields and Faraday efficiencies for ammonia synthesis via electrochemical nitrogen reduction (NRR), failing to meet the needs of practical production. Therefore, it is necessary to find more suitable nitrogen-containing molecules for ammonia synthesis. Compared with nitrogen molecules, nitrate ions have lower nitrogen-oxygen bond energies and high solubility in water, which is beneficial for electrocatalytic ammonia synthesis. Furthermore, nitrates are a typical nitrogen-containing pollutant, and their large-scale presence in water sources causes serious ecological and environmental problems. Therefore, considering both economic and environmental perspectives, nitrate reduction for ammonia production has significant application prospects.

[0004] Electrocatalytic reduction of nitrate to ammonia is a complex octet transfer process with numerous possible reaction intermediates. One of the current challenges in this field is the lack of electrocatalysts possessing high catalytic activity, high ammonia selectivity, and good stability. Furthermore, considering the cost of nitrate reduction to ammonia, an ideal electrocatalyst should have a simple synthesis method and be free of precious metals. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a copper-doped phosphide electrocatalytic material, its preparation method, and its application. This electrocatalytic material exhibits high ammonia selectivity, high yield, and good stability during the reduction of nitrate to ammonia.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing a copper-doped phosphide electrocatalytic material, the method comprising the following steps: S1, will , Urea was added to deionized water and stirred to obtain a mixed solution. The mixed solution was transferred to a hydrothermal reactor, and the pretreated carbon cloth was placed in the mixed solution. The carbon cloth surface was loaded with iron precursor through hydrothermal reaction. Then, the carbon cloth loaded with iron precursor was cleaned with distilled water and anhydrous ethanol to remove nitrate ions, iron ions and ammonium ions adsorbed on the carbon cloth surface. S2. Immerse the carbon cloth loaded with iron precursor in... After soaking in the solution, the carbon cloth is removed and washed with distilled water to remove the chloride and copper ions adsorbed on the surface of the carbon cloth. Then the carbon cloth is dried. S3, Place the dried carbon cloth and They are placed together in a tube furnace and calcined at high temperature under argon protection to obtain copper-doped phosphide electrocatalytic materials.

[0007] Preferably, in step S1, , The mass ratio of urea is 2-10:10:25; the concentration of iron ions is 1 / 35-1 / 7 mol / L.

[0008] Preferably, in step S1, the hydrothermal reaction temperature is 100℃-160℃, and the hydrothermal reaction time is 4.0-8.0h.

[0009] Preferably, in step S2, The concentration of the solution is 2.0-20.0 mM.

[0010] Preferably, in step S2, the immersion time of the carbon cloth loaded with iron precursor is 6.0-24.0 h.

[0011] Preferably, the drying in step S2 is carried out in an oven at a temperature of 60℃-80℃ for a time of 1-1.5 hours.

[0012] Preferably, in step S3, and The mass ratio is 2-10:5.

[0013] Preferably, in step S3, the temperature during high-temperature calcination is 300℃-500℃, and the calcination time is 3.0-6.0h.

[0014] Preferably, the copper-doped phosphide electrocatalytic material is prepared using the method described above.

[0015] Preferably, the copper-doped phosphide material is used as an electrocatalyst in the reduction of nitrate to produce ammonia.

[0016] The beneficial effects of this invention are: (1) The copper-doped iron phosphide electrocatalytic material disclosed in this invention does not contain precious metal components, and the preparation process is simple, the raw materials used are inexpensive, and no other organic solvents other than ethanol are used, which facilitates industrial production.

[0017] (2) The copper-doped iron phosphide electrocatalytic material prepared according to the technical solution of the present invention exhibits high ammonia yield, high Faraday efficiency and good cycle stability in the nitrate reduction reaction, and has broad market application prospects. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0019] Figure 1 The X-ray diffraction pattern of copper-doped iron phosphide prepared in Example 1; Figure 2 This is a scanning electron microscope image of the copper-doped iron phosphide prepared in Example 1; Figure 3 The graph shows the Faradaic efficiency and ammonia yield of copper-doped iron phosphide prepared in Example 1 under different voltages during nitrate reduction. Figure 4 The diagram shows the cycling performance of copper-doped iron phosphide prepared in Example 1 during nitrate reduction. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: A copper-doped phosphide electrocatalytic material and its preparation method are disclosed below: S1, 2.5 mmol 5.0 mmol 12.5 mmol of urea was dissolved in 35 mL of water and stirred for 20 minutes. The resulting solution was transferred to a 50 mL hydrothermal reactor. The pretreated carbon cloth was then placed in the hydrothermal reactor and hydrothermally reacted at 120 °C for 6 hours to grow an iron precursor on the surface of the carbon cloth. The product was washed multiple times with distilled water and anhydrous ethanol. S2. Immerse the iron precursor-loaded carbon cloth in 10.0 mm H₂O. After soaking in the solution for 12 hours, remove the carbon cloth, wash it several times with distilled water, and then put it in an oven at 60 degrees Celsius for 1.5 hours. S3. Place the carbon cloth obtained in S2 into a tube furnace, and select 0.5g of... Using it as a phosphorus source, it is calcined at 350°C for 5 hours under argon protection, and the resulting material is copper-doped iron phosphide.

[0022] like Figure 1 As shown in the X-ray diffraction pattern, in addition to the two obvious characteristic peaks of the carbon cloth substrate, the copper-doped iron phosphide (Cu-FeP) sample has peaks at 32.8, 35.8, and 48.4 degrees, which correspond to the (011), (120), and (211) crystal planes of FeP, respectively (PDF standard card: 39-0809). This indicates that copper doping has not changed the crystal structure of iron phosphide and that the copper-doped iron phosphide sample was successfully prepared. Figure 2 Scanning electron microscopy results show that the prepared nanoscale copper-doped iron phosphide sample is uniformly covered on the surface of the carbon cloth substrate.

[0023] The prepared copper-doped iron phosphide supported on carbon cloth was applied to the electrocatalytic reduction of nitrate to ammonia. The electrolytic cell used was an H-type three-electrode electrolytic cell, separated by a cation exchange membrane. The electrodes used were a counter electrode (platinum sheet electrode), a working electrode (copper-doped iron phosphide supported on carbon cloth), and a reference electrode (saturated calomel electrode). The electrolyte solution was 0.25 M. Solution and 2000ppm The solution was prepared using a CHI 760E workstation from Shanghai Chenhua. Chorometric galvanometry was used to determine the ammonia yield and Faradaic efficiency of copper-doped iron phosphide at different potentials. The electrolyte after the reaction was diluted within a measurable range, and the concentration of ammonia in the solution was determined using the indophenol blue colorimetric method. Figure 3 As shown, copper-doped iron phosphide exhibits high ammonia Faradaic efficiency at -0.55, -0.65, -0.75, -0.85, and -0.95 V (relative to the reversible hydrogen electrode), and the ammonia yield increases significantly with increasing negative potential. Specifically, at -0.95 V (relative to the reversible hydrogen electrode), the ammonia Faradaic efficiency is 92.53%, and the ammonia yield is as high as... The cycling performance of the copper-doped iron phosphide catalyst was tested by controlling a constant potential of -0.85V (relative to the reversible hydrogen electrode). Figure 4 As shown, in 10 consecutive nitrate reduction cycle tests, the copper-doped iron phosphide electrode consistently maintained good ammonia Faradaic efficiency and ammonia yield performance, indicating its excellent cycle stability. In summary, the copper-doped iron phosphide electrocatalytic material prepared by this invention exhibits excellent electrocatalytic performance for nitrate reduction to ammonia.

[0024] Example 2: A copper-doped phosphide electrocatalytic material and its preparation method are disclosed below: S1, 2.0 mmol 5.0 mmol 12.5 mmol of urea was dissolved in 35 mL of water and stirred for 20 minutes. The resulting solution was transferred to a 50 mL hydrothermal reactor. The pretreated carbon cloth was then placed in the hydrothermal reactor and hydrothermally reacted at 100 °C for 8 hours to grow an iron precursor on the surface of the carbon cloth. The product was then washed multiple times with distilled water and anhydrous ethanol. S2. Immerse the iron precursor-loaded carbon cloth in 5.0 mm of water. After soaking in the solution for 8 hours, remove the carbon cloth, wash it several times with distilled water, and then put it in an oven at 60 degrees Celsius for 1.5 hours. S3. Place the carbon cloth obtained in S2 into a tube furnace, and select 0.4g of... Using it as a phosphorus source, it is calcined at 300°C for 6 hours under argon protection, and the resulting material is copper-doped iron phosphide.

[0025] Example 3: A copper-doped phosphide electrocatalytic material and its preparation method are disclosed below: S1, 4.0 mmol 5.0 mmol 12.5 mmol of urea was dissolved in 35 mL of water and stirred for 20 minutes. The resulting solution was transferred to a 50 mL hydrothermal reactor. The pretreated carbon cloth was then placed in the hydrothermal reactor and hydrothermally reacted at 150 °C for 5 hours to grow an iron precursor on the surface of the carbon cloth. The product was then washed multiple times with distilled water and anhydrous ethanol. S2. Immerse the iron precursor-loaded carbon cloth in 15.0 mm H₂O. After soaking in the solution for 15 hours, remove the carbon cloth, wash it several times with distilled water, and then put it in an oven at 60 degrees Celsius for 1.5 hours. S3. Place the carbon cloth obtained in S2 into a tube furnace, and select 1.5g of... Using it as a phosphorus source, it is calcined at 450°C for 3 hours under argon protection, and the resulting material is copper-doped iron phosphide.

[0026] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a copper-doped phosphide electrocatalytic material, characterized in that, The preparation method includes the following steps: S1, will , Urea was added to deionized water and stirred to obtain a mixed solution with an iron ion concentration of 1 / 35-1 / 7 mol / L. The mixed solution was transferred to a hydrothermal reactor and the pretreated carbon cloth was placed in the mixed solution. The carbon cloth surface was loaded with iron precursor through hydrothermal reaction. Then, the carbon cloth loaded with iron precursor was cleaned with distilled water and anhydrous ethanol to remove nitrate ions, iron ions and ammonium ions adsorbed on the carbon cloth surface. S2. Immerse the carbon cloth loaded with iron precursor in... in solution, The concentration of the solution was 0.002-0.020 mol / L, and the soaking time of the iron precursor-loaded carbon cloth was 6.0-24.0 h. After soaking, the carbon cloth was taken out and washed with distilled water to remove the chloride and copper ions adsorbed on the surface of the carbon cloth. Then the carbon cloth was dried. S3, Place the dried carbon cloth and The materials are placed together in a tube furnace and calcined at high temperature under argon protection to obtain copper-doped phosphide electrocatalytic materials. and The mass ratio is 2-10:

5.

2. The preparation method according to claim 1, characterized in that: In step S1, , The mass ratio of urea is 2-10:10:

25.

3. The preparation method according to claim 1, characterized in that: In step S1, the hydrothermal reaction temperature is 100℃-160℃, and the hydrothermal reaction time is 4.0-8.0h.

4. The preparation method according to claim 1, characterized in that: In step S2, the drying is carried out in an oven at a temperature of 60℃-80℃ for 1-1.5 hours.

5. The preparation method according to claim 1, characterized in that: In step S3, the temperature during high-temperature calcination is 300℃-500℃, and the calcination time is 3.0-6.0h.

6. A copper-doped phosphide electrocatalytic material is prepared by the preparation method according to any one of claims 1-5.

7. The application of the copper-doped phosphide material as described in claim 6 as an electrocatalyst in the reduction of nitrate to prepare ammonia.

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