Copper-based phosphide catalyst, electro-deposition preparation method thereof and application of copper-based phosphide catalyst in nitrate reduction synthesis ammonia reaction

Abstract

The invention discloses a copper-based phosphide catalyst, an electro-deposition preparation method thereof and application of the copper-based phosphide catalyst in a nitrate reduction synthesis ammonia reaction, and belongs to the technical field of catalysis and sustainable development of energy. The catalyst is obtained by depositing a copper tin-copper phosphorus compound on a foamed nickel substrate by adopting an electro-deposition technology, the copper tin-copper phosphorus compound is formed by compounding two phases of CuSn alloy and Cu3P, and the molar ratio of CuSn to Cu3P is 1: (4.5-7.5); the copper tin-copper phosphorus compound is in a pine needle shape. According to the catalyst, through the synergistic effect of three elements of Cu, Sn and P, the nitrate adsorption / activation capacity and proton transfer kinetics are optimized, and the selectivity and reaction rate of NO3RR are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sustainable development of catalysis and energy, and in particular to a copper-based phosphide catalyst, an electrodeposition preparation method thereof, and an application thereof in a nitrate reduction ammonia synthesis reaction. Background Art

[0002] Ammonia (NH3) is a crucial industrial raw material. Global NH3 production exceeded 200 million tons in 2024, with approximately 80% used in fertilizer production. This has significantly contributed to increasing global food production and feeding 7 billion people. NH3 also plays a crucial role in pharmaceuticals, dyes, explosives, and other fields. A key advantage of NH3 is its high hydrogen reserve. It can be synthesized from H2 and N2 in the air. Its high hydrogen content allows it to be liquefied under pressure at room temperature. While low-density hydrogen is difficult to store and transport, liquefied ammonia has a low combustion rate and low flammability, making it suitable for long-distance transportation. Therefore, NH3 is likely to develop into a renewable energy source, such as fuel cells. In the early 20th century, the industrial process for artificial nitrogen fixation was initially established. Bosch subsequently improved the high-pressure NH3 synthesis technology and employed iron-based materials as catalysts to facilitate its industrial production, resulting in the Haber-Bosch process, which is still used today. Since then, the chemical industry has developed rapidly, and the technology for synthesizing NH3 has become relatively extensive and mature. However, traditional NH3 synthesis processes are demanding, waste significant amounts of fossil energy, release large amounts of greenhouse gases, and have relatively low NH3 conversion rates. In recent years, the growing maturity of water electrolysis (H2O) technology has made it possible to replace the direct use of fossil energy to provide hydrogen. Furthermore, renewable energy sources such as solar energy can be used to convert this energy into electricity, which is then fed into the water electrolysis process. This technology significantly reduces fossil energy consumption and greenhouse gas emissions, meeting the requirements of green production. Therefore, the nitrate reduction method for synthesizing ammonia, which can be carried out under conventional conditions using renewable electricity for green and sustainable ammonia synthesis, has gradually gained attention.

[0003] Currently, there are two main ways to produce NH3 electrochemically, including N2 reduction reaction (NRR) and nitrate Reduction reaction (NO3RR). A three-electrode system is constructed for electrochemical catalysis. In the three-electrode system, a metal platinum (Pt) sheet is used as a counter electrode, Ag / AgCl is used as a reference electrode, and the catalyst is coated on the electrode surface with a pipette or a self-supporting catalyst is directly used as a working electrode. In order to prevent the product NH3 from moving to the anode surface for oxidation reaction and resulting in a decrease in yield, the electrochemical reduction operation is generally carried out in a double electrolytic cell, that is, an H-type electrolytic cell. The working electrode and the reference electrode will be inserted in the electrolyte of the cathode chamber, while the counter electrode is located in the electrolyte of the anode chamber. The electrodes can be distinguished by their colors. The two electrolytic cells of the H-type electrolytic cell are separated by a proton membrane. The two use N2 in the air and NO3 in nitrate respectively. - As a nitrogen source, hydrogen ions (H + ) or H2O molecules as hydrogen source, and after electrochemical reduction, the product NH3 is obtained. After NH3 is consumed, N2 and NO3 are generated. - The raw materials for producing NH3 can be used again for electrochemical production of NH3, thus realizing an environmentally friendly nitrogen cycle.

[0004] This green and environmentally friendly nitrogen cycle avoids harsh conditions such as high temperature and high pressure, and because the required electricity can be produced through renewable energy, it truly achieves pollution-free production of NH3 and realizes the sustainable development of the energy cycle, so it has received widespread attention. However, the dissociation energy required for NRR is very high, and the solubility of N2 in water is very low at room temperature and pressure, making it difficult to enrich on the electrode surface for reduction reaction. Even if it is partially soluble in water, the applied voltage makes it easier to electrolyze water to produce H2. NO3RR only needs to consider the highly selective synthesis of NH3 and the suppression of HER side reactions. Because NO3RR may produce other by-products, such as NO2 - , hydrazine hydrate (N2H4), etc. Secondly, when operating at a negative electrocatalytic potential, the efficiency of the catalyst in synthesizing NH3 is limited by the HER. Therefore, how to improve the selectivity of NH3 production while suppressing the HER side reaction is also a research focus of NO3RR.

[0005] In summary, it is very necessary to find a simple and effective method to synthesize efficient, highly selective and low-cost NO3RR catalysts. Summary of the Invention

[0006] In order to solve the bottleneck problems of low target product selectivity and slow reaction rate in the existing NO3RR, the purpose of the present invention is to provide a copper-based phosphide catalyst and its electrodeposition preparation method and application in the nitrate reduction synthesis reaction of ammonia. By adjusting and optimizing the process parameters of the electrochemical deposition technology, a CuSn / Cu3P@NF nanocomposite catalyst is obtained and used as a catalyst in the nitrate reduction synthesis reaction of ammonia, with excellent performance of high efficiency, high selectivity and low cost.

[0007] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0008] A copper-based phosphide catalyst is a nanocomposite material (CuSn / Cu3P@NF) obtained by taking nickel foam as a substrate and depositing a copper-tin-copper-phosphorus complex on the substrate.

[0009] Furthermore, the nanocomposite material is represented as CuSn / Cu3P@NF, wherein CuSn / Cu3P is a copper-tin-copper-phosphorus composite, which is composed of a CuSn alloy and Cu3P two-phase composite, and NF is a foam nickel substrate; the copper-tin-copper-phosphorus composite has a pine needle-like morphology and is evenly distributed on the foam nickel substrate.

[0010] Furthermore, the loading amount of the copper-tin-copper-phosphorus composite on the nickel foam substrate is 0.33 mg-5.28 mg / cm 2 ; The molar ratio of CuSn to Cu3P in the copper-tin-copper-phosphorus complex is 1:(4.5~7.5).

[0011] Furthermore, the electrodeposition preparation method of the copper-based phosphide catalyst comprises the following steps:

[0012] S1. Prepare a nickel foam sheet of a desired size and clean it; the cleaning process is to ultrasonically clean the nickel foam sheet using acetone, ethanol, and hydrochloric acid in sequence;

[0013] S2. Prepare a sedimentation solution, the sedimentation solution composition is: CuCl2·2H2O 13.6-14.5g / L, SnCl2·2H2O 7.60-8.25g / L, NaH2PO4 0.9-1.5g / L, and the balance is water;

[0014] S3. Connecting the nickel foam sheet treated in step S1 and the deposition solution obtained in step S2 to an electrochemical workstation, and obtaining a copper-tin-copper-phosphorus complex on the surface of the nickel foam sheet by electrochemical deposition, that is, obtaining the copper-based phosphide catalyst.

[0015] Furthermore, in step S1, the process of ultrasonic cleaning with acetone is as follows: adding acetone until the nickel foam sheet is submerged, ultrasonicating for 30 minutes, and then repeatedly cleaning with deionized water for 3-5 times after the ultrasonication is completed;

[0016] Furthermore, in step S1, the process of ultrasonic cleaning with ethanol is as follows: adding ethanol to immerse the nickel foam sheet, ultrasonicating for 30 minutes, and then repeatedly washing with deionized water 3-5 times after the ultrasonication is completed;

[0017] Furthermore, in step S1, the process of ultrasonic cleaning with hydrochloric acid is as follows: diluting 1 mol / L hydrochloric acid (HCl) with a dilution ratio of 1:10 (the volume ratio of 1 mol / L hydrochloric acid to added water is 1:10); adding the diluted hydrochloric acid to immerse the foam nickel sheet, ultrasonicating for 5 minutes, and repeatedly washing with deionized water 3-5 times after the ultrasonication is completed; soaking the cleaned foam nickel sheet in deionized water for storage.

[0018] Furthermore, in step S2, the preparation process of the deposition liquid is as follows: copper chloride dihydrate (CuCl2·2H2O) is added to water to prepare a copper chloride dihydrate solution, and then tin chloride dihydrate (SnCl2·2H2O) and sodium dihydrogen phosphate (NaH2PO4) are added in sequence according to the proportion of each solute in the deposition liquid, and the resulting mixture is allowed to stand until all the solutes are dissolved (no obvious particles or crystals are left), thereby obtaining the deposition liquid.

[0019] Furthermore, in the electrochemical deposition process of step S3, a three-electrode electrolytic cell is used, the deposition solution obtained in step S2 is used as the electrolyte, the nickel foam sheet is used as the working electrode, the graphite rod is used as the auxiliary electrode, and the Ag / AgCl electrode is used as the reference electrode for electrochemical deposition.

[0020] Furthermore, the electrochemical deposition in step S3 is carried out in a constant current mode with a current density of 10-40 mA / cm 2 The deposition time is 100-400 seconds. After the deposition is completed, the sample is dried in a vacuum drying oven for 3-10 hours to obtain a nanocomposite material (Cu x Sn y / Cu3P@NF), which is the copper-based phosphide catalyst.

[0021] Furthermore, the copper-based phosphide catalyst is applied to a reaction of synthesizing ammonia by reducing nitrate. During the application process, the nitrate to be reduced is first prepared into a nitrate solution, and potassium hydroxide is added to the nitrate solution to prepare an electrolyte. A three-electrode electrochemical system is constructed using the copper-based phosphide catalyst as a working electrode, Ag / AgCl as a reference electrode, and a platinum sheet electrode as a counter electrode. The entire electrochemical system is placed in an H-type electrolytic cell, and ammonia is synthesized by electrocatalytic nitrate reduction. In the electrolyte, the potassium hydroxide concentration is 0.1-1 mol / / L, and the nitrate concentration is 0.05-1.0 mol / / L.

[0022] The advantages and beneficial effects of the present invention are as follows:

[0023] 1. The present invention adopts a simple and easy-to-operate, green and pollution-free electrodeposition method without the addition of precious metals. It can be completed at room temperature and has the advantages of a fast and efficient synthesis process and simple operation. In addition, the incorporation of P significantly changes the microscopic morphology of the copper-tin alloy presenting a spherical structure, transforming it into a pine needle-like structure, thereby increasing its reaction area and the number of reaction cycles and duration.

[0024] 2. X-ray diffraction (XRD) analysis of the phase of the electrodeposition sample revealed that the sample was formed by depositing a copper-tin-copper-phosphorus complex onto nickel foam. The copper-tin-copper-phosphorus complex is composed of a CuSn alloy and Cu3P, with a molar ratio of CuSn to Cu3P of 1:(4.5-7.5). X-ray photoelectron spectroscopy (XPS) results indicate that the introduction of P alters the electronic structure of Cu and Sn. This change in electronic structure optimizes the catalyst's adsorption of reactants and intermediates, potentially enhancing its catalytic activity.

[0025] 3. The linear sweep voltammetry curves show that the current density of the electrolytic cell with potassium nitrate added is higher than that without potassium nitrate, demonstrating the excellent catalytic performance of the designed CuSn / Cu3P@NF nanocomposite catalyst in the electrochemical catalytic test of nitrate-to-ammonia synthesis. To investigate the source of nitrogen in the NH3 product of the NO3RR process and evaluate the accuracy of NH3 detection using ultraviolet spectrophotometry (UV-Vis), 1H nuclear magnetic resonance spectroscopy (1H NMR) was used for qualitative and quantitative verification. The results confirmed that the nitrogen in the NH3 product indeed originates solely from nitrate, not from other sources.

[0026] 4. Both UV-Vis and 1H NMR demonstrate that at room temperature, when the molar ratio of CuSn to Cu3P in the copper-tin-copper-phosphorus complex is 1:(4.5-7.5), the CuSn / Cu3P@NF nanocomposite catalyst exhibits much higher NH3 yield and Faraday efficiency than existing Cu@NF and CuSn / SnO2@NF. Furthermore, the catalyst activity of the present invention is also very outstanding compared to similar catalysts. Furthermore, the removal test shows that CuSn / Cu3P@NF can reduce the nitrogen concentration in industrial wastewater from an initial value of 1200 μg·mL to 100 μg·mL within 10 hours. -1 The high concentration was reduced to below the contamination limit of 11.30 μg·mL in drinking water stipulated by the World Health Organization. -1 .

[0027] In summary, the present invention uses a novel, simple, and efficient method to synthesize the CuSn / Cu3P@NF nanocomposite catalyst. The synthesized catalyst is applied to the nitrate ammonia production reaction, which can achieve very good catalytic activity. The synthesis method is simple and has relatively high NO3RR activity. The nitrogen source for the synthesized ammonia comes from the nitrogen in the nitrate. This catalyst provides a new idea for the synthesis of NO3RR catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Scanning electron microscope images of the catalysts in Comparative Examples 1-2; wherein: (a) Cu@NF catalyst in Comparative Example 1; (b) CuSn / SnO2@NF nanocomposite catalyst in Comparative Example 2.

[0029] Figure 2 This is a scanning electron microscope image of the CuSn / Cu3P@NF nanocomposite catalyst in Example 1.

[0030] Figure 3 X-ray diffraction spectra or X-ray photoelectron spectra of the catalysts in Example 1 and each comparative example; wherein: (a) is the X-ray diffraction spectra of Cu@NF in Comparative Example 1, CuSn / SnO2@NF in Comparative Example 2, and CuSn / Cu3P@NF in Example 1; (b) is the X-ray photoelectron spectra of Cu in CuSn / SnO2@NF in Comparative Example 2 and CuSn / Cu3P@NF in Example 1; (c) is the X-ray photoelectron spectra of Sn in CuSn / SnO2@NF in Comparative Example 2 and CuSn / Cu3P@NF in Example 1; (d) is the X-ray photoelectron spectra of P in CuSn / Cu3P@NF in Example 1.

[0031] Figure 4 The linear sweep voltammograms of CuSn / Cu3P@NF in Example 1 are shown in Figure 1 when the electrolyte contains nitrate and when it does not contain nitrate.

[0032] Figure 5 The CuSn / Cu3P@NF in Example 1 is isotopically labeled. 14 N and 15 NMR comparison images of N.

[0033] Figure 6 The Faradaic efficiency and ammonia yield of the CuSn / Cu3P@NF catalyst in Example 1, the Cu@NF in Comparative Example 1, and the CuSn / SnO2@NF in Comparative Example 2 were calculated by UV-visible spectrophotometry and nuclear magnetic resonance spectroscopy.

[0034] Figure 7 This is the removal ability diagram of the CuSn / Cu3P@NF catalyst in Example 1.

[0035] Figure 8 This is a graph showing the cycle time and number of cycles of the CuSn / Cu3P@NF catalyst in nitrate solution in Example 1. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0037] The present invention uses an electrodeposition method to deposit a copper-tin-copper-phosphorus complex on a nickel foam substrate to obtain a copper-based phosphide catalyst (CuSn / Cu3P@NF). The catalyst grows CuSn with a pine needle-like morphology in situ on the surface of a porous nanostructured nickel foam conductive substrate by regulating the electrodeposition process parameters (including electrolyte composition, deposition potential, temperature and time). / Cu3P active layer. This catalyst optimizes nitrate adsorption / activation and proton transfer kinetics through the synergistic effects of Cu, Sn, and P, significantly enhancing the selectivity and reaction rate of NO3RR. The present invention features a simple and low-cost preparation process, and the catalyst requires no precious metal components, providing a highly efficient solution for green ammonia synthesis and resource utilization of nitrate wastewater.

[0038] Example 1:

[0039] This embodiment is a method for preparing a CuSn / Cu3P@NF nanocomposite catalyst, comprising the following steps:

[0040] S1. Prepare a whole sheet of nickel foam, and cut and clean it. Specifically, first cut the whole sheet of nickel foam into 1×2cm nickel foam sheets; add acetone to immerse the nickel foam sheet, and ultrasonicate for 30 minutes (pay attention to the water temperature during ultrasonication, which should not exceed 30°C. Change the water in the ultrasonic cleaning machine every ten minutes and swap the front and back of the nickel foam to ensure uniform cleaning). After the ultrasonication is completed, wash it repeatedly with deionized water for 3-5 times; then add ethanol to immerse the nickel foam sheet, and ultrasonicate for 30 minutes (pay attention to the water temperature during ultrasonication). The water temperature should not exceed 30°C. Change the water in the ultrasonic cleaning machine every ten minutes and swap the front and back of the nickel foam to ensure uniform cleaning). After the ultrasonic cleaning is completed, rinse repeatedly with deionized water for 3-5 times. Finally, dilute 1mol / L hydrochloric acid (HCl) with a dilution ratio of 1:10, add the diluted hydrochloric acid to immerse the nickel foam, and ultrasonicate for 5 minutes (pay attention to the water temperature during the ultrasonic cleaning process, which should not exceed 30°C. Change the water in the ultrasonic cleaning machine every ten minutes and swap the front and back of the nickel foam to ensure uniform cleaning). After the ultrasonic cleaning is completed, rinse repeatedly with deionized water for 3-5 times. Store the cleaned nickel foam in deionized water and prepare for use.

[0041] S2. Prepare a deposition liquid, the deposition liquid composition is: 14.32g / L CuCl2·2H2O, 8.12g / L SnCl2·2H2O, 1.2g / L NaH2PO4, and the balance is water; the preparation process is: first weigh 1.432g of CuCl2·2H2O metal salt, add 100ml of deionized water, then weigh 0.812g of SnCl2·2H2O and 0.12g of NaH2PO4 respectively and evenly disperse them into the above solution; let the resulting 100ml mixed material stand until the metal salt is completely dissolved and there are no obvious particles or crystals, thereby obtaining the deposition liquid.

[0042] S3, electrochemical deposition: Take out 50 ml of the deposition solution prepared in step S2, and use an electrochemical workstation to deposit the ions in the deposition solution onto the nickel foam. The specific process is as follows:

[0043] The prepared nickel foam sheet was taken out and fixed on the electrode clip as the working electrode, which was then fixed in a three-electrode electrolytic cell with Ag / AgCl as the reference electrode and a graphite rod as the auxiliary electrode (counter electrode).

[0044] Connect the three electrodes to the electrochemical analyzer using Shanghai Chenhua CHI660E series; perform electrodeposition in constant current mode with a current density of 20 mA / cm 2 The deposition time was 200 seconds. After the deposition was completed, the sample was dried in a vacuum drying oven for 5 hours to obtain the CuSn / Cu3P@NF nanocomposite catalyst.

[0045] The CuSn / Cu3P@NF nanocomposite catalyst prepared in Example 1 was used to catalyze the nitrate-to-ammonia reaction: a three-electrode electrochemical system was constructed using the CuSn / Cu3P@NF nanocomposite catalyst as the working electrode, Ag / AgCl as the reference electrode, and a platinum electrode as the counter electrode. The entire electrochemical system was placed in an H-type electrolytic cell. The working electrode was first activated with a 1 mol / L KOH solution, and then an IT test was performed at room temperature using a mixed solution of KOH and KNO3 as the electrolyte. The electrolyte had a KOH concentration of 1 mol / L and a KNO3 concentration of 0.1 mol / L. The amount of ammonia generated was measured by UV-visible spectrophotometry. A comparative experiment was also conducted using a 0.1 mol / L KNO3 solution as the electrolyte.

[0046] Comparative Example 1:

[0047] First, process the nickel foam. Cut the entire sheet of nickel foam into nickel foam sheets of 1×2 cm in size. Then add acetone to immerse the nickel foam sheet and ultrasonicate for 30 minutes. After the ultrasonication is completed, rinse it repeatedly with deionized water for 3-5 times. Then add ethanol to immerse the nickel foam sheet and ultrasonicate for 30 minutes. After the ultrasonication is completed, rinse it repeatedly with deionized water for 3-5 times. Finally, dilute 1mol / L hydrochloric acid (HCl) with a dilution ratio of 1:10. Add hydrochloric acid to immerse the nickel foam sheet and ultrasonicate for 5 minutes. After the ultrasonication is completed, rinse it repeatedly with deionized water for 3-5 times. Store the cleaned nickel foam platinum sheet in deionized water and prepare for use.

[0048] Next, prepare the required electrodeposition solution by weighing 0.716g of CuCl2·2H2O metal salt and adding 50mL of deionized water. Let the resulting 50mL metal salt solution stand until the salt is completely dissolved and no particles or crystals are visible.

[0049] Finally, electrodeposition was performed. The prepared nickel foam sheet was fixed on the electrode clip as the working electrode and fixed in a three-electrode electrolytic cell. The reference electrode was Ag / AgCl and the auxiliary electrode (counter electrode) was a graphite rod. Electrodeposition was performed in constant current mode with a current density of 20 mA / cm 2 The deposition time was 200 s, and the sample obtained after drying in a forced air drying oven for 5 hours was the Cu@NF nanocatalyst.

[0050] The obtained Cu@NF nanocatalyst was subjected to an IT test at room temperature using a mixed solution of KOH and KNO3 (1 mol / L KOH, 0.1 mol / L KNO3) as the electrolyte. The test process was the same as in Example 1.

[0051] Comparative Example 2:

[0052] First, process the nickel foam. Cut the entire sheet of nickel foam into nickel foam sheets of 1×2 cm in size. Then add acetone to immerse the nickel foam sheet and ultrasonicate for 30 minutes. After the ultrasonication is completed, rinse it repeatedly with deionized water for 3-5 times. Then add ethanol to immerse the nickel foam sheet and ultrasonicate for 30 minutes. After the ultrasonication is completed, rinse it repeatedly with deionized water for 3-5 times. Finally, dilute 1mol / L hydrochloric acid (HCl) with a dilution ratio of 1:10. Add hydrochloric acid to immerse the nickel foam sheet and ultrasonicate for 5 minutes. After the ultrasonication is completed, rinse it repeatedly with deionized water for 3-5 times. Store the cleaned nickel foam platinum sheet in deionized water and prepare for use.

[0053] Next, prepare the required electrodeposition solution by weighing 0.511g of CuCl2·2H2O metal salt, adding 50ml of deionized water, and then weighing 0.677g of SnCl2·2H2O and evenly dispersing it throughout the solution. Let the resulting 50ml mixture stand until the metal salt is completely dissolved and no particles or crystals are visible.

[0054] Finally, electrodeposition was performed. The prepared nickel foam sheet was fixed on the electrode clip as the working electrode and fixed in a three-electrode electrolytic cell. The reference electrode was Ag / AgCl and the auxiliary electrode (counter electrode) was a graphite rod. Electrodeposition was performed in constant current mode with a current density of 20 mA / cm 2 The deposition time is 200 seconds, and the sample obtained after natural drying in air at room temperature is the CuSn / SnO2@NF nanocomposite catalyst (CuSn catalyst).

[0055] The obtained CuSn / SnO2@NF nanocomposite catalyst was subjected to an IT test at room temperature using a mixed solution of KOH and KNO3 (1 mol / L KOH, 0.1 mol / L KNO3) as an electrolyte. The test process was the same as in Example 1.

[0056] The results of the test analysis of the samples obtained in Example 1 and Comparative Examples 1-2 are as follows:

[0057] After scanning electron microscopy (SEM) analysis of the Cu@NF nanocatalyst prepared in Comparative Example 1, small spherical particles with complete structure can be observed. Figure 1 The CuSn / SnO2@NF nanocomposite catalyst prepared in Comparative Example 2 was subjected to scanning electron microscopy (SEM) analysis, and a broken spherical morphology was observed, as shown in FIG. Figure 1 (b) As shown in Example 1, CuSn / Cu3P@NF nanocomposite catalyst was successfully synthesized, and CuSn / Cu3P showed a pine needle-like structure, which was composed of CuSn alloy and Cu3P. Figure 2 It can be seen that compared with the CuSn / SnO2@NF nanocomposite catalyst prepared in Comparative Example 2, the catalyst originally distributed in the form of small spheres on the nickel foam in Example 1 is transformed into a pine needle-like structure due to the incorporation of phosphorus.

[0058] The X-ray diffraction (XRD) analysis of each catalyst prepared in Comparative Examples 1-2 and Example 1 is as follows: Figure 3 As shown in (a), the composition of each catalyst can be further verified. The atomic ratio of Cu to Sn in the CuSn alloy in Example 1 is 41:11 (Cu 41 Sn 11The mass ratio was obtained by inductively coupled plasma (ICP) analysis, and the molar mass was obtained by mass ratio relative to the molecular mass. By comparing the mass ratios, it was found that the molar ratio of CuSn alloy to Cu3P in the catalyst of Example 1 was approximately 1:6.667.

[0059] Figure 3 (b)-(d) show the X-ray photoelectron spectroscopy (XPS) of the catalysts in Example 1 and Comparative Example 2. Comparative results indicate that the introduction of P alters the electronic structure of Cu and Sn. This change in electronic structure optimizes the catalyst's adsorption of reactants and intermediates, potentially enhancing its catalytic activity. The catalyst's pine-needle-like structure increases the specific surface area for the reaction and increases the number of active sites.

[0060] The test results of using the catalyst samples prepared in Comparative Examples 1-2 and Example 1 to catalyze the nitrate to ammonia reaction are as follows: Figure 4-5 As shown. Figure 4 It can be seen from the linear sweep voltammetry curve that the current density of the electrolytic cell with potassium nitrate added is higher than that without potassium nitrate added, which indicates that the CuSn / Cu3P@NF nanocomposite catalyst designed in Example 1 has relatively good catalytic performance in the electrochemical catalytic test of nitrate synthesis of ammonia. In order to explore the source of nitrogen in the product NH3 of the NO3RR process and evaluate the accuracy of NH3 detection by ultraviolet spectrophotometry (UV-Vis), 1H nuclear magnetic resonance spectroscopy (1HNMR) was used for qualitative and quantitative detection and verification. The results clearly showed that the source of nitrogen in the product NH3 is indeed only from nitrate, and not from other sources, such as Figure 5 shown.

[0061] At the same time, UV-Vis and 1H NMR both proved that at room temperature, when the molar ratio of CuSn alloy to Cu3P was 1:6.667, the CuSn / Cu3P@NF nanocomposite catalyst in Example 1 showed much higher NH3 yield and Faraday efficiency than the Cu@NF in Comparative Example 1 and the CuSn / SnO2@NF in Comparative Example 2. Figure 6 As shown in Table 1. In addition, the removal test shows that the CuSn / Cu3P@NF catalyst in Example 1 can reduce the nitrogen concentration in industrial wastewater from an initial high concentration of 1200 μg·mL-1 to below the pollution limit of 11.30 μg·mL-1 in drinking water specified by the World Health Organization within 10 hours. Figure 7 Moreover, the catalyst activity in Example 1 is also very outstanding compared with similar catalysts, such as Figure 8 As shown, a certain degree of catalytic performance is retained after more than twenty cycles.

[0062] Table 1 NH3 production rate and Faradaic efficiency of catalysts in various examples and comparative examples at -0.4V (vs. RHE)

[0063] sample Ammonia yield Faraday efficiency Comparative Example 1 <![CDATA[11.38mg h -1 cm -2 ]]> 90.92％ Comparative Example 2 <![CDATA[14.77mg h -1 cm -2 ]]> 91.84％ Example 1 <![CDATA[18.02mg h -1 cm -2 ]]> 95.69％ Example 2 <![CDATA[14.87mg h -1 cm -2 ]]> 94.34％ Comparative Example 3 <![CDATA[12.1mg h -1 cm -2 ]]> 74.3％ Comparative Example 4 <![CDATA[12.9mg h -1 cm -2 ]]> 83.4％

[0064] Example 2:

[0065] This embodiment is a method for preparing a CuSn / Cu3P@NF nanocomposite catalyst. The difference from Example 1 is that when preparing the deposition liquid in step S2, the deposition liquid composition is: 13.9g / L CuCl2·2H2O, 7.78g / L SnCl2·2H2O, 1.08g / L NaH2PO4, and the balance is water; the preparation process is: first weigh 0.696g of CuCl2·2H2O metal salt, add 50ml of deionized water, then weigh 0.389g of SnCl2·2H2O and 0.054g of NaH2PO4 respectively and evenly disperse them into the above solution; let the resulting 50ml mixture stand until the metal salt is completely dissolved and there are no obvious particles or crystals, thus obtaining the deposition liquid. The remaining steps are the same as in Example 1, and the resulting CuSn / Cu3P@NF composite catalyst still has a pine needle-like morphology. The copper-tin-copper-phosphorus complex is composed of Cu 41 Sn 11 Composited with Cu3P, Cu 41 Sn 11 The molar ratio to Cu3P is 1:5.

[0066] When the obtained CuSn / Cu3P@NF nanocomposite catalyst was subjected to IT testing using a mixed solution of 1 mol / L KOH and 0.1 mol / L KNO3 as the electrolyte, the NH3 yield and Faradaic efficiency of the CuSn / Cu3P@NF composite catalyst at -0.4 V (vs. RHE) at room temperature are shown in Table 1.

[0067] Comparative Example 3:

[0068] This example describes a method for preparing a CuSn / Cu3P@NF nanocomposite catalyst. This method differs from Example 1 in that, in step S2, the deposition solution is prepared with a composition of 10.22 g / L CuCl2·2H2O, 13.52 g / L SnCl2·2H2O, 1.2 g / L NaH2PO4, and the balance water. The preparation process involves weighing 0.511 g of CuCl2·2H2O metal salt, adding 50 ml of deionized water, then weighing 0.676 g of SnCl2·2H2O and 0.06 g of NaH2PO4 and evenly dispersing them into the solution. The resulting 50 ml mixture is allowed to stand until the metal salts are completely dissolved, with no visible particles or crystals remaining. This yields the deposition solution. The remaining steps are identical to those in Example 1. The resulting CuSn / Cu3P@NF composite catalyst exhibits a pine needle-like morphology.

[0069] When the obtained CuSn / Cu3P@NF nanocomposite catalyst was subjected to IT testing using a mixed solution of 1 mol / L KOH and 0.1 mol / L KNO3 as the electrolyte, the NH3 yield and Faradaic efficiency of the CuSn / Cu3P@NF composite catalyst at -0.4 V (vs. RHE) at room temperature are shown in Table 1.

[0070] Comparative Example 4:

[0071] This example describes a method for preparing a CuSn / Cu3P@NF nanocomposite catalyst. This method differs from Example 1 in that, in step S2, the deposition solution is prepared with a composition of 16.37 g / L CuCl2·2H2O, 5.41 g / L SnCl2·2H2O, 1.2 g / L NaH2PO4, and the balance water. The preparation process involves weighing 0.818 g of CuCl2·2H2O metal salt, adding 50 ml of deionized water, then weighing 0.271 g of SnCl2·2H2O and 0.06 g of NaH2PO4 and evenly dispersing them into the solution. The resulting 50 ml mixture is allowed to stand until the metal salts are completely dissolved, with no visible particles or crystals remaining. This yields the deposition solution. The remaining steps are identical to those in Example 1. The resulting CuSn / Cu3P@NF composite catalyst exhibits a pine needle-like morphology.

[0072] When the obtained CuSn / Cu3P@NF nanocomposite catalyst was subjected to IT testing using a mixed solution of 1 mol / L KOH and 0.1 mol / L KNO3 as the electrolyte, the NH3 yield and Faradaic efficiency of the CuSn / Cu3P@NF composite catalyst at -0.4 V (vs. RHE) at room temperature are shown in Table 1.

[0073] In summary, the present invention successfully synthesized a CuSn / Cu3P@NF nanocomposite catalyst using an electrodeposition method. This method can be completed at room temperature, offering advantages such as a fast, efficient synthesis process and simple operation. Furthermore, the particle morphology of the copper-tin alloy was significantly improved, and its pine needle-like shape further facilitated catalytic activity. The synthesized CuSn / Cu3P@NF nanocomposite catalyst was applied to the electrocatalytic production of ammonia from nitrate. At room temperature, the CuSn / Cu3P@NF nanocomposite catalyst achieved an NH3 yield of 18.02 mg h at -0.4 V (vs. RHE). -1 cm -2 , with a Faradaic efficiency of 95.69%. Nickel foam is used as a substrate. On the one hand, nickel is an excellent conductive substrate for electrocatalysis; on the other hand, its excellent porous structure better meets the requirements for depositing metal nanocomposites, effectively increasing the reaction area. The addition of phosphorus changes the alloy structure, creating a pine needle-like structure that is more conducive to the catalytic reaction. These factors significantly enhance the catalyst's activity, resulting in improved cycle time and frequency of the composite catalyst, and also enhancing its removal capacity.

[0074] The above is an exemplary description of the present invention. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by other skilled in the art without expending creative labor falls within the scope of protection of the present invention.

Claims

1. A copper-based phosphide catalyst, characterized in that: The catalyst is a nano composite material obtained by taking foam nickel as a substrate and depositing a copper-tin-copper-phosphorus complex on the substrate.

2. The copper-based phosphide catalyst according to claim 1, characterized in that: The nanocomposite material is represented as CuSn / Cu3P@NF, wherein CuSn / Cu3P is a copper-tin-copper-phosphorus composite composed of a CuSn alloy and Cu3P, and NF is a foam nickel substrate; the copper-tin-copper-phosphorus composite has a pine needle-like morphology and is evenly distributed on the foam nickel substrate.

3. The copper-based phosphide catalyst according to claim 2, characterized in that: In the catalyst, the loading amount of the copper-tin-copper-phosphorus complex on the nickel foam substrate is 0.33 mg-5.28 mg / cm 2 ; The molar ratio of CuSn to Cu3P in the copper-tin-copper-phosphorus complex is 1:(4.5~7.5).

4. The method for preparing a copper-based phosphide catalyst by electrodeposition according to claim 1, wherein: The method comprises the following steps: S1. Prepare nickel foam sheets of required size and clean them; S2. Prepare a sedimentation solution, the sedimentation solution composition is: CuCl2·2H2O 13.6-14.5g / L, SnCl2·2H2O 7.60-8.25g / L, NaH2PO4 0.9-1.5g / L, and the balance is water; S3. Connecting the nickel foam sheet treated in step S1 and the deposition solution obtained in step S2 to an electrochemical workstation, and obtaining a copper-tin-copper-phosphorus complex on the surface of the nickel foam sheet by electrochemical deposition, that is, obtaining the copper-based phosphide catalyst.

5. The method for preparing a copper-based phosphide catalyst by electrodeposition according to claim 4, characterized in that: In step S1, the cleaning process is to ultrasonically clean the nickel foam sheet using acetone, ethanol and hydrochloric acid in sequence; wherein: the process of using acetone ultrasonic cleaning is: adding acetone to immerse the nickel foam sheet, ultrasonicating for 30 minutes, and repeatedly washing with deionized water 3-5 times after the ultrasonication is completed; the process of using ethanol ultrasonic cleaning is: adding ethanol to immerse the nickel foam sheet, ultrasonicating for 30 minutes, and repeatedly washing with deionized water 3-5 times after the ultrasonication is completed; the process of using hydrochloric acid ultrasonic cleaning is: diluting 1 mol / L hydrochloric acid (HCl) with a dilution ratio of 1:10; adding the diluted hydrochloric acid to immerse the nickel foam sheet, ultrasonicating for 5 minutes, and repeatedly washing with deionized water 3-5 times after the ultrasonication is completed; soaking the cleaned nickel foam sheet in deionized water for storage.

6. The method for preparing a copper-based phosphide catalyst by electrodeposition according to claim 4, wherein: In step S2, the preparation process of the deposition liquid is as follows: copper chloride dihydrate (CuCl2·2H2O) is added to water to prepare a copper chloride dihydrate solution, and then tin chloride dihydrate (SnCl2·2H2O) and sodium dihydrogen phosphate (NaH2PO4) are added in sequence according to the proportion of each solute in the deposition liquid. The resulting mixture is allowed to stand until all the solutes are dissolved (no obvious particles or crystals are left), thereby obtaining the deposition liquid.

7. The method for preparing a copper-based phosphide catalyst by electrodeposition according to claim 4, wherein: In the electrochemical deposition process of step S3, a three-electrode electrolytic cell is used, the deposition solution obtained in step S2 is used as the electrolyte, the nickel foam sheet is used as the working electrode, the graphite rod is used as the auxiliary electrode, and the Ag / AgCl electrode is used as the reference electrode for electrochemical deposition.

8. The method for preparing a copper-based phosphide catalyst by electrodeposition according to claim 4, wherein: Step S3: Electrochemical deposition adopts constant current mode with a current density of 10-40 mA / cm 2 The deposition time is 100-400 seconds. After the deposition is completed, the obtained sample is dried in a vacuum drying oven for 3-10 hours to obtain a nanocomposite material (CuSn / Cu3P@NF), which is the copper-based phosphide catalyst.

9. The use of the copper-based phosphide catalyst according to claim 1 in a nitrate reduction ammonia synthesis reaction, characterized in that: The copper-based phosphide catalyst is used in the reaction of nitrate reduction to synthesize ammonia.

10. Use of the copper-based phosphide catalyst according to claim 9 in a nitrate reduction reaction for synthesizing ammonia, characterized in that: In this application, a nitrate to be reduced is prepared into a nitrate solution, and potassium hydroxide is added to the nitrate solution to prepare an electrolyte. A three-electrode electrochemical system is constructed using the copper-based phosphide catalyst as a working electrode, Ag / AgCl as a reference electrode, and a platinum sheet electrode as a counter electrode. The entire electrochemical system is placed in an H-type electrolytic cell to synthesize ammonia through electrocatalytic nitrate reduction. In the electrolyte, the concentration of potassium hydroxide is 0.1-1 mol / / L, and the concentration of nitrate is 0.05-1.0 mol / / L.

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