A copper-phosphorus / cobalt foam composite catalyst, its preparation method and application
By preparing copper-phosphorus/foam cobalt composite catalysts, the problem of insufficient catalyst activity and stability in the prior art is solved, and an efficient and low-cost electrochemical ammonia synthesis process is achieved, which is suitable for large-scale production.
Patent Information
- Application Number
- CN202510364473.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2025-06-27
- Estimated Expiration
- 2045-03-26
AI Technical Summary
In the electrochemical synthesis of ammonia, the activity and stability of the catalyst are insufficient, resulting in low ammonia yield, high cost of precious metal catalysts and scarce resources, which limits large-scale applications.
A catalyst with excellent electrochemical activity and stability was prepared by pretreatment of cobalt foam, alkali treatment, copper plating electrodeposition and phosphating annealing treatment.
It significantly improves the ammonia production efficiency of nitrate reduction synthesis, reduces the reaction dynamic potential energy, and has good stability and low cost, which is suitable for large-scale production.
Smart Images
Figure CN119877023B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalysts, and particularly relates to a copper-phosphorus / cobalt foam composite catalyst, a preparation method thereof, and an application thereof. Background Art
[0002] With the global energy structure transforming towards clean and low-carbon, green ammonia synthesis technology, as an important chemical production process, has received extensive attention. Ammonia is not only a key raw material for fertilizer production but also regarded as a potential clean energy carrier. The traditional Haber-Bosch method is currently the main method for industrial ammonia synthesis, but it relies on fossil fuels as the hydrogen source, has harsh reaction conditions (high temperature and high pressure), and is accompanied by a large amount of carbon dioxide emissions, which is not conducive to sustainable development. Therefore, the development of green and low-carbon ammonia synthesis technology has become a current research hotspot.
[0003] Electrochemical ammonia synthesis is a highly potential green ammonia production route, which uses electrochemical reactions to convert nitrogen or nitrate into ammonia. When using nitrogen as the nitrogen source, due to its poor solubility in water, strong N≡N bond energy that is difficult to activate, and the limitation of the competing hydrogen evolution reaction, the ammonia production rate is extremely low (about 0.1 - 100 μg h -1 mg cat -1 ), so this technology still cannot be used for large-scale ammonia production. When using nitrate as the nitrogen source, it can not only realize the resource utilization of nitrate in wastewater but also reduce the dependence on fossil fuels and lower carbon emissions. However, the core challenge of the nitrate reduction electrochemical reaction lies in the development of efficient and stable catalysts.
[0004] Currently, noble metal catalysts such as platinum, palladium, ruthenium, etc. have high catalytic activity, but their high cost and scarce resources limit their large-scale application. In addition, for the single-crystal plane copper metal simple substance with relatively excellent performance, the strong adsorption of the intermediate nitrogen-containing substances will lead to stability problems and is prone to rapid deactivation during the reduction process. Moreover, at low overpotentials, the weak adsorption of hydrogen radicals on Cu will limit the hydrogenation rate, and at high overpotentials, the hydrogen evolution reaction will dominate, resulting in insufficient conversion of ammonia products.
[0005] Cobalt-based materials are considered as potential non-noble metal catalyst candidate materials due to their rich natural resources, low cost, and good performance. However, the activity and selectivity of pure cobalt materials in the nitrate reduction ammonia synthesis reaction are insufficient and difficult to meet the actual application requirements. Summary of the Invention
[0006] In view of the above problems, the present invention aims to provide a copper-phosphorus / cobalt foam composite catalyst, a preparation method thereof, and an application thereof.
[0007] The technical solution of the present invention is as follows:
[0008] On the one hand, a preparation method of a copper-phosphorus / cobalt foam composite catalyst is provided, including the following steps:
[0009] S1: Obtain cobalt foam and perform pretreatment on the cobalt foam;
[0010] S2: Perform alkali treatment on the pretreated cobalt foam to obtain a cobalt oxyhydroxide precursor with a double-layer hydroxide structure;
[0011] S3: Prepare a copper plating electrolyte and place the cobalt oxyhydroxide precursor in the copper plating electrolyte for electrodeposition to obtain a copper / cobalt foam precursor;
[0012] S4: Perform phosphating annealing treatment on the copper / cobalt foam precursor to obtain the copper-phosphorus / cobalt foam composite catalyst.
[0013] Preferably, in step S1, the pretreatment includes sequentially performing ultrasonic cleaning treatment with hydrochloric acid solution, absolute ethanol, and deionized water.
[0014] Preferably, in step S2, when performing alkali treatment, place the pretreated cobalt foam in a sodium hydroxide solution and keep it warm at 75 - 85 °C for 12 - 14 h.
[0015] Preferably, the concentration of the sodium hydroxide solution is 1 - 4 mol / L.
[0016] Preferably, in step S3, the electrolyte of the copper plating electrolyte is any one or more of copper chloride, copper sulfate, and copper nitrate.
[0017] Preferably, the concentration of the copper plating electrolyte is 1 - 4 mol / L.
[0018] Preferably, in step S3, when performing electrodeposition, electrodeposit at a constant voltage of -2 to -2.5 V vs. RHE for 100 - 600 s.
[0019] Preferably, in step S4, the phosphating annealing treatment of the copper / cobalt foam precursor specifically includes the following sub-steps: Place the copper / cobalt foam precursor and sodium hypophosphite powder in a tubular furnace, heat it to 400 °C at a rate of 1 - 3 °C / min in an argon atmosphere, and keep it warm for 20 - 30 min.
[0020] On the other hand, a copper-phosphorus / cobalt foam composite catalyst prepared by using the preparation method of the copper-phosphorus / cobalt foam composite catalyst described in any one of the above and its application in the reduction of nitrate to synthesize ammonia are also provided.
[0021] The beneficial effects of the present invention are:
[0022] The preparation method of the present invention is simple and low-cost. The prepared copper-phosphorus / cobalt foam composite catalyst has excellent electrochemical activity and stability, can be applied to the electrocatalytic nitrate reduction reaction for ammonia synthesis, reduce the reaction kinetic potential energy of nitrate reduction to ammonia, and significantly improve the ammonia synthesis efficiency. Description of the Drawings
[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0024] Figure 1 It is a schematic flow chart of the preparation method of the copper-phosphorus / cobalt foam composite catalyst of the present invention;
[0025] Figure 2 It is the surface SEM image of the copper-phosphorus / cobalt foam composite catalyst in Example 1;
[0026] Figure 3 It is the TEM image of the copper-phosphorus / cobalt foam composite catalyst in Example 1;
[0027] Figure 4 It is the XRD images of the copper-phosphorus / cobalt foam composite catalyst before and after the electrochemical ammonia synthesis reaction in Example 1;
[0028] Figure 5 It is the ammonia production activity and Faraday efficiency diagram of the copper-phosphorus / cobalt foam composite catalyst in Example 1;
[0029] Figure 6 It is the long-term electrolysis stability test of the copper-phosphorus / cobalt foam composite catalyst in Example 1 at -0.3 V vs. RHE;
[0030] Figure 7 It is the change of the product content of the copper-phosphorus / cobalt foam composite catalyst with time during the nitrate reduction process in Example 1;
[0031] Figure 8 It is the cyclicity test of the copper-phosphorus / cobalt foam composite catalyst in Example 1 at -0.3 V vs. RHE. Detailed Embodiments
[0032] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, without conflict, the embodiments in the present application and the technical features in the embodiments may be combined with each other. It should be pointed out that, unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs. The terms "including" or "comprising" and the like used in the disclosure of the present invention mean that the elements or objects appearing before the term cover the elements or objects listed after the term and their equivalents, without excluding other elements or objects.
[0033] On the one hand, as Figure 1 shown, the present invention provides a method for preparing a copper-phosphorus / cobalt foam composite catalyst, comprising the following steps:
[0034] S1: Obtain cobalt foam and perform pretreatment on the cobalt foam.
[0035] In a specific embodiment, the pretreatment includes sequentially performing ultrasonic cleaning treatment with hydrochloric acid solution, absolute ethanol, and deionized water. Optionally, the concentration of the hydrochloric acid solution is 0.5 - 1 mol / L, and the time for ultrasonic cleaning treatment is 15 - 20 min.
[0036] It should be noted that the purpose of the pretreatment is to remove impurities such as oxides and organic substances on the surface of the cobalt foam. In addition to the preferred pretreatment method in the above embodiment, other pretreatment methods in the prior art that can achieve this purpose can also be applied to the present invention.
[0037] S2: Perform alkali treatment on the pretreated cobalt foam to obtain a cobalt oxyhydroxide precursor with a double-layer hydroxide structure.
[0038] In a specific embodiment, when performing the alkali treatment, place the pretreated cobalt foam in a sodium hydroxide solution and keep it warm at 75 - 85 °C for 12 - 14 h. Optionally, the concentration of the sodium hydroxide solution is 1 - 4 mol / L.
[0039] It should be noted that the purpose of the alkali treatment is to hydroxylate the cobalt foam to form a cobalt oxyhydroxide precursor with a double-layer hydroxide structure. In addition to the alkali treatment method in the above embodiment, alkali treatment methods formed by changing the type of alkali (such as potassium hydroxide, etc.), the concentration of the alkali, the temperature and time of the alkali treatment, as long as they can achieve this purpose, the corresponding alkali treatment methods can also be applied to the present invention.
[0040] S3: Prepare a copper plating electrolyte and place the cobalt oxyhydroxide precursor in the copper plating electrolyte for electrodeposition to obtain a copper / cobalt foam precursor.
[0041] In a specific embodiment, the electrolyte of the copper plating electrolyte is any one or more of copper chloride, copper sulfate, and copper nitrate. Optionally, the concentration of the copper plating electrolyte is 1 to 4 mol / L.
[0042] In a specific embodiment, during electro-deposition, electro-deposition is carried out at a constant voltage of -2 to -2.5 V vs. RHE for 100 to 600 s.
[0043] It should be noted that electro-deposition copper plating is a prior art. The copper plating electrolyte and electro-deposition parameters in the above embodiments are only the preferred embodiments of the present invention, and other copper plating electrolytes and electro-deposition parameters that can also achieve electro-deposition copper plating are also applicable to the present invention.
[0044] S4: Perform phosphating annealing treatment on the copper / cobalt foam precursor to obtain the copper-phosphorus / cobalt foam composite catalyst.
[0045] In a specific embodiment, the phosphating annealing treatment of the copper / cobalt foam precursor specifically includes the following sub-steps: Place the copper / cobalt foam precursor and sodium hypophosphite powder in a tubular furnace, and heat it to 400 °C at a rate of 1 to 3 °C / min in an argon atmosphere, and keep it warm for 20 to 30 min.
[0046] It should be noted that phosphating annealing treatment is a prior art. The phosphating annealing parameters in the above embodiments are only the preferred embodiment parameters of the present invention, and other parameters that can also achieve phosphating annealing treatment are also applicable to the present invention.
[0047] In the present invention, the preparation method of the copper-phosphorus / cobalt foam composite catalyst uses cobalt foam as the substrate, and then a coating layer composed of phosphorus nanoparticles and copper nanoparticles is covered on the cobalt foam substrate, so that the macroporous framework structure of the cobalt foam substrate is retained. The phosphorus nanoparticles and the copper nanoparticles are evenly distributed on the surface of the cobalt foam substrate, showing a sheet structure of nanoparticle accumulation.
[0048] On the other hand, the present invention also provides a copper-phosphorus / cobalt foam composite catalyst prepared by using the preparation method of the copper-phosphorus / cobalt foam composite catalyst described in any one of the above, and its application in the reduction of nitrate to synthesize ammonia.
[0049] In a specific embodiment, when using the copper-phosphorus / cobalt foam composite catalyst of the present invention for nitrate reduction to synthesize ammonia, the copper-phosphorus / cobalt foam composite catalyst is used as the cathode electrode, and a nitrate solution is used as the electrolyte, and nitrate is electrocatalytically reduced to ammonia in a three-electrode electrochemical system.
[0050] Optionally, the nitrate solution is any one or more of sodium nitrate solution, potassium nitrate solution, sodium nitrite solution, and potassium nitrite solution. The concentration of the nitrate solution is 0.1 - 2 mol / L. The solvent of the nitrate solution is sodium hydroxide solution or potassium hydroxide solution, so that the pH of the nitrate solution is 13 - 14, and the voltage in the process of electrocatalytic reduction of nitrate is 0 - -0.3 V relative to the hydrogen standard electrode potential. In this embodiment, by using an alkaline nitrate solution, the conductivity of the solution can be increased and the rate of the electrolysis reaction can be accelerated.
[0051] It should be noted that the electrocatalytic synthesis of ammonia using a catalyst is a prior art. The electrochemically synthesized ammonia parameters in the above embodiments are only the preferred embodiment parameters of the present invention. Other methods of electrocatalytic synthesis of ammonia with changed parameters are also applicable to the present invention.
[0052] Example 1
[0053] A copper - phosphorus / cobalt foam composite catalyst is prepared by the following steps:
[0054] (1) Obtain cobalt foam (with dimensions of 2.0 cm × 2.0 cm × 0.2 cm), and perform pretreatment on the cobalt foam. Specifically: ultrasonically clean in a dilute hydrochloric acid solution (with a concentration of 1 mol / L) and ethanol for 15 min in sequence to remove surface oil stains and oxides, and then ultrasonically clean with deionized water for 15 min, rinse and dry, and set aside for later use;
[0055] (2) Place the pretreated cobalt foam in 70 mL of sodium hydroxide solution (with a concentration of 4 mol / L), and keep it warm in an oil bath at 80 °C for 12 h. After the heat preservation ends, cool, wash, and dry to obtain a cobalt oxyhydroxide precursor with a double - layer hydroxide structure;
[0056] (3) Prepare a copper - plating electrolyte (a copper chloride solution with a concentration of 4 mol / L) as the electrodeposition solution. Use the cobalt oxyhydroxide precursor as the working electrode and a platinum sheet as the counter electrode. Using an electrochemical workstation, perform electrodeposition at a constant voltage of -2.0107 V vs. RHE for 300 s to obtain a copper / cobalt foam precursor;
[0057] (4) Place the copper / cobalt foam precursor in a tubular furnace, and place 0.5 g and 0.1 g of sodium hypophosphite powder at the upstream and downstream respectively. Heat it to 400 °C at a rate of 2 °C / min in an argon atmosphere, and keep it warm for 30 min to obtain the copper - phosphorus / cobalt foam composite catalyst.
[0058] Example 2
[0059] Different from Example 1, in this embodiment, the electrodeposition times in step (3) are 100 s, 200 s, 400 s, 500 s, and 600 s respectively.
[0060] Example 3
[0061] Different from Example 1, the phosphating annealing treatment times in step (4) of this example are 1 h, 1.5 h, and 2 h respectively.
[0062] Comparative Example 1
[0063] Different from Example 1, this comparative example does not include steps (2) to (4), that is, the pretreated cobalt foam is used as a pure cobalt catalyst.
[0064] Comparative Example 2
[0065] Different from Example 1, this comparative example does not include step (3), that is, directly performing phosphating annealing treatment on the cobalt oxyhydroxide precursor to obtain a phosphorus / cobalt foam catalyst.
[0066] Comparative Example 3
[0067] Different from Example 1, this comparative example does not include step (4), that is, not performing phosphating annealing treatment to obtain a copper / cobalt foam catalyst.
[0068] Comparative Example 4
[0069] Different from Example 1, the substrate in step (1) of this comparative example is copper foam, and a cobalt plating electrolyte (cobalt chloride solution with a concentration of 4 mol / L) is prepared in step (3) for electrodeposition cobalt plating to obtain a cobalt-phosphorus / copper foam catalyst.
[0070] Comparative Example 5
[0071] Different from Example 1, this comparative example does not include step (2), that is, not performing alkali treatment to obtain an un-alkali-treated copper-phosphorus / cobalt foam catalyst.
[0072] Test Example
[0073] The morphologies of the catalysts of each example and each comparative example were observed by using a Geminisem 300 scanning electron microscope (SEM, Zeiss, Germany) and a transmission electron microscope. Among them, the surface SEM image of the copper-phosphorus / cobalt foam composite catalyst of Example 1 is as Figure 2 shown, and the TEM image of the copper-phosphorus / cobalt foam composite catalyst of Example 1 is as Figure 3 shown. From Figure 2 and Figure 3 it can be seen that the surface of the copper-phosphorus / cobalt foam composite catalyst of the present invention presents an irregularly stacked matrix morphology and has polycrystalline properties, which is because the copper-phosphorus / cobalt foam composite catalyst of the present invention is composed of many copper nanoparticles and phosphorus nanoparticles with different orientations.
[0074] The structures of the catalysts of each example and each comparative example were observed using an X-ray diffractometer. The XRD pattern of the copper-phosphorus / cobalt foam composite catalyst of Example 1 is as follows Figure 4 shown, where (a) is the XRD pattern of the copper-phosphorus / cobalt foam composite catalyst of the present invention before the electrochemical synthesis of ammonia, and (b) is the XRD pattern of the copper-phosphorus / cobalt foam composite catalyst of the present invention after 200 h of the electrochemical synthesis of ammonia. It can be seen from Figure 4 that the position of the main peak did not shift and the types of peaks did not significantly decrease before and after the reaction. This indicates that the structure of the copper-phosphorus / cobalt foam composite catalyst of the present invention did not collapse after continuous reaction, demonstrating that the copper-phosphorus / cobalt foam composite catalyst of the present invention has good material structure stability. Combining with the SEM and TEM images, it shows that the irregular packing matrix can improve the stability of the catalyst material.
[0075] The catalysts of each example and each comparative example were used for the synthesis of ammonia by nitrate reduction. Electrochemical measurements were carried out on a three-electrode electrochemical workstation (CHI760E) in an electrolyte of 1 mol / L KOH + 0.1 mol / L KNO3 at a voltage of -0.3 V vs. RHE. The Faraday efficiency and ammonia production rate were analyzed, and nitrate reduction with long time and multiple cycles was carried out at a potential of -0.3 V vs. RHE to verify the stability of the copper-phosphorus / cobalt foam composite catalyst. The copper-phosphorus / cobalt foam composite catalyst, platinum sheet, and Hg / HgO of the present invention were used as the working electrode, counter electrode, and reference electrode, respectively. Linear sweep voltammetry (LSV) tests were carried out at a scan rate of 10 mV s -1 . The method for testing ammonia production was as follows: the reaction solution after 30 min of constant potential nitrate reduction at different potentials was taken, diluted by an appropriate multiple, and the absorbance was measured using the salicylic acid colorimetric method. The ammonia production rate was calculated according to the fitting formula of the standard curve, and the Faraday efficiency was calculated according to the formula FE = (moles of product × molar mass of product) / (quantity of input charge × electronic charge). Some test results are shown in Table 1 and Figures 5 - 8 shown.
[0076] Table 1 Performance test results of each example and each comparative example
[0077]
[0078] It can be seen from Figure 5 that for the copper-phosphorus / cobalt foam composite catalyst prepared in Example 1, from 0 V to -0.4 V vs. RHE, the Faraday efficiency ranges from 60% to about 80%, showing a trend of first increasing and then decreasing, and reaching the highest value of 80.2% at -0.3 V vs. RHE. The ammonia production rate shows a trend of gradually increasing and tending to be stable.
[0079] From Figure 6 It can be seen the production of ammonium and nitrite ions and the consumption of nitrate ions by the copper-phosphorus / cobalt foam composite catalyst prepared in Example 1 at -0.3 V vs. RHE. Specifically, as time prolongs, the content of NO3 - -N increases gradually from 0.0135 min -1 to 0.0398 min -1 , which is due to the enhanced electron availability or the atomic hydrogen radicals being at a more negative potential. As the potential continues to rise, the nitrate removal rate tends to stabilize, indicating that the increase in the removal rate may not be able to offset the decrease in energy utilization efficiency caused by the high voltage, and the excess hydrogen tends to recombine into hydrogen. In addition, the generation of hydrogen bubbles will hinder the reaction active sites and the adsorption of nitrate and other intermediates. The copper-phosphorus / cobalt foam composite catalyst described in the present invention can have high catalytic activity at a low overpotential.
[0080] From Figure 7 It can be seen that during the long-term electrolysis process of the copper-phosphorus / cobalt foam composite catalyst prepared in Example 1 in a strong alkaline solution, there is no sharp change in the current density, indicating that the copper-phosphorus / cobalt foam composite catalyst described in the present invention has good stability.
[0081] From Figure 8 It can be seen that during 22 cycles of nitrate reduction by the copper-phosphorus / cobalt foam composite catalyst prepared in Example 1 at -0.3 V vs. RHE potential, neither the ammonia production rate of electrocatalytic nitrate reduction to ammonia nor the Faraday efficiency during the entire cycle process shows a significant change, indicating that the copper-phosphorus / cobalt foam composite catalyst described in the present invention has good stability.
[0082] As can be seen from Table 1, neither the pure cobalt catalyst (Comparative Example 1) nor the phosphorus / cobalt foam catalyst without electrodeposited copper (Comparative Example 2) can reach the ammonia production rate and Faraday efficiency achievable by the present invention. Although the copper / cobalt foam catalyst without phosphating treatment (Comparative Example 3) can reach a Faraday efficiency of about 71%, its stability is poor. For the cobalt-phosphorus / cobalt foam catalyst (Comparative Example 4) obtained by using copper foam as the substrate, then plating cobalt on it and performing phosphating annealing treatment, and the copper-phosphorus / cobalt foam catalyst without alkali treatment (Comparative Example 5) obtained without alkali treatment, their ammonia production efficiencies cannot reach the ammonia production efficiency achievable by the present invention, and their Faraday efficiencies also cannot reach the Faraday efficiency achievable by the present invention, and particle aggregation will occur during the stability test.
[0083] In summary, the present invention can prepare a copper-phosphorus / cobalt foam catalyst with good catalytic activity, high stability and no aggregation. Compared with the prior art, the present invention has made significant progress.
[0084] As described above, these are only representative embodiments of the present invention and do not impose any formal restrictions on the present invention. Any person skilled in the relevant art can, without departing from the scope of the technical solution of the present invention, make some modifications or decorations to the above-disclosed technical content to obtain equivalent embodiments of the present invention. However, any simple modifications, equivalent changes, and decorations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.
Claims
1. A method for preparing a copper-phosphorus / foamed cobalt composite catalyst, characterized in that: The following steps are involved: S1: obtaining foamed cobalt and pretreating the foamed cobalt; S2: treating the pretreated cobalt foam with alkali to obtain a cobalt oxyhydroxide precursor having a double-layer hydroxyl structure; S3: preparing a copper plating electrolyte, and placing the cobalt oxyhydroxide precursor in the copper plating electrolyte for electrodeposition to obtain a copper / foam cobalt precursor; during the electrodeposition, the electrodeposition is performed at a constant voltage of -2 to -2.5 V vs. RHE for 100 to 600 s; S4: performing phosphating annealing treatment on the copper / foam cobalt precursor to obtain the copper-phosphorus / foam cobalt composite catalyst; The phosphating annealing treatment of the copper / cobalt foam precursor specifically includes the following sub-steps: placing the copper / cobalt foam precursor and sodium hypophosphite powder in a tube furnace, heating to 400° C. at 1-3° C. / min in an argon atmosphere, and keeping the temperature for 20-30 min; The copper-phosphorus / foam cobalt composite catalyst uses foam cobalt as a substrate, which is covered with a coating layer consisting of phosphorus nanoparticles and copper nanoparticles. The phosphorus nanoparticles and the copper nanoparticles are evenly distributed on the surface of the foam cobalt substrate to present a sheet structure of nanoparticle stacking. The surface of the copper-phosphorus / foam cobalt composite catalyst presents an irregular stacking matrix morphology.
2. The method for preparing the copper-phosphorus / foamed cobalt composite catalyst according to claim 1, characterized in that: In step S1, the pretreatment includes ultrasonic cleaning using hydrochloric acid solution, anhydrous ethanol and deionized water in sequence.
3. The method for preparing the copper-phosphorus / foamed cobalt composite catalyst according to claim 1, characterized in that: In step S2, when the alkali treatment is performed, the pretreated foamed cobalt is placed in a sodium hydroxide solution and kept warm at 75-85° C. for 12-14 hours.
4. The method for preparing the copper-phosphorus / foamed cobalt composite catalyst according to claim 3, characterized in that: The concentration of the sodium hydroxide solution is 1-4 mol / L.
5. The method for preparing the copper-phosphorus / foamed cobalt composite catalyst according to claim 1, characterized in that: In step S3, the electrolyte of the copper plating electrolyte is any one or more of copper chloride, copper sulfate, and copper nitrate.
6. The method for preparing the copper-phosphorus / foamed cobalt composite catalyst according to claim 5, characterized in that: The concentration of the copper plating electrolyte is 1-4 mol / L.
7. A copper-phosphorus / foam cobalt composite catalyst, characterized in that: The catalyst is prepared by the method for preparing the copper-phosphorus / foamed cobalt composite catalyst described in any one of claims 1 to 6.
8. Use of the copper-phosphorus / foamed cobalt composite catalyst as claimed in claim 7 in the synthesis of ammonia by nitrate reduction.