Preparation method and application of P-CuCo / CF electro-catalytic material

Abstract

The invention belongs to the technical field of electro-catalytic materials, and particularly relates to a preparation method and application of a P-CuCo / CF electro-catalytic material. The preparation method comprises the following steps: firstly, carrying out electro-deposition by taking pretreated foamy copper as a conductive substrate and taking a cobalt chloride hexahydrate aqueous solution as an electrolyte, after an electroplated layer is formed on the foamy copper, washing and drying, putting the material into a hydrogen reduction furnace for reduction to obtain CuCo / CF, respectively putting NaH2PO2 and the obtained CuCo / CF into the upstream and downstream of a tubular furnace, and carrying out vacuum drying to obtain the CuCo / CF / NaH2PO2 / CuCo / CF composite material. And calcining and phosphorizing in a nitrogen atmosphere to finally obtain the P-CuCo / CF electro-catalytic material. The P-CuCo / CF electro-catalysis material obtained by the invention has relatively good catalysis efficiency in electro-catalysis nitrate reduction synthesis of ammonia, and under the voltage of-0.9 V vs.Ag / AgCl and in 0.1 M KNO3, the Faraday efficiency on ammonia reaches 97.33% through continuous electrolysis for 1 hour.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic materials, and in particular relates to a preparation method and application of a P-CuCo / CF electrocatalytic material. Background Art

[0002] In recent years, the electrochemical conversion of nitrates to ammonia has emerged as a promising "green" alternative to Haber-Bosch ammonia production. This approach offers the potential for a zero-carbon process that can be powered by sustainable energy under ambient conditions. However, nitrates, a ubiquitous pollutant in industrial and agricultural activities, can cause severe eutrophication and algal blooms in water bodies, threatening the balance of the nitrogen cycle. In this context, utilizing carbon-free electricity to convert harmful nitrates into valuable ammonia embodies the concept of sustainable development.

[0003] The electrochemical reduction of nitrate to ammonia is a complex process involving many electrochemical steps, leading to the formation of various intermediates and potential byproducts, including N2, NO, and NO. Furthermore, a major challenge facing this process is the presence of the competing hydrogen evolution reaction (HER). Considering the theoretical onset potential of the HER, hydrogen evolution becomes more favorable when the applied potential is more negative, thereby hindering the rate of ammonia production via the NO3RR. Therefore, the development and preparation of efficient catalysts are crucial to directing the reduction pathway towards the selective synthesis of ammonia. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a P-CuCo / CF electrocatalyst material with high catalytic efficiency, high selectivity and stable performance.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for preparing a P-CuCo / CF electrocatalytic material comprises the following steps:

[0007] 1) Pretreatment of copper foam: The copper foam was sequentially immersed in concentrated hydrochloric acid, ultrapure water, and ethanol for ultrasonic washing, and dried with nitrogen to obtain pure copper foam;

[0008] 2) Preparation of CuCo / CF: The copper foam obtained in step 1) is used as a conductive substrate and an aqueous solution of cobalt chloride hexahydrate is used as an electrolyte for electrodeposition. After forming an electroplated layer on the copper foam, the copper foam is washed and dried, and the dried material is then reduced in a hydrogen reduction furnace to obtain CuCo / CF;

[0009] 3) Preparation of P-CuCo / CF: NaH2PO2 was placed upstream of a tube furnace, and the CuCo / CF obtained in step 2) was placed downstream of the tube furnace. P-CuCo / CF was calcined and phosphated in a nitrogen environment, and then washed and dried overnight.

[0010] Furthermore, in the above preparation method, in step 1), the concentration of the concentrated hydrochloric acid is 6M.

[0011] Furthermore, in the above preparation method, in step 2), the concentration of the cobalt chloride hexahydrate aqueous solution is 0.1M.

[0012] Furthermore, in the above preparation method, in step 2), the electrodeposition voltage is -0.9 V vs. SCE, and the electrodeposition time is 600 s.

[0013] Furthermore, in the above preparation method, in step 2), the reduction temperature is 350° C. to 450° C., the reduction time is 2 h, and the heating rate of the hydrogen reduction furnace is 5° C. / min.

[0014] Furthermore, in the above preparation method, in step 3), the mass of the NaH2PO2 is 100 mg, 200 mg or 300 mg.

[0015] Furthermore, in the above preparation method, in step 3), the temperature of the calcination and phosphating is 250° C. to 350° C., the time is 1 hour, and the heating rate is 2° C. / min.

[0016] Furthermore, in the above preparation method, in step 3), the drying temperature is 60°C.

[0017] Application of the P-CuCo / CF electrocatalytic material prepared by any of the preparation methods described above in electrocatalytic nitrate reduction to synthesize ammonia.

[0018] Furthermore, the above application method is as follows: using an H-type electrolytic cell and a three-electrode working system, 0.5M K2SO4 is used as the electrolyte, the electrolyte is injected into the cathode chamber and the anode chamber respectively, and potassium nitrate solid particles are added to the cathode chamber; directly using the P-CuCo / CF electrocatalytic material as the working electrode, the platinum mesh as the counter electrode, and the Ag / AgCl as the reference electrode, electrocatalytic nitrate reduction to synthesize ammonia.

[0019] Furthermore, in the above application, the concentration of potassium nitrate in the electrolyte reaches 0.1M.

[0020] The P-CuCo / CF electrocatalytic material provided by the present invention exhibits high catalytic efficiency, good selectivity, and stable performance in the electrocatalytic reduction of nitrates to ammonia. At a voltage of -0.9 V vs. Ag / AgCl, the Faradaic efficiency for ammonia reached 97.33% in 0.1 M KNO₃ after one hour of continuous electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1is a scanning electron microscope image of the P-CuCo / CF electrocatalytic material.

[0022] Figure 2 is the X-ray diffraction pattern (XRD) of P-CuCo / CF electrocatalytic material.

[0023] Figure 3 This is the linear sweep voltammogram of the P-CuCo / CF electrocatalytic material for electrocatalytic nitrate reduction to ammonia.

[0024] Figure 4 This is the Faradaic efficiency diagram of the P-CuCo / CF electrocatalytic material for electrocatalytic nitrate reduction to ammonia.

[0025] Figure 5 This is a graph showing the generation rate of ammonia synthesis using the P-CuCo / CF electrocatalytic material for electrocatalytic nitrate reduction. DETAILED DESCRIPTION

[0026] In order to better understand the technical solution of the present invention, a specific embodiment is given to further illustrate it in detail, but the solution is not limited thereto.

[0027] Example 1 P-CuCo / CF electrocatalytic material

[0028] (1) The preparation method is as follows:

[0029] 1) Pretreatment of copper foam:

[0030] The foam copper (2×3cm 2 ) were sequentially immersed in 6 M HCl, ultrapure water and ethanol and ultrasonically washed for 5 min, and then dried with nitrogen to obtain pure foam copper.

[0031] 2) Preparation of CuCo / CF:

[0032] The pure copper foam obtained in step 1) was used as a conductive substrate, and a 0.1M cobalt chloride hexahydrate aqueous solution was used as an electrolyte. Electrodeposition was performed at a voltage of -0.9V vs. SCE for 600s. After a layer of electroplating layer was formed on the copper foam, the electrodeposited sample was rinsed with ultrapure water and dried with nitrogen. The dried sample was placed in a hydrogen reduction furnace and reduced at 400°C for 2h to obtain CuCo / CF.

[0033] 3) Preparation of P-CuCo / CF:

[0034] Place 200 mg of NaH2PO2 upstream of the tube furnace, and place the CuCo / CF obtained in step 2) downstream of the tube furnace. Under a nitrogen environment, calcine and phosphate at 300°C in the tube furnace for 1 h to obtain P-CuCo / CF, which is then washed with ultrapure water and ethanol, respectively, and dried in an oven at 60°C overnight.

[0035] (2) Testing

[0036] Figure 1 This is the scanning electron microscope image of the P-CuCo / CF electrocatalytic material. Figure 1 Scanning electron microscopy images at low and high magnifications show that the prepared electrocatalytic material presents a structure in which nanoparticles and nanosheets are uniformly grown on the surface of the foam copper skeleton.

[0037] Figure 2 is the X-ray diffraction pattern (XRD) of P-CuCo / CF electrocatalytic material, Figure 2 It can be seen that no crystalline phases belonging to Cu and Co oxides were observed, indicating that the metal oxides on the surface of the copper foam have been completely reduced by hydrogen. At the same time, the crystalline phases of Cu3P and CoP can be observed, indicating the successful doping of cobalt and the successful phosphating of the copper foam electrodeposition layer.

[0038] Example 2 Application of P-CuCo / CF Electrocatalytic Material in Electrocatalytic Nitrate Reduction to Ammonia

[0039] The electrochemical performance of the catalyst was tested using a CHI760 electrochemical workstation and an H-type electrolytic cell and a three-electrode working system.

[0040] The method is as follows: an H-type electrolytic cell and a three-electrode working system are used, 0.5M K2SO4 is used as the electrolyte, 15mL of the electrolyte is injected into the cathode chamber and the anode chamber respectively, and 0.152g of potassium nitrate solid particles are added to the cathode chamber to make the concentration of potassium nitrate in the electrolyte reach 0.1M; the electrochemical performance analysis is carried out directly using the P-CuCo / CF electrocatalytic material as the working electrode, the platinum mesh as the counter electrode, and the Ag / AgCl as the reference electrode. During the test, the cathode electrolyte stirring rate is 500rpm, and the linear scan speed is 0.05Vs -1 The voltage used is based on the standard hydrogen electrode.

[0041] Figure 3 This is the linear sweep voltammetric curve of the P-CuCo / CF electrocatalytic material used for electrocatalytic nitrate reduction to synthesize ammonia. Figure 3 As shown in the linear sweep voltammetry curves of the P-CuCo / CF electrocatalytic material in the electrolyte with / without KNO3, it can be found that after adding KNO3, at the same voltage, the current density of the P-CuCo / CF electrocatalytic material is larger, indicating that the P-CuCo / CF electrocatalytic material has a positive response to the reduction of nitrate.

[0042] Figure 4 This is the Faraday efficiency diagram of P-CuCo / CF electrocatalytic material for electrocatalytic nitrate reduction to ammonia. Figure 4As shown, after 1 hour of continuous electrolysis in 0.1M KNO₃, the Faradaic efficiency of P-CuCo / CF for the electroreduction of nitrate to ammonia was greater than 70% across a wide voltage window, reaching a maximum of 97.33% at -0.9V vs. Ag / AgCl. This demonstrates the high product selectivity and excellent catalytic efficiency of the P-CuCo / CF electrocatalytic material for the electroreduction of nitrate to ammonia.

[0043] Figure 5 This is the rate diagram of the electrocatalytic reduction of nitrate to ammonia by P-CuCo / CF electrocatalytic material. Figure 5 As shown in the figure, in 0.1M KNO3, after continuous electrolysis for 1 hour, the generation rate of ammonia increases with the increase of voltage, and the generation rate reaches the maximum value of 0.8765mmol h at the voltage of -1.4V vs.Ag / AgCl. -1 cm -2 .

Claims

1. A method for preparing a P-CuCo / CF electrocatalytic material, characterized in that: The steps include: 1) Pretreatment of copper foam: soak the copper foam in concentrated hydrochloric acid, ultrapure water, and ethanol in sequence for ultrasonic washing, and dry with nitrogen to obtain pure copper foam; 2) Preparation of CuCo / CF: The copper foam obtained in step 1) is used as a conductive substrate, and an aqueous solution of cobalt chloride hexahydrate is used as an electrolyte for electrodeposition, and a layer of electroplating is formed on the copper foam, and then the electroplated layer is washed and dried, and then the dried material is placed in a hydrogen reduction furnace for reduction to obtain CuCo / CF; 3) Preparation of P-CuCo / CF: NaH2PO2 was placed upstream of the tube furnace, and the CuCo / CF obtained in step 2) was placed downstream of the tube furnace. P-CuCo / CF was obtained by calcination and phosphating in a nitrogen environment, which was then washed and dried overnight.

2. The preparation method according to claim 1, characterized in that: In step 1), the concentration of concentrated hydrochloric acid is 6M.

3. The preparation method according to claim 1, characterized in that: In step 2), the concentration of the cobalt chloride hexahydrate aqueous solution is 0.1M.

4. The preparation method according to claim 1, characterized in that: In step 2), the voltage of the electrodeposition is -0.9 V vs. SCE, and the time of the electrodeposition is 600 s.

5. The preparation method according to claim 1, characterized in that: In step 2), the reduction temperature is 350° C. to 450° C., the reduction time is 2 hours, and the heating rate of the hydrogen reduction furnace is 5° C. / min.

6. The preparation method according to claim 1, characterized in that: In step 3), the mass of the NaH2PO2 is 100 mg, 200 mg or 300 mg.

7. The preparation method according to claim 1, characterized in that: In step 3), the calcination and phosphating temperature is 250°C to 350°C, the time is 1 hour, and the heating rate is 2°C / min.

8. The preparation method according to claim 1, characterized in that: In step 3), the drying temperature is 60°C.

9. Use of the P-CuCo / CF electrocatalytic material prepared by the preparation method according to any one of claims 1 to 8 in electrocatalytic nitrate reduction to synthesize ammonia.

10. The use according to claim 9, characterized in that: The method is as follows: an H-type electrolytic cell and a three-electrode working system are used, 0.5M K2SO4 is used as the electrolyte, the electrolyte is injected into the cathode chamber and the anode chamber respectively, and potassium nitrate solid particles are added into the cathode chamber; P-CuCo / CF electrocatalytic material is directly used as the working electrode, platinum mesh is used as the counter electrode, and Ag / AgCl is used as the reference electrode to electrocatalyze nitrate reduction to synthesize ammonia.

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