Nickel-based composite electrocatalyst, preparation method thereof and application of nickel-based composite electrocatalyst in electrocatalytic reaction

Abstract

The invention provides a nickel-based composite electrocatalyst, a preparation method thereof and application of the nickel-based composite electrocatalyst in electrocatalytic reaction, and relates to the technical field of electrocatalysts. The preparation method provided by the invention comprises the following steps: stirring and dissolving metal nitrate and a phosphorus source to prepare a mixed solution; immersing a carbon base material in the mixed solution for solvothermal reaction, and then separating to obtain a composite intermediate; and carrying out electrodeposition on the composite intermediate in an electrolyte solution by adopting cyclic voltammetry to obtain the nickel-based composite electrocatalyst. The preparation method is simple, complex equipment is not needed, the cost is low, the adjustable and controllable electrocatalyst with excellent performance is prepared, the catalytic activity and catalytic stability in the electrocatalytic process are improved, and the application of biomass electrocatalytic conversion can be effectively promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalysts, and in particular to a nickel-based composite electrocatalyst and a preparation method thereof and application thereof in electrocatalytic reactions. Background Art

[0002] The technology of preparing high-value-added chemicals with biomass derivatives to replace related petrochemical conversion technologies has become one of the key technologies in the emerging field of biomanufacturing. Combining this technology with the use of green electricity converted from solar energy and wind energy, that is, using electricity to drive biomass conversion, has greater economic and social value such as "carbon sink" conservation and green environmental protection, and has attracted much attention.

[0003] Similar to other electrochemical conversion application systems, the application of biomass conversion driven by electricity is seriously hindered by the difficulty in balancing the cost and efficiency of the electrocatalytic system: precious metal catalysts have good performance but are expensive and difficult to control side reactions, making them difficult to use; non-precious metal catalysts have poor performance and poor stability and are difficult to meet application standards. Therefore, the development of cheap, durable, and efficient biomass conversion electrocatalysts and processes is the core and forward-looking demand for promoting the application of biomass electrocatalytic conversion. Summary of the invention

[0004] The purpose of the present invention is to provide a nickel-based composite electrocatalyst, a preparation method thereof and an application in an electrocatalytic reaction. By adopting a solvent thermal growth method, a phosphate additive layer can be covered on the surface of a carbon substrate, and then nickel-based nanoparticles are grown on the phosphate additive layer by an electrochemical growth method, thereby effectively improving the bonding tightness between the phosphate additive layer and the nickel-based nanoparticles, while improving the catalytic activity and catalytic stability in the electrocatalytic process. The preparation method is simple and does not require the use of complex equipment, and can effectively promote the application of biomass electrocatalytic conversion.

[0005] In a first aspect, the present invention provides a method for preparing a nickel-based composite electrocatalyst, comprising: stirring and dissolving a metal nitrate and a phosphorus source to obtain a mixed solution; immersing a carbon substrate in the mixed solution for a solvothermal reaction and then separating a composite intermediate; and electrodepositing the composite intermediate in an electrolyte solution using cyclic voltammetry to obtain a nickel-based composite electrocatalyst; wherein nickel acetate, sodium hypophosphite, ammonium chloride, and sodium chloride are dissolved in the electrolyte solution.

[0006] Optionally, the metal nitrate includes one of rare earth nitrate, lithium nitrate and strontium nitrate.

[0007] Optionally, the phosphorus source includes one of sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, and phytic acid.

[0008] Optionally, the carbon substrate includes one of carbon paper and carbon cloth.

[0009] Optionally, the molar ratio of the metal nitrate to the phosphorus source in the mixed solution is (0.2-0.5):1.

[0010] Optionally, the solvent in the mixed solution includes a mixture of methanol and water, and the volume fraction of the methanol in the mixed solution is less than or equal to 5%.

[0011] Optionally, the carbon substrate is immersed in the mixed solution, and the composite intermediate is separated after reacting at 150° C.-180° C. for 8 h-24 h.

[0012] Optionally, a complex intermediate is prepared by performing a solvothermal reaction, separating, washing, and drying.

[0013] Optionally, the molar ratio of the nickel acetate, the sodium hypophosphite, ammonium chloride and sodium chloride in the electrolyte solution is 1:(5-15):(5-15):(5-15).

[0014] Optionally, when the electrodeposition is performed by cyclic voltammetry, the electrodeposition is cycled 5 to 20 times at a voltage range of 0.1 V to 0.3 V and a scan rate of 2 mV / s to 10 mV / s.

[0015] Optionally, washing is performed after electrodeposition, and the nickel-based composite electrocatalyst is prepared after drying at 60° C.-80° C.

[0016] In a second aspect, the present invention also provides a nickel-based composite electrocatalyst prepared by any of the above optional preparation methods, comprising a carbon matrix and a phosphate additive layer grown on the surface of the carbon matrix, and nickel-based nanoparticles are grown on the surface of the phosphate additive layer.

[0017] In a third aspect, the present invention also provides an application of a nickel-based composite electrocatalyst prepared by any of the above optional preparation methods in an electrocatalytic reaction.

[0018] Optionally, the application includes electrocatalytic oxidation of furan aldehyde biomass to furan carboxylic acid compounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A flow chart of a method for preparing a nickel-based composite electrocatalyst provided by the present invention;

[0020] Figure 2 This is a scanning electron microscope image of the carbon cloth, the composite intermediate and the nickel-based composite electrocatalyst in Example 1 of the present invention;

[0021] Figure 3 This is a high-magnification transmission electron microscopy image of the nickel-based composite electrocatalyst prepared in Example 1 of the present invention;

[0022] Figure 4This is a performance diagram of the stability test of the nickel-based composite electrocatalyst prepared in Example 1 of the present invention after 10 consecutive cycles of electrolysis. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with general skills in the field to which the present invention belongs.

[0024] See also Figure 1 The present invention provides a method for preparing a nickel-based composite electrocatalyst, comprising:

[0025] S1, stirring and dissolving a metal nitrate and a phosphorus source to prepare a mixed solution;

[0026] S2, immersing the carbon substrate in the mixed solution for solvothermal reaction and then separating the composite intermediate;

[0027] S3. Electrodepositing the composite intermediate in an electrolyte solution by cyclic voltammetry to obtain a nickel-based composite electrocatalyst.

[0028] In fact, the metal nitrate used in step S1 includes one of rare earth nitrate, lithium nitrate, and strontium nitrate, and the phosphorus source used includes one of sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, and phytic acid. Specifically, the phosphate formed by the metal element in the metal nitrate is insoluble in water, so it can be generated on the surface of the carbon cloth during the solvent thermal reaction.

[0029] In some embodiments, after the mixed solution is prepared in step S1, the molar ratio of the metal nitrate to the phosphorus source in the mixed solution is (0.2-0.5): 1. In addition, the solvent in the mixed solution includes a mixture of methanol and water, and the volume fraction of methanol in the mixed solution is less than or equal to 5%.

[0030] In some embodiments, when performing step S2, the carbon substrate is immersed in the mixed solution, reacted at 150° C.-180° C. for 8 h-24 h, and then separated to obtain a composite intermediate. In addition, after the solvent thermal reaction, the composite intermediate is separated, washed, and then dried. In addition, the carbon substrate used includes one of carbon paper and carbon cloth, and both carbon paper and carbon cloth can be commercially available products.

[0031] In some embodiments, nickel acetate, sodium hypophosphite, ammonium chloride, and sodium chloride are dissolved in the electrolyte solution used in step S3, and the molar ratio of nickel acetate, sodium hypophosphite, ammonium chloride, and sodium chloride is 1: (5-15): (5-15): (5-15). Specifically, when performing step S3 by cyclic voltammetry for electrodeposition, the voltage range is 0.1V-0.3V and the scan rate is 2mV / s-10mV / s. Cycle 5-20 times. In addition, washing is performed after electrodeposition, and the nickel-based composite electrocatalyst is obtained after drying at 60°C-80°C.

[0032] The present invention also provides a nickel-based composite electrocatalyst prepared by the preparation method in any of the above embodiments, comprising a carbon matrix and a phosphate additive layer grown on the surface of the carbon matrix, and nickel-based nanoparticles are grown on the surface of the phosphate additive layer.

[0033] The present invention also provides an application of a nickel-based composite electrocatalyst prepared by the preparation method in any of the above embodiments in an electrocatalytic reaction, specifically, the application includes electrocatalytic oxidation of furan aldehyde biomass to furan carboxylic acid compounds.

[0034] In fact, when the furan aldehyde biomass is electrocatalytically oxidized to furan carboxylic acid compounds, the reaction includes: adding a nickel-based composite electrocatalyst to an electrolyte solution containing furan aldehyde biomass and potassium hydroxide, in a three-electrode chemical system, using the nickel-based composite electrocatalyst as a working electrode, the Hg / HgO electrode as a reference electrode, and the platinum sheet as a counter electrode, and performing an electrocatalytic conversion reaction in the range of 1.2V-1.6V using a constant potential scan, the reaction time is 0.5h-3.0h, and the reaction temperature is room temperature 25°C. Specifically, the amount of the nickel-based composite electrocatalyst is related to the size of the electrode, and the concentration of the furan aldehyde biomass substrate is 0.02mol / L-0.2mol / L, and the concentration of potassium hydroxide is 0.2mol / L-1.0mol / L.

[0035] Example 1

[0036] This embodiment 1 provides a method for preparing a nickel-based composite electrocatalyst, comprising the following steps:

[0037] S1, dissolving cerium nitrate and phytic acid in a mixed solution (methanol to water volume ratio of 5:95) at a molar ratio of 0.5:1 to prepare a mixed solution;

[0038] S2, immersing the carbon cloth in the mixed solution and transferring it to a reactor lined with polytetrafluoroethylene, reacting at 160° C. for 24 hours, separating, washing with deionized water, and drying to constant weight to obtain a composite intermediate;

[0039] S3. In a three-electrode electrochemical system, the composite intermediate was added to an electrolyte solution (the molar ratio of nickel acetate, sodium hypophosphite, ammonium chloride and sodium chloride was 1:10:10:10), and the composite intermediate was taken out after 5 cycles at a voltage range of 0.1V-0.3V and a scanning rate of 6mV / s, washed with deionized water and dried at 70°C under vacuum for 5h to obtain a nickel-based composite electrocatalyst (Ni2P / CePO4 / CFC).

[0040] Comparative Example 1

[0041] This comparative example 1 provides a method for preparing a nickel-based composite electrocatalyst, comprising the following steps: in a three-electrode electrochemical system, adding carbon cloth as a cathode to an electrolyte solution (the molar ratio of nickel acetate, sodium hypophosphite, ammonium chloride, and sodium chloride is 1:10:10:10), cycling 5 times at a voltage range of 0.1V-0.3V and a scanning rate of 6mV / s, taking out the carbon cloth, washing it with deionized water, and drying it at 70°C under vacuum for 5h to obtain a nickel-based composite electrocatalyst (Ni2P / CFC).

[0042] Application Example 1

[0043] This application example 1 provides an electrocatalytic method using the nickel-based composite electrocatalyst prepared in Example 1, comprising: adding a nickel-based composite electrocatalyst with a specification of 1 cm×1 cm into a potassium hydroxide electrolyte solution with a concentration of 1 mol / L containing 20 mmol / L 5-hydroxymethylfurfural (HMF), using the nickel-based composite electrocatalyst as a working electrode, a platinum sheet as a counter electrode, and a Hg / HgO electrode as a reference electrode, and performing an electrocatalytic conversion reaction at a constant voltage of 1.4 V in a three-electrode electrochemical system at room temperature of 25°C for 2 hours. The reaction results are shown in Table 1 below.

[0044] Application Example 2

[0045] This application example 2 provides an electrocatalytic method using the nickel-based composite electrocatalyst prepared in Example 1, comprising: adding a nickel-based composite electrocatalyst with a specification of 1 cm×1 cm into a potassium hydroxide electrolyte solution with a concentration of 1 mol / L containing 20 mmol / L furfural (FAL), using the nickel-based composite electrocatalyst as a working electrode, a platinum sheet as a counter electrode, and a Hg / HgO electrode as a reference electrode, and performing an electrocatalytic conversion reaction at a constant voltage of 1.42 V in a three-electrode electrochemical system at room temperature of 25°C for 2 hours. The reaction results are shown in Table 1 below.

[0046] Application Example 3

[0047] This application example 3 provides an electrocatalytic method using the nickel-based composite electrocatalyst prepared in Example 1, comprising: adding a nickel-based composite electrocatalyst with a specification of 1 cm×1 cm into a potassium hydroxide electrolyte solution with a concentration of 1 mol / L containing 20 mmol / L 5-methylfurfural (5-MF), using the nickel-based composite electrocatalyst as a working electrode, a platinum sheet as a counter electrode, and a Hg / HgO electrode as a reference electrode, in a three-electrode electrochemical system at room temperature of 25°C, an electrocatalytic conversion reaction is carried out at a constant voltage of 1.45V, the reaction time is 2h, and the reaction results are shown in Table 1 below.

[0048] Application Example 4

[0049] This application example 4 provides an electrocatalytic method using the nickel-based composite electrocatalyst prepared in comparative example 1, comprising: adding a nickel-based composite electrocatalyst with a specification of 1 cm×1 cm into a potassium hydroxide electrolyte solution with a concentration of 1 mol / L containing 20 mmol / L 5-hydroxymethylfurfural (HMF), using the nickel-based composite electrocatalyst as a working electrode, a platinum sheet as a counter electrode, and a Hg / HgO electrode as a reference electrode, and performing an electrocatalytic conversion reaction at a constant voltage of 1.4 V in a three-electrode electrochemical system at room temperature of 25°C for 2 hours. The reaction results are shown in Table 1 below.

[0050] Table 1 Application example reaction results

[0051]

[0052] As can be seen from Table 1, the nickel-based composite electrocatalyst prepared in Comparative Example 1 is far inferior to that in Example 1 in terms of both FDCA yield and Faraday efficiency of FDCA, which can highlight the importance of introducing cerium phosphate. The introduction of cerium phosphate directly improves the performance of the catalyst for the electrocatalytic conversion of furanaldehyde represented by HMF electrocatalytic oxidation. The spherical nano-nickel-based electrocatalyst grown on the prepared cerium phosphate additive layer is applied to the electrocatalytic oxidation of HMF to produce FDCA with a yield of 99%, a Faraday efficiency of 95%, and a carbon balance of 99%.

[0053] The carbon cloth, the composite intermediate and the nickel-based composite electrocatalyst in Example 1 were characterized by scanning electron microscopy. Figure 2 As shown in A, B, and C. Figure 2 It can be seen that the cerium phosphate structure grows uniformly on the carbon cloth, and uniform nano-spherical structures are stacked on the surface of the cerium phosphate. The nickel-based composite electrocatalyst in Example 1 was characterized by high-power transmission electron microscopy. Figure 3As shown, it can be seen that diffraction fringes corresponding to Ni2P and CePO4 are found on the nickel-based composite electrocatalyst, confirming the crystal characteristics of the nickel-based composite electrocatalyst. In addition, a clear contact interface or phase interface between the two solid components can be found, indicating that Ni2P and CePO4 are in close contact with each other, further confirming the successful synthesis of the nickel-based composite electrocatalyst. The nickel-based composite electrocatalyst of Example 1 was subjected to 10 consecutive electrolysis reactions, as shown in FIG. Figure 4 As shown, the catalyst can still maintain more than 95% FDCA yield and more than 95% Faradaic efficiency after 10 consecutive cycles.

[0054] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A method for preparing a nickel-based composite electrocatalyst, characterized in that: include: Stirring and dissolving the metal nitrate and the phosphorus source to prepare a mixed solution; The carbon substrate is immersed in the mixed solution to undergo a solvothermal reaction and then separated to obtain a composite intermediate; The composite intermediate is electro-deposited in an electrolyte solution by cyclic voltammetry to obtain a nickel-based composite electrocatalyst; wherein nickel acetate, sodium hypophosphite, ammonium chloride and sodium chloride are dissolved in the electrolyte solution.

2. The preparation method according to claim 1, characterized in that: The metal nitrate includes one of rare earth nitrate, lithium nitrate, and strontium nitrate; and / or the phosphorus source includes one of sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, and phytic acid; and / or the carbon substrate includes one of carbon paper and carbon cloth.

3. The preparation method according to claim 1, characterized in that: The molar ratio of the metal nitrate to the phosphorus source in the mixed solution is (0.2-0.5):1; and / or the solvent in the mixed solution comprises a mixture of methanol and water, and the volume fraction of the methanol in the mixed solution is less than or equal to 5%.

4. The preparation method according to claim 1, characterized in that: The carbon substrate is immersed in the mixed solution, reacted at 150° C.-180° C. for 8 h-24 h, and then separated to obtain a composite intermediate; and / or, a solvent thermal reaction is performed, followed by separation, washing, and drying to obtain a composite intermediate.

5. The preparation method according to claim 1, characterized in that: The molar ratio of the nickel acetate, the sodium hypophosphite, ammonium chloride and sodium chloride in the electrolyte solution is 1:(5-15):(5-15):(5-15).

6. The preparation method according to claim 1, characterized in that: When the electrodeposition is performed by cyclic voltammetry, the electrodeposition is cycled 5 to 20 times at a voltage range of 0.1 V to 0.3 V and a scan rate of 2 mV / s to 10 mV / s.

7. The preparation method according to claim 1, characterized in that: The nickel-based composite electrocatalyst is prepared after washing after electrodeposition and drying at 60° C.-80° C.

8. A nickel-based composite electrocatalyst prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The invention comprises a carbon matrix and a phosphate auxiliary agent layer grown on the surface of the carbon matrix, and nickel-based nanoparticles are grown on the surface of the phosphate auxiliary agent layer.

9. Use of the nickel-based composite electrocatalyst prepared by the preparation method according to any one of claims 1 to 7 in an electrocatalytic reaction.

10. The use according to claim 9, characterized in that: The application includes the electrocatalytic oxidation of furan aldehyde biomass into furan carboxylic acid compounds.

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