Metal phosphide-three-dimensional porous graphene composite electrocatalytic material and preparation method and application thereof

Abstract

The application discloses a metal phosphide-three-dimensional porous graphene composite electrocatalytic material and a preparation method and application thereof, and belongs to the technical field of composite materials. The method comprises the following steps: (1) irradiating a benzoxazine precursor by using a laser, wherein the benzoxazine precursor is a benzoxazine monomer or a solidified product formed by cross-linking and solidification of the benzoxazine monomer, and a three-dimensional porous graphene skeleton structure is obtained after irradiation; and (2) taking the three-dimensional porous graphene skeleton structure as a working electrode, taking graphite carbon as a counter electrode, taking Hg / HgO as a reference electrode, and performing electrodeposition in an electrolyte solution comprising a metal salt and hypophosphite to obtain the metal phosphide-three-dimensional porous graphene composite electrocatalytic material. The method is simple in process, the metal phosphide in the prepared composite electrocatalytic material is uniformly loaded on the graphene pore wall surface with a three-dimensional porous network structure, the porous structure is exposed, excellent electric conductivity is achieved, and the composite electrocatalytic material exhibits extremely high application potential in the field of electrocatalysis.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to a metal phosphide-three-dimensional porous graphene composite electrocatalytic material, its preparation method, and its application. Background Technology

[0002] With the increasing non-renewability of traditional fossil fuels, optimizing the energy structure towards clean, low-carbon, and renewable sources has become a key area for technological innovation. Electrocatalysis, as a highly efficient energy conversion method, is considered one of the important pathways for producing clean energy and high-value-added chemicals. Electrocatalysts are the core of electrocatalytic energy conversion and storage technologies (such as hydrogen production and high-value chemical preparation), and are crucial for accelerating reaction kinetics and thus improving overall energy conversion efficiency. Although noble metal catalysts exhibit highly efficient electrocatalytic activity, their application is limited by their scarcity and high price. Non-noble metal catalysts (such as transition metal oxides), while possessing cost advantages, generally face problems such as easy deactivation of active sites and insufficient long-term operational stability. Developing novel, efficient, stable, and low-cost electrocatalysts has always been a focus of attention for both academia and industry.

[0003] Chinese patent document CN104415758A discloses a method for preparing and applying a non-precious metal electrocatalyst. The invention involves uniformly mixing a carbon support, an alkaline substance, and an aqueous solution of a transition metal salt; refluxing at 50-200°C for more than 0.5 hours to obtain a precipitate; filtering, washing the precipitate with water until neutral, and drying; and heat-treating at 200-800°C for 0.5-5 hours in different atmospheres to obtain the non-precious metal electrocatalyst.

[0004] Chinese patent document CN103962139A discloses a method for preparing and applying a graphene-supported non-precious metal electrocatalyst. In this invention, under heating conditions, a nitrogen-containing ligand is mixed with a metal salt to form a complex. The complex is then deposited on a graphene oxide support by cooling. A reducing agent is added to reduce the graphene oxide. After washing, drying, heat treatment, and acid washing, the graphene-supported non-precious metal electrocatalyst is obtained. The heat treatment conditions are calcination in a carrier gas at 400-1200℃ for 0.5-5 hours.

[0005] The preparation process of the aforementioned non-precious metal electrocatalysts usually requires harsh conditions such as high temperature and inert atmosphere, and there may be problems with uneven loading of active components on carbon materials. Therefore, there is an urgent need to develop an electrocatalytic material with good catalytic performance, uniform loading of active components, good conductivity, and good prospects for industrial production. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, this invention provides a method for preparing a metal phosphide-three-dimensional porous graphene composite electrocatalytic material. The process is simple, and the resulting composite electrocatalytic material has metal phosphides uniformly loaded on the pore wall surface of graphene with a three-dimensional porous network structure, exhibiting extremely high application potential in the field of electrocatalysis.

[0007] The specific technical solution adopted is as follows:

[0008] A method for preparing a metal phosphide-three-dimensional porous graphene composite electrocatalytic material includes:

[0009] (1) Irradiate the benzoxazine precursor with a laser. The benzoxazine precursor is a benzoxazine monomer or a cured product formed by cross-linking and curing of benzoxazine monomer. After irradiation, a three-dimensional porous graphene framework structure is obtained.

[0010] (2) The obtained three-dimensional porous graphene framework structure was used as the working electrode, with graphite carbon as the counter electrode and Hg / HgO as the reference electrode. Electrodeposition was carried out in an electrolyte containing metal salt and hypophosphite to obtain a metal phosphide-three-dimensional porous graphene composite electrocatalytic material.

[0011] The metal salt includes a first metal salt and a second metal salt, wherein the first metal salt is a copper salt and the second metal salt is at least one of a nickel salt, an iron salt, a cobalt salt, a manganese salt, and a chromium salt.

[0012] Laser radiation generates a photothermal effect on the surface of the benzoxazine precursor, which breaks the chemical bonds and rearranges the carbon atoms to form graphene. At the same time, the gaseous products generated in this process lead to the formation of a three-dimensional porous structure, thus preparing graphene with a three-dimensional porous network structure, which can be used directly as a working electrode. During the electrodeposition process, the deposition potential of copper is higher than that of other metals such as iron, nickel, cobalt, manganese, and chromium. The final deposition morphology will be mainly dominated by copper. Copper is uniformly dispersed on the surface of the three-dimensional porous graphene pore walls in the form of dendritic crystals, which will also induce the metal phosphide to achieve uniform loading and expose the porous structure.

[0013] Furthermore, the benzoxazine monomer has at least one of the structures shown in formula (I) and formula (II):

[0014]

[0015] In formula (I): R1 is one of -CH2-, -C(CH3)2-, -C(CF3)2- or -SO2-; R2 and R3 are each independently selected from phenyl or 2-methylenefuran;

[0016]

[0017] In formula (II): R1 is -CH2- or -SO2-; R2 and R3 are each independently selected from hydrogen or alkyl groups;

[0018] The benzoxazine monomers with the structure shown in formula (I) or formula (II) are cross-linked and cured at a temperature of 100-260℃ for 1-12 hours to form a cured product.

[0019] Furthermore, during the laser irradiation process, a CO2 light source is used, with a laser power of 5-15W, a scanning speed of 7-25cm / s, and a defocusing distance of 0-4mm.

[0020] Furthermore, the metal salt can be selected from metal sulfates, nitrates, acetates, hydrochlorides, etc.

[0021] Furthermore, the molar ratio of metal elements in the first metal salt and the second metal salt is ≥0.5:9.5, preferably in the range of 1:1-4.

[0022] Furthermore, the hypophosphite is sodium hypophosphite and / or potassium hypophosphite, and the concentration of hypophosphite in the electrolyte is 10-200 mmol / L.

[0023] Preferably, in the electrolyte, the molar ratio of the metal element in the metal salt to the phosphorus element in the hypophosphite is 1:1-1.3.

[0024] Furthermore, the electrodeposition method is constant current deposition, with a current density of 5-35 mA / cm². 2 The deposition time is 5-60 minutes.

[0025] The present invention also provides a method for preparing the metal phosphide-three-dimensional porous graphene composite electrocatalytic material, wherein the metal phosphide-three-dimensional porous graphene composite electrocatalytic material comprises a graphene framework material having a three-dimensional porous network structure and metal phosphides loaded on it, wherein the metal phosphides are uniformly loaded on the pore walls of the graphene, and the components of the metal phosphides include, but are not limited to, NiCuP, CoCuP, MnCuP, FeCoNiCuP, etc.

[0026] This invention also provides the application of the aforementioned metal phosphide-three-dimensional porous graphene composite electrocatalytic material in the catalytic water electrolysis hydrogen removal reaction.

[0027] This invention also provides the application of the aforementioned metal phosphide-three-dimensional porous graphene composite electrocatalytic material in the catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) In this invention, the preparation method of the three-dimensional porous graphene framework structure is simple and does not require harsh conditions such as traditional high temperature and inert atmosphere. At the same time, the metal phosphide can be uniformly loaded on the surface of the graphene pore wall through the electrodeposition step, with a large number of active sites and exposed porous structure. The metal phosphide has high catalytic activity and good accessibility, so the prepared composite electrocatalytic material has excellent conductivity and shows great application potential in the field of electrocatalysis.

[0030] (2) The present invention provides a metal phosphide-three-dimensional porous graphene composite electrocatalytic material that can be directly used as a self-supporting catalytic electrode, which is convenient to use and avoids the cumbersome and complicated electrode preparation steps of traditional powder electrocatalytic materials. Attached Figure Description

[0031] Figure 1 This is a SEM image of the three-dimensional porous graphene framework structure prepared in Example 1 of the present invention;

[0032] Figure 2 This is a SEM image of the NiCuP-three-dimensional porous graphene composite electrocatalytic material prepared in Example 1 of this invention;

[0033] Figure 3 The LSV curve of the NiCuP-three-dimensional porous graphene composite electrocatalytic material prepared in Example 1 of this invention in an alkaline aqueous solution;

[0034] Figure 4 This is a SEM image of the NiP-three-dimensional porous graphene composite material prepared in Comparative Example 1 of this invention.

[0035] Figure 5 This is a SEM image of the NiFeP-three-dimensional porous graphene composite material prepared in Comparative Example 3 of this invention. Detailed Implementation

[0036] To make the objectives, features, and advantages of this invention more apparent and understandable, a detailed description is provided below through specific embodiments. Many specific details are set forth in the following description to provide a thorough understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the invention can be combined appropriately without mutual conflict.

[0037] The operating methods described in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Contents not described in detail in this specification are prior art known to those skilled in the art.

[0038] Example 1

[0039] (1) The benzoxazine precursor (the cured product formed by cross-linking and curing of the benzoxazine monomer shown below, with a curing temperature of 220℃ and a curing time of 6h) was irradiated with a CO2 laser. The laser power was 10W, the scanning speed was 12.5cm / s, and the defocusing distance was 0mm to obtain a three-dimensional porous graphene framework structure.

[0040]

[0041] (2) Weigh 0.7 mmol of NiSO4·6H2O, 0.3 mmol of CuSO4·5H2O and 1 mmol of NaH2PO2·H2O and dissolve them in 100 mL of deionized water. Stir well to obtain the electrolyte.

[0042] (3) Using the three-dimensional porous graphene framework structure obtained in step (1) as the working electrode, with graphite carbon as the counter electrode and Hg / HgO as the reference electrode, constant current electrodeposition is performed in the electrolyte of step (2) at a deposition current density of 20 mA / cm². 2 The deposition time was 10 min, and NiCuP-three-dimensional porous graphene composite electrocatalytic material was obtained.

[0043] Figure 1 The SEM image of the three-dimensional porous graphene framework structure prepared in this embodiment clearly shows the porous structure.

[0044] Figure 2 This is a SEM image of the NiCuP-three-dimensional porous graphene composite electrocatalytic material prepared in this embodiment. As can be seen from the image, NiCuP is uniformly dispersed on the pore wall surface of the three-dimensional porous graphene, exposing the original porous framework structure.

[0045] The hydrogen evolution reaction (HER) activity of this NiCuP-three-dimensional porous graphene composite electrocatalyst was further evaluated, using a three-dimensional porous graphene framework structure as a control. Measurements were performed in 1M KOH solution. Figure 3 As shown in the figure, the results indicate that it has efficient hydrogen evolution performance with a current density of 10 mA cm⁻¹. -2 At that time, the overpotential was -190mV.

[0046] Example 2

[0047] (1) The benzoxazine precursor (the cured product formed by cross-linking and curing of the benzoxazine monomer shown below, with a curing temperature of 150℃ and a curing time of 12h) was irradiated with a CO2 laser. The laser power was 5W, the scanning speed was 7cm / s, and the defocusing distance was 0mm to obtain a three-dimensional porous graphene framework structure.

[0048]

[0049] (2) Weigh 0.5 mmol of NiSO4·6H2O, 0.5 mmol of CuSO4·5H2O and 1.3 mmol of NaH2PO2·H2O and dissolve them in 100 mL of deionized water. Stir well to obtain the electrolyte.

[0050] (3) Using the three-dimensional porous graphene framework structure obtained in step (1) as the working electrode, with graphite carbon as the counter electrode and Hg / HgO as the reference electrode, constant current electrodeposition is performed in the electrolyte of step (2) at a deposition current density of 20 mA / cm². 2 The deposition time was 10 min, and NiCuP-three-dimensional porous graphene composite electrocatalytic material was obtained.

[0051] This NiCuP-three-dimensional porous graphene composite electrocatalyst material, in which NiCuP is uniformly dispersed on the pore walls of three-dimensional porous graphene, exposes the original porous framework structure. The application of this NiCuP-three-dimensional porous graphene composite material in the catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid was further evaluated. Measurements were performed in a 1 mol / L KOH solution containing 50 mmol / L HMF. The conversion rate of 5-hydroxymethylfurfural was found to be 99.7%, and the yield of 2,5-furandicarboxylic acid was 93.1%.

[0052] Example 3

[0053] (1) The benzoxazine precursor (the cured product formed by cross-linking and curing of the benzoxazine monomer shown below, with a curing temperature of 260℃ and a curing time of 5h) was irradiated with a CO2 laser. The laser power was 15W, the scanning speed was 25cm / s, and the defocusing distance was 2mm to obtain a three-dimensional porous graphene framework structure.

[0054]

[0055] (2) Weigh 10 mmol of Mn(CH3COO)2, 10 mmol of Cu(CH3COO)2 and 20 mmol of NaH2PO2·H2O and dissolve them in 100 mL of deionized water. Stir well to obtain the electrolyte.

[0056] (3) Using the three-dimensional porous graphene framework structure obtained in step (1) as the working electrode, with graphite carbon as the counter electrode and Hg / HgO as the reference electrode, constant current electrodeposition is performed in the electrolyte of step (2) at a deposition current density of 5 mA / cm². 2 The deposition time was 60 min, and a MnCuP-three-dimensional porous graphene composite electrocatalytic material was obtained.

[0057] In this MnCuP-three-dimensional porous graphene composite electrocatalytic material, MnCuP is uniformly dispersed on the pore wall surface of the three-dimensional porous graphene, which can expose the original porous framework structure.

[0058] Example 4

[0059] (1) Irradiate the benzoxazine monomer (structure shown below) with CO2 laser. The laser power is 7W, the scanning speed is 25cm / s, and the defocusing distance is 4mm to obtain a three-dimensional porous graphene framework structure.

[0060]

[0061] (2) Weigh 0.5 mmol of Co(NO3)2·6H2O, 0.5 mmol of CuCl2 and 1 mmol of NaH2PO2·H2O and dissolve them in 100 mL of deionized water. Stir well to obtain the electrolyte.

[0062] (3) Using the three-dimensional porous graphene framework structure obtained in step (1) as the working electrode, with graphite carbon as the counter electrode and Hg / HgO as the reference electrode, constant current electrodeposition is performed in the electrolyte of step (2) at a deposition current density of 35 mA / cm². 2 The deposition time was 5 min, and FeCuP-three-dimensional porous graphene composite electrocatalytic material was obtained.

[0063] In this FeCuP-three-dimensional porous graphene composite electrocatalytic material, CoCuP is uniformly dispersed on the pore wall surface of the three-dimensional porous graphene, which can expose the original porous framework structure.

[0064] Example 5

[0065] (1) The benzoxazine monomer (structure shown below) was irradiated with a CO2 laser with a laser power of 5W, a scanning speed of 19cm / s, and a defocusing distance of 4mm to obtain a three-dimensional porous graphene framework structure.

[0066]

[0067] (2) Weigh 0.2 mmol of FeCl2, 0.2 mmol of NiCl2, 0.2 mmol of CoCl2, 0.4 mmol of CuCl2 and 1 mmol of NaH2PO2·H2O and dissolve them in 100 mL of deionized water. Stir well to obtain the electrolyte.

[0068] (3) Using the three-dimensional porous graphene framework structure obtained in step (1) as the working electrode, with graphite carbon as the counter electrode and Hg / HgO as the reference electrode, constant current electrodeposition is performed in the electrolyte of step (2) at a deposition current density of 15 mA / cm².2 The deposition time was 30 min, and FeCoNiCuP-three-dimensional porous graphene composite electrocatalytic material was obtained.

[0069] In this FeCoNiCuP-three-dimensional porous graphene composite electrocatalytic material, FeCoNiCuP is uniformly dispersed on the pore wall surface of the three-dimensional porous graphene, which can expose the original porous framework structure.

[0070] Comparative Example 1

[0071] The only difference between this comparative example and Example 1 is that, in preparing the electrolyte, CuSO4·5H2O was not added; instead, 1 mmol of NiSO4·6H2O and 1 mmol of NaH2PO2·H2O were directly weighed and dissolved in 100 mL of deionized water, and stirred until homogeneous to obtain the electrolyte. The final SEM image of the NiP-three-dimensional porous graphene composite material is shown below. Figure 4 As shown, it is obvious that NiP is severely aggregated and covers the surface of the three-dimensional porous graphene material in a layered manner, and the original porous structure cannot be observed.

[0072] Comparative Example 2

[0073] The only difference between this comparative example and Example 1 is that, when preparing the electrolyte, 0.98 mmol of NiSO4·6H2O, 0.02 mmol of CuSO4·5H2O and 1 mmol of NaH2PO2·H2O were weighed and dissolved in 100 mL of deionized water, stirred evenly, and the electrolyte was obtained. In the resulting NiCuP-three-dimensional porous graphene composite material, NiCuP was severely agglomerated and covered the surface of the three-dimensional porous graphene in a layered manner, and the original porous structure could not be observed.

[0074] Comparative Example 3

[0075] The only difference between this comparative example and Example 1 is that CuSO4·5H2O was replaced with FeSO4·7H2O when preparing the electrolyte. The SEM image of the obtained NiFeP-three-dimensional porous graphene composite material is shown below. Figure 5 As shown, NiFeP is severely aggregated, forming a blocky structure covering the surface of the three-dimensional porous graphene, and the original porous structure cannot be observed.

[0076] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0077] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A preparation method of a metal phosphide-three-dimensional porous graphene composite electrocatalytic material, characterized in that, The preparation method comprises the following steps: (1) irradiating a benzoxazine precursor by a laser, wherein the benzoxazine precursor is a benzoxazine monomer or a cured product formed by cross-linking and curing of the benzoxazine monomer, and a three-dimensional porous graphene skeleton structure is obtained after irradiation; (2) taking the three-dimensional porous graphene skeleton structure obtained in the step (1) as a working electrode, taking graphite carbon as a counter electrode, and taking Hg / HgO as a reference electrode, and performing electrodeposition in an electrolyte solution comprising a metal salt and a hypophosphite salt to obtain a metal phosphide-three-dimensional porous graphene composite electrocatalytic material; The metal salt comprises a first metal salt and a second metal salt, the first metal salt is a copper salt, and the second metal salt is a nickel salt; The benzoxazine monomer has at least one of structures shown in the following formula (I) and formula (II): ； The formula (I) is as follows: In the formula (I), R1 is one of -CH2-, -C(CH3)2-, -C(CF3)2- or -SO2-; and R2 and R3 are each independently selected from a phenyl group or a 2-methylene furan; ； The formula (II) is as follows: In the formula (II), R1 is -CH2- or -SO2-; and R2 and R3 are each independently selected from hydrogen or an alkyl group; The benzoxazine monomer having the structure shown in the formula (I) or formula (II) is cross-linked and cured at a temperature of 100-260 ℃ for 1-12 h to form a cured product; The molar ratio of metal elements in the first metal salt and the second metal salt is greater than or equal to 0.5:9.

5.

2. The preparation method of the metal phosphide-three-dimensional porous graphene composite electrocatalytic material according to claim 1, characterized in that, During the laser irradiation process, the laser used is a CO2 light source, the laser power is 5-15 W, the scanning speed is 7-25 cm / s, and the defocusing distance is 0-4 mm.

3. The preparation method of the metal phosphide-three-dimensional porous graphene composite electrocatalytic material according to claim 1, characterized in that, The hypophosphite salt is sodium hypophosphite and / or potassium hypophosphite, and the concentration of the hypophosphite salt in the electrolyte solution is 10-200 mmol / L.

4. The preparation method of the metal phosphide-three-dimensional porous graphene composite electrocatalytic material according to claim 1, characterized in that, In the electrolyte solution, the molar ratio of metal elements in the metal salt to phosphorus elements in the hypophosphite salt is 1:1-1.

3.

5. The preparation method of the metal phosphide-three-dimensional porous graphene composite electrocatalytic material according to claim 1, characterized in that, The electrodeposition mode is constant current deposition, the current density is 5-35 mA / cm 2 , and the deposition time is 5-60 min.

6. The metal phosphide-three-dimensional porous graphene composite electrocatalytic material prepared by the preparation method of the metal phosphide-three-dimensional porous graphene composite electrocatalytic material according to any one of claims 1-5.

7. Application of the metal phosphide-three-dimensional porous graphene composite electrocatalytic material according to claim 6 in catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furan dicarboxylic acid.

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