Metal phosphide-three-dimensional porous graphene composite electro-catalytic material as well as preparation method and application thereof

Abstract

The invention discloses a metal phosphide-three-dimensional porous graphene composite electro-catalytic material and a preparation method and application thereof, and belongs to the technical field of composites.The method comprises the steps that 1, laser is used for irradiating a benzoxazine precursor, the benzoxazine precursor is a benzoxazine monomer or a cured product formed by crosslinking and curing the benzoxazine monomer, and the benzoxazine precursor is a metal phosphide-three-dimensional porous graphene composite electro-catalytic material; a three-dimensional porous graphene skeleton structure is obtained after irradiation; (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 carrying out electro-deposition in an electrolyte containing metal salt and hypophosphite to obtain a metal phosphide-three-dimensional porous graphene composite electro-catalytic material; the method is simple in process, the metal phosphide in the prepared composite electro-catalysis material is uniformly loaded on the surface of the pore wall of the graphene with the three-dimensional porous network structure, the porous structure is exposed, and the composite electro-catalysis material has excellent conductivity and shows extremely high application potential in the field of electro-catalysis.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and particularly relates to a metal phosphide-three-dimensional porous graphene composite electrocatalytic material, a preparation method thereof, and an application thereof. Background Art

[0002] Nowadays, the non-renewability of traditional fossil fuels has become increasingly prominent, and promoting the optimization of the energy structure towards clean, low-carbon and renewable directions has become a key breakthrough direction for technological innovation. As an efficient energy conversion method, electrocatalysis is considered to be one of the important ways to produce clean energy and high-value chemicals. Electrocatalysts are the core of electrocatalytic energy conversion and storage technologies (such as hydrogen production, preparation of high-value chemicals, etc.), and are crucial for accelerating reaction kinetics and thus improving the total energy conversion efficiency. Although noble metal catalysts exhibit high electrocatalytic activity, problems such as scarce reserves and high prices limit their applications. Non-noble metal catalysts (such as transition metal oxides) have cost advantages, but generally face problems such as easy inactivation of active sites and insufficient long-term operation stability. Developing new electrocatalysts with high efficiency, stability and low cost has always been the focus of attention in the academic and industrial fields.

[0003] The Chinese patent document with the publication number CN104415758A discloses a preparation method and application of a non-noble metal electrocatalyst. In this invention, a carbon carrier, an alkaline substance and an aqueous solution of a transition metal salt are mixed evenly; condensation reflux is carried out at 50-200 °C for more than 0.5 h to obtain a precipitate; suction filtration is carried out, and the precipitate is washed with water until neutral and then dried; heat treatment is carried out at 200-800 °C for 0.5-5 h in different atmospheres to obtain a non-noble metal electrocatalyst.

[0004] The Chinese patent document with the publication number CN103962139A discloses a preparation method and application of a graphene-supported non-noble metal electrocatalyst. In this invention, under heating conditions, a nitrogen-containing ligand and a metal salt are mixed to form a complex, and the formed complex is deposited on a graphene oxide carrier by cooling. A reducing agent is added to reduce the graphene oxide, and after washing, drying, heat treatment and pickling, a graphene-supported non-noble metal electrocatalyst is obtained, wherein the heat treatment conditions are calcination in a carrier gas at 400-1200 °C for 0.5-5 h.

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

[0006] To solve the deficiencies existing in the above-mentioned prior art, the present invention provides a method for preparing a metal phosphide-three-dimensional porous graphene composite electrocatalytic material. The process is simple, and in the prepared composite electrocatalytic material, the metal phosphide is uniformly loaded on the surface of the graphene pore wall with a three-dimensional porous network structure, showing 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, comprising:

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

[0010] (2) Using the obtained three-dimensional porous graphene skeleton structure as a working electrode, graphite carbon as a counter electrode, and Hg / HgO as a reference electrode, electro-depositing in an electrolyte solution comprising a metal salt and a 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. 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] The laser radiation generates a photothermal effect on the surface of the benzoxazine precursor, causing the chemical bonds therein to be broken, and the carbon atoms to rearrange to form graphene. At the same time, the gas products generated during this process lead to the formation of a three-dimensional porous structure, thereby preparing graphene with a three-dimensional porous network structure, which can be directly used as a working electrode. During the electro-deposition 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 mainly uniformly dispersed on the surface of the three-dimensional porous graphene pore wall in the form of dendritic crystals, and will also induce the uniform loading of the metal phosphide, exposing the porous structure.

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

[0014]

[0015] In formula (I): R 1 is -CH 2 -, -C(CH 3 ) 2 -, -C(CF 3 ) 2 - or -SO 2 -; R2 and R 3 are each independently selected from phenyl or 2-methylenefuran;

[0016]

[0017] In formula (II): R 1 is -CH 2 - or -SO 2 -; R 2 and R 3 are each independently selected from hydrogen or alkyl;

[0018] The benzoxazine monomer having the structure shown in formula (I) or formula (II) is crosslinked and cured at a temperature of 100 - 260 °C for 1 - 12 h to form a cured product.

[0019] Further, during the laser irradiation process, the laser used is a CO 2 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.

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

[0021] Further, the molar ratio of the 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] Further, the hypophosphite is sodium hypophosphite and / or potassium hypophosphite, and the concentration of the hypophosphite in the electrolyte is 10 - 200 mmol / L.

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

[0024] Further, the electrodeposition method is constant current deposition, the current density is 5 - 35 mA / cm 2 , and the deposition time is 5 - 60 min.

[0025] The present invention also provides a 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, the structure of which includes a graphene framework material having a three - dimensional porous network structure and the metal phosphide loaded thereon, wherein the metal phosphide is uniformly loaded on the pore walls of the graphene, and the components of the metal phosphide include but are not limited to NiCuP, CoCuP, MnCuP, FeCoNiCuP, etc.

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

[0027] The present invention also provides an application of the 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 the present invention, the preparation method of the three-dimensional porous graphene framework structure is simple, without the need for harsh conditions such as traditional high temperature and inert atmosphere. At the same time, through the electrodeposition step, the uniform loading of metal phosphide on the surface of the graphene pore wall can be realized. There are a large number of active sites, and the porous structure is exposed. The metal phosphide has high catalytic activity and good accessibility, so that the prepared composite electrocatalytic material has excellent electrical conductivity and shows excellent application potential in the field of electrocatalysis.

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

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

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

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

[0034] Figure 4 It is the SEM image of the NiP-three-dimensional porous graphene composite material prepared in Comparative Example 1 of the present invention;

[0035] Figure 5 It is the SEM image of the NiFeP-three-dimensional porous graphene composite material prepared in Comparative Example 3 of the present invention. Detailed Embodiments

[0036] To make the objectives, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description through specific embodiments. Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below. The technical features in various embodiments of the present invention can be combined accordingly without conflict.

[0037] For the operating methods without specific conditions noted in the following embodiments, they are generally in accordance with conventional conditions or the conditions recommended by the manufacturer. The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0038] Example 1

[0039] (1) Use CO 2 laser to irradiate the benzoxazine precursor (a cured product formed by crosslinking and curing the benzoxazine monomer shown below, curing temperature 220 °C, curing time 6 h). The laser power is 10 W, the scanning speed is 12.5 cm / s, and the defocus distance is 0 mm to obtain a three-dimensional porous graphene framework structure;

[0040]

[0041] (2) Weigh 0.7 mmol of NiSO 4 ·6H 2 O, 0.3 mmol of CuSO 4 ·5H 2 O and 1 mmol of NaH 2 PO 2 ·H 2 O and dissolve them in 100 mL of deionized water, stir evenly to obtain an electrolyte solution;

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

[0043] Figure 1 This is the SEM image of the three-dimensional porous graphene framework structure prepared in this example, and the porous structure can be clearly seen.

[0044] Figure 2SEM image of the NiCuP-3D porous graphene composite electrocatalytic material prepared in this example. As can be seen from the figure, NiCuP is uniformly dispersed on the pore wall surface of the 3D porous graphene, exposing the original porous framework structure.

[0045] The hydrogen evolution reaction (HER) activity of the NiCuP-3D porous graphene composite electrocatalytic material was further evaluated, with the 3D porous graphene framework structure as a control. The measurement was carried out in 1M KOH solution. As Figure 3 shown, the results indicate that it has efficient hydrogen evolution performance, with an overpotential of -190 mV at a current density of 10 mA cm -2 .

[0046] Example 2

[0047] (1) Use a CO 2 laser to irradiate the benzoxazine precursor (a cured product formed by cross-linking and curing the benzoxazine monomer shown below, curing temperature 150 °C, curing time 12 h), with a laser power of 5 W, a scanning speed of 7 cm / s, and a defocus distance of 0 mm, to obtain a 3D porous graphene framework structure;

[0048]

[0049] (2) Weigh 0.5 mmol of NiSO 4 ·6H 2 O, 0.5 mmol of CuSO 4 ·5H 2 O and 1.3 mmol of NaH 2 PO 2 ·H 2 O and dissolve them in 100 mL of deionized water, stir evenly to obtain an electrolyte solution;

[0050] (3) Use the 3D porous graphene framework structure obtained in step (1) as the working electrode, graphite carbon as the counter electrode, and Hg / HgO as the reference electrode, and perform constant current electrodeposition in the electrolyte solution of step (2), with a deposition current density of 20 mA / cm 2 , and a deposition time of 10 min to obtain the NiCuP-3D porous graphene composite electrocatalytic material.

[0051] In this NiCuP-three-dimensional porous graphene composite electrocatalytic material, NiCuP is uniformly dispersed on the pore wall surface of the three-dimensional porous graphene, and the original porous framework structure can be exposed. The application of this NiCuP-three-dimensional porous graphene composite material in the catalytic oxidation of 5-hydroxymethylfurfural (HMF) to prepare 2,5-furandicarboxylic acid was further evaluated. The measurement was carried out in a 1 mol / L KOH solution containing 50 mmol / L HMF. The conversion rate of 5-hydroxymethylfurfural was measured to be 99.7%, and the yield of 2,5-furandicarboxylic acid was 93.1%.

[0052] Example 3

[0053] (1) Use CO 2 Irradiate the benzoxazine precursor (a cured product formed by crosslinking and curing the benzoxazine monomer shown below, curing temperature 260 °C, curing time 5 h) with a CO laser, the laser power is 15 W, the scanning speed is 25 cm / s, and the defocus distance is 2 mm to obtain a three-dimensional porous graphene framework structure;

[0054]

[0055] (2) Weigh 10 mmol of Mn(CH 3 COO) 2 , 10 mmol of Cu(CH 3 COO) 2 and 20 mmol of NaH 2 PO 2 ·H 2 O and dissolve them in 100 mL of deionized water, stir evenly to obtain an electrolyte solution;

[0056] (3) Use the three-dimensional porous graphene framework structure obtained in step (1) as the working electrode, graphite carbon as the counter electrode, and Hg / HgO as the reference electrode, and perform constant current electrodeposition in the electrolyte solution of step (2), the deposition current density is 5 mA / cm 2 , and the deposition time is 60 min to obtain the MnCuP-three-dimensional porous graphene composite electrocatalytic material.

[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, and the original porous framework structure can be exposed.

[0058] Example 4

[0059] (1) Use CO 2 Irradiate the benzoxazine monomer (the structure is shown below) with a CO laser, the laser power is 7 W, the scanning speed is 25 cm / s, and the defocus distance is 4 mm to obtain a three-dimensional porous graphene framework structure;

[0060]

[0061] (2) Weigh 0.5 mmol of Co(NO 3 ) 2 ·6H 2 O, 0.5 mmol of CuCl 2 and 1 mmol of NaH 2 PO 2 ·H 2 O, dissolve them in 100 mL of deionized water, stir evenly to obtain an electrolyte solution;

[0062] (3) Use the three-dimensional porous graphene framework structure obtained in step (1) as the working electrode, graphite carbon as the counter electrode, and Hg / HgO as the reference electrode, and perform constant current electrodeposition in the electrolyte solution of step (2). The deposition current density is 35 mA / cm 2 , and the deposition time is 5 min to obtain the FeCuP-three-dimensional porous graphene composite electrocatalytic material.

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

[0064] Example 5

[0065] (1) Use a CO 2 laser to irradiate the benzoxazine monomer (the structure is shown below). The laser power is 5 W, the scanning speed is 19 cm / s, and the defocusing distance is 4 mm to obtain a three-dimensional porous graphene framework structure;

[0066]

[0067] (2) Weigh 0.2 mmol of FeCl 2 , 0.2 mmol of NiCl 2 , 0.2 mmol of CoCl 2 , 0.4 mmol of CuCl 2 and 1 mmol of NaH 2 PO 2 ·H 2 O, dissolve them in 100 mL of deionized water, stir evenly to obtain an electrolyte solution;

[0068] (3) Use the three-dimensional porous graphene framework structure obtained in step (1) as the working electrode, graphite carbon as the counter electrode, and Hg / HgO as the reference electrode, and perform constant current electrodeposition in the electrolyte solution of step (2). The deposition current density is 15 mA / cm 2, with a deposition time of 30 min, a 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, and the original porous skeleton structure can be exposed.

[0070] Comparative Example 1

[0071] The difference between this comparative example and Example 1 is only that: when preparing the electrolyte, CuSO 4 ·5H 2 O is not added, and 1 mmol of NiSO 4 ·6H 2 O and 1 mmol of NaH 2 PO 2 ·H 2 O are directly weighed and dissolved in 100 mL of deionized water, stirred evenly to obtain the electrolyte; the SEM image of the finally obtained NiP-three-dimensional porous graphene composite material is as Figure 4 shown. Obviously, NiP agglomerates seriously and covers the surface of the three-dimensional porous graphene material in layers, and the original porous structure cannot be observed.

[0072] Comparative Example 2

[0073] The difference between this comparative example and Example 1 is only that: when preparing the electrolyte, 0.98 mmol of NiSO 4 ·6H 2 O, 0.02 mmol of CuSO 4 ·5H 2 O and 1 mmol of NaH 2 PO 2 ·H 2 O are dissolved in 100 mL of deionized water, stirred evenly to obtain the electrolyte. In the obtained NiCuP-three-dimensional porous graphene composite material, NiCuP agglomerates seriously and covers the three-dimensional porous graphene surface in layers, and the original porous structure cannot be observed.

[0074] Comparative Example 3

[0075] The difference between this comparative example and Example 1 is only that: when preparing the electrolyte, CuSO 4 ·5H 2 O is replaced by FeSO 4 ·7H 2 O. The SEM image of the obtained NiFeP-three-dimensional porous graphene composite material is as Figure 5As shown in the figure, it can be seen that NiFeP is severely agglomerated and covered on the surface of the three-dimensional porous graphene in blocks, and the original porous structure cannot be observed.

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

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

Claims

1. A method for preparing a metal phosphide-three-dimensional porous graphene composite electrocatalytic material, characterized in that: include: (1) irradiating a benzoxazine precursor with a laser, wherein the benzoxazine precursor is a benzoxazine monomer or a solidified product formed by cross-linking and curing the benzoxazine monomer, and obtaining a three-dimensional porous graphene skeleton structure after irradiation; (2) using the obtained three-dimensional porous graphene skeleton structure as a working electrode, graphite carbon as a counter electrode, and Hg / HgO as a reference electrode, and performing electrodeposition in an electrolyte containing components including a metal salt and a hypophosphite 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 at least one of a nickel salt, an iron salt, a cobalt salt, a manganese salt, and a chromium salt.

2. The method for preparing the metal phosphide-three-dimensional porous graphene composite electrocatalytic material according to claim 1, characterized in that: The benzoxazine monomer has at least one of the structures shown in formula (I) and formula (II): 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; In formula (II): R1 is -CH2- or -SO2-; R2 and R3 are each independently selected from hydrogen or alkyl; The benzoxazine monomer with the structure represented by formula (I) or formula (II) is cross-linked and cured at a temperature of 100-260° C. for 1-12 hours to form a cured product.

3. The method for preparing 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 5-15W, the scanning speed is 7-25cm / s, and the defocus distance is 0-4mm.

4. The method for preparing the metal phosphide-three-dimensional porous graphene composite electrocatalytic material according to claim 1, characterized in that: The molar ratio of the metal elements in the first metal salt and the second metal salt is ≥0.5:9.

5.

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

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

3.

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

8. A metal phosphide-three-dimensional porous graphene composite electrocatalytic material prepared according to the method for preparing a metal phosphide-three-dimensional porous graphene composite electrocatalytic material according to any one of claims 1 to 7.

9. Use of the metal phosphide-three-dimensional porous graphene composite electrocatalytic material according to claim 8 in catalyzing the electrolysis of water to produce hydrogen.

10. Use of the metal phosphide-three-dimensional porous graphene composite electrocatalytic material according to claim 8 in catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid.

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