Nano-copper particle loaded nitrogen hybridized graphene catalyst and preparation method thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a nano-copper particle loaded nitrogen-hybridized graphene catalyst and a preparation method thereof.The catalyst is formed by compounding flaky graphene and flaky copper foil under the anchoring action of N nitrogen atoms, nano-graphene particles are deposited on the flaky copper foil, and the nano-copper particle loaded nitrogen-hybridized graphene catalyst is obtained. The nano-particles generated by the sheet-shaped copper foil are uniformly loaded on the surface of the sheet-shaped graphene. The nitrogen-hybridized graphene catalyst loaded with the nano-copper particles, which is prepared by the preparation method disclosed by the invention, has the advantages of high catalytic activity and strong stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and in particular relates to a nitrogen-hybridized graphene catalyst loaded with nano-copper particles and a preparation method thereof. Background Art

[0002] In the field of electrocatalysis, electrocatalysts can be divided into two major categories according to their components: metal and non-metal. Among them, metal catalysts have high catalytic activity and antibacterial properties, but their application is limited by their high cost and poor salt tolerance. Among non-metallic catalysts, graphene has the highest electrocatalytic activity and salt tolerance, but graphene has poor antibacterial properties and is prone to inactivation caused by microbial clogging during application. Therefore, in order to give full play to the complementary advantages of metal and non-metal graphene catalysts, the development of metal / graphene composite materials is an effective way to improve the catalytic activity, antibacterial properties and salt tolerance of electrocatalysts. However, the huge differences in the physical and chemical properties of metals and graphene lead to the following difficulties in realizing the complementary advantages of composite materials:

[0003] (1) Weak interfacial affinity: The surface tension of metal is about 500-1500 mN / m, while the surface tension of graphene is 45.3 mN / m. The huge difference in surface tension makes the interfacial bonding between metal and graphene difficult, and it is easy to peel off and fall off during use;

[0004] (2) Graphene is easy to agglomerate: When dispersed in solid form, graphene usually aggregates into flocs and is extremely difficult to disperse. Conventional graphene with less than 10 layers has serious agglomeration. Therefore, graphene is usually dispersed in liquid phase and there is a phenomenon of coagulation. In composite catalysts, if the graphene dispersion does not meet the requirements, the basis for the uniform dispersion of metal materials on the graphene surface will be lost;

[0005] (3) Poor metal dispersion: Due to the Pauli repulsion between the p electrons of graphene and the s electrons of the metal outer layer, it is difficult for the metal to be evenly dispersed on the graphene surface and it will spontaneously condense into large metal particles, resulting in a loss of metal single atom utilization in the composite material.

[0006] At present, the main effective preparation method to overcome the weak metal / graphene interface affinity, easy agglomeration of graphene, and poor metal dispersion is the anchoring method, which introduces inorganic heteroatoms as metal anchoring centers outside the graphene sheet structure and uses the formed MOC and MNC bonds to strengthen the metal / graphene interface affinity. Theoretically, in order to improve the metal / graphene interface affinity, there should be a large number of negatively charged atoms on the GNE surface as metal binding sites. The doping of heteroatoms with stronger electronegativity than C atoms can effectively increase the number of positively charged C atoms around the heteroatoms. In addition to gaseous atoms, atoms with stronger electronegativity than C atoms include F, Cl, Br, I, N, O, and S. Among them, N atoms can be doped into the six-membered ring structure of graphene to form a negative center. Therefore, N atoms can be used to modify graphene to provide basic binding sites for metal / graphene composites, and then the anchoring and dispersion effects of N nitrogen atoms in the hybrid graphene structure can be used to effectively enhance the metal / graphene interface affinity and improve the metal loading state.

[0007] Therefore, the development of a nitrogen-hybridized graphene catalyst loaded with nano-copper particles and its preparation method is of great significance for giving full play to the synergistic and complementary advantages of metal and non-metal catalysts. Summary of the Invention

[0008] The purpose of the present invention is to provide a nitrogen-hybridized graphene catalyst loaded with nano-copper particles and a preparation method thereof in response to the above-mentioned technical problems.

[0009] In view of this, the present invention provides a nitrogen-hybridized graphene catalyst carrying nano-copper particles. The catalyst is composited by flaky graphene and flaky copper foil under the anchoring effect of nitrogen atoms. Nano-graphene particles are deposited on the flaky copper foil, and the nanoparticles produced by the flaky copper foil are uniformly loaded on the surface of the flaky graphene.

[0010] Furthermore, the nano-graphene particles form a discontinuous graphene layer on the surface of the flaky copper foil.

[0011] Furthermore, the coverage rate of the surface of the sheet-like copper foil covered by the nano-graphene particles is ≤30%.

[0012] Furthermore, the average particle size of the graphene flakes is 100 to 500 nm, and the average particle size of the nanoparticles supported on the surface of the graphene flakes and generated by the copper foil flakes is less than 50 nm.

[0013] Furthermore, the sheet-like copper foil is a copper foil with a porous structure, and at least part of the nanographene particles are deposited inside the porous structure of the sheet-like copper foil.

[0014] Furthermore, the sheet copper foil is a metal copper foil with a (110) or (100) crystal plane preferential orientation.

[0015] A method for preparing a nitrogen-hybridized graphene catalyst loaded with nano-copper particles, the method being used to prepare the above-mentioned nitrogen-hybridized graphene catalyst loaded with nano-copper particles, the method comprising the steps of:

[0016] S1, copper foil pretreatment: After cleaning the copper foil, the flame formed by the combustion of combustible gas is sprayed onto the surface of the copper foil for segmented ablation. After the ablation is completed, the copper foil is cleaned again to obtain the ablated copper foil; then a discontinuous graphene layer is deposited on the surface of the copper foil using chemical vapor deposition, and then the copper foil is cut into 0.5 cm 2 The sheet-shaped copper foil is obtained as follows and set aside;

[0017] S2, preparation of graphene: weigh the raw materials according to the raw material component ratio: 30-50 parts by weight of graphite powder, 0.3-1 part by weight of sodium nitrate, 1.3-2.5 parts by weight of potassium permanganate, 3-6 parts by weight of concentrated sulfuric acid, 6-8 parts by weight of nitrite, 4-10 parts by weight of hydrogen peroxide, and 15-35 parts of water; then mix the concentrated sulfuric acid, graphite powder, sodium nitrate and water in an ice bath, then add potassium permanganate, and react under stirring for 1-2 hours, then heat the resulting mixture to 95-105° C. in an oil bath and continue to react for 0.6-1 hour; after the reaction is completed, add hydrogen peroxide, stir evenly, add the formulated amount of nitrite, and react at a pressure of 3-6 MPa and a temperature of 150-180° C. for 5-10 hours to obtain a flake graphene dispersion for later use;

[0018] S3, preparation of the catalyst: the flaky graphene dispersion prepared in the above step S2, 20 to 40 parts by weight of the nitrogen precursor, and 3 to 5 parts by weight of the pretreated flaky copper foil obtained in the above step S1 are mixed at room temperature, stirred evenly, and dried, and then placed in a closed reactor. First, the reaction is carried out at normal pressure and 450 to 550° C. for 2 to 2.5 hours, and then the pressure is increased to 0.5 to 3 MPa and maintained at this pressure for 1 to 5 minutes. The pressure relief valve is then quickly opened to instantly reduce the pressure in the reactor to normal pressure. The above pressure increase and pressure reduction process is then repeated 5 to 10 times. Then, the reactor is heated to 650 to 750° C. and the reaction is continued for 1 to 2 hours to obtain the nitrogen-hybridized graphene catalyst loaded with nano-copper particles.

[0019] Furthermore, in step S1, the copper foil surface is ablated using a 2-4 segmented ablation process. During the ablation process, the ablation temperature gradually increases with the increase in the number of ablation segments, and the ablation time for each segment is 2-5 minutes.

[0020] Furthermore, during the first ablation treatment, the flame temperature is 400-500°C; during the second ablation treatment, the flame temperature is 550-650°C; during the third ablation treatment, the flame temperature is 650-700°C; during the fourth ablation treatment, the flame temperature is 700-800°C, and the interval between each ablation treatment is 1-3 minutes.

[0021] Furthermore, the chemical vapor deposition process in step S1 is as follows:

[0022] First, a reducing gas is introduced into a reactor filled with inert gas and heated to 550-700° C., and then a carbon source gas and a reducing gas are pulsed and alternately introduced at 550-700° C.; wherein, the carbon source gas is introduced for 0.1-0.3 s, the residence time is 5-30 s, and the purge time is 10-20 s; the reducing gas is introduced for 0.1-0.3 s, the residence time is 10-20 s, the purge time is 10-20 s, and the pulse alternation cycle number is 300-800 times.

[0023] The present invention has the following beneficial effects: in the nano-copper particle-loaded nitrogen-hybridized graphene catalyst described in the present invention, the deposition of nano-graphene particles on the flaky copper foil increases the surface roughness of the flaky copper foil, enhancing the adhesion / occlusion between the copper foil and the flaky graphene, thereby helping to form a more stable and firm bonding interface between the two during the composite process; and, further, the deposition of nano-graphene particles changes the physical and chemical properties of the flaky copper foil surface, increasing the surface energy of the flaky copper foil, making the two more physically compatible, facilitating the spreading and adhesion of the flaky copper foil on the surface of the flaky graphene, and enhancing the interaction between the flaky copper foil and the flaky graphene, thereby improving the efficiency and stability of the composite. Ultimately, a metal / graphene composite catalyst material with high catalytic activity and strong stability is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the surface structure of the copper foil after segmented ablation treatment in the present invention;

[0025] Figure 2 Schematic diagram of the cross-sectional structure of the copper foil after chemical vapor deposition in the present invention;

[0026] Figure 3 is a transmission electron microscope photograph of the catalyst prepared in Example 1 of the present invention;

[0027] Figure 4 This is an X-ray photoelectron spectrometer analysis chart of the catalyst prepared in Example 1 of the present invention;

[0028] Figure 5 This is a diagram showing the effect of the catalyst obtained in Test Example 3 of the present invention on the degradation of acetaminophen;

[0029] Figure 6 This is a diagram showing the effect of the catalyst obtained in Test Example 3 of the present invention on the degradation of tetracycline hydrochloride;

[0030] The marks in the figure are:

[0031] 1. Sheet copper foil; 2. Porous structure; 3. Nanographene particles. DETAILED DESCRIPTION

[0032] The following will be combined with the accompanying drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0033] It should be noted that, in the present application, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the opposite order according to the functions involved. For example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0034] A nitrogen-hybridized graphene catalyst loaded with nano-copper particles is provided. The catalyst is composited by flaky graphene and flaky copper foil under the anchoring effect of nitrogen atoms. Nano-graphene particles are deposited on the flaky copper foil, and the nano-particles generated by the flaky copper foil are uniformly loaded on the surface of the flaky graphene.

[0035] In the nano-copper particle-loaded nitrogen-hybridized graphene catalyst described in the present invention, the deposition of nano-graphene particles on the flaky copper foil increases the surface roughness of the flaky copper foil, enhancing the adhesion / occlusion between the copper foil and the flaky graphene, and helping to form a more stable and firm bonding interface between the two during the composite process. Furthermore, the deposition of nano-graphene particles changes the physical and chemical properties of the flaky copper foil surface, increasing its surface energy, making it easier for the two to adapt to each other in terms of physical structure, facilitating the spreading and adhesion of the flaky copper foil on the surface of the flaky graphene, and enhancing the interaction between the flaky copper foil and the flaky graphene, thereby improving the efficiency and stability of the composite. Therefore, in the present invention, the deposited nano-graphene particles can act as a "bridge" to promote close contact and bonding between the flaky graphene and the copper foil.

[0036] In addition, the method of preparing the catalyst by composite of flaky graphene and flaky copper foil adopted in the present invention can reduce the loss of metal atom utilization caused by particle stacking, so that the graphene material after copper particle loading has more uniform metal active centers, improves the utilization of metal active sites, helps to improve the stability and catalytic activity of metal-non-metal composite catalysts, and has a good promoting effect on broadening the application of metal-non-metal composite catalysts.

[0037] Furthermore, the nano-graphene particles form a discontinuous graphene layer on the surface of the flaky copper foil.

[0038] Preferably, the coverage rate of the surface of the sheet-like copper foil covered by the nano-graphene particles is ≤30%.

[0039] More preferably, the coverage rate of the surface of the sheet-like copper foil covered by the nano-graphene particles is between 8% and 20%.

[0040] Maintaining the coverage of nanographene particles at an appropriate level can not only promote close contact and bonding between flake graphene and copper foil through the bridging effect of nanographene particles, but also give full play to the role of copper catalyst, giving the composite catalyst high catalytic activity and good antibacterial properties.

[0041] Furthermore, the average particle size of the graphene flakes is 100 to 500 nm, and the average particle size of the nanoparticles supported on the surface of the graphene flakes and generated by the copper foil flakes is less than 50 nm.

[0042] Preferably, the average particle size of the nanoparticles supported on the surface of the flaky graphene and generated from the flaky copper foil is less than 20 nm.

[0043] More preferably, the average particle size of the nanoparticles supported on the surface of the flaky graphene and generated from the flaky copper foil is less than 10 nm.

[0044] Furthermore, the sheet-like copper foil is a copper foil with a porous structure.

[0045] When the sheet-like copper foil is a porous sheet-like copper foil, at least part of the nano-graphene particles are deposited inside the porous structure of the sheet-like copper foil.

[0046] Of course, in actual operation, it is inevitable that some nano-graphene particles are deposited on the outer surface of the sheet-like copper foil.

[0047] The sheet copper foil with a porous structure can provide favorable conditions for the deposition and adhesion of nanographene particles, so that the nanographene particles can be stably attached to the surface of the sheet copper foil.

[0048] Furthermore, the sheet copper foil is a metal copper foil with a low-index crystal plane preferred orientation.

[0049] Specifically, the sheet copper foil is a metal copper foil with a (110) or (100) crystal plane preferred orientation.

[0050] Among the various crystal planes of copper, the atomic arrangement of the (110) and (100) crystal planes is relatively open and the surface atomic density is low, so the surface energy and surface tension are the largest. When compounded with flake graphite, due to their high surface energy and strong interaction force with flake graphite, the nanoparticles produced by the thermal decomposition of flake copper foil can be more easily spread evenly and tightly adhered to the surface of flake graphite, forming a stable composite structure.

[0051] Furthermore, the preparation method of the nitrogen-hybridized graphene catalyst loaded with nano-copper particles includes:

[0052] S1, copper foil pretreatment: After cleaning the copper foil, the flame formed by the combustion of combustible gas is sprayed onto the surface of the copper foil for segmented ablation. After the ablation is completed, the copper foil is cleaned again to obtain the ablated copper foil; then a discontinuous graphene layer is deposited on the surface of the copper foil using chemical vapor deposition, and then the copper foil is cut into 0.5 cm 2 The sheet-shaped copper foil is obtained as follows and set aside;

[0053] S2, preparation of graphene: weigh the raw materials according to the raw material component ratio: 30-50 parts by weight of graphite powder, 0.3-1 part by weight of sodium nitrate, 1.3-2.5 parts by weight of potassium permanganate, 3-6 parts by weight of concentrated sulfuric acid, 6-8 parts by weight of nitrite, 4-10 parts by weight of hydrogen peroxide, and 15-35 parts of water; then mix the concentrated sulfuric acid, graphite powder, sodium nitrate and water in an ice bath, then add potassium permanganate, and react under stirring for 1-2 hours, then heat the resulting mixture to 95-105° C. in an oil bath and continue to react for 0.6-1 hour; after the reaction is completed, add hydrogen peroxide, stir evenly, add the formulated amount of nitrite, and react at a pressure of 3-6 MPa and a temperature of 150-180° C. for 5-10 hours to obtain a flake graphene dispersion for later use;

[0054] S3, preparation of the catalyst: the flaky graphene dispersion prepared in the above step S2, 20 to 40 parts by weight of the nitrogen precursor, and 3 to 5 parts by weight of the pretreated flaky copper foil obtained in the above step S1 are mixed at room temperature, stirred evenly, and dried, and then placed in a closed reactor. First, the reaction is carried out at normal pressure and 450 to 550° C. for 2 to 2.5 hours, and then the pressure is increased to 0.5 to 3 MPa and maintained at this pressure for 1 to 5 minutes. The pressure relief valve is then quickly opened to instantly reduce the pressure in the reactor to normal pressure. The above pressure increase and pressure reduction process is then repeated 5 to 10 times. The reactor is then heated to 650 to 750° C. and the reaction is continued for 1 to 2 hours, so that the copper foil forms nano-scale fragment particles through migration, diffusion, decomposition, etc. under high temperature and high pressure, and can be loaded on the surface of the flaky graphene under the combined action of temperature, pressure and nitrogen-hybridized atoms to obtain the nitrogen-hybridized graphene catalyst loaded with nano-copper particles.

[0055] As some examples of the present invention, in step S1, the copper foil may be cleaned with solvents such as pure water, acetone, and anhydrous ethanol to make its surface clean and free of residue.

[0056] Preferably, in step S1, the thickness of the copper foil before pretreatment is ≤0.5 mm.

[0057] More preferably, in step S1, the thickness of the copper foil before pretreatment is 5-20 μm.

[0058] Preferably, in step S1, the copper foil surface is ablated using a 2-4 segmented ablation process. During the ablation process, the ablation temperature gradually increases with the increase in the number of ablation segments, and the ablation time for different ablation segments is basically the same, about 2-5 minutes.

[0059] Specifically, during the first ablation treatment, the flame temperature is 400-500°C; during the second ablation treatment, the flame temperature is 550-650°C; during the third ablation treatment, the flame temperature is 650-700°C; during the fourth ablation treatment, the flame temperature is 700-800°C, and the interval between each ablation treatment is 1-3 minutes.

[0060] As some examples of the present invention, in step S1, the combustible gas is selected from one or more of hydrogen, methane, liquefied petroleum gas, natural gas, biogas, coal gas, alcohol, etc.

[0061] Furthermore, during the ablation treatment, the copper foil can be fixed on the upper side of a porous support, and then the flame formed by the combustion of the combustible gas is sprayed to the lower side of the porous support for ablation treatment, wherein the porous support can be made of glass, ceramic, steel wire and other materials.

[0062] It should be noted that if the copper foil area is too large and the flame cannot fully cover the copper foil surface during the ablation process, the flame or copper foil can be moved back and forth so that the flame can be evenly sprayed on all parts of the copper foil surface. Generally, the area of ​​the copper foil can be controlled to be 5 to 10 times the area covered by the flame.

[0063] Furthermore, during the above copper foil ablation treatment, an appropriate amount of ablation aid may be added to promote the ablation process. As some examples of the present invention, the ablation aid is selected from one or more of iron oxide, cerium oxide, cobalt oxide, and lanthanum oxide. The amount of the ablation aid added is 0.1 to 0.3 g / m2 based on the surface area of ​​the copper foil. 2 The ablation aid is added in a manner of being evenly distributed on the surface of the copper foil close to the porous support.

[0064] Furthermore, during the above copper foil ablation treatment, if the copper foil is oxidized, the copper foil can be placed in a reducing atmosphere, such as a hydrogen atmosphere, and subjected to a reduction treatment at 700-800° C. for 0.5-1 hour.

[0065] During the above-mentioned copper foil ablation treatment, the high-temperature flame causes intense diffusion of gas molecules and atoms, as well as oxidation-reduction reactions, on the surface of the copper foil. For example, chemical reactions occur between gas molecules that penetrate into the lattice inside the metal, generating volatile gases such as CO2 and water. As these volatile gases gather, expand, and overflow inside the metal, nanoscale pores can be formed on the metal surface, ultimately resulting in a copper foil with a porous structure. The pores within the copper foil separate the metal phase into many tiny units, changing the surface properties of the copper foil, making it easier to adhere to the surface of the flaky graphene, and also making it easier to decompose the copper foil into smaller particle size fragments during subsequent processing.

[0066] Furthermore, the chemical vapor deposition process in step S1 is as follows:

[0067] First, a reducing gas is introduced into a reactor filled with inert gas and heated to 550-700° C., and then a carbon source gas and a reducing gas are pulsed and alternately introduced at 550-700° C.; wherein, the carbon source gas is introduced for 0.1-0.3 s, the residence time is 5-30 s, and the purge time is 10-20 s; the reducing gas is introduced for 0.1-0.3 s, the residence time is 10-20 s, the purge time is 10-20 s, and the pulse alternation cycle number is 300-800 times.

[0068] As some examples of the present invention, in the chemical vapor deposition process described in step S1, the carbon source gas is selected from one or more of methane, ethylene, acetylene, ethane, propane, ethanol, butanol, etc.

[0069] As some examples of the present invention, in the chemical vapor deposition process described in step S1, the reducing gas is hydrogen.

[0070] As some examples of the present invention, in the chemical vapor deposition process described in step S1, the inert gas is argon.

[0071] Furthermore, the pulse alternation cycle is specifically as follows:

[0072] First, a carbon source gas is introduced into the reactor and controlled to enter and be absorbed into the pores within the copper foil. After the carbon source gas is absorbed, an inert gas is introduced into the reactor to purge and remove excess carbon source gas. Then, a reducing gas is introduced into the reactor and controlled to enter and be absorbed into the pores within the copper foil. After the reaction between the reducing gas and the carbon source gas is complete, an inert gas is introduced into the reactor again to purge and remove excess reducing gas. In this way, during this pulse-alternating cycle, the silicon carbide particles formed will preferentially form in the pores within the copper foil and grow linearly.

[0073] In practical applications, for the chemical vapor deposition process, the number of pulse alternation cycles can be controlled according to the state of graphene particle formation, specifically, the linear graphene particles formed by graphene deposition can basically fill the pores in the copper foil and basically remain flush with the copper foil surface or slightly protrude from the copper foil surface. In this way, the copper foil surface after pretreatment will form Figure 1 and 2The structure shown is as follows: a porous structure 2 is formed on a sheet of copper foil 1, and nanographene particles 3 are deposited and filled within the porous structure 2. The resulting surface of the sheet of copper foil 1 is composed of a metal surface formed by the copper element in the base metal phase and a graphene surface formed after the nanographene particles 3 are filled. The nanographene particles 3 are embedded in the porous structure 2 of the sheet of copper foil 1, forming a stable and reliable bond between the two. While ensuring that the copper element is well exposed and fully exerts its catalytic properties, the nanographene particles 3 can also modify the surface of the sheet of copper foil 1, resulting in a low surface tension on the pre-treated sheet of copper foil 1, making it easy to combine with large particles of flake graphene to form a stable composite catalyst material. In addition, the surface of the treated sheet of copper foil 1 has tiny protrusions formed by the nanographene particles 3, which can prevent the particles of the sheet of copper foil 1 from agglomerating and improve dispersion performance.

[0074] Preferably, in step S2, concentrated sulfuric acid, graphite powder, sodium nitrate and water are mixed uniformly in an ice bath at 0-5°C.

[0075] As a preferred example of the present invention, in step S3, after mixing the flake graphene dispersion, the nitrogen precursor and the pretreated flake copper foil, 1 to 3 parts by weight of a dispersant can be added to the mixture, and after being evenly dispersed by ultrasound, the mixture is freeze-dried and the obtained solid is placed in a closed reactor for treatment.

[0076] As some examples of the present invention, the dispersant is selected from one or more of polyvinyl pyrrolidone, sodium dodecylbenzene sulfonate, polystyrene sulfonic acid, B6090 dispersant, AKN-2075 dispersant, and the like.

[0077] Freeze-drying can significantly improve the stability and dispersibility of solids, prevent the precipitation of liquid substances and violent movement between molecules, and thus reduce the agglomeration of nanoparticles.

[0078] As a preferred example of the present invention, in step S3, the nitrogen precursor is 7,7,8,8-tetracyanoquinodimethane.

[0079] In step S3, by adding a nitrogen precursor, graphene can be modified by using nitrogen atoms, and nitrogen atoms can be introduced into the graphene sheet structure. Then, the anchoring and dispersion effects of the nitrogen atoms in the hybrid graphene structure are utilized to effectively enhance the metal / graphene interface affinity and improve the metal loading state.

[0080] In addition, during the multiple pressure increase and pressure reduction processes in step S3, the gas impact force generated by the sudden pressure drop in the reactor can be used to further crush and decompose the copper foil, promoting its decomposition and generating fragments with smaller particle sizes. At the same time, the pressure increase and pressure reduction process can also be used to generate a strong mechanical stirring effect to promote uniform mixing between the materials. In addition, during the pressure increase and pressure reduction process, the graphene and copper foil will be subjected to a certain impact force, which helps to break the agglomeration structure between the materials and make the fragments generated by the copper foil better dispersed on the graphene surface. More importantly, by repeating the pressure increase and pressure reduction process, the contact between the graphene and the copper foil can be made closer, increasing the interaction force between them. This physical close contact helps the copper foil better adhere to the graphene surface, thereby improving the composite effect and ultimately forming a nano-scale copper particle load on the surface of the flake graphene.

[0081] Preferably, in step S3, an inert gas preheated to 500-600° C., such as nitrogen, argon, etc., may be used to increase and decrease the pressure of the sealed reaction container.

[0082] The following specific examples illustrate the nitrogen-hybridized graphene catalyst loaded with nano-copper particles and the preparation method thereof according to the present invention:

[0083] Example 1

[0084] Preparation of nitrogen-hybridized graphene catalyst loaded with nano-copper particles:

[0085] S1, copper foil pretreatment: After cleaning the copper foil, a flame formed by burning combustible gas is sprayed onto the surface of the copper foil for segmented ablation treatment. The total number of ablation treatment segments is 3, wherein the flame temperature of the first ablation treatment segment is 400°C; the flame temperature of the second ablation treatment segment is 550°C; the flame temperature of the third ablation treatment segment is 650°C; and the flame temperature of the fourth ablation treatment segment is 700°C. The ablation treatment time of each segment is 5 minutes, and there is a 1-minute interval between each ablation treatment segment.

[0086] After the ablation is completed, the copper foil is cleaned again to obtain the ablated copper foil;

[0087] A discontinuous graphene layer was then deposited on the copper foil surface using chemical vapor deposition. The chemical vapor deposition process was as follows: first, a reducing gas was introduced into a reactor filled with inert gas and heated to 550°C. Then, a carbon source gas and a reducing gas were pulsed and alternately introduced at 550°C. The carbon source gas was introduced for 0.3 seconds, held for 20 seconds, and purged for 10 seconds. The reducing gas was introduced for 0.3 seconds, held for 20 seconds, and purged for 10 seconds. The pulses were alternately cycled 320 times.

[0088] Then cut the copper foil into 0.5cm 2 Next, the sheet-shaped copper foil is obtained and set aside;

[0089] S2, preparation of graphene: weigh the following raw materials according to the raw material component ratio: 30 parts by weight of graphite powder, 0.3 parts by weight of sodium nitrate, 1.3 parts by weight of potassium permanganate, 3 parts by weight of concentrated sulfuric acid, 6 parts by weight of nitrite, 4 parts by weight of hydrogen peroxide, and 15 parts of water; then, mix the concentrated sulfuric acid, graphite powder, sodium nitrate, and water in an ice bath, then add potassium permanganate, and react under stirring for 1 hour. Then, heat the resulting mixture to 100° C. in an oil bath and continue to react for 0.8 hour. After the reaction is complete, add hydrogen peroxide, stir evenly, add the formulated amount of nitrite, and react at a pressure of 5 MPa and a temperature of 160° C. for 8 hours to obtain a flake graphene dispersion for later use;

[0090] S3, preparation of the catalyst: the flaky graphene dispersion prepared in the above step S2, 20 parts by weight of the nitrogen precursor, and 3 parts by weight of the pretreated flaky copper foil obtained in the above step S1 are mixed at room temperature, stirred evenly, and dried, and then placed in a closed reactor. First, the reaction is carried out at normal pressure and 450°C for 2.5 hours, and then the pressure is increased to 2 MPa and maintained at this pressure for 3 minutes. The pressure relief valve is then quickly opened to instantly reduce the pressure in the reactor to normal pressure. The above pressure increase and pressure reduction process is then repeated 5 times. Then, the reactor is heated to 700°C and the reaction is continued for 1 hour to obtain the nitrogen-hybridized graphene catalyst loaded with nano-copper particles.

[0091] Example 2

[0092] Preparation of nitrogen-hybridized graphene catalyst loaded with nano-copper particles:

[0093] S1, copper foil pretreatment: After cleaning the copper foil, the flame formed by the combustion of combustible gas is sprayed onto the surface of the copper foil for segmented ablation treatment. The total number of ablation treatment segments is 2, among which the flame temperature of the first ablation treatment segment is 500°C; the flame temperature of the second ablation treatment segment is 650°C; the flame temperature of the third ablation treatment segment is 700°C; the flame temperature of the fourth ablation treatment segment is 800°C. The ablation treatment time of each segment is 3 minutes, and the interval between each ablation treatment segment is 3 minutes. During the ablation treatment, 0.2g / m2 of the surface area of ​​the copper foil is added. 2 The ablation aid iron oxide;

[0094] After the ablation is completed, the copper foil is cleaned again to obtain the ablated copper foil;

[0095] A discontinuous graphene layer was then deposited on the copper foil surface using chemical vapor deposition. The chemical vapor deposition process was as follows: a reducing gas was first introduced into a reactor filled with inert gas and heated to 600°C. A carbon source gas and a reducing gas were then pulsed in alternately at 600°C. The carbon source gas was introduced for 0.2 seconds, held for 5 seconds, and purged for 15 seconds. The reducing gas was introduced for 0.2 seconds, held for 10 seconds, and purged for 15 seconds, and the pulsed alternation cycle was repeated 570 times.

[0096] Then cut the copper foil into 0.5cm 2 Next, the sheet-shaped copper foil is obtained and set aside;

[0097] S2, preparation of graphene: weigh the following raw materials according to the raw material component ratio: 40 parts by weight of graphite powder, 0.5 parts by weight of sodium nitrate, 2 parts by weight of potassium permanganate, 4 parts by weight of concentrated sulfuric acid, 7 parts by weight of nitrite, 6 parts by weight of hydrogen peroxide, and 20 parts of water; then, mix the concentrated sulfuric acid, graphite powder, sodium nitrate, and water in an ice bath, then add potassium permanganate, and react under stirring for 1.5 hours. Then, heat the resulting mixture to 95° C. in an oil bath and continue to react for 1 hour; after the reaction is completed, add hydrogen peroxide, stir evenly, add the formulated amount of nitrite, and react at a pressure of 3 MPa and a temperature of 150° C. for 10 hours to obtain a flake graphene dispersion for later use;

[0098] S3, preparation of the catalyst: the flaky graphene dispersion prepared in the above step S2, 30 parts by weight of the nitrogen precursor, and 4 parts by weight of the pretreated flaky copper foil obtained in the above step S1 are mixed at room temperature, stirred evenly, and dried, and then placed in a closed reactor. First, the reaction is carried out at normal pressure and 500°C for 2.2 hours, and then the pressure is increased to 3 MPa and maintained at this pressure for 1 minute. The pressure relief valve is then quickly opened to instantly reduce the pressure in the reactor to normal pressure. The above pressure increase and pressure reduction process is then repeated 8 times. Then, the reactor is heated to 750°C and the reaction is continued for 1.5 hours to obtain the nitrogen-hybridized graphene catalyst loaded with nano-copper particles.

[0099] Example 3

[0100] Preparation of nitrogen-hybridized graphene catalyst loaded with nano-copper particles:

[0101] S1, copper foil pretreatment: After cleaning the copper foil, a flame formed by burning combustible gas is sprayed onto the surface of the copper foil for segmented ablation treatment. The total number of ablation treatment segments is 4, wherein the flame temperature of the first ablation treatment segment is 430°C; the flame temperature of the second ablation treatment segment is 590°C; the flame temperature of the third ablation treatment segment is 670°C; and the flame temperature of the fourth ablation treatment segment is 750°C. The ablation treatment time of each segment is 2 minutes, and there is a 2-minute interval between each ablation treatment segment.

[0102] After the ablation is completed, the copper foil is cleaned again to obtain the ablated copper foil;

[0103] A discontinuous graphene layer was then deposited on the copper foil surface using chemical vapor deposition. The chemical vapor deposition process was as follows: first, a reducing gas was introduced into a reactor filled with inert gas and heated to 700°C. Then, a carbon source gas and a reducing gas were pulsed and alternately introduced at 700°C. The carbon source gas was introduced for 0.1s, held for 30s, and purged for 20s. The reducing gas was introduced for 0.1s, held for 15s, and purged for 20s. The pulses were alternately cycled 800 times.

[0104] Then cut the copper foil into 0.5cm 2 Next, the sheet-shaped copper foil is obtained and set aside;

[0105] S2, preparation of graphene: weigh the following raw materials according to the raw material component ratio: 50 parts by weight of graphite powder, 1 part by weight of sodium nitrate, 1.5 parts by weight of potassium permanganate, 6 parts by weight of concentrated sulfuric acid, 8 parts by weight of nitrite, 10 parts by weight of hydrogen peroxide, and 35 parts of water; then, mix the concentrated sulfuric acid, graphite powder, sodium nitrate, and water in an ice bath, then add potassium permanganate, and react under stirring for 2 hours. Then, heat the resulting mixture to 105° C. in an oil bath and continue to react for 0.6 hours; after the reaction is completed, add hydrogen peroxide, stir evenly, add the formulated amount of nitrite, and react at a pressure of 6 MPa and a temperature of 180° C. for 5 hours to obtain a flake graphene dispersion for later use;

[0106] S3, preparation of the catalyst: the flaky graphene dispersion prepared in the above step S2, 40 parts by weight of the nitrogen precursor, 5 parts by weight of the pretreated flaky copper foil obtained in the above step S1, and 2 parts by weight of the dispersant are mixed at room temperature, stirred evenly, and freeze-dried, and then placed in a closed reactor. First, the reaction is carried out at normal pressure and 550°C for 2 hours, and then the pressure is increased to 0.5 MPa and maintained at this pressure for 5 minutes. The pressure relief valve is then quickly opened to instantly reduce the pressure in the reactor to normal pressure. The above pressure increase and pressure reduction process is then repeated 10 times. Then, the reactor is heated to 650°C and the reaction is continued for 2 hours to obtain the nitrogen-hybridized graphene catalyst loaded with nano-copper particles.

[0107] Comparative Example 1

[0108] Preparation of nitrogen-hybridized graphene catalyst loaded with nano-copper particles:

[0109] The only difference between this embodiment and the above-mentioned embodiment 1 is that in step S1, the copper foil is not subjected to segmented ablation treatment. Instead, the copper foil is cleaned and then nano-graphene particles are directly deposited on the surface of the copper foil by chemical vapor deposition.

[0110] Comparative Example 2

[0111] Preparation of nitrogen-hybridized graphene catalyst loaded with nano-copper particles:

[0112] The only difference between this embodiment and the above-mentioned embodiment 1 is that in step S1, after the copper foil is subjected to segmented ablation and cleaned, the chemical vapor deposition method is not used to deposit nano-graphene particles on the surface of the copper foil.

[0113] Comparative Example 3

[0114] Preparation of nitrogen-hybridized graphene catalyst loaded with nano-copper particles:

[0115] The only difference between this embodiment and the above-mentioned embodiment 1 is that in step S3 , no nitrogen precursor is added, and the rest of the process is the same.

[0116] Comparative Example 4

[0117] Preparation of nitrogen-hybridized graphene catalyst loaded with nano-copper particles:

[0118] The only difference between this embodiment and the above-mentioned embodiment 1 is that in step S3, the multiple pressure increase and pressure reduction treatments in embodiment 1 are not performed. After reacting at 450° C. for 2.5 hours, the reactor is directly heated to 700° C. and the reaction is continued for 1 hour to obtain a nitrogen-hybridized graphene catalyst loaded with nano-copper particles.

[0119] Comparative Example 5

[0120] Preparation of nitrogen-hybridized graphene catalyst loaded with nano-copper particles:

[0121] The only difference between this embodiment and the above-mentioned embodiment 1 is that in step S1, a metal copper foil with a (111) crystal plane preferential orientation is selected as the raw material.

[0122] Comparative Example 6

[0123] Preparation of graphene catalyst:

[0124] A graphene flake dispersion was prepared according to step S2 in Example 1, and then the flake graphene dispersion was dried to obtain a graphene catalyst.

[0125] Comparative Example 7

[0126] Preparation of modified copper catalyst:

[0127] A pretreated copper foil was prepared according to step S1 in Example 1, and the pretreated copper foil was used as a modified copper catalyst.

[0128] Test Example 1

[0129] The microscopic morphology of the nitrogen-hybridized graphene catalyst loaded with nano-copper particles prepared in the above-mentioned embodiments 1 to 3 was observed using a transmission electron microscope, and it was found that in the catalyst prepared by the present invention, the graphene material had a two-dimensional lamellar structure, and the fragments produced by the decomposition of the flaky copper foil were evenly distributed on the surface of the flaky graphene.

[0130] Figure 3 This is a representative transmission electron microscope photograph of the catalyst prepared by the invention. The test sample is the catalyst prepared in Example 1 above, in which the particle size of the flaky graphene is about 200-500 nm, and the particle size of the fragments produced by the decomposition of the flaky copper foil is about 1-10 nm, achieving the goal of loading nano-copper particles on the surface of the flaky graphene.

[0131] Test Example 2

[0132] The elemental composition of the nitrogen-hybridized graphene catalyst loaded with nano-copper particles prepared in the above-mentioned embodiments 1 to 3 was analyzed using an X-ray photoelectron spectrometer. Figure 4 This is a representative X-ray photoelectron spectroscopy analysis diagram of the catalyst prepared by the invention. The test sample is the catalyst prepared in Example 1 above. The results further confirm the loading of copper element on the graphene surface.

[0133] Test Example 3

[0134] The catalyst materials prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were subjected to electrocatalytic activity tests to electrocatalytically degrade acetaminophen and tetracycline hydrochloride. The tests were conducted using a constant potential current meter.

[0135] The test process is as follows: add 200 mL of 10 mg L -1 Acetaminophen solution or tetracycline hydrochloride was added, and 0.2g NaCl was added as electrolyte. The prepared catalyst material was fixed on a 2.5cm 2 The carbon cloth is used as the anode and the cathode is 2.0 cm 2The electrocatalytic process was performed using a magnetic stirrer for continuous stirring. 1 mL of water sample was collected at specified time intervals and placed in a 2 mL centrifuge tube. 1 mL of methanol was added to quench free radicals. The sample was filtered through a 0.22 μm organic filter membrane. The acetaminophen and tetracycline hydrochloride contents were determined using a 2998 PDA (246 nm) high-performance liquid chromatography (Waters-2695). The residual ratio was expressed as C / C0, where C0 is the initial concentration of the solution and C is the concentration of the solution at time t.

[0136] The electrocatalytic activity of the catalyst materials prepared in Examples 1 to 3 and Comparative Examples 1 to 7 was tested according to the above test process, and the following results were obtained:

[0137] (1) The degradation effects of the catalysts obtained in Example 1 and Comparative Example 6 on acetaminophen at different times were compared to obtain Figure 5 The effect of the catalyst material on the degradation of acetaminophen is shown;

[0138] (2) The degradation effect of the catalyst obtained in Example 1 on tetracycline hydrochloride at different times was analyzed to obtain Figure 6 The effect of the catalyst material shown is on the degradation of tetracycline hydrochloride;

[0139] (3) The degradation efficiency (degradation time 50 min) of the catalyst materials prepared in Examples 1 to 3 and Comparative Examples 1 to 7 was compared in the above test process to obtain the results shown in Table 1 below:

[0140] Table 1 Degradation efficiency of acetaminophen by catalyst materials

[0141]

[0142]

[0143] (4) The degradation efficiency (degradation time 50 min) of the catalyst materials prepared in Examples 1 to 3 and Comparative Examples 1 to 7 for tetracycline hydrochloride in the above test process was compared to obtain the results shown in Table 2 below:

[0144] Table 2 Degradation efficiency of catalyst materials for tetracycline hydrochloride

[0145]

[0146]

[0147] The embodiments of the present application are described above in conjunction with the accompanying drawings. Unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are within the protection of this application.

Claims

1. A nitrogen-hybridized graphene catalyst loaded with nano-copper particles, characterized in that: The catalyst is formed by compounding flaky graphene and flaky copper foil under the anchoring effect of nitrogen atoms. Nanographene particles are deposited on the flaky copper foil, and the nanoparticles generated by the flaky copper foil are uniformly loaded on the surface of the flaky graphene.

2. The nitrogen-hybridized graphene catalyst loaded with nano-copper particles according to claim 1, characterized in that: The nano-graphene particles form a discontinuous graphene layer on the surface of the flaky copper foil.

3. The nitrogen-hybridized graphene catalyst loaded with nano-copper particles according to claim 2, characterized in that: The coverage rate of the surface of the sheet-like copper foil covered by the nano-graphene particles is ≤30%.

4. The nitrogen-hybridized graphene catalyst loaded with nano-copper particles according to claim 1 or 3, characterized in that: The average particle size of the flake graphene is 100 to 500 nm, and the average particle size of the nanoparticles supported on the surface of the flake graphene and generated by the flake copper foil is less than 50 nm.

5. The nitrogen-hybridized graphene catalyst loaded with nano-copper particles according to claim 1, characterized in that: The sheet-like copper foil is a copper foil with a porous structure, and at least part of the nanographene particles are deposited inside the porous structure of the sheet-like copper foil.

6. The nitrogen-hybridized graphene catalyst loaded with nano-copper particles according to claim 1, characterized in that: The sheet copper foil is a metal copper foil with a (110) or (100) crystal plane preferred orientation.

7. A method for preparing a nitrogen-hybridized graphene catalyst loaded with nano-copper particles, characterized in that: The preparation method is used to prepare the nitrogen-hybridized graphene catalyst loaded with nano-copper particles according to any one of claims 1 to 6, and the preparation method comprises the steps of: S1, copper foil pretreatment: After cleaning the copper foil, the flame formed by the combustion of combustible gas is sprayed onto the surface of the copper foil for segmented ablation. After the ablation is completed, the copper foil is cleaned again to obtain the ablated copper foil; then a discontinuous graphene layer is deposited on the surface of the copper foil using chemical vapor deposition, and then the copper foil is cut into 0.5 cm 2 The sheet-shaped copper foil is obtained as follows and set aside; S2, preparation of graphene: weigh the raw materials according to the raw material component ratio: 30-50 parts by weight of graphite powder, 0.3-1 part by weight of sodium nitrate, 1.3-2.5 parts by weight of potassium permanganate, 3-6 parts by weight of concentrated sulfuric acid, 6-8 parts by weight of nitrite, 4-10 parts by weight of hydrogen peroxide, and 15-35 parts of water; then mix the concentrated sulfuric acid, graphite powder, sodium nitrate and water in an ice bath, then add potassium permanganate, and react under stirring for 1-2 hours, then heat the resulting mixture to 95-105° C. in an oil bath and continue to react for 0.6-1 hour; after the reaction is completed, add hydrogen peroxide, stir evenly, add the formulated amount of nitrite, and react at a pressure of 3-6 MPa and a temperature of 150-180° C. for 5-10 hours to obtain a flake graphene dispersion for later use; S3, preparation of the catalyst: the flaky graphene dispersion prepared in the above step S2, 20 to 40 parts by weight of the nitrogen precursor, and 3 to 5 parts by weight of the pretreated flaky copper foil obtained in the above step S1 are mixed at room temperature, stirred evenly, and dried, and then placed in a closed reactor. First, the reaction is carried out at normal pressure and 450 to 550° C. for 2 to 2.5 hours, and then the pressure is increased to 0.5 to 3 MPa and maintained at this pressure for 1 to 5 minutes. The pressure relief valve is then quickly opened to instantly reduce the pressure in the reactor to normal pressure. The above pressure increase and pressure reduction process is then repeated 5 to 10 times. Then, the reactor is heated to 650 to 750° C. and the reaction is continued for 1 to 2 hours to obtain the nitrogen-hybridized graphene catalyst loaded with nano-copper particles.

8. The method for preparing the nitrogen-hybridized graphene catalyst loaded with nano-copper particles according to claim 7, characterized in that: In step S1, the copper foil surface is ablated using a 2-4 segmented ablation process. During the ablation process, the ablation temperature gradually increases with the increase in the number of ablation segments, and the ablation time for each segment is 2-5 minutes.

9. The method for preparing the nitrogen-hybridized graphene catalyst loaded with nano-copper particles according to claim 8, characterized in that: During the first ablation treatment, the flame temperature is 400-500°C; during the second ablation treatment, the flame temperature is 550-650°C; during the third ablation treatment, the flame temperature is 650-700°C; during the fourth ablation treatment, the flame temperature is 700-800°C, and the interval between each ablation treatment is 1-3 minutes.

10. The method for preparing the nitrogen-hybridized graphene catalyst loaded with nano-copper particles according to claim 7, characterized in that: The chemical vapor deposition process in step S1 is as follows: First, a reducing gas is introduced into a reactor filled with inert gas and heated to 550-700° C., and then a carbon source gas and a reducing gas are pulsed and alternately introduced at 550-700° C.; wherein, the carbon source gas is introduced for 0.1-0.3 s, the residence time is 5-30 s, and the purge time is 10-20 s; the reducing gas is introduced for 0.1-0.3 s, the residence time is 10-20 s, the purge time is 10-20 s, and the pulse alternation cycle number is 300-800 times.

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