A method for preparing carbon-supported single-atom material by microwave-assisted heating

Abstract

The present invention provides the use of a promoter in the preparation of carbon-supported single-atom materials by microwave heating; the promoter includes one or more of lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate. The present invention uses a specific promoter for the preparation of carbon-supported single-atom materials by microwave heating, and further adds a microwave absorber zinc chloride to fully pyrolyze an organic precursor with poor microwave absorption capacity under microwaves to obtain a highly carbonized carbon-supported metal single-atom material. The present invention uses zinc chloride as a microwave absorber to absorb microwave energy for heating, and the promoter is used to enhance the wave absorption capacity of zinc chloride, greatly increase the microwave heating temperature, and achieve full pyrolysis of the organic precursor, and the addition of the promoter not only greatly enhances its microwave heating capacity, but also has the advantages of low cost and easy removal after heating.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon-supported single-atom material preparation, and relates to the application of a promoter in the preparation of carbon-supported single-atom materials by microwave heating and a method for preparing carbon-supported single-atom materials, and in particular to a method for preparing carbon-supported single-atom materials by microwave-assisted heating. Background Art

[0002] Carbon-supported single-atom materials have attracted great attention in the fields of catalysis, optoelectronics, etc. due to their excellent conductivity, ultra-high stability and abundant anchoring sites. However, the traditional pyrolysis method used to construct carbon-supported single-atom materials is not only time-consuming, but also requires a long time of heating, resulting in high energy and time waste. Microwave heating has low energy consumption and short time consumption, which can effectively solve the problems of traditional heating.

[0003] However, the microwave-assisted heating reported so far mainly focuses on carbon materials because they can effectively absorb microwave energy. However, most organic precursors have poor microwave absorption capacity, which greatly limits the further application of microwave-assisted heating in the preparation of carbon-supported single-atom materials.

[0004] Therefore, how to find a more suitable way to further broaden the raw materials for preparing carbon-supported single-atom materials by microwave-assisted heating, solve the above-mentioned problems existing in the prior art, and construct carbon-supported single-atom materials from the direction of organic precursors is still in great need of exploration and is also one of the focuses of widespread attention of many forward-looking researchers in the industry. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide an application of a promoter in the preparation of carbon-supported single-atom materials by microwave heating and a preparation method of carbon-supported single-atom materials, in particular, a preparation method of carbon-supported single-atom materials by microwave-assisted heating. The preparation method provided by the present invention enhances the microwave absorption capacity of the raw material, greatly increases the microwave heating temperature, and achieves sufficient pyrolysis of the organic precursor, so that the carbon-supported single-atom material can be prepared using the organic precursor as a carbon source. Moreover, the preparation method has simple synthesis steps and mild conditions, is suitable for large-scale production promotion and application, and has good practical prospects.

[0006] The present invention provides the use of a promoter in preparing carbon-supported single-atom materials by microwave heating;

[0007] The promoter includes one or more of lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate.

[0008] Preferably, the application is specifically the application of the promoter and zinc chloride in the preparation of carbon-supported single-atom materials by microwave heating;

[0009] The mass ratio of zinc chloride to accelerator is 1:(0.2-1.2);

[0010] The raw materials for the microwave heating method include organic precursors.

[0011] Preferably, the organic precursor includes an organic precursor containing a metal element;

[0012] The organic precursor includes one or more of MOFs, COFs, metal-organic complexes, metal-organic coordination polymers, and ionic polymers;

[0013] The zinc chloride is a microwave absorber;

[0014] The raw materials for the microwave heating method also include a nitrogen source and / or a carbon source.

[0015] The present invention provides a method for preparing a carbon-supported single-atom material, comprising the following steps:

[0016] 1) An organic precursor, zinc chloride and a promoter are mixed, subjected to microwave heating, and then washed to obtain a carbon-supported single-atom material.

[0017] Preferably, the organic precursor includes an organic precursor containing a metal element;

[0018] The promoter includes one or more of lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate;

[0019] The mass ratio of the organic precursor to zinc chloride is 1:(1.5-8);

[0020] The carbon-supported metal single atom material is a highly carbonized carbon-supported metal single atom material.

[0021] Preferably, the organic precursor includes one or more of MOFs, COFs, metal-organic complexes, metal-organic coordination polymers, and ionic polymers;

[0022] The mass ratio of the organic precursor to the accelerator is 1:(0.2-8);

[0023] The mass ratio of the zinc chloride to the accelerator is 1:(0.2-1.2).

[0024] Preferably, the organic precursor includes one or more of Ni-ZIF, Ni-MET-6, metal phthalocyanine, metal porphyrin, iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate and copper acetylacetonate;

[0025] The microwave heating is carried out in an air atmosphere;

[0026] The zinc chloride is a microwave absorber;

[0027] In the carbon-supported metal single atom material, the metal single atom is connected to the carbon through an -N- bond.

[0028] Preferably, the raw materials for the microwave heating method further include a nitrogen source and / or a carbon source;

[0029] The nitrogen source includes one or more of melamine, dicyandiamide, urea, ammonium fluoride, ammonium chloride, ammonium bromide and ammonium bicarbonate;

[0030] The carbon source includes one or more of ascorbic acid, sucrose, cyclodextrin, glucose, carotene, starch and polyvinyl pyrrolidone;

[0031] The mass ratio of the organic precursor to the nitrogen source is 1:(2-10);

[0032] The mass ratio of the organic precursor to the carbon source is 1:(2-30).

[0033] Preferably, the heating power of the microwave is 400-3000W;

[0034] The microwave has a waveband of 300 to 6000 MHz;

[0035] The microwave heating time is 1.5 to 10 minutes;

[0036] The microwave heating further comprises a grinding step and / or a washing step.

[0037] Preferably, the ultrasonic washing solution is one or more of water, hydrochloric acid solution, nitric acid solution and sulfuric acid solution;

[0038] The pH value of the ultrasonic washing solution is 1 to 7;

[0039] The ultrasonic washing time is 0.5 to 5 minutes;

[0040] The ultrasonic washing is performed 1 to 5 times.

[0041] The present invention provides the use of a promoter in preparing a carbon-supported single-atom material by a microwave heating method; the promoter includes one or more of lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate. Compared with the prior art, the present invention uses a specific promoter for preparing a carbon-supported single-atom material by a microwave heating method, and further adds a microwave absorber zinc chloride to fully pyrolyze an organic precursor with poor microwave absorption capacity under microwaves to obtain a highly carbonized carbon-supported metal single-atom material.

[0042] The method for obtaining a carbon-supported metal single-atom material by adding zinc chloride and a promoter to assist microwave heating provided by the present invention, zinc chloride is used as a microwave absorber to absorb microwave energy for heating, and an auxiliary agent is used to enhance the wave absorption capacity of zinc chloride, greatly improve the microwave heating temperature, and achieve full pyrolysis of the organic precursor, and by adding a promoter to zinc chloride, its microwave heating capacity is greatly enhanced, and the problem that the graphitization degree of the carbon substrate after the carbonization of the precursor is low when only zinc chloride is added, the conductivity is poor, and the wave absorption capacity of a single zinc chloride is weak is solved. Moreover, the combination of zinc chloride and a promoter has the advantages of low cost and easy removal after heating compared to traditional carbon materials as microwave absorbers. At the same time, the preparation method has simple synthesis steps, mild conditions, is suitable for large-scale production promotion and application, and has good practical prospects.

[0043] The experimental results show that when the promoter is not added, the microwave pyrolysis is not sufficient and the carbonization degree of the obtained material is very low. However, after adding the promoter, the material can be fully pyrolyzed to obtain a carbon-supported single-atom material with a high degree of graphitization. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Schematic diagram of the synthesis route of precursor Ni-ZIF-8;

[0045] Figure 2 The X-ray diffraction pattern of the powder of Ni-ZIF-8 synthesized in Example 1 of the present invention;

[0046] Figure 3 Schematic diagram of the synthesis route of Ni1-NC-50 carbon-supported single-atom catalyst;

[0047] Figure 4 The powder X-ray diffraction patterns of Ni1-NC-50, Ni1-NC-15 and Ni1-NC-0 synthesized in Example 1 of the present invention;

[0048] Figure 5 The Raman spectra of Ni1-NC-50, Ni1-NC-15 and Ni1-NC-0 synthesized in Example 1 of the present invention;

[0049] Figure 6 N2 adsorption diagram of Ni1-NC-50 and Ni1-NC-15 synthesized in Example 1 of the present invention;

[0050] Figure 7 The pore size distribution diagram of Ni1-NC-50 and Ni1-NC-15 synthesized in Example 1 of the present invention;

[0051] Figure 8 This is the Fourier transform extended X-ray absorption fine structure of Ni1-NC-50 and Ni1-NC-15 synthesized in Example 1 of the present invention. DETAILED DESCRIPTION

[0052] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention.

[0053] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0054] The raw materials used in the present invention have no particular limitation on their purity. The present invention preferably uses analytical purity or conventional purity in the field of preparation of carbon-supported metal single atom materials.

[0055] The brands and abbreviations of all raw materials of the present invention are conventional brands and abbreviations in the art. Each brand and abbreviation is clear and definite in the field of its related use. Those skilled in the art can purchase them from the market or prepare them by conventional methods according to the brands, abbreviations and corresponding uses.

[0056] The abbreviations of all processes of the present invention are conventional abbreviations in the field, and each abbreviation is clear and unambiguous in the field of its related use. Those skilled in the art can understand its conventional process steps based on the abbreviations.

[0057] The present invention provides the use of a promoter in preparing carbon-supported single-atom materials by microwave heating;

[0058] The promoter includes one or more of lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate.

[0059] In the present invention, the promoter includes one or more of lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate, and can be lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate or cesium carbonate.

[0060] In the present invention, the application is preferably the application of the promoter and zinc chloride in the preparation of carbon-supported single-atom materials by microwave heating.

[0061] In the present invention, the mass ratio of zinc chloride to accelerator is preferably 1:(0.2-1.2), more preferably 1:(0.4-1.0), and more preferably 1:(0.6-0.8).

[0062] In the present invention, the raw materials of the microwave heating method preferably include organic precursors, more preferably organic precursors containing metal elements, more preferably one or more of MOFs, COFs, metal-organic complexes, metal-organic coordination polymers, and ionic polymers, more preferably MOFs, COFs, metal-organic complexes, metal-organic coordination polymers or ionic polymers.

[0063] In the present invention, the zinc chloride is preferably a microwave absorber.

[0064] In the present invention, the raw materials for the microwave heating method preferably further include a nitrogen source and / or a carbon source.

[0065] The present invention provides a method for preparing a carbon-supported single-atom material, comprising the following steps:

[0066] 1) An organic precursor, zinc chloride and a promoter are mixed, subjected to microwave heating, and then washed to obtain a carbon-supported single-atom material.

[0067] In the present invention, the promoter preferably includes one or more of lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate, and more preferably lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate or cesium carbonate.

[0068] In the present invention, the mass ratio of the organic precursor to zinc chloride is preferably 1:(1.5-8), more preferably 1:(3-7), and more preferably 1:(4-6).

[0069] In the present invention, the carbon-supported metal single atom material is preferably a highly carbonized carbon-supported metal single atom material.

[0070] In the present invention, the organic precursor preferably includes an organic precursor containing a metal element, more preferably one or more of MOFs, COFs, metal organic complexes, metal-organic coordination polymers, and ionic polymers, more preferably MOFs, COFs, metal organic complexes, metal-organic coordination polymers or ionic polymers. Specifically, the organic precursor preferably includes one or more of Ni-ZIF, Ni-MET-6, metal phthalocyanine, metal porphyrin, iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, and copper acetylacetonate, more preferably Ni-ZIF-8, Ni-MET-6 (Ni-Zn-(C2N3H2)2), metal phthalocyanine, metal porphyrin, iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, or copper acetylacetonate. Wherein, when the organic precursor is one or more of metal phthalocyanine, metal porphyrin, iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, and copper acetylacetonate, the raw material preferably also includes a nitrogen source and / or a carbon source.

[0071] In the present invention, the nitrogen source preferably includes one or more of melamine, dicyandiamine, urea, ammonium fluoride, ammonium chloride, ammonium bromide and ammonium bicarbonate, more preferably melamine, dicyandiamine, urea, ammonium fluoride, ammonium chloride, ammonium bromide or ammonium bicarbonate.

[0072] In the present invention, the carbon source preferably includes one or more of ascorbic acid, sucrose, cyclodextrin, glucose, carotene, starch and polyvinyl pyrrolidone, more preferably ascorbic acid, sucrose, cyclodextrin, glucose, carotene, starch or polyvinyl pyrrolidone.

[0073] In the present invention, the mass ratio of the organic precursor to the nitrogen source is preferably 1:(2-10), more preferably 1:(3-9), more preferably 1:(4-8), and more preferably 1:(4-7).

[0074] In the present invention, the mass ratio of the organic precursor to the carbon source is preferably 1:(2-30), more preferably 1:(5-25), and even more preferably 1:(10-20).

[0075] In the present invention, the mass ratio of the organic precursor to the accelerator is preferably 1:(0.2-8), more preferably 1:(1-6), and more preferably 1:(3-4).

[0076] In the present invention, the mass ratio of zinc chloride to accelerator is preferably 1:(0.2-1.2), more preferably 1:(0.4-1.0), and more preferably 1:(0.6-0.8).

[0077] In the present invention, the microwave heating is preferably performed under an air atmosphere.

[0078] In the present invention, the zinc chloride is preferably a microwave absorber.

[0079] In the present invention, the metal single atom in the carbon-supported metal single atom material is preferably connected to the carbon via an -N- bond.

[0080] In the present invention, the heating power of the microwave is preferably 400-3000W, more preferably 600-2000W, and even more preferably 800-1600W.

[0081] In the present invention, the wavelength of the microwave is preferably 300 to 6000 MHz, more preferably 400 to 1000 MHz.

[0082] In the present invention, the microwave heating time is preferably 1.5 to 10 minutes, more preferably 2 to 8 minutes, and more preferably 3 to 5 minutes.

[0083] In the present invention, the microwave heating preferably further comprises a grinding step and / or a washing step, more preferably a grinding step or a washing step.

[0084] In the present invention, the ultrasonic cleaning solution is preferably one or more of water, hydrochloric acid solution, nitric acid solution and sulfuric acid solution, more preferably water, hydrochloric acid solution, nitric acid solution or sulfuric acid solution.

[0085] In the present invention, the pH value of the ultrasonic washing solution is preferably 1-7, more preferably 2-4.

[0086] In the present invention, the ultrasonic washing time is preferably 0.5 to 5 minutes, more preferably 1 to 4 minutes, and more preferably 2 to 3 minutes.

[0087] In the present invention, the number of ultrasonic washing is preferably 1 to 5 times, more preferably 2 to 4 times.

[0088] The present invention is to complete and refine the overall technical solution, better ensure the structure and composition of the carbon-supported single-atom material, further improve the wave absorption ability of the organic precursor and the stability and efficiency of the preparation process. The preparation method of the carbon-supported single-atom material specifically includes the following steps:

[0089] By adding microwave absorber zinc chloride and promoter, the organic precursor with poor microwave absorption capacity can be fully pyrolyzed under microwaves to obtain highly carbonized carbon-supported metal single atom materials.

[0090] Specifically, the promoter is lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate or cesium carbonate.

[0091] Specifically, the specific steps of the method for preparing carbon-supported single-atom materials by microwave-assisted heating are as follows:

[0092] The organic precursor is physically mixed with zinc chloride and a promoter, placed in an open container, and then subjected to microwave heating. The obtained solid is taken out and ground, and then ultrasonically washed in a solution to remove the remaining zinc and promoter. Finally, the solid is centrifuged and dried to obtain a carbon-supported nanomaterial.

[0093] Specifically, the mass ratio of the organic precursor to zinc chloride is 1:(1.5-8).

[0094] Specifically, the mass ratio of the organic precursor to the accelerator is 1:(0.2-8).

[0095] Specifically, the mass ratio of the zinc chloride to the accelerator is 1:(0.2-1.2).

[0096] Specifically, the microwave heating power is 400-3000W.

[0097] Specifically, the microwave heating time is 1.5 to 10 minutes.

[0098] Specifically, the ultrasonic washing solution is water, hydrochloric acid solution, nitric acid solution, sulfuric acid solution, or a combination of any two of them.

[0099] Specifically, the pH value of the ultrasonic washing solution is 1-7.

[0100] Specifically, the ultrasonic washing time is 0.5 to 5 minutes.

[0101] Specifically, the ultrasonic washing is performed 1 to 5 times.

[0102] Furthermore, the present invention is achieved through the following technical solutions:

[0103] The organic precursor is physically mixed with zinc chloride and a promoter, placed in an open container, and then subjected to microwave heating. The obtained solid is taken out and ground, and then ultrasonically washed in a solution to remove the remaining zinc and promoter. Finally, the solid is centrifuged and dried to obtain a carbon-supported single-atom material.

[0104] Specifically, the promoter is lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate or cesium carbonate; the best is potassium chloride.

[0105] Specifically, the mass ratio of the organic precursor to zinc chloride is 1:1.5-8; the optimal mass ratio is 1:2.

[0106] Specifically, the mass ratio of the organic precursor to the accelerator is 1:0.2-8; the optimal mass ratio is 1:0.5.

[0107] Specifically, the mass ratio of the zinc chloride to the accelerator is 1:0.2-1.2; the optimal mass ratio is 1:0.5.

[0108] Specifically, the microwave heating power is 400-3000W; the optimal heating power is 800W.

[0109] Specifically, the microwave heating time is 1.5-10 minutes; the optimal microwave heating time is 3 minutes.

[0110] Specifically, the ultrasonic washing solution is water, hydrochloric acid solution, nitric acid solution, sulfuric acid solution, or a combination of any two of them.

[0111] Specifically, the pH value of the ultrasonic washing solution is 1-7; the optimal pH value is 1.

[0112] Specifically, the ultrasonic washing time is 0.5-5 minutes; the optimal time value is 1 minute.

[0113] Specifically, the number of ultrasonic washing is 1-5 times; the optimal number is 2 times.

[0114] The above content of the present invention provides the use of a promoter in preparing a carbon-supported single-atom material by microwave heating and a method for preparing a carbon-supported single-atom material by microwave-assisted heating. The present invention uses a specific promoter for preparing a carbon-supported single-atom material by microwave heating, and further adds a microwave absorber, zinc chloride, to fully pyrolyze an organic precursor with poor microwave absorption under microwaves to obtain a highly carbonized carbon-supported metal single-atom material.

[0115] The method for obtaining a carbon-supported metal single-atom material by adding zinc chloride and a promoter to assist microwave heating provided by the present invention, zinc chloride is used as a microwave absorber to absorb microwave energy for heating, and an auxiliary agent is used to enhance the wave absorption capacity of zinc chloride, greatly improve the microwave heating temperature, and achieve full pyrolysis of the organic precursor, and by adding a promoter to zinc chloride, its microwave heating capacity is greatly enhanced, and the problem that the graphitization degree of the carbon substrate after the carbonization of the precursor is low when only zinc chloride is added, the conductivity is poor, and the wave absorption capacity of a single zinc chloride is weak is solved. Moreover, the combination of zinc chloride and a promoter has the advantages of low cost and easy removal after heating compared to traditional carbon materials as microwave absorbers. At the same time, the preparation method has simple synthesis steps, mild conditions, is suitable for large-scale production promotion and application, and has good practical prospects.

[0116] The experimental results show that when the promoter is not added, the microwave pyrolysis is not sufficient and the carbonization degree of the obtained material is very low. However, after adding the promoter, the material can be fully pyrolyzed to obtain a carbon-supported single-atom material with a high degree of graphitization.

[0117] In order to further illustrate the present invention, the application of the promoter provided by the present invention in the preparation of carbon-supported single-atom materials by microwave heating and a method for preparing carbon-supported single-atom materials are described in detail in combination with the examples below. However, it should be understood that these examples are implemented on the premise of the technical scheme of the present invention, and detailed implementation methods and specific operating processes are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following examples.

[0118] Example 1

[0119] Synthesis of carbon-supported single atoms using Ni-ZIF-8 as a precursor by microwave-assisted heating

[0120] (1) Synthesis of precursor Ni-ZIF-8:

[0121] See also Figure 1 , Figure 1 Schematic diagram of the synthesis route of the precursor Ni-ZIF-8.

[0122] Nickel nitrate hexahydrate (1.6 g) and zinc nitrate hexahydrate (0.8 g) were added to 60 mL of methanol (solution A). 2-Methylimidazole (3.76 g) was dissolved in 60 mL of methanol (solution B). Solution B was then added to solution A, and the mixture was stirred at room temperature for 12 hours. It was washed three times with ethanol, centrifuged and dried at 60°C for 12 hours to obtain Ni-ZIF-8.

[0123] The obtained Ni-ZIF-8 was subjected to XRD spectrum test, and the results are shown in Figure 2 middle.

[0124] See also Figure 2 , Figure 2 This is the powder X-ray diffraction pattern of Ni-ZIF-8 synthesized in Example 1 of the present invention.

[0125] By comparing the theoretical XRD spectrum of the powder and the XRD spectrum of the Ni-ZIF-8 synthesized by the present invention, it can be determined that the intended Ni-ZIF-8 is successfully synthesized by the method of the present invention.

[0126] (2) Synthesis of Ni1-NC-50 carbon-supported single-atom catalyst:

[0127] See also Figure 3 , Figure 3Schematic diagram of the synthesis route of Ni1-NC-50 carbon-supported single-atom catalyst.

[0128] 120mg Ni-ZIF-8 and zinc chloride (240mg) and potassium chloride (60mg) are ground by using an agate mortar, and then the mixture is put into a microwave tube, and then it is placed in a conical flask to keep it vertical. They are further placed in a household microwave oven, and microwave heating for 3 minutes is carried out at a power of 800W. The mixture obtained after heating is ultrasonically washed in 1M hydrochloric acid for 1 minute and centrifuged, and then repeated washing 1 time is performed to remove residual zinc chloride and potassium chloride. Finally it is dried at 90 ℃ for 12 hours, and finally Ni1-NC-50 is obtained.

[0129] (3) Synthesis of comparative sample Ni1-NC-15 single atom catalyst:

[0130] 120mg Ni-ZIF-8 and zinc chloride (240mg) and potassium chloride (18mg) are ground by using an agate mortar, and then the mixture is put into a microwave tube, and then placed in a conical flask to keep it vertical. They are further placed in a household microwave oven, and microwave heating for 3 minutes is carried out at a power of 800W. The mixture obtained after heating is ultrasonically washed in 1M hydrochloric acid for 1 minute and centrifuged, and then washed repeatedly 1 time, and residual zinc chloride and potassium chloride are removed. Finally, it is dried at 90 ℃ for 12 hours, and finally Ni1-NC-15 is obtained.

[0131] (4) Synthesis of single atom catalyst without promoter Ni1-NC-0 comparison sample:

[0132] 120mg Ni-ZIF-8 and zinc chloride (240mg) are ground by using an agate mortar, and then the mixture is put into a microwave tube, then it is placed in a conical flask and it is kept vertical. They are further placed in a domestic microwave oven, and carry out 3 minutes of microwave heating at a power of 800W. The mixture obtained after heating is ultrasonically washed in 1M hydrochloric acid for 1 minute and centrifuged, and then repeated washing 1 time is removed residual zinc chloride and potassium chloride. Finally it is dried at 90 ℃ for 12 hours, finally obtain Ni1-NC-0.

[0133] The obtained Ni1-NC-50, Ni1-NC-15 and Ni1-NC-0 were tested by XRD spectra, and the results are shown in Figure 4 middle.

[0134] See also Figure 4 , Figure 4 Powder X-ray diffraction patterns of Ni1-NC-50, Ni1-NC-15 and Ni1-NC-0 synthesized in Example 1 of the present invention.

[0135] like Figure 4 As shown in the figure, the intensities of C(002) and C(101) peaks in the XRD patterns of Ni1-NC-0, Ni1-NC-15 and Ni1-NC-50 gradually increase, which means that with the increase of the promoter, the carbonization degree of the material increases and the carbonization temperature increases. At the same time, no metal peaks are found in the XRD results.

[0136] The obtained Ni1-NC-50, Ni1-NC-15 and Ni1-NC-0 were tested by Raman spectroscopy, and the results are shown in Figure 3 middle.

[0137] See also Figure 5 , Figure 5 This is the Raman spectra of Ni1-NC-50, Ni1-NC-15 and Ni1-NC-0 synthesized in Example 1 of the present invention.

[0138] like Figure 5 As shown in the figure, Ni1-NC-0 has no obvious D peak and G peak, indicating that the carbonization degree of the material obtained by microwave decomposition without adding a promoter is very low. However, Ni1-NC-50 and Ni1-NC-15 have obvious D peak and G peak, indicating that the addition of the promoter significantly increases the carbonization degree of the material.

[0139] The obtained Ni1-NC-50 and Ni1-NC-15 were subjected to nitrogen adsorption test, and the results are shown in Figure 6 and Figure 7 middle.

[0140] See also Figure 6 , Figure 6 This is the N2 adsorption diagram of Ni1-NC-50 and Ni1-NC-15 synthesized in Example 1 of the present invention.

[0141] See also Figure 7 , Figure 7 This is the pore size distribution diagram of Ni1-NC-50 and Ni1-NC-15 synthesized in Example 1 of the present invention.

[0142] like Figure 6 and 7 As shown, Ni1-NC-50 and Ni1-NC-15 have large specific surface area and mesoporous structure, indicating that this synthesis method is helpful to obtain large specific surface area and mesoporous structure.

[0143] See also Figure 8 , Figure 8 This is the Fourier transform extended X-ray absorption fine structure of Ni1-NC-50 and Ni1-NC-15 synthesized in Example 1 of the present invention.

[0144] like Figure 8 As shown, in Ni1-NC-50 and Ni1-NC-15, Ni is coordinated with N, and there is no metallic Ni-Ni bond, indicating that the obtained Ni1-NC-50 and Ni1-NC-15 are single-atom catalysts.

[0145] Example 2

[0146] Microwave synthesis of carbon-supported single-atom materials using Ni-MET-6 as precursor

[0147] 0.4 g of zinc chloride and 0.075 g of nickel nitrate hexahydrate were dissolved in a solvent mixture consisting of 20 mL of DMF, 20 mL of ethanol, 30 mL of deionized water, and 10 mL of ammonium hydroxide to form solution A. A total of 0.625 mL of 1H-1,2,3-triazole was added dropwise to solution A, after which a white product was immediately formed. The suspension was stirred for 2 h. The obtained white precipitate was then collected by centrifugation after washing 3 times with DMF and ethanol. Finally, the wet powder was dried at 100 ° C for 24 hours to obtain the Ni-MET-6 precursor.

[0148] 120mg Ni-MET-6 precursor was ground with zinc chloride (240mg) and potassium chloride (60mg) using an agate mortar, and then the mixture was placed in a microwave tube, which was then placed in a conical flask to keep it vertical. They were further placed in a household microwave oven and microwave heated for 3 minutes at a power of 800W. The mixture obtained after heating was ultrasonically washed in 1M hydrochloric acid for 1 minute and centrifuged, and then washed again 1 time to remove residual zinc chloride and potassium chloride. Finally, it was dried at 90°C for 12 hours to finally obtain nickel single atoms.

[0149] Example 3

[0150] Microwave synthesis of carbon-supported single atoms using nickel phthalocyanine as precursor

[0151] 10 mg of nickel phthalocyanine, 100 mg of melamine and 125 mg of ascorbic acid were ground and mixed evenly, and then 240 mg of zinc chloride and 60 mg of potassium chloride were added and ground evenly using an agate mortar, and then the mixture was placed in a microwave tube, and then placed in a conical flask to keep it vertical. They were further placed in a household microwave oven and microwave heated at a power of 800 W for 3 minutes. The mixture obtained after heating was ultrasonically washed in 1M hydrochloric acid for 1 minute and centrifuged, and then washed again to remove residual zinc chloride and potassium chloride. Finally, it was dried at 90 ° C for 12 hours to finally obtain nickel single atoms.

[0152] The above is a detailed introduction to a method for preparing a carbon-supported single-atom material by microwave-assisted heating provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in the field to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing a carbon-supported single-atom material, characterized in that: The following steps are involved: The organic precursor, zinc chloride and accelerator are mixed, subjected to microwave heating, and then washed to obtain a carbon-supported single-atom material; The organic precursor includes one or more of Ni-ZIF, Ni-MET-6, metal phthalocyanine, metal porphyrin, iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate and copper acetylacetonate; The promoter includes one or more of lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and cesium carbonate; The microwave heating is performed under air atmosphere.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the organic precursor to zinc chloride is 1:(1.5-8); The carbon-supported metal single atom material is a highly carbonized carbon-supported metal single atom material.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the organic precursor to the accelerator is 1:(0.2~8).

4. The preparation method according to claim 1, characterized in that: The mass ratio of zinc chloride to accelerator is 1: (0.2-1.2); In the carbon-supported metal single atom material, the metal single atom is connected to the carbon through an -N- bond.

5. The preparation method according to claim 1, characterized in that: The raw materials for the microwave heating method also include a nitrogen source and / or a carbon source.

6. The preparation method according to claim 5, characterized in that: The nitrogen source includes one or more of melamine, dicyandiamide, urea, ammonium fluoride, ammonium chloride, ammonium bromide and ammonium bicarbonate; The carbon source includes one or more of ascorbic acid, sucrose, cyclodextrin, glucose, carotene, starch and polyvinyl pyrrolidone.

7. The preparation method according to claim 5, characterized in that: The mass ratio of the organic precursor to the nitrogen source is 1:(2-10); The mass ratio of the organic precursor to the carbon source is 1:(2-30).

8. The preparation method according to claim 1, characterized in that: The heating power of the microwave is 400-3000W; The microwave has a waveband of 300-6000 MHz; The microwave heating time is 1.5 to 10 minutes.

9. The preparation method according to claim 1, characterized in that: The microwave heating further comprises a grinding step and / or a washing step.

10. The preparation method according to claim 9, characterized in that: The solution for ultrasonic cleaning is one or more of water, hydrochloric acid solution, nitric acid solution and sulfuric acid solution; The pH value of the solution for ultrasonic washing is 1-7; The ultrasonic washing time is 0.5~5 minutes; The number of ultrasonic washings is 1 to 5 times.

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