Preparation method of carbon quantum dot loaded transition metal monatomic material and application thereof

Abstract

The application relates to the technical field of carbon quantum material, in particular to a preparation method and application of carbon quantum dot loaded transition metal monatomic material. The preparation method of the carbon quantum dot loaded transition metal monatomic material is as follows: carbon quantum dot raw materials are mixed with a solvent to obtain a carbon quantum dot precursor solution, a transition metal-ligand precursor solution is prepared in sequence, the carbon quantum dot precursor solution and the transition metal-ligand precursor solution are uniformly mixed, and then are treated by a solvothermal method, and the carbon quantum dot loaded transition metal monatomic material is prepared by filtration. The carbon quantum dot loaded transition metal monatomic material provided by the application has good fluorescence performance, and can realize ton-level production. The production process is simple, the production equipment is easy to operate, the production cost is low, the production is green, environment-friendly and pollution-free, and can promote crop root growth, enhance nitrogen fertilizer absorption, improve crop quality, shorten the maturation period and strengthen the nutritional components in the agricultural field.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of carbon quantum materials, in particular to a preparation method of a carbon quantum dot loaded transition metal monatomic material and application thereof. BACKGROUND

[0002] Small molecule organic carbon plays an important role in promoting agricultural development and increasing the economic benefits of farmers. The strong efficacy of small molecule organic carbon: 1. effectively supplementing carbon elements: by applying organic carbon fertilizer, carbon is supplemented to microbial fertilizer to improve its effective ratio, functional microorganisms rapidly develop into dominant populations in the soil, and the biodiversity generated by the benign circulation of the soil ecology further promotes the improvement of biological fertility as the soil water, gas and thermal environment improves; 2. improving the soil and increasing the soil fertility: it can rapidly mobilize and expand the role of functional microorganisms to rapidly improve the soil. However, the existing small molecule organic carbon material has low utilization rate and has problems of easy residue of drug damage, pollution of the environment and the like. In order to solve the above technical problems, the application provides a preparation method of a carbon quantum dot loaded transition metal monatomic material. SUMMARY

[0003] In order to solve the problems of easy residue of drug damage, pollution of the environment and the like of the micro-carbon material in the prior art. The application provides a preparation method of a carbon quantum dot loaded transition metal monatomic material and application thereof in the field of agriculture.

[0004] The preparation method of the carbon quantum dot loaded transition metal monatomic material provided by the application is realized through the following technical scheme:

[0005] The carbon quantum dot loaded transition metal monatomic material is composed of carbon quantum dot raw materials, transition metals and transition metal-ligands; the carbon quantum dot raw materials are any one or a combination of multiple of citric acid, ascorbic acid, ethylenediaminetetraacetic acid disodium, glucose, sucrose, proline, valine, urea, glycine, glutamic acid, phenylalanine, cysteine and thiourea; the transition metal is any one of potassium, calcium, manganese, iron, cobalt, nickel, copper and zinc; the transition metal-ligand is any one or a combination of multiple of o-phenanthroline, melamine, ethylenediaminetetraacetic acid disodium and dimethylimidazole;

[0006] The preparation method of the carbon quantum dot loaded transition metal monatomic material is as follows:

[0007] Step one, mixing the carbon quantum dot raw materials and a solvent to obtain a carbon quantum dot precursor solution;

[0008] Meanwhile, a transition metal-ligand precursor solution is prepared;

[0009] Step two, after mixing the carbon quantum dot precursor solution and the transition metal-ligand precursor solution uniformly, the transition metal-ligand precursor solution is treated by a solvothermal method, the transition metal-ligand and the transition metal form a single-atom active site, and the carbon quantum dot loaded transition metal single-atom material is obtained by filtration.

[0010] Preferably, in step one, the carbon quantum dot raw material is mixed with a solvent to prepare a carbon quantum dot precursor solution with a concentration of 10-60wt%, and the solution is stirred and dissolved or dispersed uniformly at room temperature, the stirring speed is controlled at 100-800rpm, and the stirring time is 2-24h, to obtain the carbon quantum dot precursor solution; the solvent is deionized water.

[0011] Preferably, in step one, the transition metal precursor solution is prepared by dissolving a transition metal salt in deionized water, the transition metal salt is at least one of a chloride salt, a nitrate salt, and a sulfate salt, the solution is stirred and dissolved at room temperature, the stirring speed is controlled at 100-800rpm / min, and the stirring time is 2-12h, to obtain a transition metal precursor solution with a concentration of 1-10wt%.

[0012] Preferably, in step two, the prepared transition metal precursor solution is mixed with the transition metal-ligand to form a stable transition metal-ligand mixed solution, the molar ratio of the metal in the transition metal salt contained in the transition metal precursor solution to the transition metal-ligand is 1:(1-8), and the mixture is stirred sufficiently at a temperature of 30-80℃ for 2-6h.

[0013] Preferably, in step two, after mixing the carbon quantum dot precursor solution and the transition metal-ligand precursor solution uniformly, the transition metal-ligand precursor solution is treated by a solvothermal method, the transition metal-ligand and the transition metal form a single-atom active site, and the carbon quantum dot loaded transition metal single-atom material is obtained by filtration.

[0014] Preferably, in step two, after the solvothermal reaction is completed, the carbon quantum dot loaded transition metal single-atom material is obtained by precise filtration using a food-grade nylon ultra-fine filter screen.

[0015] Preferably, in step two, after the solvothermal reaction is completed, the carbon quantum dot loaded transition metal single-atom material is obtained by precise filtration once using a 3000-mesh food-grade nylon ultra-fine filter screen and then by precise filtration twice using a 4000-mesh food-grade nylon ultra-fine filter screen.

[0016] Preferably, the carbon quantum dot raw material is any one or a combination of multiple of citric acid, ascorbic acid, glucose, sucrose, proline, and valine.

[0017] Preferably, the carbon quantum dot loaded transition metal single-atom material is applied in the field of agriculture.

[0018] The carbon quantum dot loaded transition metal single atom material of the present application adopts single atom technology, has high metal utilization rate, saves materials, has lower cost, and has a synergistic effect of carbon quantum dots combined with metal. The main effects include promoting root growth, enhancing nitrogen fertilizer absorption, improving crop quality, shortening the maturation period, and strengthening nutritional components. The carbon quantum dot loaded transition metal single atom material can be applied to various crops such as rice, wheat, corn, and soybean, and shows good effects. The carbon quantum dot can be used as a foliar spray and soil irrigation.

[0019] In summary, the present application has the following advantages:

[0020] 1. The carbon quantum dot loaded transition metal single atom material of the present application adopts single atom technology, has high metal utilization rate, saves materials, has lower cost, and has a synergistic effect of carbon quantum dots combined with metal.

[0021] 2. The carbon quantum dot loaded transition metal single atom material of the present application has simple production process equipment and is easy to operate, making it easier to realize commercial ton-level production.

[0022] 3. The carbon quantum dot loaded transition metal single atom material of the present application has the main effects of promoting root growth, enhancing nitrogen fertilizer absorption, improving crop quality, shortening the maturation period, and strengthening nutritional components. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Ton-level production of carbon quantum dot loaded transition metal single atom material.

[0024] Figure 2 Carbon quantum dot loaded transition metal single atom material (in order from left to right: carbon quantum dot loaded potassium metal single atom material, carbon quantum dot loaded calcium metal single atom material, carbon quantum dot loaded manganese metal single atom material, carbon quantum dot loaded iron metal single atom material, carbon quantum dot loaded cobalt metal single atom material, carbon quantum dot loaded nickel metal single atom material, carbon quantum dot loaded copper metal single atom material, carbon quantum dot loaded zinc metal single atom material, sulfur-doped carbon quantum dots), fluorescence effect.

[0025] Figure 3 A preparation method of a carbon quantum dot loaded transition metal single atom material and its application in the field of agriculture, onion rooting experiment.

[0026] Figure 4 A preparation method of a carbon quantum dot loaded transition metal single atom material and its application in the field of agriculture, crop growth experiment. DETAILED DESCRIPTION

[0027] In order to further understand the present application, the creativity of the present application is further described below in combination with examples and comparative examples.

[0028] Raw materials

[0029] Raw materials Source CAS No. Citric acid Merck 77-92-9 Ascorbic acid Merck 50-81-7 Disodium ethylenediaminetetraacetate Merck 6381-92-6 Glucose Merck 50-99-7 Sucrose Merck 57-50-1 Proline Merck 147-85-3 Valine Merck 72-18-4 Urea Merck 57-13-6 Glycine Merck 56-40-6 Glutamic acid Merck 56-86-0 Phenylalanine Merck 63-91-2 Cysteine Merck 52-90-4 Thiourea Merck 62-56-6 O-phenanthroline Merck 3829-86-5 Melamine Merck 108-78-1 2-methylimidazole Merck 693-98-1 Potassium chloride Merck 7447-40-7 Calcium chloride dihydrate Merck 233-140-8 Manganese chloride tetrahydrate Merck 13446-34-9 Iron nitrate nonahydrate Merck 15244-10-7 Cobalt chloride hexahydrate Merck 7791-13-1 Nickel chloride hexahydrate Merck 7791-20-0 Copper sulfate pentahydrate Merck 7758-99-8 Zinc chloride Merck 7646-85-7 Embodiments

[0030] In the present application, carbon quantum dots are combined with unique single-atom technology to prepare single-atom materials loaded with transition metals, which can be used as a new type of carbon fertilizer for agricultural production. This super environmentally friendly carbon quantum dot new carbon nanomaterial is a carbon quantum dot loaded with transition metal single-atom material in the present application. This material is non-toxic and has good biocompatibility, and can achieve a synergistic effect. In practice, single-atom materials loaded with transition metals can be applied to various crops, such as rice, wheat, corn, soybeans, and other crops, and have shown good results, and can be used as foliar spraying, soil perfusion, and other usage methods.

[0031] During use, the concentration and frequency should be reasonably selected according to different crop types, different growth stage conditions, crop growth conditions, environmental conditions (temperature, humidity, light, etc.), and fertilizer requirements of crops, to achieve the best use effect, make the release speed in the soil more suitable, and continuously provide nutrients for plants, so that crops can better absorb nutrients and improve nitrogen fixation efficiency, thereby accelerating growth and improving crop quality.

[0032] In addition, the carbon quantum dot loaded with transition metal single-atom material also has the effect of improving soil structure, enhancing soil aeration and drainage, which is of great significance for preventing soil salinization and hardening. Carbon quantum dots have brought revolutionary changes to agriculture and made great contributions to our food safety and environmental protection.

[0033] The carbon quantum dot raw material is any one or a combination of more than one of citric acid, ascorbic acid, disodium ethylenediaminetetraacetate, glucose, sucrose, proline, valine, urea, glycine, glutamic acid, phenylalanine, cysteine, and thiourea. Preferably, the carbon quantum dot raw material is any one or a combination of more than one of citric acid, ascorbic acid, glucose, sucrose, proline, and valine.

[0034] The main components of the carbon quantum dot material are C, H, and O, and the carbon content is relatively high.

[0035] The main components of the nitrogen-doped carbon quantum dot material are C, H, O, and N, and the carbon content and nitrogen content are relatively high.

[0036] The main components of the sulfur-doped carbon quantum dot material are C, H, O, and S, and the carbon content and sulfur content are relatively high.

[0037] Both the nitrogen-doped carbon quantum dot material and the sulfur-doped carbon quantum dot material can further supplement nitrogen and sulfur elements, increase the synergistic effect between different elements, and reduce the use of nitrogen fertilizer.

[0038] Specifically, the preparation method of the carbon quantum dots in Example 1 is as follows:

[0039] Step one: 40wt% carbon quantum dot precursor solution was prepared. Carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose were weighed and prepared according to the ratio of 1:1:1:1. Deionized water was added, and the solution was stirred and dissolved or dispersed uniformly at room temperature. The stirring speed was controlled at 800 rpm, and the stirring time was 24 h. The carbon quantum dot precursor solution was obtained and ready for use.

[0040] Step two: the carbon quantum dot precursor solution in step one was then transferred to a reaction kettle and treated by solvothermal method under air atmosphere at 280℃. The heating rate was 5℃ / min, and the treatment time was 10 h. After natural cooling to room temperature, the carbon quantum dots were obtained by precise filtration using 3000 mesh food-grade nylon ultra-fine filter screen and 4000 mesh food-grade nylon ultra-fine filter screen in sequence.

[0041] The preparation method of the nitrogen-doped carbon quantum dots in Example 2 is as follows:

[0042] Step one: 50wt% nitrogen-doped carbon quantum dot precursor solution was prepared. Carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose and carbon quantum dot raw materials nitrogen-doped ligands urea, glycine, glutamic acid, phenylalanine were weighed and prepared according to the ratio of 1:1:1:1:1:1:1:1. Deionized water was added, and the solution was stirred and dissolved or dispersed uniformly at room temperature. The stirring speed was controlled at 700 rpm, and the stirring time was 18 h. The nitrogen-doped carbon quantum dot precursor solution was obtained and ready for use.

[0043] Step two: the nitrogen-doped carbon quantum dot precursor solution in step one was then transferred to a reaction kettle and treated by solvothermal method under air atmosphere at 280℃. The heating rate was 5℃ / min, and the treatment time was 12 h. After natural cooling to room temperature, the nitrogen-doped carbon quantum dots were obtained by precise filtration using 3000 mesh food-grade nylon ultra-fine filter screen and 4000 mesh food-grade nylon ultra-fine filter screen in sequence.

[0044] The preparation method of the sulfur-doped carbon quantum dots in Example 3 is as follows:

[0045] Step one: 60wt% sulfur-doped carbon quantum dot precursor solution was prepared. Carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose and carbon quantum dot raw materials sulfur-doped ligands cysteine, thiourea were weighed and prepared according to the ratio of 1:1:1:1:1:1. Deionized water was added, and the solution was stirred and dissolved or dispersed uniformly at room temperature. The stirring speed was controlled at 500 rpm, and the stirring time was 12 h. The nitrogen-doped carbon quantum dot precursor solution was obtained and ready for use.

[0046] Step two: then the nitrogen-doped carbon quantum dot precursor solution of step one is transferred to the reaction kettle and treated by solvothermal method at 280°C in air atmosphere, the heating rate is 10°C / min, the treatment time is 16h, then naturally cooled to room temperature, and then sequentially uses 3000 mesh food grade nylon ultra-fine filter screen, 4000 mesh food grade nylon ultra-fine filter screen to filter the sulfur-doped carbon quantum dots.

[0047] Specifically, a preparation method of a carbon quantum dot loaded transition metal single atom material, comprising the following steps:

[0048] Step one, preparation of carbon quantum dot precursor solution: carbon quantum dot raw materials are mixed with solvent-deionized water to prepare a carbon quantum dot precursor solution with a concentration of 10-60wt%, which is uniformly dissolved or dispersed at room temperature, the stirring speed is controlled at 100-800rpm, and the stirring time is 2-24h, to obtain the carbon quantum dot precursor solution;

[0049] Meanwhile, a transition metal precursor solution is prepared: a transition metal salt is dissolved in deionized water, the transition metal salt is at least one of chloride, nitrate and sulfate, and is dissolved at room temperature with a stirring speed of 100-800rpm / min and a stirring time of 2-12h to obtain a transition metal precursor solution with a concentration of 1-10wt%; preparation of transition metal-ligand precursor solution: the prepared transition metal precursor solution is mixed with transition metal-ligand, the molar ratio of the metal in the transition metal salt in the transition metal precursor solution to the transition metal-ligand is 1:(1-8), and the mixture is fully stirred at a temperature of 30-80°C for 2-6h to form a stable transition metal-ligand mixed solution;

[0050] Step two, the carbon quantum dot precursor solution and the transition metal-ligand precursor solution are uniformly mixed and then treated by solvothermal method at 280-300°C in air atmosphere, the heating rate is 1-10°C / min, the treatment time is 2-16h, then naturally cooled to room temperature, the transition metal-ligand forms a single atom active site with the transition metal, after the solvothermal reaction, a 3000 mesh food grade nylon ultra-fine filter screen is used for primary precision filtration, and then a 4000 mesh food grade nylon ultra-fine filter screen is used for secondary precision filtration to obtain the carbon quantum dot loaded transition metal single atom material, which is applied in the field of agriculture.

[0051] The carbon quantum dot loaded transition metal single atom material can supplement trace elements for crop diseases caused by lack of nutrients, improve the synergistic effect of the two, and will not cause environmental burden, and improve the quality of crops.

[0052] The carbon quantum dot loaded transition metal single atom material is composed of carbon quantum dot raw materials, transition metal, and transition metal-ligand.

[0053] The transition metal is any one of potassium, calcium, manganese, iron, cobalt, nickel, copper, and zinc.

[0054] The transition metal-ligand is any one or a combination of multiple of orthophenanthroline, melamine, ethylenediaminetetraacetic acid disodium, and dimethyl imidazole.

[0055] A preparation method of a carbon quantum dot loaded transition metal single atom material, comprising the following steps:

[0056] Example 4: (2% potassium)

[0057] Step one: prepare 60wt% carbon quantum dot precursor solution, weigh carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose, and prepare according to a ratio of 1:1:1:1, add deionized water, stir to dissolve and disperse uniformly at room temperature, control the stirring speed at 500 rpm / min, and stir for 10 h to obtain the carbon quantum dot precursor solution, which is ready for use;

[0058] Meanwhile, prepare 2wt% potassium chloride precursor solution, weigh potassium chloride and dissolve in deionized water, stir to dissolve at room temperature, control the stirring speed at 200 rpm / min, and stir for 2 h to obtain the transition metal precursor solution, which is ready for use;

[0059] Prepare the transition metal-ligand precursor solution, mix the ligand ethylenediaminetetraacetic acid disodium with the transition metal precursor solution prepared above, the molar ratio of potassium metal in the transition metal precursor solution to the ligand is 1:2, fully stir at 30°C for 2 h to form a stable transition metal-ligand mixed solution,

[0060] Step two: pour the transition metal-ligand mixed solution of step one into the 60wt% carbon quantum dot precursor solution of step one while stirring, mix uniformly again, and then transfer to a reaction kettle for treatment by solvothermal method at 280°C in air atmosphere, the heating rate is 10°C / min, the treatment time is 16 h, and then naturally cool to room temperature. After the solvothermal reaction is completed, use a 3000 mesh food-grade nylon ultra-fine filter screen for primary precision filtration, and then use a 4000 mesh food-grade nylon ultra-fine filter screen for secondary precision filtration to obtain the carbon quantum dot loaded transition metal single atom material.

[0061] Example 5 differs from example 4 in that: a preparation method of a carbon quantum dot loaded transition metal single atom material, comprising the following steps: (2% calcium)

[0062] Step one: prepare 50wt% carbon quantum dot precursor solution, weigh carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose, proline, and valine, prepare according to a ratio of 1:1:1:1:1:1, add deionized water, stir to dissolve and disperse uniformly at room temperature, control the stirring speed at 600 rpm / min, and stir for 6 h to obtain the carbon quantum dot precursor solution, which is ready for use;

[0063] Meanwhile, 2wt% calcium chloride precursor solution was prepared, calcium chloride dihydrate was weighed and dissolved in deionized water, stirring at room temperature, stirring speed was controlled at 300 rpm / min, stirring time was 3h, and transition metal precursor solution was obtained for standby;

[0064] The transition metal-ligand precursor solution was prepared, and the ligand-2, 2'-bipyridine was fully mixed with the above prepared transition metal precursor solution. The molar ratio of manganese metal in the transition metal precursor solution to the ligand was 1:4. The mixture was fully stirred at 40°C for 3h to form a stable transition metal-ligand mixed solution.

[0065] Step two: the transition metal-ligand mixed solution of step one was poured into the 50wt% carbon quantum dot precursor solution in step one while stirring, and then transferred to a reaction kettle for treatment by solvothermal method at 280°C in air atmosphere. The heating rate was 5°C / min, and the treatment time was 12h. After natural cooling to room temperature, the solvothermal reaction was completed. After one precision filtration with 3000 mesh food grade nylon ultra-fine filter screen and two precision filtrations with 4000 mesh food grade nylon ultra-fine filter screen, the carbon quantum dot loaded transition metal single atom material was obtained.

[0066] Example 6 is different from example 4 in that a method for preparing a carbon quantum dot loaded transition metal single atom material includes the following steps: (5% manganese)

[0067] Step one: 30wt% carbon quantum dot precursor solution was prepared. Carbon quantum dot raw materials such as citric acid, ascorbic acid, glucose, sucrose and proline were weighed and prepared according to the ratio of 1:1:1:1:1. Deionized water was added, and stirring and dissolving or dispersing were carried out at room temperature. The stirring speed was controlled at 600 rpm / min, and the stirring time was 16h to obtain the carbon quantum dot precursor solution for standby.

[0068] Meanwhile, 5wt% manganese chloride precursor solution was prepared. Manganese chloride tetrahydrate was weighed and dissolved in deionized water, stirring at room temperature, stirring speed was controlled at 400 rpm / min, stirring time was 5h, and transition metal precursor solution was obtained for standby;

[0069] The transition metal-ligand precursor solution was prepared, and the ligand-2, 2'-bipyridine was fully mixed with the above prepared transition metal precursor solution. The molar ratio of manganese metal in the transition metal precursor solution to the ligand was 1:4. The mixture was fully stirred at 40°C for 3h to form a stable transition metal-ligand mixed solution.

[0070] Step two: the transition metal-ligand mixed solution of step one is poured into the 30wt% carbon quantum dot precursor solution in step one while stirring, and then mixed uniformly again and transferred to a reaction kettle for treatment by solvothermal method at 280°C in an air atmosphere, the heating rate is 2°C / min, the treatment time is 6h, and then naturally cooled to room temperature. After the solvothermal reaction is completed, a 3000 mesh food-grade nylon ultra-fine filter screen is used for once precision filtration, and then a 4000 mesh food-grade nylon ultra-fine filter screen is used for twice precision filtration to obtain the carbon quantum dot loaded transition metal single atom material.

[0071] The difference between example 7 and example 4 is that a preparation method of a carbon quantum dot loaded transition metal single atom material includes the following steps: (6% iron)

[0072] Step one: prepare a 30wt% carbon quantum dot precursor solution. Citric acid, ascorbic acid, glucose, sucrose, and valine are weighed and prepared according to a ratio of 1:1:1:1:1. Deionized water is added, and the mixture is stirred and dissolved or dispersed uniformly at room temperature. The stirring speed is controlled at 500 rpm, and the stirring time is 8h. The carbon quantum dot precursor solution is obtained and ready for use.

[0073] Meanwhile, a 6wt% ferric nitrate precursor solution is prepared. Ferric nitrate nonahydrate is dissolved in deionized water, and the mixture is stirred and dissolved at room temperature. The stirring speed is controlled at 500 rpm / min, and the stirring time is 8h. The transition metal precursor solution is obtained and ready for use.

[0074] Prepare a transition metal-ligand precursor solution. The ligand-melamine is fully mixed with the above prepared transition metal precursor solution. The molar ratio of manganese metal in the transition metal precursor solution to the ligand is 1:5. The mixture is fully stirred at 50°C for 5h to form a stable transition metal-ligand mixed solution.

[0075] Step two: the transition metal-ligand mixed solution of step one is poured into the 30wt% carbon quantum dot precursor solution in step one while stirring, and then mixed uniformly again and transferred to a reaction kettle for treatment by solvothermal method at 280°C in an air atmosphere, the heating rate is 2°C / min, the treatment time is 6h, and then naturally cooled to room temperature. After the solvothermal reaction is completed, a 3000 mesh food-grade nylon ultra-fine filter screen is used for once precision filtration, and then a 4000 mesh food-grade nylon ultra-fine filter screen is used for twice precision filtration to obtain the carbon quantum dot loaded transition metal single atom material.

[0076] The difference between example 8 and example 4 is that a preparation method of a carbon quantum dot loaded transition metal single atom material includes the following steps: (6% cobalt)

[0077] Step one: prepare 40wt% carbon quantum dot precursor solution, take carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose, according to the ratio of 1:1:1:1, add deionized water, room temperature stirring, stirring speed control at 700rpm / min, stirring time for 8h, get carbon quantum dot precursor solution, standby;

[0078] At the same time, prepare 6wt% cobalt chloride precursor solution, take cobalt chloride hexahydrate dissolved in deionized water, room temperature stirring, stirring speed control at 600rpm / min, stirring time for 6h, get transition metal precursor solution, standby;

[0079] Prepare transition metal-ligand precursor solution, ligand-melamine and the above prepared transition metal precursor solution are fully mixed, the molar ratio of cobalt metal in transition metal precursor solution to ligand is 1:6, fully stir at 60℃ for 5h, form stable transition metal-ligand mixed solution,

[0080] Step two: pour the transition metal-ligand mixed solution of step one into the 30wt% carbon quantum dot precursor solution of step one while stirring, mix uniformly again, then transfer to the reaction kettle and treat by solvothermal method at 280℃ in air atmosphere, the heating rate is 2℃ / min, the treatment time is 8h, then naturally cool to room temperature, after the solvothermal reaction is completed, use 3000 mesh food grade nylon ultra-fine filter screen for once precision filtration, then use 4000 mesh food grade nylon ultra-fine filter screen for twice precision filtration to obtain carbon quantum dot loaded transition metal single atom material.

[0081] The difference between example 9 and example 4 is that the preparation method of carbon quantum dot loaded transition metal single atom material includes the following steps: (8% nickel)

[0082] Step one: prepare 40wt% carbon quantum dot precursor solution, take carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose, according to the ratio of 1:1:1:1, add deionized water, room temperature stirring, stirring speed control at 600rpm / min, stirring time for 5h, get carbon quantum dot precursor solution, standby;

[0083] At the same time, prepare 8wt% nickel chloride precursor solution, take nickel chloride hexahydrate dissolved in deionized water, room temperature stirring, stirring speed control at 700rpm / min, stirring time for 8h, get transition metal precursor solution, standby;

[0084] Prepare transition metal-ligand precursor solution, ligand-orthophenanthroline and the above prepared transition metal precursor solution are fully mixed, the molar ratio of nickel metal in transition metal precursor solution to ligand is 1:7, fully stir at 80℃ for 6h, form stable transition metal-ligand mixed solution,

[0085] Step two: the transition metal-ligand mixed solution of step one is poured into the 40wt% carbon quantum dot precursor solution in step one while stirring, and then transferred to a reaction kettle after being mixed uniformly again, and then treated by solvothermal method at 280°C in air atmosphere, the heating rate is 5°C / min, the treatment time is 8h, and then naturally cooled to room temperature. After the solvothermal reaction is completed, a 3000 mesh food-grade nylon ultra-fine filter screen is used for once precision filtration, and then a 4000 mesh food-grade nylon ultra-fine filter screen is used for twice precision filtration to obtain the carbon quantum dot loaded transition metal single atom material.

[0086] The difference between example 10 and example 4 is that a preparation method of a carbon quantum dot loaded transition metal single atom material includes the following steps: (10% copper)

[0087] Step one: prepare a 20wt% carbon quantum dot precursor solution, weigh the carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose, proline, valine, and prepare them according to a ratio of 1:1:1:1:1:1. Add deionized water, stir and dissolve or disperse uniformly at room temperature, control the stirring speed at 300 rpm / min, and stir for 6h to obtain the carbon quantum dot precursor solution for standby use.

[0088] Meanwhile, prepare a 10wt% copper sulfate precursor solution, weigh the copper sulfate pentahydrate and dissolve it in deionized water, stir and dissolve at room temperature, control the stirring speed at 800 rpm / min, and stir for 10h to obtain the transition metal precursor solution for standby use.

[0089] Prepare a transition metal-ligand precursor solution, mix the ligand disodium ethylenediaminetetraacetate with the above prepared transition metal precursor solution, the molar ratio of copper metal in the transition metal precursor solution to the ligand is 1:8, fully stir at 80°C for 6h to form a stable transition metal-ligand mixed solution,

[0090] Step two: the transition metal-ligand mixed solution of step one is poured into the 20wt% carbon quantum dot precursor solution in step one while stirring, and then transferred to a reaction kettle after being mixed uniformly again, and then treated by solvothermal method at 280°C in air atmosphere, the heating rate is 5°C / min, the treatment time is 5h, and then naturally cooled to room temperature. After the solvothermal reaction is completed, a 3000 mesh food-grade nylon ultra-fine filter screen is used for once precision filtration, and then a 4000 mesh food-grade nylon ultra-fine filter screen is used for twice precision filtration to obtain the carbon quantum dot loaded transition metal single atom material.

[0091] The difference between example 11 and example 4 is that a preparation method of a carbon quantum dot loaded transition metal single atom material includes the following steps: (10% zinc)

[0092] Step one: prepare 10wt% carbon quantum dot precursor solution, weigh carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose, proline, and prepare according to the ratio of 1:1:1:1:1, add deionized water, stir to dissolve or disperse uniformly at room temperature, control the stirring speed at 400rpm / min, and stir for 6h to obtain carbon quantum dot precursor solution for standby;

[0093] At the same time, prepare 10wt% zinc chloride precursor solution, weigh zinc chloride and dissolve in deionized water, stir to dissolve at room temperature, control the stirring speed at 800rpm / min, and stir for 12h to obtain transition metal precursor solution for standby;

[0094] Prepare transition metal-ligand precursor solution, mix ligand-dimethylimidazole with the above prepared transition metal precursor solution, the molar ratio of zinc metal in the transition metal precursor solution to the ligand is 1:6, and fully stir at 70℃ for 4h to form a stable transition metal-ligand mixed solution,

[0095] Step two: pour the transition metal-ligand mixed solution of step one into the 20wt% carbon quantum dot precursor solution of step one while stirring, mix uniformly again, and then transfer to a reaction kettle for treatment by solvothermal method at 280℃ in air atmosphere, the heating rate is 2℃ / min, and the treatment time is 10h, then naturally cool to room temperature, after the solvothermal reaction is completed, use 3000 mesh food grade nylon ultra-fine filter screen for primary precision filtration, and then use 4000 mesh food grade nylon ultra-fine filter screen for secondary precision filtration to obtain carbon quantum dot loaded transition metal monatomic material.

[0096] The fluorescence effect of the carbon quantum dot loaded transition metal monatomic material prepared in the example is shown in Figure 2 .

[0097] The order from left to right: carbon quantum dot loaded potassium metal monatomic material, carbon quantum dot loaded calcium metal monatomic material, carbon quantum dot loaded manganese metal monatomic material, carbon quantum dot loaded iron metal monatomic material, carbon quantum dot loaded cobalt metal monatomic material, carbon quantum dot loaded nickel metal monatomic material, carbon quantum dot loaded copper metal monatomic material, carbon quantum dot loaded zinc metal monatomic material, and sulfur-doped carbon quantum dots.

[0098] Crop test method 1: onion rooting experiment, the specific test method is as follows: water culture method. The experimental results are shown in Figure 3 , and the diluted 2000-5000 times of the carbon quantum dots of example 1 can effectively promote the rooting of onions.

[0099] Crop test method 2: growth experiment of Chinese cabbage, the specific test method is as follows: soil irrigation. The experimental results are shown in Figure 4The carbon quantum dots of Example 1 after being diluted 5000 times can effectively promote the growth of Chinese cabbage, and the growth is obviously compared with the blank group.

[0100] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application, and the person skilled in the art can make a modification of the present embodiments without creative contribution according to the need after reading the present specification, but as long as in the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A method for preparing carbon quantum dot-supported transition metal single-atom materials, characterized in that: Includes the following steps: Step 1: Prepare a 30wt% carbon quantum dot precursor solution. Weigh the carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose, and proline, and mix them in a ratio of 1:1:1:1:

1. Add deionized water, stir at room temperature to dissolve or disperse evenly, control the stirring speed at 600 rpm / min, and stir for 16 hours to obtain the carbon quantum dot precursor solution for later use. Meanwhile, a 5wt% manganese chloride precursor solution was prepared by weighing manganese chloride tetrahydrate and dissolving it in deionized water, stirring at room temperature, controlling the stirring speed at 400 rpm / min, and stirring for 5 hours to obtain the transition metal precursor solution for later use. A transition metal-ligand precursor solution was prepared by thoroughly mixing the ligand-phenanthroline with the prepared transition metal precursor solution. The molar ratio of manganese metal to ligand in the transition metal precursor solution was 1:

4. The mixture was stirred thoroughly at 40°C for 3 hours to form a stable transition metal-ligand mixed solution. Step 2: While stirring, pour the transition metal-ligand mixed solution from Step 1 into the 30wt% carbon quantum dot precursor solution from Step 1. After mixing thoroughly, transfer the mixture to a reaction vessel and process it using a solvothermal method at 280℃ in an air atmosphere with a heating rate of 2℃ / min for 6 hours. After natural cooling to room temperature, after the solvothermal reaction is complete, perform a first precision filtration using a 3000-mesh food-grade nylon ultrafine filter, followed by a second precision filtration using a 4000-mesh food-grade nylon ultrafine filter to obtain carbon quantum dot-loaded transition metal single-atom material. The carbon quantum dot-loaded transition metal single-atom material is a carbon quantum dot-loaded manganese metal single-atom material.

2. A method for preparing carbon quantum dot-supported transition metal single-atom materials, characterized in that: Includes the following steps: Step 1: Prepare a 30wt% carbon quantum dot precursor solution. Weigh the carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose, and valine, and mix them in a ratio of 1:1:1:1:

1. Add deionized water, stir at room temperature to dissolve or disperse evenly, control the stirring speed at 500 rpm, and stir for 8 hours to obtain the carbon quantum dot precursor solution for later use. Meanwhile, a 6wt% ferric nitrate precursor solution was prepared by weighing ferric nitrate nonahydrate and dissolving it in deionized water, stirring at room temperature, controlling the stirring speed at 500 rpm / min, and stirring for 8 hours to obtain the transition metal precursor solution for later use. A transition metal-ligand precursor solution was prepared by thoroughly mixing the ligand-melamine with the prepared transition metal precursor solution. The molar ratio of manganese metal to ligand in the transition metal precursor solution was 1:

5. The mixture was stirred thoroughly at 50°C for 5 hours to form a stable transition metal-ligand mixed solution. Step 2: While stirring, pour the transition metal-ligand mixed solution from Step 1 into the 30wt% carbon quantum dot precursor solution from Step 1. After mixing thoroughly, transfer the mixture to a reaction vessel and process it using a solvothermal method at 280℃ in an air atmosphere with a heating rate of 5℃ / min for 6 hours. After natural cooling to room temperature, after the solvothermal reaction is complete, perform a first precision filtration using a 3000-mesh food-grade nylon ultrafine filter, followed by a second precision filtration using a 4000-mesh food-grade nylon ultrafine filter to obtain carbon quantum dot-loaded transition metal single-atom material. The carbon quantum dot-loaded transition metal single-atom material is an iron metal single-atom material loaded with carbon quantum dots.

3. A method for preparing carbon quantum dot-supported transition metal single-atom materials, characterized in that: Includes the following steps: Step 1: Prepare a 40wt% carbon quantum dot precursor solution. Weigh the carbon quantum dot raw materials citric acid, ascorbic acid, glucose, and sucrose, and mix them in a 1:1:1:1 ratio. Add deionized water and stir at room temperature to dissolve or disperse evenly. Control the stirring speed at 700 rpm / min and stir for 8 hours to obtain the carbon quantum dot precursor solution for later use. Meanwhile, a 6wt% cobalt chloride precursor solution was prepared by weighing cobalt chloride hexahydrate and dissolving it in deionized water, stirring at room temperature, controlling the stirring speed at 600 rpm / min, and stirring for 6 hours to obtain the transition metal precursor solution for later use. A transition metal-ligand precursor solution was prepared by thoroughly mixing the ligand-melamine with the prepared transition metal precursor solution. The molar ratio of cobalt metal to ligand in the transition metal precursor solution was 1:

6. The mixture was stirred thoroughly at 60°C for 5 hours to form a stable transition metal-ligand mixed solution. Step 2: While stirring, pour the transition metal-ligand mixed solution from Step 1 into the 30wt% carbon quantum dot precursor solution from Step 1. After mixing thoroughly, transfer the mixture to a reaction vessel and process it using a solvothermal method at 280℃ in an air atmosphere with a heating rate of 2℃ / min for 8 hours. After natural cooling to room temperature, after the solvothermal reaction is complete, perform a first precision filtration using a 3000-mesh food-grade nylon ultrafine filter, followed by a second precision filtration using a 4000-mesh food-grade nylon ultrafine filter to obtain carbon quantum dot-loaded transition metal single-atom material. The carbon quantum dot-loaded transition metal single-atom material is a cobalt metal single-atom material loaded with carbon quantum dots.

4. A method for preparing carbon quantum dot-supported transition metal single-atom materials, characterized in that: Includes the following steps: Step 1: Prepare a 40wt% carbon quantum dot precursor solution. Weigh the carbon quantum dot raw materials citric acid, ascorbic acid, glucose, and sucrose, and mix them in a 1:1:1:1 ratio. Add deionized water and stir at room temperature to dissolve or disperse evenly. Control the stirring speed at 600 rpm / min and stir for 5 hours to obtain the carbon quantum dot precursor solution for later use. Meanwhile, an 8wt% nickel chloride precursor solution was prepared by weighing nickel chloride hexahydrate and dissolving it in deionized water. The solution was stirred at room temperature with a stirring speed of 700 rpm / min for 8 hours to obtain the transition metal precursor solution for later use. A transition metal-ligand precursor solution was prepared by thoroughly mixing the ligand-o-phenanthroline with the prepared transition metal precursor solution. The molar ratio of nickel metal to ligand in the transition metal precursor solution was 1:

7. The mixture was stirred thoroughly at 80°C for 6 hours to form a stable transition metal-ligand mixed solution. Step 2: While stirring, pour the transition metal-ligand mixed solution from Step 1 into the 40wt% carbon quantum dot precursor solution from Step 1. After mixing thoroughly, transfer the mixture to a reaction vessel and process it using a solvothermal method at 280℃ in an air atmosphere with a heating rate of 5℃ / min for 8 hours. After natural cooling to room temperature, after the solvothermal reaction is complete, perform a first precision filtration using a 3000-mesh food-grade nylon ultrafine filter, followed by a second precision filtration using a 4000-mesh food-grade nylon ultrafine filter to obtain carbon quantum dot-loaded transition metal single-atom material. The carbon quantum dot-loaded transition metal single-atom material is a nickel metal single-atom material loaded with carbon quantum dots.

5. A method for preparing carbon quantum dot-supported transition metal single-atom materials, characterized in that: Includes the following steps: Step 1: Prepare a 20wt% carbon quantum dot precursor solution. Weigh the carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose, proline, and valine, and mix them in a ratio of 1:1:1:1:1:

1. Add deionized water and stir at room temperature to dissolve or disperse evenly. Control the stirring speed at 300 rpm / min and stir for 6 hours to obtain the carbon quantum dot precursor solution for later use. Meanwhile, a 10wt% copper sulfate precursor solution was prepared by weighing copper sulfate pentahydrate and dissolving it in deionized water. The solution was stirred at room temperature with a stirring speed of 800 rpm / min for 10 hours to obtain the transition metal precursor solution for later use. A transition metal-ligand precursor solution was prepared by thoroughly mixing the ligand-disodium ethylenediaminetetraacetate with the prepared transition metal precursor solution. The molar ratio of copper to ligand in the transition metal precursor solution was 1:

8. The mixture was stirred thoroughly at 80°C for 6 hours to form a stable transition metal-ligand mixed solution. Step 2: While stirring, pour the transition metal-ligand mixed solution from Step 1 into the 20wt% carbon quantum dot precursor solution from Step 1. After mixing thoroughly, transfer the mixture to a reaction vessel and process it using a solvothermal method at 280℃ in an air atmosphere with a heating rate of 5℃ / min for 5 hours. After natural cooling to room temperature, after the solvothermal reaction is complete, perform a first precision filtration using a 3000-mesh food-grade nylon ultrafine filter, followed by a second precision filtration using a 4000-mesh food-grade nylon ultrafine filter to obtain carbon quantum dot-loaded transition metal single-atom material. The carbon quantum dot-loaded transition metal single-atom material is a copper metal single-atom material loaded with carbon quantum dots.

6. A method for preparing carbon quantum dot-supported transition metal single-atom materials, characterized in that: Includes the following steps: Step 1: Prepare a 10wt% carbon quantum dot precursor solution. Weigh the carbon quantum dot raw materials citric acid, ascorbic acid, glucose, sucrose, and proline, and mix them in a ratio of 1:1:1:1:

1. Add deionized water, stir at room temperature to dissolve or disperse evenly, control the stirring speed at 400 rpm / min, and stir for 6 hours to obtain the carbon quantum dot precursor solution for later use. Meanwhile, a 10wt% zinc chloride precursor solution was prepared by weighing zinc chloride and dissolving it in deionized water, stirring at room temperature, controlling the stirring speed at 800 rpm / min, and stirring for 12 hours to obtain the transition metal precursor solution for later use. A transition metal-ligand precursor solution was prepared by thoroughly mixing the ligand-dimethylimidazole with the prepared transition metal precursor solution. The molar ratio of zinc metal to ligand in the transition metal precursor solution was 1:

6. The mixture was stirred thoroughly at 70°C for 4 hours to form a stable transition metal-ligand mixed solution. Step 2: While stirring, pour the transition metal-ligand mixed solution from Step 1 into the 20wt% carbon quantum dot precursor solution from Step 1. After mixing thoroughly, transfer the mixture to a reaction vessel and treat it using a solvothermal method at 280℃ in an air atmosphere with a heating rate of 2℃ / min for 10 hours. After natural cooling to room temperature, after the solvothermal reaction is complete, perform a first precision filtration using a 3000-mesh food-grade nylon ultrafine filter, followed by a second precision filtration using a 4000-mesh food-grade nylon ultrafine filter to obtain carbon quantum dot-loaded transition metal single-atom material. The carbon quantum dot-loaded transition metal single-atom material is a zinc metal single-atom material loaded with carbon quantum dots.

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