Preparation method and application of high-load monatomic catalyst synthesized at low temperature
The preparation of high-load single-atom catalysts through low-temperature synthesis method solves the problems of agglomeration and load uncertainty caused by high-temperature preparation, and achieves high selectivity and low-cost catalyst preparation, which is suitable for electrocatalytic oxygen reduction reactions.
Patent Information
- Application Number
- CN202411361040.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2024-12-20
AI Technical Summary
In the prior art, the preparation of single-atom catalysts at high temperatures is likely to lead to agglomeration, resulting in load uncertainty and high synthesis cost, making it difficult to break through the high load limit of 4 wt%.
Using low-temperature synthesis method, the metal salt solution is slowly dripped into the ligand solution in an oil bath at 50-85°C, oxidant is added and cooled in a cold bath, and washed alternately with anhydrous ethanol and ultrapure water, and finally in a vacuum oven Medium drying to prepare a highly supported single-atom catalyst.
The preparation of a high-load single-atom catalyst is realized, which significantly improves the selectivity of the two-electron oxygen reduction reaction. The process is gentle, the equipment is simple, and it is easy to expand production. It is suitable for electrocatalytic oxygen reduction to produce hydrogen peroxide.
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Figure CN119162610A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of electrocatalyst preparation, and in particular to a preparation method of a low-temperature synthesized high-loaded single-atom catalyst and application thereof. Background Art
[0002] Single atom catalysts (SACs) combine the advantages of heterogeneous and homogeneous catalysts, which can maximize the utilization of atoms. At the same time, they have homogeneous active sites and adjustable electronic environments, which can achieve high catalytic activity and selectivity. They have shown significant application potential in the fields of batteries, pollutant degradation, and synthesis of high value-added chemicals. The loading amount of SACs is closely related to their catalytic performance. However, due to the inherent high surface energy of SACs, they are prone to agglomeration during the preparation process, making it a huge challenge to obtain high-loaded SACs.
[0003] Currently, the most common method for preparing SACs is high-temperature pyrolysis, which is achieved by pyrolyzing metal organic precursors at a temperature >900°C, such as the existing patent CN117427657A.
[0004] However, high temperature exacerbates the agglomeration tendency and synthesis cost of SACs, resulting in uncertainty in the structure and loading amount of SACs; while lowering the reaction temperature makes it difficult for SACs to exceed a high loading amount of 4wt%.
[0005] For example, CN115591547B uses an anchoring method to prepare SACs, but the annealing temperature is still as high as 500-800°C; a high-load Fe SACs (8.3wt%) was synthesized using a low-temperature hydrogenation synthesis method, and the reaction temperature was reduced to 360°C, but explosive hydrogen was required; a room-temperature high-load SACs method can achieve a metal single atom loading of up to 42wt%, and although the environment is mild, it requires the use of expensive laser pulse irradiation equipment. Summary of the invention
[0006] The purpose of the present invention is to provide a method for preparing a low-temperature synthesized high-load single-atom catalyst and its application to solve the problems in the prior art.
[0007] The purpose of the present invention can be achieved by the following technical solutions:
[0008] A method for preparing a low-temperature synthesized high-load single-atom catalyst, the preparation method comprising the following steps:
[0009] S1. Dissolve the ligand material in dimethyl sulfoxide solution and dissolve it evenly by ultrasonication to obtain solution A.
[0010] S2. Add the oxidant to solution A, stir evenly, and place in ice water for cooling.
[0011] S3. Transfer the solution obtained in S2 above into a round-bottom flask and place it in an oil bath.
[0012] S4. Dissolve the metal salt in ultrapure water to obtain solution B.
[0013] S5. Use a rubber-tipped dropper to slowly drip solution B into solution A in S3. After heating at a constant temperature for 5 minutes, add ammonia water or ethanolamine into the round-bottom flask at once. After the reaction is completed, cool the solution and collect it.
[0014] S6. Centrifuge the solution collected in S5, wash it three times alternately with anhydrous ethanol and ultrapure water, and dry it to obtain a single atom catalyst powder.
[0015] Furthermore, the ligand material in S1 is one or two of 2,3,6,7,10,11-hexaminotriphenylene hexahydrochloride, hexaminobenzene trihydrochloride, 1,2,4,5-benzenetetramine tetrahydrochloride, 3,3',4,4'-tetraaminodiphenyl ether, and 3,3',4,4'-tetraaminodiphenylmethane.
[0016] The dimethyl sulfoxide solution is a co-solvent, and the total concentration of the solution after dissolution is 1.5-2 mmol / L.
[0017] Furthermore, the oxidant is one of hydrogen peroxide solution, peracetic acid, concentrated sulfuric acid and a mixture of sodium tungstate.
[0018] Furthermore, the oil bath temperature is 50-85° C., and the stirring heating is performed for 10 minutes. The stirring speed in the preparation method is kept consistent and not less than 50 rad / s.
[0019] Furthermore, the metal salt is one or more of nickel chloride hexahydrate, cobalt nitrate hexahydrate, anhydrous ferrous chloride, cupric chloride dihydrate, and manganese chloride tetrahydrate.
[0020] Furthermore, the slow dripping speed of the B solution in S5 is 0.8-1.4 mL / min, and the volume ratio of the A solution to the B solution is 5:1.
[0021] Furthermore, 80-200 μL of ammonia water or ethanolamine is added to S5 at one time, the temperature is raised to 60° C., and the reaction is stirred and heated at a constant temperature for 12-24 hours.
[0022] Furthermore, the sample washed in S6 is placed in a vacuum oven and vacuum dried at 60° C. for 12 hours.
[0023] Furthermore, the metal single atoms in the single-atom catalyst powder prepared by S6 are one or more of Ni atoms, Co atoms, Fe atoms, Cu atoms, and Mn atoms.
[0024] A method for preparing a low-temperature synthesized high-loaded single-atom catalyst is used to produce a catalyst in the electrocatalytic production of hydrogen peroxide. The high-loaded single-atom catalyst increases the loading of metal single atoms and improves the selectivity of a two-electron oxygen reduction reaction in the process of electrocatalytic oxygen reduction to produce hydrogen peroxide.
[0025] Beneficial effects of the present invention:
[0026] 1. The method for preparing a low-temperature synthesized high-load single-atom catalyst of the present invention can achieve a high load of metal single atoms in the catalyst by adding an oxidant during the preparation process, thereby significantly improving the selectivity of the two-electron oxygen reduction reaction;
[0027] 2. The method for preparing a low-temperature synthesized high-load single-atom catalyst of the present invention has mild experimental conditions, simple equipment, simple process operation, and is easy to achieve further scale-up production. It has good prospects for application in electrocatalytic oxygen reduction to produce hydrogen peroxide and effectively achieves a high single-atom load of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The present invention will be further described below in conjunction with the accompanying drawings.
[0029] Figure 1 is the HADDF-TEM spectrum of the Ni single atom catalyst of the present invention;
[0030] Figure 2 is the EXAFS spectrum of the Ni single atom catalyst of the present invention;
[0031] Figure 3 It is a comparison diagram of the current density of the present invention with the addition of an oxidant and the prior art with no addition of an oxidant;
[0032] Figure 4 It is a performance comparison chart of the invention with the addition of oxidant and the prior art with no addition of oxidant. DETAILED DESCRIPTION
[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0034] A method for preparing a low-temperature synthesized high-load single-atom catalyst, wherein the single atom mentioned is a metal single atom (Ni / Co / Fe / Cu / Mn).
[0035] The preparation method comprises the following steps:
[0036] S1, dissolving the ligand material in a dimethyl sulfoxide solution and dissolving it evenly by ultrasonication to obtain a solution A;
[0037] Wherein, the ligand material can be one or two of 2,3,6,7,10,11-hexamethylenetriphenylene hexahydrochloride (HATP), hexamethylenetrihydrochloride (HAB), 1,2,4,5-benzenetetramine tetrahydrochloride (Y15), 3,3',4,4'-tetraaminodiphenyl ether (ODA), and 3,3',4,4'-tetraaminodiphenylmethane (TADM); the total concentration of the solution after dissolution is 1.5-2mmol / L;
[0038] Among them, dimethyl sulfoxide solution is a co-solvent, and its good solubility helps the ligand material to dissolve quickly.
[0039] S2. Add the oxidant to solution A, stir evenly, and place in ice water for cooling.
[0040] The oxidant is one of hydrogen peroxide solution, peracetic acid, concentrated sulfuric acid and a mixture of sodium tungstate.
[0041] S3. Transfer the solution obtained in S2 above to a round-bottom flask, place it in an oil bath, set the oil bath heating temperature to 50-85°C, stir and heat for 10 minutes, and the stirring speed is 50 rad / s.
[0042] S4, dissolving the metal salt in ultrapure water to obtain solution B;
[0043] Wherein, the metal salt is one or more of nickel chloride hexahydrate, cobalt nitrate hexahydrate, anhydrous ferrous chloride, cupric chloride dihydrate, and manganese chloride tetrahydrate.
[0044] S5. Use a rubber-tipped dropper to slowly drip solution B into solution A in S3 at a rate of 0.8-1.4 mL / min. After heating at a constant temperature for 5 minutes, 80-200 μL of ammonia water or ethanolamine is added to the round-bottom flask at one time, the temperature is raised to 60° C., and the mixture is heated and stirred at a constant temperature for 12-24 hours. After the reaction is completed, the resulting solution is cooled and collected;
[0045] The volume ratio of solution A to solution B is 5:1, and the slow dripping speed ensures that the metal ions are evenly dispersed and quickly electrostatically adsorbed by the hydroxylamine groups in the ligand.
[0046] S6. Centrifuge the solution collected in S5 at 8000 rpm / min for 5 min, then wash it alternately with anhydrous ethanol and ultrapure water for 3 times. Place the obtained sample in a vacuum oven and dry it at 60°C for 12 h to obtain a single atom catalyst powder.
[0047] The stirring speed during the preparation process must not be lower than 50 rad / s and should be kept consistent during the constant temperature heating process to ensure uniform solution temperature.
[0048] Example 1
[0049] In this embodiment, the preparation of Ni single atom catalyst is taken as an example, and the raw materials are HATP, H2O2 solution, and NiCl2·6H2O.
[0050] S1. Dissolve 20 mg of HATP in 20 ml of dimethyl sulfoxide and sonicate for 5 min until it is evenly dissolved. The stirring speed is 50 rad / s to obtain a light yellow solution as solution A.
[0051] The total concentration of the solution after dissolution is 1.8mmol / L.
[0052] S2. Add 2 ml of 50% H2O2 solution into solution A and stir evenly at a stirring speed of 50 rad / s. Put the solution into ice water for cold bath cooling. At this time, the solution turns into a reddish brown solution.
[0053] S3. Transfer the reddish brown solution obtained in S2 to a round-bottom flask, place it in an oil bath, set the oil bath heating temperature to 50°C, stir and heat for 10 minutes, and the stirring speed is 50 rad / s.
[0054] S4. Dissolve 14.205 mg of NiCl2·6H2O in 4 ml of ultrapure water to obtain solution B.
[0055] S5, slowly dripping the B solution into the A solution of S3 at a speed of 0.8 mL / min using a rubber-tipped dropper, heating at a constant temperature for 5 minutes, then adding 80 μL of ammonia water or ethanolamine into the round-bottom flask at once, raising the temperature to 60°C, heating at a constant temperature and stirring for 12 hours, with a stirring speed of 50 rad / s. After the reaction is completed, the obtained solution is cooled and collected;
[0056] The volume ratio of solution A to solution B is 5:1.
[0057] S6. Centrifuge the solution collected in S5 at 8000 rpm / min for 5 min, then wash it alternately with anhydrous ethanol and ultrapure water for 3 times. Place the obtained sample in a vacuum oven and dry it at 60°C for 12 h to obtain a single atom catalyst powder.
[0058] Example 2
[0059] In this embodiment, the preparation of Ni single atom catalyst is taken as an example, and the raw materials are HATP, H2O2 solution, and NiCl2·6H2O.
[0060] S1. Dissolve 13 mg of HATP in 20 ml of dimethyl sulfoxide and sonicate for 5 min until it is evenly dissolved. The stirring speed is 60 rad / s to obtain a light yellow solution as solution A.
[0061] The total concentration of the solution after dissolution is 1.8mmol / L.
[0062] S2. Add 2 ml of 50% H2O2 solution into solution A and stir evenly at a stirring speed of 60 rad / s. Put the solution into ice water for cold bath cooling. At this time, the solution turns into a reddish brown solution.
[0063] S3. Transfer the reddish brown solution obtained in S2 to a round-bottom flask, place it in an oil bath, set the oil bath heating temperature to 65°C, stir and heat for 10 minutes, and the stirring speed is 60 rad / s.
[0064] S4. Dissolve 14.205 mg of NiCl2·6H2O in ultrapure water to obtain solution B.
[0065] S5, slowly dripping the B solution into the A solution of S3 at a rate of 1.3 mL / min using a rubber-tipped dropper, heating at a constant temperature for 5 minutes, then adding 100 μL of ammonia water or ethanolamine into the round-bottom flask at once, raising the temperature to 75°C, heating at a constant temperature and stirring for 18 hours, with a stirring speed of 60 rad / s. After the reaction is completed, the obtained solution is cooled and collected;
[0066] The volume ratio of solution A to solution B is 5:1.
[0067] S6. Centrifuge the solution collected in S5 at 8000 rpm / min for 5 min, then wash it alternately with anhydrous ethanol and ultrapure water for 3 times. Place the obtained sample in a vacuum oven and dry it at 60°C for 12 h to obtain a single atom catalyst powder.
[0068] Example 3
[0069] In this embodiment, the preparation of Ni single atom catalyst is taken as an example, and the raw materials are HATP, H2O2 solution, and NiCl2·6H2O.
[0070] S1. Dissolve 20 mg of HATP in 20 ml of dimethyl sulfoxide and sonicate for 5 min until it is evenly dissolved at a stirring speed of 70 rad / s to obtain a light yellow solution as solution A.
[0071] The total concentration of the solution after dissolution is 1.8mmol / L.
[0072] S2. Add 2 ml of 50% H2O2 solution into solution A and stir evenly at a stirring speed of 70 rad / s. Put the solution into ice water for cold bath cooling. At this time, the solution turns into a reddish brown solution.
[0073] S3. Transfer the reddish brown solution obtained in S2 to a round-bottom flask, place it in an oil bath, set the oil bath heating temperature to 85°C, stir and heat for 10 minutes, and the stirring speed is 70 rad / s.
[0074] S4. Dissolve 14.205 mg of NiCl2·6H2O in ultrapure water to obtain solution B.
[0075] S5, slowly dripping the B solution into the A solution of S3 at a speed of 1.4 mL / min using a rubber-tipped dropper, heating at a constant temperature for 5 minutes, then adding 200 μL of ammonia water or ethanolamine into the round-bottom flask at once, raising the temperature to 80°C, heating and stirring at a constant temperature for 24 hours, with a stirring speed of 70 rad / s. After the reaction is completed, the obtained solution is cooled and collected;
[0076] The volume ratio of solution A to solution B is 5:1.
[0077] S6. Centrifuge the solution collected in S5 at 8000 rpm / min for 5 min, then wash it alternately with anhydrous ethanol and ultrapure water for 3 times. Place the obtained sample in a vacuum oven and dry it at 60°C for 12 h to obtain a single atom catalyst powder.
[0078] The performance of the prepared high-load single atoms was tested, and the results are as follows:
[0079] like Figure 1 Shown is the HADDF-TEM spectrum of the Ni single atom catalyst. The morphology of the catalyst sample prepared by adding an oxidant shows densely distributed bright spots, indicating the presence of abundant Ni single atoms.
[0080] like Figure 2 The EXAFS spectrum of Ni single atom catalyst is shown in An EXAFS peak is seen at , indicating a single-atom structure.
[0081] like Figure 3 As shown in the figure, it is a comparison of the current density with and without the addition of oxidant. Figure 4 As shown, it is a performance comparison chart with and without adding an oxidant. It can be seen that the catalyst prepared by adding an oxidant in this embodiment is transformed from a conductive MOF into a high-load single-atom structure, which is mainly used for electrocatalytic oxygen reduction to produce hydrogen peroxide, and can significantly improve the selectivity of the two-electron oxygen reduction reaction.
[0082] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.
Claims
1. A method for preparing a low-temperature synthesized high-loaded single-atom catalyst, characterized in that: The preparation method comprises the following steps: S1, dissolving the ligand material in a dimethyl sulfoxide solution and dissolving it evenly by ultrasonication to obtain a solution A; S2, add the oxidant to solution A, stir evenly, and put it into ice water for cooling; S3, transfer the solution obtained in S2 above into a round-bottom flask, and place it in an oil bath; S4, dissolving the metal salt in ultrapure water to obtain solution B; S5. Use a rubber-tipped dropper to slowly drip solution B into solution A in S3. After heating at a constant temperature for 5 minutes, add ammonia water or ethanolamine into the round-bottom flask at once. After the reaction is complete, cool the solution and collect it. S6. Centrifuge the solution collected in S5, wash it three times alternately with anhydrous ethanol and ultrapure water, and dry it to obtain a single atom catalyst powder.
2. The method for preparing a low-temperature synthesized high-loaded single-atom catalyst according to claim 1, characterized in that: The ligand material in S1 is one or two of 2,3,6,7,10,11-hexaminotriphenylene hexahydrochloride, hexaminobenzene trihydrochloride, 1,2,4,5-benzenetetramine tetrahydrochloride, 3,3',4,4'-tetraaminodiphenyl ether, and 3,3',4,4'-tetraaminodiphenylmethane; The dimethyl sulfoxide solution is a co-solvent, and the total concentration of the solution after dissolution is 1.5-2 mmol / L.
3. The method for preparing a low-temperature synthesized high-loaded single-atom catalyst according to claim 1, characterized in that: The oxidant is one of hydrogen peroxide solution, peracetic acid, concentrated sulfuric acid and a mixture of sodium tungstate.
4. The method for preparing a low-temperature synthesized high-loaded single-atom catalyst according to claim 1, characterized in that: The oil bath temperature is 50-85° C., and the heating is stirred for 10 minutes. The stirring speed in the preparation method is kept consistent and not less than 50 rad / s.
5. The method for preparing a low-temperature synthesized high-loaded single-atom catalyst according to claim 1, characterized in that: The metal salt is one or more of nickel chloride hexahydrate, cobalt nitrate hexahydrate, anhydrous ferrous chloride, cupric chloride dihydrate, and manganese chloride tetrahydrate.
6. The method for preparing a low-temperature synthesized high-loaded single-atom catalyst according to claim 1, characterized in that: The B solution in the S5 is slowly dripped at a speed of 0.8-1.4 mL / min, and the volume ratio of the A solution to the B solution is 5:
1.
7. The method for preparing a low-temperature synthesized high-loaded single-atom catalyst according to claim 6, characterized in that: 80-200 μL of ammonia water or ethanolamine is added to S5 at one time, the temperature is raised to 60° C., and the mixture is heated and stirred at a constant temperature for 12-24 hours.
8. The method for preparing a low-temperature synthesized high-loaded single-atom catalyst according to claim 1, characterized in that: The sample washed in S6 was placed in a vacuum oven and dried at 60° C. for 12 h.
9. The method for preparing a low-temperature synthesized high-loaded single-atom catalyst according to claim 1, characterized in that: The metal single atoms in the single atom catalyst powder prepared by S6 are one or more of Ni atoms, Co atoms, Fe atoms, Cu atoms, and Mn atoms.
10. Use of the catalyst produced by the method for preparing a low-temperature synthesized high-loaded single-atom catalyst according to any one of claims 1 to 9 in electrocatalytic production of hydrogen peroxide, characterized in that: High-loaded single-atom catalysts increase the loading of metal single atoms and improve the selectivity of the two-electron oxygen reduction reaction in the process of electrocatalytic oxygen reduction to produce hydrogen peroxide.