A metal atomic cluster-loaded porous carbon framework and its preparation method

Abstract

The present invention relates to the technical field of the preparation of novel nanomaterials, and specifically relates to a metal atomic cluster supported porous carbon framework and a preparation method thereof. First, the solid grinding method is used, with melamine, sodium citrate, and metal salts as raw materials, ground in a mortar for a certain period of time, and then the obtained powder is subjected to high-temperature calcination and acid treatment to obtain MAC / PC. Sodium citrate is the key to forming the porous carbon framework structure. The micro-nano structure has uniform size and complete structure, has a good three-dimensional conductive network, and the metal atomic clusters are well dispersed in the porous carbon framework. Compared with the existing methods for preparing metal atomic clusters, the method of the present invention has the advantages of high efficiency, simple operation, and short process, providing a new way for the large-scale synthesis of metal atomic cluster materials.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of novel nanomaterials, and particularly to a metal atomic cluster-loaded porous carbon framework and a preparation method thereof. Background Art

[0002] The existing forms of metals include bulk, particles and clusters. The application fields of metals include energy, catalysis, etc., and metal-based materials usually exhibit relatively excellent properties. In recent years, with the continuous development of the energy field, metal atomic clusters have gradually attracted wide attention from scientific researchers and are considered ideal candidates to replace other existing forms of metals. At the same time, considering the atom economy theory, metal atomic clusters can achieve the maximum atomic utilization rate. However, it should be noted that metal atomic clusters cannot exist independently and need to be embedded in the carbon-based material framework. Therefore, the efficient synthesis of metal atomic cluster / carbon-based composites has become a research hotspot in the current energy field.

[0003] There are various synthesis routes for metal atomic cluster / carbon-based composites. The main method is to use metal-organic frameworks as precursors and prepare them through high-temperature calcination combined with post-treatment processes. However, the disadvantages of this method are obvious, that is, the synthesis process is relatively complex and a large amount of metal atoms are wasted. So far, no general strategy for large-scale preparation of metal atomic clusters has been found.

[0004] In view of the above defects, the creator of the present invention finally obtained the present invention through long-term research and practice. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems that the synthesis process of the current method for preparing metal atomic cluster / carbon-based composites using metal-organic frameworks as precursors through high-temperature calcination combined with post-treatment processes is relatively complex and a large amount of metal atoms are wasted, and to provide a metal atomic cluster-loaded porous carbon framework and a preparation method thereof.

[0006] To achieve the above purpose, the present invention discloses a preparation method of a metal atomic cluster-loaded porous carbon framework, including the following steps:

[0007] S1, preparing a precursor powder: uniformly mixing melamine and sodium citrate, grinding, adding a metal salt / ethanol solution thereto, and continuing to grind and then drying;

[0008] S2, preparing MAC / PC: transferring the powder dried in step S1 to a tube furnace, introducing an inert gas, setting the tube furnace program, calcining the sample, putting the obtained black powder into a hydrochloric acid solution, heating and stirring, centrifuging, washing and drying the solution, and collecting the powder sample.

[0009] In step S1, the mass ratio of melamine to sodium citrate is 1:10.

[0010] In step S1, sodium citrate is used to obtain the porous carbon framework structure.

[0011] Using a mortar in step S1 is convenient for large-scale preparation and industrialization.

[0012] In step S1, the grinding time is 30 min after mixing melamine and sodium citrate evenly.

[0013] In step S1, ethanol is used as the solvent for the metal salt.

[0014] In step S1, the metal salt / ethanol solution added is 0.1 mol / L, and the grinding time is 1 h after adding the metal salt / ethanol solution.

[0015] In step S1, the drying time is 24 h and the drying temperature is 45 °C.

[0016] The metal salt in step S1 is any one of metal iron salts, metal cobalt salts, and metal nickel salts.

[0017] In step S2, the calcination temperature of the sample is 600 - 800 °C.

[0018] In step S2, the heating rate is 2 °C / min.

[0019] In step S2, the hydrochloric acid solution is 1.0 mol / L hydrochloric acid.

[0020] The present invention also discloses a metal atomic cluster-loaded porous carbon framework prepared by the above preparation method.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The synthesis of the present invention is simple, the method is easy to control, and it is continuously efficient. Compared with other methods for preparing metal atomic clusters / porous carbon frameworks, the present invention uses melamine / sodium citrate / metal salt as the precursor to prepare metal atomic clusters / porous carbon frameworks, providing a new idea for the synthesis of metal atomic clusters, and thus broadening the research field of scientific research work. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 XRD pattern of iron metal clusters / porous carbon in Example 1;

[0023] Figure 2 SEM image of iron metal clusters / porous carbon in Example 1;

[0024] Figure 3 TEM image of iron metal clusters / porous carbon in Example 1;

[0025] Figure 4 Aberration-corrected electron microscopy image of iron metal clusters / porous carbon in Example 1;

[0026] Figure 5 It is the SEM image of cobalt metal clusters / porous carbon in Example 2;

[0027] Figure 6 It is the SEM image of nickel metal clusters / porous carbon in Example 3;

[0028] Figure 7 It is the TEM image of iron metal clusters / porous carbon in the comparative example. Detailed implementation manners

[0029] The following further elaborates on the above and additional technical features and advantages of the present invention with reference to the accompanying drawings.

[0030] Example 1

[0031] First, mix melamine and sodium citrate evenly at a mass ratio of 1:10, then transfer them to a mortar and grind for 30 minutes. Sodium citrate is the key to forming the porous carbon framework structure. Add a certain amount of 0.1 mol / L iron chloride / ethanol solution to it, continue to grind vigorously for 1 hour, then transfer it to a vacuum drying oven and dry at 45°C for 12 hours.

[0032] Transfer the dried powder to a tube furnace, introduce an inert gas, set the tube furnace program, and calcine the sample at 600°C for 2 hours. Subsequently, put the obtained black powder into a hydrochloric acid (1.0 mol / L) solution, heat and stir for 24 hours. After centrifuging, washing, and drying the solution, collect the powder sample.

[0033] Figure 1 It is the XRD pattern of the product iron metal clusters / porous carbon, from Figure 1 it can be seen that there is a carbon material in the iron metal clusters / porous carbon; Figure 2 It is the SEM image of the product iron metal clusters / porous carbon, indicating that the porous carbon material has been successfully prepared Figure 3 It is the TEM image of the product iron metal clusters / porous carbon, from Figure 3 it can be seen that there are no large-size nanoparticles in the iron metal clusters / porous carbon; Figure 4 It is the aberration-corrected electron microscopy image of the product iron metal clusters / porous carbon, from Figure 4 it can be seen that the metal clusters are embedded in the carbon framework.

[0034] Example 2

[0035] First, mix melamine and sodium citrate evenly at a mass ratio of 1:10, then transfer them to a mortar and grind for 30 minutes. Sodium citrate is the key to forming the porous carbon framework structure. Add a certain amount of 0.1 mol / L cobalt chloride / ethanol solution to it, continue to grind vigorously for 1 hour, then transfer it to a vacuum drying oven and dry at 45°C for 12 hours.

[0036] Transfer the dried powder into a tubular furnace, introduce an inert gas, set the tubular furnace program, and calcine the sample at 600 °C for 2 hours. Subsequently, put the obtained black powder into a hydrochloric acid (1.0 mol / L) solution, heat and stir for 24 hours. After centrifuging, washing, and drying the solution, collect the powder sample.

[0037] Figure 5 SEM image of the product metal cobalt clusters / porous carbon, from Figure 5 It can be seen that the metal cobalt clusters / porous carbon obtained in this example has porous characteristics, indicating the successful synthesis of the porous carbon framework.

[0038] Example 3

[0039] First, mix melamine and sodium citrate evenly at a mass ratio of 1:10, and then transfer them into a mortar and grind for 30 minutes. Sodium citrate is the key to forming the porous carbon framework structure. Add a certain amount of 0.1 mol / L nickel chloride / ethanol solution to it, continue to grind vigorously for 1 hour, then transfer it into a vacuum drying oven and dry at 45 °C for 12 hours.

[0040] Transfer the dried powder into a tubular furnace, introduce an inert gas, set the tubular furnace program, and calcine the sample at 600 °C for 2 hours. Subsequently, put the obtained black powder into a hydrochloric acid (1.0 mol / L) solution, heat and stir for 24 hours. After centrifuging, washing, and drying the solution, collect the powder sample.

[0041] Figure 6 SEM image of the product metal nickel clusters / porous carbon, from Figure 6 It can be seen that the metal nickel clusters / porous carbon obtained in this example has porous characteristics, indicating the successful synthesis of the porous carbon framework.

[0042] Comparative Example

[0043] First, mix melamine and sodium citrate evenly at a mass ratio of 1:10, and then transfer them into a mortar and grind for 30 minutes. Sodium citrate is the key to forming the porous carbon framework structure. Add a certain amount of 0.1 mol / L iron chloride / ethanol solution to it, grind for 10 minutes, then transfer it into a vacuum drying oven and dry at 45 °C for 12 hours.

[0044] Transfer the dried powder into a tubular furnace, introduce an inert gas, set the tubular furnace program, and calcine the sample at 600 °C for 2 hours. Subsequently, put the obtained black powder into a hydrochloric acid (1.0 mol / L) solution, heat and stir for 24 hours. After centrifuging, washing, and drying the solution, collect the powder sample.

[0045] Figure 7The TEM image of the product metal iron clusters / porous carbon shows that Figure 7 in this example, what is obtained is metal iron nanoparticles / porous carbon, rather than metal iron clusters, indicating that grinding is crucial for the formation of metal clusters.

[0046] The above are only the preferred embodiments of the present invention, which are illustrative rather than restrictive to the present invention. Those skilled in the art understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, but all will fall within the protection scope of the present invention.

Claims

1. A preparation method of a metal atomic cluster supported porous carbon framework, characterized in that, It includes the following steps: S1. Prepare the precursor powder: Mix melamine and sodium citrate evenly, grind them, add a metal salt / ethanol solution thereto, continue grinding and then dry; S2. Prepare the metal atomic cluster / porous carbon: Transfer the powder dried in step S1 to a tubular furnace, introduce an inert gas, set the tubular furnace program, after calcining the sample, put the obtained black powder into a hydrochloric acid solution, heat and stir, centrifuge, wash and dry the solution, and then collect the powder sample; In step S1, the mass ratio of melamine to sodium citrate is 1:10; In step S1, the added metal salt / ethanol solution is 0.1 mol / L, and the grinding time after adding the metal salt / ethanol solution is 1 h; The metal salt in step S1 is any one of metal iron salts, metal cobalt salts, and metal nickel salts; In step S2, the sample calcination temperature is 600 - 800 °C.

2. The preparation method of a metal atomic cluster supported porous carbon framework according to claim 1, characterized in that, In step S1, the grinding time after mixing melamine and sodium citrate evenly is 30 min.

3. The preparation method of a metal atomic cluster-loaded porous carbon framework according to claim 1, characterized in that, In step S1, the drying time is 24 h and the drying temperature is 45 °C.

4. The preparation method of a metal atomic cluster-loaded porous carbon framework according to claim 1, wherein In step S2, the hydrochloric acid solution is 1.0 mol / L hydrochloric acid.

5. A porous carbon framework loaded with metal atomic clusters prepared by the preparation method according to any one of claims 1 to 4.

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