Carbon-loaded atomic-scale dispersed metal catalyst and preparation method thereof

Abstract

The invention discloses a carbon-loaded atomic-scale dispersion catalyst and a preparation method thereof, and relates to the technical field of electrocatalyst preparation. The invention relates to a preparation method of a carbon-loaded atomic-scale dispersed metal catalyst, which comprises the following steps: (1) ultrasonically dispersing a carbon carrier and deionized water uniformly to obtain a mixed solution A; (2) a metal precursor and deionized water are subjected to ultrasonic dispersion to be uniform, and a metal solution is obtained; and (3) dropwise adding the metal solution into the mixed solution A, heating to 40-80 DEG C, stirring for 300-480 minutes, centrifuging to obtain a product, drying the product, and calcining in inert gas to obtain the carbon-loaded atomic-scale dispersed metal catalyst. The obtained carbon-loaded atomic-scale dispersion catalyst is uniform in distribution and good in conductivity, and is a good electrocatalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a carbon-supported atomic-level dispersed metal catalyst and a preparation method thereof. Background Art

[0002] In recent years, the excessive exploitation and use of fossil energy has produced a large amount of greenhouse gases, causing a series of environmental problems. Therefore, the development of clean and pollution-free new energy has become an urgent and arduous task. At the same time, in order to achieve the "dual carbon" goal proposed by our country, the replacement of fossil energy with renewable energy is the key. Among many new energy sources, such as wind energy, solar energy, tidal energy, etc., hydrogen energy has attracted widespread attention due to its unique advantages. Hydrogen energy has the characteristics of high energy density and a variety of hydrogen production processes. Among them, the green hydrogen production method represented by water electrolysis has achieved "zero carbon emissions", which is in line with the trend of energy development and is the development direction of the future energy industry.

[0003] At present, Pt / C is an excellent commercial electrocatalyst in water electrolysis for hydrogen production. However, the high price of precious metals greatly limits its industrial application. Therefore, the development of low-cost and easy-to-synthesize electrocatalysts has a far-reaching impact on the industrial application of water electrolysis for hydrogen production. In recent years, studies have found that non-precious metal-based catalysts have excellent performance in hydrogen evolution reactions. In addition, atomically dispersed catalysts can not only improve the activity of water electrolysis, but also greatly reduce the cost of catalysts by virtue of their extremely high atomic utilization, unique coordination environment and strong metal-support interaction, and have attracted much attention in electrocatalysis. At the same time, carbon-based materials are one of the most important catalyst carriers, with excellent chemical and mechanical reliability, high electrical conductivity, high specific surface area, low production cost and other characteristics. Therefore, loading atomically dispersed metals on carbon carriers as electrocatalysts can greatly improve hydrogen production efficiency and reduce production costs, which has important practical significance. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a carbon-supported atomically dispersed metal catalyst and a preparation method thereof. The carbon-supported atomically dispersed catalyst obtained by the present invention is uniformly distributed and has good conductivity, and is a good electrocatalyst.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a method for preparing a carbon-supported atomically dispersed metal catalyst, comprising the following steps:

[0007] (1) uniformly dispersing the carbon carrier and deionized water by ultrasonication to obtain a mixed solution A, wherein the concentration of the mixed solution A is 1-5 mg / mL;

[0008] (2) uniformly dispersing the metal precursor and deionized water by ultrasonication to obtain a metal solution, wherein the concentration of the metal solution is 1-4 mg / mL;

[0009] (3) Adding the metal solution dropwise to the mixed solution A, heating to 40-80° C., stirring for 300-480 min, obtaining a product by centrifugation, and drying the product, calcining it in an inert gas to obtain a carbon-supported atomically dispersed metal catalyst.

[0010] In the present invention, if the reaction temperature is too high or too low, the loading effect of the metal catalyst will be affected. If the reaction time is too short, the metal solution and the mixed solution will not react sufficiently, which will easily affect the loading effect of the metal catalyst. Therefore, the present invention is conducive to improving the loading effect of the metal catalyst by controlling the reaction temperature and reaction time.

[0011] Preferably, the carbon carrier in step (1) comprises one of activated carbon, Ketjen black, and BP-2000, and the specific surface area of ​​the carbon carrier is 500-1500m 2 / g, average pore size is 2-50nm, total pore volume is 0.80-4cm 3 / g.

[0012] The present invention enables the carbon carrier to better load the atomic-level dispersed metal catalyst by controlling the specific surface area, average pore diameter and total pore volume of the carbon carrier within the above ranges.

[0013] Preferably, the power of ultrasonic dispersion in step (1) is 160-320 W, and the ultrasonic time is 1-5 min.

[0014] Preferably, the metal in step (2) includes at least one of iron, cobalt, nickel, platinum and rhodium. In addition, cobalt and nickel bimetallics, or iron and cobalt bimetallics may also be loaded simultaneously.

[0015] Preferably, the metal precursor in step (2) is a chloride or a nitrate.

[0016] Preferably, in step (3), the volume ratio of the metal solution to the mixed solution A is 1:(4-20).

[0017] Preferably, the centrifugal speed in step (3) is 5000-9000 rpm, and the centrifugal time is 5-8 min.

[0018] Preferably, in step (3), the product is dried in vacuum at a temperature of 35-60° C. and a vacuum degree of 0.08-0.1 MPa.

[0019] Preferably, the inert gas in step (3) is nitrogen or argon.

[0020] Preferably, during the calcination in step (3), the system needs to be purged with an inert gas first, and the purging time is 60-150 minutes.

[0021] Preferably, in step (3), the heating rate after purging is 5-10°C / min, the calcination temperature is 700-900°C, and is maintained for 100-150 minutes.

[0022] The present invention helps to improve the loading effect of the carbon carrier by controlling the temperature and time during calcination within the above range.

[0023] In a second aspect, the present invention also provides a carbon-supported atomically dispersed metal catalyst prepared by the above method.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The preparation method of the present invention adopts a simple and feasible impregnation method to load atomically dispersed metal catalysts on a carbon carrier. The metal types are various, and the loading amount on the carbon carrier can be accurately controlled by changing the amount of the added metal precursor. According to the X-ray diffraction results, it can be confirmed that there are no crystalline metal particles in the catalyst. TEM, SAED and EDX confirm that the metal on the carbon carrier exists in an atomically dispersed form. The low-cost and easy-to-synthesize catalyst has potential application prospects in water electrolysis reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a transmission electron microscope image of the sample prepared in Example 1.

[0027] Figure 2 This is the X-ray diffraction pattern of the sample obtained in Example 1.

[0028] Figure 3 This is the selected area electron diffraction pattern of the sample obtained in Example 1.

[0029] Figure 4 This is the element distribution diagram of the sample prepared in Example 1.

[0030] Figure 5 This is the X-ray diffraction pattern of the sample obtained in Example 2.

[0031] Figure 6 This is a transmission electron microscope image of the sample obtained in Example 2.

[0032] Figure 7 This is the selected area electron diffraction pattern of the sample obtained in Example 2.

[0033] Figure 8 This is the element distribution diagram of the sample prepared in Example 2.

[0034] Fig. 91 and 2 are hydrogen evolution reaction performance diagrams of Examples 1 and 2.

[0035] Fig.10 This is the X-ray diffraction pattern of the sample obtained in Example 3.

[0036] Fig.11 This is a transmission electron microscope image of the sample prepared in Example 3.

[0037] Fig.12 This is the selected area electron diffraction pattern of the sample obtained in Example 3.

[0038] Fig.13 This is the element distribution diagram of the sample prepared in Example 3.

[0039] Fig.14 This is the X-ray diffraction pattern of the sample obtained in Example 4. DETAILED DESCRIPTION

[0040] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the protection scope and implementation methods of the present invention are not limited thereto.

[0041] Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0042] Example 1

[0043] A method for preparing a carbon-supported atomically dispersed metal catalyst comprises the following steps:

[0044] (1) Weigh 50 mg of activated carbon and place it in 20 mL of deionized water. Ultrasonic dispersion is performed for 5 min at a power of 160 W. Stir at 40 °C for 10 min and mix thoroughly to obtain a mixed solution A. The specific surface area of ​​the activated carbon is 1500 m 2 / g, average pore diameter of 50nm, total pore volume of 4cm 3 / g;

[0045] (2) Weigh 3.5 mg of cobalt chloride and dissolve it in 2 mL of deionized water, and disperse it evenly by ultrasonication to obtain a metal solution;

[0046] (3) adding the metal solution dropwise to the mixed solution A, heating to 40° C., stirring for 300 min, and centrifuging to obtain the product at a speed of 5000 rpm for 5 min;

[0047] (4) drying the product in a vacuum drying oven at a temperature of 35° C. and a vacuum degree of 0.08 MPa;

[0048] (5) Grinding the dried product into powder; then calcining the powder in a nitrogen atmosphere. During calcination, the system needs to be purged with nitrogen for 60 minutes. The calcination temperature is 800°C, the calcination time is 120 minutes, and the heating rate is 5°C / min. Thus, a carbon-supported atomically dispersed cobalt metal catalyst is obtained. The loading amount of the metal catalyst is 3%.

[0049] Figure 1 The transmission electron microscope image of the sample prepared in Example 1 is shown, and no metal particles are observed;

[0050] Figure 2 The X-ray diffraction pattern of the sample prepared in Example 1 is shown, proving that there is no peak of metallic cobalt in the system;

[0051] Figure 3 The selected area electron diffraction pattern of the sample prepared in Example 1 is shown, and only the diffraction rings of activated carbon are present;

[0052] Figure 4 The elemental distribution map of the sample prepared in Example 1 is shown, demonstrating the presence of atomically dispersed cobalt.

[0053] Example 2

[0054] A method for preparing a carbon-supported atomically dispersed metal catalyst comprises the following steps:

[0055] (1) Weigh 50 mg of activated carbon and place it in 20 mL of deionized water. Ultrasonic dispersion is performed for 5 min at a power of 320 W. Stir at 40 °C for 10 min and mix thoroughly to obtain a mixed solution A. The specific surface area of ​​the activated carbon is 1500 m 2 / g, average pore diameter of 50nm, total pore volume of 4cm 3 / g;

[0056] (2) Weigh 1.75 mg of cobalt chloride and dissolve it in 2 mL of deionized water, and disperse it evenly by ultrasonication to obtain a metal solution;

[0057] (3) adding the metal solution dropwise to the mixed solution A, heating to 80° C., stirring for 480 min, and centrifuging to obtain the product at a speed of 9000 rpm for 8 min;

[0058] (4) drying the product in a vacuum drying oven at a temperature of 60° C. and a vacuum degree of 0.1 MPa;

[0059] (5) Grind the dried product area into powder; then calcine the powder in a nitrogen atmosphere. During calcination, the system needs to be purged with nitrogen for 150 minutes. The calcination temperature is 900°C, the calcination time is 150 minutes, and the heating rate is 10°C / min. Thus, a carbon-supported atomically dispersed cobalt metal catalyst is obtained. The loading amount of the metal catalyst is 1.5%.

[0060] Figure 5 The X-ray diffraction pattern of the sample prepared in Example 2 is shown, in which only the diffraction peak of activated carbon exists, and no peak of metallic cobalt exists;

[0061] Figure 6 The transmission electron microscope image of the sample prepared in Example 2 is shown, and no metal particles are observed;

[0062] Figure 7 The selected area electron diffraction pattern of the sample prepared in Example 2 is shown, and only the diffraction rings of activated carbon are present;

[0063] Figure 8 The element distribution diagram of the sample prepared in Example 2 is shown, confirming the presence of cobalt element.

[0064] Fig. 9 The comparison of the hydrogen evolution performance of water electrolysis in an alkaline environment is shown between Example 1 and Example 2. It can be seen that the overpotential of Example 1 is 140 mV, and the overpotential of Example 2 is 217 mV, indicating that the non-precious metal Co has excellent hydrogen evolution activity in an alkaline environment.

[0065] Example 3

[0066] A method for preparing a carbon-supported atomically dispersed metal catalyst is different from that of Example 1 in that the amount of cobalt chloride used in step (2) is 7.0 mg and the loading amount of the metal catalyst is 6%.

[0067] Fig.10 The X-ray diffraction pattern of the sample prepared in Example 3 is shown, in which only the diffraction peak of activated carbon exists, and no peak of metallic cobalt exists;

[0068] Fig.11 The transmission electron microscope image of the sample prepared in Example 3 is shown, and no metal particles are observed;

[0069] Fig.12 The selected area electron diffraction pattern of the sample prepared in Example 3 is shown, and only the diffraction rings of activated carbon are present;

[0070] Fig.13 The elemental distribution map of the sample prepared in Example 3 is shown, confirming the presence of cobalt.

[0071] Example 4

[0072] A method for preparing a carbon-supported atomically dispersed metal catalyst is different from that of Example 1 in that in step (2), the metal precursor cobalt chloride is replaced by nickel chloride in an amount of 3.5 mg, and the mass loading of nickel is 3%.

[0073] Fig.14 The X-ray diffraction pattern of the sample prepared in Example 4 is shown, in which only the diffraction peak of activated carbon is present, and no peak of metallic nickel is present.

[0074] In summary, in the preparation method of the carbon-supported atomically dispersed metal catalyst described in the present invention, the reaction temperature and time, the amount of metal precursor and metal salt, the calcination atmosphere and the calcination temperature are coordinated and cooperated with each other to form a complete technical scheme, which can produce the carbon-supported atomically dispersed metal catalyst required by the present invention.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a carbon-supported atomically dispersed metal catalyst, characterized in that: The following steps are involved: (1) uniformly dispersing the carbon carrier and deionized water by ultrasonication to obtain a mixed solution A, wherein the concentration of the mixed solution A is 1-5 mg / mL; (2) uniformly dispersing the metal precursor and deionized water by ultrasonication to obtain a metal solution, wherein the concentration of the metal solution is 1-4 mg / mL; (3) Adding the metal solution dropwise to the mixed solution A, heating to 40-80° C., stirring for 300-480 min, obtaining a product by centrifugation, and drying the product, calcining it in an inert gas to obtain a carbon-supported atomically dispersed metal catalyst.

2. The method for preparing a carbon-supported atomically dispersed metal catalyst according to claim 1, characterized in that: The carbon carrier in step (1) comprises one of activated carbon, Ketjen black, and BP-2000, and the specific surface area of ​​the carbon carrier is 500-1500m 2 / g, average pore size is 2-50nm, total pore volume is 0.80-4cm 3 / g.

3. The method for preparing a carbon-supported atomically dispersed metal catalyst according to claim 1, characterized in that: The power of ultrasonic dispersion in step (1) is 160-320 W, and the ultrasonic time is 1-5 min.

4. The method for preparing a carbon-supported atomically dispersed metal catalyst according to claim 1, characterized in that: The metal in step (2) includes at least one of iron, cobalt, nickel, platinum and rhodium.

5. The method for preparing a carbon-supported atomically dispersed metal catalyst according to claim 1, characterized in that: The metal precursor in step (2) is a chloride or a nitrate.

6. The method for preparing a carbon-supported atomically dispersed metal catalyst according to claim 1, characterized in that: The centrifugal speed in step (3) is 5000-9000 rpm, and the centrifugal time is 5-8 min.

7. The method for preparing a carbon-supported atomically dispersed metal catalyst according to claim 1, characterized in that: In the step (3), the product is dried in vacuum at a temperature of 35-60° C. and a vacuum degree of 0.08-0.1 MPa.

8. The method for preparing a carbon-supported atomically dispersed metal catalyst according to claim 1, characterized in that: During the calcination in step (3), the system needs to be purged with an inert gas first, and the purging time is 60-150 minutes.

9. The method for preparing a carbon-supported atomically dispersed metal catalyst according to claim 8, characterized in that: In the step (3), the heating rate after purging is 5-10°C / min, the calcination temperature is 700-900°C, and is maintained for 100-150 minutes.

10. The carbon-supported atomically dispersed metal catalyst prepared by the preparation method according to any one of claims 1 to 9.

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