Curvature-adjustable carbon nano hollow sphere carbon functional carrier and preparation method thereof

Abstract

The invention provides a curvature-adjustable carbon nano hollow sphere carbon functional carrier and a preparation method thereof, and the preparation method comprises the following steps: (1) mixing a styrene monomer, an amino-containing monomer, an emulsifier and a co-emulsifier to form a microemulsion; (2) adding an initiator to initiate polymerization; (3) after the reaction is completed, dialyzing and centrifugally purifying to obtain aminated polystyrene nanospheres with good size uniformity; (4) respectively obtaining aminated polystyrene nanospheres with different curvature radiuses by controlling the dosages of the monomer, the emulsifier and the initiator; and (5) performing Joule thermal transient thermal treatment carbonization on the prepared aminated polystyrene nanospheres to obtain a series of carbon nano hollow spheres with different curvatures. The structure prepared by the invention has the characteristics of good particle size uniformity, adjustable curvature radius, anchoring points on the surface and the like, and the preparation method can be used for large-scale synthesis, has good controllability, is simple and feasible, and can provide a reliable process method for synthesis of a functional carbon carrier for loading a metal monatomic catalyst.

Description

Technical Field

[0001] The invention belongs to the field of preparation of novel zero-dimensional nano carbon-based functional materials, in particular to a curvature-adjustable carbon nano hollow spherical carbon functional carrier and a preparation method thereof. Background Art

[0002] Rechargeable zinc-air battery is a new type of energy storage device that combines the advantages of secondary batteries and fuel cells. It has advantages such as theoretical energy density, discharge stability, safety and reliability, strong scalability, and abundant zinc metal reserves that are much higher than those of lithium-ion batteries. Both OER and ORR carried out at the air cathode are multi-electron-proton coupled transfer processes involving the evolution of multiple oxygen-containing intermediates (OH* / O* / OOH*). Their slow kinetics reduce the output voltage during the discharge process and increase the input voltage during the charging process, which seriously limits the charge and discharge efficiency of the device. The development of efficient oxygen electrocatalysts is the key to improving the performance of zinc-air battery devices. Among many catalytic materials, single-atom catalysts have shown great application potential in the field of catalysis due to their theoretical 100% atomic active site utilization, unique electronic structure and geometric structure. However, for supported catalysts, the two dimensions of carrier and anchored active sites can be coordinated to fully understand their complete catalytic reaction mechanism and activity origin, which has practical guiding significance for the precise design of efficient single-atom / nanocluster catalysts. In addition, surface curvature (used to describe the local curvature of the catalytic site) is an important physical property parameter of the carrier, and its synergistic effect on the catalytic performance of the anchoring site has been preliminarily verified at the experimental level, but the optimal curvature value cannot be defined. The reason is that it is difficult to control the synthesis of carriers with different curvatures, and it is impossible to conduct comparative studies to analyze their internal laws. Therefore, the key is to prepare nanocarbon carriers with good size uniformity and adjustable curvature.

[0003] In the present invention, researchers have found a new method for preparing curvature-adjustable carbon nano hollow spheres, whose morphology presents the remarkable feature of uniform particle size, and can realize the complete synthesis of a series of carbon carriers from 200 nanometers to 5 micrometers. The nanostructure shows the characteristics of good size uniformity, adjustable radius of curvature, and the site of anchoring metal atoms on the surface. At present, the method for preparing carbon nano hollow spheres is the template method, which is mainly through the selection of appropriate templates (such as SiO2, PS microspheres, etc.) as the core, and the carbon precursor (such as phenolic resin, glucose, etc.) is coated on the template surface, and then through pyrolysis or carbonization process, the carbon precursor is converted into a carbon shell, and finally the template is removed by pickling or other methods to form a carbon nano hollow sphere. This method template removal process is complicated, impurities may be introduced, and the template cost is high, and the particle size distribution is uneven, and the hollow structure may be incomplete. At the same time, this method is also difficult to realize the large-scale production of carbon functional carriers.

[0004] In order to solve these problems, the present invention proposes a Joule heat transient high temperature pyrolysis carbonization method, using a microemulsion polymerization method, styrene monomer, amino-containing monomer, emulsifier (such as Tween-80) and co-emulsifier (such as n-butanol) are mixed to form a microemulsion, and then an initiator (such as potassium persulfate, KPS) is added to initiate polymerization at a relatively low temperature (such as 50°C). After the reaction is completed, the amino polystyrene nanospheres are obtained by dialysis and centrifugation purification. Then, the amino polystyrene nanospheres are blended with carbon black and heat-treated and carbonized using a Joule heat device to prepare carbon nano hollow spheres, and carbon hollow nanospheres with different curvatures are achieved by using precursors with different particle sizes. The experimental process of the present invention is simple, and carbon-based nano functional carriers can be prepared on a large scale; in addition, the present invention is simple and easy to operate, has good repeatability, and is low in cost, and provides a reliable method for the preparation of carbon functional carriers for metal single atom anchoring. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for preparing a carbon nano hollow spherical carbon functional carrier with adjustable curvature simply, efficiently and easily on a large scale.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A method for preparing a curvature-adjustable carbon nano hollow sphere carrier comprises the following steps:

[0008] (1) 5-10 g of styrene monomer, 0.5-2 g of amino-containing monomer, 0.5-2 g of emulsifier and 1-3 mL of co-emulsifier are mixed to form a microemulsion;

[0009] (2) adding an initiator to initiate polymerization at 40-60 degrees Celsius;

[0010] (3) After the reaction is completed, amino-modified polystyrene nanospheres with uniform size are obtained by dialysis and centrifugation purification;

[0011] (4) by controlling the amounts of monomer, emulsifier, and initiator, amino polystyrene nanospheres with different curvature radii are obtained;

[0012] (5) The amino polystyrene nanospheres prepared above are carbonized by Joule heat transient heat treatment to obtain a series of carbon nano hollow spheres with different curvatures.

[0013] As a preferred embodiment, the emulsifier in step (1) is polyoxyethylene sorbitan monooleate Tween-80, and the co-emulsifier is n-butanol.

[0014] As a preferred embodiment, the amount of initiator added to the polymerization reaction in step (2) is 0.05-0.1 g, and the temperature is controlled at 50 degrees Celsius.

[0015] As a preferred embodiment, the Joule heat treatment temperature in step (5) is 600 Kelvin, the duration is 90 seconds, and the atmosphere is inert argon.

[0016] As a preferred method, the amount of styrene monomer used is 6 g, the amino monomer is 1 g, the initiator is 0.05 g, the reaction time of step (2) is 20 hours, and step (4) produces polystyrene nanospheres with an average particle size of less than 500 nanometers.

[0017] As a preferred method, the amount of styrene monomer used is 6 g, the amino monomer is 1 g, the initiator is 0.06 g, the reaction time of step (2) is 20 hours, and step (4) produces polystyrene nanospheres with an average particle size greater than 500 nanometers and less than 1 micron.

[0018] As a preferred method, the amount of styrene monomer used is 8 g, the amino monomer is 1 g, the initiator is 0.08 g, the reaction time of step (2) is 20 hours, and step (4) produces polystyrene nanospheres with an average particle size greater than 1 micron and less than 5 microns.

[0019] The second object of the present invention is to provide a carbon nano hollow spherical carbon functional carrier with adjustable curvature, which is obtained according to the above preparation method.

[0020] As a preferred embodiment, the morphology of the curvature-adjustable carbon nano hollow sphere carrier is a zero-dimensional nano hollow sphere structure, the sphere particle size is uniform, and amino groups are loaded on the surface.

[0021] As described above, the present invention has the following beneficial effects: the present method utilizes microemulsion polymerization to allow styrene monomer to undergo emulsion polymerization reaction to form surface amino-modified polystyrene nanospheres, and then utilizes Joule heat transient heat treatment carbonization process to obtain a series of curvature carbon nano hollow carbon sphere carriers. The present invention has a simple experimental process and can prepare high-quality carbon-based functional carriers on a large scale; in addition, the present invention is simple and easy to operate, has good repeatability, and is low in cost, and provides a reliable process method for the complete synthesis of carbon functional carriers for metal single atom loading. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A scanning electron micrograph of the curvature-adjustable carbon nano hollow sphere prepared by the present invention;

[0023] Figure 2 The X-ray diffraction spectrum of the curvature-adjustable carbon nano hollow sphere prepared by the present invention;

[0024] Figure 3 The Fourier-infrared spectrum of the curvature-adjustable carbon nano hollow sphere prepared by the present invention;

[0025] Figure 4 Solid-state nuclear magnetic resonance of curvature-adjustable carbon nano hollow spheres prepared by the present invention 13 C spectrum;

[0026] Figure 5 The present invention provides an X-ray photoelectron spectrum of the curvature-adjustable carbon nano hollow sphere prepared by the present invention. DETAILED DESCRIPTION

[0027] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] Example 1

[0029] A method for preparing a curvature-adjustable carbon nano hollow sphere carrier comprises the following steps:

[0030] (1) Styrene monomer, amino-containing monomer, emulsifier and co-emulsifier are mixed to form a microemulsion. The microemulsion in step (1) is prepared with 5-10 g of monomer, 0.5-2 g of amino-containing monomer, emulsifier (such as Tween-80, 0.5-2 g) and co-emulsifier (n-butanol, 1-3 mL);

[0031] (2) adding an initiator to initiate polymerization at 40-60 degrees Celsius. Preferably, the amount of initiator added to the polymerization reaction in step (2) is 0.05-0.1 g, and the temperature is controlled at 50 degrees Celsius;

[0032] (3) After the reaction is completed, amino-modified polystyrene nanospheres with uniform size are obtained by dialysis and centrifugation purification;

[0033] (4) by controlling the amounts of monomer, emulsifier, and initiator, amino polystyrene nanospheres with different curvature radii are obtained;

[0034] Preferably, the amount of styrene monomer used is 6 g, the amino monomer is 1 g, the initiator is 0.05 g, the reaction time of step (2) is 20 hours, and step (4) produces polystyrene nanospheres with an average particle size of less than 500 nanometers.

[0035] Preferably, the amount of styrene monomer used is 6 g, the amino monomer is 1 g, the initiator is 0.06 g, the reaction time of step (2) is 20 hours, and step (4) produces polystyrene nanospheres with an average particle size greater than 500 nanometers and less than 1 micrometer.

[0036] Preferably, the amount of styrene monomer used is 8 g, the amino monomer is 1 g, the initiator is 0.08 g, the reaction time of step (2) is 20 hours, and step (4) produces polystyrene nanospheres with an average particle size greater than 1 micron and less than 5 microns.

[0037] (5) The amino polystyrene nanospheres prepared above are carbonized by Joule heat transient heat treatment to obtain a series of carbon nano hollow spheres with different curvatures. In step (5), the Joule heat treatment temperature is 600 Kelvin, the duration is 90 seconds, and the atmosphere is inert argon gas.

[0038] The curvature-adjustable carbon nano hollow sphere carrier obtained by the above method has a zero-dimensional micro-hollow structure in shape, a curvature radius that can be adjusted from nanometer level to micrometer level, and a surface containing heterogeneous nitrogen elements as functional anchoring points.

[0039] Figure 1 This is a scanning electron micrograph of the curvature-adjustable carbon nano hollow sphere carrier prepared by the present invention. It can be seen that the synthesized carbon carrier presents a spherical microscopic morphology with uniform particle size, and the curvature radius is adjustable from nanometer level to micrometer level.

[0040] Figure 2 This is the X-ray diffraction spectrum of the curvature-adjustable carbon nano hollow sphere carrier prepared in the present invention. It can be seen that the carrier presents the (002) characteristic diffraction peak of carbon.

[0041] Figure 3 The Fourier-infrared spectrum of the curvature-adjustable carbon nano hollow sphere carrier prepared by the present invention clearly shows that the carbon hollow sphere carrier has infrared signals of C=N and NC=N.

[0042] Figure 4 Solid-state nuclear magnetic resonance of the curvature-adjustable carbon nano hollow sphere carrier prepared by the present invention 13 C spectrum verifies that the treated carbon hollow sphere carrier has an infrared signal of NC=N.

[0043] Figure 5 The X-ray photoelectron spectrum of the curvature-adjustable carbon nano hollow sphere carrier prepared by the present invention verifies that the treated carbon hollow sphere carrier has a nitrogen doping effect and can be used as an anchoring point to capture and anchor metal single atoms.

[0044] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing a curvature-adjustable carbon nano-hollow spherical carbon functional carrier, characterized in that The steps include: (1) 5-10 g of styrene monomer, 0.5-2 g of amino-containing monomer, 0.5-2 g of emulsifier and 1-3 mL of co-emulsifier are mixed to form a microemulsion; (2) adding an initiator to initiate polymerization at 40-60 degrees Celsius; (3) After the reaction is completed, amino-modified polystyrene nanospheres with uniform size are obtained by dialysis and centrifugation purification; (4) by controlling the amounts of monomer, emulsifier, and initiator, amino polystyrene nanospheres with different curvature radii are obtained; (5) The amino polystyrene nanospheres prepared above are carbonized by Joule heat transient heat treatment to obtain a series of carbon nano hollow spheres with different curvatures.

2. The method for preparing the curvature-adjustable carbon nano hollow spherical carbon functional carrier according to claim 1, characterized in that: The emulsifier in step (1) is polyoxyethylene sorbitan monooleate Tween-80, and the co-emulsifier is n-butanol.

3. The method for preparing the curvature-adjustable carbon nano hollow spherical carbon functional carrier according to claim 1, characterized in that: In step (2), the amount of initiator added to the polymerization reaction is 0.05-0.1 g, and the temperature is controlled at 50 degrees Celsius.

4. The method for preparing the curvature-adjustable carbon nano-hollow spherical carbon functional carrier according to claim 1, characterized in that: In step (5), the Joule heat treatment temperature is 600 Kelvin, the duration is 90 seconds, and the atmosphere is inert argon.

5. The method for preparing the curvature-adjustable carbon nano hollow spherical carbon functional carrier according to claim 1, characterized in that: The amount of styrene monomer used is 6 g, the amino monomer is 1 g, the initiator is 0.05 g, the reaction time of step (2) is 20 hours, and the step (4) produces polystyrene nanospheres with an average particle size of less than 500 nanometers.

6. The method for preparing the curvature-adjustable carbon nano hollow spherical carbon functional carrier according to claim 1, characterized in that: The amount of styrene monomer used is 6 g, the amino monomer is 1 g, the initiator is 0.06 g, the reaction time of step (2) is 20 hours, and the step (4) produces polystyrene nanospheres with an average particle size greater than 500 nanometers and less than 1 micrometer.

7. The method for preparing the curvature-adjustable carbon nano hollow spherical carbon functional carrier according to claim 1, characterized in that: The amount of styrene monomer used is 8 g, the amino monomer is 1 g, the initiator is 0.08 g, the reaction time of step (2) is 20 hours, and the step (4) produces polystyrene nanospheres with an average particle size greater than 1 micron and less than 5 microns.

8. A curvature-adjustable carbon nano-hollow spherical carbon functional carrier, characterized in that: Obtained according to the preparation method described in any one of claims 1 to 7.

9. The curvature-adjustable carbon nano-hollow spherical carbon functional carrier according to claim 8, characterized in that: The curvature-adjustable carbon nano hollow sphere carrier has a zero-dimensional nano hollow sphere structure, a uniform sphere particle size, and amino groups are loaded on the surface.

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