Silver nanoparticle composite micro-porous carbon spheres, and preparation method and application thereof

Abstract

The present application relates to the technical field of porous carbon material, and particularly discloses silver nanoparticle composite microporous carbon spheres, a preparation method and application thereof.The silver nanoparticle composite microporous carbon spheres are prepared by using ethanolamine as a catalyst, triblock copolymer P123 as a surfactant, and silver nitrate added to the reaction system, and then carbonization is performed to obtain the silver nanoparticle composite microporous carbon spheres.The preparation method is simple, the cost is low, and the yield is high.The silver nanoparticle composite microporous carbon spheres prepared by the present application have a significantly increased specific surface area compared with other types of carbon materials, have a multi-level pore structure, can form a stable conductive network structure by using the strong conductivity and rigidity characteristics, significantly improve the diffusion and transportation rate of carriers, and provide a new idea for developing efficient and inexpensive counter electrode materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of porous carbon materials, and particularly relates to a silver nanoparticle composite microporous carbon sphere and a preparation method and application thereof. BACKGROUND

[0002] In recent years, the third generation of solar cells represented by organic-inorganic hybrid perovskite solar cells brings new opportunities for the development of photovoltaic industry. However, high-efficiency perovskite solar cells usually use Au, Ag and other noble metal materials as the counter electrode, which not only has high cost, but also has poor battery stability, and is difficult to realize industrialized production. Compared with the traditional metal electrode, the porous carbon material is widely available, low in price, and has good electrical conductivity, high specific surface area and mild reaction conditions, and is a counter electrode material with great development potential.

[0003] Although the porous carbon material has obvious advantages as an electrode material, the porous carbon material prepared by the existing synthesis method (such as the template method, the impregnation method, etc.) has a small specific surface area and a low micropore occupancy, which greatly reduces the diffusion and transport rate of the carrier, and at the same time, the preparation process is complex, the yield is low, and to a great extent, the development and application of the porous carbon material are limited. Therefore, it is of great significance to develop a porous carbon material with a large specific surface area and a developed pore structure. SUMMARY

[0004] In view of this, the present application provides a silver nanoparticle composite microporous carbon sphere and a preparation method and application thereof, the composite microporous carbon sphere has a large specific surface area, a rich hierarchical porous structure, excellent electrochemical performance, and at the same time, the preparation method is simple, the cost is low, and the yield is high.

[0005] In order to achieve the above-mentioned application purposes, the present application adopts the following technical solutions:

[0006] In a first aspect, the present application provides a preparation method of a silver nanoparticle composite microporous carbon sphere, comprising the following steps:

[0007] Step one, adding ethanolamine, triblock copolymer P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) and silver nitrate into a mixed solvent of distilled water and anhydrous ethanol in sequence, completely dissolving, then adding a carbon source, stirring to form a carbon source precursor solution;

[0008] Step two, transferring the carbon source precursor solution into a reactor, reacting at 80-120 DEG C for 10-18 hours to obtain a reaction product;

[0009] Step three, sequentially performing centrifugation, washing and vacuum drying on the reaction product to obtain a precursor;

[0010] Step four, sintering, carbonization of the precursor in an inert atmosphere, to obtain the silver nanoparticles composite microporous carbon sphere.

[0011] With respect to the prior art, the preparation method of the silver nanoparticles composite microporous carbon sphere provided by the application can enhance the conductivity of the material, further improve the electrochemical activity, and is conducive to reducing the electrode resistance, thereby providing a strong guarantee for the effective extraction and transmission of carriers. Meanwhile, the use of ethanolamine as a catalyst and triblock copolymer P123 as a surfactant can drive the system to generate a large number of pore structures, ensure the balance symmetry of the molecular system, and thus generate a crosslinked polymer with irregular pore structures. The carbon source precursor solution is reacted at 80-120 DEG C for 10-18 hours, which can provide sufficient active sites for the nucleation of silver nanoparticles and improve the nucleation rate, is conducive to changing the electronic structure and electrochemical properties of the original carbon material, obtaining a more matched energy level distribution, and the specific reaction temperature and time can avoid the crosslinking and agglomeration between the carbon spheres, even the growth into irregular hydrothermal coke. Then, the sintering and carbonization treatment in an inert gas can form pores with similar size and uniform distribution on the surface of the carbon material, greatly improve the porosity, reduce the collapse of the pore wall, and realize the regulation of the size and morphology of the pore structure of the carbon material itself. The silver nanoparticles composite microporous carbon sphere prepared by the application has rich microporous and mesoporous structures, a large specific surface area, a high micropore occupancy rate, can form a stable network structure, optimizes the interface contact quality, effectively improves the hole recombination loss and charge transport capacity.

[0012] Optionally, in step one, the mass ratio of the triblock copolymer P123, silver nitrate and carbon source is 8-10:1:30-37. The preferred ratio realizes the regulation of the composition of the carbon material, can obtain a suitable silver doping amount, thereby improving the conductivity of the carbon material and further improving the performance of the carbon electrode.

[0013] Optionally, in step one, the carbon source is mixed by formaldehyde and furfural with a mass ratio of 7-8:4-5, and the concentration of formaldehyde is 30wt%-40wt%. The preferred carbon source combined with the subsequent processing process can form a multi-stage pore structure, provide more transmission channels and active sites for carriers, shorten the charge transport distance, and obtain better electrochemical performance.

[0014] Optionally, in step one, the volume ratio of distilled water to anhydrous ethanol in the mixed solvent is 5-6:2, the amount of ethanolamine added is catalytic amount, and the amount of carbon source added is 5.4%-9.5% of the mass of ethanol.

[0015] Optionally, in step one, the stirring speed is 700-800 rpm, and the continuous stirring time is 20-28 hours.

[0016] Optionally, in step three, the vacuum drying temperature is 60-100℃, and the vacuum drying time is 6-10h.

[0017] Optionally, in step four, the sintering is programmed heating: heating at a rate of 1-2℃ / min to 150-250℃, holding for 1-2h, then heating at a rate of 3-6℃ / min to 300-400℃, holding for 1-3h, and then continuing to heat at a rate of 3-6℃ / min to 550-750℃, holding for 3-5h.

[0018] The preferred heating rate, temperature and holding time enable the product to steadily undergo dehydration, dehydrogenation and terminal chain decomposition, not only optimizing the porosity, but also enabling the prepared silver nanoparticle composite microporous carbon spheres to have high specific surface area and good hierarchical porous structure, while regulating the silver nanoparticle content of the carbon material within a desired range, ensuring the support strength of the carbon material itself, and improving the yield.

[0019] In a second aspect, the present application provides a silver nanoparticle composite microporous carbon sphere prepared by the above-mentioned method for preparing silver nanoparticle composite microspheres.

[0020] Compared with the prior art, the silver nanoparticle composite microporous carbon sphere provided by the present application utilizes the rigid characteristics and self-supporting of the microporous carbon sphere to form a stable conductive network structure, has uniform pore size distribution and large specific surface area, and the presence of silver nanoparticles can regulate the conductivity of the electrode, effectively improve the charge conduction, and improve the diffusion and transport rate of carriers, thereby providing a new idea for developing efficient and inexpensive counter electrode materials.

[0021] Optionally, the silver nanoparticles are distributed in the microporous carbon spheres to form a core-shell structure of the spherical nanomaterial, and irregular micropores are also distributed on the surface of the microporous carbon spheres.

[0022] In a third aspect, the present application provides an application of the above-mentioned silver nanoparticle composite microporous carbon sphere as a counter electrode in a perovskite solar cell.

[0023] Optionally, the use method of the above-mentioned silver nanoparticle composite microporous carbon sphere as a counter electrode comprises the following steps:

[0024] 1) adding the silver nanoparticle composite microporous carbon sphere and terpineol into a ball mill jar, adding an appropriate amount of ethyl cellulose, ball milling, and fully mixing to obtain a counter electrode;

[0025] 2) sequentially depositing an electron transport layer, a perovskite layer and the above-mentioned counter electrode on a conductive FTO substrate to obtain a perovskite solar cell. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0027] Figure 1 SEM image of silver nanoparticle composite microporous carbon spheres in Example 1 of the present application;

[0028] Figure 2 TEM image of silver nanoparticle composite microporous carbon spheres in Example 1 of the present application;

[0029] Figure 3 XRD image of silver nanoparticle composite microporous carbon spheres in Example 1 of the present application;

[0030] Figure 4 Pore size distribution graph of silver nanoparticle composite microporous carbon spheres in Example 1 of the present application;

[0031] Figure 5 Isothermal nitrogen adsorption-desorption curve graph of silver nanoparticle composite microporous carbon spheres in Example 1 of the present application;

[0032] Figure 6 SEM image of silver nanoparticle composite microporous carbon spheres in Comparative Example 1 of the present application;

[0033] Figure 7 SEM image of silver nanoparticle composite microporous carbon spheres in Comparative Example 5 of the present application;

[0034] Figure 8 Stability test results of perovskite solar cells prepared according to Example 1 of the present application;

[0035] Figure 9 J-V curve graph of perovskite solar cells prepared according to Examples 1-3 of the present application. DETAILED DESCRIPTION

[0036] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0037] Example 1

[0038] The present embodiment provides a preparation method of silver nanoparticle composite microporous carbon spheres, and the specific steps are as follows:

[0039] 1) In a round bottom flask, 8 mL of anhydrous ethanol and 20 mL of distilled water were added, 0.14 mL of ethanolamine, 0.14 g of triblock copolymer P123 and 0.014 g of AgNO3 were added under continuous stirring, after stirring until completely dissolved, 0.2 g of furfural and 0.28 mL of formaldehyde (mass concentration of 35 wt%) were continuously added, the solution became turbid, and stirring was continued at a speed of 750 rpm for 24 h, to obtain a carbon source precursor solution;

[0040] 2) The above carbon source precursor solution was transferred to a reaction kettle, and baked in a 100℃ oven for 14 h to obtain a reaction product, which was then washed by centrifugation with ethanol and vacuum dried at 80℃ for 8 h to obtain a precursor;

[0041] 3) The precursor was sintered in a nitrogen-purged tube furnace, heated to 200℃ at a rate of 1.5℃ / min, kept for 1 h, then heated to 350℃ at a rate of 4℃ / min, kept for 1 h, and then heated to 650℃ at a rate of 5℃ / min, kept for 3 h, and then cooled to room temperature to obtain silver nanoparticle composite microporous carbon spheres.

[0042] Scanning electron microscopy (SEM) characterization found that the surface of the silver nanoparticle composite microporous carbon spheres (CS-Ag) was mottled, and irregular micropores appeared, as shown in Figure 1 Transmission electron microscopy (TEM) characterization found that the solid particles inside the microporous carbon spheres were Ag nanoparticles, which were aggregated in the center of the spheres, as shown in Figure 2 XRD characterization found that the CS-Ag had a broad peak near 23.9° and 43.0°, corresponding to the (002) and (100) characteristic crystal planes of amorphous graphite carbon, while the four strong diffraction peaks at 39.1°, 45.5°, 65.2° and 78.1° corresponded to the (111), (200), (220) and (311) crystal planes of Ag crystals, indicating that Ag elements were successfully doped into the porous carbon material, as shown in Figure 3 The nitrogen isotherm adsorption-desorption curve and pore size distribution obtained by BET testing are shown in Figure 4 , Figure 5 It can be seen that the CS-Ag exists in the H1 hysteresis loop, which is type IV isotherm, reflecting that it is a spherical material with uniform size and narrow pore size distribution, and in addition to the micropore distribution peak, there is also a mesopore distribution peak in the pore size distribution curve of CS-Ag, mainly concentrated near 33.0 nm, which is derived from the stacking of carbon spheres.

[0043] Example 2

[0044] This example provides a method for preparing silver nanoparticle composite microporous carbon spheres, the specific steps are as follows:

[0045] 1) In a round-bottom flask, 7 mL of anhydrous ethanol and 20 mL of distilled water were added, 0.08 mL of ethanolamine, 0.096 g of triblock copolymer P123 and 0.012 g of AgNO3 were added under continuous stirring, after stirring until completely dissolved, 0.14 g of furfural and 0.22 mL of formaldehyde (concentration of 38 wt%) were continuously added, after the solution became turbid, stirring was continued at a speed of 700 rpm for 28 h, and a carbon source precursor solution was obtained;

[0046] 2) The above carbon source precursor solution was transferred to a reaction kettle, which was placed in an 80°C oven and baked for 18 h to obtain a reaction product, which was then centrifuged with ethanol and dried under vacuum at 60°C for 10 h to obtain a precursor;

[0047] 3) The precursor was sintered in a nitrogen-purged tube furnace, heated to 150°C at a rate of 1°C / min, kept for 2 h, then heated to 300°C at a rate of 3°C / min, kept for 2 h, and then heated to 550°C at a rate of 3°C / min, kept for 5 h, and the sample was cooled to room temperature to obtain silver nanoparticle composite microporous carbon spheres.

[0048] Example 3

[0049] The present example provides a method for preparing silver nanoparticle composite microporous carbon spheres, the specific steps are as follows:

[0050] 1) In a round-bottom flask, 8 mL of anhydrous ethanol and 20 mL of distilled water were added, 0.10 mL of ethanolamine, 0.162 g of triblock copolymer P123 and 0.018 g of AgNO3 were added under continuous stirring, after stirring until completely dissolved, 0.22 g of furfural and 0.31 mL of formaldehyde (concentration of 30 wt%) were continuously added, after the solution became turbid, stirring was continued at a speed of 800 rpm for 20 h, and a carbon source precursor solution was obtained;

[0051] 2) The above carbon source precursor solution was transferred to a reaction kettle, which was placed in a 120°C oven and baked for 10 h to obtain a reaction product, which was then centrifuged with ethanol and dried under vacuum at 100°C for 6 h to obtain a precursor;

[0052] 3) The precursor was sintered in a nitrogen-purged tube furnace, heated to 250°C at a rate of 2°C / min, kept for 1 h, then heated to 400°C at a rate of 6°C / min, kept for 1 h, and then heated to 750°C at a rate of 6°C / min, kept for 3 h, and the sample was cooled to room temperature to obtain silver nanoparticle composite microporous carbon spheres.

[0053] Comparative Example 1

[0054] The present comparative example provides a method for preparing silver nanoparticle composite microporous carbon spheres, which differs from Example 1 in that the amount of triblock copolymer P123 is 0.2 g.

[0055] The silver nanoparticle composite micro-porous carbon sphere was found to be spindle-shaped by scanning electron microscopy (SEM), and a large number of small spheres were aggregated around the spindle-shaped spheres, and the uniformity and dispersity were poor, as shown in FIG. 1. Figure 6

[0056] Comparative Example 2

[0057] The present comparative example provides a silver nanoparticle composite microsphere and a preparation method thereof, and the difference from Example 1 is that the amount of the carbon source is 0.64 g, wherein the amount of furfural is 0.25 g, and the amount of formaldehyde (concentration of 35 wt%) is 0.36 mL.

[0058] Comparative Example 3

[0059] The present comparative example provides a silver nanoparticle composite microsphere and a preparation method thereof, and the difference from Example 1 is that the amount of the carbon source is unchanged, wherein the amount of furfural is 0.19 g, and the amount of formaldehyde (concentration of 35 wt%) is 0.18 mL.

[0060] Comparative Example 4

[0061] The present comparative example provides a silver nanoparticle composite microsphere and a preparation method thereof, and the difference from Example 1 is that the baking time is 24 h.

[0062] Comparative Example 5

[0063] The present comparative example provides a silver nanoparticle composite microsphere and a preparation method thereof, and the difference from Example 1 is that the sintering and carbonization procedure is as follows: the temperature is increased to 200℃ at a rate of 4℃ / min, and then the temperature is kept for 2 h; then the temperature is increased to 350℃ at a rate of 4℃ / min, and then the temperature is kept for 2 h; then the temperature is increased to 650℃ at a rate of 5℃ / min, and then the temperature is kept for 4 h; and then the sample is cooled to room temperature to obtain the silver nanoparticle composite micro-porous carbon sphere.

[0064] The silver nanoparticle composite micro-porous carbon sphere was found to be spindle-shaped by scanning electron microscopy (SEM), and a large number of small spheres were aggregated around the spindle-shaped spheres, and the uniformity and dispersity were poor, as shown in FIG. 1. Figure 7

[0065] Performance test

[0066] The silver nanoparticle composite micro-porous carbon spheres (CS-Ag) provided by Examples 1-3 and Comparative Examples 1-5 of the present application were used to prepare perovskite solar cells, and the photoelectric conversion efficiency test results of the prepared perovskite solar cells are shown in Table 1. The preparation method is as follows:

[0067] 1) 0.6 g of CS-Ag and 1.0 g of terpineol were poured into a ball mill jar according to a mass ratio of 3:5, and an appropriate amount of ethyl cellulose was added, and then ball milling was performed for 10 h to obtain a CS-Ag counter electrode.

[0068] ​​2) deposit an electron transport layer, a perovskite layer and a CS-Ag counter electrode on the conductive FTO substrate in sequence to obtain a perovskite solar cell.

[0069] Table 1 photoelectric parameters of perovskite solar cells with different types of carbon spheres as counter electrodes

[0070]

[0071]

[0072] wherein, V oc is an open circuit voltage, J sc is a short circuit current, FF is a fill factor, and PCE is a conversion efficiency.

[0073] As shown in Table 1, the batteries prepared in Examples 1-3 exhibit better electrochemical performance, because the size and morphology of the pore structure of the carbon material itself are controlled by controllable adjustment, the prepared carbon material has a rich pore structure, good uniformity and dispersity, and has a rich and suitable silver doping amount, which improves the conductivity, effectively improves the carbon electrode / perovskite interface contact, optimizes the hole recombination loss and charge transport capacity, the preparation method is simple, the cost is low, and the yield is high; while the carbon material prepared in the comparative example has a single pore structure, poor uniformity and dispersity.

[0074] Figure 8 is a stability test result graph of the perovskite solar cell prepared according to Example 1 of the present application, it can be seen that after 30 days, the energy conversion efficiency (PCE) of the battery decreases from the initial 12.40% to the final 11.22%, maintaining 90.48% of the initial energy conversion efficiency, indicating that the silver nanoparticle composite microspheres prepared by the method provided by the present application have excellent long-term stability; Figure 9 is a J-V curve graph of the perovskite solar cell prepared according to Examples 1-3 of the present application.

[0075] The above only describes the preferred embodiments of the present application and should not be used to limit the present application, any modification, equivalent replacement or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing silver nanoparticle composite micro-porous carbon spheres, characterized in that, The method comprises the following steps: Step one, adding ethanolamine, triblock copolymer P123 and silver nitrate into a mixed solvent of distilled water and anhydrous ethanol in sequence, completely dissolving, then adding a carbon source, stirring to form a carbon source precursor solution; Step two, transferring the carbon source precursor solution into a reactor, reacting at 80-120℃ for 10-18h to obtain a reaction product; Step three, centrifuging, washing and vacuum drying the reaction product in sequence to obtain a precursor; Step four, sintering and carbonizing the precursor in an inert atmosphere to obtain the silver nanoparticle composite microporous carbon sphere.

2. The method for preparing silver nanoparticle composite microporous carbon spheres as described in claim 1, characterized in that, In step one, the mass ratio of the triblock copolymer P123, silver nitrate and the carbon source is 8-10:1:30-37.

3. The method for preparing silver nanoparticle composite microporous carbon spheres as described in claim 1, characterized in that, In step one, the carbon source is a mixture of formaldehyde and furfural with a mass ratio of 7-8:4-5, wherein the concentration of formaldehyde is 30wt%-40wt%.

4. The method for preparing silver nanoparticle composite micro-porous carbon spheres according to claim 1 or 2, characterized in that, In step one, the volume ratio of distilled water to anhydrous ethanol in the mixed solvent is 5-6:2, the amount of ethanolamine added is catalytic amount, and the amount of carbon source added is 5.4%-9.5% of the mass of ethanol.

5. The method for preparing silver nanoparticle composite microporous carbon spheres as described in claim 1, characterized in that, In step one, the stirring speed is 700-800rpm, and the continuous stirring time is 20-28h.

6. The method for preparing silver nanoparticle composite microporous carbon spheres as described in claim 1, characterized in that, In step three, the vacuum drying temperature is 60-100℃, and the vacuum drying time is 6-10h.

7. The method for preparing silver nanoparticle composite microporous carbon spheres as described in claim 1, characterized in that, In step four, the sintering is programmed heating, specifically: heating at a rate of 1-2℃ / min to 150-250℃, holding for 1-2h, then heating at a rate of 3-6℃ / min to 300-400℃, holding for 1-3h, and then continuing to heat at a rate of 3-6℃ / min to 550-750℃, holding for 3-5h.

8. Silver nanoparticle composite micro-porous carbon spheres, characterized in that, The silver nanoparticle composite microporous carbon sphere is prepared by the method of any one of claims 1-7.

9. The silver nanoparticle composite micro-porous carbon sphere of claim 8, wherein, The silver nanoparticles are distributed in the microporous carbon spheres to form a core-shell structure of the spherical nanomaterial, wherein irregular micropores are also distributed on the surface of the microporous carbon spheres.

10. The silver nanoparticle composite microporous carbon sphere of claim 8 as a counter electrode in a perovskite solar cell.

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