Preparation method and application of guanine-derived coral-like porous carbon material

Abstract

The present application relates to a kind of preparation method of guanine derived coral-like porous carbon material and its application.The present application uses guanine as carbon source and nitrogen source, nickel nitrate hexahydrate as nickel source, and polytetrafluoroethylene dispersion as fluorine source, to prepare coral-like porous carbon material by in-situ self-assembly and high-temperature pyrolysis two-step method.The synthesis method of the present application is simple, raw materials are cheap and easy to obtain, and the specific surface area is large, which combines the advantages of large specific surface area and layered porous structure of biomass materials, so that it has excellent catalytic activity and stability as electrode material for electrocatalytic carbon dioxide (CO2) reduction reaction.

Description

Technical Field

[0001] This invention belongs to the field of porous carbon materials technology, specifically relating to a method for preparing a guanine-derived coral-like porous carbon material and its application. Background Technology

[0002] The dramatic increase in atmospheric CO2 levels has led to environmental problems such as global warming and sea-level rise. Currently, using renewable electricity to reduce CO2 into value-added fuels and chemicals is an effective way to mitigate environmental problems and achieve carbon neutrality. However, the electrocatalytic CO2 reduction reaction is inevitably affected by slow kinetics and a high CO2 activation energy barrier, making the development of catalysts with high selectivity and durability urgently needed.

[0003] Carbon-based catalysts have been widely used as electrode materials for electrocatalytic CO2 reduction due to their good porosity, excellent conductivity, and long-term durability. Layered porous carbon materials are the most promising catalytic supports for CO2 reduction reactions among carbon-based materials. The porous structure of the catalyst can not only enhance CO2 adsorption but also promote mass transport, effectively improving the performance of electrochemical CO2 reduction. Chen et al. prepared 3D porous structures for efficient CO2 electroreduction using a room-temperature salt template antisolvent precipitation strategy (Chen BC, Qi ZJ, Chen B, et al. Angewandte Chemie-International Edition, 2024, 63(1).). Ling et al. obtained porous carbon with abundant intrinsic defects by direct pyrolysis of metal-organic frameworks (Ling LL, Jiao L, Liu XS, et al. Advanced Materials, 2022, 34(42).). However, combined with research analysis, most carbon-based nanomaterial precursors are mainly derived from non-renewable resources, and their synthesis requires harsh high-energy conditions. Furthermore, many existing template methods for synthesizing porous carbon networks are often complex to operate and may damage the original catalytic active sites during post-processing (e.g., template removal under strong acid or strong base conditions).

[0004] The challenge in solving the above problems lies in selecting a suitable carbon source and a simple and highly reproducible preparation method to introduce more catalytically active sites while obtaining a porous structure. Therefore, addressing the shortcomings of existing technologies, this patent application focuses on the renewable bioalkaloid molecule guanine, aiming to develop a new strategy for the green and large-scale preparation of porous carbon materials. A review of current research literature in this field reveals that the preparation method for the porous carbon materials reported in this study is currently unavailable. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing guanine-derived coral-like porous carbon materials and their applications. The preparation method is simple, requires no specific template, uses inexpensive and readily available raw materials, and the prepared carbon materials have a novel coral-like porous structure and good electrocatalytic CO2 reduction activity.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] 1) After mixing the dispersion of guanine, nickel nitrate hexahydrate and polytetrafluoroethylene with an appropriate amount of water, the mixture is stirred evenly at a certain temperature and for a certain time.

[0008] 2) The reacted solution was freeze-dried to obtain the precursor;

[0009] 3) The obtained precursor was carbonized at a certain heating rate in a nitrogen atmosphere, naturally cooled to room temperature, and ground to obtain guanine-derived coral-like porous carbon material.

[0010] Further, in step 1), for every 1 g of guanine added, the amount of nickel nitrate hexahydrate added is 20-90 mg, the amount of polytetrafluoroethylene dispersion (60-62 wt%) added is 6 mL, the amount of water added is 10 mL, the certain temperature is room temperature, and the stirring time is 12 h.

[0011] Furthermore, in step 2), the freeze-drying time is 40 h.

[0012] Further, in step 3), the heating rate is 5. o C / min, carbonization temperature is 800~1000 o C, the high-temperature carbonization time is 2 h.

[0013] The present invention also provides a guanine-derived coral-like porous carbon material prepared by the above preparation method, wherein the porous carbon material forms a controllable structure of a coral-like 3D interconnected porous carbon framework.

[0014] Furthermore, the guanine-derived coral-like porous carbon material is applied to the electrocatalytic CO2 reduction reaction.

[0015] Compared with existing technologies, the advantages of this invention are: the synthesis method is simple, the raw materials are inexpensive and readily available, and the prepared material has a novel structure with abundant pores and a high specific surface area, providing more potential reaction sites and diffusion channels, which is beneficial for mass transfer and surface chemical reactions. When used as a cathode material for electrocatalytic CO2 reduction, it exhibits good electrochemical activity and stability. Attached Figure Description

[0016] Figure 1The images shown are transmission electron microscope (TEM) and scanning electron microscope (SEM) images of the porous carbon material prepared in Example 2.

[0017] Figure 2 The images show the X-ray powder diffraction (XRD) patterns of the porous carbon materials prepared in Examples 1-3.

[0018] Figure 3 The nitrogen adsorption-desorption curves and pore size distribution diagrams of the porous carbon materials prepared in Examples 1-3 are shown.

[0019] Figure 4 The image shows a SEM image of the carbon material prepared in Comparative Example 1.

[0020] Figure 5 The image shows the SEM image of the carbon material prepared in Comparative Example 2.

[0021] Figure 6 Linear scanning voltammetry (LSV) and Faraday efficiency diagrams of the porous carbon materials prepared in Examples 1-3 are shown.

[0022] Figure 7 Linear scan voltammetry (LSV) and Faraday efficiency plots for Example 2 and Comparative Examples 1-2. Detailed Implementation

[0023] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0024] Example 1:

[0025] 1 g of guanine, 60 mg of nickel nitrate hexahydrate, and 6 mL of polytetrafluoroethylene dispersion (60 wt%) were added to 10 mL of water and stirred vigorously at room temperature for 12 h to allow the reaction to proceed fully. The mixture was then freeze-dried for 40 h to obtain the precursor. An appropriate amount of the precursor was weighed and placed in a ceramic boat, then placed in a high-temperature tube furnace and heated at 5000 °C under a nitrogen atmosphere. o Heating to 800°C at a heating rate of C / min o C, hold at this temperature for 2 hours. Allow to cool naturally to room temperature, then grind to obtain a porous carbon material with a coral-like structure. Named Ni. 60 / FNC-800.

[0026] Example 2:

[0027] 1 g of guanine, 60 mg of nickel nitrate hexahydrate, and 6 mL of polytetrafluoroethylene dispersion (60 wt%) were added to 10 mL of water and stirred vigorously at room temperature for 12 h to allow the reaction to proceed fully. The mixture was then freeze-dried for 40 h to obtain the precursor. An appropriate amount of the precursor was weighed and placed in a ceramic boat, then placed in a high-temperature tube furnace and heated at 5000 °C under a nitrogen atmosphere.o Heating to 900°C at a heating rate of C / min o C, hold at this temperature for 2 hours. Allow to cool naturally to room temperature, then grind to obtain a porous carbon material with a coral-like structure. Named Ni. 60 / FNC-900.

[0028] Example 3:

[0029] 1 g of guanine, 60 mg of nickel nitrate hexahydrate, and 6 mL of polytetrafluoroethylene dispersion (60 wt%) were added to 10 mL of water and stirred vigorously at room temperature for 12 h to allow the reaction to proceed fully. The mixture was then freeze-dried for 40 h to obtain the precursor. An appropriate amount of the precursor was weighed and placed in a ceramic boat, then placed in a high-temperature tube furnace and heated at 5000 °C under a nitrogen atmosphere. o Heating to 1000 C / min at a heating rate o C, hold at this temperature for 2 hours. Allow to cool naturally to room temperature, then grind to obtain a porous carbon material with a coral-like structure. Named Ni. 60 / FNC-1000.

[0030] First, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to examine 900... o The morphology and structure of porous carbon materials prepared at pyrolysis temperature C were characterized, such as... Figure 1 As shown, the material has a coral-like porous structure.

[0031] The crystal structures of porous carbon materials prepared at different pyrolysis temperatures were studied using X-ray powder diffraction (XRD), such as... Figure 2 As shown, it can be seen that all samples exhibit two broad diffraction peaks near 26° and 44°, which belong to the (002) and (100) crystal planes of graphite carbon, respectively.

[0032] The specific surface area and pore size distribution characteristics of the samples were analyzed in depth using N2 physical adsorption-desorption tests; for example... Figure 3 As shown in (a), the adsorption-desorption isotherms obtained by the test are all typical type IV, and a clear type H3 hysteresis loop is produced, indicating that a mesoporous structure exists in all of them. Figure 3 The pore size distribution diagram in (b) further confirms that all prepared catalysts possess micro-mesoporous structures. The calculated specific surface area and pore structure parameters of the samples are shown in Table 1, indicating that Ni... 60 / FNC-800, Ni 60 / FNC-900 and Ni 60 The specific surface areas of / FNC-1000 are 363, 354, and 322 m², respectively. 2 / g, and both pore size and pore volume increase with increasing pyrolysis temperature.

[0033] Table 1. Specific surface area and pore structure parameters of porous carbon materials prepared in Examples 1-3

[0034]

[0035] Comparative Example 1:

[0036] 1 g of guanine and 6 mL of polytetrafluoroethylene dispersion (60 wt%) were added to 10 mL of water and stirred vigorously at room temperature for 12 h to allow the reaction to proceed fully. The mixture was then freeze-dried for 40 h to obtain the precursor. An appropriate amount of the precursor was weighed and placed in a ceramic boat, then placed in a high-temperature tube furnace and heated at 500°C under a nitrogen atmosphere. o Heating to 900°C at a heating rate of C / min o C, hold at a constant temperature for 2 hours. Allow to cool naturally to room temperature, then grind to obtain carbon material. Named FNC-900.

[0037] Comparative Example 2:

[0038] 1 g of guanine and 60 mg of nickel nitrate hexahydrate were added to 10 mL of water and stirred vigorously at room temperature for 12 h to allow the reaction to proceed fully. The mixture was then freeze-dried for 40 h to obtain the precursor. An appropriate amount of the precursor was weighed and placed in a ceramic boat, then placed in a high-temperature tube furnace and heated at 500°C under a nitrogen atmosphere. o Heating to 900°C at a heating rate of C / min o C, hold at a constant temperature for 2 hours. Allow to cool naturally to room temperature, then grind to obtain the carbon material. Name it Ni@NC-900.

[0039] The morphology and structure of FNC-900 and Ni@NC-900 were characterized using scanning electron microscopy. Figure 4 SEM images of the FNC-900 show a large number of nanospheres loaded on nanosheets, while Figure 5 The Ni@NC-900 exhibits a two-dimensional rolled-up sheet structure with a smooth surface. These results indicate that the addition of nickel nitrate hexahydrate and polytetrafluoroethylene can both affect the formation of its coral-like morphology.

[0040] Example 6:

[0041] The porous carbon materials prepared at different pyrolysis temperatures in Examples 1-3 were used for the electrocatalytic reduction of CO2 in a CO2-saturated 0.5 M NaHCO3 electrolyte solution. The electrocatalytic performance was tested using a traditional three-electrode system: a catalyst-coated carbon paper as the working electrode, an Ag / AgCl electrode as the reference electrode, and a carbon rod as the counter electrode. The tests were conducted in an H-type electrolytic cell using a Chenhua CHI660e electrochemical workstation. Figure 6 As shown in (a), 900 o Coral-like porous carbon materials obtained from C pyrolysis exhibit the best electrocatalytic CO2 reduction performance. Figure 6 As shown in (b), Ni 60 The / FNC-900 has a CO Faraday efficiency of up to 98.8%.

[0042] from Figure 7 As can be seen from the LSV plot in (a), at the same potential, Ni 60 The current density of the / FNC-900 catalyst is significantly higher than that of Ni@NC-900 and FNC-900, indicating that Ni 60 / FNC-900 exhibits better electrocatalytic CO2 reduction activity, meaning that coral-like porous carbon materials are more conducive to the electrocatalytic CO2 reduction reaction than sheet-like and nanosheet-supported spherical particles. Figure 7 The Faraday efficiency plot in (b) further confirms this point. The maximum CO Faraday efficiencies of Ni@NC-900 and FNC-900 are 73.4% and 84.6%, respectively, which are much lower than those of Ni. 60 / FNC-900.

[0043] In summary, the guanine-derived coral-like porous carbon material prepared in this invention has a high specific surface area and abundant interconnected pore structure, which significantly enhances CO2 adsorption, promotes electron transport, and effectively improves its electrochemical CO2 reduction performance.

[0044] The embodiments described above are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a guanine-derived coral-like porous carbon material, characterized in that, Includes the following steps: 1) After mixing the dispersion of guanine, nickel nitrate hexahydrate and polytetrafluoroethylene with an appropriate amount of water, the mixture is stirred evenly at a certain temperature and for a certain time. 2) The reacted solution was freeze-dried to obtain the precursor; 3) The obtained precursor was carbonized at a certain heating rate in a nitrogen atmosphere, naturally cooled to room temperature, and ground to obtain guanine-derived coral-like porous carbon material. In step 1), for every 1 g of guanine added, the amount of nickel nitrate hexahydrate added is 20-90 mg, the amount of polytetrafluoroethylene dispersion added is 6 mL, and the amount of water added is 10 mL. The concentration of the polytetrafluoroethylene dispersion is 60-62 wt%.

2. The method for preparing a guanine-derived coral-like porous carbon material according to claim 1, characterized in that, In step 1), the specified temperature is room temperature, and the stirring time is 12 hours.

3. The method for preparing a guanine-derived coral-like porous carbon material according to claim 1, characterized in that, In step 2), the freeze-drying time is 40 h.

4. The method for preparing a guanine-derived coral-like porous carbon material according to claim 1, characterized in that, In step 3), the certain heating rate is 5 o C / min.

5. The method for preparing a guanine-derived coral-like porous carbon material according to claim 1, characterized in that, In step 3), the high-temperature carbonization temperature is 800~1000℃. o C.

6. The method for preparing a guanine-derived coral-like porous carbon material according to claim 1, characterized in that, In step 3), the high-temperature carbonization time is 2 hours.

7. A guanine-derived coral-like porous carbon material prepared by the method described in any one of claims 1-6.

8. The application of the guanine-derived coral-like porous carbon material as described in claim 7 in the fabrication of an electrode for electrocatalytic CO2 reduction reaction.

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