Carbonized aerogel nonmetal defect carbon material as well as preparation method and application thereof
By lyophilizing and calcining, a carbonized aerogel non-metal defective carbon material with high specific surface area and surface tunability was prepared, which solved the problem of poor electrocatalytic performance of existing carbon-based catalysts and achieved efficient catalytic performance in oxygen reduction reaction.
Patent Information
- Application Number
- CN202510159778.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-13
- Publication Date
- 2025-05-16
AI Technical Summary
The electrocatalytic performance of existing carbon-based catalysts is not as good as that of noble metal catalysts, and lacks effective synthesis methods and in-depth understanding of the activity center, limiting the catalytic activity of undoped carbon nanomaterials.
By lyophilizing and high-temperature calcining, a carbonated aerogel non-metal defective carbon material with large specific surface area and surface adjustability was prepared.
The structural flexibility and efficient catalytic properties of non-metallic carbon materials are achieved, especially in oxygen reduction reactions, with potential as a self-supporting carbon material.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to a carbonized aerogel non-metal defect carbon material and a preparation method thereof, as well as application of the carbonized aerogel in catalyzing oxygen reduction reactions. Background Art
[0002] The increasingly serious environmental pollution and energy crisis have become the most serious problems facing human society, and green clean energy technologies are urgently needed. So far, the most commonly used catalysts in energy conversion devices such as fuel cells are still precious metal catalysts, but precious metal catalysts have the limitations of scarce resources, high prices, poor stability and poor toxicity.
[0003] Carbon-based materials have attracted extensive research attention due to their advantages such as environmental friendliness, low cost, flexible structure, strong atomic / molecular adjustability, and resistance to acid and alkali media. Despite these advantages, the electrocatalytic performance of pure carbon materials directly used is far inferior to that of precious metal-based catalysts. The addition of heteroatoms and / or transition metal atoms to the carbon matrix can trigger a significant improvement in the electrocatalytic activity of carbon-based catalysts. For heteroatom-doped carbon, it has been reported that doping heteroatoms (such as N, S, P, and B, etc.) in the carbon lattice can effectively improve the electrochemical performance of the carbon lattice. The improvement in electrocatalytic activity is mainly due to the redistribution of the charge density of the carbon skeleton caused by the incorporation of heteroatoms with different electronegativity. Specifically, heteroatoms break the integrity of the π-bonding of the carbon plane and sequentially optimize the charge state of adjacent carbon atoms, making them potential active sites. In addition, transition metal-nitrogen-carbon (MNC) compounds such as single-atom transition metal-doped (Fe, Co, Mn, etc.) catalysts have also been developed. Their excellent electrocatalytic performance is usually attributed to the appropriate adsorption / desorption behavior on the abundant Mx-Ny active sites.
[0004] At present, with the deepening of understanding, people have found that the catalytic activity of undoped carbon nanomaterials can also be greatly improved by rationally regulating the inherent carbon defects in the carbon framework. According to the second law of thermodynamics, there is no defect-free crystalline material, and this law also applies to carbon nanomaterials. Despite significant progress, the traditional "trial and error" method still faces great challenges for further development due to the lack of precise synthesis methods and in-depth understanding of active centers and potential electrocatalytic mechanisms. Therefore, the development of efficient non-metallic carbon-based defective materials is imminent. It is of great significance to precisely construct non-metallic carbon materials with different curvatures and carbon defects by regulating the raw materials for synthesizing carbon aerogels and the thickness of carbon aerogels. Summary of the invention
[0005] The present invention aims to provide a carbonized aerogel non-metallic defect carbon material and its preparation method and application. The present invention adopts freeze drying and high temperature calcination method, which can reasonably adjust the curvature and defects of the carbon material, so that the non-metallic carbon material has a flexible structure, large specific surface area, surface adjustability and other advantages. In addition, the process and equipment of the present invention are simple, energy consumption and cost are low, and it is easy to mass produce.
[0006] The technical solution of the present invention is as follows:
[0007] A method for preparing a carbonized aerogel non-metal defect carbon material comprises the following steps:
[0008] S1: Mix orthosilicate compound, KH560 and deionized water to form silicon precursor; dissolve gelatin (G) in deionized water to obtain gelatin solution; mix inorganic salt, ammonium polyphosphate and deionized water to obtain suspension; add silicon precursor to the gelatin solution, stir at 60-80°C (preferably 65°C) for 1-3h (preferably 2h), then add the suspension, stir and mix to obtain homogeneous precursor, freeze-dry and vacuum dry to obtain product GT-AZn;
[0009] Specifically, orthosilicate compound and KH560 are added to deionized water, stirred at 65° C. for 5 hours to form a silicon precursor (white suspension); gelatin is added to deionized water, stirred at 60-80° C. (preferably 60° C.) for 2 hours to obtain a gelatin solution;
[0010] Preferably, the mass ratio of orthosilicate compound, KH560, gelatin, inorganic salt and ammonium polyphosphate is 2.2-4.4:1-2:3.2:2:2;
[0011] The preferred orthosilicate compound is ethyl orthosilicate;
[0012] The inorganic salt is a zinc salt, for example, selected from one or more of zinc chloride, zinc sulfate, zinc nitrate, zinc carbonate, zinc phosphate, and zinc borate, preferably zinc borate or zinc chloride, particularly preferably zinc borate;
[0013] Specifically, the obtained homogeneous precursor is injected into a mold, frozen in a refrigerator or liquid nitrogen (preferably liquid nitrogen), then placed in a freeze dryer for freeze drying for 10 to 12 hours (preferably 12 hours), and then placed in a vacuum oven at 60 to 80° C. (preferably 60° C.) for 8 to 12 hours (preferably 8 hours) to obtain the product GT-AZn;
[0014] Freeze dryer setting conditions: -60℃, 20pa;
[0015] The mold has different depths, such as 3, 5, 7, 9, 11, 13 mm, preferably 5 mm;
[0016] S2: placing the GT-AZn obtained in S1 into a tubular furnace, calcining it at 700-900° C. (preferably 900° C.) for 2-3 h (preferably 2 h) in a protective atmosphere, and cooling it at room temperature to obtain the carbonized aerogel non-metal defect carbon material;
[0017] The protective atmosphere can be nitrogen or argon.
[0018] The invention relates to a carbonized aerogel non-metal defect carbon material prepared by the preparation method.
[0019] The carbonized aerogel non-metal defect carbon material of the present invention can be used as a catalyst in oxygen reduction reaction.
[0020] The key point of the present invention is that after freeze drying, the carbonized aerogel non-metallic material with a certain curvature and high hardness is formed by calcination in a tubular furnace. The material has excellent ORR performance and has the potential to be used as a self-supporting carbon material.
[0021] Compared with the prior art, the present invention has the following beneficial effects:
[0022] 1. The raw materials used are easily available, the preparation method is simple, and the repeatability is good, which is conducive to the large-scale production of non-metallic carbon-based defect catalysts.
[0023] 2. The obtained material can be used as an electrocatalyst for the oxygen reduction reaction (ORR) of fuel cells.
[0024] 3. The defects and curvature of non-metallic carbon materials can be regulated by freeze-drying and high-temperature calcination, revealing the surface tunability. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 : XRD diagram of Example 1 of the present invention.
[0026] Figure 2 : SEM image of embodiment 1 of the present invention.
[0027] Figure 3 : TEM image of Example 1 of the present invention.
[0028] Figure 4 : HRTEM image of Example 1 of the present invention.
[0029] Figure 5 : LSV diagram of Example 1 of the present invention.
[0030] Figure 6 : LSV performance curve of ORR of Example 2 of the present invention in 0.1M KOH solution.
[0031] Figure 7: LSV performance curve of ORR of Example 3 of the present invention in 0.1M KOH solution.
[0032] Figure 8 : LSV performance curve of ORR of Example 4 of the present invention in 0.1M KOH solution.
[0033] Fig. 9 : LSV performance curve of ORR of Example 5 of the present invention in 0.1M KOH solution.
[0034] Fig.10 : LSV performance curve of ORR of Example 6 of the present invention in 0.1M KOH solution.
[0035] Fig.11 : LSV performance curve of ORR of Example 7 of the present invention in 0.1M KOH solution.
[0036] Fig.12 : LSV performance curve of ORR of Example 8 of the present invention in 0.1M KOH solution.
[0037] Fig.13 : LSV performance curve of ORR of Example 9 of the present invention in 0.1M KOH solution.
[0038] Fig.14 : LSV performance curve of ORR of Example 10 of the present invention in 0.1M KOH solution.
[0039] Fig.15 : LSV performance curve of ORR of Example 11 of the present invention in 0.1M KOH solution.
[0040] Fig.16 : LSV performance curve of ORR of Example 12 of the present invention in 0.1M KOH solution. DETAILED DESCRIPTION
[0041] The present invention is further described below by means of specific embodiments, but the protection scope of the present invention is not limited thereto.
[0042] Example 1
[0043] TEOS (4.4 g) and KH560 (2 g) were added to 7 mL of deionized water and then stirred at 65 ° C for 5 h to form a silicon precursor. At the same time, gelatin was dissolved in 50 mL of deionized water at 60 ° C and stirred for 2 h to obtain a 6 wt.% gelatin solution. Zinc borate (2 g) and ammonium polyphosphate (2 g) were mixed with 50 mL of deionized water under stirring to obtain a uniform suspension. The silicon precursor was then added dropwise to the 6 wt.% G solution and continued to be stirred at 65 ° C for 2 h. The above suspension was then added to the mixed solution and continued to be stirred. The obtained homogeneous precursor was injected into a mold (depth 5 mm) and then directionally frozen in liquid nitrogen. Then it was placed in a freeze dryer for drying. Finally, it was reacted at 60 ° C for 8 h in a vacuum oven to remove excess water and obtain an aerogel sample. The obtained sample was named GT-AZn. Three 5 mm thick samples were placed in a porcelain boat and heated at 900 °C (reaction heating rate 5 °C min -1 ) conditions. The reaction time was 120 minutes. The product was obtained after cooling at room temperature.
[0044] The crystal phase analysis is as follows:
[0045] The crystalline phase of Example 1 was analyzed using powder X-ray diffraction (XRD). The results are as follows: Figure 1 Only the characteristic peak of carbon was found, and no other diffraction peaks were found, indicating that no other metals were present in Example 1.
[0046] The surface analysis is as follows:
[0047] The surface morphology of the material was observed using a scanning electron microscope (SEM). Figure 2 It can be observed that Example 1 has a compact porous structure.
[0048] Transmission electron microscopy analysis is as follows:
[0049] The surface of the material was observed using a transmission electron microscope (TEM). Figure 3 The lamellar porous structure indicates that the aerogel in Example 1 is well carbonized.
[0050] The surface of the material was further observed using a high-resolution transmission electron microscope (TEM). Figure 4 As shown in Figure 1, there are many curved stripes, indicating the formation of curvature.
[0051] Electrochemical performance test:
[0052] Preparation of catalyst ink: 5 mg of catalyst sample was dispersed in 700 μL of deionized water, 250 μL of ethanol, and 50 μL of Nafion (5 wt %) to form a catalyst ink.
[0053] Electrochemical tests were performed using a conventional three-electrode electrochemical workstation (CHI 760E), with a Pt wire as the counter electrode, a glassy carbon electrode as the working electrode, and an Ag-AgCl (saturated potassium chloride solution) electrode as the reference electrode.
[0054] All potentials were calibrated relative to the reversible hydrogen electrode (RHE) by the following calculation: E(vs. RHE) = E(vs. Ag-AgCl) + 0.222 + 0.059 pH All polarization curves were corrected with 95% IR compensation.
[0055] The linear sweep voltammetry curve LSV was performed with 0.1M KOH solution as the electrolyte. Figure 5 As shown, it can be seen that the half-wave potential of Example 1 is 0.76 V, which has a higher alkaline oxygen reduction performance.
[0056] Example 2
[0057] The other operations were the same as in Example 1, except that 1 g of KH560 was added.
[0058] The LSV performance diagram of ORR is shown in Figure 6 , its half-wave potential is 0.72V.
[0059] Example 3
[0060] The other operations were the same as those in Example 1, except that 2.2 g of ethyl orthosilicate was added.
[0061] The LSV performance diagram of ORR is shown in Figure 7 , its half-wave potential is 0.70V.
[0062] Example 4
[0063] The other operations are the same as those in Example 1, except that the calcination temperature is 800 degrees Celsius.
[0064] The LSV performance diagram of ORR is shown in Figure 8 , its half-wave potential is 0.65V.
[0065] Example 5
[0066] The other operations are the same as those in Example 1, except that the calcination temperature is 700 degrees Celsius.
[0067] The LSV performance diagram of ORR is shown in Fig. 9 , its half-wave potential is 0.66V.
[0068] Example 6
[0069] The other operations are the same as those in Example 1, except that the calcination temperature is 600 degrees Celsius.
[0070] The LSV performance diagram of ORR is shown in Fig.10 , its half-wave potential is 0.65V.
[0071] Example 7
[0072] The other operations are the same as those in Example 1, except that the calcination temperature is 500 degrees Celsius.
[0073] The LSV performance diagram of ORR is shown in Fig.11 , its half-wave potential is 0.65V.
[0074] Example 8
[0075] The other operations are the same as in Example 1, except that the calcined sample is 3 mm. The LSV performance of ORR is shown in Figure 12, and its half-wave potential is 0.73V.
[0076] Example 9
[0077] The other operations are the same as in Example 1, except that the calcined sample is 7 mm. The LSV performance diagram of ORR is shown in Figure 13, and its half-wave potential is 0.75V.
[0078] Example 10
[0079] The other operations are the same as in Example 1, except that the calcined sample is 9 mm. The LSV performance of ORR is shown in Figure 14, and its half-wave potential is 0.75V.
[0080] Embodiment 11
[0081] The other operations are the same as in Example 1, except that the calcined sample is 11 mm. The LSV performance diagram of ORR is shown in Figure 15, and its half-wave potential is 0.73V.
[0082] Example 12
[0083] The other operations are the same as in Example 1, except that the calcined sample is 13 mm. The LSV performance diagram of ORR is shown in Figure 16, and its half-wave potential is 0.73V.
Claims
1. A method for preparing carbonized aerogel non-metallic defect carbon material, characterized in that: The steps include: S1: uniformly mix the orthosilicate compound, KH560 and deionized water to form a silicon precursor; dissolve gelatin in deionized water to obtain a gelatin solution; uniformly mix the inorganic salt, ammonium polyphosphate and deionized water to obtain a suspension; The silicon precursor is added dropwise to the gelatin solution, stirred at 60-80° C. for 1-3 hours, and then the suspension is added, stirred and mixed to obtain a homogeneous precursor, which is freeze-dried and vacuum-dried to obtain the product GT-AZn; The inorganic salt is a zinc salt; S2: The GT-AZn obtained in S1 is placed in a tubular furnace, calcined at 700-900° C. for 2-3 hours in a protective atmosphere, and cooled at room temperature to obtain the carbonized aerogel non-metal defect carbon material.
2. The method for preparing carbonized aerogel non-metal defect carbon material according to claim 1, characterized in that: In S1, the orthosilicate compound is ethyl orthosilicate.
3. The method for preparing carbonized aerogel non-metal defect carbon material according to claim 1, characterized in that: In S1, the inorganic salt is selected from one or more of zinc chloride, zinc sulfate, zinc nitrate, zinc carbonate, zinc phosphate, and zinc borate.
4. The method for preparing carbonized aerogel non-metal defect carbon material according to claim 1, characterized in that: In S1, orthosilicate compounds and KH560 are added to deionized water and stirred at 65°C for 5 hours to form a silicon precursor.
5. The method for preparing carbonized aerogel non-metal defect carbon material according to claim 1, characterized in that: In S1, gelatin is added into deionized water and stirred at 60-80°C for 2h to obtain a gelatin solution.
6. The method for preparing carbonized aerogel non-metal defect carbon material according to claim 1, characterized in that: In S1, the mass ratio of the orthosilicate compound, KH560, gelatin, inorganic salt, and ammonium polyphosphate is 2.2-4.4:1-2:3.2:2:
2.
7. The method for preparing carbonized aerogel non-metal defect carbon material according to claim 1, characterized in that: In S1, the obtained homogeneous precursor is injected into a mold, frozen in a refrigerator or liquid nitrogen, and then placed in a freeze dryer for freeze drying for 10 to 12 hours, and then placed in a vacuum oven at 60 to 80° C. for 8 to 12 hours to obtain the product GT-AZn; The setting conditions of the freeze dryer are -60℃, 20pa.
8. The carbonized aerogel non-metal defect carbon material obtained by the preparation method according to any one of claims 1 to 7.
9. Use of the carbonized aerogel non-metal defect carbon material as claimed in claim 8 as a catalyst in oxygen reduction reaction.