Preparation method of non-metallic b and f doped carbon nitride material and application thereof in photocatalytic nitrogen fixation
By preparing nonmetallic B and F-doped carbon nitride photocatalysts, the problems of electron-hole pair recombination and active site differences in the photocatalytic nitrogen fixation process were solved, realizing efficient photocatalytic nitrogen fixation and ammonia synthesis, which has broad application prospects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LIAONING UNIVERSITY
- Filing Date
- 2024-12-31
- Publication Date
- 2026-07-14
AI Technical Summary
Existing carbon nitride photocatalysts suffer from problems such as rapid photoinduced electron-hole pair recombination, poor active sites, and weak charge migration pathways during photocatalytic nitrogen fixation, resulting in low actual photocatalytic efficiency and making large-scale application difficult.
A nonmetallic boron and fluorine doping method was used to prepare a boron trifluoride and fluorine diethyl ether-melamine mixture by stirring in dichloromethane and then calcining at high temperature, thereby improving the separation efficiency of photogenerated electrons and holes.
It significantly improves the light absorption capacity and photocatalytic performance of the photocatalyst, increases ammonia production, is low in cost and simple to operate, and is suitable for large-scale promotion and use.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to a method for preparing non-metallic B and F doped carbon nitride materials and their application in photocatalytic nitrogen fixation. Background Technology
[0002] Nitrogen makes up up to 78% of the atmosphere and is an essential element for almost all life forms on Earth. Nitrogen and its compounds have a wide range of applications in daily life and production.
[0003] Ammonia, as a carrier of green energy and a raw material in agriculture, industry, and medicine, cannot be adequately addressed by natural nitrogen fixation alone. The Haber-Bosch reaction represents a significant achievement in artificial nitrogen fixation technology worldwide. The Haber-Bosch reaction is carried out under high temperature and pressure conditions, consuming a large amount of energy and producing substantial amounts of carbon dioxide. The N≡N bond energy in nitrogen gas reaches as high as 972 kJ·mol⁻¹. -1 Therefore, the search for efficient, low-energy-consumption, and clean nitrogen fixation and ammonia synthesis methods has become a research hotspot in recent years.
[0004] Photocatalytic nitrogen fixation is a novel technology that utilizes solar energy to reduce N2 to NH3 under mild reaction conditions, and it has broad application prospects. Carbon nitride (Cnitride) is a key research focus in photocatalytic nitrogen fixation due to its physicochemical stability, low cost, environmental friendliness, simple processing, suitable bandgap, and tunable electronic properties. However, the actual photocatalytic efficiency of Cnitride is significantly inhibited in large-scale applications due to the rapid recombination of photoinduced electron-hole pairs, poor active sites, and weak charge migration pathways. To address these issues, methods such as elemental doping (S, O, P, B), introducing defects or vacancies, morphology control, and heterojunction design have been used to modify Cnitride. Notably, the doping of non-metallic elements can effectively regulate the electronic structure and surface properties of materials while maintaining their thermal stability and metal-free characteristics.
[0005] Therefore, we will use non-metallic B and F-doped carbon nitride photocatalysts for photocatalytic nitrogen fixation. The preparation method of carbon nitride materials is simple and is a technical problem that urgently needs to be solved. Summary of the Invention
[0006] The purpose of this invention is to synthesize ammonia using a low-energy, low-cost, and green method, and to design a non-metallic B and F-doped carbon nitride photocatalyst for photocatalytic nitrogen fixation.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0008] A nonmetallic B and F-doped carbon nitride material is prepared by the following steps:
[0009] 1) Add boron trifluoride diethyl ether dropwise into dichloromethane, then add melamine and stir until the dichloromethane solvent has completely evaporated;
[0010] 2) The solid obtained in step 1) is calcined at high temperature and then ground to obtain B and F doped carbon nitride powder.
[0011] Furthermore, in the above-mentioned method for preparing a non-metallic B and F doped carbon nitride material, in step 1), the stirring is carried out continuously at room temperature for 5-8 hours.
[0012] Furthermore, in the above-mentioned method for preparing a non-metallic B and F doped carbon nitride material, in step 1), the molar ratio of boron trifluoride ether and melamine is (1, 3, 5, 7, 9, 11, 13):100.
[0013] Furthermore, in the above-mentioned method for preparing a non-metallic B and F doped carbon nitride material, in step 2), the calcination temperature is 550℃, the holding time is 5h, and the heating rate is 5℃ / min.
[0014] The application of non-metallic B and F-doped carbon nitride materials described above in photocatalytic nitrogen fixation.
[0015] The beneficial effects of this invention are:
[0016] 1. This invention combines melamine with boron trifluoride diethyl ether by calcination to obtain a non-metallic B and F-doped carbon nitride photocatalyst. This catalyst is then used for photocatalytic nitrogen fixation and ammonia synthesis, which greatly improves the separation efficiency of photogenerated electrons and holes, enhances light absorption capacity, and strengthens photocatalytic performance.
[0017] 2. The method for preparing non-metallic B and F-doped carbon nitride of the present invention has simple operation steps, mild reaction conditions, and is environmentally friendly, which is conducive to large-scale promotion and use.
[0018] 3. The non-metallic B and F-doped carbon nitride prepared by this invention is inexpensive and has stable properties.
[0019] 4. The non-metallic B and F-doped carbon nitride photocatalyst prepared in this invention exhibits high catalytic activity for ammonia synthesis, with a maximum ammonia yield of 466.92 μmol·L⁻¹. -1 It has broad application prospects. Attached Figure Description
[0020] Figure 1 This is a flowchart illustrating the preparation of non-metallic B and F-doped carbon nitride materials according to the present invention.
[0021] Figure 2 The images show the XRD patterns of nonmetallic B and F-doped carbon nitride obtained in Examples 1-7 and carbon nitride obtained in Example 8 of this invention.
[0022] Figure 3 The images show the FTIR spectra of nonmetallic B and F-doped carbon nitride obtained in Examples 1-7 and carbon nitride obtained in Example 8 of this invention.
[0023] Figure 4 XPS images of nonmetallic B and F-doped carbon nitride obtained in Example 6 and carbon nitride obtained in Example 8 of this invention.
[0024] Figure 5 The nitrogen fixation curves of the non-metallic B and F doped carbon nitride materials obtained in Examples 1-7 and the carbon nitride material obtained in Example 8 under xenon lamp irradiation are shown.
[0025] Figure 6 This diagram illustrates the photocatalytic nitrogen fixation mechanism of the non-metallic B and F-doped carbon nitride materials prepared in this invention. Detailed Implementation
[0026] The present invention will be described in detail below with reference to embodiments, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following embodiments.
[0027] according to Figure 1 The flowchart shown illustrates the preparation of nonmetallic B and F-doped carbon nitride materials.
[0028] Example 1
[0029] A method for preparing a nonmetallic B and F-doped carbon nitride material includes the following steps:
[0030] 1) Add 210 μL of boron trifluoride diethyl ether to 50 mL of dichloromethane, then add 10 g of melamine, and stir at room temperature for 5-8 h until the dichloromethane solvent has completely evaporated;
[0031] 2) The white solid obtained in step 1) is placed in a muffle furnace and heated at 5°C / min. -1 The temperature was raised to 550℃ and calcined for 5 hours. After cooling to room temperature, the mixture was ground to obtain B and F-doped carbon nitride powder (1% BF-CN).
[0032] Example 2
[0033] A method for preparing a nonmetallic B and F-doped carbon nitride material includes the following steps:
[0034] 1) Add 630 μL of boron trifluoride diethyl ether to 50 mL of dichloromethane, then add 10 g of melamine, and stir at room temperature for 5-8 h until the dichloromethane solvent has completely evaporated;
[0035] 2) The white solid obtained in step 1) is placed in a muffle furnace and heated at 5°C / min. -1The temperature was raised to 550℃ and calcined for 5 hours. After cooling to room temperature, the mixture was ground to obtain B and F-doped carbon nitride powder (3% BF-CN).
[0036] Example 3
[0037] A method for preparing a nonmetallic B and F-doped carbon nitride material includes the following steps:
[0038] 1) Add 1050 μL of boron trifluoride diethyl ether to 50 mL of dichloromethane, then add 10 g of melamine, and stir at room temperature for 5-8 h until the dichloromethane solvent has completely evaporated;
[0039] 2) The white solid obtained in step 1) is placed in a muffle furnace and heated at 5°C / min. -1 The temperature was raised to 550℃ and calcined for 5 hours. After cooling to room temperature, the mixture was ground to obtain B and F-doped carbon nitride powder (5% BF-CN).
[0040] Example 4
[0041] A method for preparing a nonmetallic B and F-doped carbon nitride material includes the following steps:
[0042] 1) Add 1470 μL of boron trifluoride diethyl ether to 50 mL of dichloromethane, then add 10 g of melamine, and stir at room temperature for 5-8 h until the dichloromethane solvent has completely evaporated;
[0043] 2) The white solid obtained in step 1) is placed in a muffle furnace and heated at 5°C / min. -1 The temperature was raised to 550℃ and calcined for 5 hours. After cooling to room temperature, the mixture was ground to obtain B and F-doped carbon nitride powder (7% BF-CN).
[0044] Example 5
[0045] A method for preparing a nonmetallic B and F-doped carbon nitride material includes the following steps:
[0046] 1) Add 1890 μL of boron trifluoride diethyl ether to 50 mL of dichloromethane, then add 10 g of melamine, and stir at room temperature for 5-8 h until the dichloromethane solvent has completely evaporated;
[0047] 2) The white solid obtained in step 1) is placed in a muffle furnace and heated at 5°C / min. -1 The temperature was raised to 550℃ and calcined for 5 hours. After cooling to room temperature, the mixture was ground to obtain B and F-doped carbon nitride powder (9% BF-CN).
[0048] Example 6
[0049] A method for preparing a nonmetallic B and F-doped carbon nitride material includes the following steps:
[0050] 1) Add 2310 μL of boron trifluoride diethyl ether to 50 mL of dichloromethane, then add 10 g of melamine, and stir at room temperature for 5-8 h until the dichloromethane solvent has completely evaporated;
[0051] 2) The white solid obtained in step 1) is placed in a muffle furnace and heated at 5°C / min. -1 The temperature was raised to 550℃ and calcined for 5 hours. After cooling to room temperature, the mixture was ground to obtain B and F-doped carbon nitride powder (11% BF-CN).
[0052] Example 7
[0053] A method for preparing a nonmetallic B and F-doped carbon nitride material includes the following steps:
[0054] 1) Add 2730 μL of boron trifluoride diethyl ether to 50 mL of dichloromethane, then add 10 g of melamine, and stir at room temperature for 5-8 h until the dichloromethane solvent has completely evaporated;
[0055] 2) The white solid obtained in step 1) is placed in a muffle furnace and heated at 5°C / min. -1 The temperature was raised to 550℃ and calcined for 5 hours. After cooling to room temperature, the mixture was ground to obtain B and F-doped carbon nitride powder (13% BF-CN).
[0056] Example 8
[0057] Carbon nitride is prepared using the following steps:
[0058] 1) Add 10g of melamine to 50mL of dichloromethane and stir at room temperature for 5-8 hours until the dichloromethane solvent is completely evaporated. Place the resulting solid in a muffle furnace and heat at 5℃·min. -1 Heat to 550℃ and calcine for 5 hours;
[0059] 2) After cooling to room temperature, grind the yellow blocky solid obtained after calcination into powder.
[0060] Examples 1-8 were characterized by XRD and XPS to identify product composition and crystal form.
[0061] Figure 2 The images show the XRD patterns of nonmetallic B and F-doped carbon nitride obtained in Examples 1-7 and carbon nitride obtained in Example 8.
[0062] Figure 3 The images show the FTIR spectra of nonmetallic B and F-doped carbon nitride obtained in Examples 1-7 and carbon nitride obtained in Example 8.
[0063] Figure 4The XPS images of the nonmetallic B and F-doped carbon nitride obtained in Example 6 and the carbon nitride obtained in Example 8 show that B and F elements were successfully incorporated into the carbon nitride.
[0064] The photocatalytic nitrogen fixation test procedure is as follows: Photocatalytic nitrogen fixation is carried out in a photocatalytic reactor. 50 mg of non-metallic B and F-doped carbon nitride catalyst is weighed and added to 100 mL of a methanol-water solution (containing 5% methanol by volume), and ultrasonically dispersed for 15 min. In a dark environment, high-purity nitrogen gas is introduced for 30 min, then the xenon lamp light source is turned on. Samples are manually taken every 30 min, and the concentration of ammonia generated is tested using Nessler's reagent.
[0065] Figure 5 The graphs show the nitrogen fixation curves of the non-metallic B and F doped carbon nitride materials obtained in Examples 1-7 and the carbon nitride material obtained in Example 8 under xenon lamp irradiation.
[0066] Figure 6 This diagram illustrates the photocatalytic nitrogen fixation mechanism of the non-metallic B and F-doped carbon nitride materials prepared in this invention.
[0067] The results show that this invention successfully prepared a non-metallic B and F-doped carbon nitride photocatalyst using boron trifluoride diethyl ether, and this material exhibits excellent photocatalytic nitrogen fixation performance. Under full-spectrum irradiation, the photocatalytic nitrogen fixation efficiency can reach 186.77 μmol·L⁻¹. -1 ·h -1 The non-metallic B- and F-doped carbon nitride materials prepared in this invention have great development and application prospects in photocatalytic green ammonia synthesis.
Claims
1. The application of a non-metallic B and F-doped carbon nitride material in photocatalytic nitrogen fixation, characterized in that, The preparation method of the nonmetallic B and F doped carbon nitride material includes the following steps: 1) Add boron trifluoride ether dropwise into dichloromethane, then add melamine. The molar ratio of boron trifluoride ether to melamine is (1, 3, 5, 7, 9, 11, 13):
100. Stir until the dichloromethane solvent is completely evaporated. 2) The solid obtained in step 1) is calcined at 550°C and then ground to obtain B and F doped carbon nitride powder.
2. The application of a non-metallic B and F-doped carbon nitride material according to claim 1 in photocatalytic nitrogen fixation, characterized in that, In step 1), the stirring is performed continuously at room temperature for 5-8 hours.
3. The application of a non-metallic B and F-doped carbon nitride material according to claim 1 in photocatalytic nitrogen fixation, characterized in that, In step 2), the calcination holding time is 5 h and the heating rate is 5 °C / min.