Preparation method and application of iron thiophosphite / graphite phase carbon nitride composite material
By preparing iron thiophosphite/graphite carbon nitride composite materials to form a heterojunction, the problems of easy recombination of photogenerated holes and photoelectrons and poor light wave absorption ability of graphite carbon nitride photocatalysts are solved, achieving efficient photocatalytic nitrogen fixation performance and reducing costs.
Patent Information
- Application Number
- CN202310585475.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-05-23
- Publication Date
- 2025-09-19
- Estimated Expiration
- 2043-05-23
AI Technical Summary
Existing graphite-phase carbon nitride photocatalysts have defects such as easy recombination of photogenerated holes and photoelectrons, poor light wave absorption ability, and small specific surface area, which affect their nitrogen fixation efficiency. In addition, the high cost of precious metal-based catalysts limits their application.
Iron thiophosphite/graphite carbon nitride composite materials were prepared by liquid phase exfoliation to form a heterojunction, combining the advantages of FePS3 and CN, optimizing the band structure and interface contact, and improving the utilization rate of photogenerated electrons.
The photocatalytic nitrogen fixation performance has been significantly improved. The visible light catalytic nitrogen fixation efficiency of 1% FePS3-CN is 9.5 times that of bulk CN. The raw materials are cheap, the preparation method is simple, and it has good application prospects.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of nanomaterials, and specifically relates to a preparation method of an iron thiophosphite / graphite phase carbon nitride composite material (mFePS3-CN) and its application in photocatalytic nitrogen fixation. Background Art
[0002] Nitrogen fixation is the second most important reaction in nature, second only to photosynthesis. It ensures the orderly conversion of free nitrogen into absorbable combined nitrogen during the nitrogen cycle. Currently, the Haber process is the predominant nitrogen fixation method, but its harsh reaction conditions result in significant energy consumption and carbon emissions. In contrast, photocatalytic technology utilizes solar energy under mild reaction conditions, achieving green, low-energy nitrogen fixation.
[0003] Graphitic carbon nitride (CN) is a non-metallic photocatalyst widely used in catalytic nitrogen fixation due to its stable physicochemical properties, low cost, and readily available properties. However, conventional CN suffers from drawbacks such as easy recombination of photogenerated holes and photoelectrons, poor absorption of light wavelengths greater than 470 nm, and a small specific surface area, which hinder its nitrogen fixation efficiency. Iron thiophosphite (FePS3), a novel two-dimensional layered material, offers advantages such as high electrical conductivity, the absence of surface hanging states, and the ability to construct van der Waals heterojunctions without the constraints of conventional lattice matching. It holds great promise for applications in catalysis, batteries, and spintronics. In nature, certain prokaryotic microorganisms exhibit efficient nitrogen fixation under the action of nitrogenase. Researchers have discovered that ferritin plays a crucial role in electron transfer during nitrogenase nitrogen fixation, with the transferred electrons primarily originating from the active sites of 4Fe-4S clusters, while P clusters act as bridges for electron transfer from the Fe-S centers to the substrate. This suggests that the interaction between Fe, S, and P elements significantly influences the nitrogen reduction capacity of nitrogenase. Therefore, we speculate that tuning FePS3 could yield a highly active nitrogen fixation catalyst. Furthermore, FePS3 contains the transition metal Fe, which has both unoccupied and occupied d orbitals, which facilitate the "acceptor-donor" mechanism of nitrogen reduction and promote the binding of Fe and N2. However, FePS3 itself exhibits low visible light photocatalytic activity.
[0004] In order to improve the photocatalytic performance of FePS3, researchers have done a lot of modification work, including morphology and structure modulation, electronic structure optimization and the preparation of composite photocatalysts. Among the many means to improve the photocatalytic performance of FePS3, constructing a heterojunction is an important method to optimize the catalytic performance of FePS3. This method can not only comprehensively utilize the advantages of each component, but also improve the separation efficiency of the photogenerated charge of the catalyst. At present, most of the commonly used commercial catalysts are noble metal-based catalysts. Due to their low content in the earth's crust and high cost, the development and application of noble metal-based co-catalysts are limited. In order to address this problem, the present invention uses relatively low-cost FePS3 materials for composite modification, and provides a kind of iron thiophosphite / graphite phase carbon nitride composite material (mFePS3-CN) and its preparation method. The prepared iron thiophosphite / graphite phase carbon nitride composite material has excellent photocatalytic nitrogen fixation performance. Summary of the Invention
[0005] The purpose of the present invention is to provide an iron thiophosphite / graphite phase carbon nitride composite material (mFePS3-CN), a preparation method and its application in photocatalytic nitrogen fixation in order to solve the problems existing in the prior art.
[0006] The present invention is achieved through the following technical solutions:
[0007] (1) The present invention provides a method for preparing an iron thiophosphite / graphite phase carbon nitride composite material, comprising the following steps:
[0008] S1, preparing graphite phase carbon nitride solution and FePS3 solution;
[0009] S2, mixing the graphite phase carbon nitride solution prepared in S1 and the FePS3 solution and stirring them uniformly;
[0010] S3. Filter the mixed solution obtained in S2, wash the solid obtained by filtration, and vacuum dry it to obtain an iron thiophosphite / graphite phase carbon nitride composite material.
[0011] Furthermore, in S1, the concentration of graphite phase carbon nitride in the graphite phase carbon nitride solution is 1-5 g / L.
[0012] Furthermore, in S1, the concentration of FePS3 in the FePS3 solution is 0.1-0.5 g / L.
[0013] Furthermore, in S1, the method for preparing the graphite phase carbon nitride solution is: dispersing the graphite phase carbon nitride in ultrapure water and ultrasonicating for 4 to 10 hours; the method for preparing the FePS3 solution is: dispersing FePS3 in ultrapure water and ultrasonicating for 4 to 10 hours.
[0014] Furthermore, in S2, the mixing volume ratio of the FePS3 solution and the graphite phase carbon nitride solution is 0.01-0.2.
[0015] Furthermore, in S2, the mixing and stirring time is 10 to 24 hours.
[0016] Furthermore, in S3, the drying temperature is 80-100° C., and the drying time is 4-6 hours.
[0017] (2) The present invention also provides an iron thiophosphite / graphite phase carbon nitride composite material prepared by the preparation method described above.
[0018] (3) The present invention also provides the use of the above-mentioned iron thiophosphite / graphite phase carbon nitride composite material in photocatalytic nitrogen fixation.
[0019] Beneficial effects of the present invention:
[0020] (1) In the present invention, graphite carbon nitride (CN) and FePS3 nanosheets are obtained by liquid phase exfoliation, and the two are combined together by van der Waals forces to obtain a CN and FePS3 heterojunction. Among them, the efficiency of visible light photocatalytic nitrogen fixation of 1% FePS3-CN is the highest, which is 9.5 times that of bulk CN. The sheet / sheet composite of CN and FePS3 can not only comprehensively utilize the advantages of CN and CTFs nanosheets, but also has a larger interface contact, which is conducive to charge transfer between interfaces. Further, through interface regulation, the band structure can be adjusted and the contact interface can be optimized, carrier recombination can be suppressed, and the utilization rate of photogenerated electrons can be improved;
[0021] (2) The raw materials of the present invention are inexpensive, the preparation method is simple to operate, and it can be prepared in large quantities. The prepared mFePS3-CN has many active sites, a wide light absorption range, and excellent photocatalytic nitrogen fixation performance. Therefore, the preparation of the photocatalytic nitrogen fixation nanomaterial of the present invention has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 The preparation flow chart of mFePS3-CN composite material;
[0023] Figure 2 This is a comparison chart of the photocatalytic nitrogen fixation effect of mFePS3-CN composite materials;
[0024] Figure 3 This is the Fourier transform infrared spectrum (FTIR) test diagram of mFePS3-CN composite material;
[0025] Figure 4 This is the X-ray diffraction (XRD) test pattern of mFePS3-CN composite material. DETAILED DESCRIPTION
[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.
[0027] The present invention provides an iron thiophosphite / graphite phase carbon nitride composite material (mFePS3-CN), the preparation method of which comprises the following steps:
[0028] Step 1: prepare graphite phase carbon nitride solution and FePS3 solution;
[0029] Urea is thermally polymerized at high temperature to obtain graphite-phase carbon nitride;
[0030] Dispersing graphite phase carbon nitride in ultrapure water and ultrasonicating for 4 to 10 hours to obtain a graphite phase carbon nitride solution;
[0031] Disperse FePS3 in ultrapure water and sonicate for 4 to 10 hours to obtain a FePS3 solution;
[0032] Wherein, in the graphite phase carbon nitride solution, the concentration of graphite phase carbon nitride is 1-5 g / L, and in the FePS3 solution, the concentration of FePS3 is 0.1-0.5 g / L.
[0033] Step 2: Mix the FePS3 solution prepared in step 1 and the graphite phase carbon nitride solution in a volume ratio of 0.01-0.2 and stir for 10-24 hours;
[0034] Step three: Filter the mixed solution obtained in step two, wash the solid obtained by filtration, and vacuum dry it at 80-100°C for 4-6 hours to obtain an iron thiophosphite / graphite phase carbon nitride composite material (mFePS3-CN). The prepared iron thiophosphite / graphite phase carbon nitride composite material can be used for photocatalytic nitrogen fixation.
[0035] Figure 1 Preparation path diagram for mFePS3-CN composite materials.
[0036] Example 1: Preparation of bulk graphite carbon nitride (CN)
[0037] A certain amount of urea was placed in a muffle furnace at 2°C·min -1 The temperature is raised to 450-550°C at a rate of 0.1°C and maintained at 550°C for 2-4 hours. Finally, it is filtered and washed with ultrapure water and dried at 40-60°C. The obtained light yellow powder solid is g-C3N4, denoted as CN.
[0038] Example 2: Preparation of 0.1% FePS3-CN
[0039] (1) Weigh 1 g of graphite carbon nitride and disperse it in 200 ml of ultrapure water to obtain a graphite carbon nitride solution; disperse 50 mg of FePS3 in 100 ml of ultrapure water to obtain a FePS3 solution;
[0040] (2) ultrasonically treating the two solutions obtained in step (1) at room temperature for 8 h;
[0041] (3) The ultrasonically treated graphite carbon nitride solution and FePS3 solution were mixed at a volume ratio of 100:1 and stirred for 24 h;
[0042] (4) The mixed solution obtained in step (3) was filtered and washed, and then dried under vacuum at 80-100° C. for 6 h to obtain 0.1% FePS3-CN.
[0043] Example 3: Preparation of 0.5% FePS3-CN
[0044] (1) Weigh 1 g of graphite carbon nitride and disperse it in 200 ml of ultrapure water to obtain a graphite carbon nitride solution; disperse 50 mg of FePS3 in 100 ml of ultrapure water to obtain a FePS3 solution;
[0045] (2) ultrasonically treating the two solutions obtained in step (1) at room temperature for 10 h respectively;
[0046] (3) The ultrasonically treated graphite carbon nitride solution and FePS3 solution were mixed at a volume ratio of 20:1 and stirred for 24 h;
[0047] (4) The mixed solution obtained in step (3) was filtered and washed, and then dried under vacuum at 80-100° C. for 4 h to obtain 0.5% FePS3-CN.
[0048] Example 4: Preparation of 1.0% FePS3-CN
[0049] (1) Weigh 1 g of graphite carbon nitride and disperse it in 200 ml of ultrapure water to obtain a graphite carbon nitride solution; disperse 50 mg of FePS3 in 100 ml of ultrapure water to obtain a FePS3 solution;
[0050] (2) ultrasonically treating the two solutions obtained in step (1) at room temperature for 9 h;
[0051] (3) The ultrasonically treated graphite carbon nitride solution and FePS3 solution were mixed at a volume ratio of 10:1 and stirred for 24 h;
[0052] (4) The mixed solution obtained in step (3) was filtered and washed, and then dried under vacuum at 80-100° C. for 6 h to obtain 1.0% FePS3-CN.
[0053] Example 5: Preparation of 1.5% FePS3-CN
[0054] (1) Weigh 1 g of graphite carbon nitride and disperse it in 200 ml of ultrapure water to obtain a graphite carbon nitride solution; disperse 50 mg of FePS3 in 100 ml of ultrapure water to obtain a FePS3 solution;
[0055] (2) ultrasonically treating the two solutions obtained in step (1) at room temperature for 10 h respectively;
[0056] (3) The ultrasonically treated graphite carbon nitride solution and FePS3 solution were mixed at a volume ratio of 6.67:1 and stirred for 24 h;
[0057] (4) The mixed solution obtained in step (3) was filtered and washed, and then dried under vacuum at 80-100° C. for 6 h to obtain 1.5% FePS 3 -CN.
[0058] Example 6: Preparation of 2.0% FePS3-CN
[0059] (1) Weigh 1 g of graphite carbon nitride and disperse it in 200 ml of ultrapure water to obtain a graphite carbon nitride solution; disperse 50 mg of FePS3 in 100 ml of ultrapure water to obtain a FePS3 solution;
[0060] (2) ultrasonically treating the two solutions obtained in step (1) at room temperature for 10 h respectively;
[0061] (3) The ultrasonically processed graphite carbon nitride solution and FePS3 solution were mixed at a volume ratio of 5:1 and stirred for 24 h;
[0062] (4) The mixed solution obtained in step (3) was filtered and washed, and then dried under vacuum at 80-100° C. for 6 h to obtain 2.0% FePS3-CN.
[0063] Example 7: Application of photocatalytic nitrogen fixation of mFePS3-CN
[0064] In this example, the photocatalytic nitrogen fixation performance of the mFePS3-CN prepared in Examples 2 to 6 was evaluated.
[0065] (1) The photocatalytic nitrogen fixation performance of FePS3 nanosheets, bulk CN prepared in Example 1, 0.1% FePS3-CN prepared in Example 2, 0.5% FePS3-CN prepared in Example 3, 1.0% FePS3-CN prepared in Example 4, 1.5% FePS3-CN prepared in Example 5 and 2.0% FePS3-CN composite materials prepared in Example 6 were evaluated by Nessler's reagent colorimetric method (GBT: 7479-87).
[0066] The test method is: ammonia nitrogen in the form of free ammonia or ammonium ions reacts with Nessler's reagent to form a light reddish-brown complex. The absorbance of the complex is proportional to the ammonia nitrogen content, and the absorbance is measured at a wavelength of 420nm.
[0067] Figure 2 These are the effects of photocatalytic nitrogen fixation of bulk CN, 0.1% FePS3-CN, 0.5% FePS3-CN, 1.0% FePS3-CN, 1.5% FePS3-CN, and 2.0% FePS3-CN.
[0068] Depend on Figure 2 As can be seen, mFePS3-CN exhibits a higher yield than CN and FePS3 nanosheets, indicating that the incorporation of FePS3 significantly enhances its photocatalytic activity. Notably, the nitrogen fixation yield of the mFePS3-CN catalyst initially increases and then decreases with increasing FePS3 content, with the optimal FePS3 weight ratio being 1.0 wt.%. This phenomenon can be explained by the fact that the incorporation of an appropriate amount of FePS3 broadens the catalyst's light absorption range and promotes the separation efficiency of photogenerated charge carriers. However, when the amount exceeds 1.0 wt.%, the excess FePS3 covers the CN surface, obscuring CN active sites and thus limiting its photocatalytic performance. Furthermore, the excessive FePS3 content causes excessive fragmentation of the CN structure, leading to increased dissipation of photogenerated charge carriers into vibrational or thermal energy. The yield of 1.0% FePS3-CN is 9.5 times and 2.9 times that of CN nanosheets and FePS3 nanosheets, respectively. This indicates that 1.0% FePS3-CN is the optimal composite material for photocatalytic nitrogen fixation.
[0069] (2) Using Fourier transform infrared spectroscopy (FTIR), the results are as follows Figure 3 As shown, the infrared peaks of all mFePS3-CN samples are consistent with that of CN, 815 cm -1 The peaks that appear represent the characteristic breathing vibrations of the triazine ring, 1000-1800 cm -1 The peaks appearing in the wavenumber range are typical CN heterocyclic unit stretching vibration peaks, 3185-3261 cm -1The characteristic peaks at 400 nm are attributed to the stretching vibration of H2O physically absorbed on the surface of the material or the NH bond at the edge of the aromatic ring defect. This phenomenon indicates that the addition of FePS3 does not significantly change the basic framework of the CN structure.
[0070] (3) X-ray diffraction (XRD) test was used, and the test results were as follows: Figure 4 As shown. CN nanosheets have two obvious characteristic peaks, the peaks at 13.0° and 27.5° correspond to the (100) and (002) crystal planes. The (100) crystal plane represents the ordered arrangement of tri-s-triazine units within the graphite phase carbon nitride plane; the (002) crystal plane represents the interlayer stacking of graphite phase carbon nitride. It is worth noting that the characteristic peaks of FePS3 nanosheets are not observed in the mFePS3-CN composite material, which may be due to the low content and uniform distribution of FePS3 nanosheets. In addition, this phenomenon also shows that the introduction of FePS3 does not destroy the lattice structure of CN nanosheets.
[0071] The above are only preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the scope of protection of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications without departing from the principle of the present invention should be regarded as the scope of protection of the present invention.
Claims
1. A method for preparing an iron thiophosphite / graphite phase carbon nitride composite material, characterized in that: The following steps are involved: S1, preparing graphite phase carbon nitride solution and FePS3 solution; S2, mixing the graphite phase carbon nitride solution prepared in S1 and the FePS3 solution and stirring them uniformly; S3, filtering the mixed solution obtained in S2, washing the solid obtained by filtration, and vacuum drying to obtain an iron thiophosphite / graphite phase carbon nitride composite material; In S1, the concentration of graphite phase carbon nitride in the graphite phase carbon nitride solution is 1-5 g / L; the concentration of FePS3 in the FePS3 solution is 0.1-0.5 g / L; In S2, the mixing volume ratio of FePS3 solution and graphite phase carbon nitride solution is 0.01-0.2; In S1, the preparation method of graphite phase carbon nitride solution is: disperse graphite phase carbon nitride in ultrapure water and ultrasonicate for 4 to 10 hours; the preparation method of FePS3 solution is: disperse FePS3 in ultrapure water and ultrasonicate for 4 to 10 hours.
2. The method for preparing the iron thiophosphite / graphite phase carbon nitride composite material according to claim 1, characterized in that: In S2, the mixing and stirring time is 10~24 h.
3. The method for preparing the iron thiophosphite / graphite phase carbon nitride composite material according to claim 1, characterized in that: In S3, the drying temperature is 80-100°C and the drying time is 4-6h.
4. The iron thiophosphite / graphite phase carbon nitride composite material prepared by the preparation method according to any one of claims 1 to 3.
5. Use of the iron thiophosphite / graphite carbon nitride composite material according to claim 4 in photocatalytic nitrogen fixation.