Preparation method and application of Fe@Fe2O3 / GCN-NSs composite photocatalyst
Thin-film porous carbon nitride prepared by a three-step calcination method is combined with Fe@Fe2O3 to form Fe@Fe2O3/GCN-NSs photocatalyst, which solves the problems of low photocatalytic activity and electron-hole recombination of g-C3N4 and achieves a highly efficient photocatalytic degradation effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-29
- Publication Date
- 2026-03-31
AI Technical Summary
The original graphitic carbon nitride (g-C3N4) has low photocatalytic activity and the photogenerated electron-hole pairs are prone to recombination, which limits its practical application.
Thin-film porous carbon nitride (GCN-NSs) was prepared by a three-step calcination method and reacted with Fe2+ to generate Fe@Fe2O3 composite, forming Fe@Fe2O3/GCN-NSs composite photocatalyst, which increases the specific surface area and charge transfer distance and inhibits photogenerated carrier recombination.
It significantly improves photocatalytic activity, especially the degradation effect on antibiotics under visible light conditions, and the preparation process is simple, environmentally friendly, and low in cost.
Smart Images
Figure CN117753466B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photocatalysis technology, specifically relating to a method for preparing a Fe@Fe2O3 / GCN-NSs composite photocatalyst. Background Technology
[0002] Antibiotics are secondary metabolites produced by microorganisms (including bacteria, fungi, and actinomycetes) or higher plants and animals during their life processes. They possess antipathogenic or other activities and are chemical substances that can interfere with the developmental functions of other living cells. In recent years, large amounts of organic pollutants, including dyes, pesticides, and antibiotics, have flowed into water bodies, harming plants and aquatic organisms and potentially threatening human health. Therefore, it is necessary to adopt certain technological means to address this pollution problem. Solar energy, as one of the main energy sources for sustainable development, can be converted through photovoltaic-assisted electrolysis, photoelectrochemical cells, and photocatalysis. Among these, photocatalysis technology has received widespread attention as a highly efficient method for degrading organic pollutants. Subsequently, a large number of photocatalysts have been developed, mainly based on metal semiconductors, including metal oxides, metal sulfides, metal nitrides, and their complexes. These inorganic metal semiconductors exhibit excellent performance in photocatalysis, but also have some significant drawbacks, such as environmental harm, toxicity, and high cost.
[0003] Carbon nitride (CN4) is a novel photocatalytic material with advantages such as high stability, low cost, and environmental friendliness. With a band gap of approximately 2.7 eV, CN4 can absorb a significant amount of visible light and possesses strong redox capabilities. Therefore, CN4 shows broad application prospects in photocatalytic degradation of organic pollutants, photocatalytic water splitting for hydrogen production, and photocatalytic reduction of carbon dioxide. Graphite-phase CN4 (g-C3N4), as a non-metallic semiconductor, exhibits unique advantages in the field of photocatalytic materials. For example, it is mainly composed of C and N, two abundant elements, resulting in low synthesis costs; its band levels are tunable, it has high chemical stability, abundant N sources at the edges, and is non-toxic and harmless. However, the photocatalytic activity of pristine g-C3N4 is not high, and its relatively low specific surface area is unfavorable for light absorption. Furthermore, the photogenerated electron-hole pairs in pristine g-C3N4 recombine easily, hindering photoreactions and severely limiting its practical applications. Summary of the Invention
[0004] The technical problem to be solved by the present invention is: based on the above problem, the present invention provides a method for preparing Fe@Fe2O3 / GCN-NSs composite photocatalyst to improve the photocatalytic activity of g-C3N4.
[0005] One technical solution adopted by the present invention to solve its technical problem is: a method for preparing Fe@Fe2O3 / GCN-NSs composite photocatalyst, comprising the following steps:
[0006] (1) Preparation of GCN-NSs:
[0007] Melamine was placed in a tube furnace and calcined in three stages. First, it was heated to 550°C in air at a rate of 3°C / min and calcined for 2-4 hours. Then, it was heated to 550°C in air again at a rate of 3°C / min and calcined for 2-4 hours. Finally, it was calcined to 550°C in an Ar atmosphere at a rate of 3°C / min and calcined for 2-4 hours to obtain GCN-NSs.
[0008] (2) Preparation of Fe@Fe2O3 / GCN-NSs composite photocatalyst: GCN-NSs and FeSO4·7H2O were dissolved in deionized water, and the two solutions were mixed thoroughly and stirred for 24 h. Then, KBH4 aqueous solution was added dropwise. During the addition process, a large number of bubbles were rapidly generated, and the product floated in the solution. The solution was stirred continuously until the droplets were completely added. The solution was sealed with a plastic film and several small holes were punched to release the gas generated during the reaction. After standing for 4 h, the solution was washed with ethanol and deionized water and centrifuged several times. The solution was then dried in a vacuum oven at 60 °C for 24 h to obtain the Fe@Fe2O3 / GCN-NSs composite photocatalyst.
[0009] Furthermore, the mass of GCN-NSs in step (2) is 5-20% of FeSO4·7H2O.
[0010] Furthermore, the mass ratio of KBH4 to FeSO4·7H2O in step (2) is 2:1.
[0011] The application of the Fe@Fe2O3 / GCN-NSs composite photocatalyst prepared by the above method in the photocatalytic degradation of oxytetracycline is as follows:
[0012] The Fe@Fe2O3 / GCN-NSs composite photocatalyst was added to an aqueous solution of oxytetracycline, and a xenon lamp was used as the light source to carry out photocatalytic degradation of oxytetracycline.
[0013] Furthermore, the amount of Fe@Fe2O3 / GCN-NSs composite photocatalyst added is 10-30 mg / L.
[0014] Furthermore, the concentration of oxytetracycline in the aqueous solution is 10–30 mg / L.
[0015] Furthermore, the xenon lamp has a power of 500W.
[0016] The technical solution of the present invention achieves the following beneficial technical effects:
[0017] (1) This patent synthesizes a carbon nitride (GCN-NSs) with a thin sheet porous morphology through a three-step calcination method. Using melamine as raw material, after the first calcination polymerization to form a block carbon nitride with a multi-layer structure, the overflow force of nitrogen and ammonia generated in the second stage of calcination is used to increase the interlayer spacing, and the block carbon nitride becomes thinner and thinner, so that the gas generated in the third calcination can penetrate the layers to form pores, thereby finally obtaining carbon nitride (GCN-NSs) with a thin sheet porous morphology. It has a large specific surface area, charge transfer distance and abundant reaction sites, which is beneficial to the loading in the subsequent composite sample preparation process. Compared with ordinary block carbon nitride and sheet carbon nitride, its degradation effect is also improved to a certain extent.
[0018] (2) This invention uses Fe 2+ The Fe@Fe2O3 composite was generated by reduction and simultaneously directly supported on GCN-NSs, resulting in a Fe@Fe2O3 / GCN-NSs composite photocatalyst. This was achieved using Fe... 2+ Reduced to Fe 0 This makes the reduction process of zero-valent iron faster, simpler, and more efficient. The Fe@Fe2O3 and GCN-NSs composite process is concise, has low experimental costs, is environmentally friendly, and ensures a complete reaction. The preparation method has been improved and optimized compared to previous synthesis methods, enabling Fe... 0 The reduction is simpler and more complete, and the loading of composite samples is also simpler and faster. This catalyst can be applied to the field of visible light photocatalysis.
[0019] (3) The present invention can directly prepare photocatalysts with a defined morphology through a simple and easy preparation method, providing ideas and means for fields such as antibiotic degradation, photocatalytic degradation, and environmental protection, and has great promotional value. Attached image description:
[0020] Figure 1 These are X-ray diffraction patterns of GCN-NSs, Fe@Fe2O3, and 0.05-0.2Fe@Fe2O3 / GCN-NSs;
[0021] Figure 2 These are SEM images of GCN-NSs and Fe@Fe2O3, (a) is GCN-NSs, and (b) is Fe@Fe2O3;
[0022] Figure 3 This is a SEM image of 0.15Fe@Fe2O3 / GCN-NSs;
[0023] Figure 4 This is a TEM image of GCN-NSs;
[0024] Figure 5The graphs show the degradation effects of GCN-NSs, Fe@Fe2O3, and 0.05-0.2Fe@Fe2O3 / GCN-NSs on oxytetracycline (the shaded area from 0 to 30 min in the graphs represents the dark reaction).
[0025] Figure 6 This is a comparison chart of the removal rates of oxytetracycline by BCN, GCN, GCN-NSs, Fe2O3, Fe@Fe2O3, Fe@Fe2O3 / BCN, Fe@Fe2O3 / GCN, and 0.05-0.2Fe@Fe2O3 / GCN-NSs;
[0026] Figure 7 These are photoluminescence (PL) plots of GCN-NSs and 0.05-0.2Fe@Fe2O3 / GCN-NSs composite photocatalysts;
[0027] Figure 8 This is a circuit diagram of the photocatalytic experiment using 0.15Fe@Fe2O3 / GCN-NSs. Detailed Implementation
[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments. The drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.
[0029] Example 1
[0030] (1) Preparation of GCN-NSs: Melamine was placed in a tube furnace and calcined in air at a rate of 3℃ / min to 550℃ for 3h. After cooling to room temperature, it was calcined again in air at a rate of 3℃ / min to 550℃ for 2h. After cooling to room temperature, it was calcined for the third time in Ar atmosphere at a rate of 3℃ / min to 550℃ for 4h. After cooling to room temperature, orange-yellow powder of flake carbon nitride was finally obtained, which was denoted as GCN-NSs.
[0031] (2) Preparation of Fe@Fe2O3 / GCN-NSs: 0.04 g GCN-NSs and 0.75 g FeSO4·7H2O were dissolved in 40 mL and 10 mL of deionized water, respectively. The two solutions were mixed thoroughly and stirred for 24 h to form solution A. Then, 1.5 g KBH4 was added to 20 mL of deionized water to form solution B. Solution B was then added dropwise to solution A at room temperature. During the dropwise addition, a large number of bubbles were rapidly generated, and the product floated to the top of the solution. The solution was sealed with a plastic film and several small holes were punched to release the gas generated during the reaction. After standing for 4 h, the solution was washed with ethanol and deionized water and centrifuged several times. The solution was then dried in a vacuum oven at 60 °C for 24 h to obtain the Fe@Fe2O3 / GCN-NSs composite photocatalyst, labeled as 0.05Fe@Fe2O3 / GCN-NSs.
[0032] Example 2
[0033] The difference between Example 2 and Example 1 is that the amount of GCN-NSs added in step (2) is 0.15g, and the Fe@Fe2O3 / GCN-NSs composite photocatalyst is labeled as 0.2Fe@Fe2O3 / GCN-NSs.
[0034] Example 3
[0035] The difference between Example 3 and Example 1 is that the amount of GCN-NSs added in step (2) is 0.08g, and the Fe@Fe2O3 / GCN-NSs composite photocatalyst is labeled as 0.1Fe@Fe2O3 / GCN-NSs.
[0036] Example 4
[0037] The difference between Example 4 and Example 1 is that the amount of GCN-NSs added in step (2) is 0.11g, and the Fe@Fe2O3 / GCN-NSs composite photocatalyst is labeled as 0.15Fe@Fe2O3 / GCN-NSs.
[0038] Comparative Example 1
[0039] Preparation of BCN: Melamine was placed in a tube furnace and calcined in air at a rate of 3℃ / min to 550℃ for 3 hours. After cooling to room temperature, blocky carbon nitride was obtained, denoted as BCN.
[0040] Comparative Example 2
[0041] Preparation of GCN: Melamine was placed in a tube furnace and calcined in air at a rate of 3℃ / min to 550℃ for 3 hours. After cooling to room temperature, it was calcined again in air at a rate of 3℃ / min to 550℃ for 2 hours. After cooling to room temperature, flake carbon nitride was obtained, denoted as GCN.
[0042] Comparative Example 3
[0043] Preparation of GCN-NSs: Melamine was placed in a tube furnace and calcined in air at a rate of 3℃ / min to 550℃ for 3 hours. After cooling to room temperature, it was calcined again in air at a rate of 3℃ / min to 550℃ for 2 hours. After cooling to room temperature, it was calcined for the third time in an Ar atmosphere at a rate of 3℃ / min to 550℃ for 4 hours. After cooling to room temperature, orange-yellow powder of flake carbon nitride was finally obtained, which was denoted as GCN-NSs.
[0044] Comparative Example 4
[0045] Preparation of Fe2O3: 0.75 g of FeSO4·7H2O was dissolved in 10 mL of deionized water, and 0.3 g of NaOH was added at room temperature to generate a reddish-brown Fe(OH)3 colloidal solution. The reaction was heated at 80 °C for 2 h, and FeSO4 reacted with O2 to generate red Fe2O3.
[0046] Comparative Example 5
[0047] Preparation of Fe@Fe2O3: 0.75 g of FeSO4·7H2O was dissolved in 10 mL of deionized water and labeled as solution A. 1.5 g of KBH4 was dissolved in 20 mL of deionized water and labeled as solution B. Solution B was then added dropwise to solution A at room temperature. During the addition process, a large number of bubbles were rapidly generated, and the product floated to the surface. The solution was sealed with a plastic film, with several small holes punched to allow the gases generated during the reaction to escape. After standing for 4 hours, the product was washed several times with ethanol and deionized water, centrifuged, and dried in a vacuum oven at 60 °C for 24 hours. The final product was labeled as Fe@Fe2O3.
[0048] Comparative Example 6
[0049] Preparation of Fe@Fe2O3 / BCN: 0.04 g BCN and 0.75 g FeSO4·7H2O were dissolved in 40 mL and 10 mL of deionized water, respectively. The two solutions were mixed thoroughly and stirred for 24 h to form solution A. Then, 1.5 g KBH4 was added to 20 mL of deionized water to form solution B. Solution B was then added dropwise to solution A at room temperature. During the dropwise addition, a large number of bubbles were rapidly generated, and the product floated to the top of the solution. The solution was sealed with a plastic film and several small holes were punched to release the gas generated during the reaction. After standing for 4 h, the product was washed several times with ethanol and deionized water and centrifuged. It was then dried in a vacuum oven at 60 °C for 24 h. The final product was the Fe@Fe2O3 / BCN composite photocatalyst, labeled as Fe@Fe2O3 / BCN.
[0050] Comparative Example 7
[0051] Preparation of Fe@Fe2O3 / GCN: 0.04 g GCN and 0.75 g FeSO4·7H2O were dissolved in 40 mL and 10 mL of deionized water, respectively. The two solutions were mixed thoroughly and stirred for 24 h to form solution A. Then, 1.5 g KBH4 was added to 20 mL of deionized water to form solution B. Solution B was then added dropwise to solution A at room temperature. During the dropwise addition, a large number of bubbles were rapidly generated, and the product floated to the top of the solution. The solution was sealed with a plastic film and several small holes were punched to release the gas generated during the reaction. After standing for 4 h, the product was washed several times with ethanol and deionized water and centrifuged. It was then dried in a vacuum oven at 60 °C for 24 h. The final product was the Fe@Fe2O3 / GCN composite photocatalyst, labeled as Fe@Fe2O3 / GCN.
[0052] The crystal structures of the photocatalysts prepared in Examples 1-4 were analyzed using a Rigaku D / max2500GC spinning X-ray diffractometer (Japan). The X-ray diffraction patterns are shown below. Figure 1 As shown, GCN-NSs exhibits two typical (100) and (002) diffraction peaks, centered at 13.1° and 27.8°, respectively; Fe 0 The peak positions of Fe2O3 and Fe@Fe2O3 / GCN-NSs composite catalysts are consistent with those of the pure sample, which fully demonstrates the successful synthesis of the three-phase mixture.
[0053] Figure 2 a is a scan image of GCN-NSs. After morphology regulation, carbon nitride is more fluffy, exhibits a sheet-like structure, increases specific surface area, and increases the number of active sites. Figure 2 b is a scanning electron microscope image of the Fe@Fe2O3 copolymer, showing a polymeric spherical chain structure; Figure 3 The image shows a scanning electron microscope (SEM) image of the Fe@Fe2O3 / GCN-NSs composite catalyst, confirming that the Fe@Fe2O3 copolymer was successfully loaded onto GCN-NSs. Figure 4 This is a transmission image of GCN-NSs, showing the porous morphology of its flakes.
[0054] The catalysts prepared in Examples 1-4 and Comparative Examples 1-7 were applied to the photocatalytic degradation of oxytetracycline. The specific steps were as follows: 10 mg of the photocatalyst was added to 50 mL of a 30 mg / L oxytetracycline aqueous solution. A 500 W xenon lamp was used as the light source to carry out the photocatalytic degradation reaction. The dark reaction lasted for 30 min. After illumination, 3 mL of the suspension was aspirated every 30 min using a 3 mL pipette, and this was repeated 5 times. The suspension was then analyzed using a UV-Vis absorption spectrometer. Figure 5 It can be seen that the degradation rate of oxytetracycline by the Fe@Fe2O3 / GCN-NSs composite photocatalyst can reach about 90% within 150 min, indicating that the prepared Fe@Fe2O3 / GCN-NSs composite photocatalyst has high photocatalytic activity.
[0055] Figure 6This is a bar chart comparing the OTC removal rates of BCN, GCN, GCN-NSs, Fe2O3, Fe@Fe2O3, Fe@Fe2O3 / BCN, Fe@Fe2O3 / GCN, and 0.05-0.2Fe@Fe2O3 / GCN-NSs. The chart shows that in the three-step calcination method, BCN obtained from only one calcination and GCN obtained from two calcinations have OTC removal rates of 33% and 40%, respectively. However, GCN-NSs obtained from three calcinations has an OTC removal rate of approximately 58%. This indicates that the removal rate of GCN-NSs obtained through the three-step calcination method is significantly higher than that of carbon nitride obtained from the first two stages. This is because the carbon nitride obtained after three calcinations is more porous, has a larger specific surface area, and is more exposed. The active sites are more numerous; the composite samples Fe@Fe2O3 / BCN and Fe@Fe2O3 / GCN, which were formed by combining BCN and GCN with Fe@Fe2O3 respectively, showed OTC removal rates of 50% and 52% respectively, which were lower than those of the composite sample 0.05-0.2Fe@Fe2O3 / GCN-NSs formed by combining GCN-NSs with Fe@Fe2O3 after three calcinations; and the removal rate of 0.05-0.2Fe@Fe2O3 / GCN-NSs was significantly improved compared to Fe2O3 and Fe@Fe2O3, with 0.15Fe@Fe2O3 / GCN-NSs showing the highest removal rate.
[0056] Figure 7 The spectrum of GCN-NSs and 0.05-0.2Fe@Fe2O3 / GCN-NSs composite photocatalyst at an excitation wavelength of 350 nm is obtained from... Figure 7 It was found that the addition of Fe@Fe2O3 significantly reduced the photogenerated carrier recombination rate of the Fe@Fe2O3 / plate-like carbon nitride GCN-NSs composite photocatalyst. Among them, the 0.15Fe@Fe2O3 / GCN-NSs composite photocatalyst exhibited the lowest emission peak intensity, indicating that it possesses higher separation and transfer efficiency. This demonstrates that the carrier recombination rate of the Fe@Fe2O3 / GCN-NSs composite photocatalyst was effectively suppressed, and its photocatalytic activity was enhanced. These results confirm that the combination of Fe@Fe2O3 and GCN-NSs can improve the charge separation performance of Fe@Fe2O3 / GCN-NSs.
[0057] To verify the stability of the Fe@Fe2O3 / GCN-NSs composite photocatalyst prepared in this invention, photocatalytic cycling tests were conducted on the Fe@Fe2O3 / GCN-NSs composite photocatalysts prepared in Examples 1-4. The experimental results are as follows: Figure 8As shown, the Fe@Fe2O3 / GCN-NSs composite photocatalyst exhibits good stability.
[0058] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. Application of Fe@Fe2O3 / GCN-NSs composite photocatalyst in photocatalytic degradation of terramycin, characterized in that, The preparation method of the Fe@Fe2O3 / GCN-NSs composite photocatalyst comprises the following steps: (1) Put melamine into a tubular furnace, calcine for 2-4 h under an air atmosphere, cool to room temperature, then calcine again for 2-4 h under an air atmosphere, cool to room temperature, finally calcine for 2-4 h under an Ar atmosphere, cool to room temperature, and obtain orange-yellow powder GCN-NSs; (2) Dissolve the GCN-NSs and FeSO4·7H2O in deionized water respectively, mix the two solutions thoroughly, stir for 24 h, then drop in KBH4 aqueous solution, seal with plastic film and punch several small holes to discharge the gas generated in the reaction process, stand for 4 h, then centrifuge, wash and dry to obtain the Fe@Fe2O3 / GCN-NSs composite photocatalyst.
2. The application of the Fe@Fe2O3 / GCN-NSs composite photocatalyst in photocatalytic degradation of terramycin according to claim 1, characterized in that, In step (1), the calcination temperature is 550 ℃, and the heating rate is 3 ℃ / min.
3. The application of the Fe@Fe2O3 / GCN-NSs composite photocatalyst in photocatalytic degradation of terramycin according to claim 1, characterized in that, In step (2), the mass of the GCN-NSs is 5-20 % of that of the FeSO4·7H2O.
4. The application of the Fe@Fe2O3 / GCN-NSs composite photocatalyst in photocatalytic degradation of terramycin according to claim 1, characterized in that, In step (2), the mass ratio of the KBH4 to the FeSO4·7H2O is 2:
1.
5. The use according to claim 1, characterized in that, The specific steps are as follows: Add the Fe@Fe2O3 / GCN-NSs composite photocatalyst into an oxytetracycline aqueous solution, use a xenon lamp as a light source, and perform photocatalytic degradation of the oxytetracycline.
6. Use according to claim 5, characterized in that, The addition amount of the Fe@Fe2O3 / GCN-NSs composite photocatalyst is 10-30 mg / L; The concentration of the oxytetracycline in the oxytetracycline aqueous solution is 10-30 mg / L.
7. Use according to claim 5, characterized in that, The power of the xenon lamp is 500 W.