Sandwich structure different Fe2O3 composite material and preparation method and use thereof
By constructing a sandwich-structured Fe2O3 composite material, the problem of easy recombination of photogenerated carriers was solved, and a highly efficient photocatalytic degradation effect on wastewater was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-25
- Publication Date
- 2026-03-24
AI Technical Summary
The existing Fe2O3 photocatalytic materials suffer from problems such as easy recombination of photogenerated carriers and low transport efficiency, which limits their application in the photocatalytic degradation of wastewater.
A sandwich-structured Fe2O3 composite material was constructed by coating γ-Fe2O3 onto the surface of α-Fe2O3 to form two heterogeneous junctions, thereby improving the separation and transfer efficiency of photogenerated electrons and holes.
It significantly enhances the reactivity of photocatalysts, improves visible light response performance, reduces costs, and avoids secondary pollution.
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Figure CN117463336B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of composite catalyst preparation, and in particular to a sandwich-structured Fe2O3 composite material, its preparation method, and its applications. Background Technology
[0002] Due to the rapid development of science and technology and the economy, many industries discharge large amounts of wastewater every day, especially the chemical, dye, pharmaceutical, and agricultural industries. The wastewater discharged by these industries is not only large in volume but also complex in composition and has a low natural degradation rate, posing a huge risk to the ecological environment and human life. Solving the water pollution problem is urgent.
[0003] Among the various water pollution purification methods adopted by researchers both domestically and internationally, chemical and adsorption methods are prone to secondary pollution, while biological treatment has an excessively long implementation cycle. Photocatalytic degradation, however, has attracted widespread attention due to its high efficiency, significant effects, and economic and environmental benefits. Compared to the typical photocatalytic material TiO2, Fe2O3 has a narrower band gap, meaning it possesses superior visible light response performance. Furthermore, hematite (Fe2O3) is abundant, inexpensive, and readily available, offering environmental advantages and demonstrating significant application potential in the field of photocatalysis. The limiting factor for its performance is the tendency for photogenerated carriers to recombine and their low transport efficiency. To improve the performance of photocatalytic materials, researchers both domestically and internationally have proposed many methods. Among these, constructing heterojunctions and heterophase junctions is an effective strategy for promoting the separation of photogenerated charges. A "heterojunction" refers to the interface between different substances, while a "heterophase junction" refers to the interface between different crystal phases of the same substance. Heterophase junctions, in particular, have a greater advantage in the separation and transfer efficiency of photogenerated electrons and holes. Constructing heterojunctions between different crystalline phases of Fe2O3 can effectively improve its defects of easy recombination of photogenerated carriers and low transport efficiency. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a sandwich-structured Fe2O3 composite material, its preparation method, and its applications. The prepared sandwich-structured Fe2O3 composite material has two contact interfaces with different crystal phases, forming two heterogeneous junctions. When used as a photocatalyst for the photocatalytic degradation of wastewater, it significantly enhances the photocatalyst's reactivity.
[0005] To achieve the above objectives, the present invention is implemented according to the following technical solution:
[0006] The first objective of this invention is to provide a method for preparing a sandwich-structured Fe2O3 composite material, comprising the following steps:
[0007] S1. Dissolve the iron salt in 20 times its weight of deionized water and stir until completely dissolved to obtain an iron salt solution.
[0008] S2. Add KH2PO4 to the iron salt solution and stir until completely dissolved to obtain a mixed solution, wherein the weight ratio of potassium dihydrogen phosphate to iron salt is 1:25-100.
[0009] S3. Place the mixed solution in an Erlenmeyer flask and carry out a hydrothermal reaction, wherein the hydrothermal reaction temperature is 100-250℃ and the reaction time is 2-72h;
[0010] S4. Centrifuge the product after hydrothermal reaction, wash with deionized water, and dry to obtain α-phase Fe2O3, i.e., α-Fe2O3.
[0011] S5. Grind α-Fe2O3 into a uniform powder, add polyethylene glycol at a mass ratio of ferric oxide to polyethylene glycol of 1:0.5-8, place it in a crucible and place it in a muffle furnace for calcination. After cooling, take the sample out of the crucible and grind it again in a mortar to obtain α-Fe2O3 with γ phase Fe2O3, i.e. γ-Fe2O3 coating.
[0012] S6. Place the α-Fe2O3 coated with γ-Fe2O3 into a crucible and calcine it in a muffle furnace. After cooling, remove the sample from the crucible to obtain the sandwich-structured Fe2O3 composite material.
[0013] Furthermore, the iron salt is ferric chloride or ferric sulfate.
[0014] Preferably, the drying temperature in step S4 is 55℃~65℃.
[0015] Preferably, the calcination temperature in step S5 is 200–800°C, and the time is 10–180 min.
[0016] Preferably, the calcination temperature in step S6 is 100-200°C and the time is 10-180 minutes.
[0017] The second objective of this invention is to provide a sandwich-structured Fe2O3 composite material prepared by the above method, wherein the sandwich-structured Fe2O3 composite material is composed of layers of α-Fe2O3, γ-Fe2O3, and α-Fe2O3 from the inside out.
[0018] A third objective of this invention is to provide a use of a sandwich-structured Fe2O3 composite material, which is used as a photocatalyst for the photocatalytic degradation of wastewater.
[0019] Compared with the prior art, the present invention has the following beneficial effects:
[0020] 1. From the perspective of the preparation process, the preparation process of the sandwich-structured Fe2O3 composite material of the present invention is simple and easy to operate, which is beneficial to expanding the application range of α-Fe2O3. This sandwich-structured Fe2O3 composite material can be used as a photocatalyst for the photocatalytic degradation of wastewater.
[0021] 2. From a cost perspective, compared to other photocatalytic materials, the sandwich-structured Fe2O3 composite material is cheaper, and the iron oxide itself does not cause secondary pollution, further reducing the cost of pollution treatment.
[0022] 3. From the perspective of reactivity, the sandwich-structured Fe2O3 composite material prepared by this invention has a narrower band gap, which gives it higher visible light response performance. The construction of the heterojunction improves the transfer efficiency of photogenerated electrons and holes. Moreover, its sandwich-structured structure constructs two contact interfaces of α and γ phases, which not only enhances the absorption of visible light, but also further improves the transfer efficiency of photogenerated electrons and holes. Attached Figure Description
[0023] Figure 1 The synthesis process of the sandwich-structured Fe2O3 composite material of the present invention is described.
[0024] Figure 2 The diagram shows the phase analysis of the α-Fe2O3, γ-phase Fe2O3-coated α-Fe2O3, and sandwich-structured Fe2O3 composite materials prepared in steps one through three of Example 1.
[0025] Figure 3 The diagram shows the phase composition ratios of the α-Fe2O3, γ-phase Fe2O3-coated α-Fe2O3, and sandwich-structured Fe2O3 composite materials prepared in steps one through three of Example 1.
[0026] Figure 4 The images show the morphology of the α-Fe2O3, γ-phase Fe2O3-coated α-Fe2O3, and sandwich-structured Fe2O3 composite materials prepared in steps one through three of Example 1.
[0027] Figure 5 The image shows the morphology of the sandwich-structured Fe2O3 composite material prepared in Example 2.
[0028] Figure 6 The degradation diagrams of Rhodamine B by the sandwich-structured Fe2O3 composite materials prepared in Examples 1-4, and α-Fe2O3 and γ-phase Fe2O3-coated α-Fe2O3 as photocatalysts. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.
[0030] Example 1
[0031] Step 1: Dissolve 10.76g of FeCl3·6H2O in 200mL of deionized water and stir until completely dissolved. Then add 0.054g of KH2PO4 to the ferric chloride solution and stir until completely dissolved. Seal the pale yellow mixture and place it in a hydrothermal oven at 100℃ for 72 hours. After the hydrothermal reaction, allow the mixture to cool, centrifuge, and wash three times with deionized water. Place the resulting reddish-brown product in a 60℃ oven and dry for 12 hours. Finally, remove the dried sample and grind it into powder in a mortar to obtain spindle-shaped α-Fe2O3.
[0032] Step 2: Weigh 0.1g of the α-Fe2O3 obtained in Step 1, and mix 0.1g of PEG-1000 with the α-Fe2O3 evenly. Place the mixture in a crucible and calcine it in a muffle furnace at 300℃. After calcining for 1 hour, stop the calcination and allow it to cool. Remove the sample from the crucible and grind it again in a mortar to obtain α-Fe2O3 coated with γ-phase Fe2O3.
[0033] Step 3: Weigh 0.1g of the sample obtained in Step 2, place it in a crucible, and calcine it in a muffle furnace at 120℃ for 30 minutes. After cooling, remove the sample from the crucible to obtain the sandwich-structured Fe2O3 composite material. (Specific details are as follows...) Figure 1 As shown, the sandwich-structured Fe2O3 composite material is composed of layers of α-Fe2O3, γ-Fe2O3, and α-Fe2O3 from the inside out.
[0034] The phase analysis diagrams of the α-Fe2O3, γ-Fe2O3-coated α-Fe2O3, and sandwich-structured Fe2O3 composite materials prepared in steps one through three of this embodiment are shown below. Figure 2 As shown, by Figure 2 As can be seen from the XRD characterization, pure α-Fe2O3 and α-Fe2O3 coated with γ-Fe2O3 were prepared through the above steps. Due to different preparation conditions, the peak intensities of γ-Fe2O3 and α-Fe2O3 in the sample changed, indicating that the ratio of γ-Fe2O3 to α-Fe2O3 changed. The further increase in the ratio of α-Fe2O3 indicates that α-Fe2O3 appeared on the outer layer of γ-Fe2O3, that is, a sandwich-like structure was produced.
[0035] The phase composition ratio diagrams of the α-Fe2O3, γ-phase Fe2O3-coated α-Fe2O3, and sandwich-structured Fe2O3 composite materials prepared in steps one through three of this embodiment are shown below. Figure 3 As shown, by Figure 3 It can be seen that, based on XRD, the content ratio of γ-Fe2O3 and α-Fe2O3 can be calculated and the content ratio of γ-Fe2O3 and α-Fe2O3 can be controlled by different preparation processes.
[0036] In this embodiment, the morphology images of the α-Fe2O3, γ-phase Fe2O3-coated α-Fe2O3, and sandwich-structured Fe2O3 composite materials prepared in steps one through three are shown below. Figure 4 As shown, by Figure 4 It can be seen that the morphology of the sample did not change through SEM characterization. Although the preparation process can adjust the phase ratio of the sample, it has almost no effect on the morphology of the sample.
[0037] Example 2
[0038] Step 1: Dissolve 10.76g of ferric sulfate in 200mL of deionized water and stir until completely dissolved. Then add 0.054g of KH₂PO₄ to the ferric chloride solution and stir until completely dissolved. Seal the pale yellow mixture and place it in a hydrothermal oven at 100℃ for 72 hours. After the hydrothermal reaction, allow the mixture to cool, centrifuge, and wash three times with deionized water. Place the resulting reddish-brown product in a 60℃ oven and dry for 12 hours. Finally, remove the dried sample and grind it into powder in a mortar to obtain spindle-shaped α-Fe₂O₃.
[0039] Step 2: Weigh 0.1g of the α-Fe2O3 obtained in Step 1, and mix 0.1g of PEG-1000 with the α-Fe2O3 evenly. Place the mixture in a crucible and calcine it in a muffle furnace at 300℃. After calcining for 1 hour, stop the calcination and allow it to cool. Remove the sample from the crucible and grind it again in a mortar to obtain α-Fe2O3 coated with γ-phase Fe2O3.
[0040] Step 3: Weigh 0.1g of the sample obtained in Step 2, place it in a crucible, and calcine it in a muffle furnace at 120℃ for 30 minutes. After cooling, remove the sample from the crucible to obtain the sandwich-structured Fe2O3 composite material. Its morphology is shown in the figure below. Figure 5 As shown, by Figure 5 It can be seen that this embodiment also yields Fe2O3 with the same shape and structure as that in Embodiment 1, which is a sandwich structure with similarities and differences.
[0041] Example 3
[0042] Step 1: Dissolve 10.76g of FeCl3·6H2O in 200mL of deionized water and stir until completely dissolved. Then add 0.054g of KH2PO4 to the ferric chloride solution and stir until completely dissolved. Seal the pale yellow mixture and place it in a hydrothermal oven at 100℃ for 72 hours. After the hydrothermal reaction, allow the mixture to cool, centrifuge, and wash three times with deionized water. Place the resulting reddish-brown product in a 60℃ oven and dry for 12 hours. Finally, remove the dried sample and grind it into powder in a mortar to obtain spindle-shaped α-Fe2O3.
[0043] Step 2: Weigh 0.1g of the α-Fe2O3 obtained in Step 1, and then mix 0.4g of PEG-1000 with the α-Fe2O3 evenly. Place the mixture in a crucible and calcine it in a muffle furnace at 300℃. After calcining for 1 hour, stop the calcination and allow it to cool. Then, take the sample out of the crucible and grind it again in a mortar to obtain α-Fe2O3 coated with γ-phase Fe2O3.
[0044] Step 3: Weigh 0.1g of the sample obtained in Step 2, place it in a crucible, and calcine it in a muffle furnace at 120℃ for 30 minutes. After cooling, remove the sample from the crucible to obtain the sandwich-structured Fe2O3 composite material.
[0045] Example 4
[0046] Step 1: Dissolve 10.76g of FeCl3·6H2O in 200mL of deionized water and stir until completely dissolved. Then add 0.054g of KH2PO4 to the ferric chloride solution and stir until completely dissolved. Seal the pale yellow mixture and place it in a hydrothermal oven at 100℃ for 72 hours. After the hydrothermal reaction, allow the mixture to cool, centrifuge, and wash three times with deionized water. Place the resulting reddish-brown product in a 60℃ oven and dry for 12 hours. Finally, remove the dried sample and grind it into powder in a mortar to obtain spindle-shaped α-Fe2O3.
[0047] Step 2: Weigh 0.1g of the α-Fe2O3 obtained in Step 1, and mix 0.1g of PEG-1000 with the α-Fe2O3 evenly. Place the mixture in a crucible and calcine it in a muffle furnace at 500℃. After calcineing for 1 hour, stop the calcine and allow it to cool. Remove the sample from the crucible and grind it again in a mortar to obtain α-Fe2O3 coated with γ-phase Fe2O3.
[0048] Step 3: Weigh 0.1g of the sample obtained in Step 2, place it in a crucible, and calcine it in a muffle furnace at 120℃ for 30 minutes. After cooling, remove the sample from the crucible to obtain the sandwich-structured Fe2O3 composite material.
[0049] Example 5
[0050] Using Rhodamine B as the target pollutant, the sandwich-structured Fe2O3 composite materials prepared in Examples 1-4 were used as photocatalysts. The α-Fe2O3 and γ-phase Fe2O3-coated α-Fe2O3 prepared in Examples 1 and 2 were used as controls for photocatalytic performance testing. 60 mL of 10 mg / L Rhodamine B was placed in a reactor, and 0.05 g of α-Fe2O3, γ-phase Fe2O3-coated α-Fe2O3, or sandwich-structured Fe2O3 composite materials were added. The solution was continuously stirred to form a suspension. The reactor was placed below the light outlet of a mercury lamp, maintaining a constant distance between the Rhodamine B surface and the lamp outlet. Before turning on the lamp, the solution was stirred for 10 min in darkness to reach adsorption equilibrium. After illumination, the same volume of the supernatant was taken every 10 min, centrifuged, and the absorbance at the maximum absorption wavelength was measured using a UV spectrophotometer to determine the photocatalytic degradation rate of Rhodamine B.
[0051] Photodegradation rate analysis method: D=(A0-A) / A0×100%;
[0052] Where D is the photodegradation rate, A0 is the theoretical absorbance of the pollutant at the maximum absorption wavelength, and A is the absorbance of the pollutant when the illumination time is t.
[0053] Test results are as follows Figure 6 As shown, by Figure 6 It can be seen that α-Fe2O3 and γ-Fe2O3 coated α-Fe2O3 can also play a certain role in the degradation of Rhodamine B, with γ-Fe2O3 coated α-Fe2O3 showing better degradation effect than α-Fe2O3. However, the degradation effect of both α-Fe2O3 and γ-Fe2O3 coated α-Fe2O3 is significantly lower than that of the sandwich-structured Fe2O3 composite material. The samples in Examples 1-4 all played a good role in the degradation of Rhodamine B, with Example 3 showing the most outstanding degradation effect.
[0054] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.
Claims
1. A method for preparing a sandwich-structured Fe2O3 composite material, characterized in that, Includes the following steps: S1. Dissolve the iron salt in 20 times its weight of deionized water and stir until completely dissolved to obtain an iron salt solution. S2. Add KH2PO4 to the iron salt solution and stir until completely dissolved to obtain a mixed solution, wherein the weight ratio of potassium dihydrogen phosphate to iron salt is 1:25~100. S3. Place the mixed solution in an Erlenmeyer flask and carry out a hydrothermal reaction, wherein the hydrothermal reaction temperature is 100~250℃ and the reaction time is 2~72h; S4. Centrifuge the product after hydrothermal reaction, wash with deionized water, and dry to obtain α-phase Fe2O3, i.e., α-Fe2O3. S5. Grind α-Fe2O3 into a uniform powder, add polyethylene glycol at a mass ratio of ferric oxide to polyethylene glycol of 1:0.5~8, place it in a crucible and place it in a muffle furnace for calcination at a temperature of 200~800℃ for 10min~180min. After cooling, take the sample out of the crucible and grind it again in a mortar to obtain α-Fe2O3 with γ phase Fe2O3, i.e. γ-Fe2O3 coating. S6. Place the γ-Fe2O3-coated α-Fe2O3 into a crucible and calcine it in a muffle furnace. After cooling, remove the sample from the crucible to obtain the sandwich-structured Fe2O3 composite material. The sandwich-structured Fe2O3 composite material is composed of layers of α-Fe2O3, γ-Fe2O3, and α-Fe2O3 from the inside out.
2. The method for preparing the sandwich-structured Fe2O3 composite material according to claim 1, characterized in that: The iron salt is ferric chloride or ferric sulfate.
3. The method for preparing the sandwich-structured Fe2O3 composite material according to claim 1, characterized in that, The drying temperature in step S4 is 55℃~65℃.
4. The method for preparing the sandwich-structured Fe2O3 composite material according to claim 1, characterized in that, The calcination temperature in step S6 is 100~200℃, and the time is 10min~180min.
5. A sandwich-structured Fe2O3 composite material prepared by the method according to any one of claims 1-4.
6. The use of the sandwich-structured Fe2O3 composite material as described in claim 5, characterized in that: The sandwich-structured Fe2O3 composite material is used as a photocatalyst for the photocatalytic degradation of wastewater.
Citation Information
Patent Citations
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