A manganese ferrite / bismuth tungstate heterojunction photocatalyst and a preparation method and application thereof
By constructing a manganese ferrite/bismuth tungstate heterojunction photocatalyst, the problem of low carrier separation efficiency in photocatalysts was solved, and the efficient reduction of carbon dioxide to carbon monoxide was achieved, demonstrating good photocatalytic activity and large-scale production potential.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LIAONING UNIVERSITY
- Filing Date
- 2025-04-30
- Publication Date
- 2026-08-04
AI Technical Summary
Existing photocatalysts are unable to effectively separate photogenerated electron and hole pairs, resulting in insufficient photocatalytic activity and difficulty in efficiently converting carbon dioxide into hydrocarbon solar fuels.
A heterojunction photocatalyst was constructed using manganese ferrite and bismuth tungstate. It was prepared by alkaline etching to form a heterojunction structure to improve carrier separation efficiency and to catalyze the reduction of carbon dioxide to carbon monoxide under visible light.
This method improves the carrier separation efficiency and photocatalytic activity of the photocatalyst, achieving efficient carbon dioxide reduction. Furthermore, the preparation method is simple, low-cost, and suitable for large-scale production.
Smart Images
Figure CN120420995B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to a manganese ferrite / bismuth tungstate heterojunction photocatalyst, its preparation method, and its application. Background Technology
[0002] Photocatalytic carbon dioxide reduction utilizes inexhaustible solar energy, directly converting carbon dioxide gas into hydrocarbon solar fuels, making it a feasible method to simultaneously address the energy crisis and environmental pollution. Therefore, bismuth tungstate (Bi₂WO₆), a narrow-bandgap semiconductor and a typical Aurivillius phase oxide, has been extensively studied in the field of photocatalysis. It is composed of [Bi₂O₂]. 2+ Layers and [WO4] 2- The photocatalysts are composed of alternating layers, with oxygen atoms shared between each layer. This staggered, layered structure helps to facilitate the separation of photogenerated carriers. However, under current conditions, single-component photocatalysts struggle to effectively separate photogenerated electron and hole pairs.
[0003] Therefore, manganese ferrite, due to its narrow band gap, excellent photochemical stability, and environmental friendliness, has a wide range of photocatalytic applications and can be combined with Bi₂WO₆ to construct heterostructures. Manganese ferrite is also a transition metal oxide; introducing active metal sites can enhance the adsorption of carbon dioxide by Bi₂WO₆. Constructing a manganese ferrite / bismuth tungstate heterojunction can improve carrier separation efficiency, thereby enhancing the photocatalytic activity of Bi₂WO₆. Summary of the Invention
[0004] This invention addresses the shortcomings of existing technologies by providing a method for preparing a manganese ferrite / bismuth tungstate photocatalyst and its application in the photocatalytic reduction of carbon dioxide. This method is simple, convenient, low-cost, and operates under mild conditions, which is conducive to large-scale production. The obtained manganese ferrite / bismuth tungstate photocatalyst exhibits excellent photocatalytic reduction activity for carbon dioxide.
[0005] The technical solution adopted in this invention is as follows:
[0006] A manganese ferrite / bismuth tungstate heterojunction photocatalyst, wherein the molar ratio of the total molar mass of manganese ferrite to the heterojunction photocatalyst is 1:10, 2:10, 3:10 or 5:10.
[0007] The preparation method of the above-mentioned manganese ferrite / bismuth tungstate heterojunction photocatalyst includes the following steps:
[0008] 1) Sodium tungstate dihydrate, bismuth nitrate pentahydrate, and hexadecyltrimethylammonium bromide were dissolved in deionized water and subjected to a hydrothermal reaction to obtain bismuth tungstate;
[0009] 2) Dissolve ferric chloride hexahydrate and manganese chloride tetrahydrate in water, then add sodium hydroxide solution, and react hydrothermally to obtain manganese ferrate;
[0010] 3) Dissolve bismuth tungstate and manganese ferrite in sodium hydroxide solution, then stir and dry to obtain manganese ferrite / bismuth tungstate heterojunction photocatalyst.
[0011] Furthermore, in the above preparation method, in step 1), sodium tungstate dihydrate: bismuth nitrate pentahydrate = 0.1-1g: 0.5-1.5g.
[0012] Furthermore, in the above preparation method, in step 1), the amount of hexadecyltrimethylammonium bromide added is 0.05-1g.
[0013] Furthermore, in the above preparation method, in step 1), the hydrothermal reaction temperature is 80-150℃ and the hydrothermal reaction time is 18-36h.
[0014] Furthermore, in the above preparation method, in step 2), the ratio of ferric chloride hexahydrate: manganese chloride tetrahydrate: sodium hydroxide is 1-4 g: 0.5-1.5 g: 0.0008-0.001 mol.
[0015] Furthermore, in the above preparation method, in step 2), the hydrothermal reaction temperature is 160-200℃ and the hydrothermal reaction time is 6-18h.
[0016] Furthermore, in the above preparation method, in step 3), the stirring time is 1-5 hours.
[0017] The above-mentioned manganese ferrite / bismuth tungstate heterojunction photocatalyst is used in the photocatalytic reduction of carbon dioxide.
[0018] Furthermore, the above application is carried out in the following way: under visible light irradiation, the manganese ferrite / bismuth tungstate heterojunction photocatalyst is placed in a closed space filled with carbon dioxide gas, and the carbon dioxide gas is reduced to carbon monoxide gas.
[0019] The beneficial effects of this invention are as follows:
[0020] 1. This invention utilizes an alkaline etching method to prepare a manganese ferrite / bismuth tungstate heterojunction photocatalyst. The heterojunction structure of this material can improve the carrier separation efficiency, thereby achieving the purpose of improving photocatalytic activity.
[0021] 2. The present invention utilizes a manganese ferrite / bismuth tungstate heterojunction photocatalyst constructed by alkaline etching. The bismuth tungstate nanoflowers have a large specific surface area, which can provide more reactive sites in the photocatalytic reaction. The introduction of manganese ferrite can form a heterostructure with bismuth tungstate, which is beneficial to further improve the carrier separation efficiency.
[0022] 3. The manganese ferrite / bismuth tungstate heterojunction photocatalyst prepared by this invention has stronger photocatalytic reduction ability, participates in catalytic reactions, and has good photocatalytic reduction performance of carbon dioxide. Moreover, the method is simple, convenient, low-cost, mild, and conducive to large-scale production. Attached Figure Description
[0023] Figure 1 These are the XRD patterns of O-BWO, MFO, 10MFO / O-BWO, 20MFO / O-BWO, 30MFO / O-BWO and 50MFO / O-BWO.
[0024] Figure 2 This is a SEM image of MFO.
[0025] Figure 3 This is a SEM image of O-BWO.
[0026] Figure 4 SEM image of 20MFO / O-BWO.
[0027] Figure 5 Comparison of photocatalytic reduction of carbon dioxide reactions for O-BWO, MFO, 10MFO / O-BWO, 20MFO / O-BWO, 30MFO / O-BWO and 50MFO / O-BWO.
[0028] Figure 6 Comparison of photocatalytic carbon dioxide reduction activities of O-BWO, MFO, 10MFO / O-BWO, 20MFO / O-BWO, 30MFO / O-BWO and 50MFO / O-BWO. Detailed Implementation
[0029] Example 1: A manganese ferrite / bismuth tungstate photocatalyst (molar ratio of manganese ferrite to the total molar mass of the composite material is 1:10)
[0030] 1) Dissolve 0.33 g of sodium tungstate dihydrate, 0.97 g of bismuth nitrate pentahydrate, and 0.05 g of hexadecyltrimethylammonium bromide in 80 mL of deionized water. Stir the resulting solution at room temperature for 2 hours, then transfer it to a 100 mL stainless steel autoclave and heat at 120 °C for 24 hours. Collect the precipitate by centrifugation after natural cooling, and wash several times with deionized water and anhydrous ethanol. Dry under vacuum at 80 °C for 12 hours to obtain a white product. Finally, disperse 0.1 g of bismuth tungstate in 50 mL (1 mg / mL) of NaOH solution, stir for 1 hour, wash, and dry to obtain oxygen-vacancy bismuth tungstate (denoted as O-BWO).
[0031] 2) Dissolve 2.7029 g of ferric chloride hexahydrate and 0.9892 g of manganese chloride tetrahydrate in deionized water and stir for 30 minutes. Then, while stirring continuously for 1 hour, add 10 mL of 0.08 mol / L sodium hydroxide solution dropwise. Place the solution in a 100 mL stainless steel high-pressure reactor and heat at 180 °C for 10 hours. Finally, allow the solution to cool naturally to room temperature, filter, wash, and dry in a 60 °C oven for 12 hours to obtain manganese ferrite (denoted as MFO).
[0032] 3) Mix 0.1 g of bismuth tungstate and 0.0036 g of manganese ferrite and disperse them in 50 mL (1 mg / mL) of NaOH solution and stir for 2 h. Wash and dry to obtain manganese ferrite / oxygen vacancy bismuth tungstate composite material (denoted as 10MFO / O-BWO).
[0033] The O-BWO, MFO, and 10MFO / O-BWO prepared in steps 1), 2), and 3) were subjected to XRD tests, and the test results are as follows: Figure 1 As shown in the figure, typical characteristic peaks of O-BWO and MFO were detected in 10MFO / O-BWO, indicating the successful preparation of 10MFO / O-BWO.
[0034] Example 2: Photocatalytic reduction of carbon dioxide using a 10MFO / O-BWO photocatalyst
[0035] The 10MFO / O-BWO photocatalyst prepared in Example 1 was used to conduct a photocatalytic reduction experiment of carbon dioxide. The test procedure was as follows: using a 300W xenon lamp as the light source, 0.03g of the prepared O-BWO, MFO, and 10MFO / O-BWO were placed in 1mL of deionized water into a self-made sealed reaction vessel. A vacuum pump was used to evacuate the sealed vessel, and carbon dioxide gas was passed through, cyclically three times. Then, carbon dioxide was reduced under visible light irradiation. Figure 5 , 6 As shown, the manganese ferrite / bismuth tungstate photocatalyst prepared in Example 1 exhibits excellent photocatalytic activity and stability, with a carbon monoxide generation rate of 17.1 μmol / h for 10MFO / O-BWO. -1 g -1 The carbon monoxide formation rate of O-BWO is only 8.8 μmol / h. -1 g -1 .
[0036] Example 3: A manganese ferrite / bismuth tungstate photocatalyst (molar ratio of manganese ferrite to the total molar mass of the composite material is 2:10).
[0037] 1) Dissolve 0.33 g of sodium tungstate dihydrate, 0.97 g of bismuth nitrate pentahydrate, and 0.05 g of hexadecyltrimethylammonium bromide in 80 mL of deionized water. Stir the resulting solution at room temperature for 2 hours, then transfer it to a 100 mL stainless steel autoclave and heat at 120 °C for 24 hours. Collect the precipitate by centrifugation after natural cooling, and wash several times with deionized water and anhydrous ethanol. Dry under vacuum at 80 °C for 12 hours to obtain a white product. Finally, disperse 0.1 g of bismuth tungstate in 50 mL (1 mg / mL) of NaOH solution, stir for 1 hour, wash, and dry to obtain oxygen-vacancy bismuth tungstate (denoted as O-BWO).
[0038] 2) Dissolve 2.7029 g of ferric chloride hexahydrate and 0.9892 g of manganese chloride tetrahydrate in deionized water and stir for 30 minutes. Then, while stirring continuously for 1 hour, add 10 mL of 0.08 mol / L sodium hydroxide solution dropwise. Place the solution in a 100 mL stainless steel high-pressure reactor and heat at 180 °C for 10 hours. Finally, allow the solution to cool naturally to room temperature, filter, wash, and dry in a 60 °C oven for 12 hours to obtain manganese ferrite (denoted as MFO).
[0039] 3) Mix 0.1 g of bismuth tungstate and 0.008 g of manganese ferrite and disperse them in 50 mL (1 mg / mL) of NaOH solution and stir for 2 h. Wash and dry to obtain manganese ferrite / oxygen vacancy bismuth tungstate composite material (denoted as 20MFO / O-BWO).
[0040] The O-BWO, MFO, and 20MFO / O-BWO prepared in steps 1), 2), and 3) were subjected to XRD tests, and the test results are as follows: Figure 1 As shown in the figure, typical characteristic peaks of O-BWO and MFO were detected in 20MFO / O-BWO, indicating the successful preparation of 10MFO / O-BWO.
[0041] The prepared 20MFO / O-BWO was subjected to SEM testing, such as... Figure 2 , Figure 3 and Figure 4 As shown, MFO exhibits an irregular prismatic structure, while O-BWO is a flower-like structure composed of stacked nanosheets. The presence of MFO on the surface of O-BWO indicates the successful synthesis of 20MFO / O-BWO.
[0042] Example 4: Photocatalytic reduction of carbon dioxide using a 20MFO / O-BWO photocatalyst.
[0043] The 20MFO / O-BWO photocatalyst prepared in Example 3 was used to conduct a photocatalytic reduction experiment of carbon dioxide. The test procedure was as follows: using a 300W xenon lamp as the light source, 0.03g of the prepared O-BWO, MFO, and 20MFO / O-BWO were placed in a self-made sealed reaction vessel along with 1mL of deionized water. The sealed vessel was evacuated using a vacuum pump, and carbon dioxide gas was introduced through the system three times. Then, carbon dioxide was reduced under visible light irradiation. Figure 5 , 6 As shown, the manganese ferrite / bismuth tungstate photocatalyst prepared in Example 3 exhibits excellent photocatalytic activity and stability, with a carbon monoxide generation rate of 20MFO / O-BWO reaching 27.3 μmol / h. -1 g -1 The carbon monoxide formation rate of O-BWO is only 8.8 μmol / h. -1 g -1 .
[0044] Example 5: A manganese ferrite / bismuth tungstate photocatalyst (molar ratio of manganese ferrite to the total molar mass of the composite material is 3:10).
[0045] 1) Dissolve 0.33 g of sodium tungstate dihydrate, 0.97 g of bismuth nitrate pentahydrate, and 0.05 g of hexadecyltrimethylammonium bromide in 80 mL of deionized water. Stir the resulting solution at room temperature for 2 hours, then transfer it to a 100 mL stainless steel autoclave and heat at 120 °C for 24 hours. Collect the precipitate by centrifugation after natural cooling, and wash several times with deionized water and anhydrous ethanol. Dry under vacuum at 80 °C for 12 hours to obtain a white product. Finally, disperse 0.1 g of bismuth tungstate in 50 mL (1 mg / mL) of NaOH solution, stir for 1 hour, wash, and dry to obtain oxygen-vacancy bismuth tungstate (denoted as O-BWO).
[0046] 2) Dissolve 2.7029 g of ferric chloride hexahydrate and 0.9892 g of manganese chloride tetrahydrate in deionized water and stir for 30 minutes. Then, while stirring continuously for 1 hour, add 10 mL of 0.08 mol / L sodium hydroxide solution dropwise. Place the solution in a 100 mL stainless steel high-pressure reactor and heat at 180 °C for 10 hours. Finally, allow the solution to cool naturally to room temperature, filter, wash, and dry in a 60 °C oven for 12 hours to obtain manganese ferrite (denoted as MFO).
[0047] 3) Mix 0.1 g of bismuth tungstate and 0.014 g of manganese ferrite and disperse them in 50 mL (1 mg / mL) of NaOH solution and stir for 2 h. Wash and dry to obtain manganese ferrite / oxygen vacancy bismuth tungstate composite material (denoted as 30MFO / O-BWO).
[0048] The O-BWO, MFO, and 30MFO / O-BWO prepared in steps 1), 2), and 3) were subjected to XRD tests, and the test results are as follows: Figure 1 As shown in the figure, typical characteristic peaks of O-BWO and MFO were detected in 30MFO / O-BWO, indicating the successful preparation of 30MFO / O-BWO.
[0049] Example 6: Photocatalytic reduction of carbon dioxide using a 30MFO / O-BWO photocatalyst
[0050] The 30MFO / O-BWO photocatalyst prepared in Example 5 was used to conduct a photocatalytic reduction experiment of carbon dioxide. The test procedure was as follows: using a 300W xenon lamp as the light source, 0.03g of the prepared O-BWO, MFO, and 30MFO / O-BWO were placed in 1mL of deionized water into a self-made sealed reaction vessel. A vacuum pump was used to evacuate the sealed vessel, and carbon dioxide gas was passed through, repeated three times. Then, carbon dioxide was reduced under visible light irradiation. Figure 5 , 6 As shown, the manganese ferrite / bismuth tungstate photocatalyst prepared in Example 5 exhibits excellent photocatalytic activity and stability, with a carbon monoxide generation rate of 21.6 μmol / h for 30MFO / O-BWO. -1 g -1 The carbon monoxide formation rate of O-BWO is only 8.8 μmol / h. -1 g -1 .
[0051] Example 7: A manganese ferrite / bismuth tungstate photocatalyst (molar ratio of manganese ferrite to the total molar mass of the composite material is 5:10).
[0052] 1) Dissolve 0.33 g of sodium tungstate dihydrate, 0.97 g of bismuth nitrate pentahydrate, and 0.05 g of hexadecyltrimethylammonium bromide in 80 mL of deionized water. Stir the resulting solution at room temperature for 2 hours, then transfer it to a 100 mL stainless steel autoclave and heat at 120 °C for 24 hours. Collect the precipitate by centrifugation after natural cooling, and wash several times with deionized water and anhydrous ethanol. Dry under vacuum at 80 °C for 12 hours to obtain a white product. Finally, disperse 0.1 g of bismuth tungstate in 50 mL (1 mg / mL) of NaOH solution, stir for 1 hour, wash, and dry to obtain oxygen-vacancy bismuth tungstate (denoted as O-BWO).
[0053] 2) Dissolve 2.7029 g of ferric chloride hexahydrate and 0.9892 g of manganese chloride tetrahydrate in deionized water and stir for 30 minutes. Then, while stirring continuously for 1 hour, add 10 mL of 0.08 mol / L sodium hydroxide solution dropwise. Place the solution in a 100 mL stainless steel high-pressure reactor and heat at 180 °C for 10 hours. Finally, allow the solution to cool naturally to room temperature, filter, wash, and dry in a 60 °C oven for 12 hours to obtain manganese ferrite (denoted as MFO).
[0054] 3) Mix 0.1 g of bismuth tungstate and 0.0323 g of manganese ferrite and disperse them in 50 mL (1 mg / mL) of NaOH solution and stir for 2 h. Wash and dry to obtain manganese ferrite / oxygen vacancy bismuth tungstate composite material (denoted as 50MFO / O-BWO).
[0055] The O-BWO, MFO, and 50MFO / O-BWO prepared in steps 1), 2), and 3) were subjected to XRD tests, and the test results are as follows: Figure 1 As shown in the figure, typical characteristic peaks of O-BWO and MFO were detected in 50MFO / O-BWO, indicating the successful preparation of 50MFO / O-BWO.
[0056] Example 8: Photocatalytic reduction of carbon dioxide using a 50MFO / O-BWO photocatalyst.
[0057] The 50MFO / O-BWO photocatalyst prepared in Example 7 was used to conduct a photocatalytic reduction experiment of carbon dioxide. The test procedure was as follows: using a 300W xenon lamp as the light source, 0.03g of the prepared O-BWO, MFO, and 50MFO / O-BWO were placed in 1ml of deionized water into a self-made sealed reaction vessel. A vacuum pump was used to evacuate the sealed vessel, and carbon dioxide gas was passed through, cyclically three times. Then, carbon dioxide was reduced under visible light irradiation. Figure 5 , 6 As shown, the manganese ferrite / bismuth tungstate photocatalyst prepared in Example 7 exhibits excellent photocatalytic activity and stability, with a carbon monoxide generation rate of 19.1 μmol / h for 50MFO / O-BWO. -1 g -1 The carbon monoxide formation rate of O-BWO is only 8.8 μmol / h. -1 g -1 .
Claims
1. A manganese ferrite / bismuth tungstate heterojunction photocatalyst, characterized in that, The molar ratio of manganese ferrite to the total molar amount of the heterojunction photocatalyst is 1:10, 2:10, 3:10 or 5:10; The preparation method of the manganese ferrite / bismuth tungstate heterojunction photocatalyst includes the following steps: 1) Sodium tungstate dihydrate, bismuth nitrate pentahydrate, and hexadecyltrimethylammonium bromide were dissolved in deionized water and subjected to a hydrothermal reaction to obtain bismuth tungstate; 2) Dissolve ferric chloride hexahydrate and manganese chloride tetrahydrate in water, then add sodium hydroxide solution, and react hydrothermally to obtain manganese ferrate; 3) Dissolve bismuth tungstate and manganese ferrite in sodium hydroxide solution, then stir and dry to obtain manganese ferrite / bismuth tungstate heterojunction photocatalyst.
2. The manganese ferrite / bismuth tungstate heterojunction photocatalyst according to claim 1, characterized in that, In step 1), the ratio of sodium tungstate dihydrate to bismuth nitrate pentahydrate is 0.1-1 g to 0.5-1.5 g.
3. The manganese ferrite / bismuth tungstate heterojunction photocatalyst according to claim 1, characterized in that, In step 1), the amount of hexadecyltrimethylammonium bromide added is 0.05-1 g.
4. The manganese ferrite / bismuth tungstate heterojunction photocatalyst according to claim 1, characterized in that, In step 1), the hydrothermal reaction temperature is 80-150℃ and the hydrothermal reaction time is 18-36 h.
5. The manganese ferrite / bismuth tungstate heterojunction photocatalyst according to claim 1, characterized in that, In step 2), the ratio of ferric chloride hexahydrate: manganese chloride tetrahydrate: sodium hydroxide is 1-4 g: 0.5-1.5 g: 0.0008-0.001 mol.
6. The manganese ferrite / bismuth tungstate heterojunction photocatalyst according to claim 1, characterized in that, In step 2), the hydrothermal reaction temperature is 160-200℃ and the hydrothermal reaction time is 6-18 h.
7. The manganese ferrite / bismuth tungstate heterojunction photocatalyst according to claim 1, characterized in that, In step 3), the stirring time is 1-5 hours.
8. The application of the manganese ferrite / bismuth tungstate heterojunction photocatalyst according to claim 1 in the photocatalytic reduction of carbon dioxide.
9. The application according to claim 8, characterized in that, The method is as follows: Under visible light irradiation, the manganese ferrite / bismuth tungstate heterojunction photocatalyst is placed in a closed space filled with carbon dioxide gas, and the carbon dioxide gas is reduced to carbon monoxide gas.