Bismuth oxide-bismuth sulfide heterojunction capable of realizing photocatalytic conversion of sulfur hexafluoride as well as preparation method and application of bismuth oxide-bismuth sulfide heterojunction

Abstract

The invention discloses a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytic conversion of sulfur hexafluoride and a preparation method and application thereof, and the preparation method comprises the following steps: taking bismuth nitrate as a raw material, taking a mixed solution of ethanol and ethylene glycol as a solvent, and carrying out solvothermal reaction to obtain Bi2O3 nanosheets; the preparation method comprises the following steps: by taking bismuth nitrate and sodium sulfide as raw materials and a mixed solution of ethylene glycol and water as a solvent, reacting in a hydrothermal reaction device to obtain a Bi2S3 nanorod; the preparation method comprises the following steps: mixing a Bi2O3 nanosheet, a Bi2S3 nanorod and ethanol, and reacting in the presence of illumination to obtain the heterojunction. According to the invention, the Bi2O3-Bi2S3 heterojunction is prepared by a simple photodeposition method, the operation is simple, and the prepared heterojunction can be used for photocatalytic conversion of SF6 into 1-fluoropropylene and nitrile fluoride under normal pressure and light radiation; the established using method for photocatalytic conversion of SF6 is simple in condition, good in stability, environment-friendly and sustainable.

Description

Technical Field

[0001] The present invention relates to the field of material technology, and in particular to a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride, and a preparation method and application thereof. Background Art

[0002] Sulfur hexafluoride (SF 6) It is a synthetic heavy gas, in which the central sulfur atom is stably connected to the six surrounding fluorine atoms by covalent bonds, presenting an octahedral configuration. 6 It is colorless, odorless, non-flammable, slightly soluble in water, and has very stable chemical properties. Due to its unique physical and chemical properties, it has excellent insulation and arc extinguishing properties. Since the mid-1970s, sulfur hexafluoride has been used as a gas medium in electrical and electronic systems such as circuit breakers, high-voltage coaxial lines, gas-insulated substations and transformers. However, sulfur hexafluoride (SF 6 ) is a greenhouse gas that can remain in the atmosphere for up to 3,200 years and has a global warming potential (GWP) of about the same amount of CO 2 22,800 times that of SF in nature, indicating its significant impact on climate change. 6 The method is one of the problems we need to solve urgently.

[0003] The Chinese patent application document with publication number CN117960168A discloses a zinc oxide ultra-thin nanosheet capable of photocatalytically converting sulfur hexafluoride, a preparation method and application. The preparation method comprises: dissolving sodium dodecylbenzene sulfonate in a mixed solvent of water and ethanol, adding zinc chloride, stirring once at 10-18°C, then adding tetramethylammonium hydroxide aqueous solution, a mixed solvent of water and ethanol, stirring twice at 10-18°C, separating the product from the solid and liquid, washing, drying, and calcining in an air atmosphere at 600-800°C. It uses a simple precipitation method to prepare zinc oxide ultra-thin nanosheets with uniform morphology and pure phase. It can be used as a photocatalyst and photocatalytically convert sulfur hexafluoride into 1-fluoropropylene; compared with the traditional photothermal degradation of SF 6 Compared with the previous method, the synthesized zinc oxide ultrathin nanosheets are used as catalysts, which have strong catalytic ability, low energy consumption, and excellent performance. They can simply and stably convert SF 6 Gas, environmentally friendly and sustainable, but the type of catalyst disclosed is zinc oxide, which is a single type. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a catalyst capable of photocatalytically converting sulfur hexafluoride.

[0005] The present invention solves the above technical problems through the following technical means:

[0006] A method for preparing a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride comprises the following steps: using bismuth nitrate as a raw material and a mixed solution of ethanol and ethylene glycol as a solvent, performing a solvothermal reaction to obtain Bi 2 O 3 Nanosheets; using bismuth nitrate and sodium sulfide as raw materials, a mixed solution of ethylene glycol and water as solvent, reacting in a hydrothermal reaction device to obtain Bi 2 S 3 Nanorods; Bi 2 O 3 Nanosheets, Bi 2 S 3 The nanorods are mixed with ethanol and reacted under the condition of light to obtain the bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride.

[0007] Preferably, in the preparation of Bi 2 O 3 In the process of preparing the nanosheets, the dosage ratio of the bismuth nitrate and the solvent is 1.46 g:30 mL; the volume ratio of ethanol and ethylene glycol is 2:1.

[0008] Preferably, in the preparation of Bi 2 S 3 In the process of preparing the nanorods, the mass ratio of bismuth nitrate to sodium sulfide is 4.85:4.68.

[0009] Preferably, in the preparation of Bi 2 S 3 In the process of preparing the nanorods, the dosage ratio of the bismuth nitrate and the solvent is 0.485 g:70 mL; in the solvent, the volume ratio of ethylene glycol and water is 5:2.

[0010] Preferably, in the preparation of Bi 2 O 3 During the preparation of the nanosheets, the solvothermal reaction temperature was 160°C and the time was 5 h. 2 S 3 During the nanorod formation process, the reaction temperature was 160 °C and the reaction time was 12 h.

[0011] Preferably, the Bi 2 O 3 Nanosheets and Bi 2 S 3 The mass ratio of nanorods is 52:47; 2 O 3 Nanosheets, Bi 2 S 3 During the process of mixing the nanorods and ethanol, the Bi 2 O 3 The dosage ratio of nanosheets to ethanol is 0.52 g:10 ml.

[0012] Preferably, the reaction time under the condition of light is 6-8 hours; the light source is a 300W xenon lamp, and the current intensity is set to 16A.

[0013] Preferably, the bismuth nitrate is Bi(NO 3 ) 3 ·5H 2 O; the sodium sulfide is Na 2 S.9H 2 O.

[0014] The present invention also provides a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride, which is prepared by using the preparation method of the bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride.

[0015] The present invention also proposes an application of the bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride in photocatalytically converting sulfur hexafluoride to generate fluorine-containing organic matter, wherein CH 3 CN and sulfur hexafluoride are used as reaction materials for photocatalytic reaction to obtain 1-fluoropropene and fluorinated nitrile.

[0016] Preferably, the bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride is used in the photocatalytic conversion of sulfur hexafluoride to generate fluorine-containing organic matter, the reaction pressure is normal pressure, the temperature is 50-70°C, the light source used is a 300W xenon lamp, and the irradiation time is 8h-12h.

[0017] The advantages of the present invention are:

[0018] In the present invention, Bi is prepared by a simple photodeposition method. 2 O 3 -Bi 2 S 3 Heterojunction, its operation is simple, the prepared Bi 2 O 3 -Bi 2 S 3 The heterojunction can photocatalytically convert SF under normal pressure and light radiation. 6 1-fluoropropene and fluorinated nitrile; the established photocatalytic conversion of SF 6 The method has simple conditions, good stability, and is environmentally friendly and sustainable.

[0019] The present invention discloses a simple bismuth oxide-bismuth sulfide heterojunction and a new method for photothermal catalytic conversion of sulfur hexafluoride using the heterojunction. 6 Compared with the previous method, the synthesized bismuth oxide-bismuth sulfide heterojunction is used as a catalyst, which has strong catalytic ability and excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the XRD diffraction pattern of the bismuth oxide-bismuth sulfide heterojunction prepared in Example 1 of the present invention;

[0021] Figure 2 This is a high-resolution transmission electron microscopy image (HRTEM) of the bismuth oxide-bismuth sulfide heterojunction prepared in Example 1 of the present invention;

[0022] Figure 3 This is a transmission electron microscope image (TEM) of the bismuth oxide-bismuth sulfide heterojunction prepared in Example 1 of the present invention;

[0023] Figure 4 The X-ray photoelectron spectroscopy (XPS) Bi spectrum of the bismuth oxide-bismuth sulfide heterojunction prepared in Example 1 of the present invention;

[0024] Figure 5 is an X-ray photoelectron spectroscopy (XPS) O spectrum of the bismuth oxide-bismuth sulfide heterojunction prepared in Example 1 of the present invention;

[0025] Figure 6 is an X-ray photoelectron spectroscopy (XPS) S spectrum of the bismuth oxide-bismuth sulfide heterojunction prepared in Example 1 of the present invention;

[0026] Figure 7 This is the NMR spectrum of the liquid product obtained by photocatalytic conversion of sulfur hexafluoride by the bismuth oxide-bismuth sulfide heterojunction prepared in Example 1 of the present invention;

[0027] Figure 8 is a transmission electron microscope image of the sample prepared in Example 3 of the present invention;

[0028] Fig. 9 The XRD diffraction pattern of the sample prepared in Example 3 of the present invention;

[0029] Fig.10 This is a transmission electron microscope image of the sample prepared in Comparative Example 1 of the present invention;

[0030] Fig.11 This is the NMR spectrum of the liquid product obtained by photocatalytic conversion of sulfur hexafluoride by the bismuth oxide-bismuth sulfide heterojunction prepared in Example 3 of the present invention;

[0031] Fig.12 This is the NMR spectrum of the liquid phase product obtained in Comparative Example 2 of the present invention;

[0032] Fig.13 This is the NMR spectrum of the liquid product obtained in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with 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 creative work are within the scope of protection of the present invention.

[0034] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0035] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0036] Example 1

[0037] A method for preparing a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride comprises the following steps:

[0038] Add 1.46g Bi(NO 3 ) 3 ·5H 2 O was added to a mixed solution of 20 mL ethanol and 10 mL ethylene glycol, stirred at room temperature for 3 h, and the mixture was transferred to a 50 mL polytetrafluoroethylene-lined autoclave, sealed and heated at 160 ° C for 5 h. After the reaction was completed, it was naturally cooled to room temperature and centrifuged. The obtained product was washed with ethanol and water, and then placed in a vacuum drying oven for 12 h to obtain Bi 2 O 3 Nanosheets were stored in a desiccator for later use.

[0039] Add 0.485g Bi(NO 3 ) 3 ·5H 2 O and 0.468g Na 2 S.9H 2 O was added to a mixed solution of 50 mL ethylene glycol and 20 mL water, and after stirring evenly, the mixture was transferred to a 100 mL polytetrafluoroethylene-lined autoclave, sealed and heated at 160 ° C for 12 h. After the reaction was completed, it was naturally cooled to room temperature and centrifuged. The obtained product was washed with ethanol and water, and then placed in a vacuum drying oven for 12 h to obtain Bi 2 S 3 Nanorods were stored in a desiccator until use.

[0040] Put 0.52g Bi 2 O 3 Nanosheets and 0.47 g Bi 2 S3 The nanorods were added to 10 ml of ethanol and stirred for 7 h under 300 W xenon light with a current intensity of 16 A. The obtained product was washed with water and then dried in a vacuum drying oven for 12 h to obtain bismuth oxide-bismuth sulfide (Bi 2 O 3 -Bi 2 S 3 ) heterojunction.

[0041] The structure of the compound prepared in Example 1 was identified. Figure 1 to Figure 6 ,Depend on Figure 1 It can be seen that the synthesized Bi 2 O 3 Nanosheets and Bi 2 S 3 The nanorods conform to the standard spectra JCPDS.card.No.74-1374 and JCPDS.card.No.75-1306, respectively, which indicates that the synthesized Bi 2 O 3 Nanosheets and Bi 2 S 3 The nanorods belong to the orthorhombic and rhombic systems respectively, and the Bi 2 O 3 -Bi 2 S 3 The heterojunction host conforms to the extremely crystalline Bi 2 S 3 Standard spectrum, its XRD pattern ( Figure 1 Zhongbi 2 S 3 @Bi 2 O 3 As shown) in Bi 2 O 3 The peak value of the diffraction standard spectrum with a larger diffraction angle drifts upward, which well illustrates that Bi 2 O 3 -Bi 2 S 3 Bi in heterojunction 2 O 3 and Bi 2 S 3 existence.

[0042] Depend on Figure 2 Bi 2 O 3 -Bi 2 S 3 The high-resolution transmission image of the heterojunction shows that Bi 2 O 3 Nanosheets and Bi 2 S 3The growth directions of the nanorods are (0 1 0) and (1 0 0), respectively. 2 O 3 The exposed crystal planes are mainly (0 0 3) and (4 0 0), with the interplanar spacings of 0.26nm and 0.18nm respectively. 2 S 3 The exposed crystal planes are mainly (0 8 0) and (0 0 2), and the spacing between the two crystal planes is 0.35nm and 0.25nm respectively. At the same time, it can be clearly seen from the figure that the lattice distortion overlaps at the junction of the nanosheet and the nanorod, which is Bi 2 O 3 -Bi 2 S 3 The formation of heterojunction provides direct evidence.

[0043] Depend on Figure 3 Bi 2 O 3 -Bi 2 S 3 The TEM image of the heterojunction shows that the lateral size of Bi is between 400 and 200 nm. 2 O 3 Nanosheets and Bi 2 S 3 The nanorods are bonded together in layers.

[0044] Depend on Figure 4 , 5 , 6, we can see that from Bi 2 O 3 -Bi 2 S 3 The X-ray photoelectron spectrum of the heterojunction Bi 4f shows that Bi 2 O 3 and Bi 2 S 3 The overall valence state has not changed, and some electrons have been transferred from Bi 2 O 3 Moved to Bi 2 S 3 The X-ray photoelectron spectrum of S1s is basically consistent with Bi 2 S 3 The binding energy of S in .

[0045] Example 2

[0046] Bi 2 O 3 -Bi 2 S 3 Heterojunction photocatalytic degradation of SF 6 Example of generating 1-fluoropropene:

[0047] 10 mg of Bi prepared in Example 1 was added 2 O 3 -Bi 2 S 3 The heterojunction powder was dispersed in 2 mL H 2 O, the obtained dispersion was spin-dropped on quartz glass and heat-treated at 60°C for 2 hours to obtain a photocatalyst-based thin film. 8 mL of CH 3 CN, use a quartz column to remove the bottom CH 3 The CN liquid is separated from the photocatalyst-based film, and then the reaction system is evacuated, and then high-purity sulfur hexafluoride gas with a purity of 99.999% is filled into it to reach normal pressure. Then 60°C circulating water is introduced, and a 300W xenon lamp is used to simulate the sunlight source. After irradiation for 10 hours, a certain amount of 1-fluoropropene and fluorinated nitrile are obtained. Figure 7 The prepared Bi 2 O 3 -Bi 2 S 3 NMR fluorine spectra of 1-fluoropropene and fluorinated nitrile obtained by heterojunction photocatalytic conversion of sulfur hexafluoride.

[0048] Example 3

[0049] A method for preparing a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride comprises the following steps:

[0050] 0.52 g of Bi prepared in Example 1 2 O 3 Nanosheets and 0.47 g of Bi prepared in Example 1 2 S 3 The nanorods were added to 10 ml of ethanol and stirred for 6 h under 300 W xenon light with a current intensity of 16 A. The obtained product was washed with water and then dried in a vacuum drying oven for 12 h to obtain Bi 2 O 3 -Bi 2 S 3 Heterojunction. Fig. 9 is the XRD diffraction pattern of the prepared sample. Figure 8 For the preparation of Bi 2 O 3 -Bi 2 S 3 Transmission electron microscope image of the heterojunction. Figure 8 It can be seen that the Bi with lateral dimensions ranging from 400 to 200 nm 2 O 3 Nanosheets and Bi 2 S 3 Nanorods are stacked together. Fig. 9 It can be seen that the Bi obtained by photodeposition 2 O3 -Bi 2 S 3 The heterojunction host conforms to the extremely crystalline Bi 2 S 3 Standard spectrum, its XRD pattern (Bi 2 S 3 @Bi 2 O 3 As shown) in Bi 2 O 3 The peak value of the diffraction standard spectrum with a larger diffraction angle drifts upward, which well illustrates that Bi 2 O 3 -Bi 2 S 3 Bi in heterojunction 2 O 3 and Bi 2 S 3 existence.

[0051] Comparative Example 1

[0052] 0.52 g of Bi prepared in Example 1 2 O 3 Nanosheets and 0.47 g of Bi prepared in Example 1 2 S 3 The nanorods were added to 10 ml of water and stirred for 7 h under 300 W xenon light with a current intensity of 16 A. The obtained product was washed with water and then dried in a vacuum drying oven for 12 h. The obtained sample morphology is as follows: Fig.10 As shown by Fig.10 It can be seen that the samples are clustered together, not that bismuth oxide nanosheets grow on bismuth sulfide nanorods.

[0053] Example 4

[0054] Bi 2 O 3 -Bi 2 S 3 Heterojunction photocatalytic degradation of SF 6 Example of generating 1-fluoropropene:

[0055] 10 mg of Bi prepared in Example 3 was added 2 O 3 -Bi 2 S 3 The heterojunction powder was dispersed in 2 mL H 2 O, the obtained dispersion was spin-dropped on quartz glass and heat-treated at 60°C for 2 hours to obtain a photocatalyst-based thin film. 8 mL of CH 3 CN, use a quartz column to remove the bottom CH 3The CN liquid is separated from the photocatalyst-based film, and then the reaction system is evacuated, and then high-purity sulfur hexafluoride gas with a purity of 99.999% is filled into it to reach normal pressure. Then 50°C circulating water is introduced, and a 300W xenon lamp is used to simulate the sunlight source. After irradiation for 10 hours, a certain amount of 1-fluoropropylene and fluorinated nitrile are obtained. Fig.11 The prepared Bi 2 O 3 -Bi 2 S 3 NMR fluorine spectra of 1-fluoropropene and fluorinated nitrile obtained by heterojunction photocatalytic conversion of sulfur hexafluoride.

[0056] Comparative Example 2

[0057] 10 mg of Bi prepared in Example 1 2 O 3 -Bi 2 S 3 The powder was dispersed in 2 mL of H 2 O, the obtained dispersion was spin-dropped on quartz glass and heat-treated at 60°C for 2 hours to obtain a photocatalyst-based film. 8 mL of H 2 O, use a quartz column to remove the bottom liquid H 2 O is separated from the photocatalyst-based film, and then the reaction system is evacuated, and then high-purity sulfur hexafluoride gas with a purity of 99.999% is filled into it to reach normal pressure. Then 60℃ circulating water is introduced, and a 300W xenon lamp is used to simulate the sunlight source. After irradiation for 10 hours, the liquid phase nuclear magnetic fluorine spectrum is obtained as follows Fig.12 As shown by Fig.12 It can be seen that no product was generated.

[0058] Comparative Example 3

[0059] The only difference from Example 2 is that the product prepared in Comparative Example 1 is used instead of Bi prepared in Example 1. 2 O 3 -Bi 2 S 3 Heterojunction powder. Fig.13 This is the NMR fluorine spectrum after the reaction, which shows that no product is generated.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride, characterized in that: The following steps are involved: Bismuth nitrate is used as a raw material and a mixed solution of ethanol and ethylene glycol is used as a solvent to carry out a solvothermal reaction to obtain Bi2O3 nanosheets; bismuth nitrate and sodium sulfide are used as raw materials and a mixed solution of ethylene glycol and water is used as a solvent to carry out a reaction in a hydrothermal reaction device to obtain Bi2S3 nanorods; the Bi2O3 nanosheets, Bi2S3 nanorods and ethanol are mixed and reacted under the condition of light to obtain the bismuth oxide-bismuth sulfide heterojunction capable of photocatalytic conversion of sulfur hexafluoride.

2. The method for preparing a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytic conversion of sulfur hexafluoride according to claim 1, characterized in that: In the process of preparing Bi2O3 nanosheets, the usage ratio of bismuth nitrate and solvent is 1.46 g:30 mL; the volume ratio of ethanol and ethylene glycol is 2:

1.

3. The method for preparing a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytic conversion of sulfur hexafluoride according to claim 1, characterized in that: In the process of preparing Bi2S3 nanorods, the mass ratio of bismuth nitrate to sodium sulfide is 4.85:4.

68.

4. The method for preparing a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytic conversion of sulfur hexafluoride according to claim 1, characterized in that: In the process of preparing Bi2S3 nanorods, the usage ratio of bismuth nitrate and solvent is 0.485g:70mL; in the solvent, the volume ratio of ethylene glycol and water is 5:

2.

5. The method for preparing a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytic conversion of sulfur hexafluoride according to claim 1, characterized in that: In the process of preparing Bi2O3 nanosheets, the temperature of the solvothermal reaction is 160°C and the time is 5 hours; in the process of preparing Bi2S3 nanorods, the reaction temperature is 160°C and the time is 12 hours.

6. The method for preparing a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytic conversion of sulfur hexafluoride according to claim 1, characterized in that: The mass ratio of the Bi2O3 nanosheets to the Bi2S3 nanorods is 52:47; in the process of uniformly mixing the Bi2O3 nanosheets, Bi2S3 nanorods and ethanol, the usage ratio of the Bi2O3 nanosheets to ethanol is 0.52g:10ml.

7. The method for preparing a bismuth oxide-bismuth sulfide heterojunction capable of photocatalytic conversion of sulfur hexafluoride according to any one of claims 1 to 6, characterized in that: The reaction time under the condition of light is 6-8 hours; the light source is a 300W xenon lamp, and the current intensity is set to 16A.

8. A bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride, characterized in that: The bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride is prepared by the method for preparing the bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride as described in any one of claims 1 to 7.

9. Use of the bismuth oxide-bismuth sulfide heterojunction capable of photocatalytically converting sulfur hexafluoride as claimed in claim 8 in photocatalytically converting sulfur hexafluoride to generate fluorine-containing organic matter, characterized in that: The method uses CH3CN and sulfur hexafluoride as reaction raw materials to carry out photocatalytic reaction to obtain 1-fluoropropene and fluorinated nitrile.

10. Use of the bismuth oxide-bismuth sulfide heterojunction capable of photocatalytic conversion of sulfur hexafluoride according to claim 9 in photocatalytic conversion of sulfur hexafluoride to generate fluorine-containing organic matter, characterized in that: The reaction pressure is normal pressure, the temperature is 50-70°C, the light source used is a 300W xenon lamp, and the irradiation time is 8h-12h.

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