Preparation method of two-dimensional subnanometer ortho-position vanadium-oxygen double-defect bismuth-rich bismuth vanadate photocatalyst and application of photocatalyst in catalyzing water to desorb oxygen
By preparing a two-dimensional sub-nanometer bismuth-vanadium-oxygen dual-defect bismuth-rich vanadate photocatalyst, the problems of low photogenerated carrier separation efficiency and difficult hole extraction of existing bismuth-rich bismuth vanadate photocatalysts were solved, and a more efficient photocatalytic oxygen evolution reaction was achieved.
Patent Information
- Application Number
- CN202511493785.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-20
- Publication Date
- 2025-12-02
AI Technical Summary
Existing bismuth-rich bismuth vanadate photocatalysts have low photogenerated carrier separation efficiency, difficulty in hole extraction, and lack of water activation sites, which limits their activity in the photocatalytic oxygen evolution reaction.
By preparing a two-dimensional sub-nanometer bismuth vanadate photocatalyst with adjacent vanadium-oxygen double defects, a surfactant was introduced to limit the particle synthesis rate and form a sub-nanometer structure. The vanadium-oxygen layer was etched using a passivation reduction method with polyvinylpyrrolidone and ethylene glycol to form defect sites to promote charge separation and water activation.
It improves the directional transfer and separation efficiency of photogenerated holes, enhances the adsorption and activation capacity of water, and improves the efficiency of photocatalytic water splitting and oxygen evolution, generating 1.4 millimoles of oxygen per gram of catalyst.
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Figure CN121042011A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a photocatalyst and its application. Background Technology
[0002] The recent global energy crisis and increasingly severe environmental problems have led to greater focus on finding efficient, stable, and sustainable energy sources. Semiconductor-based photocatalysis technology can utilize abundant and virtually inexhaustible solar energy, and is therefore considered a promising and cost-effective method for producing clean and renewable energy. In photocatalysis, the slow relaxation process of the water oxidation oxygen evolution half-reaction is a key step determining the photocatalytic reaction rate. Therefore, the rational design and preparation of efficient, inexpensive, and stable water oxidation oxygen evolution photocatalysts are of great significance for improving photocatalytic efficiency.
[0003] Among numerous photocatalysts, bismuth-rich bismuth vanadate, as a novel bismuth vanadate-based catalyst, possesses a deeper valence band and a unique Aurivillius layered structure, resulting in stronger oxidation capabilities. Its unique piezoelectric characteristics and easily tunable spatial structure also make it a highly promising material for the photocatalytic water splitting and oxygen evolution reaction (OER). However, the unique structural factors of bismuth-rich bismuth vanadate lead to low photogenerated carrier separation efficiency and poor hole extraction ability, significantly limiting its OER activity. Therefore, defects can be constructed to form hole transport channels, promoting charge separation and transfer processes, thereby enhancing the photocatalytic OER activity.
[0004] However, current designs for bismuth-rich bismuth vanadate photocatalysts typically produce samples that are bulk and irregular in shape. To promote the separation and transfer of photogenerated charges, the method of constructing heterojunctions is often used, which results in low separation efficiency, difficulty in hole extraction, and a lack of water activation sites. There are no reports on the regulation of the material itself. Summary of the Invention
[0005] The purpose of this invention is to address the problems of low photogenerated carrier separation efficiency, difficulty in hole extraction, and lack of water activation sites in bismuth-rich vanadate photocatalysts prepared by existing technologies. The invention provides a method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-rich vanadate photocatalyst and its application in catalytic water desorption of oxygen.
[0006] A method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-rich vanadate photocatalyst is carried out according to the following steps:
[0007] I. Preparation of two-dimensional sub-nanometer bismuth-rich vanadate:
[0008] ① Disperse the bismuth source and urea in an alcohol solvent and stir until completely dissolved to obtain solution A; disperse the surfactant in an alcohol solvent and stir until completely dissolved to obtain solution B; mix solution A and solution B, add ammonium metavanadate, adjust the pH of the system to weakly acidic, and continue stirring to obtain a suspension;
[0009] ② Transfer the suspension to a high-pressure reactor and perform a hydrothermal reaction at 180°C for a period of time. Then, allow it to cool naturally to room temperature to obtain reaction product I.
[0010] ③ Centrifuge reaction product I to remove the supernatant and obtain precipitate I; wash precipitate I, dry it, and finally calcine it to obtain bismuth-rich bismuth vanadate nanosheets.
[0011] II. Preparation of two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalysts:
[0012] ① Disperse bismuth-rich bismuth vanadate nanosheets in an acid solution, heat and stir to obtain reaction product II;
[0013] ② Centrifuge reaction product II to remove the supernatant and obtain precipitate II; wash precipitate II and dry it to obtain dried precipitate II.
[0014] ③ Add the polymer and organic solvent to deionized water to form a uniform and stable solution C. Disperse the dried precipitate II into solution C and continue stirring to obtain a suspension.
[0015] ④ Transfer the suspension to a high-pressure reactor and then perform a hydrothermal reaction at 120°C. Allow it to cool naturally to room temperature to obtain reaction product III.
[0016] ⑤ Centrifuge the reaction product Ⅲ to remove the supernatant and obtain precipitate Ⅲ; wash precipitate Ⅲ, dry it, and finally calcine it to obtain a two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst.
[0017] A two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalyst is used as a photocatalyst for the desorption of oxygen from water.
[0018] The principle of this invention:
[0019] This invention first coordinates bismuth nitrate with ammonium metavanadate in a weakly acidic environment, introduces a surfactant to limit the synthesis rate of particles, and forms a sub-nanometer bismuth-rich bismuth vanadate. Then, it uses the principle of bismuth-chlorine interaction in hydrochloric acid to etch and obtain a bismuth-rich bismuth vanadate with exposed vanadium-oxygen layer. Furthermore, it uses a passivation reduction self-assembly method with polyvinylpyrrolidone and ethylene glycol to obtain a two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich bismuth vanadate photocatalyst.
[0020] Advantages of this invention:
[0021] I. The two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalyst prepared in this invention and existing vanadate photocatalysts
[0022] Compared to bismuth-based photocatalysts, the introduction of defects facilitates the directional transfer and separation of photogenerated holes;
[0023] II. The two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-vanadate photocatalyst prepared by this invention is more conducive to water adsorption and activation due to the presence of defect sites.
[0024] III. The two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-vanadate photocatalyst prepared by the present invention is suitable for photocatalytic decomposition of water to produce oxygen. Each gram of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-vanadate photocatalyst can generate 1.4 mmol / g of oxygen through photocatalytic decomposition of water to produce oxygen.
[0025] A two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalyst is used as a photocatalyst for the desorption of oxygen from water. Attached Figure Description
[0026] Figure 1 This is the X-ray diffraction pattern of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1.
[0027] Figure 2 This is a transmission electron microscope image of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1.
[0028] Figure 3 This is an atomic force microscope image of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1.
[0029] Figure 4 This is the hydroxyl radical spectrum of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1.
[0030] Figure 5 This is the UV-Vis diffuse reflectance of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1.
[0031] Figure 6 This is a photocatalytic oxygen evolution activity diagram of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1;
[0032] Figure 7The bar charts show the photocatalytic water oxidation oxygen evolution of the two-dimensional sub-nanometer bismuth-rich vanadate photocatalyst prepared in Comparative Example 1, the two-dimensional sub-nanometer bismuth-rich vanadate photocatalyst with exposed vanadium-oxygen layer prepared in Comparative Example 2, and the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalyst prepared in Experiment 1. Detailed Implementation
[0033] Specific Implementation Method 1: This implementation method is a preparation method of a two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-vanadate-rich photocatalyst, which is completed according to the following steps:
[0034] I. Preparation of two-dimensional sub-nanometer bismuth-rich vanadate:
[0035] ① Disperse the bismuth source and urea in an alcohol solvent and stir until completely dissolved to obtain solution A; disperse the surfactant in an alcohol solvent and stir until completely dissolved to obtain solution B; mix solution A and solution B, add ammonium metavanadate, adjust the pH of the system to weakly acidic, and continue stirring to obtain a suspension;
[0036] ② Transfer the suspension to a high-pressure reactor and perform a hydrothermal reaction at 180°C for a period of time. Then, allow it to cool naturally to room temperature to obtain reaction product I.
[0037] ③ Centrifuge reaction product I to remove the supernatant and obtain precipitate I; wash precipitate I, dry it, and finally calcine it to obtain bismuth-rich bismuth vanadate nanosheets.
[0038] II. Preparation of two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalysts:
[0039] ① Disperse bismuth-rich bismuth vanadate nanosheets in an acid solution, heat and stir to obtain reaction product II;
[0040] ② Centrifuge reaction product II to remove the supernatant and obtain precipitate II; wash precipitate II and dry it to obtain dried precipitate II.
[0041] ③ Add the polymer and organic solvent to deionized water to form a uniform and stable solution C. Disperse the dried precipitate II into solution C and continue stirring to obtain a suspension.
[0042] ④ Transfer the suspension to a high-pressure reactor and then perform a hydrothermal reaction at 120°C. Allow it to cool naturally to room temperature to obtain reaction product III.
[0043] ⑤ Centrifuge the reaction product Ⅲ to remove the supernatant and obtain precipitate Ⅲ; wash precipitate Ⅲ, dry it, and finally calcine it to obtain a two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst.
[0044] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the bismuth source mentioned in step one ① is bismuth nitrate; the alcohol solvent mentioned in step one ① is ethylene glycol; and the surfactant mentioned in step one ① is hexadecyltrimethylammonium bromide. The other steps are the same as in Specific Implementation Method One.
[0045] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: in step one ①, the mass-to-volume ratio of bismuth source, urea, and alcohol solvent in solution A is (2.425g~12.125g):(1.00g~5.00g):(35mL~175mL); in step one ①, the mass-to-volume ratio of surfactant to alcohol solvent in solution B is (1.00g~5.00g):(35mL~175mL). The other steps are the same as in Specific Implementation Method One or Two.
[0046] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the mass ratio of ammonium metavanadate to the volume ratio of alcohol solvent in solution A in step one ① is (0.3g~1.5g):(35mL~175mL); the stirring speed in step one ① is 300r / min~500r / min. Other steps are the same as in Specific Implementation Methods One to Three.
[0047] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: in step one ①, solution A and solution B are mixed, then ammonium metavanadate is added, the pH of the system is adjusted to 4-5, and stirring is continued for 20-30 minutes to obtain a suspension; the hydrothermal reaction time mentioned in step one ② is 20-24 hours. Other steps are the same as in Specific Implementation Methods One to Four.
[0048] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in the following ways: In step one to three, the precipitate I is centrifuged and washed sequentially with deionized water and anhydrous ethanol at a speed of 3000 r / min to 4000 r / min, for a total of 10 to 15 times, with each centrifugation lasting 10 to 15 minutes; the drying temperature in step one to three is 60℃ to 80℃, and the drying time is 12 to 24 hours; the calcination temperature in step one to three is 400℃ to 450℃, and the calcination time is 8 to 12 minutes. The other steps are the same as in Specific Implementation Methods One to Five.
[0049] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in the following ways: the acid solution mentioned in step two ① is hydrochloric acid with a concentration of 0.036 g / L to 0.182 g / L; the heating and stirring temperature in step two ① is 40℃ to 50℃, the stirring speed is 100 r / min to 300 r / min, and the time is 30 min to 40 min; the polymer mentioned in step two ③ is polyvinylpyrrolidone; and the organic solvent in step two ③ is ethylene glycol. The other steps are the same as in Specific Implementation Methods One to Six.
[0050] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in the following ways: In step two, the mass-to-volume ratio of bismuth-rich bismuth vanadate nanosheets, polymer, organic solvent, and deionized water is (0.1g~0.2g):(0.2g~0.4g):(0.05mL~0.2mL):(15mL~30mL); the washing in step two involves sequential centrifugation with deionized water and anhydrous ethanol at a speed of 3000r / min~4000r / min, for a total of 3~6 times, with each centrifugation lasting 5min~10min; the drying temperature in step two is 60℃~80℃, and the drying time is 12h~24h. Other steps are the same as in Specific Implementation Methods One to Seven.
[0051] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in the following ways: In step two ①, the mass ratio of the bismuth-rich bismuth vanadate nanosheets to the volume ratio of the acid solution is (0.1g~0.2g):(20mL~40mL); in step two ③, the stirring time is 20min~30min; in step two ④, the hydrothermal reaction time is 3h~4h; in step two ⑤, the calcination temperature is 400℃~450℃, and the calcination time is 8min~12min. The other steps are the same as in Specific Implementation Methods One to Eight.
[0052] Specific Implementation Method 10: This implementation method is a two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalyst used as a photocatalyst for the desorption of oxygen from water.
[0053] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0054] Experiment 1: A method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-rich vanadate photocatalyst, which is carried out according to the following steps:
[0055] I. Preparation of two-dimensional sub-nanometer bismuth-rich vanadate:
[0056] ① Disperse 2.425g of bismuth nitrate and 1g of urea in 35mL of ethylene glycol and stir until completely dissolved to obtain solution A; disperse 1.00g of hexadecyltrimethylammonium bromide in 35mL of ethylene glycol and stir until completely dissolved to obtain solution B; mix solution A and solution B, add 0.3g of ammonium metavanadate, adjust the pH of the system to 4, and continue stirring for 30min to obtain a suspension;
[0057] ② Transfer the suspension to a high-pressure reactor and hydrothermally react at 180°C for 24 hours. Allow it to cool naturally to room temperature to obtain reaction product I.
[0058] ③ Centrifuge reaction product I to remove the supernatant and obtain precipitate I; wash precipitate I by centrifugation with deionized water and anhydrous ethanol five times each, dry at 60℃ for 12h, and finally calcine at 450℃ for 8min to obtain bismuth-rich bismuth vanadate nanosheets.
[0059] The stirring speed mentioned in step 1① is 500 r / min;
[0060] The centrifugal cleaning speed described in step 1③ is 3000 r / min, and the centrifugal cleaning time is 10 min each time;
[0061] II. Preparation of two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalysts:
[0062] ① Disperse 0.1g of bismuth-rich bismuth vanadate nanosheets into 20mL of hydrochloric acid with a concentration of 0.182g / L, heat and stir at 45℃ for 30min, and stir at a speed of 300r / min to obtain reaction product II;
[0063] ② Centrifuge reaction product II to remove the supernatant and obtain precipitate II; wash precipitate II by centrifugation with deionized water and anhydrous ethanol three times each, and then dry it at 60℃ for 12 hours to obtain dried precipitate II.
[0064] ③ Add 0.2g of polyvinylpyrrolidone and 0.084mL of ethylene glycol to 15mL of deionized water to form a homogeneous and stable solution C. Disperse the dried precipitate II into solution C and continue stirring for 30min to obtain a suspension.
[0065] ④ Transfer the suspension to a high-pressure reactor and then perform a hydrothermal reaction at 120°C for 3 hours. Allow it to cool naturally to room temperature to obtain reaction product III.
[0066] ⑤ Centrifuge the reaction product Ⅲ to remove the supernatant and obtain precipitate Ⅲ; use deionized water and anhydrous ethanol to centrifuge and wash the precipitate Ⅲ three times each, then dry it at 60℃ for 12h, and finally calcine it at 450℃ for 8min to obtain a two-dimensional sub-nanometer ortho-vanadium-oxygen double defect bismuth vanadate rich photocatalyst.
[0067] The centrifugal cleaning speed in step two is 3000 r / min, and the centrifugal cleaning time is 5 min each time.
[0068] Figure 1 This is the X-ray diffraction pattern of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1.
[0069] Depend on Figure 1 It can be seen that the introduction of vanadium-oxygen double defects did not change the crystal phase and crystallinity of bismuth-rich bismuth vanadate.
[0070] Figure 2 This is a transmission electron microscope image of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1.
[0071] Depend on Figure 2 It can be seen that the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1 has an ultra-thin two-dimensional sheet structure, which is conducive to rapid charge transfer and separation.
[0072] Figure 3 This is an atomic force microscope image of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1.
[0073] Depend on Figure 3 It can be seen that the thickness of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalyst prepared in Experiment 1 is less than 1 nanometer, indicating that a sub-nanometer structure of bismuth-rich vanadate was synthesized.
[0074] Figure 4 This is the hydroxyl radical spectrum of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1.
[0075] Depend on Figure 4 It can be seen that the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1 has an extremely strong hydroxyl radical signal, indicating that it has good charge separation ability.
[0076] The two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1 was detected using ultraviolet-visible diffuse reflectance spectroscopy. The detection results are as follows: Figure 5 As shown;
[0077] Figure 5This is the UV-Vis diffuse reflectance of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1.
[0078] Depend on Figure 5 It can be seen that the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalyst prepared in Experiment 1 has a wide visible light response, proving that it has extremely strong visible light absorption.
[0079] 0.05 g of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1 was added to 100 mL of distilled water, and then transferred to a 250 mL quartz glass reactor. A visible light intensity of 400 mW / cm² was used. 2 The quartz glass reactor was irradiated with visible light, and the gas inside was extracted every 0.5 hours. The gas was then detected using chromatography. The results are shown in the figure. Figure 6 As shown;
[0080] Figure 6 This is a photocatalytic oxygen evolution activity diagram of the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst prepared in Experiment 1;
[0081] Depend on Figure 6 It can be seen that the change of photocatalytic oxygen evolution over time is not linear. Due to the reduction of the co-catalyst and its attachment to the catalyst surface, the catalyst surface cannot be exposed to light, resulting in a gradual decrease in activity. Its performance is optimal after half an hour.
[0082] Comparing with Example 1: The preparation method of the two-dimensional sub-nanometer bismuth-rich vanadate photocatalyst is specifically completed according to the following steps:
[0083] ① Disperse 2.425g of bismuth nitrate and 1g of urea in 35mL of ethylene glycol and stir until completely dissolved to obtain solution A; disperse 1.00g of hexadecyltrimethylammonium bromide in 35mL of ethylene glycol and stir until completely dissolved to obtain solution B; mix solution A and solution B, add 0.3g of ammonium metavanadate, adjust the pH of the system to 4, and continue stirring for 30min to obtain a suspension;
[0084] ② Transfer the suspension to a high-pressure reactor and hydrothermally react at 180°C for 24 hours. Allow it to cool naturally to room temperature to obtain reaction product I.
[0085] ③ Centrifuge reaction product I to remove the supernatant and obtain precipitate I; wash precipitate I by centrifugation with deionized water and anhydrous ethanol five times each, dry at 60℃ for 12h, and finally calcine at 450℃ for 8min to obtain a two-dimensional sub-nanometer bismuth-rich vanadate photocatalyst.
[0086] Comparative Example 2: The preparation method of a two-dimensional sub-nanometer bismuth-rich bismuth vanadate photocatalyst with exposed vanadium-oxygen layer is specifically carried out according to the following steps:
[0087] I. Preparation of two-dimensional sub-nanometer bismuth-rich vanadate:
[0088] ① Disperse 2.425g of bismuth nitrate and 1g of urea in 35mL of ethylene glycol and stir until completely dissolved to obtain solution A; disperse 1.00g of hexadecyltrimethylammonium bromide in 35mL of ethylene glycol and stir until completely dissolved to obtain solution B; mix solution A and solution B, add 0.3g of ammonium metavanadate, adjust the pH of the system to 4, and continue stirring for 30min to obtain a suspension;
[0089] ② Transfer the suspension to a high-pressure reactor and hydrothermally react at 180°C for 24 hours. Allow it to cool naturally to room temperature to obtain reaction product I.
[0090] ③ Centrifuge reaction product I to remove the supernatant and obtain precipitate I; wash precipitate I by centrifugation with deionized water and anhydrous ethanol five times each, dry at 60℃ for 12h, and finally calcine at 450℃ for 8min to obtain bismuth-rich bismuth vanadate nanosheets.
[0091] The stirring speed mentioned in step 1① is 500 r / min;
[0092] The centrifugal cleaning speed described in step 1③ is 3000 r / min, and the centrifugal cleaning time is 10 min each time;
[0093] II. ① Disperse 0.1g of bismuth-rich bismuth vanadate nanosheets into 20mL of hydrochloric acid with a concentration of 0.182g / L, heat and stir at 45℃ for 30min, and stir at a speed of 300r / min to obtain reaction product II.
[0094] ② Centrifuge reaction product II to remove the supernatant and obtain precipitate II; wash precipitate II by centrifugation with deionized water and anhydrous ethanol three times each, and then dry it at 60℃ for 12h to obtain a two-dimensional sub-nanometer bismuth-rich vanadate photocatalyst with exposed vanadium oxide layer.
[0095] The centrifugal cleaning speed is 3000 r / min, and the centrifugal cleaning time is 5 min each time.
[0096] Figure 6 This is a graph showing the change in oxygen evolution rate over time caused by the photocatalyst, based on... Figure 6 The optimal photocatalytic performance was found to be 30 minutes.
[0097] Quantitative analysis of the photocatalytic oxygen evolution activity of three photocatalysts after half an hour was performed, see [reference needed]. Figure 7 As shown;
[0098] Figure 7 The bar chart shows the photocatalytic water oxidation oxygen evolution of the two-dimensional sub-nanometer bismuth-rich vanadate photocatalyst prepared in Comparative Example 1, the two-dimensional sub-nanometer bismuth-rich vanadate photocatalyst with exposed vanadium-oxygen layer prepared in Comparative Example 2, and the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalyst prepared in Experiment 1.
[0099] Depend on Figure 7 It can be seen that the two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-vanadate photocatalyst prepared in Experiment 1 is beneficial for the photocatalytic desorption of oxygen from water.
Claims
1. A method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-vanadate-rich photocatalyst, characterized in that... The preparation method is completed according to the following steps: I. Preparation of two-dimensional sub-nanometer bismuth-rich vanadate: ① Disperse the bismuth source and urea in an alcohol solvent and stir until completely dissolved to obtain solution A; disperse the surfactant in an alcohol solvent and stir until completely dissolved to obtain solution B; Mix solution A with solution B, then add ammonium metavanadate to adjust the pH of the system to weakly acidic, and continue stirring to obtain a suspension; ② Transfer the suspension to a high-pressure reactor and perform a hydrothermal reaction at 180°C for a period of time. Then, allow it to cool naturally to room temperature to obtain reaction product I. ③ Centrifuge reaction product I to remove the supernatant and obtain precipitate I; wash precipitate I, dry it, and finally calcine it to obtain bismuth-rich bismuth vanadate nanosheets. II. Preparation of two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalysts: ① Disperse bismuth-rich bismuth vanadate nanosheets in an acid solution, heat and stir to obtain reaction product II; ② Centrifuge reaction product II to remove the supernatant and obtain precipitate II; The precipitate II was washed and then dried to obtain dried precipitate II. ③ Add the polymer and organic solvent to deionized water to form a uniform and stable solution C. Disperse the dried precipitate II into solution C and continue stirring to obtain a suspension. ④ Transfer the suspension to a high-pressure reactor and then perform a hydrothermal reaction at 120°C. Allow it to cool naturally to room temperature to obtain reaction product III. ⑤ Centrifuge the reaction product Ⅲ to remove the supernatant and obtain precipitate Ⅲ; wash precipitate Ⅲ, dry it, and finally calcine it to obtain a two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth vanadate photocatalyst.
2. The method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-vanadate photocatalyst according to claim 1, characterized in that... The bismuth source mentioned in step 1① is bismuth nitrate; the alcohol solvent mentioned in step 1① is ethylene glycol; and the surfactant mentioned in step 1① is hexadecyltrimethylammonium bromide.
3. The method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-vanadate photocatalyst according to claim 1, characterized in that... In step 1①, the mass-to-volume ratio of bismuth source, urea, and alcohol solvent in solution A is (2.425g~12.125g):(1.00g~5.00g):(35mL~175mL); in step 1①, the mass-to-volume ratio of surfactant to alcohol solvent in solution B is (1.00g~5.00g):(35mL~175mL).
4. The method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-vanadate photocatalyst according to claim 1, characterized in that... The mass ratio of ammonia metavanadate to the volume ratio of alcohol solvent in solution A in step 1① is (0.3g~1.5g):(35mL~175mL); the stirring speed in step 1① is 300r / min~500r / min.
5. The method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-vanadate photocatalyst according to claim 1, characterized in that... In step 1①, solution A and solution B are mixed, then ammonium metavanadate is added, the pH of the system is adjusted to 4~5, and stirring is continued for 20min~30min to obtain a suspension; the hydrothermal reaction time mentioned in step 1② is 20h~24h.
6. The method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-vanadate photocatalyst according to claim 1, characterized in that... In step 1, ③, the precipitate I is centrifuged and washed sequentially with deionized water and anhydrous ethanol at a speed of 3000 r / min to 4000 r / min, for a total of 10 to 15 times, with each centrifugation lasting 10 to 15 minutes. The drying temperature in step 1, ③ is 60℃ to 80℃, and the drying time is 12 to 24 hours. The calcination temperature in step 1, ③ is 400℃ to 450℃, and the calcination time is 8 to 12 minutes.
7. The method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-vanadate photocatalyst according to claim 1, characterized in that... The acid solution mentioned in step 2① is hydrochloric acid with a concentration of 0.036 g / L to 0.182 g / L; the heating and stirring temperature mentioned in step 2① is 40℃ to 50℃, the speed is 100 r / min to 300 r / min, and the time is 30 min to 40 min; the polymer mentioned in step 2③ is polyvinylpyrrolidone; the organic solvent mentioned in step 2③ is ethylene glycol.
8. The method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-vanadate photocatalyst according to claim 1, characterized in that... The mass-to-volume ratio of bismuth-rich bismuth vanadate nanosheets, polymer, organic solvent, and deionized water in step two is (0.1g~0.2g):(0.2g~0.4g):(0.05mL~0.2mL):(15mL~30mL); the washing in step two involves sequential centrifugation with deionized water and anhydrous ethanol at a speed of 3000r / min~4000r / min, for a total of 3~6 times, with each centrifugation lasting 5min~10min; the drying temperature in step two is 60℃~80℃, and the drying time is 12h~24h.
9. The method for preparing a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-vanadate photocatalyst according to claim 1, characterized in that... In step 2①, the mass ratio of bismuth-rich bismuth vanadate nanosheets to the volume ratio of the acid solution is (0.1g~0.2g):(20mL~40mL); in step 2③, the stirring time is 20min~30min; in step 2④, the hydrothermal reaction time is 3h~4h; in step 2⑤, the calcination temperature is 400℃~450℃, and the calcination time is 8min~12min.
10. The application of a two-dimensional sub-nanometer ortho-vanadium-oxygen dual-defect bismuth-vanadate photocatalyst prepared by the preparation method according to claim 1, characterized in that... A two-dimensional sub-nanometer ortho-vanadium-oxygen double-defect bismuth-rich vanadate photocatalyst is used as a photocatalyst for the desorption of oxygen from water.