A water-soluble BiO 2-x and its preparation method

Abstract

This invention relates to a water-soluble BiO 2‑x This invention relates to the field of nanomaterial chemistry and its preparation method, and belongs to the field of nanomaterial chemistry. It solves the problem of preparing BiO under high temperature and hydrothermal conditions using existing technologies. 2‑x The yield is low and the process is complex; the prepared BiO 2‑x The present invention addresses the problem of low catalytic activity. The water-soluble BiO₂ of this invention... 2‑x The molecular structure of BiO has oxygen vacancy defects. 2‑x The raw materials for its preparation include bismuth nitrate, alkali metal hydroxides, and oxidizing agents. BiO 2‑x It is in the form of nanosheets, with a length and width of 40-50 nm and a thickness of 9-12 nm.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial chemistry, and more particularly to a water-soluble BiO₂. 2-x And its preparation method. Background Technology

[0002] Photocatalysis is a process that uses light energy to excite photogenerated electrons and holes on the surface of a catalyst, thereby promoting a chemical reaction. Photocatalysis technology has broad application prospects in environmental protection, energy conversion, and organic synthesis.

[0003] BiO 2-x It is an excellent photocatalytic material. It possesses a narrow band gap and visible light response, effectively absorbing light within the visible light range. When BiO... 2-x When light energy is absorbed, excited electron-hole pairs are formed and participate in the catalytic reaction process. These electron-hole pairs can... 2-x Photoelectrochemical reactions occur on the surface of the substrate, thereby promoting the oxidation or reduction reaction of the substrate.

[0004] Currently, BiO 2-x Nanomaterials are mainly produced by breaking down large BiO blocks. 2-x Material preparation. Generally, hydrothermal and ultrasonic methods are used. Bulk BiO2 prepared by hydrothermal method. 2-x Two-dimensional BiO2 typically requires ultrasonic disruption. 2-x Nanosheets exhibit low yield, inconsistent morphology, and are prone to introducing impurities. Furthermore, the direct preparation of BiO2 via a hydrothermal method... 2-x Nanomaterial processing involves complex steps, requires high hydrothermal temperatures, and involves long reaction times, leading to the challenges of BiO2 production. 2-x Low yield. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a water-soluble BiO 2-x Its preparation method can solve at least one of the following technical problems: (1) Existing methods for preparing BiO under high temperature hydrothermal environment 2-x The yield is low and the steps are complicated; (2) the BiO prepared is low. 2-x Its catalytic activity is low.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a BiO 2-x The preparation method includes the following steps:

[0008] Step 1: Prepare a bismuth salt solution;

[0009] Step 2: Prepare an alkaline reagent by adding an oxidizing agent to the alkaline reagent to obtain an alkaline-oxidizing agent mixed solution;

[0010] Step 3: After atomizing the bismuth salt solution, add it to the alkali-oxidant mixed solution to obtain the reaction solution;

[0011] Step 4: Increase the temperature to carry out the hydrothermal reaction;

[0012] Step 5: Centrifuge the solution after the reaction to obtain water-soluble BiO. 2-x ;

[0013] The value of x ranges from 0.08 to 0.16.

[0014] Optionally, in step 3, an atomizer is used to atomize the bismuth salt solution.

[0015] Optionally, step 1 includes the following steps:

[0016] Step a: Dissolve bismuth nitrate pentahydrate in water to induce a hydrolysis reaction;

[0017] Step b: Add solvent to the hydrolysis solution from step a to completely dissolve bismuth nitrate into a solution, thus obtaining a bismuth salt solution.

[0018] Optionally, in step a, the concentration of bismuth nitrate pentahydrate is 80%-99%.

[0019] Optionally, in step 5, the centrifugation speed is 5000-8000 r / min.

[0020] Optionally, in step 3, the pH of the reaction solution is 12-14.

[0021] Secondly, the present invention provides a water-soluble BiO 2-x The BiO was prepared using the above-described preparation method. 2-x The molecular structure of BiO has oxygen vacancy defects. 2-x The raw materials for preparation include bismuth nitrate, alkali metal hydroxides, and oxidizing agents; the BiO 2-x It is in the form of nanosheets, with a length and width of 40-50 nm and a thickness of 9-12 nm.

[0022] Optionally, the value of x is 0.08 to 0.16.

[0023] Optionally, the oxidant is hypochlorite or chlorine.

[0024] Thirdly, the present invention also provides a water-soluble BiO2 prepared by the above-described preparation method. 2-x Or the above-mentioned water-soluble BiO 2-x Applications of photocatalysts in environmental protection, energy conversion, and organic synthesis.

[0025] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0026] (1) This invention employs atomization dispersion technology to control the particle size of the bismuth nitrate solution. After adding the reaction solution, on the one hand, it reduces the hydrolysis reaction of bismuth nitrate in water, and on the other hand, it limits the reaction rate of bismuth nitrate, thereby reducing the product particle size and thus lowering the hydrothermal conditions. Specifically, existing sheet-like BiO 2-x The size is several hundred nanometers, while the sheet-like BiO of this invention... 2-x The size is 40-50 nm. The existing hydrothermal reaction temperature is 150-180℃ and the time is 5-8h, while the hydrothermal reaction temperature of this invention is only 50-90℃ and the hydrothermal reaction time is only 0.2-2h.

[0027] (2) Existing BiO technology 2-x Nanosheets are insoluble in water, resulting in a small contact area and low catalytic efficiency when reacting with other substances in water. BiO2 prepared using the method of this invention... 2-x Nanosheets are soluble in water, and when they react with other substances in water, they have a larger contact area, which improves their catalytic adsorption capacity and catalytic efficiency.

[0028] (3) BiO prepared by the method of the present invention 2-x The band gap is 0.7-0.9 eV, proving that BiO 2-x With a wider spectral absorption range, on the one hand, it can use radiation with lower intensity to kill cancer cells, thereby reducing the damage of radiation to normal human cells and achieving the effect of radiotherapy; on the other hand, because it has a wider spectral absorption range, it can improve photocatalytic efficiency.

[0029] (4) BiO prepared by the method of the present invention 2-x Its small size (length and width only 40-50 nm) results in a large specific surface area and strong adsorption capacity. Specifically, the BiO of this invention... 2-x Its ability to adsorb pollutants is 4 to 5 times that of existing technologies.

[0030] (5) BiO prepared by the method of the present invention 2-x The zeta potential remained around -50mV, proving that BiO 2-x It exhibits good stability in water, BiO 2-x Even when the concentration is increased to 30 mg / ml, it still maintains good stability.

[0031] (6) Compared with the existing hydrothermal method + ultrasonic fragmentation method, the atomization method + hydrothermal method of this invention enables the preparation of nano-BiO 2-x Yield will increase by at least 10%.

[0032] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages will become apparent from the description or may be learned by practicing the invention. Attached Figure Description

[0033] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0034] Figure 1 BiO2 prepared for Comparative Example 1 2-x TEM image;

[0035] Figure 2 BiO2 prepared for Comparative Example 2 2-x TEM image;

[0036] Figure 3 BiO prepared in Example 1 of this invention 2-x TEM image;

[0037] Figure 4 BiO prepared in Example 1 of this invention 2-x XPS plot;

[0038] Figure 5 Water-soluble BiO prepared in Example 1 of this invention 2-x Graph of zeta potential changes;

[0039] Figure 6 The water-soluble BiO in Example 1 of this invention 2-x The ultraviolet diffuse reflectance curve.

[0040] Figure 7 The water-soluble BiO in Example 1 of this invention 2-x The Tauc curve.

[0041] Figure 8 The water-soluble BiO prepared in Example 1 of this invention 2-x Concentration change curve of degrading Rhodamine B (RhB). Detailed Implementation

[0042] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0043] In a first aspect, the present invention also provides a BiO 2-x The preparation method includes the following steps:

[0044] Step 1: Prepare a bismuth salt solution;

[0045] Step 2: Prepare an alkaline reagent by adding an oxidizing agent to the alkaline reagent to obtain a mixed solution;

[0046] Step 3: Atomize the bismuth salt solution and add it to the mixed solution, stir, and obtain the reaction solution;

[0047] Step 4: Increase the temperature to carry out the hydrothermal reaction;

[0048] Step 5: Centrifuge the solution after the reaction to obtain water-soluble BiO. 2-x .

[0049] Specifically, in step 3, the bismuth salt solution is atomized using an atomizer. The atomization rate is 0.01-1 mL / s, and the diameter of the atomized bismuth salt droplets is 1-200 μm.

[0050] Specifically, step 1 includes the following steps:

[0051] Step a: Dissolve bismuth nitrate pentahydrate in water to induce a hydrolysis reaction;

[0052] Step b: Add solvent to the hydrolysis solution from step a to completely dissolve bismuth nitrate into a solution, thus obtaining a bismuth salt solution.

[0053] Specifically, in step a, the concentration of bismuth nitrate pentahydrate is 80%-99%.

[0054] In one embodiment, the solvent in step b is concentrated hydrochloric acid or concentrated nitric acid, or it can be ethylene glycol, acetone, etc. The amount of solvent added (mL) is 1.5-3 times the mass (g) of bismuth nitrate pentahydrate.

[0055] Specifically, in step 5, the centrifugation speed is 5000-8000 r / min.

[0056] Specifically, in step 3, the pH of the reaction solution is 12-14.

[0057] Specifically, in step 4, the hydrothermal reaction temperature is 50-90℃, for example, 50℃, 60℃, 70℃, 80℃, or 90℃. The hydrothermal reaction time is 0.2-2 hours, for example, 0.2 hours, 0.3 hours, 0.4 hours, 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, 1.0 hour, 1.3 hours, 1.5 hours, 1.8 hours, or 2 hours.

[0058] This invention employs atomization dispersion technology to control the particle size of the bismuth nitrate solution. After adding the reaction solution, it reduces the hydrolysis reaction of bismuth nitrate in water and limits the reaction rate, thereby reducing the product particle size and lowering hydrothermal requirements. Specifically, existing sheet-like BiO₂... 2-x The size is several hundred nanometers, while the sheet-like BiO of this invention... 2-x The size is 40-50 nm. The existing hydrothermal reaction temperature is 150-180℃ and the time is 5-8h, while the hydrothermal reaction temperature of this invention is only 50-90℃ and the hydrothermal reaction time is only 0.2-2h.

[0059] BiO prepared by the method of the present invention 2-x Nanosheets are soluble in water, and when they react with other substances in water, they have a larger contact area, which improves their catalytic adsorption capacity and catalytic efficiency.

[0060] Secondly, the present invention also provides a water-soluble BiO 2-x The material was prepared using the method described above. The value of x is 0.08–0.16, for example, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, or 0.16, preferably 0.08–0.14. This water-soluble BiO 2-x It is in the form of nanosheets, specifically, approximately square sheets, with a length and width of 40-50 nm and a thickness of 9-12 nm.

[0061] Specifically, the BiO of the present invention 2-x The band gap is 0.7-0.9 eV, proving that BiO 2-x With a wider spectral absorption range, on the one hand, it can use radiation with lower intensity to kill cancer cells, thereby reducing the damage of radiation to normal human cells and achieving the effect of radiotherapy; on the other hand, because it has a wider spectral absorption range, it can improve photocatalytic efficiency.

[0062] Furthermore, due to the BiO of the present invention 2-x Nanosheets are small in size (only 40-50 nm in length and width), therefore, they have a large specific surface area and strong adsorption capacity. Specifically, the BiO of this invention... 2-x Its ability to adsorb pollutants is 4 to 5 times that of existing technologies.

[0063] BiO of existing technology 2-x Nanosheets are insoluble in water, resulting in a small contact area and low catalytic efficiency when reacting with other substances in water. The BiO of this invention... 2-x Nanosheets are soluble in water, and when they react with other substances in water, they have a larger contact area, which improves their catalytic adsorption capacity and catalytic efficiency.

[0064] Specifically, the BiO of the present invention 2-x The zeta potential remained around -50mV, proving that BiO 2-x It exhibits good stability in water, BiO 2-x Even when the concentration is increased to 30 mg / ml, it still maintains good stability.

[0065] Example 1

[0066] Step 1: Prepare bismuth salt solution: Take 2g of Bi(NO3)3·5H2O (molecular weight 487.5) powder with a purity of 99.9% and add it to 10mL of water. Sonicate the solution and add 4ml of concentrated hydrochloric acid to completely dissolve the bismuth nitrate to form a solution.

[0067] Step 2: Prepare an alkali-oxidant mixed solution: Take 20g of 96% pure NaOH (molecular weight 40) powder and add it to 500mL of water to dissolve by sonication. Then weigh 0.5g of NaClO (available chlorine ≥60%) powder and add it to the solution. Stir and dissolve to prepare a sodium hydroxide-sodium hypochlorite mixed solution.

[0068] Step 3: Place the beaker containing the sodium hydroxide-sodium hypochlorite mixed solution on the stirring table. Use an atomizer to convert the bismuth salt solution into small droplets and transfer them to the sodium hydroxide-sodium hypochlorite mixed solution. Adjust the pH of the solution to approximately 14, and continue stirring for 30 minutes to form a stable suspension (reaction solution).

[0069] Step 4: Transfer the suspension to a 2L polytetrafluoroethylene reactor for hydrothermal reaction at 50°C for 2 hours, then cool to room temperature.

[0070] Step 5: Discard the supernatant, centrifuge the precipitate, and take the supernatant at 5000 rpm. Dry it at 80°C to obtain water-soluble BiO. 2-x The value of x is 0.08.

[0071] Example 2

[0072] Step 1: Prepare bismuth salt solution: Take 2g of Bi(NO3)3·5H2O powder with a purity of 99.9% and add it to 10mL of water. Sonicate the solution and add 4ml of concentrated nitric acid to completely dissolve the bismuth nitrate to form a solution.

[0073] Step 2: Prepare an alkali-oxidant mixed solution: Take 20g of 96% pure NaOH (molecular weight 40) powder and add it to 500mL of water to dissolve by sonication. Then weigh 0.5g of NaClO (available chlorine ≥60%) powder and add it to the solution. Stir and dissolve to prepare a sodium hydroxide-sodium hypochlorite mixed solution.

[0074] Step 3: Place the beaker containing the sodium hydroxide-sodium hypochlorite mixed solution on the stirring table. Use an atomizer to convert the bismuth salt solution into small droplets and transfer them to the sodium hydroxide-sodium hypochlorite mixed solution. Adjust the pH of the solution to approximately 14, and continue stirring for 30 minutes to form a stable suspension (reaction solution).

[0075] Step 4: Transfer the suspension to a 2L polytetrafluoroethylene reactor for hydrothermal reaction at 90℃ for 0.2h, then cool to room temperature.

[0076] Step 5: Discard the supernatant, centrifuge the precipitate, and take the supernatant at 8000 rpm. Dry it at 80°C to obtain water-soluble BiO. 2-x The value of x is 0.16.

[0077] Example 3

[0078] Step 1: Prepare bismuth salt solution: Take 2g of Bi(NO3)3·5H2O (molecular weight 487.5) powder with a purity of 99.9% and add it to 10mL of water. Sonicate the solution and add 4ml of concentrated hydrochloric acid to completely dissolve the bismuth nitrate to form a solution.

[0079] Step 2: Prepare an alkali-oxidant mixed solution: Take 20g of 96% pure NaOH (molecular weight 40) powder and add it to 500mL of water to dissolve by sonication. Then weigh 0.5g of NaClO (available chlorine ≥60%) powder and add it to the solution. Stir and dissolve to prepare a sodium hydroxide-sodium hypochlorite mixed solution.

[0080] Step 3: Place the beaker containing the sodium hydroxide-sodium hypochlorite mixed solution on the stirring table. Use an atomizer to convert the bismuth salt solution into small droplets and transfer them to the sodium hydroxide-sodium hypochlorite mixed solution. Adjust the pH of the solution to approximately 14, and continue stirring for 30 minutes to form a stable suspension (reaction solution).

[0081] Step 4: Transfer the suspension to a 2L polytetrafluoroethylene reactor for hydrothermal reaction at 70℃ for 1 hour, then cool to room temperature.

[0082] Step 5: Discard the supernatant, centrifuge the precipitate, and take the supernatant at 6000 rpm. Dry it at 80°C to obtain water-soluble BiO. 2-x The value of x is 0.12.

[0083] Comparative Example 1

[0084] The comparative example is basically the same as Example 1, except that the atomization dispersion technology was not used. Instead, a pipette was used to dropwise add the bismuth salt solution into the sodium hydroxide-sodium hypochlorite mixed solution.

[0085] Comparative Example 2

[0086] The comparative example is basically the same as Example 1, except that concentrated acid was not used to dissolve Bi(NO3)3·5H2O.

[0087] The products obtained from Comparative Example 1, Comparative Example 2, and Example 1 were subjected to electron microscopy, and the results are shown in the figures below. Figure 1 , Figure 2 and Figure 3 .

[0088] Figure 1 and Figure 2 BiO 2-x There is a clear clustering phenomenon, and Figure 3 The absence of obvious clustering indicates that the present invention employs atomization dispersion technology and BiO2 obtained by dissolving Bi(NO3)3·5H2O in concentrated acid. 2-x BiO₂ is not easily aggregated, and is obtained without atomization dispersion technology or without dissolving Bi(NO₃)₃·5H₂O with concentrated acid. 2-x Easy to reunite.

[0089] In addition, by Figure 4 X-ray photoelectron spectroscopy data show that the BiO prepared in this invention... 2-x It contains numerous defects.

[0090] Furthermore, the present invention also applies to the BiO prepared in Example 1. 2-x The following tests and characterizations were performed:

[0091] (1) The stability in water was characterized by using DLS to test the water solubility of BiO. 2-x Changes in zeta potential in water, such as Figure 5 As shown.

[0092] (2) BiO was measured 2-x The ultraviolet diffuse reflectance curve of nanomaterials is as follows Figure 6 As shown, the band gap is calculated as follows: Figure 7 As shown, the magnitude of the excitation current under visible light was tested.

[0093] (3) The prepared BiO 2-x Photocatalytic pollutant experiments were conducted, using Rhodamine B as a simulated pollutant for degradation experiments. Changes in pollutant concentration were measured using a UV-Vis spectrophotometer. Figure 8 As shown.

[0094] 1. Prepare 50ml of 500ppm BiO3 solution. 2-x A mixed solution of 10 ppm RhB.

[0095] 2. Stir the solution in the dark and measure the initial RhB concentration. After 30 minutes, measure the RhB concentration in the solution again.

[0096] 3. Irradiate the solution under a xenon lamp for 30 minutes and measure the RhB concentration.

[0097] Depend on Figure 5 It can be seen that the BiO prepared by this invention 2-x The zeta potential is maintained at around -50mV, indicating that it has good stability in water.

[0098] Depend on Figure 6 As can be seen from the ultraviolet diffuse reflectance test, the nano-BiO synthesized in Example 1... 2-x Nano-BiO exhibits higher absorbance in the visible light range, and even in the infrared range. 2-x It also exhibits high absorbance.

[0099] Depend on Figure 7 It can be seen that the existing BiO technology 2-x The band gap of the BiO synthesized in this invention is 1.60 eV. 2-x The band gap is 0.78 eV, proving that BiO 2-x With a wider spectral absorption range, on the one hand, it can use radiation with lower intensity to kill cancer cells, thereby reducing the damage of radiation to normal human cells and achieving the effect of radiotherapy; on the other hand, because it has a wider spectral absorption range, it can improve photocatalytic efficiency.

[0100] Depend on Figure 8 It can be seen that, during the degradation of Rhodamine B, existing BiO 2-x The catalytic adsorption performance exhibited in the visible light range is very weak; the nano-BiO synthesized in Example 1 2-x It exhibits extremely high catalytic adsorption capacity in both light- and dark environments.

[0101] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A BiO 2-x The preparation method of the [method] is characterized by, Includes the following steps: Step 1: Prepare a bismuth salt solution; Step 2: Prepare an alkaline reagent by adding an oxidizing agent to the alkaline reagent to obtain an alkaline-oxidizing agent mixed solution; Step 3: After atomizing the bismuth salt solution, add it to the alkali-oxidant mixed solution to obtain the reaction solution; Step 4: Increase the temperature to carry out the hydrothermal reaction; Step 5: Centrifuge the solution after the reaction to obtain water-soluble flake-like BiO. 2-x ; Where x ranges from 0.08 to 0.16; In step 4, the hydrothermal reaction temperature is 50-90℃, and the hydrothermal reaction time is 0.2-2h; Step 1 includes the following steps: Step a: Dissolve bismuth nitrate pentahydrate in water to induce a hydrolysis reaction; Step b: Add solvent to the hydrolysis solution from step a to completely dissolve bismuth nitrate into a solution, thus obtaining a bismuth salt solution; Flaky BiO 2-x The length and width are 40-50 nm, the thickness is 9-12 nm, and the band gap is 0.7-0.9 eV.

2. The preparation method according to claim 1, characterized in that, In step 3, an atomizer is used to atomize the bismuth salt solution.

3. The preparation method according to claim 1, characterized in that, In step 5, the centrifugation speed is 5000-8000 r / min.

4. The preparation method according to any one of claims 1-3, characterized in that, In step 3, the pH of the reaction solution is 12-14.

5. A water-soluble BiO 2-x Its characteristics are, The BiO was prepared by the preparation method according to any one of claims 1-4. 2-x The molecular structure of BiO has oxygen vacancy defects. 2-x The raw materials for its preparation include bismuth nitrate, alkali metal hydroxides, and oxidizing agents; The BiO 2-x It is in the form of nanosheets, with a length and width of 40-50 nm and a thickness of 9-12 nm.

6. The water-soluble BiO according to claim 5 2-x Its characteristics are, The value of x ranges from 0.08 to 0.

16.

7. The water-soluble BiO according to claim 5 2-x Its characteristics are, The oxidant is hypochlorite or chlorine.

8. A water-soluble BiO2 prepared by the method according to any one of claims 1-4 2-x Or the water-soluble BiO as described in any one of claims 5-7 2-x Applications of photocatalysts in environmental protection, energy conversion, and organic synthesis.

Images