A tungsten oxide photocatalyst selectively producing singlet oxygen and a preparation method and application thereof

Abstract

The application discloses a tungsten oxide photocatalyst capable of selectively generating singlet oxygen and a preparation method and application thereof, and the preparation method comprises the following steps: S1, uniformly mixing a small molecule regulator, ethanol and water to obtain a mixed solution; S2, adding a tungsten element compound into the mixed solution to stir and dissolve, obtaining a yellow solution, and then adding the small molecule regulator until the solution turns blue; S3, placing the blue solution obtained in S2 into a hydrothermal reaction device to react, and after the reaction is completed, washing and drying the solid to obtain the tungsten oxide photocatalyst capable of selectively generating singlet oxygen. The tungsten oxide photocatalyst provided by the application can degrade various organic pollutants, and has the advantages of simple preparation method, low cost, macro-preparation, and suitability for industrial production and the like. The prepared tungsten oxide photocatalyst can be applied to the field of photocatalytic degradation of organic pollutants and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials, in particular to a tungsten oxide photocatalyst selectively generating singlet oxygen and a preparation method and application thereof. BACKGROUND

[0002] Water pollution is threatening human beings and attracting more and more attention worldwide. Photochemical reactions widely exist in water environment and play an important role in aquatic ecosystems. Solar energy-induced photodegradation is effective for many organic micro-pollutants, especially those that cannot be hydrolyzed or biodegraded, thereby reducing chemical pollution. Therefore, photocatalysis utilizes inexhaustible solar energy to achieve degradation of organic pollutants, which is one of the effective ways to solve environmental problems.

[0003] Metal oxides are promising photocatalysts, and their lattice matrix can be modified by defect engineering to produce multiple synergistic effects on photocatalytic processes in terms of charge dynamics and molecular chemical adsorption. The defect band of the oxide can serve as a reservoir for photo-generated electrons, thereby reducing unfavorable charge recombination. At the same time, surface defects make the metal center in a coordination unsaturated state, providing suitable sites for molecular chemical adsorption and establishing an effective channel for electron interaction. Among various metal oxide photocatalysts, tungsten oxide is a strong candidate for rational construction of surface structure. Therefore, tungsten oxide materials with surface structure have been widely used in photocatalytic reactions and shown great potential.

[0004] Singlet oxygen is an excellent reactive oxygen species for selective conversion of organic matter, especially in advanced oxidation processes. However, due to the great difficulty in synthesizing selective catalysts, it is still challenging to control and regulate the generation of singlet oxygen in advanced oxidation processes, and the underlying mechanism is still unclear.

[0005] In recent years, the construction of stable systems based on small molecule surface regulation has opened up a new method for modifying nanomaterials and broadened the potential applications of surface-modified nanomaterials in the field of catalysis.

[0006] Chinese patent application document with publication number CN115583670A discloses a sea urchin-shaped or rod-shaped tungsten oxide and a preparation method and application thereof. WCl6 black solid powder is dissolved in ethanol or cyclohexanol, and then ultrasonic immersion is performed after mixing and stirring. After the WCl6 black solid powder is completely dissolved in ethanol or cyclohexanol, ultrasonic immersion is continued. When the solution changes from yellow to dark blue, the solution is immediately transferred to a stainless steel reaction kettle with polytetrafluoroethylene as the inner liner. Then, the reaction kettle is placed in a forced air drying oven at 100-200℃ for 24h of solvothermal treatment. After cooling to room temperature, the sea urchin-shaped tungsten oxide W 18 O49 or rod-like tungsten oxide WO3, urchin-like tungsten oxide WO3 18 O 49 or rod-like tungsten oxide WO3, urchin-like tungsten oxide WO3 SUMMARY

[0007] The technical problem to be solved by the present application is how to obtain a tungsten oxide photocatalyst capable of selectively producing singlet oxygen.

[0008] The present application solves the above technical problems by the following technical means:

[0009] A preparation method of a tungsten oxide photocatalyst capable of selectively producing singlet oxygen, comprising the following steps:

[0010] S1, uniformly mixing a small molecule regulator, ethanol and water to obtain a mixed solution;

[0011] S2, adding a tungsten element compound to the mixed solution and stirring to dissolve, to obtain a yellow solution, and then adding the small molecule regulator until the solution turns blue;

[0012] S3, placing the blue solution obtained in S2 in a hydrothermal reaction device for reaction, and after the reaction is completed, washing and drying the solid to obtain the tungsten oxide photocatalyst capable of selectively producing singlet oxygen.

[0013] Preferably, in S1, the small molecule regulator is a mixture of one or more of formic acid, oxalic acid, isopropanol, ethylene glycol, ethyl acetate, polyethylene glycol, dodecyltrimethylammonium bromide, polyvinylpyrrolidone and polyvinyl alcohol.

[0014] Preferably, in S1, the small molecule regulator is a mixture of one or more of formic acid, oxalic acid, isopropanol, ethylene glycol, polyethylene glycol, dodecyltrimethylammonium bromide, polyvinylpyrrolidone and polyvinyl alcohol.

[0015] Preferably, in S1, the volume ratio of the ethanol to water is 0.1-10:1; and the total volume ratio of the small molecule regulator, ethanol and water is ≤10g:100mL.

[0016] Preferably, in S1, the volume ratio of the ethanol to water is 0.1-5:1, further preferably 0.18-0.25:1, and more preferably 0.2:1.

[0017] Preferably, in S1, the mass ratio of the small molecule regulator, ethanol and water is ≤5g:100mL; preferably 0.13-0.27g:100mL, more preferably 0.25g:100mL.

[0018] Preferably, in S2, the tungsten element compound is selected from a mixture of one or more of tungsten chloride, tungstic acid, sodium tungstate, ammonium tungstate, and tungsten ethoxide.

[0019] Preferably, in S2, the tungsten element compound is selected from a mixture of one or more of tungsten chloride, tungstic acid, sodium tungstate, ammonium tungstate, and tungsten ethoxide.

[0020] Preferably, in S2, the small molecule regulator is added in multiple times until the solution turns blue.

[0021] Preferably, in S2, the mass of the tungsten element compound added per 100ml of mixed solution is ≤10g.

[0022] Preferably, the mass ratio of the small molecule regulator and the tungsten element compound is 0.05-0.12:0.18-0.3.

[0023] Preferably, in S2, the mass of the tungsten element compound added per 100ml of mixed solution is ≤8g, preferably 0.55g.

[0024] Preferably, in S3, the temperature of the reaction is 60-200℃, and the time is 1-72h.

[0025] Preferably, in S3, the temperature of the reaction is 100-200℃, specifically 120℃, 140℃, 150℃ or 180℃; and the time is 3-48h, specifically 12h.

[0026] Preferably, in S3, the washing includes centrifugal washing with deionized water and ethanol in sequence; and the drying temperature is 40-80℃, and the time is 1-24h.

[0027] Preferably, in S3, the drying temperature is 40-60℃; and the drying time is 1-12h, specifically 3h.

[0028] The application also provides a tungsten oxide photocatalyst for selectively generating singlet oxygen, which is prepared by the preparation method of the tungsten oxide photocatalyst for selectively generating singlet oxygen.

[0029] The application also provides an application of the tungsten oxide photocatalyst for selectively generating singlet oxygen in photocatalytic degradation of organic pollutants.

[0030] Preferably, the organic pollutants are chloroquine phosphate or norfloxacin or rhodamine B.

[0031] The present application has the advantages of:

[0032] The tungsten oxide photocatalyst provided by the present application can realize effective regulation of the surface of the catalyst by using a simple small molecule regulator during preparation of the material, without the need for other complex processing procedures. Meanwhile, the tungsten oxide photocatalyst can selectively generate singlet oxygen during photocatalytic degradation of organic pollutants. Singlet oxygen is an excellent active oxygen species for organic degradation reactions, and therefore the tungsten oxide photocatalyst provided by the present application has good catalytic effect.

[0033] The tungsten oxide photocatalyst provided by the present application can degrade various organic pollutants, and has the advantages of simple preparation method, low cost, and macro-preparation, and is suitable for industrial production and the like. The prepared tungsten oxide photocatalyst can be used in the field of photocatalytic degradation of organic pollutants and the like. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 X-ray diffraction pattern of the tungsten oxide photocatalyst provided for Example 1 of the present application;

[0035] Figure 2 Electron paramagnetic resonance spectrum of singlet oxygen generated by the tungsten oxide photocatalyst provided for Example 1 of the present application;

[0036] Figure 3 Photocurrent graph of the tungsten oxide photocatalyst provided for Example 1 of the present application;

[0037] Figure 4 Effect graph of degradation of chloroquine phosphate by the tungsten oxide photocatalyst provided for Example 1 of the present application;

[0038] Figure 5 Effect graph of degradation of norfloxacin by the tungsten oxide photocatalyst provided for Example 2 of the present application;

[0039] Figure 6 Effect graph of degradation of rhodamine B by the tungsten oxide photocatalyst provided for Example 3 of the present application

[0040] Figure 7 X-ray diffraction pattern of tungsten oxide provided for Comparative Example 1 of the present application;

[0041] Figure 8 Electron paramagnetic resonance spectrum of singlet oxygen generated by tungsten oxide provided for Comparative Example 1 of the present application;

[0042] Figure 9 Photocurrent graph of tungsten oxide provided for Comparative Example 1 of the present application;

[0043] Figure 10 Effect graph of degradation of chloroquine phosphate by tungsten oxide provided for Comparative Example 1 of the present application;

[0044] Figure 11 Figure of effect of tungsten oxide provided for Invention Comparative Example 2 on degradation of norfloxacin;

[0045] Figure 12 Figure of comparison of electron paramagnetic resonance spectra of tungsten oxide provided for Invention Example 1 and Comparative Example 1 on generation of singlet oxygen. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the protection scope of the present application.

[0047] The test materials and reagents used in the following examples, and the like, can be obtained from commercial channels if not otherwise specified.

[0048] The specific techniques or conditions not specified in the examples can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0049] Example 1

[0050] A preparation method of a tungsten oxide photocatalyst selectively generating singlet oxygen, comprising the following steps:

[0051] 0.05 g of isopropyl alcohol, 6 mL of ethanol and 30 mL of deionized water were measured and placed in a beaker with a capacity of 50 mL to be stirred uniformly to obtain a mixed solution; 0.18 g of tungsten chloride was weighed and added to the mixed solution, and stirred with a magnetic stirrer for 15 minutes until fully dissolved; at this time, the solution color was yellow, and isopropyl alcohol was added dropwise to the solution until the mixed solution changed from yellow to blue; the above blue mixed solution was transferred to a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene liner with a capacity of 50 mL, which was placed in a constant temperature drying box, and the reaction temperature was set to 150 ℃, and the reaction was carried out for 12 h; the reaction product was sequentially washed with deionized water and ethanol by centrifugation for 3 times, and the obtained solid product was dried in a constant temperature drying box at 80 ℃ for 3 h to obtain a tungsten oxide sample.

[0052] The obtained sample was detected by an X-ray diffractometer (instrument model: Philips X'Pert PRO SUPER), and an X-ray diffraction spectrum of Figure 1 was obtained, and it was determined that the sample was tungsten oxide WO3.

[0053] The obtained sample was detected by an electron paramagnetic resonance spectrometer (instrument model: JES-FA200 (JEOL)), and an electron paramagnetic resonance spectrum of Figure 2 was obtained, and it was determined that the sample generated singlet oxygen;

[0054] The obtained sample was detected by a photoelectrochemical test system (composed of a CHI600E electrochemical workstation + CEL-HXF300-T3 photocatalytic xenon lamp light source, and during the test, the light-on / light-off control was realized by periodically interrupting the opening and closing of the xenon lamp light source, and the I-T test mode of the electrochemical workstation was used to detect the current-time curve), and a Figure 3 photocurrent diagram was obtained, and it was determined that the sample had good photoelectric performance;

[0055] The sample obtained in Example 1 was used as a catalyst, and the performance of the sample in catalytic degradation of chloroquine phosphate was detected. During the detection, 5 mg of the catalyst was mixed with 40.0 mL of chloroquine phosphate aqueous solution with an initial concentration of 30.0 mg / L to obtain a mixed solution, and two portions of the mixed solution with the same configuration were placed in darkness and under LED visible light (the visible light source was 300W), respectively. Every 5 minutes, 3 ml of the solution was taken for filtration. The filtrate was measured by a UV-visible spectrometer to obtain the residual chloroquine phosphate concentration, and a Figure 4 degradation effect diagram of chloroquine phosphate was obtained, and it can be seen from Figure 4 that the initial concentration of chloroquine phosphate was 30 mg / L, and after 60 minutes of photocatalytic reaction, the concentration of chloroquine phosphate was reduced to less than 5 mg / L, and the degradation effect was good.

[0056] Example 2

[0057] A preparation method of a tungsten oxide photocatalyst selectively generating singlet oxygen, comprising the following steps:

[0058] 0.12 g of dodecyltrimethylammonium bromide, 15 mL of ethanol and 60 mL of deionized water were measured and placed in a beaker with a capacity of 100 mL and stirred uniformly to obtain a mixed solution; 0.3 g of ammonium tungstate was weighed and added to the mixed solution, and stirred with a magnetic stirrer for 15 minutes until completely dissolved; at this time, the color of the solution was yellow, and dodecyltrimethylammonium bromide was added dropwise to the solution until the mixed solution changed from yellow to blue; the blue mixed solution was transferred to a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene liner with a capacity of 100 mL, and was placed in a constant temperature drying box, and the reaction temperature was set to 120℃, and the reaction was carried out for 10 h; the reaction product was sequentially washed with deionized water and ethanol by centrifugation for 3 times, and the obtained solid product was dried in a constant temperature drying box at 70℃ for 5 h to obtain a tungsten oxide sample.

[0059] The obtained sample was subjected to the same identification and detection analysis as in Example 1, and the XRD diffraction pattern, electron paramagnetic resonance spectrum and photocurrent diagram thereof were similar to those of the product of Example 1, which determined that the obtained tungsten oxide photocatalyst could selectively generate singlet oxygen and had good photoelectric performance.

[0060] The sample obtained in Example 2 was used as a catalyst to detect the performance of degrading norfloxacin according to the performance detection process of catalytic degradation of chloroquine phosphate in Example 1, and the performance detection process of degrading norfloxacin was obtained as follows. Figure 5 The degradation effect diagram of norfloxacin is shown in Figure 2. Figure 5 It can be seen that the initial concentration of norfloxacin is 10 mg / L, and after 60 minutes of photocatalytic reaction, the concentration of norfloxacin is reduced to less than 1 mg / L, and the degradation effect is good.

[0061] Example 3

[0062] A preparation method of a tungsten oxide photocatalyst for selectively generating singlet oxygen, comprising the following steps:

[0063] 0.1 g of polyvinyl alcohol (polyvinyl alcohol 1750±50), 6 mL of ethanol and 32 mL of deionized water were measured and stirred uniformly in a beaker with a capacity of 50 mL to obtain a mixed solution; 0.2 g of sodium tungstate was weighed and added to the above mixed solution, and stirred with a magnetic stirrer for 15 minutes until completely dissolved; at this time, the color of the solution is yellow, and the above polyvinyl alcohol is added dropwise to the solution until the mixed solution changes from yellow to blue; the above blue mixed solution is transferred to a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene inner liner with a capacity of 50 mL, which is placed in a constant temperature drying box, and the reaction temperature is set to 180℃, and the reaction is carried out for 8h; the reaction product is sequentially washed with deionized water and ethanol by centrifugation for 3 times, and the obtained solid product is dried in a constant temperature drying box at 60℃ for 8h to obtain a tungsten oxide sample.

[0064] The obtained sample was subjected to the same identification and detection analysis as in Example 1, and the XRD diffraction pattern, electron paramagnetic resonance spectrum, and photocurrent diagram thereof were similar to those of the product of Example 1, which determined that the obtained tungsten oxide photocatalyst could selectively generate singlet oxygen and had good photoelectric performance.

[0065] The sample obtained in Example 3 was used as a catalyst to detect the performance of degrading rhodamine B according to the performance detection process of catalytic degradation of chloroquine phosphate in Example 1, and the performance detection process of degrading rhodamine B was obtained as follows. Figure 6 The degradation effect diagram of rhodamine B is shown in Figure 3. Figure 6 It can be seen that the initial concentration of rhodamine B is 20 mg / L, and after 60 minutes of photocatalytic reaction, the concentration of rhodamine B is reduced to less than 5 mg / L, and the degradation effect is good.

[0066] Comparative Example 1

[0067] Take 0.05 g of isopropyl alcohol, 6 mL of ethanol and 30 mL of deionized water, stir uniformly in a beaker with a capacity of 50 mL to obtain a mixed solution; weigh 0.18 g of tungsten chloride, add it to the above mixed solution, and stir with a magnetic stirrer for 15 minutes to obtain a reaction solution; transfer the above reaction solution to a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene liner with a capacity of 50 mL, place it in a constant temperature drying box, set the reaction temperature to 150℃, and react for 12 h; centrifugally wash the reaction product with deionized water and ethanol for 3 times respectively, dry the obtained solid product in a constant temperature drying box at 80℃ for 3 h, and obtain a tungsten oxide sample.

[0068] The obtained sample was detected by an X-ray diffractometer (instrument model: Philips X'Pert PRO SUPER) to obtain an X-ray diffraction spectrum of Figure 7 , which determined that the sample was tungsten trioxide.

[0069] The obtained sample was detected by an electron paramagnetic resonance spectrometer (instrument model: JES-FA200 (JEOL)) to obtain an electron paramagnetic resonance spectrum of Figure 8 , which determined that the sample produced a small amount of singlet oxygen, and the comparison chart of the electron paramagnetic resonance spectrum of the sample and the sample of Example 1 is shown in Figure 12 .

[0070] The obtained sample was detected by a photoelectrochemical test system (composed of CHI600E electrochemical workstation + CEL-HXF300-T3 photocatalytic xenon lamp light source, in the test process, the light-on / light-off control was realized by periodically interrupting the opening and closing of the xenon lamp light source, and the current-time test mode of the electrochemical workstation was used to detect the current-time curve) to obtain a photocurrent graph of Figure 9 , which determined that the photoelectric performance of the sample was poor.

[0071] The sample obtained in Comparative Example 1 was used as a catalyst, and its performance for degrading chloroquine phosphate was detected according to the performance detection process for catalytic degradation of chloroquine phosphate in Example 1, and a degradation effect of chloroquine phosphate under light condition was obtained. Figure 10 As shown in Figure 10 , the degradation effect was poor.

[0072] Comparative Example 2

[0073] Take 0.12 g of dodecyl trimethyl ammonium bromide, 15 mL of ethanol and 60 mL of deionized water, place them in a beaker with a capacity of 100 mL, stir them uniformly to obtain a mixed solution; take 0.3 g of ammonium tungstate, add it to the mixed solution, stir it with a magnetic stirrer for 15 minutes until it is fully dissolved to obtain a reaction solution; transfer the reaction solution to a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene liner with a capacity of 100 mL, place it in a constant temperature drying box, set the reaction temperature to 120°C, and react for 10 hours; centrifugally wash the reaction product with deionized water and ethanol for 3 times respectively, dry the obtained solid product in a constant temperature drying box at 70°C for 5 hours to obtain a tungsten trioxide sample.

[0074] The obtained sample is subjected to the same identification and detection analysis as in the above Comparative Example 1, and its XRD diffraction pattern, electron paramagnetic resonance spectrum and photocurrent diagram are similar to those of the product of Comparative Example 1, and it is determined that the obtained tungsten oxide produces less singlet oxygen.

[0075] The sample obtained in Comparative Example 2 is used as a catalyst, and its performance in degrading norfloxacin is detected according to the performance detection process of catalytic degradation of chloroquine phosphate in Example 1, and the degradation effect is Figure 11 The degradation effect of norfloxacin under light conditions is shown in the figure, and Figure 11 It can be seen that the degradation effect is poor.

[0076] Comparative Example 3

[0077] The tungsten trioxide purchased from the National Pharmaceutical Group is used as a catalyst, and chloroquine phosphate, norfloxacin and rhodamine B are catalytically degraded according to the methods of Examples 1-3, and the degradation effect is poor, and singlet oxygen cannot be produced.

[0078] Comparative Example 4

[0079] The same synthesis scheme as in Example 1 is adopted, except that the small molecule regulator isopropyl alcohol is not added to the raw material, and the other reaction conditions are not changed. After detection, the product obtained is tungsten trioxide, but singlet oxygen is not produced. The photocatalytic degradation of chloroquine phosphate, norfloxacin and rhodamine B has little catalytic effect.

[0080] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent substitutions for part of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for producing a tungsten oxide photocatalyst selectively generating singlet oxygen, characterized by: The method comprises the following steps: S1, mixing a small molecule regulator, ethanol and water to obtain a mixed solution; The small molecule regulator is a mixture of one or more of isopropyl alcohol, dodecyl trimethyl ammonium bromide and polyvinyl alcohol; S2, adding a tungsten source compound to the mixed solution and stirring to dissolve, to obtain a yellow solution, and then adding the small molecule regulator until the solution turns blue; S3, placing the blue solution obtained in S2 in a hydrothermal reaction device to react, and after the reaction is completed, washing and drying the solid to obtain the tungsten oxide photocatalyst capable of selectively generating singlet oxygen.

2. The method of claim 1, wherein the method is characterized by: In S1, the volume ratio of the ethanol and water is 0.1-10:1; the total volume ratio of the mass of the small molecule regulator, ethanol and water is ≤10g:100mL, and the mass of the small molecule regulator is not 0.

3. The method of claim 1, wherein the method is characterized by: In S2, the tungsten source compound is selected from a mixture of one or more of tungsten chloride, tungstic acid, tungsten carbonyl, sodium tungstate, ammonium tungstate and tungsten ethoxide.

4. The method of claim 1, wherein the method is characterized by: In S2, the small molecule regulator is added in multiple times until the solution turns blue.

5. The method of claim 1, wherein the method is characterized by: In S2, the mass of the tungsten source compound added in 100ml of the mixed solution is ≤10g, and is not 0.

6. The method of producing a selective singlet oxygen producing tungsten oxide photocatalyst according to any one of claims 1 to 5, characterized by: In S3, the reaction temperature is 60-200℃, and the reaction time is 1-72h.

7. A tungsten oxide photocatalyst selectively producing singlet oxygen, characterized by: The tungsten oxide photocatalyst capable of selectively generating singlet oxygen is prepared by the method of any one of claims 1-6.

8. The tungsten oxide photocatalyst capable of selectively generating singlet oxygen in claim 7 is applied to photocatalytic degradation of organic pollutants.

9. Use of the selective singlet oxygen producing tungsten oxide photocatalyst according to claim 8 for the photocatalytic degradation of organic pollutants, characterized in that: The organic pollutants are chloroquine phosphate or norfloxacin or rhodamine B.

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