Preparation method and application of zirconium-based metal organic framework UiO-66 bismuth tungstate-loaded photocatalyst
阅读说明：本技术 锆基金属有机框架UiO-66负载钨酸铋的光催化剂的制备方法及应用 (Preparation method and application of zirconium-based metal organic framework UiO-66 bismuth tungstate-loaded photocatalyst ) 是由 刘德钊 何宇轩 代小蓉 满尊 颜诚 于 2021-06-25 设计创作，主要内容包括：本发明公开了一种锆基金属有机框架UiO-66负载Bi-(2)WO-(6)的光催化剂的制备方法及应用,该方法包括：将氯化锆和1,4-苯二甲酸溶于DMF中,再加入CH-(3)COOH溶液进行反应,反应后制得UiO-66；将Bi(NO-(3))-(3)·5H-(2)O溶解在N,N-二甲基甲酰胺(DMF)中,得到溶液A。通过搅拌将Na-(2)WO-(6)·2H-(2)O溶解在去离子水中待完全溶解后,将UiO-66加入混合均匀,得到溶液B。将溶液A倒至溶液B得到溶液C,进行反应,将所得固体产物经后处理得到光催化剂。本发明通过将窄带隙的Bi-(2)WO-(6)作为活性组分负载在UiO-66载体上,提高可见光吸收性能及催化效率。(The invention discloses a zirconium-based metal organic framework UiO-66 loaded Bi 2 WO 6 The preparation method and the application of the photocatalyst comprise the following steps: dissolving zirconium chloride and 1, 4-phthalic acid in DMF, and adding CH 3 Reacting the COOH solution to obtain UiO-66; adding Bi (NO) 3 ) 3 ·5H 2 O was dissolved in N, N-Dimethylformamide (DMF) to give solution a. Mixing Na 2 WO 6 ·2H 2 And dissolving O in deionized water, adding the UiO-66, and uniformly mixing to obtain a solution B. Pouring the solution A into the solution B to obtain a solution C, reacting, and treating the obtained solid productAnd (4) processing to obtain the photocatalyst. The invention is to use Bi with narrow band gap 2 WO 6 The active component is loaded on the UiO-66 carrier, so that the visible light absorption performance and the catalytic efficiency are improved.)
1. Zirconium-based metal organic framework UiO-66 loaded Bi2WO6The method for preparing the photocatalyst is characterized by comprising the following steps:
(1) dissolving zirconium chloride and 1, 4-phthalic acid in N, N-dimethylformamide, and adding CH3Reacting the COOH solution, and performing post-treatment on the solution after the reaction to obtain a white solid, namely UiO-66;
(2) adding Bi (NO)3)3·5H2Dissolving O in N, N-dimethylformamide to obtain a solution A;
(3) mixing Na2WO6·2H2Dissolving O in deionized water, and adding and uniformly mixing the UiO-66 obtained in the step (1) after the O is completely dissolved to obtain a solution B;
(4) pouring the obtained solution A into the solution B to obtain a solution C, reacting the solution C, cooling the reaction, and carrying out post-treatment on the obtained solid product to obtain the zirconium-based metal organic framework UiO-66 loaded Bi2WO6The photocatalyst of (1).
2. The method according to claim 1, wherein in the step (1), the reaction is: then adding CH3And magnetically stirring the mixed solution with the COOH solution for 10-60 minutes, ultrasonically shaking for 10-60 minutes, transferring to a reaction kettle, and placing in a vacuum drying oven at 100-140 ℃ for 12-36 hours.
3. The method according to claim 1, wherein in the step (1), the molar ratio of the zirconium chloride to the 1, 4-phthalic acid is 0.5 to 2: 1.
4. the method according to claim 1, wherein in the step (1), the post-treatment comprises: cooling, centrifuging, washing, drying and grinding.
5. The method according to claim 4, wherein in the step (1), the solid obtained by centrifugation is washed 2 to 4 times with N, N-dimethylformamide and ethanol;
the drying conditions are as follows: drying for 4-12 h by a vacuum drying oven at 70-90 ℃.
6. The method according to claim 1, wherein in the step (4), Bi (NO) in the solution A3)3·5H2O and Na in the solution B2WO6·2H2The molar ratio of O is 1-3: 1.
7. the method according to claim 1, wherein in the step (4), the reacting of the solution C specifically comprises:
stirring the solution C for 10-60 minutes, transferring the solution C into a reaction kettle, and then placing the reaction kettle into a vacuum drying oven at 100-140 ℃ for 6-18 hours.
8. The preparation method according to claim 1, wherein in the step (4), the post-treatment specifically comprises: washing with N, N-dimethylformamide and deionized water for several times, and drying in a vacuum drying oven at 70-90 ℃ for 4-10 hours.
9. The zirconium-based metal organic framework UiO-66 prepared by the preparation method of any one of claims 1 to 8 loaded with Bi2WO6The use of the photocatalyst of (a) in the catalytic removal of cresol.
Technical Field
The invention relates to the technical field of photocatalysts and preparation thereof, in particular to a zirconium-based metal organic framework UiO-66 loaded Bi2WO6The preparation method and application of the photocatalyst.
Background
The problem of increasingly serious environmental pollution is a worldwide problem, and the survival and sustainable development of human beings are increasingly influenced. In recent years, various technologies for treating environmental pollution have been studied, and among them, a technology for removing pollutants using a photocatalytic material has received much attention. The traditional photocatalytic material is generally metal oxide with wider band gap, and has a plurality of defects in practical application: (1) the photoresponse range is narrow, such as the traditional photocatalytic material TiO2The forbidden band width of the photocatalyst is 3.2eV, and the photocatalyst only has a good photocatalytic effect in an ultraviolet region; (2) the quantity of photo-generated electrons and holes is small, and recombination is easy to occur.
The bismuth-based oxide is widely applied to visible light catalysis for removing environmental pollutants due to the unique layered structure, controllable micro-morphology and good visible light response characteristic. Bi2WO6Because of stable chemical structure, the material is superior to the traditional photocatalytic material TiO2Has been widely studied for obtaining visible light capturing ability, but Bi alone2WO6The electrons and holes are easy to recombine after being excited by light, and the activity of the electrons and holes is limited, so that the current Bi needs to be treated2WO6Further research and improvement are carried out to obtain the photocatalytic material with stable structure and high efficiency.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a zirconium-based metal organic framework UiO-66 loaded Bi2WO6The preparation method and the application of the photocatalyst are realized by mixing Bi with narrow band gap2WO6The active component is loaded on the UiO-66 carrier, so that the visible light absorption performance and the catalytic efficiency are improved.
The carrier adopted by the invention is UiO-66 which is a zirconium-based Metal Organic Framework (MOFs), and the unique carrier isThe octahedral structure is Bi2WO6The loading of the composite material provides sites, and the large specific surface area can also enhance the adsorption and ion exchange performance of pollutants and accelerate the degradation of the pollutants.
The invention provides the zirconium-based metal organic framework UiO-66 loaded Bi2WO6The preparation method of the photocatalyst comprises the following steps:
(1) zirconium chloride ZrCl4And 1, 4-phthalic acid in N, N-Dimethylformamide (DMF), and adding CH3Reacting the COOH solution, and performing post-treatment on the solution after the reaction to obtain a white solid, namely UiO-66;
(2) adding Bi (NO)3)3·5H2O was dissolved in N, N-Dimethylformamide (DMF) to give solution a.
(3) Mixing Na2WO6·2H2And (3) dissolving O in deionized water until the O is completely dissolved, adding the UiO-66 obtained in the step (1) and uniformly mixing to obtain a solution B.
(4) Pouring the obtained solution A into the solution B to obtain a solution C, reacting the solution C, cooling the reaction, and carrying out post-treatment on the obtained solid product to obtain the zirconium-based metal organic framework UiO-66 loaded Bi2WO6The photocatalyst of (1).
In the step (1), the reaction is as follows: then adding CH3And magnetically stirring the mixed solution with the COOH solution for 10-60 minutes, ultrasonically shaking for 10-60 minutes, transferring to a reaction kettle, and placing in a vacuum drying oven at 100-140 ℃ for 12-36 hours. Further preferably, the reaction is: then adding CH3And magnetically stirring the mixed solution with the COOH solution for 20-40 minutes, ultrasonically shaking for 20-40 minutes, transferring into a reaction kettle, and placing in a vacuum drying oven at 110-130 ℃ for 18-30 hours.
The zirconium chloride ZrCl4The molar ratio of the 1, 4-phthalic acid to the 1, 4-phthalic acid is 0.5-2: 1, more preferably 0.8 to 1.5: 1, most preferably 1: 1.
the post-treatment comprises the following steps: cooling, centrifuging, washing, drying and grinding.
The washing is that the solid obtained by centrifugation is washed 2-4 times by using N, N-Dimethylformamide (DMF) and ethanol respectively.
The drying conditions are as follows: drying for 4-12 h by a vacuum drying oven at 70-90 ℃.
In the step (4), Bi (NO) in the solution A3)3·5H2O and Na in the solution B2WO6·2H2The molar ratio of O is 1-3: 1, most preferably 2: 1.
in the step (4), the reaction of the solution C specifically comprises the following steps:
stirring the solution C for 10-60 minutes, transferring the solution C into a reaction kettle, and then placing the reaction kettle into a vacuum drying oven at 100-140 ℃ for 6-18 hours;
further preferably, the reaction of the solution C specifically comprises:
stirring the solution C for 20-40 minutes, transferring the solution C into a reaction kettle, and then placing the reaction kettle into a vacuum drying oven at the temperature of 110-130 ℃ for 10-14 hours;
in the step (4), the post-treatment specifically comprises: washing with N, N-Dimethylformamide (DMF) and deionized water for several times, and drying in a vacuum drying oven at 70-90 deg.C for 4-10 hr.
Most preferably, the invention provides the zirconium-based metal organic framework UiO-66 loaded with Bi2WO6The preparation method of the photocatalyst comprises the following steps:
(1) zirconium chloride ZrCl4And 1, 4-phthalic acid in N, N-Dimethylformamide (DMF), and adding CH3And magnetically stirring the mixed solution with the COOH solution for 30 minutes, ultrasonically shaking for 30 minutes, transferring the mixed solution into a 150mL stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, keeping the reaction kettle in a vacuum drying oven at 120 ℃ for 24 hours, after the solution is cooled to room temperature after the reaction, respectively washing the obtained solid by centrifugation with DMF (dimethyl formamide) and ethanol for 3 times, drying the solid overnight in the vacuum drying oven at 80 ℃ and grinding the solid to obtain a white solid, namely UiO-66.
(2) Adding Bi (NO)3)3·5H2O was dissolved in DMF and stirring was continued for 30min to give solution a.
(3) By vigorous stirringMixing with Na2WO6·2H2Slowly dissolving O in deionized water until the O is completely dissolved, and adding Bi: zr 1: 0.5-2 of UiO-66 is added into the solution and stirred for 30 minutes to obtain a solution B.
(4) The resulting solution A was slowly poured into solution B to give solution C, which was stirred for 30 minutes and then transferred to a stainless steel Teflon lined autoclave, which was then placed in a 120 ℃ vacuum drying oven for 12 hours.
(5) And (3) after the reaction kettle is cooled to room temperature, washing the obtained solid product for several times by using DMF (dimethyl formamide) and deionized water, and drying in a vacuum drying oven at the temperature of 80 ℃ for 6-8 hours.
In the above-mentioned production method, preferably, ZrCl is used in the step (1)4:1, 4-benzenedicarboxylic acid ═ 1: 1.
in the above production method, it is preferable that Bi (NO) is used in the step (2)3)3·5H2O and Na in the step (3)2WO6·2H2The molar ratio of O is 2: 1.
The zirconium-based metal organic framework UiO-66 prepared by the preparation method is loaded with Bi2WO6The use of the photocatalyst of (a) in the catalytic removal of cresol.
Compared with the prior art, the invention has the following advantages:
bi prepared by the method of the invention2WO6the/UiO-66 composite photocatalyst has higher photocatalytic activity, and 0.1g of Bi is irradiated by a xenon lamp simulating sunlight2WO6The degradation rate of the/UiO-66 composite photocatalyst in paracresol gas with the flow rate of 100mL/min and the initial concentration of 390ppb can reach 95 percent and be maintained for more than 5 hours, which is much higher than that of single Bi2WO6。
Drawings
FIG. 1 shows Bi2WO6A graph of the p-cresol removal effect of UiO-66;
FIG. 2 is a monomer and composite XRD pattern;
FIG. 3 is SEM image of composite material of different proportions, (a) Bi2WO6，(b)UiO-66，(c)BZ 0.5，(d)BZ 1，(e)BZ 2；
In fig. 4, the left side is a nitrogen adsorption and desorption isotherm, and the right side is desorption pore size distribution;
in FIG. 5, the left side shows the UV-visible diffuse reflectance spectrum, and the right side shows (ahv)2A plot of photon energy (hv);
FIG. 6 is a Mott-Schottky graph of a monomer and a composite;
FIG. 7 is a schematic illustration of the catalytic mechanism.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following further illustrates the present invention with reference to the accompanying drawings and specific examples, but the present invention is not limited to the following examples
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and the terms used in the specification of the present invention are for the purpose of describing particular embodiments only and are not intended to limit the present invention.
Example 1
Zirconium-based metal organic framework UiO-66 loaded Bi2WO6The preparation method of the photocatalyst comprises the following specific steps:
(1) zirconium chloride ZrCl4(0.233g, 1mmol), 1, 4-phthalic acid (0.166g, 1mmol) was dissolved in 60mL of N, N-Dimethylformamide (DMF), and 12g of CH was added3And magnetically stirring the mixed solution with a COOH solution (99.5 percent and 0.2mol) for 30min, ultrasonically oscillating for 30min, transferring to a 150mL stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, placing the reaction kettle in a vacuum drying box at 120 ℃ for 24h, after the reaction, cooling the solution to room temperature of 25 ℃, centrifuging the solution at the speed of 5000r/min for 3min, alternately washing the obtained solid with DMF and ethanol for 3 times, drying the solid in the vacuum drying box at the temperature of 80 ℃ for 8h, and grinding the solid to obtain pure white solid powder UiO-66.
(2) By vigorous stirring 0.099g (3mmol) Na2WO6·2H2O was slowly dissolved in 30mL of deionized water, 0.083g (0.5mmol) of UiO-66 was added thereto after complete dissolution, and the resulting mixture solution was kept stirring for 1 h. 2.910g (6mmol) of Bi (NO)3)3·5H2O was dissolved in 30mL of DMF, and the Bi (NO) was added3)3The DMF solution is added to the mixed solution prepared as described in the above step to form a reaction precursor. The reaction precursor was stirred for an additional 30min and transferred to a 150mL stainless steel Teflon lined autoclave which was then placed in a 120 ℃ vacuum oven for 12 h. Finally, washing the solid product with DMF and ultrapure water for several times, drying in a vacuum drying oven at 80 ℃ for 7h, and grinding to obtain Bi with corresponding proportion2WO6the/UiO-66 composite is denoted as BZ 1.
Example 2
Zirconium-based metal organic framework UiO-66 loaded Bi2WO6The preparation method of the photocatalyst comprises the following specific steps:
(1) zirconium chloride ZrCl4(0.233g, 1mmol), 1, 4-phthalic acid (0.166g, 1mmol) was dissolved in 60mL of N, N-Dimethylformamide (DMF), and 12g of CH was added3And magnetically stirring the mixed solution with a COOH solution (99.5 percent and 0.2mol) for 30min, ultrasonically oscillating for 30min, transferring to a 150mL stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, placing the reaction kettle in a vacuum drying box at 120 ℃ for 24h, after the reaction, cooling the solution to room temperature of 25 ℃, centrifuging the solution at the speed of 5000r/min for 3min, alternately washing the obtained solid with DMF and ethanol for 3 times, drying the solid in the vacuum drying box at the temperature of 80 ℃ for 8h, and grinding the solid to obtain pure white solid powder UiO-66.
(2) By vigorous stirring 0.099g (3mmol) Na2WO6·2H2O was slowly dissolved in 30mL of deionized water, 0.166g (1mmol) of UiO-66 was added thereto after complete dissolution, and the resulting mixture solution was kept stirring for 1 h. 2.910g (6mmol) of Bi (NO)3)3·5H2O was dissolved in 30mL of DMF, and the Bi (NO) was added3)3The DMF solution is added to the mixed solution prepared as described in the above step to form a reaction precursor. The reaction precursor was stirred for an additional 30min and transferred to a 150mL stainless steel Teflon lined autoclave which was then placed in a 120 ℃ vacuum oven for 12 h. Finally, the solid product was washed several times with DMF and ultrapure water and placed under vacuum at 80 ℃Drying in an air drying oven for 7h, and grinding to obtain Bi with corresponding ratio2WO6the/UiO-66 composite is noted as BZ 0.5.
Example 3
Zirconium-based metal organic framework UiO-66 loaded Bi2WO6The preparation method of the photocatalyst comprises the following specific steps:
(1) zirconium chloride ZrCl4(0.233g, 1mmol), 1, 4-phthalic acid (0.166g, 1mmol) was dissolved in 60mL of N, N-Dimethylformamide (DMF), and 12g of CH was added3And magnetically stirring the mixed solution with a COOH solution (99.5 percent and 0.2mol) for 30min, ultrasonically oscillating for 30min, transferring to a 150mL stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, placing the reaction kettle in a vacuum drying box at 120 ℃ for 24h, after the reaction, cooling the solution to room temperature of 25 ℃, centrifuging the solution at the speed of 5000r/min for 3min, alternately washing the obtained solid with DMF and ethanol for 3 times, drying the solid in the vacuum drying box at the temperature of 80 ℃ for 8h, and grinding the solid to obtain pure white solid powder UiO-66.
(2) By vigorous stirring 0.099g (3mmol) Na2WO6·2H2O was slowly dissolved in 30mL of deionized water, 0.0415g (0.25mmol) of UiO-66 was added thereto after complete dissolution, and the resulting mixture solution was kept stirring for 1 h. 2.910g (6mmol) of Bi (NO)3)3·5H2O was dissolved in 30mL of DMF, and the Bi (NO) was added3)3The DMF solution is added to the mixed solution prepared as described in the above step to form a reaction precursor. The reaction precursor was stirred for an additional 30min and transferred to a 150mL stainless steel Teflon lined autoclave which was then placed in a 120 ℃ vacuum oven for 12 h. Finally, washing the solid product with DMF and ultrapure water for several times, drying in a vacuum drying oven at 80 ℃ for 7h, and grinding to obtain Bi with corresponding proportion2WO6the/UiO-66 composite is denoted as BZ 2.
It should be noted that. For comparison of Bi prepared in the examples of the invention2WO6UiO-66 with the catalytic effect of the monomer Bi2WO6And monomer UiO-66 and Bi obtained in example2WO6Irradiation of visible light by UiO-66The degradation experiment was carried out using p-cresol as the process gas.
Firstly, a xenon lamp is used as a light source to carry out a photocatalytic degradation experiment, and the temperature of the xenon lamp is controlled by a cold trap to ensure that the external temperature condition is unchanged. Other experimental conditions were: the concentration of p-cresol gas was 390ppb, the gas flow rate was 150mL/min, and the amount of material used was 0.1 g. In order to ensure that the catalysis of the material is dominant, dark reaction adsorption is carried out after ventilation, and a xenon lamp is started after the concentration of the discharged gas is stable.
FIG. 1 shows a monomer Bi2WO6And monomer UiO-66 and Bi obtained in example2WO6The photocatalytic degradation effect of/UiO-66 on p-cresol is shown, and the result shows that Bi2WO6UiO-66 ratio of monomer Bi2WO6Has better treatment effect and service life.
FIG. 2 shows a monomer Bi2WO6And monomer UiO-66 and Bi obtained in example2WO6XRD characterization of/UiO-66, from which Bi is seen2WO6The UiO-66 has the monomer Bi at the same time2WO6And diffraction peaks of monomer UiO-66, indicating Bi2WO6Successfully compounded with UiO-66, and Bi2WO6The introduction of (A) did not affect the crystal structure of UiO-66.
FIG. 3 shows a monomer Bi2WO6And monomer UiO-66 and Bi obtained in example2WO6SEM picture of/UiO-66, from which the flaky Bi is seen2WO6Form a ball flower structure on the surface of the octahedron UiO-66 and along with Bi2WO6The increase of the proportion increases the amount of the ball flowers correspondingly.
FIG. 4 shows a monomer Bi2WO6And monomer UiO-66 and Bi obtained in example2WO6Nitrogen adsorption and desorption isotherms and desorption pore size distribution diagrams of/UiO-66. As can be seen from the figure, with Bi2WO6The specific surface area of the composite is gradually reduced when the proportion of the composite is increased.
FIG. 5 shows Bi2WO6And monomer UiO-66 and Bi obtained in example2WO6UV-visible diffuse reflectance of/UiO-66Spectra. Pure UiO-66 and Bi2WO6Forbidden band width E ofg4.08eV and 3.32eV respectively, and the forbidden bandwidth E of the composite material BZ 2g3.35eV, indicating UiO-66 and Bi2WO6Compared with the UiO-66 monomer material, the composite material has better visible light absorption capacity and more excellent catalytic performance.
FIG. 6 shows Bi2WO6And monomer UiO-66 and Bi obtained in example2WO6Mott-Schottky plot of/UiO-66. Bi2WO6And UiO-66 and the band gap width E of the composite material thereofgIt has been calculated by uv-vis diffuse reflectance characterization results, while the flat band potential is usually analytically calculated by Mott-Schottky curves. Bi can be obtained by calculation2WO6Valence band sites E of UiO-66 and BZ 2VB2.51eV, 3.43eV and 2.04eV, respectively.
FIG. 7 shows Bi obtained in example2WO6Reaction mechanism diagram of/UiO-66. According to formula Eg＝EVB+ECBCan calculate the valence band point position EVB. Calculated to obtain Bi2WO6Valence band sites EVB for UiO-66 and BZ 2 are 2.51eV, 3.43eV and 2.04eV, respectively. According to the above results, Bi is proposed2WO6The possible photocatalytic mechanism of UiO-66. Bi2WO6The photocatalytic effect of the/UiO-66 composite material is improved by the Bi2WO6And ulio-66 appropriate valence band matching and heterojunction formation. Under the action of a visible light source, Bi2WO6And electrons in the valence band of the UiO-66 material are transferred to the conduction band, the valence band generates corresponding holes, and Bi is generated due to the existence of heterojunction2WO6And UiO-66 will produce a contact interface, Bi2WO6Has a conduction band lower than UiO-66, e-Can be prepared from Bi2WO6The conduction band is transferred to the UiO-66 conduction band. Bi2WO6And the conduction band of UiO-66 are both below the potential ratioE on the conduction band-Can reduce oxygen adsorbed by the composite material into O2 -And as active species to catalyze the degradation of VOCs. And the hole generated after the electron transfer on the valence band can also oxidize and degrade the pollutants. In addition, since Bi2WO6Is more negative than the valence band position of UiO-66, at e-From Bi2WO6H while the conduction band is transferred to the UiO-66 conduction band+Also transferred from the UiO-66 valence band to Bi2WO6The valence band. The transfer directions of the photo-generated electrons and the holes are opposite, so that the recombination of the photo-generated electrons and the holes is inhibited, and the generation of active species and the degradation efficiency of VOCs are promoted.
Table 1 shows the monomers Bi2WO6And monomer UiO-66 and Bi obtained in example2WO6The structural parameters of/UiO-66, Bi can be seen from the table2WO6The total pore volume and the specific surface area of the composite material are both smaller than those of the monomer UiO-66, and the pore diameter is slightly increased.
TABLE 1 Bi2WO6UiO-66 and composite material texture parameters
The above-mentioned embodiments of the present invention are only examples used in the experiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
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