Preparation method of modified zinc oxide nanotube catalytic material

Abstract

The application discloses a preparation method of modified zinc oxide nanotube catalytic material and belongs to the technical field of photocatalytic materials. Deionized water, alcohol, an organic solvent, a basic solid and a zinc salt are used to prepare a one-dimensional zinc-based organic framework structure, then a colloidal solution with photocatalytic properties is mixed with the one-dimensional zinc-based organic framework structure to obtain a modified one-dimensional zinc-based organic framework structure composite material, and finally, the modified one-dimensional zinc-based organic framework structure composite material is calcined in an oxygen-inert gas mixed atmosphere to obtain a tubular catalytic material composed of modified zinc oxide nanoparticles. The one-dimensional zinc-based organic framework structure is constructed, and a calcination method is used to synthesize a tubular catalytic material composed of zinc oxide and narrow-band-gap semiconductor modified zinc oxide nanoparticles. The synthesis method is simple in operation, low in cost and small in waste generation, and can solve the problems of easy agglomeration of nanoparticle catalysts and low catalytic efficiency, so that a tubular photocatalytic material composed of ZnO nanoparticles with high photocatalytic activity is obtained.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, and in particular to a method for preparing a modified zinc oxide nanotube catalytic material. Background Technology

[0002] Zinc oxide, due to its abundant resources, low price, non-toxicity, and excellent photocatalytic properties, has become a commonly used photocatalytic material. In particular, its photocatalytic performance can be further improved through doping, semiconductor composites, modification, and carrier loading. One-dimensional zinc oxide nanostructures, with their novel photoelectric, physicochemical, and biological properties, have attracted widespread research interest from scientists, leading to their extensive applications in electronics, photocatalysis, sensing, water treatment, environmental protection, air purification, field emission, and solar cells.

[0003] Currently, most methods for preparing one-dimensional zinc oxide materials involve microemulsions, pyrolysis, hydrothermal processes, templates, solvothermal methods, microwave heating, and sol-gel methods. These methods suffer from drawbacks such as complex processes, high energy consumption, low yields, difficulty in large-scale production, and the release of toxic gases. Therefore, developing energy-saving and environmentally friendly methods for preparing one-dimensional zinc oxide nanomaterials is essential. Metal-organic frameworks (MOFs), which use metal ions as connecting points and organic ligands as supports, possess advantages such as high porosity, low density, large specific surface area, regular pores, tunable pore size, and diverse and customizable topologies. They are ideal template materials for preparing one-dimensional oxide nanomaterials, thus attracting great attention from scientists.

[0004] Using MOFs as raw materials, porous oxide nanoparticles, nanowires, nanorods, and other nanomaterials, as well as porous carbon / metal oxide composites of various shapes, have been successfully prepared. However, due to the presence of organic polymers in MOF materials, these polymers are easily decomposed during calcination, and the oxidation rate of organic matter is mismatched with the oxide formation rate, making it difficult to maintain the original morphology and thus hindering the formation of oxide nanotubes. Furthermore, while zinc oxide possesses a high band gap energy as a photocatalytic material, its low visible light utilization and high recombination rate of photogenerated electron-hole pairs result in low photocatalytic efficiency, limiting its practical application. Therefore, this invention proposes a modified preparation method for zinc oxide nanotube materials. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing modified zinc oxide nanotube catalytic materials. Using one-dimensional zinc-based MOFs as raw materials, tubular catalytic materials composed of zinc oxide nanoparticles and tubular photocatalytic materials composed of narrow-bandgap oxide in-situ modified zinc oxide nanoparticles are obtained through simple calcination treatment. This method solves the problems of easy agglomeration and low catalytic activity of nano zinc oxide particles, and improves the photocatalytic performance of zinc oxide nanotubes.

[0006] To achieve the above objectives, the present invention provides a method for preparing a modified zinc oxide nanotube catalytic material, comprising the following steps:

[0007] (1) Under continuous stirring, pure anhydrous ethanol and organic solvent were added to deionized water and ultrasonically stirred to obtain a uniformly dispersed mixed solution.

[0008] (2) Add the alkaline solid to the mixed solution obtained in step (1) and stir to obtain an alkaline organic mixed solution;

[0009] (3) Under continuous magnetic stirring, the organic ligands are added to the alkaline organic mixed solution obtained in step (2) and stirred to obtain a uniform organic ligand mixed solution.

[0010] (4) Add the solution containing zinc salt to the organic ligand mixture obtained in step (3), stir and let stand to obtain zinc-based organic framework structure precipitate solution, centrifuge, wash and dry and grind to obtain zinc-based organic framework structure powder.

[0011] (5) Add the zinc-based organic framework structure powder obtained in step (4) to the narrow band gap oxide precursor colloidal solution, stir ultrasonically, filter, dry the precipitate, grind and obtain the modified zinc-based organic framework structure powder.

[0012] (6) The modified zinc-based organic framework structure powder obtained in step (5) is calcined in a mixed atmosphere of oxygen and inert gas to obtain a tubular catalytic material composed of modified zinc oxide nanoparticles.

[0013] Preferably, in step (1), the organic solvent is any one or both of DMF and dimethyl sulfoxide;

[0014] The volume of pure anhydrous ethanol is 40–60 mL, the volume of organic solvent is 6–10 mL, and the volume of deionized water is 100–150 mL; the ultrasonic stirring time is 15–30 min.

[0015] Preferably, in step (2), the alkaline solid is any one or both of NaOH and KOH;

[0016] The amount of alkaline solid used is 2.4–4.8 g; the stirring time is 15–20 min.

[0017] Preferably, in step (3), the organic ligand is any one or more of H3BTC, EDTA, or ethylenediamine;

[0018] The amount of organic ligand used is 0.2–0.5 g; the stirring time is 15–20 min.

[0019] Preferably, in step (4), the zinc salt is any one or more of zinc nitrate, zinc acetate or zinc sulfate, the amount of zinc salt used is 0.6 to 0.8 g, and the volume of zinc salt solution is 20 to 40 mL.

[0020] Preferably, in step (4), the stirring time is 15-30 min, the standing time is 12-24 h, the drying temperature is 50-70℃, and the drying time is 5-7 h.

[0021] Preferably, in step (5), the narrow bandgap oxide precursor is any one or a mixture of tungstic acid, europium hydroxide or samarium hydroxide, and the volume of the narrow bandgap oxide precursor colloidal solution is 50 to 150 mL.

[0022] Preferably, in step (5), the ultrasonic stirring time is 15-30 min; the drying temperature is 50-70℃; and the drying time is 5-7 h.

[0023] Preferably, in step (6), the flow ratio of oxygen to inert gas is 1:100 to 1:10; the calcination temperature is 450 to 600°C; and the calcination time is 3 to 5 hours.

[0024] This invention also provides a modified zinc oxide nanotube catalytic material prepared by the above preparation method.

[0025] This invention utilizes organic ligands to generate anionic ligands under alkaline conditions, which then react with zinc ions from zinc salts to form a structurally stable one-dimensional zinc-based organic framework. By controlling the oxygen content and calcination temperature during the calcination process, the oxidation rate of the organic matter is matched with the oxide generation rate during the decomposition of the precursor organic matter, ultimately yielding a tubular structure composed of zinc oxide nanoparticles. Simultaneously, by modifying with narrow-bandgap oxide precursors, in-situ oxide-modified tubular catalytic materials composed of zinc oxide nanoparticles are synthesized, broadening the spectral response range of zinc oxide nanotubes, reducing the recombination of photogenerated electron-hole pairs, and improving the photocatalytic efficiency of zinc oxide nanotubes, resulting in a tubular catalytic material composed of zinc oxide nanoparticles with high catalytic activity and good stability.

[0026] Therefore, the method for preparing modified zinc oxide nanotube catalytic materials provided by the present invention has the following beneficial effects:

[0027] (1) The present invention prepares a stable one-dimensional zinc-based organic framework structure by co-precipitation at room temperature. Then, by controlling the oxygen content under the reaction conditions, the oxidation rate of the organic ligands in the zinc-based organic framework structure is adjusted so that the decomposition rate of the precursor organic matter and the formation rate of zinc oxide are matched, and finally a tubular catalytic material composed of zinc oxide nanoparticles is formed.

[0028] (2) Based on the synthesis of a stable one-dimensional zinc-based organic framework structure, the present invention utilizes a narrow bandgap semiconductor precursor colloidal solution to modify the structure, forming a modified one-dimensional zinc-based organic framework structure, and then synthesizes a tubular photocatalytic material composed of narrow bandgap semiconductor modified zinc oxide nanoparticles in situ by calcination.

[0029] (3) This invention constructs tubular heterostructures of zinc oxide nanoparticles in situ through modification and calcination, which broadens the spectral response range of zinc oxide, reduces the recombination of photogenerated electron-hole pairs, and improves photocatalytic efficiency, making it more widely applicable in photocatalysis, energy, wastewater treatment, environmental protection, and other fields. Furthermore, the synthesis method of this invention is simple, allows for easy control of its morphology and structure, and is easy to operate, giving it advantages for industrial application.

[0030] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0031] Figure 1 These are SEM images of the ZnO nanotube catalytic material obtained in Example 1, where (a) is a 10 μm low-magnification SEM image; and (b) is a 1 μm high-magnification SEM image.

[0032] Figure 2 The photocatalytic performance of the ZnO nanotube catalytic material and the Sm2O3 / ZnO nanotube catalytic material obtained in Example 2 under simulated sunlight;

[0033] Figure 3 These are the XRD patterns of the ZnO nanotube catalytic material and the Eu2O3 / ZnO nanotube catalytic material obtained in Example 3;

[0034] Figure 4 SEM images of the WO3 / ZnO nanotube catalytic material obtained in Example 4, wherein (a) is a 10 μm low-magnification SEM image; and (b) is a 1 μm high-magnification SEM image. Detailed Implementation

[0035] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the protection scope of the present invention.

[0036] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0037] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0038] Unless otherwise specified, the reagents, instruments, and equipment used in this invention are all commonly used by those skilled in the art.

[0039] Example 1

[0040] This embodiment provides a method for preparing zinc oxide nanotube catalytic materials, specifically including the following steps:

[0041] (1) Under continuous stirring, 40 mL of pure anhydrous ethanol and 6 mL of DMF were added to 100 mL of deionized water and ultrasonically stirred for 15 min to obtain a uniformly dispersed mixed solution.

[0042] (2) Add 2.4g of NaOH solid to the mixed solution obtained in step (1) above, stir for 15min to obtain the NaOH / DMF mixed solution;

[0043] (3) Under continuous magnetic stirring, 0.2 g of ethylenediamine was added to the NaOH / DMF mixed solution obtained in step (2), and stirred for 15 min to obtain a uniform ethylenediamine mixed solution;

[0044] (4) Add 20 mL of solution containing 0.6 g zinc sulfate to the ethylenediamine mixed solution obtained in step (3), stir for 15 min and let stand for 12 h to obtain zinc-based organic framework structure precipitate solution. After centrifugation and washing, obtain clean zinc-based organic framework structure precipitate, place the precipitate in a drying oven at 50 ℃ for 5 h, grind and obtain zinc-based organic framework structure powder.

[0045] (5) The zinc-based organic framework structure powder obtained in step (4) is calcined for 3 hours in a mixture of oxygen and inert gas (the flow ratio of oxygen and inert gas is 1:100) at a calcination temperature of 450℃, and finally zinc oxide nanotube catalytic material is obtained.

[0046] Figure 1 This is a SEM image of the ZnO nanotube catalytic material obtained in Example 1. As can be observed from the image, the obtained sample is a tubular structure composed of a large number of aggregated particles. Its surface is smooth, its structure is compact, and its cross-section shows a square opening with a side length of approximately 2 μm.

[0047] Example 2

[0048] This embodiment provides a method for preparing zinc oxide nanotube catalytic materials and Sm2O3-modified zinc oxide nanotube catalytic materials, specifically including the following steps:

[0049] (1) Under continuous stirring, 50 mL of pure anhydrous ethanol and 80 mL of DMF were added to 130 mL of deionized water and ultrasonically stirred for 20 min to obtain a uniformly dispersed mixed solution.

[0050] (2) Add 2.8g KOH to the mixed solution obtained in step (1) above, stir for 15min to obtain the KOH-DMF mixed solution;

[0051] (3) Under continuous magnetic stirring, 0.3g of EDTA was added to the KOH-DMF mixed solution obtained in step (2), and stirred for 18min to obtain a uniform EDTA mixed solution.

[0052] (4) Add 30 mL of solution containing 0.7 g zinc nitrate to the EDTA mixed solution obtained in step (3), stir for 20 min and let stand for 20 h to obtain zinc-based organic framework structure precipitate solution. After centrifugation and washing, obtain clean zinc-based organic framework structure precipitate, place the precipitate in a drying oven at 60 ℃ for 6 h, grind and obtain zinc-based organic framework structure powder.

[0053] (5) Add the zinc-based organic framework structure powder obtained in step (4) to 50 mL of samarium hydroxide colloidal solution, stir ultrasonically for 30 min, filter the precipitate solution, and place the precipitate in a drying oven at 70 °C for 5 h to dry. After grinding, the modified zinc-based organic framework structure powder is obtained.

[0054] (6) The zinc-based organic framework structure powders obtained in steps (4) and (5) were calcined for 5 hours in a mixture of oxygen and inert gas (the flow ratio of oxygen and inert gas was 1:50) at a calcination temperature of 550℃, and finally zinc oxide nanotubes and Sm2O3 modified zinc oxide nanotube catalytic materials were obtained respectively.

[0055] Figure 2 The photocatalytic performance of the ZnO nanotube catalytic materials and the Sm2O3 / ZnO nanotube catalytic materials obtained in Example 2 under simulated sunlight is shown. C0 is the initial concentration of organic pollutants in the solution, Ct This represents the concentration of organic pollutants in the solution at time t. From... Figure 2 As can be seen, within 120 minutes, the degradation rate of pure zinc oxide was approximately 46%, while with the modification of Sm2O3, the degradation rate of the obtained sample increased by approximately 28% compared to the ZnO sample. This indicates that the modification of ZnO with Sm2O3 can improve the photocatalytic performance of the ZnO sample.

[0056] Example 3

[0057] This embodiment provides a method for preparing a zinc oxide nanotube catalytic material and an Eu2O3-modified zinc oxide nanotube catalytic material, specifically including the following steps:

[0058] (1) Under continuous stirring, 60 mL of pure anhydrous ethanol and 10 mL of dimethyl sulfoxide were added to 150 mL of deionized water and ultrasonically stirred for 30 min to obtain a uniformly dispersed mixed solution.

[0059] (2) Add 2.4g NaOH and 2.4g KOH solid to the mixed solution obtained in step (1) above, stir for 20min to obtain a NaOH-KOH / dimethyl sulfoxide mixed solution;

[0060] (3) Under continuous magnetic stirring, 0.5 g of H3BTC and EDTA mixture was added to the NaOH-KOH / dimethyl sulfoxide mixed solution obtained in step (2), and stirred for 20 min to obtain a uniform dimethyl sulfoxide mixed solution;

[0061] (4) Add 40 mL of solution containing 0.8 g zinc sulfate to the dimethyl sulfoxide mixed solution obtained in step (3), stir for 30 min and let stand for 24 h to obtain zinc-based organic framework structure precipitate solution, centrifuge and wash to obtain clean zinc-based organic framework structure precipitate, place the precipitate in a drying oven at 70 ℃ for 7 h, grind to obtain zinc-based organic framework structure powder.

[0062] (5) Add the zinc-based organic framework structure powder obtained in step (4) to 150 mL europium hydroxide colloidal solution, stir ultrasonically for 30 min, filter the precipitate solution, and place the precipitate in a drying oven at 70 °C for 7 h to dry. After grinding, the modified zinc-based organic framework structure powder is obtained.

[0063] (6) The zinc-based organic framework structure powders obtained in steps (4) and (5) were calcined for 5 hours in a mixture of oxygen and inert gas (the flow rate ratio of oxygen and inert gas was 1:10) at a calcination temperature of 600℃, and finally zinc oxide nanotubes and Eu2O3 modified zinc oxide nanotube catalytic materials were obtained respectively.

[0064] Figure 3The images show the XRD patterns of the ZnO nanotube catalytic material and the Eu2O3 / ZnO nanotube catalytic material obtained in Example 3. Figure 3 It can be seen that both ZnO and Eu2O3 / ZnO samples exhibit obvious diffraction peaks at 2θ = 31.7°, 34.4°, 36.2°, 47.6°, 56.6°, 62.9°, and 67.9°, which correspond to the (100), (002), (101), (102), (110), (103), and (112) crystal plane diffraction peaks of ZnO, respectively. However, in the Eu2O3 / ZnO sample, in addition to the characteristic peaks of ZnO, Eu2O3 (211), (222), and (400) crystal plane diffraction peaks also appear at 2θ = 19.9°, 28.4°, and 32.9°, respectively, indicating that the obtained sample is an Eu2O3 / ZnO composite material.

[0065] Example 4

[0066] This embodiment provides a method for preparing a zinc oxide nanotube catalytic material and a WO3-modified zinc oxide nanotube catalytic material, specifically including the following steps:

[0067] (1) Under continuous stirring, 45 mL of pure anhydrous ethanol and 8 mL of DMF were added to 120 mL of deionized water and ultrasonically stirred for 30 min to obtain a uniformly dispersed mixed solution.

[0068] (2) Add 3.6g NaOH to the mixed solution obtained in step (1) above, stir for 15min to obtain the NaOH / DMF mixed solution;

[0069] (3) Under continuous magnetic stirring, 0.4 g of H3BTC was added to the alkaline organic mixed solution obtained in step (2), and after stirring for 15 min, a uniform H3BTC mixed solution was obtained.

[0070] (4) Add 40 mL of solution containing 0.6 g of zinc acetate to the H3BTC mixed solution obtained in step (3), stir for 30 min and let stand for 18 h to obtain zinc-based organic framework structure precipitate solution. After centrifugation and washing, a clean zinc-based organic framework structure precipitate is obtained. The precipitate is placed in a drying oven at 60 °C and dried for 6 h. After grinding, zinc-based organic framework structure powder is obtained.

[0071] (5) Add the zinc-based organic framework structure powder obtained in step (4) to 100 mL of tungstic acid colloidal solution, stir ultrasonically for 20 min, filter the precipitate solution, and place the precipitate in a drying oven at 60 °C for 5 h to dry. After grinding, the modified zinc-based organic framework structure powder is obtained.

[0072] (6) The zinc-based organic framework structure powders obtained in steps (4) and (5) were calcined for 3 hours in a mixture of oxygen and inert gas (the flow rate ratio of oxygen and inert gas was 1:20) at a calcination temperature of 500℃, and finally zinc oxide nanotubes and WO3-modified zinc oxide nanotube catalytic materials were obtained respectively.

[0073] Figure 4 SEM images of the ZnO nanotube catalytic material and the WO3 / ZnO nanotube catalytic material obtained in Example 4. From... Figure 4 As can be seen, WO3 modification did not change the tubular structure of the sample, and its size did not change significantly. However, the sample surface became rougher, with a large number of particles accumulating on the surface. This result indicates that WO3 modification did not change the shape of the ZnO nanotubes.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a modified zinc oxide nanotube catalytic material, characterized in that, Includes the following steps: (1) Under continuous stirring, pure anhydrous ethanol and organic solvent were added to deionized water and ultrasonically stirred to obtain a uniformly dispersed mixed solution; (2) Add the alkaline solid to the mixed solution obtained in step (1) and stir to obtain an alkaline organic mixed solution; (3) Under continuous magnetic stirring, the organic ligands are added to the alkaline organic mixed solution obtained in step (2) and stirred to obtain a uniform organic ligand mixed solution; (4) Add the solution containing zinc salt to the organic ligand mixture obtained in step (3), stir and let stand to obtain zinc-based organic framework structure precipitate solution, centrifuge, wash and dry and grind to obtain zinc-based organic framework structure powder. (5) Add the zinc-based organic framework structure powder obtained in step (4) to the narrow band gap oxide precursor colloidal solution, stir ultrasonically, filter, dry the precipitate, grind and obtain the modified zinc-based organic framework structure powder. (6) The modified zinc-based organic framework structure powder obtained in step (5) is calcined in a mixed atmosphere of oxygen and inert gas to obtain a tubular catalytic material composed of modified zinc oxide nanoparticles; In step (6), the flow ratio of oxygen to inert gas is 1:100 to 1:10; the calcination temperature is 450 to 600℃; and the calcination time is 3 to 5 hours.

2. The method for preparing a modified zinc oxide nanotube catalytic material according to claim 1, characterized in that: In step (1), the organic solvent is any one or both of DMF and dimethyl sulfoxide; The volume of pure anhydrous ethanol is 40-60 mL, the volume of organic solvent is 6-10 mL, and the volume of deionized water is 100-150 mL; the ultrasonic stirring time is 15-30 min.

3. The method for preparing a modified zinc oxide nanotube catalytic material according to claim 1, characterized in that: In step (2), the alkaline solid is any one or both of NaOH and KOH; The amount of alkaline solid used is 2.4~4.8g; the stirring time is 15~20min.

4. The method for preparing a modified zinc oxide nanotube catalytic material according to claim 1, characterized in that: In step (3), the organic ligand is any one or more of H3BTC, EDTA, or ethylenediamine; The amount of organic ligand used is 0.2~0.5g; the stirring time is 15~20 min.

5. The method for preparing a modified zinc oxide nanotube catalytic material according to claim 1, characterized in that: In step (4), the zinc salt is any one or more of zinc nitrate, zinc acetate or zinc sulfate, the amount of zinc salt used is 0.6~0.8g, and the volume of zinc salt solution is 20~40 mL.

6. The method for preparing a modified zinc oxide nanotube catalytic material according to claim 1, characterized in that: In step (4), the stirring time is 15~30 min, the standing time is 12~24 h, the drying temperature is 50~70 ℃, and the drying time is 5~7 h.

7. The method for preparing a modified zinc oxide nanotube catalytic material according to claim 1, characterized in that: In step (5), the narrow bandgap oxide precursor is any one or a mixture of tungstic acid, europium hydroxide or samarium hydroxide, and the volume of the narrow bandgap oxide precursor colloidal solution is 50~150mL.

8. The method for preparing a modified zinc oxide nanotube catalytic material according to claim 1, characterized in that: In step (5), the ultrasonic stirring time is 15~30 min; the drying temperature is 50~70℃ and the drying time is 5~7 h.

9. A modified zinc oxide nanotube catalytic material, characterized in that: The modified zinc oxide nanotube catalytic material is prepared by the preparation method described in any one of claims 1-8.

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