CN101311119B - Reticular nanoporous zinc oxide micron hollow sphere and preparation method thereof - Google Patents

Abstract

The invention discloses a mesh nanoporous zinc oxide micron hollow sphere and a preparation method thereof. The material is a zinc oxide micron hollow sphere whose surface is a network nanopore, wherein the diameter of the hollow sphere is 1 to 10 μm, and the diameter of the nanopore is 50 to 100 nm; the method includes a liquid phase chemical method, especially (a) according to the zinc Salt: chelating agent: sodium citrate: water = 1: 0.5-1.5: 0.05-0.15: 50-150 molar ratio, after weighing, put it in a container and stir to dissolve, keep it in a sealed state at 70-100°C for 3 The product is obtained in ~10 hours; (b) the product is first filtered, and washed with water for more than one time, and then heated at 300-500 ° C for 1-3 hours to obtain a mesh nanoporous zinc oxide micron hollow sphere, the The zinc salt is zinc nitrate or zinc acetate or zinc chloride or zinc sulfate, and the chelating agent is urea or ammonia or hexamethylenetetramine or ammonium hydroxide. Hollow spheres can be widely used in drug delivery, chemical reaction carriers, cosmetics, coatings, catalytic and photocatalytic materials and other fields.

Description

Reticular nanoporous zinc oxide micron hollow sphere and preparation method thereof

Technical Field The present invention relates to a zinc oxide hollow sphere and its preparation method, in particular to a net-shaped nanoporous zinc oxide micron hollow sphere and its preparation method.

Background Art With the rapid development of modern industry, while enjoying the benefits brought by modern technology, people have also tasted the evil result of industrialization—environmental pollution. Since the discovery that semiconductor materials can catalyze the degradation of organic pollutants after exposure to light, the search for efficient and non-toxic catalysts has been the goal of people's efforts, and very fruitful research and application results have been achieved. Semiconductor materials, especially wide-bandgap semiconductors, such as titanium dioxide and zinc oxide, have shown broad application prospects in wastewater treatment, air purification, and photochemical cells. An important condition for improving the efficiency of photocatalytic reactions is that the catalytic material has a relatively high specific surface area, and nanomaterials just meet this requirement. However, when the material is reduced to a certain scale, especially nanoparticles, the agglomeration phenomenon due to the electrostatic interaction on the surface has always been a problem that hinders the application of nanopowder materials. Nanomaterials with a hollow sphere structure have the characteristics of light specific gravity, large specific surface area, and strong permeability. They have important application prospects in drug delivery carriers, chemical reaction carriers, cosmetics, coatings, catalytic and photocatalytic materials, etc., especially in catalytic field, the problem of nanoparticle agglomeration can be further overcome. At present, people have made some attempts and efforts in order to obtain nano-powder materials with hollow sphere structures, such as a kind of "oxidation with zinc powder as raw material" disclosed in the Chinese invention patent specification CN 1305803C announced on March 21, 2007. Preparation method of zinc hollow spheres". It adopts wet chemical method, that is, zinc powder is used as raw material, the surface of excess zinc powder is treated with acid, ammonia water is used as precipitant, and Zn core/Zn(OH) ₂ shell composite particle precipitate is first formed in the liquid phase, and precipitated After separation, washing and drying, the Zn(OH) ₂ shell is decomposed into ZnO, and the zinc core is volatilized or oxidized to form a zinc oxide hollow sphere structure by calcining at 600-950 °C. However, there are deficiencies in this preparation method. First of all, it cannot produce zinc oxide micron hollow spheres whose surface is a network-like nanometer-sized porous structure; secondly, it uses zinc powder as a starting material, so the prepared oxide The shape and quality of the zinc hollow spheres depend entirely on the shape and quality of the raw zinc powder. The diameter of the final zinc oxide hollow spheres is equivalent to the size of the initial zinc powder. To obtain uniform zinc oxide hollow spheres, it is necessary to Zinc powder must be screened, which will increase the cost of production; again, the precursor product obtained in the preparation is a core/shell structure of Zn/Zn(OH) ₂ , which needs to be calcined at a relatively high temperature of 600-900 °C , so that the surface Zn(OH) ₂ is converted into zinc oxide, and the zinc inside is evaporated and oxidized at the same time, so the shape and size of the hollow part in the ball are difficult to control; finally, the organic solvent ethanol is used in the preparation, which not only increases the cost , but also easily pollute the environment.

SUMMARY OF THE INVENTION The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art, and provide a net-like nanoporous zinc oxide micron hollow sphere with a net-like nano-sized porous structure on the spherical surface.

Another technical problem to be solved by the present invention is to provide a method for preparing network nanoporous zinc oxide micron hollow spheres which are not restricted by the shape and quality of raw materials and have a low sintering temperature.

In order to solve the technical problem of the present invention, the adopted technical scheme is: mesh nanoporous zinc oxide micron hollow spheres include zinc oxide hollow spheres, especially said zinc oxide hollow spheres are zinc oxide micron hollow spheres, and said zinc oxide micron The surfaces of the hollow spheres are mesh nanopores, wherein the diameter of the zinc oxide micron hollow spheres is 1-10 μm, and the diameter of the mesh nanoholes is 50-100 nm.

As a further improvement of the mesh nanoporous zinc oxide micron hollow spheres, the diameter of the zinc oxide micron hollow spheres is 4-6 μm.

In order to solve another technical problem of the present invention, another technical scheme that adopts is: the preparation method of reticular nanoporous zinc oxide micron hollow sphere comprises liquid-phase chemical method, particularly it is finished by following steps: (a) According to the molar ratio of zinc salt: chelating agent: sodium citrate: water = 1: 0.5~1.5: 0.05~0.15: 50~150, weigh it and put it in a container to stir and dissolve it. heat preservation for 3-10 hours to obtain the product; (b) first filter the product, wash it with water for more than one time, and then heat it at 300-500° C. for 1-3 hours to obtain a net-shaped nanoporous zinc oxide micron hollow sphere.

As a further improvement of the preparation method of mesh nanoporous zinc oxide micron hollow spheres, the zinc salt is zinc nitrate or zinc acetate or zinc chloride or zinc sulfate; the chelating agent is urea or ammonia or hexamethylene base tetramine or ammonium hydroxide; the water is deionized water or distilled water; the product is a white precipitate; after the white precipitate is filtered, the number of times of washing with water is ≤ 5 times.

Compared with the beneficial effects of the prior art, first, the prepared intermediate product and the hollow sphere are characterized by field emission scanning electron microscope and transmission electron microscope respectively, and the scanning electron microscope photo shows that the intermediate product is a very regular microsphere, and its The surface is a porous network structure connected by nanosheets. After heating and annealing at 500°C for two hours, the structure of the hollow spheres is well preserved, but the surface becomes rougher and more porous. Transmission electron micrographs show that the intermediate product is a hollow structure. The diameter of the intermediate product and the hollow sphere is 1-10 μm, and the diameter of the mesh nanopore on the surface is 50-100 nm; secondly, use an energy spectrum tester and X- X-ray diffractometer was used for characterization, and the scanning energy spectrum showed that the intermediate product contained three elements: carbon, zinc, and oxygen. After heating and annealing, there were only zinc and oxygen elements, indicating that the intermediate product was completely converted into zinc oxide. It can be seen from the X-ray diffraction pattern that the intermediate product is an amorphous material, and two weak diffraction peaks are derived from organic substances in the material. After heating and annealing in an air atmosphere at 300°C for two hours, the intermediate material begins to crystallize into a zinc oxide polycrystalline structure; third, the raw materials used in the preparation method are all chemical reagents, and the reaction is carried out in a state of atomic contact in the solution, so the quality of the product Stable, each parameter is easy to control. Through the adjustment of the reaction time, the inner and outer diameters and the overall shape of the product can be effectively controlled; Fourth, the annealing temperature is low and the energy consumption is low, resulting in lower production costs; Fifth, neither The raw materials need to be treated with acid, and organic solvents are not used, which belongs to green synthesis technology; Sixth, the method is simple and efficient, and is extremely suitable for industrial production.

As a further embodiment of the beneficial effect, the first is that the zinc salt is selected from zinc nitrate or zinc acetate or zinc chloride or zinc sulfate, and the chelating agent is selected from urea or ammonia or hexamethylenetetramine or ammonium hydroxide, so that the selection of raw materials has more advantages. Large room, not only flexible and convenient, but also beneficial to industrial production; second, after filtering the white precipitate, the number of times of washing with water is preferably ≤5 times, so that it can achieve the purpose of cleaning with less washing times.

BRIEF DESCRIPTION OF THE DRAWINGS The preferred modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is 4 pieces of SEM photographs taken after observing the intermediate product with a Japanese JEOL 6700 field emission scanning electron microscope (SEM). It can be seen from these SEM photographs that the intermediate product is a spherical powder, and the surface of the spherical object is It is a network porous structure;

Figure 2 is two SEM photographs taken after observing the prepared hollow spheres with a Japanese JEOL 6700 field emission scanning electron microscope (SEM). It can be seen from these two SEM photographs that the hollow spheres are also spherical powders. body, the surface of the sphere is also a mesh porous structure, but the surface of the sphere is rough;

Fig. 3 is the TEM photo taken after observing the intermediate product with a JEM-200CX type transmission electron microscope (TEM). As can be seen from the TEM photo, the intermediate product is a hollow sphere;

Fig. 4 is the EDS result figure that the energy spectrum test (EDS) instrument attached to the Sirion200FEG type field emission scanning electron microscope of the U.S. FEI company is used to scan the intermediate product and the hollow sphere obtained after it is scanned, wherein, (a ) The figure is the EDS result figure obtained after scanning the intermediate product, and the (b) figure is the EDS result figure obtained after the hollow sphere is scanned;

Fig. 5 is the XRD figure that obtains after testing the hollow sphere made with Japan's Rigaku X-ray diffraction (XRD) instrument, wherein, the ordinate is the relative intensity, and the abscissa is the diffraction angle, by each diffraction peak in the XRD figure It can be seen from the position and relative intensity that the micron hollow sphere is composed of zinc oxide.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT At first, make or buy zinc nitrate, zinc acetate, zinc chloride and zinc sulfate as zinc salt, urea, ammoniacal liquor, hexamethylenetetramine and ammonium hydroxide as chelating agent from the market , and sodium citrate and deionized water, distilled water. then,

Embodiment 1: complete preparation successively according to the following steps: a) according to the molar ratio of zinc salt: chelating agent: sodium citrate: water=1: 0.5: 0.15: 50, be placed in container after weighing and stir to dissolve, after sealing The product is obtained by incubating at 70° C. for 10 hours under the state; wherein zinc nitrate is selected as the zinc salt, urea is selected as the chelating agent, and deionized water is selected as the water. The product was obtained as a white precipitate. b) first filter the white precipitate, and wash it once with water to obtain the mesh nanoporous micron hollow spheres shown in Figure 1 and Figure 3 and the curve in (a) of Figure 4, and then Heating at 300° C. for 3 hours, the net-like nanoporous zinc oxide micron hollow spheres as shown in FIG. 2 and (b) of FIG. 4 and the curve in FIG. 5 were prepared.

Embodiment 2: complete preparation successively according to the following steps: a) according to the molar ratio of zinc salt: chelating agent: sodium citrate: water=1: 0.8: 0.13: 75, be placed in container and stir to dissolve after weighing, after sealing The product is obtained by incubating at 77° C. for 9 hours under the state; wherein zinc nitrate is selected as the zinc salt, urea is selected as the chelating agent, and deionized water is selected as the water. The product was obtained as a white precipitate. b) first filter the white precipitate, and wash it with water for 2 times to obtain the mesh nanoporous micron hollow spheres as shown in Figure 1 and Figure 3 and the curve in Figure 4 (a), and then Heating at 350° C. for 2.5 hours, the net-like nanoporous zinc oxide micron hollow spheres as shown in FIG. 2 and (b) of FIG. 4 and the curve in FIG. 5 were prepared.

Embodiment 3: complete preparation successively according to the following steps: a) according to the molar ratio of zinc salt: chelating agent: sodium citrate: water=1: 1: 0.1: 100, be placed in container after weighing and stir to dissolve, after sealing The product is obtained by incubating at 85° C. for 7 hours under the state; wherein zinc nitrate is selected as the zinc salt, urea is selected as the chelating agent, and deionized water is selected as the water. The product was obtained as a white precipitate. b) filter the white precipitate earlier, and wash it with water for 3 times to obtain the mesh-shaped nanoporous micron hollow spheres shown in the curve in (a) of Figure 4 as shown in Figure 1 and Figure 3, and then Heating at 400° C. for 2 hours, the net-like nanoporous zinc oxide micron hollow spheres as shown in FIG. 2 and (b) of FIG. 4 and the curve in FIG. 5 were prepared.

Embodiment 4: complete preparation successively according to the following steps: a) according to the molar ratio of zinc salt: chelating agent: sodium citrate: water=1: 1.3: 0.08: 125, be placed in container after weighing and stir to dissolve, after sealing The product is obtained by incubating at 93° C. for 5 hours under the state; wherein zinc nitrate is selected as the zinc salt, urea is selected as the chelating agent, and deionized water is selected as the water. The product was obtained as a white precipitate. b) first filter the white precipitate, and wash it with water 4 times to obtain the mesh nanoporous micron hollow spheres shown in Figure 1 and Figure 3 and curves in (a) of Figure 4, and then Heating at 450° C. for 1.5 hours, the net-like nanoporous zinc oxide micron hollow spheres as shown in FIG. 2 and (b) of FIG. 4 and the curve in FIG. 5 were prepared.

Embodiment 5: complete preparation successively according to the following steps: a) according to the molar ratio of zinc salt: chelating agent: sodium citrate: water=1: 1.5: 0.05: 150, place in container after weighing and stir to dissolve, seal The product is obtained by incubating at 100° C. for 3 hours under the state; wherein zinc nitrate is selected as the zinc salt, urea is selected as the chelating agent, and deionized water is selected as the water. The product was obtained as a white precipitate. b) first filter the white precipitate, and wash it with water for 5 times to obtain the mesh nanoporous micron hollow spheres shown in Figure 1 and Figure 3 and curves in (a) of Figure 4, and then Heating at 500° C. for 1 hour, the net-like nanoporous zinc oxide micron hollow spheres as shown in FIG. 2 and (b) of FIG. 4 and the curve in FIG. 5 were prepared. Select zinc acetate or zinc chloride or zinc sulfate in the zinc salt for use respectively, ammoniacal liquor or hexamethylenetetramine or ammonium hydroxide in the chelating agent, distilled water in water, repeat above-mentioned embodiment 1～5, make 1 to 3 and the curves in Fig. 4 and Fig. 5 show the network nanoporous micron hollow spheres and the network nanoporous zinc oxide micron hollow spheres.

Apparently, those skilled in the art can make various changes and modifications to the meshed nanoporous zinc oxide micron hollow spheres and the preparation method thereof without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (2)

1. A preparation method of reticular nanoporous zinc oxide micron hollow spheres, comprising a liquid phase chemical method, is characterized in that it is completed in the following steps: (a) According to the molar ratio of zinc salt: urea or ammonia water or hexamethylenetetramine: sodium citrate: water = 1: 0.5-1.5: 0.05-0.15: 50-150, weigh it and put it in the container to stir and dissolve , in a sealed state at 70-100°C for 3-10 hours to obtain a white precipitate; (b) First filter the white precipitate, wash it with water for more than one time, and then heat it at 300-500°C for 1-3 hours to obtain a mesh-like nanoporous zinc oxide micron hollow sphere, the mesh-like nanoporous The surface of zinc oxide micron hollow spheres is a network nanopore, the pore diameter of the network nanopore is 50-100 nm, the diameter of the hollow sphere is 1-10 μm, and the zinc salt is zinc nitrate, zinc acetate or zinc chloride or zinc sulfate, and the water is deionized water or distilled water. 2. The preparation method of the reticular nanoporous zinc oxide micron hollow sphere according to claim 1, characterized in that after the white precipitate is filtered, the number of times of washing with water is ≤ 5 times.

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