Preparation method of tungsten oxide nanospheres with ultra-high specific surface area

Abstract

The present invention discloses a method for preparing tungsten oxide nanospheres with ultra-high specific surface area, comprising the following steps: (1) preparing carbon nanosphere powder; (2) dispersing tungsten chloride powder and carbon nanosphere powder into an organic solvent respectively to obtain dispersion liquids, then dropwise adding the tungsten chloride dispersion liquid into the carbon nanosphere dispersion liquid to obtain a mixed liquid, and standing still; (3) centrifuging and drying the standing mixed liquid, and calcining the dried product to obtain the tungsten oxide nanosphere powder with ultra-high specific surface area. The tungsten oxide nanospheres prepared by the present invention have an ultra-high specific surface area of 500-520 m2 / g, which is much higher than that of mesoporous tungsten oxide with a specific surface area below 200 m2 / g reported in the prior art; the preparation process is simple, the conditions are mild, and the repeatability is good; it has good specific capacitance and has broad application prospects in the fields such as supercapacitors.

Description

Technical Field

[0001] The present invention relates to a method for preparing nano-oxide spheres, and particularly to a method for preparing tungsten oxide nano-spheres with a super-high specific surface area. Background Art

[0002] Tungsten oxide is a novel semiconductor material with a special tunnel structure, multiple oxidation states, and good chemical stability. It has been widely used in the fields of optics, catalysis, energy storage, gas detection, etc. (Huang Z F, Song J, Pan L, et al. Tungsten oxides for photocatalysis, electrochemistry, and phototherapy [J]. Advanced Materials, 2015, 27(36): 5309 - 27). The specific surface area has a significant impact on the performance of tungsten oxide. In the field of energy storage, tungsten oxide electrodes with a high specific surface area have more excellent specific capacitance (Shinde P A, Jun SC. Review on recent progress in the development of tungsten oxide based electrodes for electrochemical energy storage [J]. ChemSusChem, 2020, 13(1): 11 - 38). In the field of industrial production, tungsten oxide with a high specific surface area has excellent chemical activity and a fast reduction rate, which is not only beneficial to the preparation of doped tungsten wires but also can significantly improve the production efficiency of tungsten powder (Schubert W D, Lassner E. Production and characterization of hydrogen-reduced submicron tungsten powders—Part 1: State of the art in research, production and characterization of raw materials and tungsten powders [J]. International Journal of Refractory Metals and Hard Materials, 1991, 10(3): 133 - 41).

[0003] Currently, the synthesis method of tungsten oxide is mainly solvothermal. This method requires high-temperature and high-pressure conditions during the preparation process, and the obtained morphology is uncontrollable. The specific surface area is mostly around 200 m 2 / g or less (Novakt G, Kim J, Desario P A, et al. Synthesis and applications of WO3 nanosheets: the importance of phase, stoichiometry, and aspect ratio [J]. Nanoscale Advances, 2021, 3(18): 5166 - 82).

[0004] Therefore, reasonably regulating the synthesis conditions of tungsten oxide to prepare tungsten oxide with a high specific surface area is of great significance for the industrial application of tungsten oxide. Summary of the Invention

[0005] Object of the Invention: The object of the present invention is to provide a method for preparing tungsten oxide nanospheres with an ultra - high specific surface area, which has a simple process and mild conditions.

[0006] Technical Solution: The method for preparing tungsten oxide nanospheres with an ultra - high specific surface area according to the present invention includes the following steps:

[0007] (1) Prepare carbon nanosphere powder;

[0008] (2) Disperse tungsten chloride powder and carbon nanosphere powder into an organic solvent respectively to obtain dispersions, then dropwise add the tungsten chloride dispersion into the carbon nanosphere dispersion to obtain a mixed solution, and let it stand;

[0009] (3) Centrifuge and dry the mixed solution after standing, and calcine the dried product to obtain the tungsten oxide nanosphere powder with an ultra - high specific surface area.

[0010] Among them, in step (1), the carbon nanosphere powder is prepared by hydrothermal treatment of a carbon source; the hydrothermal temperature is 180 - 220 °C, and the time is 8 - 10 h; at the above temperature and time, carbon nanospheres with a diameter of 100 - 200 nm and uniform size are prepared.

[0011] Among them, in step (1), the carbon source is at least one of glucose, dopamine hydrochloride, or aniline.

[0012] Among them, in step (2), the organic solvent is at least one of dimethylformamide, acetonitrile, or dimethylaniline.

[0013] Among them, in step (2), the standing temperature is 25 - 60 °C, and the standing time is 24 - 48 h. At the above temperature and time, tungsten chloride and carbon nanospheres form a good coating.

[0014] Among them, in step (3), the calcination temperature is 450 - 650 °C, and the heat preservation time is 2 - 6 h. At the above temperature and time, the carbon nanospheres decompose, and tungsten chloride is converted into tungsten oxide nanospheres.

[0015] The diameter of the tungsten oxide nanospheres prepared by the above method is 50 - 60 nm, the specific surface area is as high as 500 - 520 m 2 / g, and the pore volume is 0.07 - 0.1 cm 3 / g.

[0016] Principle of the invention: Tungsten chloride is selected as the tungsten precursor in the present invention. The tungsten cations in tungsten chloride are attracted to the hydroxyl groups on the surface of the carbon nanospheres, achieving a good coating effect, avoiding the agglomeration of tungsten oxide, and being beneficial to obtaining a morphology with a regular pore structure and a high specific surface area. One or more of dimethylformamide, acetonitrile, and dimethylaniline are selected as the solvent in the present invention, and the hydrolysis of the tungsten precursor can be effectively slowed down through coordination, thereby avoiding the destruction of the tungsten oxide morphology and the decrease in specific surface area. By selecting dimethylformamide with stronger coordination ability as the solvent, the morphology of tungsten oxide can be further stabilized and the specific surface area can be increased.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following remarkable effects: (1) The tungsten oxide nanospheres prepared by the present invention have an ultra-high specific surface area of 500 - 520 m 2 / g, which is much higher than the mesoporous tungsten oxide with a specific surface area reported in the prior art of less than 200 m 2 / g; the preparation process is simple, the conditions are mild, and the repeatability is good. (2) The ultra-high specific surface area tungsten oxide nanospheres prepared by the present invention have good specific capacitance and have broad application prospects in the fields such as supercapacitors. Description of the drawings

[0018] Figure 1 It is the XRD diffraction pattern of the ultra-high specific surface area tungsten oxide nanospheres prepared in Example 1;

[0019] Figure 2 It is the TEM image of the ultra-high specific surface area tungsten oxide nanospheres prepared in Example 1;

[0020] Figure 3 It is the nitrogen adsorption - desorption curve and pore size distribution curve of the ultra-high specific surface area tungsten oxide nanospheres prepared in Example 1;

[0021] Figure 4 It is the specific capacitance of the ultra-high specific surface area tungsten oxide nanospheres prepared in Example 1 at different current densities. Specific implementation manners

[0022] The present invention will be further described in detail below.

[0023] Example 1

[0024] For the ultra-high specific surface area tungsten oxide nanospheres of this example, the preparation method is as follows:

[0025] (1) Dissolve 7.2 g of glucose in deionized water, transfer it to a hydrothermal reactor and react at 180 °C for 8 h. Then centrifuge the brown product at 8000 rpm, wash it with deionized water and dry it at 80 °C for 12 h to obtain carbon nanosphere powder;

[0026] (2) Disperse tungsten chloride powder and carbon nanosphere powder into dimethylformamide respectively to obtain dispersions. Then gradually add 0.4 mmol / L tungsten chloride dispersion dropwise to 0.02 mol / L carbon nanosphere dispersion, and let the mixed solution stand at 25 °C for 24 h;

[0027] (3) Centrifuge the mixed solution at 10000 rpm, transfer the obtained black product to a tube furnace after drying at 80 °C for 12 h, heat it up to 450 °C and calcine it for 2 h to obtain tungsten oxide nanosphere powder with ultra-high specific surface area.

[0028] Figure 1 is the XRD diffraction pattern of the ultra-high specific surface area tungsten oxide nanospheres prepared in this example. It can be seen from the figure that the diffraction peaks of orthorhombic tungsten oxide (001), (020) and (200) crystal planes (JCPDS No.: 20-1324) are prepared by the method of Example 1.

[0029] Figure 2 is the TEM image of the ultra-high specific surface area tungsten oxide nanospheres prepared in this example. It can be seen from the figure that tungsten oxide presents a porous nanosphere structure with a diameter of 50-60 nm.

[0030] Figure 3 is the nitrogen adsorption-desorption curve and pore size distribution curve of the ultra-high specific surface area tungsten oxide nanospheres prepared in this example. It can be seen from the figure that the tungsten oxide nanospheres have a uniform pore structure and the pore size is concentrated at 0.6 nm. Further calculated by the BJH method, the specific surface area of the tungsten oxide nanospheres is as high as 520 m 2 / g, and the pore volume is 0.1 cm 3 / g.

[0031] Figure 4 is the specific capacitance of the ultra-high specific surface area tungsten oxide nanospheres prepared in this example at different current densities. It can be seen from the figure that at a current density of 1 A / g, the specific capacitance of the ultra-high specific surface area tungsten oxide nanospheres can reach 205 F / g, indicating that the tungsten oxide nanospheres prepared by the present invention have broad application potential in the field of supercapacitors.

[0032] Example 2

[0033] For the ultra-high specific surface area tungsten oxide nanospheres of this embodiment, the preparation method is as follows:

[0034] (1) Dissolve 7.2 g of glucose in deionized water, transfer it to a hydrothermal autoclave and react at 180 °C for 8 h. Then centrifuge the brown product at 8000 rpm, wash it with deionized water and dry it at 80 °C for 12 h to obtain carbon nanosphere powder;

[0035] (2) Disperse tungsten chloride powder and carbon nanosphere powder into dimethylformamide to obtain dispersions respectively. Then dropwise add the 0.4 mmol / L tungsten chloride dispersion into the 0.02 mol / L carbon nanosphere dispersion, and let the mixed solution stand at 25 °C for 24 h;

[0036] (3) Centrifuge the mixed solution at 10000 rpm, transfer the obtained black product to a tube furnace after drying at 100 °C for 12 h, heat it up to 550 °C and calcine for 4 h to obtain tungsten oxide nanosphere powder with ultra-high specific surface area.

[0037] The specific surface area of the ultra-high specific surface area tungsten oxide prepared in this embodiment reaches 500 m 2 / g, and the pore volume is 0.07 cm 3 / g.

[0038] Example 3

[0039] For the ultra-high specific surface area tungsten oxide nanospheres of this embodiment, the preparation method is as follows:

[0040] (1) Dissolve 21.6 g of aniline in deionized water, transfer it to a hydrothermal autoclave and react at 220 °C for 10 h. Then centrifuge the brown product at 5000 rpm, wash it with deionized water and dry it at 80 °C for 24 h to obtain carbon nanosphere powder;

[0041] (2) Disperse tungsten chloride powder and carbon nanosphere powder into dimethylaniline to obtain dispersions respectively. Then dropwise add the 0.4 mmol / L tungsten chloride dispersion into the 0.02 mol / L carbon nanosphere dispersion, and let the mixed solution stand at 60 °C for 24 h;

[0042] (3) Centrifuge the mixed solution at 5000 rpm, transfer the obtained black product to a tube furnace after drying at 100 °C for 12 h, heat it up to 650 °C and calcine for 4 h to obtain tungsten oxide nanosphere powder with ultra-high specific surface area.

[0043] Example 4

[0044] For the ultra-high specific surface area tungsten oxide nanospheres of this embodiment, the preparation method is as follows:

[0045] (1) Dissolve 21.6 g of dopamine hydrochloride in deionized water, transfer it to a hydrothermal reactor and react at 220 °C for 10 h. Then centrifuge the brown product at 8000 rpm, wash it with deionized water and dry it at 100 °C for 24 h to obtain carbon nanosphere powder;

[0046] (2) Disperse tungsten chloride powder and carbon nanosphere powder into acetonitrile respectively to obtain dispersions. Then dropwise add 0.4 mmol / L tungsten chloride dispersion into 0.02 mol / L carbon nanosphere dispersion, and let the mixed solution stand at 60 °C for 48 h;

[0047] (3) Centrifuge the mixed solution at 5000 rpm, transfer the obtained black product to a tube furnace after drying at 100 °C for 12 h, heat it up to 650 °C and calcine for 6 h to obtain tungsten oxide nanosphere powder with ultra-high specific surface area.

[0048] Comparative Example 1

[0049] The tungsten oxide nanospheres in this comparative example were prepared as follows:

[0050] (1) Dissolve 7.2 g of glucose in deionized water, transfer it to a hydrothermal reactor and react at 180 °C for 8 h. Then centrifuge the brown product at 8000 rpm, wash it with deionized water and dry it at 80 °C for 12 h to obtain carbon nanosphere powder;

[0051] (2) Disperse tungsten chloride powder and carbon nanosphere powder into ethanol respectively to obtain dispersions. Then dropwise add 0.4 mmol / L tungsten chloride dispersion into 0.02 mol / L carbon nanosphere dispersion, and let the mixed solution stand at 25 °C for 24 h;

[0052] (3) Centrifuge the mixed solution at 10000 rpm, transfer the obtained black product to a tube furnace after drying at 80 °C for 12 h, heat it up to 450 °C and calcine for 2 h to obtain tungsten oxide nanosphere powder.

[0053] Figure 3 The nitrogen adsorption-desorption isotherm and pore size distribution curve of the tungsten oxide nanospheres prepared in this comparative example are shown. Calculated by the BJH method, the specific surface area of the tungsten oxide nanospheres in this comparative example is 33 m 2 / g, and the pore volume is 2.1 cm 3 / mg.

[0054] Figure 4 The specific capacitance of the tungsten oxide nanospheres prepared in this comparative example at different current densities is shown. It can be seen from the figure that at a current density of 1 A / g, the specific capacitance of the tungsten oxide nanospheres in this comparative example is 134 F / g.

Claims

1. A method for preparing tungsten oxide nanospheres with ultra-high specific surface area, characterized in that, It includes the following steps: (1) Prepare carbon nanosphere powder; (2) Disperse tungsten chloride powder and carbon nanosphere powder into an organic solvent respectively to obtain a dispersion liquid, then dropwise add the tungsten chloride dispersion liquid into the carbon nanosphere dispersion liquid to obtain a mixed liquid, and let it stand; the concentration of the tungsten chloride dispersion liquid is 0.4 - 0.8 mmol / L; the concentration of the carbon nanosphere dispersion liquid is 0.02 - 0.05 mol / L; the temperature for standing is 25 - 60 °C, and the time for standing is 24 - 48 h; the organic solvent is at least one of dimethylformamide, acetonitrile, and dimethylaniline; (3) Centrifuge and dry the mixed solution after standing still, and calcine the dried product to obtain the ultra-high specific surface area tungsten oxide nanosphere powder; the specific surface area of the tungsten oxide nanosphere is 500-520 m 2 / g.

2. The preparation method of the tungsten oxide nanospheres with ultra-high specific surface area according to claim 1, wherein In step (1), the carbon source is prepared into carbon nanosphere powder under hydrothermal conditions.

3. The preparation method of the ultra-high specific surface area tungsten oxide nanospheres according to claim 2, wherein, The temperature of the hydrothermal process is 180 - 220 °C, and the time is 8 - 10 h.

4. The preparation method of the ultra-high specific surface area tungsten oxide nanospheres according to claim 2, characterized in that, The carbon source is at least one of glucose, dopamine hydrochloride, and aniline.

5. The preparation method of a tungsten oxide nanosphere with an ultra-high specific surface area according to claim 1, characterized in that, In step (3), the calcination temperature is 450 - 650 °C, and the heat preservation time is 2 - 6 h.

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