Method for preparing black titanium dioxide through ball-milling mixing reduction

Abstract

The invention discloses a method for preparing black titanium dioxide through ball-milling mixing reduction, which comprises the following steps: by taking titanium dioxide as a raw material and trivalent titanium salt as a reducing agent, mixing the raw material and the reducing agent through ball milling to prepare the black titanium dioxide. A Ti < 3 + > defect is introduced to the surface layer of titanium dioxide by adopting a ball-milling mixing method, the visible light absorption capacity and photocatalysis are enhanced, meanwhile, the color of a titanium dioxide photocatalyst is changed by adjusting the doping amount of a reducing agent, and black titanium dioxide is successfully prepared.

Description

Technical Field

[0001] The invention relates to a method for preparing titanium dioxide, in particular to a method for preparing black titanium dioxide by ball milling mixed reduction. Background Art

[0002] Due to the increasing demand for energy, the reduction of fossil fuels and environmental degradation, the research on clean and renewable energy has gradually deepened, among which photocatalysis is a popular emerging technology in recent years. Black titanium dioxide is one of the most promising photocatalysts. It is environmentally friendly and has excellent absorption performance and high reactivity for the solar spectrum. It has broad application prospects in solar cells, photocatalytic degradation, photolysis of water to produce hydrogen and other fields.

[0003] Black titanium dioxide is a new type of photocatalyst prepared by treating common white titanium dioxide (titanium dioxide) with a special method to introduce a large number of oxygen vacancies and defects to break the symmetry of the crystal structure, change its color (white becomes a dark tone) and photoelectric properties.

[0004] Nowadays, titanium dioxide has been industrialized and mass-produced. Black titanium dioxide is prepared by hydrogenation, anodization, aluminothermic reduction and hydrothermal / solvothermal methods. Hydrogenation is the process of treating titanium dioxide in a high-temperature and high-pressure hydrogen environment to form oxygen vacancies and Ti 3+ ions, high energy consumption of equipment, uneven products and fluctuating performance; anodization generates a black titanium dioxide film in situ on the titanium metal surface by electrochemical means, which is suitable for device integration but the process is complicated; the aluminothermic reduction method generates black titanium dioxide by redox reaction of aluminum powder and titanium dioxide at high temperature. It is operated at normal pressure and has low cost, but the product purity is low and the safety risk is high; the hydrothermal method regulates the reaction of titanium source and reducing agent in high temperature and high pressure solution to introduce a large number of oxygen vacancies. This method needs to solve the problems of energy consumption and morphology control energy, or combine other methods to improve defect stability.

[0005] The above-mentioned preparation methods generally have problems such as complex process, high energy consumption, and difficulty in scale-up. In addition, some preparation methods may lead to environmental and safety risks, and there is still a gap from the actual production requirements. Therefore, it is urgent to develop a simple, green and efficient synthesis strategy to enhance the practical application potential of black titanium dioxide. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to provide a method for preparing black titanium dioxide by ball milling mixed reduction, which has a simple process, mild operating conditions and is easy to adjust the color of titanium dioxide.

[0007] Technical solution: The method for preparing black titanium dioxide by ball milling mixed reduction of the present invention uses titanium dioxide as a raw material and trivalent titanium salt as a reducing agent, and the raw material and the reducing agent are mixed by ball milling to prepare black titanium dioxide.

[0008] The mass of the reducing agent accounts for 1-15wt% of the mass of the raw material.

[0009] Wherein, the trivalent titanium salt is titanium trioxide and / or titanium trichloride.

[0010] Wherein, the titanium dioxide is anatase type or rutile type.

[0011] Among them, the ball milling method is dry method, wet method or atmosphere milling mixed; among them, dry method refers to the process of grinding materials by grinding media in a dry state; wet method refers to the addition of liquid solution, such as deionized water / anhydrous ethanol, during the ball milling process, so that the material and the grinding media interact in a liquid environment to achieve grinding and refinement; atmosphere milling refers to ball milling mixing in a specific atmosphere environment, such as an inert atmosphere or a reducing atmosphere, to prevent the material from undergoing unwanted reactions such as oxidation and hydrolysis.

[0012] Wherein, the rotation speed of the ball mill is 280-320r / min; and the time of the ball mill is 12-15h.

[0013] Principle of the invention: In the method of the present invention, titanium trioxide is used as a reducing agent to introduce Ti into TiO2. 3+ defects, this method is called "self-doping". Some of the Ti in TiO2 4+ Reduced to Ti 3+ , forming defects in the lattice, the light response of TiO2 extends from the ultraviolet region to the visible light region, thus making it have higher visible light photocatalytic activity. 3+ Defects are usually achieved by chemical reduction, heat treatment or light irradiation, while the present invention adopts a simple ball milling mixing method. Ball milling is a process of mechanically crushing and mixing materials using a high-energy ball mill. High-energy collision and extrusion impact will cause the chemical bonds inside the material to break, forming highly active intermediates. These intermediates have high reactivity and can induce reduction reactions at lower temperatures.

[0014] Beneficial effects: Compared with the prior art, the present invention has achieved the following significant effects: (1) The present invention uses titanium dioxide as raw material and titanium trioxide as a reducing agent, and introduces Ti into the surface of titanium dioxide by ball milling mixing. 3+Defects, visible light absorption capacity and photocatalysis are enhanced. At the same time, the doping amount of the reducing agent is adjusted to change the color of the titanium dioxide photocatalyst, and black titanium dioxide with different depths of color is successfully prepared. (2) Compared with the existing high-temperature hydrogenation, chemical reduction, hydrothermal reaction and other methods, the ball milling mixed reduction method of the present invention has a simple process and mild operating conditions. It does not require the use of high temperature and high pressure and hazardous chemicals, and has higher safety performance. In addition, ball milling mixing has comprehensive advantages in cost, environmental friendliness, and material performance regulation related to defect and oxygen vacancy control, particle size and dispersibility optimization, and is particularly suitable for large-scale production of industrial-grade black titanium dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 XRD patterns of black titanium dioxide prepared with different contents of reducing agent in Examples 1-3 of the present invention;

[0016] Figure 2 The scanning electron microscope images of samples prepared with different contents of reducing agents in Examples 1-3 of the present invention;

[0017] Figure 3 These are photos of samples prepared in Examples 1-6 of the present invention. DETAILED DESCRIPTION

[0018] The present invention is described in further detail below.

[0019] Example 1

[0020] (1) 10 g of titanium dioxide and 5 wt% of titanium oxide were mixed, 40 mL of deionized water was added, and wet ball milling was performed at 300 r / min for 12 h to obtain a gray-blue slurry;

[0021] (2) The slurry of step (1) is taken, dried, and ground to obtain gray-blue titanium dioxide.

[0022] Example 2

[0023] (1) 10 g of titanium dioxide and 8 wt% of titanium oxide were mixed, 40 mL of deionized water was added, and wet ball milling was performed at 300 r / min for 12 h to obtain a dark blue slurry;

[0024] (2) The slurry of step (1) is taken, dried, and ground to obtain dark blue titanium dioxide.

[0025] Example 3

[0026] (1) 10 g of titanium dioxide and 10 wt% of titanium oxide were mixed, 40 mL of deionized water was added, and wet ball milling was performed at 300 r / min for 12 h to obtain a black-blue slurry;

[0027] (2) The slurry of step (1) is taken, dried, and ground to obtain black-blue titanium dioxide.

[0028] Example 4

[0029] (1) 10 g of titanium dioxide and 5 wt% of titanium oxide were mixed and ball-milled at 300 rpm for 15 h to obtain a light grey powder;

[0030] (2) Drying and grinding the powder of step (1) to obtain light grey titanium dioxide.

[0031] Example 5

[0032] (1) 10 g of titanium dioxide and 8 wt% of titanium oxide were mixed and ball-milled at 300 r / min for 15 h to obtain a gray-blue powder;

[0033] (2) Drying and grinding the powder of step (1) to obtain gray-blue titanium dioxide.

[0034] Example 6

[0035] (1) 10 g of titanium dioxide and 10 wt% of titanium oxide were mixed and ball-milled at 300 r / min for 15 h to obtain a dark gray-blue powder;

[0036] (2) The powder of step A is dried and ground to obtain dark gray-blue titanium dioxide.

[0037] The gray-blue, dark blue, and blue-black titanium dioxide obtained in Examples 1-3 were subjected to X-ray diffraction analysis, scanning electron microscope analysis, and color analysis. The results are shown in the attached Figure 1-3 ,in, Figure 2 (a) is Example 1, (b) is Example 2, and (c) is Example 3; Figure 3 (1)-(6) are samples obtained from Examples 1-6 respectively. Figure 1-3 It is proved that the powders prepared in Examples 1-3 of the present invention are gray-blue, dark blue, and blue-black titanium dioxide respectively, belonging to the category of black titanium dioxide.

[0038] like Figure 3 As shown, by comparing the powder samples of Examples 1-3 with those of Examples 4-6, it can be seen that the powders prepared by wet ball milling are darker in color and have a higher degree of reduction than the samples prepared by dry ball milling.

[0039] Comparative Example 1

[0040] (1) Weigh 4 g of TiCl3 and 0.56 g of ascorbic acid, add 40 mL of deionized water and stir for 2 h;

[0041] (2) 1 mol / L NaOH was added to adjust the pH value and stirred for 2 h. No black solution was obtained.

[0042] (3) No black TiO2 powder was obtained after hydrothermal treatment at 180°C for 12 h.

Claims

1. A method for preparing black titanium dioxide by ball milling and mixing reduction, characterized in that: Titanium dioxide is used as a raw material, trivalent titanium salt is used as a reducing agent, and the raw material and the reducing agent are mixed by ball milling to prepare black titanium dioxide.

2. The method for preparing black titanium dioxide by ball milling and mixing reduction according to claim 1, characterized in that: The mass of the reducing agent accounts for 1-15wt% of the mass of the raw material.

3. The method for preparing black titanium dioxide by ball milling and mixing reduction according to claim 1, characterized in that: The trivalent titanium salt is titanium trioxide and / or titanium trichloride.

4. The method for preparing black titanium dioxide by ball milling and mixing reduction according to claim 1, characterized in that: The titanium dioxide is anatase type or rutile type.

5. The method for preparing black titanium dioxide by ball milling mixed reduction according to claim 1, characterized in that: The ball milling method is wet milling, dry milling or atmosphere milling.

6. The method for preparing black titanium dioxide by ball milling mixed reduction according to claim 1, characterized in that: The rotation speed of the ball mill is 280-320 r / min.

7. The method for preparing black titanium dioxide by ball milling and mixing reduction according to claim 1, characterized in that: The ball milling time is 12-15 hours.

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