High-efficiency visible light response amorphous plasma heterojunction nano TiO2 sol

High-efficiency visible light response amorphous plasma heterojunction nano T i 02 sol technical field

[0001] The present invention belongs to the field of preparation of photocatalytic materials, and specifically relates to an amorphous plasma heterojunction nano-TiO2 sol with high-efficiency visible light response, and a preparation method and application thereof.

Background technique

[0002] With the development of society and the improvement of people's living standards, environmental pollution increasingly affects people's health, and the obvious removal effect of semiconductor TiO2 photocatalytic materials on various pollutants in the environment has attracted widespread attention in the world. Under light conditions greater than its band gap energy, the TiO2 photocatalyst can completely degrade harmful organic matter in the environment, and can also oxidize and remove toxic gases such as nitrogen oxides and sulfides in the atmosphere. In addition, the TiO2 photocatalytic material also has the functions of sterilization, deodorization, and surface self-cleaning, which can further purify and improve our living environment. However, the low utilization rate of TiO2 visible light limits its application range. In order to promote the practical application of TiO2 photocatalytic material, it is necessary to improve its photocatalytic performance and broaden its light response range. The reported solutions include: surface photosensitization, ion doping, precious metal deposition, compound semiconductors, etc. However, due to various factors, the above methods have their own shortcomings, so that the corresponding practical products have not yet appeared on the current market. .

[0003] The nano-TiO2 prepared by the present invention is a kind of non-crystalline isomorphous heterojunction nano-TiO2 sol with an effective visible light response type. The nano-particles of the sol are composed of noble metal-nano-TiO2, and other semiconductors. The heterojunction structure formed by the chemical connection between noble metal and nano-TiO2, which utilizes the Schottky junction and local surface plasmon resonance effect synergistically generated between noble metal and TiO2 semiconductor or semiconductor-noble metal and nano-TiO2 to obtain excellent The visible light photocatalytic effect solves the problem of low visible light utilization of conventional TiO2 photocatalysts.

Summary of the invention

[0004] The purpose of the present invention is to provide an amorphous plasma heterojunction nano-TiO2 sol with high efficiency visible light response and its preparation method and application. The synthesis process is simple, and the titanium dioxide particles in the prepared nano-sol are amorphous. , Good dispersibility, high efficiency visible light photocatalytic activity and good storage stability, and has good antibacterial and anti-mildew effects.

[0005] In order to achieve the above objective, the present invention adopts the following technical solutions: An amorphous plasma heterojunction nano-TiO2 sol with high efficiency visible light response, which is a combination of noble metal and nano-TiO2, or other semiconductor-noble metal and nano-TiO2 The heterojunction structure formed by chemical connection is composed of nano-particle components; the nano-TiO2 is an amorphous nano-TiO2; the noble metal includes gold, silver, pincers, nails, cobalt, rake, iron, iron or Any one of its oxides; the other semiconductors include Si02, Sn0₂, ZnO, Fe2O3, WO3, Sr (T1O3) any one or more of them.

[0006] The mass of precious metals or other semiconductor-precious metals in the sol is 0.01-2%; the mass of nano-TiO2 is 0.5-3%.

[0007] The method of the amorphous plasma heterojunction nano-TiO2 sol includes the following steps:

1) Preparation of titanium peroxide aqueous solution by liquid phase method: dissolve titanate or titanate in acidic aqueous solution under vigorous stirring, add alkali to obtain Ti (0H) 4 precipitation; After centrifugation and washing to remove impurities, stir and disperse in

In hydrogen peroxide, an aqueous solution of titanium peroxide with a mass concentration of 0.5 to 6% is prepared;

2) Preparation of amorphous nano-TiO2 sol: Add a crystal form conversion control agent to the titanium peroxide aqueous solution obtained in step 1), and heat to reflux under stirring conditions to prepare amorphous nano-TiO2 sol;

3) Preparation of amorphous plasma heterojunction nano-TiO2 sol: In step 2) the prepared amorphous nano-TiO2 sol is added a precious metal salt aqueous solution or a mixture of other semiconductor nanosols and precious metal salt aqueous solutions, and after ultrasonic dispersion, Under ultrasonic conditions, the photochemical reduction reaction is used to modify the amorphous nano-TiO2 sol with plasma heterojunction structure.

[0008] Wherein, the acidic aqueous solution in step 1) is an aqueous solution of hydrochloric acid, nitric acid or sulfuric acid with pH=1; the titanate is an organic titanate, such as tetrabutyl titanate, isopropyl titanate, etc. The titanate is an inorganic salt of titanium, such as titanium tetrachloride, titanyl sulfate, etc.; the molar concentration of the titanate or titanate in the acidic aqueous solution is 0.1 to 2 mol/L; the conditions of the hydrolysis reaction It is: temperature 0~20°C, pH value 6~10, reaction time 0.5~2 hours;

The molar ratio of Ti (0H) 4 to hydrogen peroxide is 1:20-4ο

[0009] Step 2) The molar ratio of the amount of the crystal form conversion control agent to the titanium peroxide is 0.05-2:1; the crystal form conversion control agent is nano SiO2, SnO2, ZnO, Fe2O3, WO3, Sr (TiOs ); the temperature of the heating and refluxing is 60-100°C, and the refluxing time is 1-12 hours.

[0010] In step 3), the concentration of precious metal ions in the precious metal salt aqueous solution is 1 to 3000 ppm; the precious metal salt is a precious metal chloride or a precious metal nitrate, such as ferric chloride, silver nitrate, copper nitrate, chloroauric acid, Chloric acid, etc.; The ultrasonic dispersion conditions are: ultrasonic power 400~1000W, time is 5~30min; The photochemical reduction reaction conditions are: illumination wavelength 245~400nm, illumination intensity 1~20mw/cm², The reaction temperature is 20-60 °C, and the reaction time is 0.5-2 hours.

[0011] The amorphous plasma heterojunction nano-TiO2 sol can effectively remove indoor toxic, harmful and odorous gases under visible light, purify indoor air, and can be directly coated on the surface of indoor walls, ceilings, furniture, and home accessories. In order to improve the living environment, and has the effect of antibacterial and anti-mildew.

[0012] The nano sol prepared by the present invention is an amorphous nano TiO2 sol. The optical absorption characteristics of photocatalytic materials determine the strength of their light absorption ability to a certain extent, and the light absorption characteristics of the material depend on its energy band structure, because amorphous nano-TiO2 has "short-range order, long-range no The structural characteristics of "order" make it have a different energy band structure from the crystalline nano-TiO2: there are electronic states between the valence band and the conduction band, so that the electronic transition can be between the electronic states between the valence band and the conduction band. Occurs, so that the amorphous nano-TiO2 can absorb and utilize the visible light with lower energy and longer wavelength, and excite electrons to transition between the electronic states between the valence band and the conduction band, and the electron-hole pairs formed thereby also Will participate in the photocatalytic reaction process.

[0013] The nano sol prepared by the present invention is also a plasmonic heterostructure nano TiO2 sol. Plasma photocatalyst is a kind of photocatalyst that can respond efficiently under visible light that has developed rapidly in recent years. Its constituent unit is a heterojunction structure formed by chemical connection between precious metal (and its compound) and semiconductor material, metal and semiconductor The Schottky contact formed between the two can not only promote the effective separation of photogenerated electron-hole pairs, but also provide a fast charge transfer channel that is beneficial to electron transfer, using the Schottky contact and localized surface produced by the synergy between the two Plasma resonance (LSPR) effect can obtain excellent visible light photocatalytic effects, including A, good visible light response; B, effective enhancement of light absorption; C, reduction of the diffusion distance of photogenerated electron-hole pairs; D, enhancement Local electric field effect; E, LSPR directly induced electron-hole separation; F, local heating effect; G, molecular polarization effect.

[0014] Another technical feature of the present invention is that the sol-gel method is used to prepare nanometer titanium dioxide photocatalyst solution

In the glue process, modification is carried out by introducing noble metal ions to introduce defects in the TiO2 lattice, change its crystallinity or increase its surface urn site, thereby affecting its electron-hole pair recombination and surface redox reaction. Improve its photocatalytic performance; at the same time, due to the doping of precious metal ions, the spectral absorption of nano-TiO2 produces a certain red shift, achieving the purpose of broadening its light response range; and using part of the precious metal ions (silver, copper, etc.) itself It has good antibacterial properties and can make the obtained sol possess dual antibacterial and anti-mildew properties.

[0015] The nanosol prepared by the present invention has the following advantages and positive effects:

1) The raw materials used in the present invention are cheap and easily available, especially inorganic salts of titanium.

[0016] 2) The preparation process of the present invention is simple and easy to implement, without high temperature and high pressure.

[0017] 3) The titanium dioxide particles in the nanosol prepared by the present invention are amorphous and have good dispersibility.

[0018] 4) The sol prepared by the present invention can be stored at room temperature for more than two years, its various properties remain unchanged, and it is more stable than the photocatalyst sol prepared by the conventional sol-gel method.

[0019] 5) The nanosol prepared by the present invention has obvious visible light response, and has a significant photocatalytic effect under visible light.

[0020] 6) According to GB/T 30706-2014 «Test method and evaluation of antibacterial properties of photocatalytic antibacterial materials and products under visible light irradiation» standard test conditions, the nanosol prepared by the present invention has excellent antibacterial and antifungal properties.

Description of the drawings

[0021] FIG. 1 is a TEM image of the amorphous plasma heterojunction nano-TiO2 sol prepared in Example 3.

[0022] FIG. 2 is an XRD diffraction pattern of the amorphous plasma heterojunction nano-TiO2 sol prepared in Example 3 after being dried at 50°C.

[0023] FIG. 3 is a UV-Vis diagram of the amorphous plasma heterojunction nano-TiO2 sol prepared in Example 3 and the commercially available conventional TiO2 sol.

[0024] FIG. 4 is a visible light response effect diagram of the amorphous plasma heterojunction nano-TiO2 sol prepared in Example 3 and the commercially available conventional TiO2 sol.

Detailed ways

[0025] In order to make the content of the present invention easier to understand, the technical solution of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to this.

[0026] Example 1: Preparation of aqueous titanium peroxide solution

1) Under ice-water bath conditions, 0.1 mol of TiOSCk was dropped into a strongly stirred 1000 mL pH=1 sulfuric acid aqueous solution at a rate of 1 drop/s to obtain a 0.1 mol/L TiOSCk solution;

2) Adjust the pH value of the solution to 8 with ammonia water, and centrifuge to obtain Ti(0H)4 precipitation;

3) Wash the obtained Ti(0H)4 precipitate with deionized water 10 times;

4) Disperse the washed Ti(0H) 4 precipitate in 400 mL of hydrogen peroxide solution with a mass concentration of 10% to prepare an aqueous titanium peroxide solution with a mass concentration of 2%.

[0027] Example 2: Preparation of amorphous nano-TiO2 sol: 0.5g of 30wt% nano-SiO2 aqueous dispersion (crystal form conversion control agent) was added to the 400mL aqueous titanium peroxide solution prepared in Example 1, at room temperature After stirring for 30 minutes, the solution was heated to 80°C and kept at reflux for 8 hours to prepare amorphous nano-TiO2 sol.

[0028] Example 3: Preparation of amorphous plasma heterostructure nano-TiO2 sol:

Add 4 grams of silver nitrate solution (silver particle concentration of 1000ppm) to the amorphous nano-TiO2 sol prepared in Example 2. After 600W ultrasonic dispersion for 10min, under ultrasonic conditions, at a temperature of 20°C, 400nm, light wavelength> 10mw /cm²Under the light intensity, the photochemical reduction reaction was carried out for 0.5 hours to obtain the amorphous plasma heterostructure nano-TiO2 sol.

[0029] FIG. 1 is a TEM image of the obtained amorphous plasma heterostructure nano-TiO2 sol. It can be seen from Figure 1 that the heterojunction structure nanoparticle unit of the obtained sol sample is composed of smaller nano-silver (black body) and nano-Ti02 (invisible body) interconnected internally.

[0030] FIG. 2 is an XRD pattern of the obtained amorphous plasma heterostructure nano-TiO2 sol. It can be seen from Figure 2 that the nano-TiO2 in the obtained sol sample is amorphous.

[0031] FIG. 3 is a UV-Vis diagram of the obtained amorphous plasma heterostructure nano TiO2 sol and conventional TiO2 sol, where A is a conventional TiO2 sol, and B is an amorphous plasma heterojunction nano TiO2 sol. Figure 3 shows that compared with conventional TiO2, the absorption intensity of the sol obtained in the present invention in the visible light range is significantly enhanced.

[0032] 1. Visible light response test:

1.1 Photodegradation blank prepare 250 mL 10 mg/L rhodamine B solution, stir and react for 120 min under visible light (the light intensity of the reaction liquid surface is 500 Lux), and take samples every 20 min. Use water as the control (starting Initial absorbance Αο), test the absorbance value of the solution at a wavelength of 554 nm, and obtain the absorbance Ap of the photodegradation blank reaction solution at different times;

1.2 Dark reaction prepare 250 mL reaction solution containing 10 mg/L Rhodamine B and 0.1 g effective solid component Ti02 sol, stir the reaction under dark conditions for 120 min, take samples every 20 minutes for testing, and get the reaction under dark conditions at different times The absorbance of the solution Ad;

1.3 Photodegradation reaction Prepare 250 mL of a reaction solution containing 10 mg/L of rhodamine B and 0.1 g of effective solid component Ti02 sol, and stir for 120 min under visible light (the light intensity of the reaction liquid surface is 500 Lux) for photolysis experiment. Sampling and testing every 20 minutes to obtain the absorbance Ac of the photodegradation solution at different times;

1.4 Data processing: Degradation rate = (Ap+Ad-Ac-Ao) /Aoο

[0033] According to the above method, the sol prepared in Example 3 and the conventional commercially available TiO2 sol of different well-known brands were subjected to a visible light response test.

[0034] FIG. 4 is the visible light response effect diagram of the amorphous plasma heterojunction nano-TiO2 sol prepared in Example 3 and the commercially available conventional TiO2 sol. It can be seen from Figure 4 that the amorphous plasma heterojunction nano-TiO2 sol of the present invention has a degradation rate of more than 70% for rhodamine B within 20 minutes, and a degradation rate of 97% for rhodamine B within 80 minutes. Above, it is significantly higher than conventional TiO2 sol.

[0035] 2. Antibacterial effect test: The sol prepared in Example 3 and the conventional TiO2 sol were directly coated on the surface of the glass sheet, according to GB/T 30706-2014 "Test method for antibacterial performance of photocatalytic antibacterial materials and products under visible light irradiation" And evaluation" The standard test conditions were tested separately, and the results are shown in Table 2.

[0036] Table 2 Antibacterial Test Results

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Collection of fishery mystery disc'shark Chi|Luoluxiao,: chase indigo i Jinqibo Liaoqiu dare to wrap the beak I can be seen from Table 2, under visible light conditions, the sol of the present invention has a strong antibacterial effect.

[0037] The above are only preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the scope of the patent application of the present invention should fall within the scope of the present invention.