Preparation method of TiO2-coated SiO2 material

Abstract

The invention relates to a preparation method of a TiO2-coated SiO2 material, and relates to the technical field of nano materials, and the preparation method is characterized by comprising the following steps: modifying titanium dioxide nanoparticles by using CTAB (Cetyltrimethyl Ammonium Bromide), then adding TEOS (Tetraethyl Orthosilicate) into a mixture to complete a silicon dioxide coating reaction, and then calcining to obtain a densified TiO2-coated SiO2 material; cTAB (cetyltrimethylammonium bromide) is used as a template agent and a surfactant to help to form a uniform SiO2 coating layer, the dispersity of TiO2 particles in a reaction medium is improved, the agglomeration of the TiO2 particles is prevented, and the SiO2 coating layer enhances the absorption of visible light, increases the specific surface area of the material and provides more active sites, so that the photocatalytic efficiency of the material is improved.

Description

Technical Field

[0001] The invention relates to the technical field of nanomaterials, and in particular to a method for preparing a TiO2@SiO2 material. Background Art

[0002] In the development of modern science and technology, nanomaterials have been widely used in photocatalysis, environmental protection, energy conversion and other fields due to their unique physical and chemical properties. Among them, titanium dioxide (TiO2), as an important semiconductor photocatalytic material, has attracted much research and application attention due to its excellent photocatalytic performance, chemical stability and low cost. However, there are some limitations in the practical application of TiO2 materials, mainly including the following aspects: 1. Limited light response range: TiO2 has a large band gap width (about 3.2eV) and can only absorb ultraviolet light (accounting for less than 5% of the solar spectrum), which greatly limits its photocatalytic efficiency in the visible light range. 2. Photogenerated electron-hole pairs are easy to recombine: During the photocatalytic process, TiO2 is prone to recombination of photogenerated electron-hole pairs, resulting in a decrease in photocatalytic efficiency. How to effectively inhibit the recombination of photogenerated electron-hole pairs is one of the key issues in improving the photocatalytic efficiency of TiO2. 3. Particle agglomeration problem: TiO2 nanoparticles are prone to agglomeration during the dispersion process to form large particles, reducing their specific surface area and photocatalytic activity. This makes it difficult to fully utilize the performance of TiO2 in practical applications. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing a TiO2@SiO2 material to solve the problems raised in the background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a method for preparing TiO2@SiO2 material.

[0005] A method for preparing a TiO2@SiO2 material, characterized in that it comprises the following steps:

[0006] S1. Dissolve cetyltrimethylammonium bromide (CTAB) in deionized water to form a uniformly dispersed solution, then add anatase TiO2, stir with a magnetic stirrer at 30°C for 24 hours, centrifuge and wash twice to obtain anatase TiO2 modified with cetyltrimethylammonium bromide;

[0007] S2, dispersing the CTAB-modified anatase TiO2 in a mixed solution of deionized water and ethanol, and obtaining a dispersion suspension after ultrasonic treatment;

[0008] S3, using a precision pump to introduce ammonia water into the above dispersion suspension, adding tetraethyl orthosilicate (TEOS), stirring at 20°C for 12h, after the reaction is completed, centrifuging, and washing twice with ethanol and deionized water respectively;

[0009] S4. The washed material was vacuum dried at 40°C for 24 hours, and the sample was calcined at 550°C for 2 hours to obtain TiO2@SiO2 material.

[0010] Further: in step S1, the dosage ratio of CTAB, anatase TiO2 and deionized water is 0.1-0.3g:0.1-0.3g:10-80mL.

[0011] Furthermore: the particle size of anatase TiO2 in step S1 is 5-10 nm.

[0012] Furthermore: in step S2, the volume ratio of deionized water to ethanol is 1:4.

[0013] Further: in step S2, the dosage ratio of CTAB-modified anatase TiO2 and the mixed solution of deionized water and ethanol is.

[0014] Furthermore: the mass fraction of the ammonia water in step S3 is 22%-28%.

[0015] Furthermore: in step S3, the volume ratio of ammonia water to TEOS is 1:1.

[0016] Furthermore: the centrifugal time in step S1 is 10 min and the rotation speed is 10000 rpm.

[0017] Furthermore: in step S2, the ultrasonic time is 20 minutes and the frequency is 250W.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The SiO2 coating layer enhances the absorption of visible light, expands the photocatalytic response range of the material, and thus improves the photocatalytic efficiency. In addition, the TiO2@SiO2 material exhibits excellent stability and durability. The Si-O-Ti bond in the TiO2@SiO2 material is a strong covalent bond that plays an inhibitory role, can increase the structural stability of the material, and inhibit the occurrence of TiO2 phase change, thereby extending its service life, which is manifested in that the SiO2 coating layer effectively prevents the transformation of anatase TiO2 to rutile phase under high temperature environment. (2) Since both TiO2 and SiO2 are non-toxic materials, no secondary pollution will be caused to the environment during use, which meets the requirements of green environmental protection. In the process of photocatalytic degradation, the generated products are harmless and will not have a negative impact on the environment and organisms. The presence of SiO2 increases the specific surface area of ​​the material, provides more active sites, and further improves the photocatalytic efficiency. The TiO2@SiO2 composite material has good dispersibility in the solution, avoids the agglomeration of TiO2 particles, and ensures the uniformity of the photocatalytic effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 : (a) is the TEM image of TiO2@SiO2 composite material; (b) is the Mapping image of TiO2@SiO2 composite material.

[0020] Figure 2 :(1) MB degradation absorption diagram of TiO2 (1 mg / L) after different UV irradiation times;(2) MB degradation absorption diagram of TiO2@SiO2 (1 mg / L) after different UV irradiation times;(3) The ratio of the concentration of the remaining degraded substances (C) to the initial concentration (C0) during the photocatalytic degradation of TiO2 and TiO2@SiO2;(4) The photocatalytic degradation constant diagram of TiO2 and TiO2@SiO2.

[0021] Figure 3 : BET adsorption curve of TiO2@SiO2 composite material.

[0022] Figure 4 : XRD pattern of TiO2@SiO2 composite material.

[0023] Figure 5 : FTIR images of TiO2 and TiO2@SiO2 composites. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The present invention provides a technical solution: a method for preparing a TiO2@SiO2 material.

[0026] Example

[0027] S1. Dissolve 0.25 g of CTAB in 50 mL of deionized water to form a uniformly dispersed solution, add 0.25 g of anatase TiO2, stir continuously at 30 °C for 24 h with a magnetic stirrer, and obtain anatase TiO2 modified with CTAB through two centrifugation and washing cycles;

[0028] S2, dispersing 0.25 g of CTAB-modified anatase TiO2 in a mixed solution of 50 mL of deionized water and 200 mL of ethanol, and obtaining a dispersion suspension by ultrasonic treatment;

[0029] S3, using a precision pump to slowly introduce 2.5 mL of ammonia water into the above suspension, then add 2.5 mL of TEOS, and vigorously stir the mixture at 20° C. for 12 hours. After the reaction is completed, the prepared suspension is centrifuged and washed twice with ethanol and deionized water respectively;

[0030] S4. The washed material was vacuum dried at 40°C for 24 hours. Finally, the dried sample was calcined at 550°C for 2 hours to obtain a TiO2@SiO2 composite material.

[0031] The comparative example is anatase TiO2 nanoparticles with a particle size of 5-10 nm.

[0032] The examples and comparative examples were further analyzed and tested, and TEM and Mapping images of the TiO2@SiO2 composite material were taken to obtain Figure 1 It can be seen that SiO2 has been coated on the surface of TiO2 to form a uniform TiO2@SiO2 composite material. The TiO2@SiO2 composite material has good dispersibility in the solution, which avoids the agglomeration of TiO2 particles and ensures the uniformity of the photocatalytic effect.

[0033] Figure 2The absorption diagrams of MB degradation of TiO2 and TiO2@SiO2 composites after different UV irradiation times, as well as the photodegradation constant diagrams of TiO2 and TiO2@SiO2 composites, show that the SiO2 coating layer enhances the absorption of visible light, expands the photocatalytic response range of the material, and thus improves the photocatalytic efficiency.

[0034] Figure 3 N2 gas adsorption-desorption curve of TiO2@SiO2 composite material, the specific surface area reaches 376.12m 2 / g, the pore size is 2.76nm. The presence of SiO2 increases the specific surface area of ​​the material, provides more active sites, and further improves the photocatalytic efficiency.

[0035] Figure 4 This is the XRD image of the TiO2@SiO2 composite material. It can be seen that at a temperature of 1000°C, the material did not transform into the rutile phase, showing excellent thermal stability. The main reason is that the Si-O-Ti bond in the TiO2@SiO2 material plays an inhibitory role. The Si-O-Ti bond is a strong covalent bond that can increase the structural stability of the material and inhibit the occurrence of TiO2 phase change, thereby extending its service life.

[0036] Figure 5 FTIR images of TiO2 and TiO2@SiO2 composite materials, where 958 cm -1 The absorption band is Si-O-Ti bond (stretching vibration), indicating that SiO2 has been coated on the surface of TiO2 to form a uniform TiO2@SiO2 composite material.

[0037] In summary, TiO2@SiO2 composite materials have broad application prospects due to their significant advantages in photocatalytic performance, chemical stability and physical dispersibility, especially in the fields of environmental governance, energy conversion and self-cleaning materials.

[0038] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A TiO 2 @SiO 2 Methods of preparing materials, Features: The following steps are involved: S1. Dissolve hexadecyltrimethylammonium bromide in deionized water, then add anatase TiO 2 The mixture was stirred at 30 °C for 24 h using a magnetic stirrer, and centrifuged and washed twice to obtain anatase TiO2 modified with hexadecyltrimethylammonium bromide. 2 ; S2, anatase TiO modified with cetyltrimethylammonium bromide 2 Dispersed in a mixed solution of deionized water and ethanol, and subjected to ultrasonic treatment, a dispersion suspension is obtained; S3, using a precision pump to introduce ammonia water into the above dispersion suspension, adding tetraethyl orthosilicate, stirring at 20°C for 12 hours, centrifuging after the reaction, and washing twice with ethanol and deionized water respectively; S4, the washed material was vacuum dried at 40 °C for 24 h, and the sample was calcined at 550 °C for 2 h to obtain TiO 2 @SiO 2 Material.

2. A TiO according to claim 1 2 @SiO 2 Methods of preparing materials, Features: In step S1, hexadecyltrimethylammonium bromide, anatase TiO 2 The dosage ratio of deionized water is 0.1-0.3g:0.1-0.3g:10-80mL.

3. A TiO according to claim 1 2 @SiO 2 Methods of preparing materials, Features: In step S1, anatase TiO 2 The particle size is 5-10nm.

4. A TiO according to claim 1 2 @SiO 2 Methods of preparing materials, Features: The volume ratio of deionized water to ethanol in step S2 is 1:

4.

5. A TiO according to claim 1 2 @SiO 2 Methods of preparing materials, Features: In step S2, the anatase TiO2 modified with cetyltrimethylammonium bromide is 2 The dosage ratio of the mixed solution of deionized water and ethanol is 0.1-0.3g:200-250mL.

6. A TiO according to claim 1 2 @SiO 2 Methods of preparing materials, Features: The mass fraction of the ammonia water in step S3 is 22%-28%.

7. The TiO according to claim 1 2 @SiO 2 Methods of preparing materials, Features: In step S3, the volume ratio of ammonia water to tetraethyl orthosilicate is 1:

1.

8. The TiO according to claim 1 2 @SiO 2 Methods of preparing materials, Features: The centrifugal time in step S1 is 10 min and the rotation speed is 10000 rpm.

9. The TiO according to claim 1 2 @SiO 2 Methods of preparing materials, Features: The ultrasonic time in step S2 is 20 minutes and the frequency is 250W.

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