CN108355693A - High Efficiency Superfine TiO2The preparation of nano particle/graphite phase carbon nitride nanometer sheet composite photo-catalyst - Google Patents

Abstract

High Efficiency Superfine TiO₂The preparation of nano particle/graphite phase carbon nitride nanometer sheet composite photo-catalyst, belongs to catalysis material technical field.With TiCl₃For titanium source, using graphite phase carbon nitride nanometer sheet as carrier, alcohol is solvent, and hydro-thermal 1 12 hours, the superfine Ti O of acquisition are carried out in 70 180 DEG C of water heating kettle₂Nano particle is equably supported on graphite phase carbon nitride nanometer sheet surface, forms composite photo-catalyst.The composite photo-catalyst has higher specific surface area and higher photocatalytic activity.The catalyst is dispersed in sewage, or coated in substrate, the pollutant in water removal and in air is effectively removed under sunlight.Therefore it can be used for building, indoor wall, surface of vehicle, the carrier surfaces such as windowpane are as automatic cleaning coating and pollutant elimination, and indoor air purification, open-air purification all has preferable effect, while also having the function of preferable antibiotic and sterilizing.

Description

High-efficiency ultrafine TiO2 nanoparticles/graphitic carbon nitride nanosheet composite photocatalyst preparation

technical field

The invention belongs to the technical field of photocatalytic materials, and in particular relates to a method for preparing a composite photocatalyst of ultrafine titanium dioxide nanoparticles/graphite-phase carbon nitride nanosheets.

Background technique

As a semiconductor material, photocatalyst can absorb sunlight and generate photogenerated electrons and holes. Photogenerated electrons have reduction characteristics and react with oxygen molecules to generate superoxide radicals. Photogenerated holes react with water molecules to generate hydroxyl radicals. , and photogenerated holes all have very strong oxidizing ability, collectively referred to as active oxygen radicals. These free radicals have a very strong oxidizing ability, which can oxidize sulfur oxides (SOx), nitrogen oxides (NOx), and volatile organic compounds (VOC) in the air, so that these pollutants can be further oxidized to achieve the purpose of air purification . In addition, this photocatalyst can be oxidized and degraded in water to remove trace organic compounds dissolved in water, such as phenyl compounds and halogen-containing compounds, and can also use photogenerated electrons to reduce heavy metals in aqueous solution and the generated active free radicals to Microbes and bacteria in stagnant water, so as to achieve the purpose of water purification. When the TiO ₂ photocatalyst is coated on the substrate, the surface of TiO ₂ becomes a super-hydrophilic surface under light irradiation, so when the liquid droplets form a water film on the surface of TiO ₂ instead of independent droplets, Combined with strong oxidation properties, it can be used as a self-cleaning coating applied to the outer surface of high-rise buildings and the surface of glass windows to play a self-cleaning role.

However, when using _TiO2 as a photocatalyst, since it can only absorb ultraviolet light, it must be under ultraviolet light to exert its photocatalytic function, while sunlight contains only 5% ultraviolet light, 40% visible light and 55% infrared light. So _TiO2 can't make full use of sunlight. Recently, Wang Xinchen et al. found that graphite-phase carbon nitride is a metal-free photocatalyst, which not only has efficient and stable photocatalytic performance, but also has photocatalytic performance in the visible light region (Nat.Mater.2009,). When two semiconductors are compounded together to form a heterostructure, due to the difference in energy levels between the two, it can promote the transfer of photogenerated charges, resulting in the spatial separation of electrons and holes, avoiding the recombination of electrons and holes, and improving photocatalysis. purpose of performance

Contents of the invention

One of the purposes of the present invention is to provide a synthetic method for ultrafine _TiO2 nanoparticle/graphitic carbon nitride composite photocatalysis, the preparation method is simple and practical, wherein the _TiO2 particle size is less than 10nm, and carbon nitride presents nanosheet Structure, high specific surface area, excellent photocatalytic performance, can be used in wastewater and waste gas treatment, indoor air purification and antibacterial materials.

To achieve the above object, the present invention adopts the following technical solutions:

A method for synthesizing ultrafine _TiO2 nanoparticles/graphitic carbon nitride, adding _TiCl3 solution to ethanol, then adding a certain amount of carbon nitride to the above solution, ultrasonically dispersing for 30 minutes, and transferring the dispersion Put it in a hydrothermal reaction kettle, react at 70-180°C for 1-12 hours, collect the light yellow precipitate generated by the reaction, then wash with ethanol, and dry to obtain a composite photocatalyst, which is characterized in that the obtained particle size is less than 10 nanometers The TiO ₂ nanoparticles were directly supported on the carbon nitride nanosheets. Moreover, the obtained catalyst has a higher specific surface area (~241m ² /g) and higher photocatalytic activity.

The crystal form of _TiO2 can be controlled as anatase crystal phase or rutile crystal phase by reaction conditions, and the rutile crystal phase or anatase crystal phase can be controlled by adding or not adding _SnCl4 aqueous solution to the reaction conditions during preparation. It is further preferably rutile phase TiO ₂ nanorods or anatase phase TiO ₂ spherical nanoparticles.

Preferably, every 1-4 ml of 15-20 wt% _TiCl3 aqueous solution is added to 60 ml of ethanol for reaction, 90-150 mg of carbon nitride nanosheets are added to the above solution, ultrasonically dispersed for 30 minutes, and then transferred to water React in a thermal reactor, keep warm at 70-180°C for 1-12 hours, collect the light yellow solid after the reaction, centrifuge, wash, and dry to obtain a composite photocatalyst of TiO ₂ spherical nanoparticles and graphite phase carbon nitride.

Preferably, every 1-4 ml of 15-20wt% TiCl _aqueous solution corresponds to 1-4 ml of 0-1M (preferably 0.5M) SnCl _aqueous solution and 60 ml of ethanol, and 90-150 mg of carbon nitride nanosheets are added to the above In the solution, ultrasonically disperse for 30 minutes, then transfer to a hydrothermal reaction kettle for reaction, keep warm at 70-180°C for 1-12 hours, collect a light yellow solid after the reaction, centrifuge, wash and dry to obtain TiO ₂ nanorods/nitrided Carbon composite photocatalyst.

The method overcomes the disadvantage that the organic titanate is expensive, and can obtain the solid powder of the titanium dioxide ultrafine nanometer particle/carbon nitride composite catalyst without complicated washing steps.

The TiO ₂ nanoparticle/graphitic carbon nitride nanosheet composite photocatalyst as the main functional component can be used to develop nano-coatings with photocatalytic activity. The catalyst is dispersed in sewage, or coated on the substrate, and effectively removes pollutants in water and air under sunlight. Therefore, it can be used in buildings, indoor walls, vehicle surfaces, glass windows and other carrier surfaces as a self-cleaning coating and pollutant elimination, indoor air purification, outdoor air purification have good effects, and also have good antibacterial properties Bactericidal effect.

The beneficial effects of the present invention are as follows:

1. The present invention provides a simple and cheap method to prepare anatase _TiO2 nanoparticles and rutile crystal phase _TiO2 nanorods and carbon nitride composite photocatalysts.

2. The TiO ₂ nanoparticles/graphitic carbon nitride nanosheets of the present invention can be used to prepare highly efficient coatings with photocatalytic properties to purify pollutants and air under sunlight or ultraviolet light.

Description of drawings

Fig. 1. is the composite catalyst obtained in embodiment 1, the XRD pattern of pure TiO nanorod and pure graphite phase carbon nitride, wherein _line 1 is rutile _TiO nanorod, and line 2 is the rutile phase that embodiment 1 obtains TiO ₂ nanorods/graphitic carbon nitride nanosheets, line 3 is pure graphitic carbon nitride.

Fig. 2 is the transmission electron microscope of the TiO _nanorod /graphite phase carbon nitride nanosheet composite catalyst obtained in Example 1.

Figure 3 is the composite catalyst obtained in Example 2, the XRD patterns of pure _TiO nanoparticles and pure graphite phase carbon nitride, in which line 1 is anatase _TiO nanoparticles, and line 2 is the anatase obtained in Example 2 Ore TiO ₂ nanoparticles/graphitic carbon nitride nanosheets, line 3 is pure graphitic carbon nitride.

Fig. 4 is the transmission electron microscope of the _{TiO2nanoparticle} obtained in Example 2 and the size distribution diagram of the nanoparticle.

Figure 5 is the nitrogen adsorption and desorption curves of _TiO2 nanorods, pure graphite phase carbon nitride nanosheets and Example 3.

Fig. 6 is the _{TiO2nanoparticle} (line 2) that embodiment 1 obtains, the _TiO2nanorod (line 3) that embodiment 3 obtains and commercialization _{P25TiO2nanoparticle} (line 1) photocatalysis under full-spectrum illumination Degradation Rhodamine B Curve. a is the change curve of rhodamine B concentration during the degradation process of rhodamine B, and b is the corresponding degradation reaction rate curve.

Figure 7 shows the comparison of samples (P25TiO ₂ , TiO ₂ nanorods, pure carbon nitride nanosheets and the composite photocatalyst in Example 3) for degradation of Rhodamine B under visible light (a) and degradation kinetics (b).

Fig. 8 is a graph showing the effect of degrading phenol under full spectrum (a) and visible light (b) compared with catalyst TiO ₂ nanorods, graphitic carbon nitride nanosheets and composite catalyst (Example 4). The composite catalysts all showed higher catalytic activity. (c) Mineralization result map of phenol, (d) is the stability test of the catalyst.

Detailed ways

In order to better illustrate the present invention, the present invention will be further described below in conjunction with the examples and accompanying drawings, but the present invention is not limited to the following examples. The preferred 15-20wt% TiCl ₃ aqueous solution is: TiCl ₃ is dissolved in 30wt% hydrochloric acid solution, and the concentration of TiCl ₃ is 15-20wt%.

Place 50 grams of urea, thiourea, dicyandiamide or melamine in a crucible, heat in a muffle furnace at a heating rate of 0.1-10°C/min, and keep at 500-600°C for 1-5 hours to obtain The solid powder is graphite phase carbon nitride.

Example 1

Preparation method of TiO _nanorod /graphitic carbon nitride nanosheet composite catalyst:

1. Add 2 milliliters of 15-20% TiCl3 aqueous solution and 1 milliliter of 0.5M _SnCl4 aqueous solution to 60 milliliters of ethanol, add 90 milligrams of carbon _nitride nanosheets to the above solution, ultrasonically disperse for 30 minutes, and then The above solution was transferred to a 100 ml hydrothermal reaction kettle, which was placed in a blast oven to raise the temperature to 100° C. and kept at 100° C. for 4 hours, and then cooled naturally.

2. Put the dispersion obtained in step 1 in a centrifuge tube, and remove the supernatant by centrifugation to obtain a solid.

3. Add 10 ml of ethanol solution to the solid obtained in step 2, sonicate until completely dispersed, remove unreacted TiCl ₃ , and then centrifuge to obtain a solid.

4. Put the solid obtained in step 3 into an oven at 70° C. for drying, and dry in the oven to obtain about 210 mg of TiO ₂ nanorod/graphite-phase carbon nitride nanosheet composite catalyst powder.

Line 1 in Fig. 1 is to obtain the XRD pattern of _TiO2 nanorod, line 3 is the XRD pattern of pure graphite phase carbon nitride, and line 2 is the XRD pattern of _TiO2 nanorod/graphite phase carbon nitride nanosheet composite catalyst , it can be seen that the obtained _TiO2 nanorods are in the rutile crystal phase. The graphitic phase carbon nitride has a lamellar structure, and the composite catalyst has typical XRD diffraction patterns of carbon nitride and rutile phase _TiO2 . Fig. 2 is the transmission electron micrograph and size distribution diagram of the obtained TiO ₂ nanorod/graphitic carbon nitride nanosheet composite catalyst. It can be seen from the low-magnification transmission electron microscope that the obtained _TiO2 is mainly rod-shaped. The diameter is 1.5 nanometers, and the rod length is about 8 nanometers. The lattice size that can be seen in the high-resolution electron microscope image is 0.324 nanometers, which is the lattice size of rutile TiO ₂ (111). This also proves that the obtained _TiO2 nanoparticles are in the rutile crystal phase. Carbon nitride has a nanosheet structure. At the same time, it can be seen that the TiO ₂ nanosheets are uniformly dispersed on the carbon nitride nanosheets without obvious aggregation.

Embodiment _2TiO The preparation method of nanoparticle/graphite phase carbon nitride nanosheet composite catalyst:

1. Add 2 ml of 15-20 wt% _TiCl3 aqueous solution into 60 ml of ethanol and stir at room temperature for 30 minutes. Then the above solution was transferred to a 100 ml hydrothermal reaction kettle, which was placed in a blast oven and heated to 100° C. and kept at 100° C. for 6 hours, and cooled naturally.

2. Put the dispersion obtained in step 1 in a centrifuge tube, and remove the supernatant by centrifugation to obtain a solid.

3. Add 10 ml of ethanol solution to the solid obtained in step 2, sonicate until completely dispersed, remove unreacted TiCl ₃ , and then centrifuge to obtain a solid.

4. Put the solid obtained in step 3 into an oven at 70° C. and dry to obtain about 200 mg of TiO ₂ nanoparticle/graphite-phase carbon nitride nanosheet composite catalyst powder.

Line 1 in Fig. 3 is to obtain the XRD pattern of _TiO2 nanoparticle, line 3 is the XRD pattern of pure graphite phase carbon nitride, and line 2 is the XRD pattern of _TiO2 nanoparticle/graphite phase carbon nitride nanosheet composite catalyst , it can be seen that the obtained _TiO2 nanoparticles are in the anatase crystal phase. The graphitic phase carbon nitride has a lamellar structure, and the composite catalyst has typical XRD diffraction patterns of carbon nitride and anatase phase _TiO2 . Fig. 4 is a transmission electron microscope image and a size distribution image of the obtained TiO ₂ nanoparticles. It can be seen that the size of the obtained TiO ₂ nanoparticles is about 2-10 nanometers, and the lattice size seen in the high-resolution electron microscope image is 0.346 nanometers, which is the lattice size of anatase TiO ₂ (101). This also proves that the obtained _TiO2 nanoparticles are anatase.

Example 3

Preparation method of _TiO2 nanorod/graphitic carbon nitride nanosheet composite catalyst

1. Add 4 milliliters of 15-20% _TiCl3 aqueous solution and 2 milliliters of 0.5M _SnCl4 aqueous solution to 60 milliliters of ethanol, add 120 milligrams of carbon nitride nanosheets to the above solution, ultrasonically disperse for 30 minutes, and then The above solution was transferred to a 100 ml hydrothermal reaction kettle, which was placed in a blast oven to raise the temperature to 100° C. and kept at 100° C. for 4 hours, and then cooled naturally. .

2. Put the dispersion obtained in step 1 in a centrifuge tube, and remove the supernatant by centrifugation to obtain a solid.

3. Add 10 ml of ethanol solution to the solid obtained in step 2, sonicate until completely dispersed, remove unreacted TiCl ₃ , and then centrifuge to obtain a solid.

4. Put the solid obtained in step 3 into an oven at 70° C. for drying, and dry in the oven to obtain about 300 mg of TiO ₂ nanorod/graphite-phase carbon nitride nanosheet composite catalyst powder.

Figure 5 is the obtained _TiO2 nanorods, graphitic carbon nitride nanosheets and the _N2 adsorption-desorption curves of the two composite catalysts, it can be seen that all the adsorption-desorption curves are typical typeIV curves, that is to say, there is an intermediate hole. Its pore size is in the range of 3-5 nanometers. The BET specific surface areas are 312m ² /g, 110m ² /g, and 241m ² /g respectively. It can be seen that the obtained TiO2 nanorod/graphitic carbon nitride has a relatively high specific surface area.

Example 4

Preparation method of _TiO2 nanorod/graphitic carbon nitride nanosheet composite catalyst

1. Add 4 milliliters of 15-20% _TiCl3 aqueous solution and 2 milliliters of 0.5M _SnCl4 aqueous solution to 60 milliliters of ethanol, add 150 milligrams of carbon nitride nanosheets to the above solution, ultrasonically disperse for 30 minutes, and then The above solution was transferred to a 100 ml hydrothermal reaction kettle, which was placed in a blast oven to raise the temperature to 120° C. and kept at 120° C. for 4 hours, and then cooled naturally.

2. Put the dispersion obtained in step 1 in a centrifuge tube, and remove the supernatant by centrifugation to obtain a solid.

3. Add 10 ml of ethanol solution to the solid obtained in step 2, sonicate until completely dispersed, remove unreacted TiCl ₃ , and then centrifuge to obtain a solid.

4. Put the solid obtained in step 3 into an oven at 70° C. for drying, and dry in the oven to obtain about 280 mg of TiO ₂ nanorod/graphite-phase carbon nitride nanosheet composite catalyst powder.

Fig. 6 is the effect diagram (a) and the degradation kinetic rate (b) of the photocatalytic degradation of rhodamine B obtained by TiO ₂ nanorods/graphitic carbon nitride. The degradation rate of the composite photocatalyst is higher than that of pure TiO ₂ and carbon nitride, which shows that the composite photocatalyst has better photocatalytic activity. Among the different ratios of _TiO2 and carbon nitride composite catalysts, the sample of Example 3 showed the best catalytic performance.

Figure 7 shows the comparison of samples (P25TiO ₂ , TiO ₂ nanorods, pure carbon nitride nanosheets and the composite photocatalyst in Example 3) for degradation of Rhodamine B under visible light (a) and degradation kinetics (b). It can be seen that the composite catalyst still shows high catalytic activity under visible light.

Fig. 8 is a graph showing the effect of degrading phenol under the full spectrum (a) and visible light (b) of the comparison catalyst TiO ₂ nanorods, graphitic carbon nitride nanosheets and composite catalysts. The composite catalysts all showed higher catalytic activity. (c) The results of mineralization of phenol, it can be seen that the composite catalyst can effectively remove organic matter in water. (d) is the stability test of the catalyst. It can be seen that the catalyst still maintains a high catalytic activity after 3 cycles of purification.

The above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Obvious changes derived on the basis of the above descriptions still fall within the protection scope of the present invention.

Claims (5)

1. a kind of _superfine TiO The synthetic method of nanoparticle/graphite phase carbon nitride nanosheet is characterized in that, TiCl solution _hydrochloric acid solution is joined in the ethanol, then adds graphite phase carbon nitride nanosheet, ultrasonic dispersion 30 Minutes, then obtain a light yellow precipitate by hydrothermal reaction, then wash with ethanol, and dry to obtain ultrafine nanoparticles. The obtained _TiO2 nanoparticles have a size less than 10 nanometers and are directly loaded on the heterographite phase carbon nitride nanosheets , to obtain a composite catalyst. 2. according to a kind of ultra _- fine TiO as claimed in claim 1 The synthetic method of nanoparticle/graphite phase carbon nitride nanosheet is characterized in that, the synthesis of graphite phase carbon nitride nanosheet: the urea of 50 grams, sulfur Urea, dicyandiamide or melamine are placed in a crucible, heated in a muffle furnace at a heating rate of 0.1-10°C/min, and kept at 500-600°C for 1-5 hours, the obtained solid powder is graphite phase nitrogen carbonized. 3. according to a kind of ultra _- fine TiO as claimed in claim 1 The synthetic method of nanoparticle/graphitic phase carbon nitride nanosheet is characterized in that, its crystal form is controlled as anatase crystal phase or rutile crystal phase by reaction condition , the anatase crystal phase or rutile crystal phase is controlled by adding or not adding SnCl ₄ aqueous solution to the reaction conditions during the preparation. 4. according to a kind of ultra _- fine TiO as claimed in claim 3 The synthetic method of nanoparticle/graphitic carbon nitride nanoplate, it is characterized in that, every 1-4 milliliter 15-20wt% TiCl _Aqueous solution is correspondingly added to 60 milliliters React in ethanol, add 90-150 mg of graphitic carbon nitride into the above solution, disperse by ultrasonic for 30 minutes, then heat the alcohol reaction at 70-180°C for 1-12 hours, centrifuge, wash and dry to obtain TiO ₂ Composite catalyst of spherical nanoparticles and carbon nitride; Or every 1-4 ml of 15-20wt% _TiCl3 aqueous solution corresponds to 1-4 ml of 0-1M (not 0) _SnCl4 aqueous solution and 60 ml of ethanol, add 90-150 mg of carbon nitride, and ultrasonically disperse for 30 minutes, Then the alcohol thermal reaction is kept at 70-180 DEG C for 1-12 hours, centrifuged, washed and dried to obtain TiO ₂ nanorods, and the obtained TiO ₂ nanorods and carbon nitride composite catalyst. 5. according to the superfine TiO that the method described in any one of claim 1-4 prepares _Nano particle and carbon nitride composite catalyst.