Graphene reinforced photocatalyst material and preparation method thereof

Abstract

The invention provides a graphene reinforced photocatalyst material and a preparation method thereof, and belongs to the technical field of photocatalysts. Comprising the following steps: S1, dissolving silver nitrate and copper salt in a graphene oxide aqueous dispersion to prepare an Ag / Cu doped graphene oxide dispersion; s2, dissolving tetrabutyl titanate and zinc acetate in water, adding citric acid, melamine and ethylene glycol, stirring and mixing uniformly, dropwise adding concentrated hydrochloric acid, stirring and reacting, and calcining to prepare a doped TiO2 / ZnO compound; s3, adding the doped TiO2 / ZnO compound into the Ag / Cu doped graphene oxide dispersion liquid, and performing spray drying to obtain a compound; s4, the compound is subjected to hydrazine hydrate steam reduction, and the graphene enhanced photocatalyst material is prepared and has the advantages that the good utilization effect on visible light is achieved, the adsorption rate on pollutants is increased, and catalytic active sites are increased, so that the photocatalytic antibacterial and organic matter degradation effects are obviously enhanced, and wide application prospects are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysts, and in particular to a graphene-enhanced photocatalyst material and a preparation method thereof. Background Art

[0002] Photocatalytic purification materials are materials that, under the action of a certain light source, electrons in the valence band (e - ) jumps to the conduction band, generating corresponding holes (h + ), generating superoxide ion free radicals, hydroxyl free radicals, and superoxide hydroxyl free radicals with extremely strong oxidizing effects, which can oxidize and decompose formaldehyde, benzene, toluene, xylene, ammonia, VOC and other toxic and harmful gas pollutants, odors, bacteria, etc. into harmless CO2 and H2O, and have high-efficiency and broad-spectrum disinfection performance, and have a good inhibitory and killing effect on various common pathogens.

[0003] But traditional photocatalytic materials only have high quantum conversion efficiency at the nanometer size, and the smaller the size of the nanomaterial, the higher its photocatalytic efficiency. For example, the degradation efficiency of P5 (the average particle size of the particles is about 5nm) particles in solution for methyl blue is much better than that of P25 (the average particle size of the particles is about 21nm, belonging to the mixed crystal type, anatase and rutile crystal type) particles. However, P5 or smaller photocatalytic particles cannot be used directly in the air. They will be suspended in the air and will disappear when the wind blows. At the same time, traditional photocatalytic materials are difficult to bond with other materials, have small reaction active points, increase the probability of recombination of holes and electrons, have a short lifespan, and can only use ultraviolet light.

[0004] Graphene has a two-dimensional honeycomb crystal structure formed by the close stacking of a single layer of carbon atoms. The unique and perfect structure of graphene gives it excellent electrical, mechanical, thermal and optical properties. Since there are many dangling bonds on the surface of graphene, it can be well bonded with the photocatalytic material. Secondly, graphene has a large specific surface area and high electron mobility, which increases the active points of the reaction, while reducing the recombination of electrons and holes, improving the photocatalytic efficiency. In addition, the presence of graphene narrows the band gap of the titanium dioxide photocatalytic material and increases the utilization rate of sunlight. Therefore, the photocatalytic efficiency can be improved by effectively compounding graphene and titanium dioxide photocatalytic materials. However, the specific surface area of ​​the graphene and titanium dioxide composite photocatalytic materials disclosed now is limited, and in the actual application of air purification, the composite photocatalytic material needs to be loaded on a substrate for use, the loading amount of the substrate is limited, and the contact area and contact time of the composite photocatalytic material on the substrate when the air passes through the purification device once are limited, and the composite photocatalytic material cannot completely and quickly degrade harmful substances such as bacteria and viruses in the air. Therefore, in order to broaden the practical application of composite photocatalytic materials, it is still necessary to develop a graphene and titanium dioxide composite photocatalytic material with a large specific surface area and higher photocatalytic efficiency.

[0005] Patent application No. 201010590547.3 discloses a graphene / nano-titanium dioxide composite and a preparation method thereof, wherein nano-titanium dioxide and graphene are dispersed in a water / ethanol solution of a certain proportion, and the nano-titanium dioxide and graphene in the dispersion are reacted by pressurizing and heating.

[0006] Patent application No. 201110225465.3 discloses a graphene / mesoporous titanium dioxide visible light catalyst and a preparation method thereof, wherein graphene oxide is added to glacial acetic acid and ultrasonically dispersed to obtain a dispersion of graphene oxide; a titanium source is added to the dispersion of graphene oxide and a graphene / mesoporous titanium dioxide nanocomposite visible light catalyst is prepared by a hydrothermal method.

[0007] Patent application No. 201210582986.9 discloses a method for preparing a graphene / titanium dioxide photocatalyst, wherein graphene oxide is added to a mixed solution of water and ethanol, the mixed solution is then added dropwise to chloroform containing tetrabutyl titanate, and the final mixed solution is reacted in a hydrothermal autoclave to prepare a graphene / titanium dioxide photocatalyst.

[0008] Patent application No. 201310287749.4 discloses a method for preparing a graphene and titanium dioxide composite material, wherein a precursor containing titanium ions is dissolved in anhydrous ethanol to prepare a solution, and then a graphene oxide solution is added, deposited, dried, and then the graphene and titanium dioxide composite material is obtained by a hydrothermal method.

[0009] However, although the composite material obtained by the above method can enable titanium dioxide to utilize the visible light region to a certain extent, the effect is not good. Summary of the invention

[0010] The purpose of the present invention is to provide a graphene-enhanced photocatalyst material and a preparation method thereof, which has a good utilization effect on visible light, improves the adsorption rate of pollutants, and increases the catalytic active sites, thereby significantly enhancing the photocatalytic antibacterial and organic matter degradation effects, and has broad application prospects.

[0011] The technical solution of the present invention is achieved in this way: The present invention provides a method for preparing a graphene enhanced photocatalyst material, comprising the following steps: S1. Dissolving silver nitrate and copper salt in an aqueous dispersion of graphene oxide to obtain an Ag / Cu-doped graphene oxide dispersion; S2. The tetrabutyl titanate and zinc acetate were dissolved in water, citric acid, melamine and ethylene glycol were added, the mixture was stirred and mixed, concentrated hydrochloric acid was added dropwise, the reaction was stirred, centrifuged, washed, dried and calcined to obtain a doped TiO2 / ZnO composite; S3. The doped TiO2 / ZnO composite was added to the Ag / Cu doped graphene oxide dispersion and spray dried to obtain a composite; S4. The composite is reduced with hydrazine hydrate vapor to obtain a graphene-enhanced photocatalyst material.

[0012] As a further improvement of the present invention, the mass ratio of the silver nitrate, the copper salt and the graphene oxide aqueous dispersion in step S1 is 1-3:3-5:30-50.

[0013] As a further improvement of the present invention, the concentration of the graphene oxide aqueous dispersion in step S1 is 0.1-0.2 mg / mL, and the copper salt is selected from at least one of copper chloride, copper sulfate, and copper nitrate.

[0014] As a further improvement of the present invention, the mass ratio of tetrabutyl titanate, zinc acetate, citric acid, melamine and ethylene glycol in step S2 is 10-15:7-10:12-15:1-3:5-10.

[0015] As a further improvement of the present invention, in step S2, concentrated hydrochloric acid is added dropwise to adjust the pH value of the solution to 3-5.

[0016] As a further improvement of the present invention, the stirring reaction time in step S2 is 3-5 hours.

[0017] As a further improvement of the present invention, the calcination temperature in step S2 is 500-600° C. and the calcination time is 2-4 hours.

[0018] As a further improvement of the present invention, the solid-to-liquid ratio of the doped TiO2 / ZnO composite and the Ag / Cu doped graphene oxide dispersion in step S3 is 1:3-5 g / mL.

[0019] As a further improvement of the present invention, the time for the hydrazine hydrate steam reduction in step S4 is 5-7 hours.

[0020] The present invention further protects a graphene enhanced photocatalyst material prepared by the above preparation method.

[0021] The present invention has the following beneficial effects: In the graphene-enhanced photocatalyst material prepared by the present invention, the electron mobility of graphene is extremely high, and it can be used as a conductive substrate of the photocatalyst material, significantly improving the separation efficiency of photogenerated electron-hole pairs, reducing the recombination probability, thereby enhancing the photocatalytic activity. By compounding graphene with titanium dioxide (TiO2), an efficient electron transmission channel can be constructed to extend the carrier life. In addition, the high specific surface area of ​​graphene can provide more active sites for the photocatalyst, enhance the adsorption capacity of pollutants or reactants, and improve the catalytic efficiency.

[0022] The present invention introduces oxygen vacancies and metal nanoparticles (including Ag and Cu) into graphene oxide, which can regulate its energy band structure, expand the light response range of titanium dioxide in the photocatalyst to visible light and even infrared bands, and improve the utilization rate of sunlight.

[0023] The doped TiO2 / ZnO composite of the present invention is doped with S and N to form a composite. Sulfur (S) and nitrogen (N) doping can introduce new impurity energy levels in the TiO2 lattice (such as the formation of Ti-OSN bonds), which significantly reduces the band gap of TiO2 and significantly improves the absorption capacity of visible light. In addition, the heterojunction interface (such as ZnO / S-TiO2) formed by the composite of ZnO and NS-TiO2 forms a built-in electric field through energy band matching, which accelerates the migration of photogenerated electrons from the ZnO conduction band to the S-TiO2 conduction band, and at the same time, the holes migrate in the opposite direction, effectively suppressing the electron-hole recombination and improving the quantum efficiency.

[0024] The graphene-enhanced photocatalyst material prepared by the present invention has a good utilization effect on visible light, improves the adsorption rate of pollutants, and increases the catalytic active sites, thereby significantly enhancing the effects of photocatalytic antibacterial and degradation of organic matter, and has broad application prospects. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0026] Graphene oxide aqueous dispersion, single layer, original concentration is 0.5 mg / mL, added with pure water to prepare different concentrations, commercially available. Example 1

[0027] This embodiment provides a method for preparing a graphene enhanced photocatalyst material, comprising the following steps: S1. 1 g of silver nitrate and 3 g of copper nitrate were dissolved in 30 g of 0.1 mg / mL of graphene oxide aqueous dispersion to prepare Ag / Cu doped graphene oxide dispersion; S2. Dissolve 10 g of tetrabutyl titanate and 7 g of zinc acetate in 500 mL of water, add 12 g of citric acid, 1 g of melamine and 5 g of ethylene glycol, stir and mix for 15 min, add concentrated hydrochloric acid dropwise to adjust the pH value of the solution to 3, stir and react for 3 h, centrifuge, wash, dry, and calcine at 500 ° C for 2 h to obtain a doped TiO2 / ZnO composite; S3. 10 g of the doped TiO2 / ZnO composite was added to 30 mL of Ag / Cu doped graphene oxide dispersion and spray dried to obtain a composite; S4. The composite is reduced with hydrazine hydrate vapor for 5 hours to obtain a graphene-enhanced photocatalyst material. Example 2

[0028] This embodiment provides a method for preparing a graphene enhanced photocatalyst material, comprising the following steps: S1. 3 g of silver nitrate and 5 g of copper sulfate were dissolved in 50 g of 0.2 mg / mL of graphene oxide aqueous dispersion to obtain Ag / Cu doped graphene oxide dispersion; S2. Dissolve 15g of tetrabutyl titanate and 10g of zinc acetate in 500mL of water, add 15g of citric acid, 3g of melamine and 10g of ethylene glycol, stir and mix for 15min, add concentrated hydrochloric acid dropwise to adjust the pH value of the solution to 5, stir and react for 5h, centrifuge, wash, dry, and calcine at 600℃ for 4h to obtain a doped TiO2 / ZnO composite; S3. 10 g of the doped TiO2 / ZnO composite was added to 50 mL of Ag / Cu doped graphene oxide dispersion and spray dried to obtain a composite; S4. The composite is reduced with hydrazine hydrate vapor for 7 hours to obtain a graphene-enhanced photocatalyst material. Example 3

[0029] This embodiment provides a method for preparing a graphene enhanced photocatalyst material, comprising the following steps: S1. 2 g of silver nitrate and 4 g of copper chloride were dissolved in 40 g of 0.15 mg / mL of graphene oxide aqueous dispersion to obtain Ag / Cu doped graphene oxide dispersion; S2. 12 g of tetrabutyl titanate and 8 g of zinc acetate were dissolved in 500 mL of water, 13 g of citric acid, 2 g of melamine and 7 g of ethylene glycol were added, and the mixture was stirred for 15 min, concentrated hydrochloric acid was added dropwise to adjust the pH value of the solution to 4, and the mixture was stirred for 4 h, centrifuged, washed, dried, and calcined at 550 ° C for 3 h to obtain a doped TiO2 / ZnO composite; S3. 10 g of the doped TiO2 / ZnO composite was added to 40 mL of Ag / Cu-doped graphene oxide dispersion and spray dried to obtain a composite; S4. The composite was reduced with hydrazine hydrate vapor for 6 hours to obtain a graphene-enhanced photocatalyst material.

[0030] Comparative Example 1 Compared with Example 3, the difference is that silver nitrate and copper nitrate are not added in step S1.

[0031] The details are as follows: S1. Dissolve 12g of tetrabutyl titanate and 8g of zinc acetate in 500mL of water, add 13g of citric acid, 2g of melamine and 7g of ethylene glycol, stir and mix for 15min, add concentrated hydrochloric acid dropwise to adjust the pH value of the solution to 4, stir and react for 4h, centrifuge, wash, dry, and calcine at 550℃ for 3h to obtain a doped TiO2 / ZnO composite; S2. 10 g of the doped TiO2 / ZnO composite was added to 40 mL of a 0.15 mg / mL aqueous dispersion of graphene oxide and spray dried to obtain a composite; S3. The composite was reduced with hydrazine hydrate vapor for 6 hours to obtain a graphene enhanced photocatalyst material.

[0032] Comparative Example 2 Compared with Example 3, the difference is that melamine is not added in step S2.

[0033] The details are as follows: S1. 2 g of silver nitrate and 4 g of copper chloride were dissolved in 40 g of 0.15 mg / mL of graphene oxide aqueous dispersion to obtain Ag / Cu doped graphene oxide dispersion; S2. 12 g of tetrabutyl titanate and 8 g of zinc acetate were dissolved in 500 mL of water, 13 g of citric acid and 7 g of ethylene glycol were added, and the mixture was stirred for 15 min, concentrated hydrochloric acid was added dropwise to adjust the pH value of the solution to 4, and the mixture was stirred for 4 h, centrifuged, washed, dried, and calcined at 550 ° C for 3 h to obtain a TiO2 / ZnO composite; S3. 10 g of TiO2 / ZnO composite was added to 40 mL of Ag / Cu doped graphene oxide dispersion and spray dried to obtain a composite; S4. The composite was reduced with hydrazine hydrate vapor for 6 hours to obtain a graphene-enhanced photocatalyst material.

[0034] Comparative Example 3 Compared with Example 3, the difference is that zinc acetate is not added in step S2.

[0035] The details are as follows: S1. 2 g of silver nitrate and 4 g of copper chloride were dissolved in 40 g of 0.15 mg / mL of graphene oxide aqueous dispersion to obtain Ag / Cu doped graphene oxide dispersion; S2. 12 g of tetrabutyl titanate was dissolved in 500 mL of water, 13 g of citric acid, 2 g of melamine and 7 g of ethylene glycol were added, and the mixture was stirred for 15 min, concentrated hydrochloric acid was added dropwise to adjust the pH value of the solution to 4, and the mixture was stirred for 4 h, centrifuged, washed, dried, and calcined at 550 ° C for 3 h to obtain a doped TiO2 composite; S3. 10 g of the doped TiO2 composite was added to 40 mL of Ag / Cu-doped graphene oxide dispersion and spray dried to obtain a composite; S4. The composite was reduced with hydrazine hydrate vapor for 6 hours to obtain a graphene-enhanced photocatalyst material.

[0036] Comparative Example 4 Compared with embodiment 3, the difference is that only step S2 is included.

[0037] The details are as follows: Dissolve 12 g of tetrabutyl titanate and 8 g of zinc acetate in 500 mL of water, add 13 g of citric acid, 2 g of melamine and 7 g of ethylene glycol, stir and mix for 15 min, add concentrated hydrochloric acid to adjust the pH value of the solution to 4, stir and react for 4 h, centrifuge, wash, dry, and calcine at 550 ° C for 3 h to obtain a doped TiO2 / ZnO composite.

[0038] Test Example 1 Take 0.1g of the graphene-enhanced photocatalyst material prepared in Examples 1-3 or Comparative Examples 1-3, the doped TiO2 / ZnO composite prepared in Comparative Example 4 and 50mL of an aqueous solution of active red X-3B (concentration 0.05mol / L), and ultrasonically disperse for 10min. Shade the suspension and stir for 300min in the dark to establish adsorption-desorption equilibrium. Irradiate the suspension with a xenon lamp (300W). After 30min, take 3mL of the suspension sample and remove the photocatalyst solid particles by centrifugation. Use an ultraviolet-visible spectrophotometer to monitor the concentration of X3B in the filtrate, and evaluate the photocatalytic performance of the catalyst. X3B degradation rate calculation formula: (1) in is the initial concentration of X3B, is the concentration of X3B at degradation time t.

[0039] The results are shown in Table 1.

[0040] Table 1

[0041] It can be seen from the above table that the graphene enhanced photocatalyst materials prepared in Examples 1-3 of the present invention have a good effect of utilizing the light zone for photocatalytic degradation.

[0042] Test Example 2 The specific surface areas of the graphene-enhanced photocatalyst materials prepared in Examples 1-3 or Comparative Examples 1-3 and the doped TiO2 / ZnO composite prepared in Comparative Example 4 were measured using a 3-FLEX 3500 multi-station high-throughput gas adsorption instrument. The results are shown in Table 2.

[0043] Table 2

[0044] It can be seen from the above table that the graphene enhanced photocatalyst materials prepared in Examples 1-3 of the present invention have a larger specific surface area.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a graphene-enhanced photocatalyst material, characterized in that: The following steps are involved: S1. Dissolving silver nitrate and copper salt in an aqueous dispersion of graphene oxide to obtain an Ag / Cu-doped graphene oxide dispersion; S2. The tetrabutyl titanate and zinc acetate were dissolved in water, citric acid, melamine and ethylene glycol were added, the mixture was stirred and mixed, concentrated hydrochloric acid was added dropwise, the reaction was stirred, centrifuged, washed, dried and calcined to obtain a doped TiO2 / ZnO composite; S3. The doped TiO2 / ZnO composite was added to the Ag / Cu doped graphene oxide dispersion and spray dried to obtain a composite; S4. The composite is reduced with hydrazine hydrate vapor to obtain a graphene-enhanced photocatalyst material.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the silver nitrate, copper salt and graphene oxide aqueous dispersion in step S1 is 1-3:3-5:30-50.

3. The preparation method according to claim 1, characterized in that: The concentration of the graphene oxide aqueous dispersion in step S1 is 0.1-0.2 mg / mL, and the copper salt is selected from at least one of copper chloride, copper sulfate, and copper nitrate.

4. The preparation method according to claim 1, characterized in that: The mass ratio of tetrabutyl titanate, zinc acetate, citric acid, melamine and ethylene glycol in step S2 is 10-15:7-10:12-15:1-3:5-10.

5. The preparation method according to claim 1, characterized in that: In step S2, concentrated hydrochloric acid is added dropwise to adjust the pH value of the solution to 3-5.

6. The preparation method according to claim 1, characterized in that: The stirring reaction time in step S2 is 3-5h.

7. The preparation method according to claim 1, characterized in that: The calcination temperature in step S2 is 500-600° C. and the calcination time is 2-4 hours.

8. The preparation method according to claim 1, characterized in that: The solid-to-liquid ratio of the doped TiO2 / ZnO composite and the Ag / Cu doped graphene oxide dispersion in step S3 is 1:3-5 g / mL.

9. The preparation method according to claim 1, characterized in that: The time for reducing the hydrazine hydrate vapor in step S4 is 5-7 hours.

10. A graphene enhanced photocatalyst material prepared by the preparation method according to any one of claims 1 to 9.

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