CN106111107A - A kind of Zinc oxide nano sheet catalyst of titania additive - Google Patents

Abstract

The Zinc oxide nano sheet catalyst of a kind of titania additive of the present invention uses hydro-thermal reaction method, first prepare ZnO nano sheet, again ZnO nano sheet and isopropyl titanate are reacted with diethylenetriamine, obtain the Zinc oxide nano sheet catalyst of titania additive, wherein Zn(NO₃)₂·6H₂O controls at 1:0.5 ~ 1:1 with the mol ratio of hexamethylenetetramine, and ZnO nano sheet is 10:1 ~ 1:1 with the mol ratio of metatitanic acid second butyl ester, and isopropyl titanate is 6:1 with the volume ratio of diethylenetriamine.The Zinc oxide nano sheet catalyst of titania additive of the present invention has good photocatalysis effect, organic matter degradation can be made complete in 2 h.

Description

A titanium dioxide-doped zinc oxide nanosheet catalyst

technical field

The invention relates to a zinc oxide nanosheet catalyst doped with titanium dioxide, and specifically belongs to the technical field of photocatalyst materials.

Background technique

As a green catalyst, great progress has been made in recent years. The great impetus to promote the research of photocatalytic reaction comes from the strong requirements of clean production, energy crisis and environmental protection, as well as the potential exploration value and application potential of photocatalyst itself. Zinc oxide photocatalyst can play a big role in environmental protection. Its strong catalytic degradation ability can turn most pollutants into harmless substances, contribute to the protection of water resources, and can solve the problem of sewage discharge by the country and enterprises. The poisonous substance CN ^- is degraded into nontoxic substances CO ₂ , N ₂ , NO ³ - by using ZnO. Because the photocatalytic reaction meets low energy consumption and is environmentally friendly, it has been favored by many scholars. In recent years, scientists have made in-depth research on photocatalytic reactions and have achieved gratifying results. Therefore, photocatalytic reactions have become an important method of catalytic reactions.

Surface photosensitization is to adsorb a photoactive sensitizer on the surface of ZnO. Under the light, the sensitized molecule absorbs photons to generate free electrons, which transfer to the surface of ZnO, and at the same time, the holes generated after ZnO is excited are transferred to the valence band of the photosensitizer. , so that its absorption spectrum shifts to the direction of visible light, thereby expanding the range of ZnO absorption wavelengths and improving the photocatalytic efficiency of visible light. Semiconductor recombination uses the difference in conduction band and valence band between two semiconductor components to fully separate photogenerated carriers and expand the spectral response range of the recombination system to achieve the purpose of improving photocatalytic efficiency. Titanium dioxide photocatalyst has been widely used in various fields due to its advantages of safety, non-toxicity, stable chemical properties, high energy efficiency, and no pollution. As a wide bandgap semiconductor material, it also has a good application prospect in the field of environmental pollution control. Most of the anatase TiO ₂ are [101] plane TiO ₂ with good thermal stability (the content is greater than 94%). However, the [001] plane has higher activity than the [101] plane, but the average surface energy of the [001] plane anatase TiO ₂ is 0.90 J/m ² , much larger than the [101] plane (0.44 J/m ² ), which are extremely difficult to form during the synthesis process.

Through the research on ZnO/TiO ₂ photocatalyst, the present application found that the highly exposed [001] plane TiO ₂ itself has higher catalytic efficiency and activity. advantage. In addition, the influence of nanoparticle size is relatively large, and the activity changes with the particle size. When the heterojunction is irradiated by photons with energy greater than its forbidden band, photogenerated holes and photogenerated electrons are generated on its surface, and the photogenerated electrons react with oxygen to generate superoxide ion O ^2- , which can decompose many refractory organic compounds It is decomposed into inorganic substances such as CO ₂ and H ₂ O. Based on these excellent properties, the present application finds a preparation method to combine zinc oxide and titanium dioxide to produce a photocatalyst with excellent performance.

The present invention adopts hydrothermal method to prepare ZnO/TiO ₂ photocatalyst, and allows TiO ₂ with [001] plane to grow on ZnO, so that the size of the two substances in the formed heterojunction reaches a just suitable size. The catalytic degradation of organic dyes shows that the performance of the catalyst of the present invention is excellent. The difference between the heterojunction of the catalyst of the present invention and other methods is that on ZnO nanometers, _TiO2 is grown on ZnO with a [001] plane, so that the size of the two substances in the formed heterojunction reaches one Just the right size, and the [001] plane of _TiO2 in the heterojunction still has a high proportion, and the surface of the heterojunction is smooth and smooth, and the organic dye has a unique degradation effect, which can completely degrade the organic matter within 2 hours .

Contents of the invention

Titanium dioxide-doped zinc oxide nanosheet catalyst, the preparation of the catalyst comprises the following steps:

Step 1: Preparation of ZnO nanosheets

Dissolve Zn(NO ₃ ) ₂ ·6H ₂ O and hexamethylenetetramine in deionized water with a magnet, react in an oil bath at 90°C for 8 hours, and then cool to room temperature. The cake was vacuum-dried at 60° C. for 24 hours to obtain ZnO nanosheets; the molar ratio of Zn(NO ₃ ) ₂ ·6H ₂ O to hexamethylenetetramine was controlled at 1:0.5˜1:1.

Step 2: Preparation of TiO-doped ZnO nanosheet catalyst

Add the ZnO nanosheets prepared in step 1 into isopropanol, after ultrasonic dissolution is complete, then add isopropyl titanate and diethylenetriamine dropwise, continue ultrasonic treatment for 40min, and then heat at 200°C Reacted for 24 hours; after the reaction product was cooled, it was centrifuged, and the obtained precipitate was washed three times with deionized water and ethanol respectively, and after being centrifuged at a speed of 8000r/min, it was vacuum-dried at 60°C for 24 hours; The vacuum-dried product was calcined at 400°C for 2 hours, and then annealed to obtain a titanium dioxide-doped zinc oxide nanosheet catalyst; The molar ratio is 10:1-1:1, and the volume ratio of isopropyl titanate to diethylenetriamine is 6:1.

In the catalyst, titanium dioxide accounts for 20%-80% of the mass percentage of the titanium dioxide-doped zinc oxide nanosheet catalyst.

Beneficial effects of the present invention:

ZnO and TiO ₂ have a similar band gap (Eg=3.37eV). Compared with TiO ₂ , ZnO has a direct band gap and high electron mobility. ZnO has a relatively _TiO2 has better photocatalytic effect. The preparation of the heterojunction of the titanium dioxide-doped zinc oxide nanosheet catalyst of the present invention is different from other methods on the ZnO nanometer, allowing _TiO2 to grow on the ZnO with the [001] plane, so that the heterojunction formed The size of the two substances in the heterojunction reaches a just suitable size, and the [001] plane of TiO ₂ in the heterojunction still has a high proportion, and the surface morphology of the heterojunction is flat and smooth, and the organic dye has a unique degradation effect , The organic matter can be completely degraded within 2 hours.

detailed description

Example 1

Weigh 5.3548g of Zn(NO ₃ ) ₂ ·6H ₂ O and 2.5234g of hexamethylenetetramine. Dissolve the claimed medicine in a 100mL beaker with 60mL deionized water inside. Add a magnet and put it in a 90°C oil bath for 8 hours. Cool to room temperature, filter and dry in a vacuum oven at 60°C for 24 hours.

Example 2

Take a beaker and add 55mL isopropanol to the beaker, then add 0.5g ZnO, place the beaker in an ultrasonic machine, ultrasonically dissolve, after the dissolution is complete, add 0.18mL isopropyl titanate (TIP) and 0.03mL Diethylenetriamine (DETA) continued to be sonicated for 40min, transferred to a 50mL autoclave, and then placed in an oven at 200°C for 24h. After the reaction is cooled, pour it into a centrifuge large test tube to mark it, and centrifuge it, wash it three times with deionized water and ethanol, and centrifuge at 8000r/min. The obtained product was put into a vacuum drying oven for vacuum drying at 60° C. for 24 hours. Finally, the product is put into the muffle furnace at 400°C/2h, and the rate is about 1°C/min for annealing and quenching treatment. A ZnO/TiO ₂ catalyst with a TiO ₂ doping content of 20% was prepared.

Example 3

Take a beaker and add 55mL isopropanol to the beaker, then add 0.5g ZnO, place the beaker in an ultrasonic machine, ultrasonically dissolve, after the dissolution is complete, add 0.36mL isopropyl titanate (TIP) and 0.06mL Diethylenetriamine (DETA) continued to be sonicated for 40min, transferred to a 50mL autoclave, and then placed in an oven at 200°C for 24h. After the reaction is cooled, pour it into a centrifuge large test tube to mark it, and centrifuge it, wash it three times with deionized water and ethanol, and centrifuge at 8000r/min. The obtained product was put into a vacuum drying oven for vacuum drying at 60° C. for 24 hours. Finally, the product is put into the muffle furnace at 400°C/2h, and the rate is about 1°C/min for annealing and quenching treatment. A ZnO/TiO ₂ catalyst with a TiO ₂ doping content of 40% was prepared.

Example 4

Take a beaker and add 55mL isopropanol to the beaker, then add 0.5g ZnO, place the beaker in an ultrasonic machine, ultrasonically dissolve, after the dissolution is complete, add 0.72mL isopropyl titanate (TIP) and 0.12mL Diethylenetriamine (DETA) continued to be sonicated for 40min, transferred to a 50mL autoclave, and then placed in an oven at 200°C for 24h. After the reaction is cooled, pour it into a centrifuge large test tube to mark it, and centrifuge it, wash it three times with deionized water and ethanol, and centrifuge at 8000r/min. The obtained product was put into a vacuum drying oven for vacuum drying at 60° C. for 24 hours. Finally, the product is put into the muffle furnace at 400°C/2h, and the rate is about 1°C/min for annealing and quenching treatment. The ZnO/TiO ₂ catalyst with a TiO ₂ doping content of 60% was prepared.

Example 5

Take a beaker and add 55mL isopropanol to the beaker, then add 0.5g ZnO, place the beaker in an ultrasonic machine, ultrasonically dissolve, after the dissolution is complete, add 1.44mL isopropyl titanate (TIP) and 0.24mL Diethylenetriamine (DETA) continued to be sonicated for 40min, transferred to a 50mL autoclave, and then placed in an oven at 200°C for 24h. After the reaction is cooled, pour it into a centrifuge large test tube to mark it, and centrifuge it, wash it three times with deionized water and ethanol, and centrifuge at 8000r/min. The obtained product was put into a vacuum drying oven for vacuum drying at 60° C. for 24 hours. Finally, the product is put into the muffle furnace at 400°C/2h, and the rate is about 1°C/min for annealing and quenching treatment. A ZnO/TiO ₂ catalyst with a TiO ₂ doping content of 80% was prepared.

Claims (2)

1. a zinc oxide nanosheet catalyst doped with titanium dioxide, is characterized in that: the preparation of described catalyst comprises the steps: Step 1: Preparation of ZnO nanosheets Dissolve Zn(NO ₃ ) ₂ ·6H ₂ O and hexamethylenetetramine in deionized water with a magnet, react in an oil bath at 90°C for 8 h, then cool to room temperature, and filter the reaction product to obtain The filter cake was vacuum-dried at 60°C for 24 h to obtain ZnO nanosheets; the molar ratio of Zn(NO ₃ ) ₂ 6H ₂ O to hexamethylenetetramine was controlled at 1:1~2:1; Step 2: Preparation of TiO-doped ZnO nanosheet catalyst Add the ZnO nanosheets prepared in step 1 into isopropanol, and after ultrasonic dissolution is complete, then add isopropyl titanate and diethylenetriamine dropwise, and continue the ultrasonic treatment for 40 min, and then place them under the condition of 200 °C Heating and reacting for 24 h; after the reaction product was cooled, it was centrifuged, and the obtained precipitate was washed three times with deionized water and ethanol respectively, and after being centrifuged at a speed of 8000 r/min, it was vacuum-dried at 60 °C for 24 h ; Thereafter, the vacuum-dried product was calcined at 400°C for 2h, and then annealed to obtain a titanium dioxide-doped zinc oxide nanosheet catalyst; The molar ratio of ethyl butyl ester is 10:1~1:1, and the volume ratio of isopropyl titanate to diethylenetriamine is 6:1. 2. a kind of zinc oxide nanosheet catalyst doped with titanium dioxide according to claim 1, is characterized in that: in described catalyzer, titanium dioxide accounts for 20%～80% of the zinc oxide nanosheet catalyst mass percent of titanium dioxide doping .