CN105817253A - Method for preparing graphite phase carbon nitride nanosheet/titania nanotube array photocatalysis material - Google Patents

Abstract

The invention discloses a preparation method of a graphite-phase carbon nitride nanosheet/titanium dioxide nanotube array photocatalyst material, comprising: 1. thermally polycondensing melamine to prepare graphite-phase carbon nitride powder; 2. ultrasonic exfoliation of bulk-phase graphite-phase carbon nitride Obtain graphite phase carbon nitride nanosheets; 3. Add carbon nitride nanosheets to the electrolyte to synthesize graphite phase carbon nitride nanosheets/amorphous titanium dioxide nanotube arrays in one step during the anodic oxidation process; 4. Anodic oxidation The obtained samples were heat-treated to prepare graphitic carbon nitride nanosheet/titanium dioxide nanotube array materials. The method of the present invention makes graphite phase carbon nitride nanosheet/titanium dioxide nanotube array photocatalytic material quickly and economically in one step, and the obtained photocatalyst overcomes the shortcomings of titanium dioxide nanotube array and bulk phase graphite phase carbon nitride, and improves It improves the utilization rate of visible light, reduces the recombination rate of photogenerated electrons and holes, and can efficiently photocatalyze the degradation of organic pollutants under visible light irradiation.

Description

Preparation method of graphitic phase carbon nitride nanosheet/titanium dioxide nanotube array photocatalytic material

technical field

The invention relates to a preparation method of a graphite-phase carbon nitride nanosheet/titanium dioxide nanotube array photocatalyst material, which belongs to the technical field of photocatalytic environment-friendly nanomaterials.

Background technique

Carbon nitride material has five allotropes, among which graphite phase carbon nitride material is the most stable one. Since Antonietti et al. reported in 2009 that graphitic carbon nitride can be used in the field of photocatalysis (Nat.Mater., 2009, 8, 76-80.), this kind of non-metallic material with good stability, environmental protection, non-toxicity and cheap raw materials It has received extensive attention in the field of photocatalysis. The forbidden band width of graphitic carbon nitride is 2.7eV, which allows it to effectively absorb visible light and have a high utilization efficiency for sunlight. However, the photocatalytic efficiency of the bulk graphitic carbon nitride prepared by calcining the graphitic carbon nitride precursor by high-temperature polycondensation method still needs to be improved due to the disadvantages of large specific surface area and fast recombination of photogenerated electrons and holes. In order to solve these problems, the doping of bulk graphitic carbon nitride, the introduction of nitrogen vacancies, coupling with other semiconductor materials, and morphology control are regulated to effectively improve its photocatalytic efficiency.

Due to their unique structure, nanosheets often have high photocatalytic efficiency compared with traditional nanoparticles. Graphite carbon nitride has a layered structure similar to graphite, and nanosheet-like graphitic carbon nitride can be obtained by exfoliation to improve its photocatalytic performance. There have been many reports on the successful preparation of graphitic carbon nitride nanosheets by different exfoliation methods, such as liquid phase exfoliation (Advanced materials, 2013, 25, 2452-2456; Journal of Materials Chemistry A, 2014, 2, 2563-2570.), ultrasonic exfoliation (AppliedCatalysisB: Environmental, 2014, 152-153, 46-50.), thermal oxidation corrosion stripping (Advanced Functional Materials, 2012, 22, 4763-4770.), chemical stripping (Journal ofMaterialsChemistryA, 2013, 1, 14766-14772), etc. These exfoliated graphitic carbon nitride nanosheets have a larger specific surface area, which can provide more reactive sites and reduce the recombination efficiency of photogenerated carriers, which can improve the efficiency of photocatalytic reactions to a certain extent. However, due to the single component and structure, its photogenerated charge separation ability and photocatalytic efficiency still need to be improved.

As a traditional n-type semiconductor photocatalyst, titanium dioxide has the advantages of economy, non-toxicity, good stability, and environmental friendliness. It has been widely studied and applied in the field of photocatalysis, and is currently the most studied photocatalyst material. However, its bandgap of 3.2 eV makes it inefficient to use sunlight. Combining narrow-bandgap graphitic carbon nitride with wide-bandgap titanium dioxide can optimize its visible light absorption and enhance the separation of photogenerated phones, resulting in a photocatalytic material with good visible light catalytic performance. Current research has only focused on composites of graphitic carbon nitride particles with nanoscale titania particles. Compared with traditional titanium dioxide materials, titanium dioxide nanotube arrays arranged in an orderly manner have the advantages of larger specific surface area, better electron transport capacity, and good recycling performance. In fact, the advantages of both can be effectively utilized to overcome the shortcomings of titanium dioxide, such as poor response to visible light and fast recombination rate of photogenerated electrons and holes, and can prepare new materials for high-efficiency visible light catalysts that are easy to recycle.

Contents of the invention

Aiming at the problem of low visible light catalytic efficiency of a single carbon nitride nanosheet, the invention provides a simple method for preparing a graphite-phase carbon nitride nanosheet/titanium dioxide nanotube array photocatalytic material. The method can quickly fix the graphitic carbon nitride nanosheets on the titanium dioxide nanotube array. The preparation method is simple, fast and easy to operate. Photocatalytic degradation has obvious effect.

Technical scheme of the present invention is as follows:

1) Put 10g of melamine into a crucible with a lid, place it in a muffle furnace, heat up to 450-550°C for 2-4 hours at a heating rate of 10°C/min. After calcination, it was naturally cooled to room temperature, and the obtained sample was ground into powder to obtain bulk graphite phase carbon nitride.

2) Add 2 g of the bulk graphite phase carbon nitride prepared in step 1 into 30-60 ml of concentrated sulfuric acid and keep stirring for 8 h. Then slowly pour the mixture into 200ml of deionized water, ultrasonically strip it for 6-10 hours, then centrifuge at 1000rmp and wash the precipitate with deionized water repeatedly for 5-15 times to obtain colloidal graphite phase carbon nitride nanosheets, and then The sheet colloidal solution was further ultrasonically pulverized for 0-60 minutes to obtain graphite phase carbon nitride nanosheets with smaller sizes;

3) pickling the titanium sheet with a purity >99%, and ultrasonically cleaning it in organic solution and water for 15 minutes respectively to obtain the base material for preparing titanium dioxide nanotube array by anodic oxidation;

4) Take 30-70ml of the graphite phase carbon nitride nanosheets prepared in step 2 with a concentration of 0.05-0.2g/L, add the graphite phase carbon nitride nanosheet aqueous solution into the prepared anodic oxidation electrolyte and stir evenly , anodize at 20V for 2h, and keep stirring during the anodizing process, the stirring speed is 100rpm-500rpm.

5) After the anodic oxidation, the amorphous titanium dioxide nanotube array sample was taken out for heat treatment, and the temperature was raised from room temperature to 400°C-500°C for 1-3 hours at a heating rate of 2°C/min.

Wherein, the pickling solution in step 3 is water: nitric acid: hydrofluoric acid=5: 4: 1 (V/V/V) mixed solution; ultrasonic cleaning organic solution is acetone, isopropanol, methanol, ethanol;

In step 4, the electrolyte is water: glycerol=1:1 (v/v), 0.27M ammonium fluoride mixed solution;

Compared with the prior art, the beneficial effects of the present invention are: the preparation method of the present invention is simple, economical and convenient, the prepared photocatalyst has excellent visible light catalytic performance, can efficiently degrade rhodamine B under visible light irradiation, and is pure titanium dioxide 4 times that of nanotubes.

Description of drawings

Fig. 1 is the graphitic phase carbon nitride nanosheet transmission electron micrograph that embodiment one step 2 prepares;

Fig. 2 is the scanning electron micrograph of the graphite phase carbon nitride nanosheet/titanium dioxide nanotube array prepared in embodiment one;

Fig. 3 is the transmission electron microscope picture of the graphite phase carbon nitride nanosheet/titanium dioxide nanotube array prepared in embodiment one;

Fig. 4 is the XRD pattern of the graphitic phase carbon nitride nanosheet/titanium dioxide nanotube array prepared in embodiment one;

Figure 5 is a photocatalytic degradation performance diagram of rhodamine B dye degradation under visible light irradiation of the graphitic phase carbon nitride nanosheet/titanium dioxide nanotube array prepared in Example 1;

detailed description

The following are specific embodiments of the present invention to further illustrate the present invention, but the present invention is not limited thereto.

Specific implementation mode 1: This implementation mode is a simple preparation of graphite-phase carbon nitride nanosheet/titanium dioxide nanotube array photocatalytic material, and the specific steps are as follows:

1) Put 10g of melamine into a crucible with a lid, place it in a muffle furnace and calcinate at a temperature of 450-550°C for 2-4 hours, with a heating rate of 10°C/min. After the calcination, it was naturally cooled to room temperature, and the obtained sample was ground into powder to prepare bulk graphite phase carbon nitride;

2) Take 2g of the bulk graphitic carbon nitride prepared in step 1 and add it into 30-50ml of concentrated sulfuric acid and keep stirring for 8h. Then slowly pour the mixture into 200ml of deionized water, ultrasonically strip it for 6-10 hours, then centrifuge at 1000rmp and wash the precipitate with deionized water repeatedly for 5-15 times to obtain colloidal graphite phase carbon nitride nanosheets, and then The sheet colloidal solution was further ultrasonically pulverized for 0-60 minutes to obtain graphite phase carbon nitride nanosheets with smaller sizes;

3) pickling the titanium sheet with a purity >99%, and ultrasonically cleaning it in acetone, isopropanol, methanol, ethanol and water for 15 minutes respectively to obtain the base material for anodic oxidation to prepare titanium dioxide nanotube arrays;

4) Take 30-70ml of the graphite phase carbon nitride nanosheets prepared in step 2 with a concentration of 0.1g/L, and add the graphite phase carbon nitride nanosheets aqueous solution to water: glycerol = 1: 1 (v/ v), stir evenly in 0.27M ammonium fluoride mixed anodizing electrolyte, anodize at 20V for 2h, and keep stirring during the anodizing process, the stirring speed is 100-500 rpm.

5) After the anodic oxidation, the amorphous titanium dioxide nanotube array sample was taken out for heat treatment, and the temperature was raised from room temperature to 400°C-500°C for 1-3 hours at a heating rate of 2°C/min.

Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the calcination temperature in step 1 is 520°C. Others are the same as the first embodiment.

Specific embodiment 3: The difference between this embodiment and specific embodiment 1 is that the number of times of washing with deionized water in step 2 is 10 times. Others are the same as the first embodiment.

Specific embodiment 4: The difference between this embodiment and specific embodiment 1 is that the ultrasonic pulverization time in step 2 is 20-60 min. Others are the same as the first embodiment.

Specific embodiment five: the difference between this embodiment and specific embodiments one to four is that the ultrasonic pulverization time in step two is 60 minutes. Others are the same as the first embodiment.

Specific embodiment six: the difference between this embodiment and specific embodiment one is that the stirring speed in step four is 200 rpm. Others are the same as the first embodiment.

The present invention uses the following examples to verify that the graphitic carbon nitride nanosheet/titanium dioxide nanotube array photocatalyst has improved visible light efficiency:

Embodiment one:

a) Put 10 g of melamine into a crucible with a lid, and place it in a muffle furnace for calcination at a temperature of 520° C. for 2 hours, with a heating rate of 10° C./min. After the calcination, it was naturally cooled to room temperature, and the obtained sample was ground into powder to prepare bulk graphite phase carbon nitride;

b) Add 2 g of the bulk graphitic carbon nitride prepared in step 1 into 40 ml of concentrated sulfuric acid and keep stirring for 8 h. Then the mixture is slowly poured into 200ml of deionized water, ultrasonically stripped for 8h, and then centrifuged at 1000rmp, the precipitate is repeatedly washed with deionized water for 10 times to obtain colloidal graphite phase carbon nitride nanosheets, and then the nanosheet colloidal solution is further Ultrasonic pulverization for 60 minutes to obtain graphite phase carbon nitride nanosheets with smaller size;

c) acid-washing the titanium sheet with a purity >99%, and then ultrasonically cleaning it in acetone, isopropanol, methanol, ethanol and water for 15 minutes respectively to obtain a base material for preparing titanium dioxide nanotube arrays by anodic oxidation;

d) Take 50ml of the graphite phase carbon nitride nanosheets with a concentration of 0.1g/L prepared in step 2, and add the graphite phase carbon nitride nanosheets aqueous solution to water: glycerol=1:1 (v/v) , Stir evenly in 0.27M ammonium fluoride mixed anodizing electrolyte, anodize at 20V for 2h, and keep stirring during the anodizing process, the stirring speed is 200 rpm.

e) After the anodic oxidation, the amorphous titanium dioxide nanotube array sample was taken out for heat treatment, and the temperature was raised from room temperature to 450° C. for 3 hours at a heating rate of 2° C./min.

The transmission electron microscope image of the graphite phase carbon nitride nanosheets obtained in step 2 of this embodiment is shown in Figure 1, and it can be seen from the figure that the graphite phase carbon nitride nanosheets obtained are in the shape of nanosheets;

The top view of the scanning electron microscope of the graphitic carbon nitride nanosheet/titanium dioxide nanotube array prepared by this embodiment is shown in Figure 2, and it can be observed from the figure that the regularly arranged titanium dioxide nanotube array with a diameter of about 50-100nm is observed. And the nozzle is not covered by a large number of graphitic carbon nitride nanosheets, which is conducive to the absorption of light by the titanium dioxide nanotube array;

The transmission electron micrograph of the graphite phase carbon nitride nanosheet/titanium dioxide nanotube array prepared by this embodiment is shown in Figure 3, and it is observed from Figure 3 that there is a small amount of graphite phase nitride on the tube wall of the titanium dioxide nanotube Carbon nanosheets are tightly loaded;

The XRD pattern of the graphitic phase carbon nitride nanosheet/titanium dioxide nanotube array prepared by this embodiment is shown in Figure 4. From the XRD pattern, it can be observed that what Example 1 obtains through heat treatment is anatase phase titanium dioxide, and in There is a faint peak at 27.4° corresponding to the diffraction peak of the graphitic carbon nitride nanosheet (002) crystal plane;

In order to verify the visible light catalytic activity of the graphitic carbon nitride nanosheet/titanium dioxide nanotube array photocatalytic material obtained in Example 1, the specific steps are as follows:

Take the graphitic phase carbon nitride nanosheet/titanium dioxide nanotube array obtained in Example 1 with a size of 2cm×2cm and place it in a 30mL beaker, then add 20mL of rhodamine B solution with a concentration of 5mg/L, and stir under constant magnetic force Place it under a 300W xenon lamp for irradiation. The xenon lamp is covered with a 420nm filter to filter out ultraviolet light. Quickly take out 4mL rhodamine B solution every 30 minutes and measure the absorbance change of rhodamine B with a UV spectrophotometer. continue to react

Visible light-catalyzed degradation of rhodamine B solution by the graphitic phase carbon nitride nanosheet/titanium dioxide nanotube array prepared in this example. Titanium dioxide nanotube arrays have good visible light catalytic performance, and the degradation of rhodamine B solution within 300 minutes has reached 88%, which is 4 times higher than that of unloaded titanium dioxide nanotube arrays, and has higher visible light catalytic ability. .

Claims (6)

1. A preparation method of graphitic phase carbon nitride nanosheet/titanium dioxide nanotube array photocatalytic material, is characterized in that, comprises the following steps: 1) Put 10 g of melamine into a crucible with a lid, and place it in a muffle furnace for calcination at a certain temperature with a heating rate of 10° C./min. After the calcination, it was naturally cooled to room temperature, and the obtained sample was ground into powder to prepare bulk graphite phase carbon nitride; 2) Add 2 g of the bulk graphite phase carbon nitride prepared in step 1 into 30-60 ml of concentrated sulfuric acid and keep stirring for 8 h. Then slowly pour the mixture into 200ml of deionized water, ultrasonically strip it for 6-10 hours, and then centrifuge at 1000rmp, rinse the precipitate several times with deionized water to obtain colloidal graphite phase carbon nitride nanosheets, and then colloidal nanosheets The solution is further ultrasonically pulverized for a certain period of time to obtain graphite-phase carbon nitride nanosheets with smaller sizes; 3) pickling the titanium sheet with a purity >99%, and then ultrasonically cleaning it in organic solution and water for 15 minutes respectively to obtain the base material for preparing titanium dioxide nanotube array by anodic oxidation; 4) Take 30-70ml of a certain concentration of graphite phase carbon nitride nanosheets prepared in step 2, add the aqueous solution of graphite phase carbon nitride nanosheets into the prepared anodic oxidation electrolyte and stir evenly, anodize at 20V for 2h , and keep stirring at a certain speed during the anodizing process; 5) After the anodic oxidation is finished, the amorphous titania nanotube array sample is taken out for heat treatment, and the temperature is raised from room temperature to a certain temperature at a heating rate of 2° C./min for 1 to 3 hours. 2. The preparation method according to claim 1, characterized in that in step 1, the calcination temperature is 450-550°C, and the calcination time is 2-4 hours. 3. The preparation method according to claim 1, characterized in that in step 2, the number of times of rinsing with deionized water is 5-15 times. 4. The preparation method according to claim 1, characterized in that in step 2, the ultrasonic pulverization time is 10-70 min. 5. The preparation method according to claim 1, characterized in that in step 4, the concentration of the graphite phase carbon nitride nanosheets is 0.05-0.2g/L. 6. The preparation method according to claim 1, characterized in that in step 4, the stirring speed is 100-500 rpm.