A composite photocatalyst of b-doped g-c3n4 microrod loaded with w03 short fibers and a preparation method thereof

Abstract

The application discloses a composite photocatalyst of B-doped g-C3N4 microrod loaded with WO3 short fibers and a preparation method thereof. The method comprises the following steps: melamine, boron oxide, sodium tungstate dihydrate, urea and cetyltrimethylammonium bromide are proportioned according to the mass ratio of (1-10):(0.5-4):(1-6):(1-5):(0.2-3) to obtain a mixed powder, 60 mL of methanol is added, the mixture is fully dispersed, and then the mixed solution is quickly poured into a lining in a reaction kettle; the reaction kettle is sealed, placed in a vacuum drying box, and kept at 60-150 DEG C for 2-10 h, the reaction solution is poured out after cooling, centrifuged, washed and dried to obtain a precursor WB-CN; the WB-CN prepared in step two and ammonium fluoride are taken according to the mass ratio of (1-10):(0.5-3), ground, and then put into a white porcelain boat, covered, and placed in a muffle furnace for calcination, the heating speed is 4-10 DEG C / min, the temperature is 500-650 DEG C, and the holding time is 2-5 h; after calcination, the sample is dispersed in water, fully stirred, then centrifuged, washed and dried, so as to obtain a WO3 / B-g-C3N4 photocatalyst with stable structure and high hydrogen production efficiency, and the microstructure of the WO3 / B-g-C3N4 photocatalyst is that the WO3 short fibers are uniformly loaded on the g-C3N4 microrod.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional materials, and relates to a composite photocatalyst, in particular to a composite photocatalyst of B-doped g-C3N4 microrods loaded with WO3 short fibers and a preparation method thereof. BACKGROUND

[0002] Photocatalysis can convert solar energy into hydrogen energy, and can also remove environmental pollutants by using solar energy, and is considered as one of the core technologies of solar energy conversion and utilization that can "solve energy and environmental problems at the same time". Carriers with excellent light absorption and conversion performance are the key to realizing efficient conversion and utilization of solar energy, and finding photocatalysts with high catalytic activity, low cost and high content has become the basis for large-scale application of photocatalysis technology. Graphite carbon nitride (g-C3N4) has good visible light response ability (band gap of about 2.7 eV) and stable chemical properties, and by means of composition and process design, the photo-generated charge behavior can be controlled to build a high-performance g-C3N4-based light energy conversion system to realize efficient utilization of solar energy. In the study of g-C3N4 semiconductor visible light photocatalytic hydrogen production, a cocatalyst is needed to further improve the catalytic activity of the sample. So far, the common cocatalysts are some rare and expensive metals, which have high cost. Therefore, it is of great significance to develop a cocatalyst with high content and low cost to improve the photocatalytic activity of g-C3N4. SUMMARY

[0003] In view of the deficiencies in the prior art, the purpose of the present application is to provide a composite photocatalyst of B-doped g-C3N4 microrods loaded with WO3 short fibers and a preparation method thereof, which has simple and controllable preparation conditions and low production cost, and can prepare a composite photocatalyst of B-doped g-C3N4 microrods loaded with WO3 short fibers, which has stable structure and high hydrogen production efficiency.

[0004] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0005] A preparation method of a composite photocatalyst of B-doped g-C3N4 microrods loaded with WO3 short fibers, comprising the following steps:

[0006] Step one, melamine, boron oxide, sodium tungstate dihydrate, urea and cetyltrimethylammonium bromide are dosed according to a mass ratio of (1-10):(0.5-4):(1-6):(1-5):(0.2-3) to obtain a mixed powder, 60 mL of methanol is added, the mixed solution is dispersed sufficiently, and then the mixed solution is quickly poured into a 100 mL reactor liner;

[0007] Step two, seal the reactor, place in a vacuum drying oven for 2-10h, and take out the reactor after the temperature in the drying oven drops to room temperature, and cool the reaction solution, then pour out, centrifuge, wash and dry to obtain the precursor WB-CN;

[0008] Step three, grind the WB-CN prepared in step two and ammonium fluoride according to the mass ratio (1-10):(0.5-3), then put them into a white porcelain boat, cover the boat and place it in a muffle furnace, the heating rate is 4-10℃ / min, the temperature is 500-650℃, and the holding time is 2-5h;

[0009] Step four, after calcination, the sample is naturally cooled in the furnace and ground with a mortar, a gray powder can be obtained, which is dispersed in deionized water, fully stirred, then centrifuged, washed and dried to obtain the WO3 / B-g-C3N4 photocatalyst.

[0010] The application also has the following technical features:

[0011] Preferably, the sufficient dispersion in step one is ultrasonic for 45-125min, and then stirring on a magnetic stirrer for 120-720min.

[0012] Preferably, the washing in step two and step four is washing with deionized water and anhydrous ethanol for 3-5 times respectively.

[0013] Preferably, the drying in step two and step four is drying at 80℃ in a vacuum drying oven for 8-26h.

[0014] Preferably, the sufficient stirring in step four is stirring on a magnetic stirrer for 120-720min.

[0015] Preferably, the grinding in step four is grinding in a mortar for 30-90min.

[0016] The application also protects a composite photocatalyst of WO3 short fibers loaded on B-doped g-C3N4 microrods prepared by the above method, g-C3N4 has a unique rod structure, WO3 has a short fiber shape, and WO3 short fibers are uniformly loaded on g-C3N4 microrods.

[0017] Compared with the prior art, the application has the following technical effects:

[0018] In the process of preparing the WO3 / B-g-C3N4 composite photocatalytic material, the hydrothermal method and the solid phase sintering method are combined, the tungsten source, the boron source and carbon nitride are compounded, and then the composite photocatalytic material is obtained by one-step calcination, the preparation conditions are simple and easy to control, the production cost is low, and the industrial production is easy;

[0019] The preparation method adopted in the application makes the B-g-C3N4 form a uniform rod structure, the structure can be used to increase the specific surface area of the material, thereby enhancing the visible light absorption capacity of the material, effectively promoting the separation and transmission of photo-generated charges, and thereby achieving the goal of improving the hydrogen production efficiency;

[0020] The method for preparing WO3 / B-g-C3N4 proposed in the application forms WO3 short fiber uniformly attached B-g-C3N4 microrods, increases the contact area and adhesion of the material, and can promote the good transmission of photo-generated electrons between the materials, thereby effectively improving the hydrogen production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The X-ray diffraction analysis diagram of WO3 / B-g-C3N4 prepared for Example 1;

[0022] Figure 2 The scanning diagram of WO3 / B-g-C3N4 prepared for Example 1 under 10 mu m;

[0023] Figure 3 The hydrogen production performance test diagram of WO3 / B-g-C3N4 prepared for this example 1. DETAILED DESCRIPTION

[0024] The specific content of the application is further explained and described in detail in combination with the following examples.

[0025] Example 1:

[0026] Step one, the melamine, boron oxide (B2O3), sodium tungstate dihydrate, urea and CTAB (hexadecyl trimethyl ammonium bromide) are dosed according to the mass ratio of 5:2:1.4:3:2 to obtain a mixed powder A, 60 mL of methanol is added, ultrasonic is performed for 80 min first, then it is placed on a magnetic stirrer for stirring for 120 min, and then the mixed solution is quickly poured into the inner liner of a 100 mL reaction kettle;

[0027] Step two, the working temperature of the vacuum drying oven is set to 80 DEG C, after the temperature in the drying oven rises to the set temperature, the sealed reaction kettle is put into the oven, and the temperature is kept for 10 h, after the temperature in the oven decreases to room temperature, the reaction kettle is taken out and cooled, the cooled reaction solution is poured out and centrifuged, and then it is washed with deionized water and anhydrous ethanol for 3 times respectively to obtain a precipitate, which is then put into a vacuum drying oven for drying for 16 h to obtain a solid B, i.e. a precursor 1 (WB-CN);

[0028] Step three, the WB-CN and ammonium fluoride with a mass ratio of 8:1.5 are ground, then they are put into a white porcelain boat, covered with a cover and placed in a muffle furnace, the calcination temperature is 550 DEG C, the holding time is 4 h, and the temperature rising speed is 5 DEG C / min;

[0029] Step four, after calcination, the sample is naturally cooled in the furnace and ground in a mortar for 60 min to obtain a gray powder C. C is added to 100 mL of deionized water and stirred on a magnetic stirrer for 120 min. Then it is washed with deionized water and anhydrous ethanol for 3 times respectively to obtain a precipitate, which is then placed in a vacuum drying oven for 24 h to obtain a solid D, i.e. a WO3 / B-g-C3N4 photocatalyst;

[0030] The LabSolar 6A model device is used to test the photocatalytic effect of WO3 / B-g-C3N4. The specific test process includes weighing 55 mg of the composite photocatalyst and 10 mL of triethanolamine, and then placing them into a glass reaction vessel containing 90 mL of deionized water, and irradiating for 4 h.

[0031] Figure 1 The X-ray diffraction analysis chart of WO3 / B-g-C3N4 prepared in Example 1 is shown, in which the abscissa is the 2θ angle and the ordinate is the diffraction peak intensity. At 13° and 27°, it corresponds to the (100) crystal plane and (002) crystal plane of g-C3N4 respectively, and WO3 / B-g-C3N4 can also accurately correspond to WO3 PDF # 46-1096, indicating that the WO3 / B-g-C3N4 photocatalyst is successfully prepared.

[0032] Figure 2 The scanning chart of WO3 / B-g-C3N4 prepared in Example 1 at 10 μm is shown. From the figure, it can be clearly observed that WO3 is a nano short fiber structure, and B-g-C3N4 presents a rod-like structure and has WO3 nanofibers uniformly attached to its surface.

[0033] Figure 3 The hydrogen production performance test chart of WO3 / B-g-C3N4 prepared in this example 1 is shown. As shown in Figure 3 WO3 / B-g-C3N4 has good hydrogen evolution performance, and the total hydrogen production amount is 2908 μmol in 4 hours.

[0034] Example 2:

[0035] Step one, melamine, boron oxide (B2O3), sodium tungstate dihydrate, urea and CTAB (cetyltrimethylammonium bromide) are dosed according to a mass ratio of 8:4:4:3:2 to obtain a mixed powder A, and then 60 mL of methanol is added. First, ultrasonic for 100 min, then stir on a magnetic stirrer for 200 min, and then quickly pour the mixed solution into the inner liner of a 100 mL reaction kettle;

[0036] Step two, set the working temperature of the vacuum drying oven to 100℃, and when the temperature in the drying oven rises to the set temperature, put the sealed reaction kettle into the oven, and keep it for 6h. After the temperature in the oven drops to room temperature, take out the reaction kettle and cool it. Pour out the cooled reaction solution, centrifuge it, and wash it with deionized water and anhydrous ethanol for 4 times respectively to obtain the precipitate. Then put it into the vacuum drying oven to dry for 16h to obtain solid B, i.e. precursor 1 (WB-CN);

[0037] Step three, take WB-CN and ammonium fluoride with a mass ratio of 6:1, grind them, then put them into a white porcelain boat, cover the boat, and place it in a muffle furnace. The calcination temperature is 600℃, the holding time is 3h, and the heating rate is 6℃ / min;

[0038] Step four, after calcination, the sample is naturally cooled in the furnace and ground in a mortar for 60min to obtain gray powder C. Add C to 100mL of deionized water, place it on a magnetic stirrer and stir for 150min. Then wash it with deionized water and anhydrous ethanol for 4 times respectively to obtain the precipitate. Then put it into the vacuum drying oven to dry for 18h to obtain solid D, i.e. WO3 / B-g-C3N4 photocatalyst;

[0039] The LabSolar 6A type device is used to test the photocatalytic effect of WO3 / B-g-C3N4. The specific test process includes weighing 55mg of composite photocatalyst and 10mL of triethanolamine, and then putting them into a glass reaction vessel containing 90mL of deionized water. Light for 4h.

[0040] Example 3:

[0041] Step one, mix melamine, boron oxide (B2O3), sodium tungstate dihydrate, urea and CTAB (cetyltrimethylammonium bromide) according to a mass ratio of 10:3:4:3:1.2 to obtain mixed powder A. Then add 60mL of methanol, ultrasonic for 75min, and then place it on a magnetic stirrer and stir for 200min. Then quickly pour the mixed solution into the inner liner of a 100mL reaction kettle;

[0042] Step two, set the working temperature of the vacuum drying oven to 120℃, and when the temperature in the drying oven rises to the set temperature, put the sealed reaction kettle into the oven, and keep it for 5h. After the temperature in the oven drops to room temperature, take out the reaction kettle and cool it. Pour out the cooled reaction solution, centrifuge it, and wash it with deionized water and anhydrous ethanol for 5 times respectively to obtain the precipitate. Then put it into the vacuum drying oven to dry for 15h to obtain solid B, i.e. precursor 1 (WB-CN);

[0043] Step three, take the mass ratio of 9:2 WB-CN and ammonium fluoride after grinding and then put it into the white porcelain boat cover and place it in the muffle furnace, the calcination temperature is 650℃, the holding time is 3h, the heating rate is 10℃ / min;

[0044] Step four, after calcination, the sample is cooled naturally in the furnace and ground in a mortar for 60min, and a gray powder C can be obtained. Add C to 100mL of deionized water, place it on a magnetic stirrer and stir for 180min, then wash it with deionized water and anhydrous ethanol for 5 times respectively, get the precipitate, and then put it into a vacuum drying oven and dry for 16h, to obtain solid D, that is, WO3 / B-g-C3N4 photocatalyst is obtained;

[0045] LabSolar 6A type equipment is used to test the photocatalytic effect of WO3 / B-g-C3N4. The specific test process includes, take 55mg of composite photocatalyst and 10mL of triethanolamine, and put them into a glass reaction container containing 90mL of deionized water in turn, and irradiate for 4h.

[0046] Example 4:

[0047] Step one, mix melamine, boron oxide (B2O3), sodium tungstate dihydrate, urea and CTAB (hexadecyl trimethyl ammonium bromide) according to the mass ratio of 1:0.5:1:1:0.2 to obtain mixed powder A, then add 60mL of methanol, first ultrasonic for 45min, then place it on a magnetic stirrer and stir for 600min, then quickly pour the mixed solution into the inner liner of a 100mL reaction kettle;

[0048] Step two, set the working temperature of the vacuum drying oven to 60℃, and when the temperature in the drying oven rises to the set temperature, put the sealed reaction kettle into the oven and keep it for 8h. After the temperature in the oven drops to room temperature, take out the reaction kettle and cool it. Pour out the cooled reaction solution, centrifuge and wash it with deionized water and anhydrous ethanol for 5 times respectively to obtain the precipitate, and then put it into a vacuum drying oven and dry for 8h to obtain solid B, that is, precursor 1 (WB-CN);

[0049] Step three, take the mass ratio of 1:0.5 WB-CN and ammonium fluoride after grinding and then put it into the white porcelain boat cover and place it in the muffle furnace, the calcination temperature is 500℃, the holding time is 5h, the heating rate is 4℃ / min;

[0050] Step four, after calcination, the sample is cooled naturally in the furnace and ground in a mortar for 90min, and a gray powder C can be obtained. Add C to 100mL of deionized water, place it on a magnetic stirrer and stir for 480min, then wash it with deionized water and anhydrous ethanol for 5 times respectively, get the precipitate, and then put it into a vacuum drying oven and dry for 8h, to obtain solid D, that is, WO3 / B-g-C3N4 photocatalyst is obtained;

[0051] The LabSolar 6A model device was used to test the photocatalytic effect of WO3 / B-g-C3N4. The specific test process included weighing 55 mg of the composite photocatalyst and 10 mL of triethanolamine, and sequentially placing them into a glass reaction vessel containing 90 mL of deionized water, and irradiating for 4 h.

[0052] Example 5:

[0053] Step one, melamine, boron oxide (B2O3), sodium tungstate dihydrate, urea and CTAB (cetyltrimethylammonium bromide) were dosed according to a mass ratio of 6:4:6:5:3 to obtain a mixed powder A, 60 mL of methanol was then added, ultrasonic treatment was performed for 125 min, and then the mixture was stirred on a magnetic stirrer for 720 min, and then the mixed solution was quickly poured into the inner liner of a 100 mL reaction kettle;

[0054] Step two, the working temperature of the vacuum drying oven was set to 150°C, and after the temperature in the drying oven rose to the set temperature, the sealed reaction kettle was placed in the oven, and the temperature was kept for 2 h, and then the reaction kettle was taken out and cooled after the temperature in the oven dropped to room temperature, and the cooled reaction solution was poured out and centrifuged, and then washed with deionized water and anhydrous ethanol for 5 times respectively to obtain a precipitate, which was then placed in a vacuum drying oven for drying for 26 h to obtain solid B, i.e. precursor 1 (WB-CN);

[0055] Step three, WB-CN and ammonium fluoride with a mass ratio of 10:3 were ground and then placed in a white porcelain boat, covered with a lid and placed in a muffle furnace, the calcination temperature was 600°C, the holding time was 2 h, and the heating rate was 8°C / min;

[0056] Step four, after calcination, the sample was naturally cooled in the furnace and ground in a mortar for 30 min to obtain a gray powder C, which was then added to 100 mL of deionized water and stirred on a magnetic stirrer for 720 min, and then washed with deionized water and anhydrous ethanol for 5 times respectively to obtain a precipitate, which was then placed in a vacuum drying oven for drying for 26 h to obtain solid D, i.e. WO3 / B-g-C3N4 photocatalyst;

[0057] The LabSolar 6A model device was used to test the photocatalytic effect of WO3 / B-g-C3N4. The specific test process included weighing 55 mg of the composite photocatalyst and 10 mL of triethanolamine, and sequentially placing them into a glass reaction vessel containing 90 mL of deionized water, and irradiating for 4 h.

[0058] It should be pointed out finally that the above embodiments are only used for illustrating the technical solutions of the present application but not for limiting the same, and although the present application has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered in the scope of the present claims.

Claims

1. A method for preparing a composite photocatalyst consisting of WO3 short fibers supported on a B-doped g-C3N4 microrod, characterized in that, Includes the following steps: Step 1: Mix melamine, boron oxide, sodium tungstate dihydrate, urea and hexadecyltrimethylammonium bromide in a mass ratio of (1-10):(0.5-4):(1-6):(1-5):(0.2-3) to obtain a mixed powder. Then add 60 mL of methanol, disperse the mixture thoroughly, and quickly pour the mixture into the lining of a 100 mL reaction vessel. Step 2: Seal the reaction vessel and place it in a vacuum drying oven at 60-150℃ for 2-10 hours. After the temperature in the drying oven drops to room temperature, remove the reaction vessel and cool it. Pour out the cooled reaction solution, centrifuge, wash, and dry to obtain the precursor WB-CN. Step 3: Take the WB-CN and ammonium fluoride prepared in Step 2 at a mass ratio of (1-10):(0.5-3), grind them, put them into a white porcelain boat, cover it, and place it in a muffle furnace for calcination. The heating rate is 4-10℃ / min, the temperature is 500-650℃, and the holding time is 2-5h. Step 4: After calcination, the sample is naturally cooled in the furnace and ground in a mortar to obtain a gray powder. The powder is dispersed in deionized water, stirred thoroughly, and then centrifuged, washed, and dried to obtain the WO3 / Bg-C3N4 photocatalyst.

2. The method for preparing the composite photocatalyst with WO3 short fibers supported on a B-doped g-C3N4 microrod as described in claim 1, characterized in that, The thorough dispersion in step one involves sonicating the mixture for 45–125 minutes, and then stirring it on a magnetic stirrer for 120–720 minutes.

3. The method for preparing the composite photocatalyst with WO3 short fibers supported on a B-doped g-C3N4 microrod as described in claim 1, characterized in that, The washing described in steps two and four involves washing with deionized water and anhydrous ethanol 3 to 5 times respectively.

4. The method for preparing the composite photocatalyst with WO3 short fibers supported on a B-doped g-C3N4 microrod as described in claim 1, characterized in that, The drying process described in steps two and four involves drying at 80°C in a vacuum drying oven for 8–26 hours.

5. The method for preparing the composite photocatalyst with WO3 short fibers supported on a B-doped g-C3N4 microrod as described in claim 1, characterized in that, The thorough stirring described in step four involves stirring on a magnetic stirrer for 120–720 minutes.

6. The method for preparing the composite photocatalyst with WO3 short fibers supported on a B-doped g-C3N4 microrod as described in claim 1, characterized in that, The grinding described in step four involves grinding in a mortar for 30 to 90 minutes.

7. A composite photocatalyst prepared by the method described in any one of claims 1 to 6, comprising B-doped g-C3N4 microrods loaded with WO3 short fibers, characterized in that, g-C3N4 exhibits a unique rod-like structure, while WO3 presents as short fibers. The WO3 short fibers are uniformly loaded onto the g-C3N4 micron rods.

Images