Method for synthesizing anatase/brookite nano composite material for photocatalytic decomposition of water into hydrogen through one-step hydrothermal method

A one-step hydrothermal method for synthesizing anatase/brookite nanocomposite material used for photolysis of water to produce hydrogenTechnical field

[0001] The present invention relates to a method for synthesizing a Ti() 2 mixed crystal phase (anatase/brookite) nanocomposite by a one-step hydrothermal method.

Background technique

[0002] At present, in the face of the increasing global demand for energy and the serious environmental crisis, the search for new energy sources to replace fossil energy has attracted more and more attention. Hydrogen energy is a good green energy. As a secondary energy source, it has many advantages such as clean, high efficiency, safety, storage, and transportability, so it is highly valued by all countries. However, the current hydrogen production method is mainly industrial hydrogen production, which usually adopts unenvironmental and economical methods such as natural gas steam reforming process. Photolysis of water technology is the first report of two professors, Fujishama and Honda of the University of Tokyo, Japan. They discovered the phenomenon that TiO2 single crystal electrode photocatalytically decomposes water to produce hydrogen, which reveals the possibility of using solar energy to directly decompose water to produce hydrogen, and opens up the use of solar energy. The research on photolysis of water to produce hydrogen has made great progress in the synthesis and modification of photocatalysts, and some photocatalysts responsive to visible light have been successively obtained. Tit)? As an important semiconductor, it has been extensively studied, and studies have shown that it can be used as a catalyst for photolysis of water to produce hydrogen. However, due to the large band gap of Tit) 2 (3.2ev), the recombination rate of photogenerated carriers is high, the surface active sites are few, and agglomeration is prone to occur, resulting in low solar utilization and poor photocatalytic activity. This largely limits its application in photocatalysis.

Summary of the invention

[0003] The purpose of the present invention is to synthesize the structure of Tit) itself mixed crystal phase, to solve the existing preparation of titanium dioxide photocatalytic material photo-generated carrier recombination probability is high, surface active sites are few, prone to agglomeration caused by photocatalysis The problem of poor activity is to provide a one-step hydrothermal method to synthesize anatase/brookite nanocomposite materials for photolysis of water to produce hydrogen.

[0004] The method of the present invention for synthesizing anatase/brookite nanocomposite materials used for photolysis of water to produce hydrogen by a one-step hydrothermal method is specifically operated as follows:

[0005] 1. Under stirring conditions, an alkali solution and a titanium source were added to the water solvent, and the stirring was continued for 30 minutes to obtain a precursor;

[0006] Wherein, the mass volume ratio of the titanium source to the water solvent is 1g: (15~30) mL, and the volume ratio of the alkali and the titanium source is 1: (0.4 to 3.4);

[0007] Second, the precursor obtained in step one is transferred to a hydrothermal kettle, placed in a blast drying box for hydrothermal reaction, the temperature is 120~160°C, and the reaction time is 10~24h;

[0008] Three, the product after the hydrothermal reaction in step two is washed first, and then ultrasonically dispersed in absolute ethanol; washing and ultrasonic dispersion are repeated twice to obtain the product; wherein, the washing conditions are: Centrifuge for 5 minutes under the condition of the centrifuge speed of 3000~4500r/min;

[0009] Four, the product obtained in step three is dried to obtain the final product; wherein; the drying process is: drying in a vacuum drying oven at a temperature of 30~60°C for 8~12h;

[0010] Fifth, the product obtained in step 4 is simmered at 500-900° C. under inert gas.

[0011] The present invention includes the following beneficial effects:

[0012] Compared with the prior art, the hydrothermal method used in the present invention has cheap raw materials, simple operation, low cost, high efficiency, and is easy for further industrial production. The resulting anatase/brookite nanocomposite material is prepared, Under ultraviolet light irradiation, the rate of photolysis of water to produce hydrogen can reach 50.5 μπιοί, which has a good effect of photolysis of water to produce hydrogen. It is further determined that the specific surface area of the relatively pure anatase titanium dioxide of the nanocomposite material has increased, reaching 55cm2/g. Compared with the currently existing synthesis-related photocatalyst, the nanocomposite material prepared by the method of the present invention It has a special shuttle morphology, and the surface area of pure anatase titanium dioxide is increased. Since the photocatalytic reaction mainly occurs on the surface of the photocatalyst, a relatively larger specific surface area can obviously promote the catalytic performance of the photocatalyst. The composition between the seed crystal phases changes the band gap of the composite material, accelerates electron transport, inhibits electron-hole recombination, and improves the photocatalytic hydrogen production rate.

Description of the drawings

[0013] FIG. 1 is an XRD pattern of the anatase/brookite nanocomposite material obtained in Example 1; wherein, it is the XRD of anatase and is the XRD of brookite;

[0014] FIG. 2 is a Raman diagram of the anatase/brookite nanocomposite material obtained in Example 1;

[0015] FIG. 3 is a transmission electron microscope picture of the anatase/brookite nanocomposite material obtained in Example 1;

[0016] FIG. 4 is a diagram showing the relationship between the amount of hydrogen produced by photolysis of water and the photocatalytic reaction time of the anatase/brookite nanocomposite obtained in Example 1;

[0017] FIG. 5 is a diagram showing the relationship between the amount of hydrogen produced by photolysis of water and the photocatalytic reaction time of the anatase/brookite nanocomposite material obtained in Example 2;

[0018] FIG. 6 is a diagram showing the relationship between the amount of hydrogen produced by photolysis of water and the photocatalytic reaction time of the anatase/brookite nanocomposite obtained in Example 3.

Detailed ways

[0019] The technical solution of the present invention is not limited to the specific embodiments listed below, and also includes any combination between the specific embodiments.

[0020] Specific Embodiment One: The method for synthesizing anatase/brookite nanocomposite materials for photolysis of water to produce hydrogen by a one-step hydrothermal method in this embodiment is specifically operated as follows:

[0021] 1. Under stirring conditions, an alkali solution and a titanium source were added to the water solvent, and the stirring was continued for 30 minutes to obtain a precursor;

[0022] Wherein, the mass-volume ratio of the titanium source and the water solvent is 1g: (15~30) mL, and the volume ratio of the alkali and the titanium source is 1: (0.4 to 3.4);

[0023] Second, the precursor obtained in step one is transferred to a hydrothermal kettle, placed in a blast drying box for hydrothermal reaction, the temperature is 120~160°C, and the reaction time is 10~24h;

[0024] Three, the product after the hydrothermal reaction in step two is washed first, and then ultrasonically dispersed in absolute ethanol; washing and ultrasonic dispersion are repeated twice to obtain the product; wherein, the washing conditions are: Centrifuge for 5 minutes under the condition of the centrifuge speed of 3000~4500r/min;

[0025] Four, the product obtained in step 3 is dried to obtain the final product; wherein the drying process is: drying in vacuum

Dry for 8-12h under the condition of 30~60°C in the box;

[0026] Fifth, the product obtained in step 4 is simmered at 500 to 900° C. under inert gas.

[0027] Compared with the prior art, the hydrothermal method used in this embodiment has cheap raw materials, simple operation, low cost, high efficiency, and is easy for further industrial production to prepare the resulting anatase/brookite nanocomposite material Under ultraviolet light irradiation, the rate of photolysis of water to produce hydrogen can reach 500. 5 ymol/h, which has a good effect of photolysis of water to produce hydrogen. After further testing, the specific surface area of the nanocomposite material can reach 55cm2/g. Compared with the currently existing synthesis-related photocatalysts, the nanocomposite material prepared by the method of this embodiment has a larger specific surface area. The reaction mainly takes place on the surface of the photocatalyst, so the smaller particle size and relatively larger specific surface area can obviously promote the catalytic performance of the photocatalyst.

[0028] Specific embodiment two: this embodiment is different from specific embodiment one in that: the feature described in step one is that the alkali is one or a mixed solution of one or more of hydrated lung, ammonia, rat amine, or hydroxylamine. Others are the same as the first embodiment.

[0029] Specific embodiment three: this embodiment is different from specific embodiment one or two in that the titanium source in step one is titanium oxysulfate, tetrabutyl titanate, titanium tetrachloride, titanium isopropoxide, One or a mixture of titanium sulfide and titanium tetrafluoride mixed in any ratio. Others are the same as the first or second embodiment.

[0030] Specific embodiment four: this embodiment is different from specific embodiments one to three in that the mass-volume ratio of the titanium source and the water solvent in step one is 1 g: (18-30) mL. Others and specific embodiments One to three is the same.

[0031] Specific embodiment five: this embodiment is different from one of specific embodiments one to four in that the mass-volume ratio of the titanium source and the water solvent in step one is 1 g: (20-30) mL. Others and specific embodiments One to four is the same.

[0032] Specific embodiment six: this embodiment is different from one of specific embodiments one to five in that the mass-volume ratio of the titanium source and the water solvent in step one is 1g: (22~30) mL. Others and specific embodiments One to five is the same.

[0033] Specific embodiment seven: this embodiment is different from one of specific embodiments one to six in that the mass-volume ratio of the titanium source and the water solvent in step one is 1 g: (25-30) mL. Others and specific embodiments One to six is the same.

[0034] Embodiment 8: This embodiment is different from one of Embodiments 1 to 7 in that the mass-volume ratio of the titanium source and the water solvent in step 1 is 1g: (28~30) mL. Others and specific embodiments One to seven is the same.

[0035] Embodiment 9: The difference between this embodiment and one of Embodiments 1 to 8 is that the mass-volume ratio of the titanium source and the water solvent in step 1 is 1g: (28~30) mL. Others and specific embodiments One to eight is the same.

[0036] Specific embodiment ten: This embodiment is different from one of specific embodiments one to nine in that the volume ratio of alkali and titanium source in step one is 1: (0.8~3.4). Others are the same as one of the first to ninth specific embodiments.

[0037] Specific embodiment eleven: this embodiment is different from specific embodiments one to eleven: the volume ratio of alkali and titanium source in step one is 1:(1.0-3.4). Others and specific embodiments One to eleven are the same.

[0038] Specific embodiment twelve: this embodiment is different from one of specific embodiments one to eleven: the volume ratio of alkali and titanium source in step one is 1: (1. 2-3.4). Others and specific implementation Same way from one to eleven.

[0039] Specific embodiment thirteen: This embodiment is different from one of specific embodiments 1 to 12 in that the volume ratio of alkali and titanium source in step 1 is 1: (1. 5-3.4). Others and specific implementations One of the ways from one to twelve is the same.

[0040] Specific embodiment fourteen: this embodiment is different from one of specific embodiments one to thirteen: the volume ratio of alkali and titanium source in step one is 1: (1. 8-3.4). Others and specific implementation The same way from one to one of the thirteenth.

[0041] Specific embodiment fifteen: This embodiment is different from one of specific embodiments one to fourteen: the volume ratio of alkali and titanium source in step one is 1: (2.0~3.4). Others are the same as one of specific embodiments one to fourteen.

[0042] Specific embodiment sixteen: this embodiment is different from one of specific embodiments one to fifteen: the volume ratio of alkali and titanium source in step one is 1: (2. 2~3.4). Others are the same as one of the first to fifteenth specific embodiments.

[0043] Specific embodiment seventeen: This embodiment is different from one of specific embodiments one to sixteen in that the volume ratio of alkali and titanium source in step one is 1: (2.4~3.4). Others are the same as one of specific embodiments 1 to 16.

[0044] Specific embodiment eighteen: this embodiment is different from one of specific embodiments one to seventeen in that the volume ratio of alkali and titanium source in step one is 1: (2.6~3.4). Others are the same as one of the specific embodiments one to seventeen.

[0045] Specific embodiment nineteen: this embodiment is different from one of specific embodiments one to eighteen: the volume ratio of alkali and titanium source in step one is 1: (2.8~3.4). Others are the same as one of specific embodiments 1 to 18.

[0046] Specific embodiment twenty: This embodiment is different from one of specific embodiments one to nineteen: the volume ratio of alkali and titanium source in step one is 1: (3.0~3.4). Others are the same as one of specific embodiments 1 to 19.

[0047] The specific embodiment two 4^ one: This embodiment is different from specific embodiments one to twenty one in that the volume ratio of the alkali and the titanium source in step one is 1: (3.2~3.4). Others are the same as the specific embodiments one to twenty one.

[0048] Specific embodiment 22: This embodiment is different from one of specific embodiments one to two 4^1: in step two, the reaction is carried out at a temperature of 160~180°C for 12~24ho. Others and specific embodiments One to two 4 is the same.

[0049] Embodiment 23: The difference between this embodiment and one of Embodiments 1 to 22 is that the washing conditions in step 3 are: centrifuge at 3000~4500r/min. 5min_oOthers are the same as one of specific embodiments one to twenty-two.

[0050] Specific embodiment twenty-four: the difference between this embodiment and one of specific embodiments one to twenty-third is: the drying process in step four is: drying in a vacuum drying oven at a temperature of 30 to 60°C 8~12h. Others are the same as one of specific embodiments 1 to 23.

IMPa. [0051] Specific embodiment twenty-five: This embodiment is different from one of specific embodiments one to twenty-four: the vacuum in the drying process in step four is 0~-0. IMPa. Others are the same as one of specific embodiments one to twenty-four.

[0052] Specific embodiment twenty-six: This embodiment is different from one of specific embodiments 1 to 25 in that: the simmering temperature in step 5 is any temperature in the range of 500 to 900°C. Others are the same as the first embodiment.

[0053] Specific embodiment twenty-seven: This embodiment is different from one of specific embodiments 1 to 26 in that the inert gas described in step 5 is one or several of nitrogen, gluten, and nitrogen Mix in any proportion. Others are the same as the first embodiment.

[0054] The following implementation cases are used to verify the beneficial effects of the present invention:

[0055] Embodiment One:

[0056] The preparation method of the anatase/brookite nanocomposite material used for photolysis of water to produce hydrogen of this embodiment is specifically carried out according to the following steps:

[0057] Measure 30mL of aqueous solution, add 4mL of hydration and 1g of titanyl sulfate dropwise at room temperature and stirring conditions, continue to stir for 30min to obtain the precursor; transfer the obtained precursor to a 45mL hydrothermal kettle, and place it in Reaction in a blast drying oven, the drying temperature is 150°C, and the hydrothermal time is 24h; the dried product is dispersed in ethanol, centrifuged, washed, and so on twice; the washed product is dried in a vacuum drying oven, The pressure is -0.1MPa, the temperature is 60°C, and the drying is for 10 hours. The final product is simmered at 600 degrees under an inert atmosphere, which is an anatase/brookite nanocomposite material used for photolysis of water to produce hydrogen.

[0058] The X-ray diffraction pattern of the anatase/brookite nanocomposite material obtained in this example is shown in FIG.

From Figure 1 we can know the characteristic diffraction peaks corresponding to anatase and brookite in the figure, which shows that an anatase/brookite composite material is formed.

[0059] The Raman diagram of the anatase/brookite nanocomposite material obtained in this embodiment is shown in FIG. 2, and the characteristic peak changes of the brookite can be seen through FIG. 2, indicating that the anatase/brookite Composite materials.

[0060] The transmission electron micrograph of the anatase/brookite nanocomposite material obtained in this embodiment is shown in FIG. 3, and it can be seen from FIG. 3 that the anatase/brookite composite material is a special shuttle shape. appearance.

[0061] The anatase/brookite nanocomposite material obtained in this example is shown in Figure 4 for the relationship between the amount of hydrogen produced by the photolysis of water and the photocatalytic reaction time. It can be seen from the figure that the anatase/brookite The nanocomposite material can produce 500.5 μ mol of hydrogen in 2.5 hours under ultraviolet light, and the performance is improved obviously.

[0062] The second embodiment:

[0063] The preparation method of anatase/brookite nanocomposite material used for photolysis of water to produce hydrogen of this embodiment is specifically carried out according to the following steps:

[0064] Measure 30mL of aqueous solution, add 4mL of hydration and 1g of titanyl sulfate dropwise at room temperature and stirring conditions, continue to stir for 30min to obtain a precursor; transfer the obtained precursor to a 45mL hydrothermal kettle, and place it in Reaction in a blast drying oven, the drying temperature is 150°C, and the hydrothermal time is 24h; the dried product is dispersed in ethanol, centrifuged, washed, and so on twice; the washed product is dried in a vacuum drying oven, The pressure is -0.1MPa, the temperature is 60°C, and the drying is for 10 hours. The final product is simmered at 500 degrees under an inert atmosphere, which is an anatase/brookite nanocomposite material used for photolysis of water to produce hydrogen.

[0065] The anatase/brookite nanocomposite material obtained in this example is shown in Figure 5 for the relationship between the amount of hydrogen produced by the photolysis of water and the photocatalytic reaction time. It can be seen from the figure that the anatase/brookite nanocomposite The nanocomposite material can produce 477.6 μ mol of hydrogen in 2.5 hours under ultraviolet light, and the performance is obviously improved.

[0066] Compared with the prior art, the hydrothermal method used in this embodiment has cheap raw materials, simple operation, low cost, high efficiency, and is easy for further industrial production to prepare the resulting anatase/brookite nanocomposite material , Under ultraviolet light irradiation, it has a good effect of photolysis of water to produce hydrogen. Compared with the existing synthesis-related photocatalysts, the nanocomposite material prepared by the method of this embodiment has a special shuttle morphology, and the surface area of the pure anatase titanium dioxide is increased. Because the photocatalytic reaction mainly occurs in light The surface of the catalyst, so the relatively larger specific surface area has a significant promotion effect on the catalytic performance of the photocatalyst. The composition between the two crystal phases changes the band gap of the composite material, accelerates electron transport, and inhibits electron-holes. The compound, thereby improving the photocatalytic hydrogen production rate.

[0067] Embodiment Three:

[0068] The preparation method of the anatase/brookite nanocomposite material used for photolysis of water to produce hydrogen of this embodiment is specifically carried out according to the following steps:

[0069] Measure 30mL of aqueous solution, add 4mL of hydrated lung and 0.5g of titanyl sulfate dropwise at room temperature and stirring conditions, continue to stir for 30min to obtain a precursor; transfer the obtained precursor to a 45mL hydrothermal kettle, Placed in a blast drying box for reaction, the drying temperature is 150°C, and the hydrothermal time is 24h; the dried product is dispersed in ethanol, centrifuged, washed, and so on twice; the washed product is dried and dried in vacuum The box has a pressure of -0.1MPa, a temperature of 60° C., drying for 10 hours, and simmering at 600 degrees under an inert atmosphere to obtain the final product, which is an anatase/brookite nanocomposite material used for photolysis of water to produce hydrogen.

[0070] The anatase/brookite nanocomposite material obtained in this example is shown in Figure 6 for the relationship between the amount of hydrogen produced by photolysis of water and the photocatalytic reaction time. It can be seen from the figure that the anatase/brookite Nanocomposite material under ultraviolet light, 2.5 hours

The hydrogen production reached 314.7 μ mol, and the performance was improved obviously.

[0071] Compared with the prior art, the hydrothermal method used in this embodiment has cheap raw materials, simple operation, low cost, high efficiency, and is easy for further industrial production to prepare the resulting anatase/brookite nanocomposite material , Under ultraviolet light irradiation, it has a good effect of photolysis of water to produce hydrogen. Compared with the existing synthesis-related photocatalysts, the nanocomposite material prepared by the method of this embodiment has a special shuttle morphology, and the surface area of the pure anatase titanium dioxide is increased. Because the photocatalytic reaction mainly occurs in light The surface of the catalyst, so the relatively larger specific surface area has a significant promotion effect on the catalytic performance of the photocatalyst. The composition between the two crystal phases changes the band gap of the composite material, accelerates electron transport, and inhibits electron-holes. The compound, thereby improving the photocatalytic hydrogen production rate.

[0072] The fourth embodiment:

[0073] The preparation method of the anatase/brookite nanocomposite material used for photolysis of water to produce hydrogen in this embodiment is specifically carried out according to the following steps:

[0074] Measure 30mL of aqueous solution, add 2mL of hydration and 1g of titanyl sulfate dropwise at room temperature and stirring conditions, continue to stir for 30min to obtain the precursor; transfer the obtained precursor to a 45mL hydrothermal kettle, and place it in Reaction in a blast drying oven, the drying temperature is 150°C, and the hydrothermal time is 24h; the dried product is dispersed in ethanol, centrifuged, washed, and so on twice; the washed product is dried in a vacuum drying oven, The pressure is -0.1MPa, the temperature is 60°C, and the drying is for 10 hours. The final product is simmered at 600 degrees under an inert atmosphere, which is an anatase/brookite nanocomposite material used for photolysis of water to produce hydrogen.

[0075] Compared with the prior art, the hydrothermal method used in this embodiment has cheap raw materials, simple operation, low cost, high efficiency, and is easy for further industrial production to prepare the resulting anatase/brookite nanocomposite material , Under ultraviolet light irradiation, it has a good effect of photolysis of water to produce hydrogen. Compared with the existing synthesis-related photocatalysts, the nanocomposite material prepared by the method of this embodiment has a special shuttle morphology, and the surface area of the pure anatase titanium dioxide is increased. Because the photocatalytic reaction mainly occurs in light The surface of the catalyst, so the relatively larger specific surface area has a significant promotion effect on the catalytic performance of the photocatalyst. The composition between the two crystal phases changes the band gap of the composite material, accelerates electron transport, and inhibits electron-holes. The compound, thereby improving the photocatalytic hydrogen production rate.