Ga2O3 powder with sea urchin morphology as well as preparation method and application of Ga2O3 powder

Abstract

The invention belongs to the technical field of photocatalytic materials, and discloses Ga2O3 powder with sea urchin morphology as well as a preparation method and application of the Ga2O3 powder. The microstructure of the Ga2O3 powder is in the shape of a sea urchin sphere, the Ga2O3 powder is self-assembled by taking a nano prism as a basic unit, and the preparation method of the Ga2O3 powder comprises the following steps: firstly, respectively preparing gallium nitrate hydrate and ammonia water into gallium ion microemulsion and ammonia water microemulsion, then dropwise adding the ammonia water microemulsion into the gallium ion microemulsion, heating and reacting to obtain precursor suspension liquid, and then preparing the Ga2O3 powder into the gallium ion microemulsion. And finally, carrying out solid-liquid separation on the precursor suspension, washing the solid, drying and calcining to obtain the Ga2O3 powder with the sea urchin morphology. The Ga2O3 powder with unique sea urchin morphology is prepared through an improved microemulsion-assisted precipitation method, and the Ga2O3 powder has high specific surface area and high light absorption capacity and has wide application prospects in the field of photocatalysis.

Description

Technical Field

[0001] The invention belongs to the technical field of photocatalytic materials, and in particular relates to a Ga2O3 powder with a sea urchin morphology, a preparation method and an application thereof. Background Art

[0002] With the continuous exploitation and burning of fossil energy, the energy crisis and environmental problems facing the earth are becoming increasingly serious. Fossil energy such as oil and natural gas are non-renewable, and one of their combustion products, CO2, is the main gas that causes the greenhouse effect. Therefore, it is urgent for humans to seek a technology that can solve both energy and environmental problems. As we all know, solar energy is clean, non-toxic, easily accessible and renewable. The currently published semiconductor photocatalytic CO2 reduction is a technology that can use solar energy to prepare various valuable chemical fuels. Photocatalytic CO2 reduction technology has become the most promising strategy to solve both energy crisis and environmental problems due to its low energy consumption, clean and non-toxic characteristics.

[0003] As a metal oxide semiconductor material, Ga2O3 has a more negative conduction band position than TiO2, ZnO and other semiconductor materials. Therefore, the excited photoelectrons of Ga2O3 have stronger CO2 reduction ability. In addition, Ga2O3 has 3d 10 Electronic configuration, this configuration in which the d orbital is completely occupied by electrons gives the photogenerated carriers a stronger separation and transmission ability. However, the rod-shaped gallium oxide prepared by existing precipitation method, hydrothermal method, combustion oxidation method and other technologies has problems such as low specific surface area, few active sites, and weak light absorption ability. Therefore, gallium oxide still exhibits poor photocatalytic CO2 reduction performance. In addition, the hydrothermal method involves a high temperature and high pressure reaction environment, which poses certain safety risks in the production process of large quantities of powders. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a Ga2O3 powder with sea urchin morphology and its preparation method and application in view of the shortcomings of the prior art. The Ga2O3 powder with unique sea urchin morphology is prepared by an improved microemulsion-assisted precipitation method. The powder has a high specific surface area and strong light absorption ability, and has broad application prospects in the field of photocatalysis.

[0005] In order to solve the technical problem proposed by the present invention, the present invention provides a method for preparing Ga2O3 powder with sea urchin morphology, comprising the following steps:

[0006] 1) dissolving gallium nitrate hydrate and gelatin in water to form a gallium ion aqueous solution, and then stirring evenly with n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol to obtain a gallium ion microemulsion;

[0007] 2) stirring ammonia water, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol to obtain an ammonia water microemulsion;

[0008] 3) Under stirring conditions, the ammonia water microemulsion is added dropwise to the gallium ion microemulsion until the pH reaches 8.5 to 9.5, and the addition is stopped. The stirring and heating reaction are continued to obtain a precursor suspension;

[0009] 4) The precursor suspension is subjected to solid-liquid separation to retain the solid matter, and the solid matter is washed, dried, and then calcined to obtain Ga2O3 powder with a sea urchin morphology.

[0010] In the above scheme, in the gallium ion aqueous solution, the mass ratio of gallium nitrate hydrate, gelatin and water is (0.2-0.22):(0.4-0.42):1.

[0011] In the above scheme, in step 1), the mass ratio of the gallium ion aqueous solution, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol is (1.75-1.82):(9.2-9.5):(1.1-1.2):1.

[0012] In the above scheme, the ammonia concentration in the ammonia water is 25-35%.

[0013] In the above scheme, in step 2), the mass ratio of ammonia water, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol is (1.75-1.82):(9.2-9.5):(1.1-1.2):1.

[0014] In the above scheme, the stirring rate of the stirring is 300-600r / min.

[0015] In the above scheme, the heating temperature of the heating reaction is 70-90° C., and the reaction time is 4-8 hours.

[0016] In the above scheme, the drying temperature is 60 to 90° C. and the drying time is 12 to 24 hours.

[0017] In the above scheme, the calcination temperature is 800-1000° C., and the calcination time is 2-4 hours.

[0018] In the above scheme, the particle size of the Ga2O3 powder is 3.5-5 μm, and the specific surface area is 40-45 m 2 / g.

[0019] The present invention also provides a Ga2O3 powder with a sea urchin morphology. The microscopic morphology of the Ga2O3 powder is a sea urchin sphere. The diameter of the sea urchin sphere is 3 to 6 μm. The powder is self-assembled with nanoprisms as basic units. The side length of the nanoprisms is 100 to 500 nm.

[0020] The present invention also provides an application of Ga2O3 powder with sea urchin morphology in photocatalytic reduction of CO2. The application method is: using Ga2O3 powder with sea urchin morphology as a photocatalyst, dispersing the photocatalyst in water, and reducing CO2 to CO under visible light irradiation.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention adopts a microemulsion-assisted precipitation method to prepare Ga2O3 powder, but due to the poor stability of micelles composed of gallium ion solution as an aqueous phase, the gallium ion microemulsion is unstable, which will lead to the generation of conventional rod-shaped gallium oxide powder. Therefore, the present invention introduces porcine gelatin into the gallium ion aqueous phase to increase the micelle viscosity, slow down the movement of microemulsion droplets and reduce their agglomeration rate, thereby achieving the preparation of a monodisperse and stable gallium ion microemulsion; in addition, the present invention also prepares ammonia water into a microemulsion, and constructs a double microemulsion system to maximize the prevention of the stability of the gallium ion microemulsion from being destroyed during the aging reaction, and avoids the problem that the local hydroxide concentration is too high when the precipitant is directly added, resulting in the material morphology not being able to grow uniformly or the appearance of a traditional rod-shaped structure; in summary, the Ga2O3 powder is prepared by the improved microemulsion-assisted precipitation method, so that the Ga2O3 powder presents a unique sea urchin morphology, which not only gives the Ga2O3 powder a high specific surface area, but also improves the light absorption capacity during photocatalytic reduction of CO2, showing excellent CO production, and has broad application prospects in the field of photocatalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The SEM image (left) and high-resolution TEM image (right) of the product obtained in Example 1.

[0024] Figure 2 The nitrogen isothermal adsorption-desorption isotherm spectrum of the product obtained in Example 1.

[0025] Figure 3 The XRD pattern of the product obtained in Example 1 is shown in FIG.

[0026] Figure 4 This is the SEM picture of the product obtained in Comparative Example 1.

[0027] Figure 5 This is the SEM picture of the product obtained in Comparative Example 2. DETAILED DESCRIPTION

[0028] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0029] Example 1

[0030] In this embodiment, the Ga2O3 powder with sea urchin morphology is as follows: Figure 1 As shown, the microscopic morphology of the Ga2O3 powder is in the shape of a sea urchin ball with a diameter of 5 to 5.5 μm. The powder is self-assembled with nanoprisms as basic units, and the side length of the nanoprisms is 100 to 400 nm.

[0031] The preparation method of Ga2O3 powder with sea urchin morphology in this embodiment comprises the following steps:

[0032] 1) dissolving gallium nitrate hydrate and porcine gelatin powder in water to form a gallium ion aqueous solution, wherein the mass ratio of gallium nitrate hydrate, gelatin and water is 0.2:0.4:1, and mixing the gallium ion aqueous solution, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol in a mass ratio of 1.75:9.2:1.1:1 and stirring to obtain a gallium ion microemulsion;

[0033] 2) mixing ammonia water with an ammonia concentration of 30%, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol in a mass ratio of 1.75:9.2:1.1:1 and stirring evenly to obtain an ammonia water microemulsion;

[0034] 3) Under stirring at 400 r / min, the ammonia water microemulsion was added dropwise to the gallium ion microemulsion until the pH reached 9, and the addition was stopped. The mixture was stirred and heated at 90° C. for 6 h to obtain a precursor suspension;

[0035] 4) The precursor suspension is placed in a suction funnel for suction filtration, and ethanol and deionized water are added for washing and repeated filtration. The obtained solid is placed in a vacuum drying oven and dried at 60°C for 24 hours, and then transferred to a muffle furnace for calcination at a calcination temperature of 900°C and a calcination time of 3 hours. The calcined product is ground until it has a fine texture to obtain Ga2O3 powder with a sea urchin morphology.

[0036] Figure 1 The SEM image (left) and high-resolution TEM image (right) of the product obtained in this example are shown in FIG. Figure 1 (Left) It can be confirmed that its sea urchin structure, Figure 1 (Right) It can be seen that the lattice fringe spacing of the sea urchin structure powder is 0.241, 0.240, and 0.257 nm, corresponding to the (-311), (401), and (111) crystal planes of Ga2O3, respectively, thus confirming that it is sea urchin morphology Ga2O3.

[0037] Figure 2 The nitrogen isotherm adsorption-desorption isotherm of the product obtained in this example shows a type IV isotherm adsorption line, confirming that its BET specific surface area is 44.7 m 2 / g.

[0038] Figure 3This is the XRD spectrum of the product obtained in this example. All diffraction peaks can correspond to the diffraction peaks of the standard gallium oxide card, and the half-peak width of the diffraction peak is narrow, which confirms the synthesis of high-crystallinity Ga2O3 powder.

[0039] Example 2

[0040] The preparation method of Ga2O3 powder with sea urchin morphology in this embodiment comprises the following steps:

[0041] 1) dissolving gallium nitrate hydrate and porcine gelatin powder in water to form a gallium ion aqueous solution, wherein the mass ratio of gallium nitrate hydrate, gelatin and water is 0.21:0.41:1, and mixing the gallium ion aqueous solution, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol in a mass ratio of 1.8:9.4:1.15:1 and stirring to obtain a gallium ion microemulsion;

[0042] 2) mixing ammonia water with an ammonia concentration of 25%, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol in a mass ratio of 1.8:9.4:1.15:1 and stirring evenly to obtain an ammonia water microemulsion;

[0043] 3) Under stirring conditions of 500 r / min, the ammonia water microemulsion was added dropwise to the gallium ion microemulsion until the pH reached 8.5, and the addition was stopped. The mixture was stirred and heated at 80° C. for 4 h to obtain a precursor suspension;

[0044] 4) The precursor suspension is placed in a suction funnel for suction filtration, and ethanol and deionized water are added for washing and repeated filtration. The obtained solid is placed in a vacuum drying oven and dried at 70°C for 20 hours, and then transferred to a muffle furnace for calcination at a calcination temperature of 800°C and a calcination time of 4 hours. The calcined product is ground until it has a fine texture to obtain Ga2O3 powder with a sea urchin morphology.

[0045] Example 3

[0046] The preparation method of Ga2O3 powder with sea urchin morphology in this embodiment comprises the following steps:

[0047] 1) dissolving gallium nitrate hydrate and porcine gelatin powder in water to form a gallium ion aqueous solution, wherein the mass ratio of gallium nitrate hydrate, gelatin and water is 0.22:0.42:1, and mixing the gallium ion aqueous solution, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol in a mass ratio of 1.82:9.5:1.2:1 and stirring to obtain a gallium ion microemulsion;

[0048] 2) mixing ammonia water with an ammonia concentration of 35%, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol in a mass ratio of 1.82:9.5:1.2:1 and stirring to obtain an ammonia water microemulsion;

[0049] 3) Under stirring conditions of 600 r / min, the ammonia water microemulsion was added dropwise to the gallium ion microemulsion until the pH reached 9.5, and the addition was stopped. The mixture was stirred and heated at 70° C. for 8 h to obtain a precursor suspension;

[0050] 4) The precursor suspension is placed in a suction funnel for suction filtration, and ethanol and deionized water are added for washing and repeated filtration. The obtained solid is placed in a vacuum drying oven and dried at 90°C for 16 hours, and then transferred to a muffle furnace for calcination at a calcination temperature of 1000°C for 2 hours. The calcined product is ground until it has a fine texture to obtain Ga2O3 powder with a sea urchin morphology.

[0051] Comparative Example 1

[0052] The only difference between Comparative Example 1 and Example 1 is that no porcine gelatin powder is added.

[0053] Figure 4 This is the SEM picture of the product obtained in this comparative example, from which it can be seen that its morphology is rod-shaped.

[0054] Comparative Example 2

[0055] The only difference between Comparative Example 2 and Example 1 is that the ammonia water is not prepared into an ammonia water microemulsion, but the ammonia water is directly added dropwise to the gallium ion microemulsion.

[0056] Figure 5 This is the SEM picture of the product obtained in this comparative example. It can be seen from the figure that its morphology is rice grain-like and has serious agglomeration.

[0057] Application Examples

[0058] The Ga2O3 powders prepared in Examples 1 to 3 and Comparative Examples 1 to 2 and commercial rod-shaped Ga2O3 powders were respectively used for photocatalytic reduction of CO2. The application method was as follows: using Ga2O3 powder as a photocatalyst, 15 mg of the photocatalyst was dispersed in 5 mL of water and placed in a 100 mL reactor. CO2 gas was introduced into the reactor for 40 minutes, and then a 300 W mercury lamp was used to irradiate the reactor. Under the irradiation of the mercury lamp, the photocatalyst reduced CO2 to CO. After 1 hour of irradiation, the gas was collected and the CO production was analyzed by gas chromatograph.

[0059] Table 1

[0060] sample Particle size (μm) <![CDATA[Specific surface area (m 2 / g)]]> CO production (μmol / g / h) Example 1 4.3 44.7 47.31 Example 2 4.2 41.5 44.56 Example 3 3.8 43.6 45.28 Comparative Example 1 1.7 15.2 21.48 Comparative Example 2 1.9 12.4 19.53 <![CDATA[Commercial Ga2O3]]> 2.2 8.7 12.45

[0061] According to the test results in Table 1, it can be found that the Ga2O3 powder with sea urchin morphology prepared in the embodiment of the present invention has a high specific surface area and has obvious yield advantages in photocatalytic CO2 reduction to CO; while the commercial rod-shaped Ga2O3 powder has a low specific surface area, few active sites, and weak light absorption capacity, showing poor photocatalytic CO2 reduction performance; in Comparative Example 1, since no porcine gelatin powder was added, the gallium ion microemulsion was unstable, resulting in the formation of conventional rod-shaped gallium oxide powder, causing significant performance degradation; in Comparative Example 2, since the ammonia water was not prepared into a microemulsion and the ammonia water was directly added, the local hydroxide concentration was too large, resulting in the morphology of the material not being able to grow uniformly, and the traditional rod-shaped structure appeared, thereby significantly reducing the performance.

[0062] The above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above descriptions. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims

1. A Ga with sea urchin morphology 2 O 3 Powder, It is characterized in that The Ga 2 O 3 The microscopic morphology of the powder is in the shape of a sea urchin ball, the diameter of the sea urchin ball is 3-6 μm, and the powder is self-assembled with nano prisms as basic units, and the side length of the nano prisms is 100-500 nm.

2. The Ga with sea urchin morphology according to claim 1 2 O 3 Powder, It is characterized in that The Ga 2 O 3 The particle size of the powder is 3.5 to 5 μm, and the specific surface area is 40 to 45 m 2 / g.

3. A Ga with sea urchin morphology as claimed in claim 1 or 2 2 O 3 Method for preparing powder, It is characterized in that The following steps are involved: 1) dissolving gallium nitrate hydrate and gelatin in water to form a gallium ion aqueous solution, and then stirring evenly with n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol to obtain a gallium ion microemulsion; 2) stirring ammonia water, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol to obtain an ammonia water microemulsion; 3) Under stirring conditions, the ammonia water microemulsion is added dropwise to the gallium ion microemulsion until the pH reaches 8.5 to 9.5, and the addition is stopped. The stirring and heating reaction are continued to obtain a precursor suspension; 4) The precursor suspension is subjected to solid-liquid separation to retain the solid matter, and the solid matter is washed, dried, and then calcined to obtain Ga with sea urchin morphology. 2 O 3 Powder.

4. The Ga with sea urchin morphology according to claim 3 2 O 3 Method for preparing powder, It is characterized in that In the gallium ion aqueous solution, the mass ratio of gallium nitrate hydrate, gelatin and water is (0.2-0.22):(0.4-0.42):

1.

5. The Ga with sea urchin morphology according to claim 3 2 O 3 Method for preparing powder, It is characterized in that In step 1), the mass ratio of the gallium ion aqueous solution, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol is (1.75-1.82):(9.2-9.5):(1.1-1.2):

1.

6. The Ga with sea urchin morphology according to claim 3 2 O 3 Method for preparing powder, It is characterized in that In step 2), the mass ratio of ammonia water, n-dodecane, hexadecyltrimethylammonium bromide and n-hexanol is (1.75-1.82):(9.2-9.5):(1.1-1.2):1, and the ammonia concentration in the ammonia water is 25-35%.

7. The Ga with sea urchin morphology according to claim 3 2 O 3 Method for preparing powder, It is characterized in that The heating temperature of the heating reaction is 70-90° C., and the reaction time is 4-8 hours.

8. The Ga with sea urchin morphology according to claim 3 2 O 3 Method for preparing powder, It is characterized in that The calcination temperature is 800-1000° C., and the calcination time is 2-4 hours.

9. The Ga with sea urchin morphology according to claim 3 2 O 3 Method for preparing powder, It is characterized in that The stirring rate of the stirring is 300-600 r / min; the drying temperature is 60-90° C., and the drying time is 12-24 hours.

10. A Ga with sea urchin morphology as claimed in claim 1 or 2 2 O 3 Powder in photocatalytic reduction of CO 2 Application in.

Images