Indium selenide / tin selenide binary heterojunction nanomaterial and preparation method and application thereof

Abstract

The application discloses an indium selenide / tin selenide binary heterojunction nanomaterial and a preparation method and application thereof. The preparation method is as follows: dispersing selenium powder I and polyvinylpyrrolidone in water, then adding hydrazine hydrate and stannous chloride in sequence, mixing and stirring, and then performing hydrothermal reaction to obtain SnSe nanosheets; dispersing the SnSe nanosheets in triethylene glycol, then adding indium tetrachloride and selenium powder II in sequence, mixing and stirring, and then performing solvothermal reaction, and the binary heterojunction nanomaterial is obtained. The binary heterojunction nanomaterial has excellent catalytic performance and high cycle stability, and has a good removal effect on organic and inorganic pollutants. The preparation method is simple, low in cost and convenient to operate.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of nanomaterials, specifically to a kind of indium selenide / tin selenide binary heterojunction nanomaterial, also relates to its preparation method and application, belongs to catalyst material and environmental protection technical field. BACKGROUND

[0002] Environmental pollution and clean energy shortage is one of the most pressing problems threatening the sustainable development of human civilization, the development of industry has caused a lot of environmental pollution. The accumulation of various pollutants in air, soil and water is threatening the natural environment, and at present, the treatment of environmental pollution is urgent. Among the repair methods used, advanced oxidation processes (AOPs) are a class of technologies based on in-situ generation of highly active oxidative radicals, which can destroy most pollutants. Photocatalysis is one of the most widely studied areas of AOPs, in which semiconductors with suitable band gaps can effectively absorb light and form photo-generated electron-hole pairs. Then, these electrons and holes can migrate to the surface of the photocatalyst and undergo oxidation / reduction processes. Because there is sufficient solar energy in some areas, this makes it possible to use semiconductor photocatalysts to remove environmental pollutants. However, low carrier mobility and rapid electron-hole pair recombination are common problems that limit semiconductor photocatalysis, in order to overcome this problem researchers have proposed new strategies, such as using wide band gap semiconductors, such as titanium dioxide (TiO2), developing new nanostructures, using cocatalysts (Pt, Pd and RuO2), doping rare earth or transition metals, etc., although these methods can improve the separation efficiency of photo-generated electrons and holes, they are largely dependent on the use of expensive catalysts such as noble metals, and are subject to complex manufacturing processes. In addition to chemically modifying wide band gap semiconductors, physical methods such as applying an external electric field to electrochemical cells are also used to separate electron / hole pairs, although this method has shown great potential in improving photocatalytic efficiency, its high cost, complex device structure and difficult operating conditions pose major challenges for practical applications. Generating a local electric field directly on the surface of the photocatalyst has the advantages of low cost and low energy consumption, and is more practical compared to applying a macroscopic electric field in a chemical cell.

[0003] Combining piezoelectric materials with visible light photocatalysts is one way to achieve this goal. Piezoelectric materials can generate an internal electric field under strain, thereby inducing the separation of photo-generated charges, in this method, the reaction efficiency can be improved by using the dual effect of light and mechanical vibration, enhancing the degradation capacity. Therefore, it is of great research significance and application value to construct a new type of catalyst that can couple photocatalysis and piezoelectric catalysis, and there is also great expectation for the repair of environmental pollution through green technology, such as using natural resources such as natural sunlight and waste energy such as noise and vibration, to achieve efficient application for environmental repair. SUMMARY

[0004] To address the shortcomings of existing technologies, such as high catalyst material cost, limited catalytic performance, low catalytic efficiency, poor cycle stability, complex device structure, and difficult operating conditions, the first objective of this invention is to provide an indium selenide / tin selenide binary heterojunction nanomaterial. This material exhibits excellent catalytic performance and good cycle stability.

[0005] The second objective of this invention is to provide a method for preparing indium selenide / tin selenide binary heterojunction nanomaterials. This method is simple, low-cost, and suitable for industrial-scale production.

[0006] A third objective of this invention is to provide an application of an indium selenide / tin selenide binary heterojunction nanomaterial. This material, under the combined effects of light and mechanical vibration, can improve reaction efficiency, significantly enhance its catalytic degradation ability of organic pollutants, and exhibit good cycle stability.

[0007] To achieve the above-mentioned technical objectives, this invention provides a method for preparing indium selenide / tin selenide binary heterojunction nanomaterials. The method involves dispersing selenium powder I and polyvinylpyrrolidone in water, then sequentially adding hydrazine hydrate and stannous chloride, mixing and stirring, and then carrying out a hydrothermal reaction to obtain SnSe nanosheets; dispersing the SnSe nanosheets in triethylene glycol, then sequentially adding indium tetrachloride and selenium powder II, mixing and stirring, and then carrying out a solvothermal reaction to obtain the final product.

[0008] As a preferred embodiment, the mass ratio of selenium powder I to polyvinylpyrrolidone is 1:1 to 20. Controlling the mass ratio of selenium powder to polyvinylpyrrolidone within a suitable range is beneficial for obtaining nanosheets with excellent performance. If the ratio is too low, the prepared nanosheets will have uneven morphology and size, while if the ratio is too high, the yield will be relatively reduced.

[0009] As a preferred embodiment, the volume ratio of hydrazine hydrate to water is 1:5 to 10.

[0010] As a preferred embodiment, the molar ratio of stannous chloride to selenium powder I is 1:1 to 1.3.

[0011] As a preferred embodiment, the hydrothermal reaction conditions are: temperature of 100–150°C and time of 16–24 hours.

[0012] As a preferred embodiment, the molar ratio of indium tetrachloride to SnSe is 1:2 to 5. Controlling the molar ratio of indium tetrachloride to SnSe within a suitable range can yield a catalyst material with superior performance; a ratio that is too high or too low will result in a relative decrease in performance.

[0013] As a preferred embodiment, the molar ratio of selenium powder II to indium tetrachloride is 0.3–1.2:1. Controlling the molar ratio of selenium powder II to indium tetrachloride within a suitable range can yield a catalyst material with superior performance; a ratio that is too high or too low will result in a relative decrease in performance.

[0014] As a preferred embodiment, the conditions for the solvothermal reaction are: a temperature of 160–220°C and a time of 12–28 h.

[0015] This invention also provides an indium selenide / tin selenide binary heterojunction nanomaterial, which is prepared by the above method. This material exhibits excellent catalytic performance and good cycle stability.

[0016] As a preferred embodiment, the mass ratio of tin selenide to indium selenide in the binary heterojunction nanomaterial is 0.95–0.4:0.05–0.6, more preferably 0.8–0.5:0.2–0.5. The binary heterojunction nanomaterial with this composite ratio exhibits excellent catalytic performance.

[0017] This invention also provides an application of indium selenide / tin selenide binary heterojunction nanomaterials, which are used for the catalytic degradation of organic pollutants and the catalytic reduction of inorganic pollutants. This material exhibits high removal efficiency for both organic and inorganic pollutants.

[0018] As a preferred embodiment, the mass ratio of the indium selenide / tin selenide binary heterojunction nanomaterial to the pollutant is 20-50:1-50.

[0019] As a preferred embodiment, the concentration of the pollutant is 5–100 mg / L.

[0020] As a preferred embodiment, during the catalytic application process, the pH value of the solution system is controlled to be 3-6, more preferably 3.5-5.

[0021] As a preferred embodiment, the temperature of the solution system is controlled to be between 0 and 40°C during the catalytic application process.

[0022] As a preferred embodiment, the setup of the catalytic application device includes the following steps:

[0023] 1) After mixing the indium selenide / tin selenide binary heterojunction nanomaterial with the contaminant solution, place it in a sealed glass container;

[0024] 2) Secure the sealed glass container to the ultrasonic machine, ensuring that the liquid level inside the container is lower than the liquid level in the ultrasonic machine;

[0025] 3) Shine the xenon lamp light source vertically onto the liquid surface in the glass container, with the xenon lamp light source 10-20cm away from the liquid surface in the glass container.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The binary heterojunction nanomaterial has excellent catalytic performance and good cycle stability;

[0028] (2) It can make full use of natural resources such as natural light and waste energy such as noise and vibration to improve catalytic efficiency, significantly enhance the catalytic degradation capacity of organic pollution, and achieve efficient application for environmental remediation.

[0029] (3) Binary heterojunction nanomaterials are not limited to the combination of In2Se3 and SnSe, but can be replaced by other elements of the same group, which provides ideas and theoretical basis for the preparation of new catalysts.

[0030] (4) The preparation method is simple and the cost is low. No load equipment is required when applying it, making it suitable for industrial production. Attached Figure Description

[0031] Figure 1 The image shows a SEM image of the nanocatalyst material prepared in Example 1.

[0032] Figure 2 This is a TEM image of the binary heterojunction nanomaterial prepared in Example 1.

[0033] Figure 3 The image shows a comparison of the performance of the binary heterojunction nanomaterials, SnSe materials, and In2Se3 materials prepared in Example 1 in catalytic degradation of tetracycline.

[0034] Figure 4 The graph shows a comparison of the performance of binary heterojunction nanomaterials, SnSe materials, and In2Se3 materials prepared in Examples 1-6 in catalytic degradation of tetracycline.

[0035] Figure 5 The graph shows a comparison of the performance of the binary heterojunction nanomaterials, SnSe materials, and In2Se3 materials prepared in Example 1 for the catalytic reduction of uranyl nitrate.

[0036] Figure 6 The graph shows a comparison of the performance of the binary heterojunction nanomaterials, SnSe materials, and In2Se3 materials prepared in Example 1 in degrading Rhodamine B.

[0037] Figure 7 The graph shows a comparison of the performance of the binary heterojunction nanomaterials, SnSe materials, and In2Se3 materials prepared in Example 1 in degrading methylene blue. Detailed Implementation

[0038] The specific embodiments of the invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] Example 1

[0040] The following is a preparation process of an indium selenide / tin selenide binary heterojunction nanomaterial according to the present invention. The specific steps are as follows:

[0041] Step 1: Disperse 156 mg of selenium powder and 15 mg of polyvinylpyrrolidone in 80 mL of deionized water.

[0042] Step 2: Add 5 mL of hydrazine hydrate to the solution from Step 1 and keep stirring for 30 minutes.

[0043] Step 3: Add 451 mg of stannous chloride dihydrate to the solution from Step 2 and stir for 30 minutes.

[0044] Step 4: Pour the solution obtained in Step 3 into a hydrothermal reactor and place it in a forced-air drying oven to react at 130°C for 24 hours.

[0045] Step 5: The black precipitate with metallic luster obtained from the reaction was washed by centrifugation at 8000 rpm with deionized water and ethanol respectively. The supernatant was carefully removed, and the precipitate was placed in a vacuum oven at 60°C overnight to obtain SnSe nanosheet material.

[0046] Step 6: Disperse the above 70 mg SnSe nanosheet material in 80 mL triethylene glycol by ultrasonic treatment.

[0047] Step 7: Add 28.4 mg of anhydrous indium tetrachloride to the solution from step 6, dissolve completely and stir for 30 minutes.

[0048] Step 8: Add 15.2 mg of selenium powder to the solution from Step 7 and stir for 3 hours.

[0049] Step 9: Pour the solution obtained in Step 8 into a hydrothermal reactor and place it in a forced-air drying oven to react at 180°C for 24 hours.

[0050] Step 10: Collect the red and black precipitate in the reactor and wash it with deionized water and ethanol at 10,000 rpm. Carefully remove the supernatant and place the precipitate in a vacuum oven at 60°C overnight. The nanomaterial prepared under these conditions is denoted as 0.7SnSe-0.3In2Se3.

[0051] Comparative Example 1

[0052] SnSe nanosheets were prepared using steps 1 to 5 of the method in Example 1.

[0053] Comparative Example 2

[0054] The specific steps for preparing indium selenide (In2Se3) nanosheets are as follows:

[0055] Step 1: Disperse 88 mg of anhydrous indium tetrachloride in 80 mL of triethylene glycol by ultrasonic treatment.

[0056] Step 2: Add 47 mg of selenium powder to the solution from Step 1 and stir for 3 hours.

[0057] Step 3: Pour the solution obtained in Step 2 into a hydrothermal reactor and place it in a forced-air drying oven to react at 200°C for 24 hours.

[0058] Step 4: Collect the reddish-brown precipitate in the reactor and wash it with deionized water and ethanol at 10,000 rpm. Carefully remove the supernatant and place the precipitate in a vacuum oven at 60°C overnight to obtain indium selenide nanosheets.

[0059] The binary heterojunction nanomaterials prepared in Example 1, the SnSe nanosheets of Comparative Example 1, and the In2Se3 nanosheets of Comparative Example 2 were characterized and tested, such as... Figure 1 and Figure 2 As shown, where, Figure 1 a is a scanning electron microscope image of SnSe nanosheets; Figure 1 b is a scanning electron microscope image of In2Se3 nanosheets; Figure 1 c is a scanning electron microscope image of 0.7SnSe-0.3In2Se3 binary heterojunction nanoflowers. It can be seen that the prepared binary heterojunction has a relatively uniform morphology and a more uniform structure than pure SnSe and In2Se3 nanosheets. Figure 2 a is a transmission electron microscope image of a 0.7SnSe-0.3In2Se3 binary heterojunction, and... Figure 1 c. The SEM morphology remains consistent; Figure 2 b is a high-resolution transmission electron microscope image of the 0.7SnSe-0.3In2Se3 binary heterostructure, which shows that the binary heterostructure has good crystallinity. Figure 2 c is a high-angle annular dark-field scanning transmission electron microscope image of a 0.7SnSe-0.3In2Se3 binary heterojunction; Figure 2 Images d to 2f show the elemental distribution of the 0.7SnSe-0.3In2Se3 binary heterojunction. The distribution of In, Sn, and Se can be clearly seen, proving that the binary heterojunction is composed of these three elements.

[0060] Example 2

[0061] The In2Se3@SnSe binary heterojunction nanomaterial was prepared using the method of Example 1, with the following differences: the amount of SnSe added in step 6 was 80 mg, the amount of anhydrous indium chloride added in step 7 was 19.2 mg, and the amount of selenium powder added in step 8 was 10.1 mg. The nanomaterial prepared under these conditions is denoted as 0.8SnSe-0.2In2Se3.

[0062] Example 3

[0063] The In2Se3@SnSe binary heterojunction nanomaterial was prepared using the method of Example 1, with the following differences: the amount of SnSe added in step 6 was 20 mg, the amount of anhydrous indium chloride added in step 7 was 75.8 mg, and the amount of selenium powder added in step 8 was 40.6 mg. The nanomaterial prepared under these conditions is denoted as 0.2SnSe-0.8In2Se3.

[0064] Example 4

[0065] The In2Se3@SnSe binary heterojunction nanomaterial was prepared using the method of Example 1, with the following differences: the amount of SnSe added in step 6 was 95 mg, the amount of anhydrous indium chloride added in step 7 was 4.7 mg, and the amount of selenium powder added in step 8 was 2.5 mg. The nanomaterial prepared under these conditions is denoted as 0.95SnSe-0.05In2Se3.

[0066] Example 5

[0067] The In2Se3@SnSe binary heterojunction nanomaterial was prepared using the method of Example 1, with the following differences: the amount of SnSe added in step 6 was 50 mg, the amount of anhydrous indium chloride added in step 7 was 47.1 mg, and the amount of selenium powder added in step 8 was 38 mg. The nanomaterial prepared under these conditions is denoted as 0.5SnSe-0.5In2Se3.

[0068] Example 6

[0069] The In2Se3@SnSe binary heterojunction nanomaterial was prepared using the method of Example 1, with the following differences: the amount of SnSe added in step 6 was 40 mg, the amount of anhydrous indium chloride added in step 7 was 56.9 mg, and the amount of selenium powder added in step 8 was 30.4 mg. The nanomaterial prepared under these conditions is denoted as 0.4SnSe-0.6In2Se3.

[0070] Example 7

[0071] The catalytic performance of the nanomaterials prepared in Examples 1-6 and Comparative Examples 1-2 was tested, and the steps for building the application device are as follows:

[0072] 1) Add 40 mg of nanomaterial to 100 mL of tetracycline solution with a concentration of 30 mg / L and stir until homogeneous, then transfer to a sealed glass container;

[0073] 2) Fix the sealed glass container described above into any type of ultrasonic machine, keeping the liquid level in the container lower than the liquid level in the ultrasonic machine;

[0074] 3) Shine the xenon lamp light source vertically onto the liquid surface of the glass container, keeping the xenon lamp light source 10-20cm away from the liquid surface.

[0075] In this catalytic process, the system temperature was controlled at 20℃, and the pH value of the solution system was adjusted to 3-6 to test the catalytic performance of the material. Figure 3 As shown, tetracycline eventually degrades into carbon dioxide and water.

[0076] Figure 3 a-3b shows the catalytic degradation activity and degradation rate of tetracycline, an organic pollutant, by single and composite materials under light, ultrasound, and two different modes. It can be clearly seen from the figure that the composite material has a very strong degradation ability of tetracycline under the light + ultrasound mode. Figure 3 c-3d investigated the effect of different pH values ​​on the catalytic degradation activity and degradation rate of the composite material under light + ultrasound mode (catalyst dosage was 40 mg). It can be clearly seen that the composite material exhibits good catalytic activity in the pH range of 3 to 6, and has a wide range of applications. Figure 3 e-3f investigated the effect of the amount of composite material on catalytic degradation activity and degradation rate in light + ultrasound mode (solution system pH=5). It can be clearly seen that the composite material has good degradation ability in the range of 20-50mg. Figure 3 g represents the stability test of the composite material during 5 cycles of catalytic degradation. It can be clearly seen that the composite material has excellent cycle stability and broad application prospects.

[0077] Figure 4 To investigate the catalytic degradation activity (4a) and degradation rate (4b) of composite materials with different SnSe and In2Se3 contents for the organic pollutant tetracycline under both light and ultrasonic modes, the following studies were conducted. Figure 4 It can be seen that when the mass ratio of SnSe to In2Se3 is 0.8:0.2 to 0.5:0.5, the degradation activity and degradation rate of the composite material are relatively high. When the SnSe content is higher than 80% or lower than 50%, the catalytic performance of the composite material is relatively reduced, but it is still significantly better than that of single SnSe material or In2Se3 material.

[0078] Example 8

[0079] The catalytic performance was tested using the apparatus of Example 7, except that the pollutant was the inorganic pollutant uranyl nitrate (concentration of 30 mg / L) and the amount of catalyst was 30 mg.

[0080] During this catalytic process, the pH value of the solution system was controlled within the range of 2.5-5.5 to test the catalytic performance of the material. Figure 5 As shown, uranyl nitrate is eventually reduced to (UO2)O2·2H2O.

[0081] Figure 5 a-5b shows the catalytic degradation activity and degradation rate of the inorganic pollutant uranyl nitrate by single and composite materials under light, ultrasound and two other modes. It can be clearly seen that the composite material has a very strong degradation ability of pollutants under the light + ultrasound mode. Figure 5 c-5d investigated the effects of different pH values ​​on the catalytic degradation activity and degradation rate of the composite material under light and ultrasound mode. It can be clearly seen that the composite material exhibits good catalytic activity in the pH range of 2.5-5.5, and has a broad application prospect.

[0082] Example 9

[0083] The catalytic performance was tested using the apparatus of Example 7, except that the pollutant was the organic pollutant Rhodamine B (concentration of 30 mg / L) and the amount of catalyst was 30 mg.

[0084] In this catalytic process, the system temperature was controlled at 20℃ and the pH value of the solution system was 4, in order to test the catalytic performance of the material, such as... Figure 6 As shown, Rhodamine B eventually degrades into carbon dioxide and water.

[0085] Figure 6 a-6b shows the catalytic degradation activity and degradation rate of the organic pollutant Rhodamine B by single and composite materials under light + ultrasound mode. It can be clearly seen that the composite material has a very strong degradation ability of Rhodamine B under light + ultrasound mode.

[0086] Example 10

[0087] The catalytic performance was tested using the apparatus of Example 7, except that the pollutant was the organic pollutant methylene blue (concentration of 30 mg / L) and the amount of catalyst was 30 mg.

[0088] In this catalytic process, the system temperature was controlled at 20℃ and the pH value of the solution system was 4, in order to test the catalytic performance of the material, such as... Figure 7 As shown, methylene blue eventually degrades into carbon dioxide and water.

[0089] Figure 7a-7b shows the catalytic degradation activity and degradation rate of the organic pollutant methylene blue in single and composite materials under light + ultrasound mode. It can be clearly seen that the synthesized composite material has a very strong degradation ability of methylene blue under light + ultrasound mode.

Claims

1. A method for preparing indium selenide / tin selenide binary heterojunction nanomaterials, characterized in that: Selenium powder I and polyvinylpyrrolidone were dispersed in water, and then hydrazine hydrate and stannous chloride were added sequentially and stirred before hydrothermal reaction to obtain SnSe nanosheets; the SnSe nanosheets were dispersed in triethylene glycol, and then indium tetrachloride and selenium powder II were added sequentially and stirred before solvothermal reaction to obtain the final product. The molar ratio of stannous chloride to selenium powder I is 1:1~1.2; The molar ratio of indium tetrachloride to tin selenide is 1:2~5; The molar ratio of selenium powder II to indium tetrachloride is 0.3~1.2:1; The conditions for the hydrothermal reaction are: temperature 100~150℃, time 16~24h.

2. The method for preparing an indium selenide / tin selenide binary heterojunction nanomaterial according to claim 1, characterized in that: The mass ratio of selenium powder I to polyvinylpyrrolidone is 1:1~20.

3. The method for preparing an indium selenide / tin selenide binary heterojunction nanomaterial according to claim 1 or 2, characterized in that: The volume ratio of hydrazine hydrate to water is 1:5~10.

4. The method for preparing an indium selenide / tin selenide binary heterojunction nanomaterial according to claim 1, characterized in that: The conditions for the solvothermal reaction are: temperature 160~220℃, time 12~28h.

5. An indium selenide / tin selenide binary heterojunction nanomaterial, characterized in that: It is prepared by the method described in any one of claims 1 to 4.

6. The application of the indium selenide / tin selenide binary heterojunction nanomaterial according to claim 5, characterized in that: It is applied to the catalytic degradation of organic pollutants and the catalytic reduction of inorganic pollutants.

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