A copper-doped tin selenide thermoelectric catalyst, and a preparation method and application thereof

Abstract

The application discloses a doped copper-selenium tin thermoelectric catalyst and a preparation method and application thereof, and belongs to the technical field of environment-friendly thermoelectric materials. ‑ A tetravalent selenium source is taken into a solvent I, stirred uniformly to obtain a solution I; a divalent tin source, an OH ‑ source, a divalent copper source are sequentially added into a solvent II, continuously stirred during the adding process, stirred uniformly to obtain a solution II, the solution I and the solution II are mixed, a reducing agent is added after uniform stirring, and a hydrothermal reaction is carried out; after the reaction is completed, the remaining solid is obtained by removing the liquid, and the obtained solid is cleaned and dried to obtain the doped copper-selenium tin thermoelectric catalyst. The application uses low-content copper-doped selenium tin nanomaterial as a thermoelectric catalyst to treat organic pollutants in wastewater, the preparation process of the nanomaterial is simple, safety is good, cost is low, raw materials are widely sourced, the nanomaterial has good thermoelectric performance and catalytic performance, and can be applied to the field of environmental protection.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of environmental protection thermoelectric materials, and specifically relates to a copper-doped stannum selenide thermoelectric catalyst and a preparation method and application thereof. BACKGROUND

[0002] Methylene blue is one of the typical organic pollutants in printing and dyeing wastewater, and its degradation and decolorization is one of the important research contents of printing and dyeing wastewater treatment.

[0003] Stannum selenide is an excellent thermoelectric material, which has a layered and highly anisotropic crystal structure, ultra-low lattice thermal conductivity, ultra-high power factor and high thermoelectric figure of merit, and is environmentally friendly, low toxicity, rich in reserves and low in price, so it is considered to be a feasible solution to energy and environmental problems. Doping process is an effective method to improve the thermoelectric performance of stannum selenide, however, due to the low solubility and efficiency of various doping, there is a mutual dependence between various thermoelectric parameters, and the chemical doping of stannum selenide is still a challenge, and the selection of appropriate doping is a key factor to improve the thermoelectric performance.

[0004] CN114203894A discloses a ytterbium-doped stannum selenide thermoelectric material and a preparation method thereof. Ytterbium-doped stannum selenide powder material is synthesized by a solvothermal method, and discharge plasma sintering technology is used to sinter the sample into a block in the pressing process by using high current heating. The plasma generated by the pulse current and the pressure in the sintering process are beneficial to reduce the sintering temperature of the powder, and the characteristics of low voltage and high current can make the powder sintered quickly and densely. The method is simple, time-consuming is short, and a small amount of rare earth element ytterbium is doped to improve the power factor of the material by 60% at 823K, and the thermoelectric figure of merit zT reaches 1.1, which significantly improves the thermoelectric performance of stannum selenide material. However, the method needs to use discharge plasma sintering technology, which is complex to operate, and the rare earth element ytterbium is expensive, so the cost is high, which is not suitable for mass production.

[0005] At present, there is no detailed research on the preparation method of copper-doped stannum selenide, therefore, it is necessary to develop a simple and efficient, low-cost preparation method of copper-doped stannum selenide thermoelectric catalyst, and to use the copper-doped stannum selenide thermoelectric catalyst in the field of environmental protection, and to explore its effect as a thermoelectric catalyst to degrade methylene blue wastewater. SUMMARY

[0006] In view of the technical problems existing in the prior art, the present application provides a doped copper tin selenide thermoelectric catalyst and a preparation method and application thereof. Doping copper in tin selenide crystals can effectively play a lattice scattering role, improve the carrier concentration in the tin selenide crystals, reduce the crystal symmetry of the Pnma phase, improve the electrical properties of the material, and make it obtain better electrical transport performance. Moreover, while optimizing the thermoelectric performance of tin selenide, it can also effectively prevent the oxidation of tin selenide. The synthesis method is simple, efficient and low in cost, can be used for degrading methylene blue, and is environmentally friendly.

[0007] The technical scheme adopted by the present application is:

[0008] A preparation method of a doped copper tin selenide thermoelectric catalyst, comprising the following steps:

[0009] (1) Take a tetravalent selenium source and add it to solvent one, stir uniformly to obtain solution one; take a divalent tin source, OH - alkali source and divalent copper source and add them to solvent two in sequence, continuously stir during the adding process, stir uniformly to obtain solution two, mix solution one and solution two, stir uniformly, then add a reducing agent, and perform hydrothermal reaction;

[0010] (2) After the reaction is completed, remove the liquid and take the remaining solid, and clean and dry the obtained solid to obtain the doped copper tin selenide thermoelectric catalyst;

[0011] The molar ratio of the selenium source, the tin source, the copper source, OH - alkali source is 1.2:1:(0.0005-0.003):(25-50).

[0012] Further, the selenium source is selenium dioxide, the tin source is tin dichloride, the copper source is copper chloride, the solvent one is ethylene glycol, the solvent two is deionized water, the reducing agent is hydrazine hydrate, and the OH - alkali source is sodium hydroxide.

[0013] Further, the hydrothermal reaction condition in step (1) is that the temperature is 180-200 DEG C, and the time is 12-36 h.

[0014] Further, in step (2), the liquid is removed and the remaining solid is taken by using the method of centrifugation, centrifugation is performed at 8000-12000 r / min for at least 5 min, the obtained solid is cleaned by centrifugation, and then dried; the drying method is vacuum drying, the drying temperature is not more than 60 DEG C, and the drying time is 12-16 h.

[0015] Further, in step (2), the liquid is removed and the remaining solid is taken by using the method of suction filtration, the obtained solid is cleaned by suction filtration, and then dried; the drying method is vacuum drying, the drying temperature is not more than 60 DEG C, and the drying time is 12-16 h.

[0016] Further, the cleaning uses anhydrous ethanol and deionized water, and is cleaned twice respectively.

[0017] The application also provides a doped copper tin selenide thermoelectric catalyst prepared by the method.

[0018] Further, the doped copper tin selenide thermoelectric catalyst has a rectangular flake structure, and a crystal spacing of 0.31 nm.

[0019] The application also provides an application of the doped copper tin selenide thermoelectric catalyst prepared by the method in degradation of methylene blue.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] (1) SnCl2, SeO2, NaOH, CuCl2, hydrazine hydrate and deionized water are mixed into a precursor solution, and then the precursor solution is placed in a hydrothermal reaction kettle to perform hydrothermal reaction, so as to synthesize a low-content doped copper tin selenide nanomaterial, which is used as a thermoelectric catalyst to treat organic pollutants in wastewater, and has the advantages of simple preparation process, good safety, low cost, wide raw material sources, suitability for large-scale production, good thermoelectric performance and catalytic performance, and application in the environmental protection field.

[0022] (2) The copper doped tin selenide can replace the intrinsic defects (Sn vacancies) originally existing in the tin selenide, after doping a low content of copper, the carrier concentration in the tin selenide crystal is increased, the electrical performance is enhanced, and the degradation effect on methylene blue is enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a scanning electron microscope (SEM) image of tin selenide in the comparative example of the application;

[0024] Figure 2 It is a scanning electron microscope (SEM) image of 0.25% copper doped tin selenide in example 5 of the application;

[0025] Figure 3 It is an X-ray diffraction (XRD) spectrum of tin selenide in the comparative example of the application and 0.25% copper doped tin selenide in example 5 of the application;

[0026] Figure 4 It is a transmission electron microscope (TEM) image of tin selenide in the comparative example of the application;

[0027] Figure 5 It is a transmission electron microscope (TEM) image of 0.25% copper doped tin selenide in example 5 of the application;

[0028] Figure 6 It is a degradation effect diagram of methylene blue by tin selenide without copper doping and tin selenide with copper doping. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some examples of the present application, rather than all other embodiments of the present application. All other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of the present application.

[0030] Preparation method of copper-doped SnSe and application in degradation of methylene blue

[0031] 1. (1) About 50 mL of ethylene glycol solution was measured by a measuring cylinder and added into a polytetrafluoroethylene reaction kettle, a stirring magnet was put in, and stirring was started;

[0032] (2) 0.666 g of selenium dioxide powder was weighed and slowly added into the reaction kettle (to prevent agglomeration into blocks), and after sufficient stirring, the solution was yellowish and had no obvious impurities;

[0033] (3) 0.95 g of tin dichloride powder was weighed and slowly added into a beaker, 100 mL of deionized water was added, and after sufficient stirring, the solution was white and turbid; 5 g of sodium hydroxide was slowly added into the solution, and after stirring, the solution was transparent and had no obvious impurities;

[0034] (4) The liquid in the beaker was slowly poured into the reaction kettle, and after sufficient stirring, 12.5 mL of hydrazine hydrate was added;

[0035] (5) The stirred mixed solution was put into the outer sleeve of the reaction kettle steel bottle, tightly screwed, and then put into an oven preheated in advance, heated at 180℃ for 12 h;

[0036] (6) After cooling to room temperature, the reaction kettle was removed, the solution was centrifuged at a centrifugal speed of 8000 r / min for 10 min in a centrifuge, the upper solution was sucked out, the precipitate was washed twice with anhydrous ethanol and twice with deionized water, and the finally obtained grayish-brown solid was dried in a vacuum drying box, the temperature should not exceed 60℃, the drying time was 12 h, and the vacuum pump was started every 20 min during the drying to extract the product. The scanning electron microscope image of the product is shown in Figure 1 , the transmission electron microscope image is shown in Figure 4 , and the X-ray diffraction pattern is shown in Figure 3 .

[0037] Figure 1 The scanning electron microscope image of SnSe of Figure 4 embodies the layer structure of the SnSe after copper doping. The electrical properties of the copper-doped SnSe are enhanced, which is conducive to enhancing the degradation effect on methylene blue.

[0038] 2. The undoped copper tin selenide was used for methylene blue degradation testing: A 45 mg / L methylene blue solution was prepared. 10 mL of the methylene blue solution was weighed and placed in a glass bottle. 10 mg of the synthesized doped copper tin selenide was added, and the bottle was placed in a 75°C water bath with continuous stirring. Every 15 minutes, 300 μL was taken out and its UV absorption spectrum was measured. The degree of degradation was determined by the change in the peak value of the UV absorption spectrum. (See attached table). Figure 6 .

[0039] Example 1 Preparation method and application of copper-doped 0.05% tin selenide 1. (1) Use a graduated cylinder to measure about 50 mL of ethylene glycol solution and add it to the polytetrafluoroethylene reaction vessel. Place a stirring magnet in the vessel and start stirring.

[0040] (2) Weigh 0.666g of selenium dioxide powder and slowly add it to the reaction vessel (to prevent agglomeration). After stirring thoroughly, the solution turns slightly yellow and has no obvious impurities.

[0041] (3) Weigh 0.95g of tin dichloride powder and slowly add it to a beaker. Add 100mL of deionized water and stir thoroughly. The solution is white and turbid. Slowly add 5g of sodium hydroxide and stir. The solution is transparent and free of obvious impurities.

[0042] (4) After stirring, add 0.33 mg of copper chloride powder (the molar amount of copper chloride doping is 0.05% of the molar amount of tin dichloride) to the solution and continue stirring;

[0043] (5) Slowly pour the liquid in the beaker into the reaction vessel, stir thoroughly, and then add 12.5 mL of hydrazine hydrate;

[0044] (6) Place the stirred mixture into the outer sleeve of the reaction vessel cylinder, tighten it, and then place it in a preheated oven and heat at 180°C for 12 hours.

[0045] (7) After cooling to room temperature, remove the reaction vessel and centrifuge the solution in a centrifuge at a speed of 8000 r / min for 10 min. Remove the upper layer of solution, wash the precipitate twice with anhydrous ethanol and then twice with deionized water. Place the final grayish-brown solid in a vacuum drying oven for drying. The temperature should not exceed 60℃ and the drying time is 12 h. During this period, turn on the vacuum pump every 20 min to evacuate the product.

[0046] 2. Application of copper-doped tin selenide thermoelectric catalyst in the degradation of methylene blue: Prepare a 45 mg / L methylene blue solution. Weigh 10 mL of the methylene blue solution and place it in a glass bottle. Add 10 mg of the synthesized copper-doped tin selenide solution to the bottle. Place the bottle in a 75°C water bath and stir continuously. Take 300 μL every 15 minutes to measure its UV absorption spectrum. The degree of degradation is judged by the change in the peak value of the UV absorption spectrum. See [link to relevant documentation]. Figure 6 .

[0047] Example 2 Preparation of copper-doped 0.1% tin selenide and its application

[0048] 1. The preparation method of copper-doped 0.1% tin selenide is the same as that of Example 1, except that 0.68 mg of copper chloride powder is added in step (4).

[0049] 2. The application method in the degradation of methylene blue is the same as that of Example 1, and the degradation effect is shown in Figure 6 .

[0050] Example 3 Preparation of copper-doped 0.15% tin selenide and its application

[0051] 1. The preparation method of copper-doped 0.15% tin selenide is the same as that of Example 1, except that 1 mg of copper chloride powder is added in step (4).

[0052] 2. The application method in the degradation of methylene blue is the same as that of Example 1, and the degradation effect is shown in Figure 6 .

[0053] Example 4 Preparation of copper-doped 0.2% tin selenide and its application

[0054] 1. The preparation method of copper-doped 0.2% tin selenide is the same as that of Example 1, except that 1.35 mg of copper chloride powder is added in step (4).

[0055] 2. The application method in the degradation of methylene blue is the same as that of Example 1, and the degradation effect is shown in Figure 6 .

[0056] Example 5 Preparation of copper-doped 0.25% tin selenide and its application 1. The preparation method of copper-doped 0.25% tin selenide is the same as that of Example 1, except that 1.68 mg of copper chloride powder is added in step (4). The scanning electron microscope image of the product is shown in Figure 2 , the transmission electron microscope image is shown in Figure 5 , and the X-ray diffraction pattern is shown in Figure 3 .

[0057] Figure 2 The scanning electron microscope image of Figure 5 and the transmission electron microscope image of indicate that after copper doping, tin selenide changes from irregular flake structure to more regular rectangular flake structure, and the thickness increases. The electrical properties of copper-doped tin selenide are enhanced, which is beneficial to enhancing the degradation effect on methylene blue.

[0058] Figure 3XRD patterns of the two samples show that the diffraction peaks of both samples can be uniquely marked as SnSe with an orthogonal structure and Pnma space group, the XRD of the doped sample is slightly shifted to the left, and the slight right shift of the peak also indicates that there are tin vacancies in the SnSe structure, and the half peak width becomes larger, indicating that the crystal face spacing becomes larger after doping. The electrical properties of copper-doped tin selenide are enhanced, which is beneficial to enhance the degradation effect of methylene blue. Figure 6 .

[0059] Example 6 Preparation method and application of copper-doped 0.3% tin selenide

[0060] 1. The preparation method of copper-doped 0.3% tin selenide is the same as that of Example 1, the difference is that 2.03 mg of copper chloride powder is added in step (4).

[0061] 2. The application method in the degradation of methylene blue is the same as that of Example 1, and the degradation effect is shown in Figure 6 .

[0062] Figure 6 It is shown that, compared with undoped copper selenide, copper-doped selenide has obvious degradation effect on methylene blue, and as the doping amount increases, the degradation effect gradually becomes better, and when the doping amount is 0.25%, the degradation effect on methylene blue is the most obvious.

[0063] In the above preparation method, in step (7), if the product is more, an extraction filtration device can be used to extract the solid, and the extraction filtration device can be used to extract the solid. After washing twice with ethanol and twice with deionized water, the finally obtained gray-brown solid is placed in a vacuum drying box for drying. The extraction filtration method is more convenient and time-saving than the centrifugal method.

[0064] It should be noted that the selenium source can also be sodium selenate, the copper source can also be copper sulfate, and the alkali source can also be potassium hydroxide; in the reaction system, ethylene glycol as a solvent can fully promote the ion exchange reaction between substances in the solution; sodium hydroxide as a pH balancing agent, in the case of no addition or insufficient addition, tin dichloride is partially hydrolyzed to Sn 2+ SnSe2 is generated in the reaction, resulting in poor product crystallization; hydrazine hydrate as a reducing agent; the copper doping of the final product in the tin selenide lattice.

[0065] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a copper-doped tin selenide thermoelectric catalyst, characterized in that, Includes the following steps: (1) Selenium dioxide was added to ethylene glycol and stirred until homogeneous to obtain solution one; tin dichloride, sodium hydroxide and copper chloride were added to deionized water in sequence and stirred continuously during the addition process until homogeneous to obtain solution two; solution one and solution two were mixed and stirred until homogeneous, and then hydrazine hydrate was added to carry out hydrothermal reaction. The hydrothermal reaction conditions were a temperature of 180 ℃-200 ℃ and a time of 12h-36h. (2) After the reaction is complete, remove the liquid and take the remaining solid. Then, wash and dry the obtained solid to obtain the copper-doped tin selenide thermoelectric catalyst. The molar ratio of selenium dioxide, tin dichloride, copper chloride, and sodium hydroxide is 1.2:1:(0.0005-0.003):(25-50). Remove the liquid and collect the remaining solid by centrifugation at 8000 r / min-12000 r / min for at least 5 min. After centrifugation and washing, the solid is dried. The drying method is vacuum drying, the drying temperature does not exceed 60 ℃, and the drying time is 12 h-16 h.

2. The method for preparing a copper-doped tin selenide thermoelectric catalyst according to claim 1, characterized in that, The cleaning process involved two separate cleaning sessions using anhydrous ethanol and deionized water.

3. The copper-doped tin selenide thermoelectric catalyst prepared by the method according to any one of claims 1-2, characterized in that, The doped copper tin selenide thermoelectric catalyst has a rectangular sheet structure with a crystal plane spacing of 0.31 nm.

4. The application of the copper-doped tin selenide thermoelectric catalyst prepared by the preparation method according to claim 1 in the degradation of methylene blue.

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