A method for preparing high-purity bismuth selenide by regulating precursor concentration

Abstract

The application belongs to the technical field of two-dimensional semiconductor nanomaterials, and discloses a method for preparing high-purity bismuth selenide by regulating and controlling precursor concentration. The application realizes full reaction and precise matching of bismuth source and selenium source by precisely controlling the concentration of bismuth source in a bismuth precursor solution, the concentration of selenium source in a selenium precursor dispersion, and optimizing the molar ratio of bismuth and selenium, effectively avoids the generation of unreacted precursor residues and impurities, and the prepared bismuth selenide nanomaterial has extremely high purity, does not need an additional purification process, reduces the preparation cost, ensures excellent physicochemical properties of the material, and can meet the stringent requirements of photothermal, biomedical and other fields for high-purity bismuth selenide materials.

Description

Technical Field

[0001] This invention belongs to the field of two-dimensional semiconductor nanomaterials and relates to a method for preparing high-purity bismuth selenide by controlling the concentration of precursors. Background Technology

[0002] Bismuth selenide (Bi₂Se₃) is a V₂VI₃ type semiconductor material with a layered structure, exhibiting significant anisotropy and a band gap of approximately 0.3 eV. This material possesses excellent photoelectric properties, nonlinear optical characteristics, and efficient photothermal conversion capabilities, making it valuable for applications in thermoelectric devices, optoelectronic devices, infrared detection, photocatalysis, medical photothermal therapy, and solar-powered seawater desalination.

[0003] The solvothermal method, due to its low cost, simple operation, and ease of large-scale preparation, meets the core requirements of nanomaterial preparation and is the preferred synthesis process for Bi₂Se₃ nanomaterials. However, existing solvothermal synthesis technologies still face problems such as the use of high-risk reagents, low product purity, and harsh reaction conditions. For example, the literature (Materials Letters 2010, 493-496) reports that using bismuth nitrate and selenium powder in a molar ratio of 2:3 as raw materials, and using hydrazine hydrate as a solvent to dissolve bismuth nitrate before solvothermal reaction, but hydrazine hydrate has excessively strong reducing properties and high toxicity, posing significant safety hazards. This seriously restricts the large-scale production and practical application of Bi₂Se₃ nanomaterials. Therefore, developing a low-cost, high-purity solvothermal synthesis method for Bi₂Se₃ nanosheets and expanding its application in the field of solar-interface seawater desalination has become a key technical problem that urgently needs to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing high-purity bismuth selenide by controlling the concentration of precursors.

[0005] The technical solution of the present invention: A method for preparing high-purity bismuth selenide by controlling the precursor concentration includes the following steps: Step 1: Mix bismuth salt and alcohol in a preset ratio, place the mixture in a magnetic stirrer and stir, and heat the mixture in a water bath until completely dissolved to obtain a homogeneous and stable bismuth precursor solution. Step 2: Add selenium powder to the solvent according to the preset ratio, place the mixture in an ultrasonic device for ultrasonic treatment, and sonicate until the selenium powder is evenly dispersed to form a stable selenium precursor dispersion. Step 3: Mix the bismuth precursor solution and the selenium precursor dispersion, and carry out a solvothermal reaction; Step 4: After the reaction is completed, the reaction slurry is centrifuged, washed and dried in sequence to obtain black nanoparticles, which are bismuth selenide (Bi2Se3). Preferably, in step one, the bismuth salt is one or a mixture of two or more of bismuth nitrate pentahydrate, bismuth chloride, bismuth citrate, bismuth acetate, and bismuth sulfate.

[0006] Preferably, in step one, the alcohol is one or a mixture of two or more of methanol, ethanol, ethylene glycol, propylene glycol, butanediol, diethylene glycol, and neopentyl glycol.

[0007] Preferably, in step one, the concentration of the bismuth source in the bismuth precursor solution is 0.5~4 mol / L.

[0008] Preferably, in step two, the solvent is one or a mixture of two or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetonitrile, diethylene glycol, and sulfolane.

[0009] Preferably, in step two, the concentration of the selenium source in the selenium precursor dispersion is 8~20 g / L.

[0010] Preferably, in step three, the precursor solution and the selenium precursor dispersion are mixed at a bismuth to selenium molar ratio of 2:5 to 1:1. Preferably, in step three, the solvothermal reaction temperature is 160~200℃ and the time is 12~24 h; The bismuth selenide (Bi2Se3) nanomaterials prepared by the above method are very pure and have a two-dimensional sheet-like structure.

[0011] The present invention also provides the application of the above-mentioned bismuth selenide (Bi2Se3) nanomaterials in driving interfacial water evaporation, wherein the bismuth selenide (Bi2Se3) nanomaterials are used as photothermal materials in solar evaporators.

[0012] Specifically, a polyvinyl alcohol (PVA) solution is uniformly mixed with glutaraldehyde and bismuth selenide (Bi2Se3) nanomaterials to form a slurry. A foaming agent is then added and mechanically stirred to foam the mixture. A crosslinking initiator is added, and stirring continues until a foamy precursor is formed. After static crosslinking, a hydrogel foam is formed. Finally, a swelling treatment is performed to obtain the BSP photothermal composite hydrogel. Subsequently, a 1 cm diameter hole is made in the center of a polyethylene foam float and filled with absorbent cotton. The BSP photothermal composite hydrogel is placed on top of this hole, contacting the absorbent cotton. This ensures water supply while achieving physical isolation between the evaporator and the large volume of water, thus producing the BSP evaporator.

[0013] The beneficial effects of this invention are as follows: By precisely controlling the concentration of bismuth source in the bismuth precursor solution and the concentration of selenium source in the selenium precursor dispersion, and optimizing the molar ratio of bismuth to selenium, this invention achieves full reaction and precise matching of bismuth and selenium sources, effectively avoiding unreacted precursor residues and impurity phase formation. The resulting bismuth selenide (Bi2Se3) nanomaterials have extremely high purity, requiring no additional purification process, thus reducing preparation costs. At the same time, it ensures the excellent physicochemical properties of the material, which can meet the stringent requirements of high-purity bismuth selenide materials in fields such as photothermal and biomedicine. Attached Figure Description

[0014] Figure 1 This is a scanning electron microscope image of the Bi2Se3 nanomaterials prepared in Example 1.

[0015] Figure 2 The image shows the XRD pattern of the Bi2Se3 nanomaterial in Example 1.

[0016] Figure 3 Photographs of the slurry sediments obtained after the reaction of Example 1 and Comparative Examples 1-3 are shown. Among them, (a) the precipitate of Example 1 is almost free of impurities; (b) the precipitate of Comparative Example 1 contains white impurities with obvious pearly luster; (c) the precipitate of Comparative Example 2 has a more pronounced pearly luster of the white impurities; and (d) the precipitate of Comparative Example 3 contains a large number of white impurities with pearly luster.

[0017] Figure 4 The photothermal conversion capabilities of evaporators constructed from Bi₂Se₃ prepared in Example 1 and Comparative Example 4 (denoted as BSP1 and BSP2, respectively) were compared. (a) shows the photothermal conversion capability of BSP1 in a dry state under 1 solar irradiance (1 kW·m⁻¹). -2 (a) is the highest temperature that can be achieved under the same conditions; (b) is the highest temperature that BSP2 can achieve under the same conditions.

[0018] Figure 5 This is a comparison diagram of the water evaporation performance of the evaporators prepared in Example 1 and Comparative Example 5. Detailed Implementation

[0019] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0020] Example 1 2.4 mmol of bismuth chloride was weighed and placed in a reaction vessel, and 3 mL of ethylene glycol (EG) was added. The mixture was heated and stirred at 60 °C under magnetic stirring until the bismuth chloride was completely dissolved, obtaining a homogeneous and clear bismuth precursor solution. Separately, 3 mmol of selenium powder (Se) was added to 15 mL of N,N-dimethylformamide (DMF), and the mixture was sonicated until the selenium powder was uniformly dispersed, thus obtaining a stable selenium precursor dispersion. The bismuth precursor solution and the selenium precursor dispersion were thoroughly mixed, and then the mixture was transferred to a high-purity high-pressure reactor and sealed. The reaction was carried out at 170 °C for 18 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The resulting reaction slurry was centrifuged, washed three times with anhydrous ethanol, and then dried in a 60 °C oven for 6 h to obtain black nanoparticles.

[0021] X-ray diffraction characterization showed that the product's diffraction peaks were consistent with the standard card (JCPDS No. 33-0214), with no impurity peaks, indicating high phase purity. Figure 1 As shown; Scanning electron microscopy revealed that the product exhibited a two-dimensional sheet-like microstructure, such as... Figure 2 As shown; The slurry sediment after the reaction was completed contained only a very small amount of pearly white impurities, such as Figure 3 As shown in a; Example 2 1.2 mmol of bismuth chloride was weighed and placed in a reaction vessel, and 2.4 mL of ethylene glycol (EG) was added. The mixture was heated and stirred at 60 °C under magnetic stirring until the bismuth chloride was completely dissolved, obtaining a homogeneous and clear bismuth precursor solution. Separately, 3 mmol of selenium powder (Se) was added to 30 mL of N,N-dimethylformamide (DMF), and the mixture was sonicated until the selenium powder was uniformly dispersed, thus obtaining a stable selenium precursor dispersion. The bismuth precursor solution and the selenium precursor dispersion were thoroughly mixed, and then the mixture was transferred to a high-purity high-pressure reactor and sealed. The reaction was carried out at 160 °C for 12 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The resulting reaction slurry was centrifuged, washed three times with anhydrous ethanol, and then dried in a 60 °C oven for 6 h to obtain black nanoparticles.

[0022] This embodiment also yielded high-purity sheet-like Bi2Se3 nanoparticles.

[0023] Example 3 3 mmol of bismuth chloride was weighed and placed in a reaction vessel, and 0.75 mL of ethylene glycol (EG) was added. The mixture was heated and stirred at 60 °C under magnetic stirring until the bismuth chloride was completely dissolved, obtaining a homogeneous and clear bismuth precursor solution. Separately, 3 mmol of selenium powder (Se) was added to 12 mL of N,N-dimethylformamide (DMF), and the mixture was sonicated until the selenium powder was uniformly dispersed, thus obtaining a stable selenium precursor dispersion. The bismuth precursor solution and the selenium precursor dispersion were thoroughly mixed, and then the mixture was transferred to a high-purity high-pressure reactor and sealed. The reaction was carried out at 200 °C for 24 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The resulting reaction slurry was centrifuged, washed three times with anhydrous ethanol, and then dried in a 60 °C oven for 6 h to obtain black nanoparticles.

[0024] This embodiment also yielded high-purity sheet-like Bi2Se3 nanoparticles.

[0025] Comparative Example 1 2.4 mmol of bismuth chloride was weighed and placed in a reaction vessel, and 0.4 mL of ethylene glycol (EG) was added. The mixture was heated and stirred at 60 °C under magnetic stirring until the bismuth chloride was completely dissolved, resulting in a homogeneous and clear bismuth precursor solution. Separately, 3 mmol of selenium powder (Se) was added to 20 mL of N,N-dimethylformamide (DMF), and the mixture was sonicated until the selenium powder was uniformly dispersed, thus obtaining a stable selenium precursor dispersion. The bismuth precursor solution and the selenium precursor dispersion were thoroughly mixed, and then the mixture was transferred to a high-purity high-pressure reactor and sealed. The mixture was reacted at 170 °C for 18 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The resulting reaction slurry was centrifuged, washed three times with anhydrous ethanol, and then dried in a 60 °C oven for 6 h to obtain black nanoparticles with a small amount of white nanoparticles interspersed within them.

[0026] After the reaction, noticeable pearly white impurities appeared in the sediment of the slurry, such as... Figure 3 As shown in b.

[0027] Comparative Example 2 2.4 mmol of bismuth chloride was weighed and placed in a reaction vessel, and 7 mL of ethylene glycol (EG) was added. The mixture was heated and stirred at 60 °C under magnetic stirring until the bismuth chloride was completely dissolved, resulting in a homogeneous and clear bismuth precursor solution. Separately, 3 mmol of selenium powder (Se) was added to 20 mL of N,N-dimethylformamide (DMF), and the mixture was sonicated until the selenium powder was uniformly dispersed, thus obtaining a stable selenium precursor dispersion. The bismuth precursor solution and the selenium precursor dispersion were thoroughly mixed, and then the mixture was transferred to a high-purity high-pressure reactor and sealed. The mixture was reacted at 170 °C for 18 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The resulting reaction slurry was centrifuged, washed three times with anhydrous ethanol, and then dried in a 60 °C oven for 6 h to obtain black nanoparticles with a small amount of white nanoparticles interspersed within them.

[0028] After the reaction, more pronounced pearlescent white impurities appeared in the slurry sediment, such as... Figure 3 As shown in c.

[0029] Comparative Example 3 2.4 mmol of bismuth chloride was weighed and placed in a reaction vessel. 3 mL of ethylene glycol (EG) was added, and the mixture was heated and stirred at 60 °C under magnetic stirring until the bismuth chloride was completely dissolved, obtaining a homogeneous and clear bismuth precursor solution. Separately, 3 mmol of selenium powder (Se) was added to 7 mL of N,N-dimethylformamide (DMF), and the mixture was sonicated until the selenium powder was uniformly dispersed, obtaining a stable selenium precursor dispersion. The bismuth precursor solution and the selenium precursor dispersion were thoroughly mixed, and then the mixture was transferred to a high-purity high-pressure reactor and sealed. The mixture was reacted at 170 °C for 18 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The resulting reaction slurry was centrifuged, washed three times with anhydrous ethanol, and then dried in a 60 °C oven for 6 h to obtain a black powder containing a large number of white particles.

[0030] After the reaction, very obvious pearly white impurities appeared in the sediment of the slurry, such as... Figure 3 As shown in d.

[0031] Comparative Example 4 2.4 mmol of bismuth chloride was weighed and placed in a reaction vessel, and 3 mL of ethylene glycol (EG) was added. The mixture was heated and stirred at 60 °C under magnetic stirring until the bismuth chloride was completely dissolved, obtaining a homogeneous and clear bismuth precursor solution. Separately, 3 mmol of selenium powder (Se) was added to 40 mL of N,N-dimethylformamide (DMF), and the mixture was sonicated until the selenium powder was uniformly dispersed, thus obtaining a stable selenium precursor dispersion. The bismuth precursor solution and the selenium precursor dispersion were thoroughly mixed, and then the mixture was transferred to a high-purity high-pressure reactor and sealed. The reaction was carried out at 170 °C for 18 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The resulting reaction slurry was centrifuged, washed three times with anhydrous ethanol, and then dried in a 60 °C oven for 6 h to obtain black nanoparticles.

[0032] Although the product is pure Bi2Se3 nanoparticles, excessive nucleation leads to overly fine particles, dense defects, rapid carrier recombination, and poor photothermal conversion performance.

[0033] Application examples Using sheet-like Bi₂Se₃ nanoparticles prepared in Example 1 and Comparative Example 4 as photothermal materials, respectively, they were loaded onto PVA hydrogels under the same procedures and dosage conditions to prepare solar evaporation systems, named BSP1 and BSP2, respectively. Photothermal conversion and water evaporation experiments were conducted under the same test conditions, and the results are as follows: Figure 4 , Figure 5 As shown, BSP1 exhibits significantly better photothermal conversion capacity and evaporation rate than BSP2. This indicates that the sheet-like Bi2Se3 nanomaterials prepared using the method of this invention possess excellent evaporation performance in the field of solar-interface seawater desalination, and the preparation process is simple, demonstrating promising prospects for practical applications.

Claims

1. A method for preparing high-purity bismuth selenide by controlling the precursor concentration, characterized in that, Includes the following steps: Step 1: Mix bismuth salt and alcohol in a preset ratio, place the mixture in a magnetic stirrer and stir, and heat the mixture in a water bath until completely dissolved to obtain a homogeneous and stable bismuth precursor solution. Step 2: Add selenium powder to the solvent according to the preset ratio, place the mixture in an ultrasonic device for ultrasonic treatment, and sonicate until the selenium powder is evenly dispersed to form a stable selenium precursor dispersion. Step 3: Mix the bismuth precursor solution and the selenium precursor dispersion, and carry out a solvothermal reaction; Step 4: After the reaction is complete, the reaction slurry is centrifuged, washed and dried in sequence to obtain black nanoparticles, which are bismuth selenide.

2. The method for preparing high-purity bismuth selenide by controlling the precursor concentration according to claim 1, characterized in that, In step one, The bismuth salt is one or a mixture of two or more of bismuth nitrate pentahydrate, bismuth chloride, bismuth citrate, bismuth acetate, and bismuth sulfate; The alcohols are one or a mixture of two or more of methanol, ethanol, ethylene glycol, propylene glycol, butanediol, diethylene glycol, and neopentyl glycol; The concentration of the bismuth source in the bismuth precursor solution is 0.5~4 mol / L.

3. The method for preparing high-purity bismuth selenide by controlling the precursor concentration according to claim 1, characterized in that, In step two, The solvent is one or a mixture of two or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetonitrile, diethylene glycol, and sulfolane. The concentration of the selenium source in the selenium precursor dispersion is 8~20 g / L.

4. The method for preparing high-purity bismuth selenide by controlling the precursor concentration according to claim 1, characterized in that, In step three, The precursor solution and the selenium precursor dispersion were mixed at a bismuth to selenium molar ratio of 2:5 to 1:

1. The solvothermal reaction temperature is 160~200℃, and the time is 12~24 h.

5. Bismuth selenide obtained by any one of the preparation methods according to claims 1-4.

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