A method for preparing AgSbTe2 nanomaterials by a solution method

Abstract

The present invention discloses a method for preparing AgSbTe2 nanomaterials by a solution method, which comprises the following steps: respectively adding cation solutions of Ag and Sb molecular ligands into an oleylamine solution that has been preheated and vacuum degassed, and rapidly heating to a specific temperature under argon protection. At this time, injecting a Te source precursor into the above reaction solution containing cations Ag and Sb, keeping warm for a certain time, and after completion, cooling the reaction solution to room temperature, centrifuging and washing to prepare AgSbTe2 nanocrystals. The preparation method of the present invention has simple process, low energy consumption and high yield, and is suitable for the large-scale and rapid synthesis of AgSbTe2-based nanomaterials.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-material preparation, and particularly to a method for preparing AgSbTe2 nano-materials by a solution method. Background Art

[0002] As a type of functional material, thermoelectric materials can directly convert temperature difference into electric energy or generate temperature difference for refrigeration by using electric energy, and are widely used in energy recovery, refrigeration, sensing and other fields. These materials achieve direct energy conversion through the thermoelectric effect, and the core performance index is the thermoelectric figure of merit (zT value, zT = σS2T / κ), which is a key index to measure the comprehensive performance of materials and reflects the relationship between the electrical conductivity (σ), Seebeck coefficient (S) and thermal conductivity (κ) of materials (where T is the absolute temperature). With the increasingly prominent environmental problems and the continuous growth of energy demand, the development and optimization of high-performance thermoelectric materials, especially those that can work effectively at room temperature or medium temperature, have become an important research direction in materials science. AgSbTe2 is a medium-temperature thermoelectric material, and its relatively high thermoelectric figure of merit zT and good performance stability have attracted extensive attention from researchers. This material particularly exhibits high thermoelectric conversion efficiency in the medium-temperature region and becomes an ideal choice for thermoelectric power generation and refrigeration applications. The crystal structure of AgSbTe2 is a face-centered cubic structure, which helps to optimize its electron transport performance while maintaining a relatively low thermal conductivity κ, which is a key factor for improving thermoelectric performance. In addition, its application potential and optimization space in the field of thermoelectric materials still need to be further explored and developed, indicating a great application prospect of AgSbTe2 in the field of energy conversion materials.

[0003] Traditionally, the synthesis of AgSbTe2 mainly relies on solid-state reaction and high-temperature melting method, especially vacuum melting method. Although these methods can achieve the preparation of AgSbTe2 to a certain extent, they face various challenges. In order to prevent the vacuum quartz tube from cracking due to too rapid temperature change, the melting method requires an extremely slow heating and cooling rate (about 0.3 - 0.4 K·min -1 ), and also requires an extremely high temperature above the melting point of its raw materials and maintaining for a long time. In addition, in order to promote the formation of the main phase of AgSbTe2, this method also requires long-term low-temperature annealing, and even needs to last for several days. However, even with this slow and time-consuming process, the generation of impurity phases such as Ag2Te and Sb2Te3 cannot be avoided, and these impurity phases will significantly affect the thermoelectric transport performance of AgSbTe2 materials.

[0004] Due to the fact that the size of nanostructures is close to the mean free path of phonons, the thermal conductivity κ can be effectively further reduced by scattering phonons, thereby enhancing the thermoelectric figure of merit zT of the material. Therefore, in order to prepare AgSbTe2 nanostructured materials, some traditional preparation strategies other than vacuum melting method have been adopted, such as chemical vapor transport method, sonochemical preparation method and solid-state reaction method. Although they have their unique advantages, they generally have problems such as long preparation time, high cost, cumbersome process and the need for high-temperature annealing. So far, no effective strategy has been found to directly prepare AgSbTe2 nanomaterials by large-scale synthesis through solution method. Typical liquid-phase synthesis mainly uses hydrothermal / solvothermal method with a high-pressure reaction kettle as the reaction vessel, which can prepare nanoscale composite materials, but its large-scale preparation is severely limited, reducing the economy of practical applications. Therefore, developing a new method that can achieve large-scale preparation at low temperature and precisely control the chemical composition and microstructure is not only of great academic value, but also crucial for promoting the practical application of thermoelectric materials. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing AgSbTe2 nanomaterials by solution method. The preparation method is simple, the synthesis conditions are mild and the energy consumption is low. It can achieve large-scale, rapid and precise synthesis of AgSbTe2 nanomaterials with intrinsic low thermal conductivity, and has good practical application value.

[0006] In one aspect of the present invention, the present invention proposes a method for preparing AgSbTe2 nanomaterials by solution method. According to an embodiment of the present invention, the method includes the following steps:

[0007] The molecular ligand solutions of Ag and Sb are respectively added to the preheated and vacuum degassed oleylamine solution, and rapidly heated to a specific temperature under argon protection to obtain a cation solution. The Te source precursor is injected into the above reacted cation solution, kept warm for a certain time, and after the reaction, the reaction solution is cooled to room temperature, centrifuged and washed to prepare AgSbTe2 nanocrystals.

[0008] In addition, according to a method for preparing AgSbTe2 nanomaterials by solution method of the above embodiment of the present invention, the following additional technical features may also be provided:

[0009] In some embodiments of the present invention, the method specifically includes the following steps:

[0010] (1) Preparation of cation and anion precursors

[0011] At room temperature, Te grains are dissolved in trioctylphosphine in a glove box and stirred to prepare a Te source precursor;

[0012] At room temperature, under an argon atmosphere, Ag2O and Sb2O3 were respectively added to a mixed solution of oleylamine and ethanethiol with a certain volume ratio, and stirred to prepare a molecular ligand solution of Ag and Sb, which was the cationic precursor;

[0013] (2) Preparation of AgSbTe2 nanomaterials by a liquid-phase method

[0014] After evacuating and degassing oleylamine under certain temperature conditions for a certain time, argon was introduced. The cationic Ag and Sb molecular ligand solutions were respectively injected into the oleylamine solvent according to a molar ratio of 1:(0.98 - 1.02). Subsequently, the temperature was rapidly raised to make the solution change from a turbid light brown to a yellow transparent, and then the Te source precursor was added for reaction. After the reaction, centrifugation and washing were carried out, followed by vacuum drying to obtain AgSbTe2 nanomaterials.

[0015] In some embodiments of the present invention, in the step (1), the concentration of the Te source precursor is 1.0 mol·L -1 , and the stirring time of Te particles and tri-n-octylphosphine is 3 - 5 days.

[0016] In some embodiments of the present invention, in the step (1), the volume ratio of oleylamine to ethanethiol is (3 - 4):1, and the stirring time is 6 - 12 h.

[0017] In some embodiments of the present invention, in the step (2), under the temperature condition of 100 - 130 °C, the evacuation and degassing time of oleylamine is not less than 30 min.

[0018] In some embodiments of the present invention, in the step (2), the molar ratio of Ag, Sb and Te is 1:(0.98 - 1.02):(2 - 2.05).

[0019] In some embodiments of the present invention, in the step (2), the reaction temperature is 170 - 190 °C, the reaction time is 50 - 70 min, and the washing is carried out by centrifugal washing with n-hexane and absolute ethanol for 2 - 4 times.

[0020] In some embodiments of the present invention, in the step (2), the centrifugation speed is 7000 - 9000 rpm, and the time is 5 - 10 min each time.

[0021] In some embodiments of the present invention, in the step (2), the drying is carried out by vacuum drying, the drying time is 4 - 8 hours, and the drying temperature is 60 - 80 °C.

[0022] On the other hand, the present invention provides an AgSbTe2 nanomaterial prepared by the method for preparing an AgSbTe2 nanomaterial according to the solution method described above. According to the embodiments of the present invention, the AgSbTe2 nanomaterial has an NaCl cubic rock-salt structure.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The present invention mainly focuses on the controllable morphology and size, large-scale and low-cost solution method for preparing AgSbTe2 nanomaterials. Compared with the traditional solid-phase vacuum melting method, the method of the present invention effectively solves the problem of Ag2Te and Sb2Te3 impurity phases that are difficult to eliminate during the melting process, and avoids the limitations such as uncontrollable impurity phases, long cycle and high energy consumption.

[0025] (2) Existing chemical methods such as chemical vapor transport method and ultrasonic chemical preparation method can synthesize AgSbTe2, but the cost is high and the yield is limited to the milligram level, and usually requires cumbersome post-annealing treatment to obtain the main phase. It has been reported that expensive and extremely flammable lithium bis(trimethylsilyl)amide (LiN(SiMe3)2) in air is used as a reducing agent for the synthesis of microgram-level AgSbTe2 pure phase, but this greatly limits its practical application. The present invention uses relatively cheap oxides Ag2O and Sb2O3 as raw materials to prepare Ag and Sb molecular ligands as cation precursors, and then reacts with Te source precursors according to a molar ratio. Through a unique low-temperature rapid synthesis strategy, AgSbTe2 nanomaterials can be prepared on a large scale.

[0026] (3) The present invention not only significantly reduces the preparation cycle and cost, but also effectively avoids the inevitable generation of impurity phases during the cooling process in solid-phase synthesis. Compared with the traditional "top-down" solid-phase melting method, the low-temperature synthesis strategy of the present invention can more precisely control the interface morphology and size of the material, demonstrating the uniqueness and superiority of its technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the X-ray diffraction pattern (XRD) of the AgSbTe2 nanomaterial prepared in Example 1 of the present invention;

[0028] Figure 2 a) and b) are respectively the scanning electron microscope SEM images of the AgSbTe2 nanomaterial powder prepared in Example 1 of the present invention at different magnifications, wherein, a) ×20.0K, b) ×30.0K;

[0029] Figure 3 It is the transmission electron microscope TEM image of the AgSbTe2 nanomaterial prepared in Example 1 of the present invention, wherein Figure b) is the enlarged view of the area in the white frame in Figure a);

[0030] Figure 4Scanning transmission electron microscopy (STEM) images of the AgSbTe2 nanomaterials prepared in Example 1 of the present invention and elemental distribution maps of the corresponding nanoparticles. a) High-angle annular dark-field (HAADF) image of AgSbTe2 nanoparticles, b) Ag. The table in the figure represents energy-dispersive X-ray spectroscopy (EDX) analysis in scanning transmission electron microscopy, i.e., the atomic percentages of the three elements Ag, Sb, and Te, c) Sb, d) Te;

[0031] Figure 5 Scanning transmission electron microscopy (STEM) images of the AgSbTe2 nanomaterials prepared in Example 1 of the present invention and elemental distribution maps of the corresponding nanorods. a) High-angle annular dark-field (HAADF) image of AgSbTe2 nanorods, b) Ag. The table in the figure represents energy-dispersive X-ray spectroscopy (EDX) analysis in scanning transmission electron microscopy, i.e., the atomic percentages of the three elements Ag, Sb, and Te, c) Sb, d) Te;

[0032] Figure 6 X-ray diffraction patterns (XRD) of the AgSbTe2 nanomaterials in Comparative Examples 1-4 and Example 1 of the present invention. Detailed implementation manners

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] Example 1

[0035] A method for preparing AgSbTe2 nanomaterials by a solution method, comprising the following steps:

[0036] (1) Preparation of cationic and anionic precursors

[0037] a. Large-scale preparation of anionic Te precursor: At room temperature, place 50 mmol of Te grains in a 50 mL glass container of tri-n-octylphosphine (TOP) in a glove box, and continuously stir magnetically for 5 days until completely dissolved. Finally, the solution becomes a bright yellow clear solution, and a Te source precursor (Te-TOP) stock solution with a concentration of 1.0 mol·L -1 is finally prepared.

[0038] b. Preparation of cationic precursors: First, 20 mL of oleylamine was degassed under vacuum at 120 °C for 60 min to remove low-boiling substances therein, and then argon was introduced. Second, in a glass bottle filled with argon, 2.0 mmol of Ag2O and Sb2O3 powders were weighed respectively and added into a mixed solution of 8 mL of degassed oleylamine and 2 mL of ethanethiol. The volume ratio of oleylamine to ethanethiol was 4:1. Magnetic stirring was carried out at room temperature for 12 h until it was completely clear and transparent. Finally, a molecular ligand solution of Ag and Sb with a concentration of 0.4 mol·L -1 was prepared.

[0039] (2) Preparation of AgSbTe2 nanomaterials by liquid-phase method

[0040] c. First, 70 mL of oleylamine was degassed under vacuum at 120 °C for 60 min to remove low-boiling substances therein, and then argon was introduced. Subsequently, the prepared molecular ligand solution of cationic Ag and Sb with a concentration of 0.4 mol·L -1 was injected into the oleylamine solvent at a molar ratio of 1:1 (both volumes were 10 mL). The temperature was rapidly increased under argon protection. During this process, the solution changed from turbid light brown to yellow transparent solution at about 170 °C. When the temperature reached 180 °C, 8 mL of 1.0 mol·L -1 Te source precursor Te-TOP prepared in step (1a) was injected into the cationic solution of Ag and Sb according to the molar ratio of Ag, Sb, and Te of 1:1:2. The reaction time was 60 min at 180 °C, and after that, it was cooled to room temperature in a water bath.

[0041] d. The solution after the reaction was centrifuged and washed with n-hexane as a dispersant and absolute ethanol as a precipitant. The volume ratio of n-hexane to absolute ethanol was 1:1, and it was centrifuged and washed 3 times at a rotation speed of 9000 rpm for 5 min each time. Finally, the obtained AgSbTe2 nanoparticles were transferred to a vacuum drying oven and dried at 60 °C for 6 h. Eventually, about 1.7 g of AgSbTe2 nanomaterial powder could be obtained, and the yield was close to 90% of the theoretical yield.

[0042] As Figure 1 shown, the XRD peaks of the AgSbTe2 nanomaterials prepared in Example 1 completely corresponded to the diffraction peaks of the standard card (PDF#00-015-0540) of the AgSbTe2 material, which proved that the liquid-phase method adopted in the present invention successfully synthesized pure-phase AgSbTe2. In addition, the samples synthesized in this patent had no obvious impurity phases, showing significant advantages in its composition control.

[0043] As Figure 2As shown, the material synthesized by the liquid-phase method adopted in this embodiment has a morphology of nanoparticles and nanorods. The size of the nanorods is several tens of nanometers in width and 1 - 2 micrometers in length, and the nanoparticles are about several tens to several hundreds of nanometers.

[0044] As Figure 3 shown, it can be observed from the two TEM characterizations that the morphology and size of the prepared AgSbTe2 nanomaterial are consistent with Figure 2 the characterization results of the scanning electron microscope in

[0045] As Figure 4 shown, the energy-dispersive X-ray spectroscopy (EDS) results of the scanning transmission electron microscope show that: for the three elements of Ag, Sb, and Te, except for a slightly enriched Ag in a small area, the element distribution is uniform in other large areas, and the total atomic percentage is close to the stoichiometric ratio of 1:1:2.

[0046] As Figure 5 shown, the energy-dispersive X-ray spectroscopy (EDS) results of the scanning transmission electron microscope show that: for the three elements of Ag, Sb, and Te, the distribution is uniform on the surface of the nanorods, and the content of Ag inside the nanorods is relatively high, and the total atomic percentage is close to the stoichiometric ratio of 1:1:2.

[0047] Example 2

[0048] A method for preparing AgSbTe2 nanomaterial by solution method, comprising the following steps:

[0049] (1) Preparation of cationic and anionic precursors

[0050] a. Large-scale preparation of anionic Te precursor: At room temperature, place 50 mmol of Te grains in a 50 mL glass container of tri-n-octylphosphine (TOP) in a glove box, and continuously stir magnetically for 5 days until completely dissolved. Finally, the solution becomes a bright yellow clear solution, and a Te source precursor (Te-TOP) stock solution with a concentration of 1.0 mol·L -1 is finally prepared.

[0051] b. First, evacuate and degas 40 mL of oleylamine at 120 °C for 60 min to remove the low-boiling substances therein, and then introduce argon. Secondly, in a glass bottle filled with argon, weigh 4.0 mmol of Ag2O and Sb2O3 powders respectively, and add them to a mixed solution of 16 mL of degassed oleylamine and 4 mL of ethanethiol. The volume ratio of oleylamine to ethanethiol is 4:1, and stir magnetically at room temperature for 12 h until completely clear and transparent. Finally, prepare a molecular ligand solution of Ag and Sb with a concentration of 0.4 mol·L -1

[0052] (2) Large-scale preparation of AgSbTe2 nanomaterial by liquid-phase method ​

[0053] c. First, 140 mL of oleylamine was degassed under vacuum at 120 °C for 60 min to remove low-boiling substances therein, and then argon was introduced. Subsequently, the molecular ligand solution of 0.4 mol·L -1 cationic Ag and Sb was injected into the oleylamine at a molar ratio of 1:1 (both volumes were 20 mL). Under the protection of argon, the temperature was rapidly increased. During this process, at about 170 °C, the solution changed from a turbid light brown to a yellow transparent solution. When the temperature reached 180 °C, 16 mL of 1.0 mol·L -1 Te source precursor Te-TOP prepared in step (1a) was injected into the cationic solution of Ag and Sb according to the molar ratio of Ag, Sb, and Te of 1:1:2. The reaction time was 60 min at 180 °C, and after completion, it was cooled to room temperature in a water bath.

[0054] d. The solution after the reaction was cooled and centrifugally washed using n-hexane as a dispersant and absolute ethanol as a precipitant. The volume ratio of n-hexane to absolute ethanol was 1:1, and it was centrifugally washed 3 times at a rotation speed of 9000 rpm for 5 min each time. Finally, the obtained AgSbTe2 nanoparticles were transferred to a vacuum drying oven and dried at 60 °C for 6 h. This reaction with doubled scale finally yielded approximately 3.5 g of AgSbTe2 nanomaterial powder, and the yield was also close to 90% of the theoretical yield.

[0055] Example 3

[0056] A method for preparing AgSbTe2 nanomaterials by a solution method. The difference between this example and Example 1 is that in step d of Example 1, when the solution changed from a turbid light brown to a yellow transparent solution at 170 °C, 8 mL of 1.0 mol·L -1 Te source precursor Te-TOP prepared in step 1a was injected into the cationic solution of Ag and Sb according to the molar ratio of Ag, Sb, and Te of 1:1:2. The reaction time was 60 min at 170 °C, and after completion, it was cooled to room temperature in a water bath. The remaining steps were the same as those in Example 1.

[0057] In the present invention, whether magnifying or reducing the multiples of the reactants, using oleylamine and ethanethiol as solvents to prepare the cationic molecular ligand precursor is effective, and their volume ratio is set to 3 - 4. In addition, the degassing temperature of oleylamine is set at 100 - 130 °C, the final reaction temperature is controlled at 170 - 190 °C, and the reaction time is 50 - 70 min. These parameter ranges can all effectively implement the present invention. For the sake of brevity, not all examples are listed one by one. For specific situations where the present invention cannot be implemented, please refer to the comparative example part in the description to understand the differences in relevant raw materials and reaction conditions.

[0058] The preparation methods of AgSbTe2 nanomaterials in the comparative examples were compared with those in Examples 1-3. In all comparative examples, pure-phase AgSbTe2 nanomaterials could not be prepared. The present invention specifically lists 4 cases for illustration. All the anion precursors Te-TOP were the same as those in Examples 1-3, and mainly included the following steps:

[0059] Comparative Example 1

[0060] Step 1. Preparation of cation and anion precursors, including the following steps:

[0061] a. The preparation of the 1.0 mol·L -1 anion Te precursor was the same as that in Examples 1-3.

[0062] Step 2. Preparation of AgSbTe2 nanomaterials by liquid-phase method, including the following steps:

[0063] b. First, 5 mmol of AgNO3 and 5 mmol of SbCl3 were added to a three-necked flask containing 70 mL of oleylamine, magnetically stirred at room temperature for 20 min, and evacuated and purged with argon three times. Subsequently, the temperature was raised to 120 °C under vacuum for 60 min to remove the low-boiling substances therein, and then argon was introduced. Subsequently, when the temperature was rapidly raised to 220 °C, 10 mL of the pre-prepared Te source precursor Te-TOP in step (1a) was injected into the cation solution of Ag and Sb according to the molar ratio of Ag:Sb:Te of 1:1:2. The reaction time was 60 min at 220 °C, and after completion, it was cooled to room temperature in a water bath.

[0064] c. The conditions of centrifugal washing and vacuum drying of the solution after the reaction was cooled were the same as those in Examples 1-3.

[0065] Comparative Example 2

[0066] Step 1. Preparation of cation and anion precursors, including the following steps:

[0067] a. The preparation of the 1.0 mol·L -1 anion Te precursor was the same as that in Examples 1-3.

[0068] b. The preparation of the 0.4 mol·L -1 molecular ligand solution of Ag and Sb was the same as that in Examples 1-3.

[0069] Step 2. Preparation of AgSbTe2 nanomaterials by liquid-phase method, including the following steps:

[0070] c. First, evacuate and degas 70 mL of oleylamine at 120 °C for 60 min to remove the low-boiling substances therein, and then introduce argon. Subsequently, inject the molecular ligand solution of 0.4 mol·L -1 cationic Ag and Sb prepared in step (1b) of Comparative Example 2 into this oleylamine in a molar ratio of 1:1 (both volumes are 10 mL), and rapidly heat up under argon protection. During this process, the solution changes from a turbid light brown to a yellow transparent solution at about 170 °C. When the temperature reaches 220 °C, inject 8 mL of the pre-prepared Te source precursor Te-TOP of 1.0 mol·L -1 prepared in step (1a) into the cationic solution of Ag and Sb according to the molar ratio of Ag, Sb and Te of 1:1:2. React at 220 °C for 60 min, and then cool to room temperature in a water bath.

[0071] d. The centrifugal washing and vacuum drying conditions of the solution after the reaction is cooled are the same as those in Examples 1-3.

[0072] Comparative Example 3

[0073] Step 1. Preparation of cationic and anionic precursors, including the following steps:

[0074] a. The preparation of the 1.0 mol·L -1 anionic Te precursor is the same as that in Examples 1-3.

[0075] b. First, evacuate and degas 20 mL of oleylamine at 120 °C for 60 min to remove the low-boiling substances therein, and then introduce argon. Secondly, in a glass bottle filled with argon, weigh 2.0 mmol of Ag2O and Sb2O3 powders respectively, and add them to a mixed solution of 8 mL of degassed oleylamine and 2 mL of ethanedithiol. The volume ratio of oleylamine to ethanedithiol is 4:1. Stir magnetically at room temperature for 12 h until it is completely clear and transparent. Finally, prepare a molecular ligand solution of Ag and Sb with a concentration of 0.4 mol·L -1

[0076] Step 2. Preparation of AgSbTe2 nanomaterials by liquid phase method, including the following steps:

[0077] c. First, evacuate and degas 70 mL of oleylamine at 120 °C for 60 min to remove the low-boiling substances therein, and then introduce argon. Subsequently, inject the 0.4 mol·L -1The molecular ligand solution of cationic Ag and Sb is injected into the oleylamine at a molar ratio of 1:1 (both with a volume of 10 mL), and the temperature is rapidly increased under argon protection. During this process, the solution changes from a turbid light brown to a yellow transparent solution at about 170 °C. When the temperature reaches 180 °C, 8 mL of the Te source precursor Te-TOP prepared in step (1a) with a concentration of 1.0 mol·L -1 is injected into the cationic solution of Ag and Sb according to the molar ratio of Ag, Sb, and Te of 1:1:2. The reaction time is 60 min at 180 °C, and after that, it is cooled to room temperature in a water bath.

[0078] d. The solution after the reaction is centrifuged, washed, and the vacuum drying conditions are the same as those in Examples 1-3.

[0079] Comparative Example 4

[0080] Step 1. Preparation of cationic and anionic precursors, including the following steps:

[0081] a. The preparation of the anionic Te precursor with a concentration of 1.0 mol·L -1 is the same as that in Examples 1-3.

[0082] b. The preparation of the molecular ligand solution of Ag and Sb with a concentration of 0.4 mol·L -1 is the same as that in Examples 1-3.

[0083] Step 2. Preparation of AgSbTe2 nanomaterials by a liquid-phase method, including the following steps:

[0084] c. First, 70 mL of oleylamine is evacuated and degassed at 120 °C for 60 min to remove the low-boiling substances therein, and then argon is introduced. Subsequently, the molecular ligand solution of cationic Ag and Sb with a concentration of 0.4 mol·L -1 prepared in step (1b) of Comparative Example 4 is injected into the oleylamine at a molar ratio of 1:1 (both with a volume of 10 mL). The temperature is rapidly increased under argon protection. During this process, the solution changes from a turbid light brown to a yellow transparent solution at about 170 °C. When the temperature reaches 180 °C, 8 mL of the Te source precursor Te-TOP prepared in step (1a) with a concentration of 1.0 mol·L -1 is injected into the cationic solution of Ag and Sb according to the molar ratio of Ag, Sb, and Te of 1:1:2. The reaction time is 180 min at 180 °C, and after that, it is cooled to room temperature in a water bath.

[0085] d. The solution after the reaction is centrifuged, washed, and the vacuum drying conditions are the same as those in Examples 1-3.

[0086] Through the detailed analysis of Examples 1-3 and Comparative Examples 1-4, combined with Figure 6The presented X-ray diffraction pattern (XRD) results, Table 1 shows the corresponding products of Examples 1-3 and Comparative Examples 1-4. All the implementation parameters and reaction conditions are listed in detail in this table, and the corresponding relationships between the products of each example and comparative example are clarified. All the anion precursors in the examples and comparative examples are Te-TOP with a concentration of 1.0 mol·L -1 and the concentrations of Ag and Sb cation precursors are both 0.4 mol·L -1 . The reaction solvent is oleylamine in all cases, so it is not listed in this table. The difference between Example 2 and Example 1 is that Example 2 is a reaction with an amplification factor. The prepared products of Comparative Examples 1-4 in the table are arranged in the order of the main phase and the secondary phase. OLA in the table represents oleylamine, EtSH represents ethanethiol, and EDT represents ethylene dithiol.

[0087] Table 1 Results of the Prepared Products of Examples 1-3 and Comparative Examples 1-4

[0088]

[0089] As Figure 6 shown, the products obtained in Comparative Examples 1-4 all contain impurity phases of Ag2Te and Sb2Te3. Specifically, in Comparative Example 1, in addition to the peaks of the main phase AgSbTe2, there are obvious Ag2Te phase and Sb2Te3 phase; in Comparative Example 2, the main phase is mainly Ag2Te phase and Sb2Te3 phase, and the peak of AgSbTe2 is extremely low; in Comparative Example 3, the main phase is Sb2Te3 phase, and the contents of Ag2Te phase and AgSbTe2 phase are relatively low; in Comparative Example 4, the main phase is Sb2Te3 phase and AgSbTe2 phase, and in addition, there is a small amount of Ag2Te phase; the preparation result of Example 1 is a pure phase of AgSbTe2.

[0090] The above content is only an example and illustration of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution. As long as it does not deviate from the structure of the present invention or exceed the scope defined by this claims, it should fall within the protection scope of the present invention.

Claims

1. A method for preparing AgSbTe2 nanomaterials by a solution method, characterized in that, It includes the following steps: (1) Preparation of cationic and anionic precursors At room temperature, dissolve Te grains in trioctylphosphine in a glove box and stir to obtain a Te source precursor; At room temperature, under an argon atmosphere, add Ag2O and Sb2O3 to a mixed solution of oleylamine and ethanethiol with a certain volume ratio respectively, and stir to obtain a molecular ligand solution of Ag and Sb, which is the cationic precursor; (2) Preparation of AgSbTe2 nanomaterials by liquid phase method After degassing oleylamine under vacuum for a certain time at a certain temperature, introduce argon, inject the cationic Ag and Sb molecular ligand solutions into the oleylamine solvent according to a molar ratio of 1:(0.98 - 1.02), then quickly raise the temperature to make the solution change from turbid light brown to yellow and transparent, and then add the Te source precursor for reaction. The reaction temperature is 170 - 190 °C, the reaction time is 50 - 70 min. After the reaction, centrifuge and wash, and dry under vacuum to obtain AgSbTe2 nanomaterials.

2. The method for preparing AgSbTe2 nanomaterials by a solution method according to claim 1, characterized in that: In the step (1), the concentration of the Te source precursor is 1.0 - 2.0 mol·L -1 , and the stirring time of the Te particles and tri-n-octylphosphine is 3 - 5 days.

3. The method for preparing AgSbTe2 nanomaterials by a solution method according to claim 1, characterized in that: In the step (1), the volume ratio of oleylamine to ethanethiol is (3 - 4):1 and the stirring time is 6 - 12 h.

4. The method for preparing AgSbTe2 nanomaterials by a solution method according to claim 1, characterized in that: In the step (2), under the temperature condition of 100 - 130 °C, the vacuum degassing time of oleylamine is not less than 30 min.

5. The method for preparing AgSbTe2 nanomaterials by a solution method according to claim 1, characterized in that: In the step (2), the molar ratio of Ag, Sb and Te is 1:(0.98 - 1.02):(2 - 2.05).

6. The method for preparing AgSbTe2 nanomaterials by a solution method according to claim 1, characterized in that: In the step (2), the washing is carried out by centrifugal washing with n - hexane and absolute ethanol for 2 - 4 times.

7. A method for preparing AgSbTe2 nanomaterials by a solution method according to claim 1, characterized in that: In the step (2), the centrifugation speed is 7000 - 9000 rpm and the time is 5 - 10 min each time.

8. The method for preparing AgSbTe2 nanomaterials by a solution method according to claim 1, wherein: In the step (2), the drying is carried out by vacuum drying, the drying time is 4 - 8 hours, and the drying temperature is 60 - 80 °C.

Images