Tellurium-based heterojunction nanometer material and preparation method and application thereof

Abstract

The invention relates to the technical field of nanometer material synthesis, in particular to a tellurium-based heterojunction nanometer material and a preparation method and application thereof.The preparation method comprises the steps that a first tellurium crystal and a second tellurium crystal serve as a working electrode and a counter electrode respectively, the working electrode, the counter electrode, water and organic acid construct a dual-electrode electrochemical stripping system, and an alternating current power source is connected; and reacting to obtain the tellurium-based heterojunction nano material. Under the action of an electric field, organic acid slightly ionizes hydrogen ions in water, the hydrogen ions can serve as an intercalation reagent to intercalate tellurium crystals and become hydrogen under reduction potential, and expansion and stripping of tellurium are accelerated; the ionization degree of organic acid is low, movement of hydrogen ions in an electric field is remarkably constrained by anions of organic groups, stripping of tellurium crystals by the hydrogen ions under constraint is limited, and selectivity exists in intercalation gaps of a three-dimensional space, so that amorphous atom arrangement is presented at the edge, and internal crystals present crystallinity; the tellurium-based heterojunction nanometer material with the amorphous phase and the crystalline phase blended is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterial synthesis, and in particular to a tellurium-based heterojunction nanomaterial and a preparation method and application thereof. Background Art

[0002] Semiconductor tellurium crystals have attracted widespread attention due to their diverse chemical valence states, narrow band gaps, and tunable optoelectronic properties. Generally, the van der Waals forces between tellurium crystal chains are weak, while the covalent bonds within the chains are strong. This anisotropy in the forces between these two forces allows for size reduction via liquid-phase exfoliation, thereby yielding low-dimensional tellurium-based nanocomposites. For example, using isopropyl alcohol as a solvent, small two-dimensional tellurium nanosheets or nanoparticles can be obtained by water-bath sonication.

[0003] However, the surface phase structure of the nanomaterials obtained by the liquid phase exfoliation method is relatively simple, the atomic arrangement is relatively regular, there are only a small number of atomic vacancies or local atomic arrangement deformities, and the physical or chemical properties presented are relatively similar, making it difficult to achieve specific functionalization, such as the rapid transmission of electrons, ions or photogenerated carriers under gradient fields.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a tellurium-based heterojunction nanomaterial and its preparation method and application, aiming to solve the problem that the tellurium nanomaterials prepared by the existing methods have a relatively simple surface phase structure and a relatively regular atomic arrangement.

[0006] The technical solutions of the present invention are as follows: A method for preparing a tellurium-based heterojunction nanomaterial comprises the following steps: A dual-electrode electrochemical stripping system was constructed using the first tellurium crystal and the second tellurium crystal as the working electrode and the counter electrode, respectively, water as the solvent, and an organic acid as the intercalation reagent. An alternating current power supply is introduced into the dual-electrode electrochemical stripping system to obtain a tellurium-based heterojunction nanomaterial through reaction.

[0007] The method for preparing the tellurium-based heterojunction nanomaterial, wherein the organic acid is a monoacid or a polyacid; the organic acid contains one or more of an aromatic group, an alkyl group with at least three carbon atoms, and an unsaturated double bond with at least three carbon atoms.

[0008] In the method for preparing the tellurium-based heterojunction nanomaterial, the organic acid comprises one or more of octanoic acid, succinic acid, adipic acid, linolenic acid, cinnamic acid, oleic acid, stearic acid, linoleic acid, palmitic acid, and arachidonic acid.

[0009] The method for preparing the tellurium-based heterojunction nanomaterial, wherein the first tellurium crystal is a solid block or powder; the second tellurium crystal is a solid block or powder; Preferably, when the first tellurium crystal and / or the second tellurium crystal is a solid block, platinum wire is wound around the surface of the tellurium crystal to serve as the working electrode and the counter electrode; Preferably, when the first tellurium crystals and / or the second tellurium crystals are powders, the tellurium crystals are compounded with a binder and a conductive agent and then coated on a conductive support electrode to serve as the working electrode and the counter electrode.

[0010] The method for preparing the tellurium-based heterojunction nanomaterial, wherein the mass ratio of the organic acid to water is 1:(90-100).

[0011] The method for preparing the tellurium-based heterojunction nanomaterial, wherein the voltage of the AC power supply is ±(3-15)V, and the frequency of the AC power supply is 0.0001Hz-1000Hz.

[0012] The method for preparing the tellurium-based heterojunction nanomaterial, wherein the reaction time is 60-180 minutes, and the reaction is carried out at 25° C.-80° C.

[0013] A tellurium-based heterojunction nanomaterial is prepared by using the method for preparing the tellurium-based heterojunction nanomaterial.

[0014] The tellurium-based heterojunction nanomaterial has both amorphous and crystalline phase structures on its surface.

[0015] Application of a tellurium-based heterojunction nanomaterial in semiconductors, energy or biomedicine.

[0016] Beneficial effects: The present invention provides a tellurium-based heterojunction nanomaterial, a preparation method and application thereof. The preparation method of the tellurium-based heterojunction nanomaterial comprises the following steps: using a first tellurium crystal and a second tellurium crystal as a working electrode and a counter electrode, respectively, using water as a solvent, and using an organic acid as an intercalation reagent to construct a dual-electrode electrochemical stripping system; applying an AC power supply to the dual-electrode electrochemical stripping system, and obtaining the tellurium-based heterojunction nanomaterial through reaction. The present invention constructs structural functional materials using an electrochemical in-situ modification method to prepare a tellurium-based heterojunction nanomaterial with an amorphous phase-crystalline phase blend. The method mainly involves weakly ionizing hydrogen ions in water under the action of an electric field, which can serve as an intercalation agent to intercalate tellurium crystals and convert into hydrogen gas at a reduction potential, thereby accelerating the expansion and exfoliation of tellurium. Due to the low degree of ionization of the organic acid, the movement of hydrogen ions under the electric field is significantly constrained by the organic group anions, and the exfoliation of tellurium crystals by the constrained hydrogen ions is limited, resulting in a slow intercalation rate and selectivity in the intercalation gap in three-dimensional space, thereby resulting in an amorphous atomic arrangement at the edge and crystallinity in the internal crystal, thereby obtaining a tellurium-based heterojunction nanomaterial with an amorphous phase-crystalline phase blend. In addition, due to the rapid switching of the AC electric field voltage, both tellurium electrodes can undergo rapid exfoliation, thereby improving the tellurium exfoliation rate and final yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the process flow of a method for preparing a tellurium-based heterojunction nanomaterial according to the present invention; Figure 2 This is a SEM characterization image of the tellurium-based heterojunction nanomaterial prepared in Example 1; Figure 3 This is the SEM characterization image of the tellurium nanomaterial prepared in Comparative Example 1. DETAILED DESCRIPTION

[0018] The present invention provides a tellurium-based heterojunction nanomaterial, its preparation method, and application. To clarify the objectives, technical solutions, and effects of the present invention, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0019] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0020] like Figure 1As shown, the present invention provides a method for preparing a tellurium-based heterojunction nanomaterial, comprising the steps of: Step S10: constructing a dual-electrode electrochemical stripping system using the first tellurium crystal and the second tellurium crystal as the working electrode and the counter electrode, respectively, water as the solvent, and an organic acid as the intercalation reagent; Step S20: supplying an AC power source to the dual-electrode electrochemical stripping system to obtain a tellurium-based heterojunction nanomaterial through reaction.

[0021] In this embodiment, a structural functional material is constructed by an electrochemical in-situ modification method to prepare a tellurium-based heterojunction nanomaterial with an amorphous phase-crystalline phase blend. This is mainly achieved by weakly ionizing hydrogen ions in water under the action of an electric field, which can act as an intercalation agent to intercalate tellurium crystals and convert into hydrogen gas under a reduction potential, which can accelerate the expansion and exfoliation of tellurium. Due to the low degree of ionization of the organic acid, the movement of hydrogen ions under the electric field is significantly constrained by the organic group anions. The exfoliation of tellurium crystals by the constrained hydrogen ions is limited, and their intercalation rate is slow. There is selectivity in the intercalation gap in three-dimensional space, resulting in an amorphous atomic arrangement at the edge and crystallinity in the internal crystal, thereby obtaining a tellurium-based heterojunction nanomaterial with an amorphous phase-crystalline phase blend. Moreover, due to the rapid switching of the AC electric field voltage, both tellurium electrodes can undergo rapid exfoliation, thereby improving the tellurium exfoliation rate and final yield.

[0022] Specifically, the tellurium-based heterojunction nanomaterial obtained by this preparation method has a unique surface microstructure, that is, both amorphous and crystalline phase structures exist on the surface. The advantages of the amorphous phase mainly include: 1) Rapid charge transfer can be achieved; 2) Provide sufficient active sites for subsequent chemical or physical adsorption; 3) The amorphous phase changes the electronic structure of the original crystalline phase, thereby changing the light absorption and photoelectric conversion behavior, such as narrowing the band gap; 4) The chemical potential at the interface between the amorphous phase and the crystalline phase is different, which induces a built-in electric field and promotes carrier migration.

[0023] In some embodiments, the organic acid is a monobasic acid (R-COOH) or a polybasic acid (R-(COOH) n); the organic acid contains one or more of an aromatic group, an alkyl group containing at least three carbon atoms, and an unsaturated double bond containing at least three carbon atoms. That is, R is one or more of an aromatic group, an alkyl group containing at least three carbon atoms, and an unsaturated double bond containing at least three carbon atoms. Under the action of an electric field, the organic acid weakly ionizes hydrogen ions in water, which can act as an intercalation agent to intercalate tellurium crystals and convert into hydrogen gas at a reduction potential, accelerating the expansion and exfoliation of tellurium. Moreover, due to the low degree of ionization of the organic acid, the movement of hydrogen ions under the electric field is constrained by the organic group anions. The constrained hydrogen ions are restricted in their exfoliation of tellurium crystals, resulting in a slow intercalation rate and selectivity in the intercalation gap in three-dimensional space, resulting in an amorphous atomic arrangement at the edge and crystallinity in the internal crystals, thereby obtaining a tellurium-based heterojunction nanomaterial with a blend of an amorphous phase and a crystalline phase.

[0024] In a preferred embodiment, the organic acid includes but is not limited to one or more of caprylic acid, succinic acid, adipic acid, linolenic acid, cinnamic acid, oleic acid, stearic acid, linoleic acid, palmitic acid, and arachidonic acid.

[0025] In some embodiments, the first tellurium crystal and the second tellurium crystal are high-purity tellurium crystals, with a purity greater than or equal to 99% or 99.9%.

[0026] In some embodiments, the first tellurium crystal is a solid block or powder; the second tellurium crystal is a solid block or powder; both solid block and powdered tellurium crystals can be used as working electrodes and counter electrodes; but powdered tellurium crystals need to be compounded with an adhesive and a conductive agent and then coated on a conductive support electrode before they can be used as working electrodes and counter electrodes.

[0027] Preferably, when the first tellurium crystal and / or the second tellurium crystal is a solid block, platinum wire is wrapped around the surface of the tellurium crystal to serve as the working electrode and the counter electrode; winding platinum wire on the surface of the tellurium crystal can improve the conductivity of the electrode, and solid block tellurium crystals not wrapped with platinum wire can also be directly used as the working electrode and the counter electrode.

[0028] Preferably, when the first tellurium crystals and / or the second tellurium crystals are powders, the tellurium crystals are compounded with a binder and a conductive agent and then coated on a conductive support electrode to serve as the working electrode and the counter electrode.

[0029] In some embodiments, the adhesive includes but is not limited to polyvinylidene fluoride or its copolymer, naphthalene, etc.; the conductive agent includes but is not limited to common conductive solid powders such as conductive carbon black, carbon nanotubes, MXene, graphene, etc.; the conductive support electrode includes but is not limited to common highly conductive, porous or dense conductive carriers such as copper foil, aluminum foil, foam copper, foam nickel, etc.

[0030] In some embodiments, the mass ratio of tellurium crystals to the binder and the conductive agent is 80:(5-10):(10-15); after mixing according to this mass ratio and coating on a conductive support electrode, a working electrode and a counter electrode with good conductivity can be obtained.

[0031] In a preferred embodiment, the mass ratio of tellurium crystals to the adhesive and the conductive agent is 80:10:10.

[0032] Specifically, tellurium crystals are mixed with the binder and the conductive agent in N,N-dimethylformamide with a solid content ratio of 0.5-1 mg / mL. After being evenly dispersed, the mixture is coated on the conductive support electrode and vacuum dried at a temperature of 80°C-110°C for 24-48 hours to obtain a tellurium-based electrode. The tellurium-based electrode can be used as a working electrode and a counter electrode.

[0033] In some embodiments, the mass ratio of the organic acid to water is 1:(90-100). The volume ratio of the organic acid to water is controlled so that the organic acid weakly ionizes hydrogen ions in the water under the action of the electric field, acts as an intercalation agent to intercalate the tellurium crystals, and converts to hydrogen gas under the reduction potential, accelerating the expansion and exfoliation of the tellurium.

[0034] In some embodiments, the AC power supply has a voltage of ±(3-15)V and a frequency of 0.0001Hz-1000Hz. By regulating the voltage and frequency, the speed of tellurium electrode exfoliation can be controlled to meet actual production requirements. Furthermore, at a voltage of ±(3-15)V, organic acids can weakly ionize hydrogen ions in water, acting as intercalation agents to intercalate tellurium crystals. At a reduction potential, these acids convert to hydrogen gas, accelerating tellurium expansion and exfoliation.

[0035] In a preferred embodiment, the voltage of the AC power supply is ±12V, and the frequency of the AC power supply is 0.1 Hz.

[0036] In some embodiments, the reaction time is 60-180 minutes, and the reaction is carried out at 25° C.-80° C. Within this reaction time and temperature, the tellurium crystals can be completely exfoliated to obtain a tellurium-based heterojunction nanomaterial with an amorphous phase and a crystalline phase blend.

[0037] In some embodiments, in step S20, the mixed solution obtained after the reaction is vacuum filtered, washed with a solvent, and dried at room temperature to obtain a tellurium-based heterojunction nanomaterial having an amorphous phase and a crystalline phase blend.

[0038] In addition, the present invention also provides a tellurium-based heterojunction nanomaterial, which is prepared using the method for preparing the tellurium-based heterojunction nanomaterial.

[0039] In this embodiment, the tellurium-based heterojunction nanomaterial obtained by this preparation method has a special surface microstructure, that is, both amorphous and crystalline phase structures exist on the surface; this structure can achieve rapid charge transfer and provide sufficient active sites for subsequent chemical or physical adsorption; and the amorphous phase changes the electronic structure of the original crystalline phase, thereby changing the light absorption and photoelectric conversion behavior, such as narrowing the band gap; at the same time, the chemical potential at the interface between the amorphous phase and the crystalline phase is different, which induces a built-in electric field and promotes carrier migration.

[0040] In some embodiments, the surface of the tellurium-based heterojunction nanomaterial has both amorphous and crystalline phase structures.

[0041] In addition, the present invention also provides an application of a tellurium-based heterojunction nanomaterial in semiconductors, energy or biomedicine.

[0042] The present invention will be described in detail with reference to the following examples. It should also be understood that the following examples are only intended to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above disclosure of the present invention fall within the scope of protection of the present invention.

[0043] Example 1 This embodiment provides a tellurium-based heterojunction nanomaterial with an amorphous phase and a crystalline phase blend. The preparation steps are as follows: A high-purity platinum wire is wound around the surface of a solid block of high-purity tellurium crystal and used as a working electrode and a counter electrode. Water is used as a solvent and octanoic acid is used as an intercalation reagent to construct a two-electrode electrochemical stripping system. An alternating current with a voltage amplitude of 12V, a frequency of 0.1Hz, a time of 120 minutes, and a temperature of 50°C is applied to the two-electrode electrochemical stripping system. After reaction, a mixed solution containing an amorphous phase-crystalline phase blended tellurium-based heterojunction nanomaterial is obtained. The mixed solution is vacuum filtered and washed with a solvent (deionized water and anhydrous ethanol are used alternately), and then dried at room temperature to obtain the amorphous phase-crystalline phase blended tellurium-based heterojunction nanomaterial.

[0044] The tellurium-based heterojunction nanomaterial obtained in Example 1 was dispersed in a non-aqueous solvent and ultrasonically dispersed, and then dropped onto a copper mesh for microstructural characterization. The SEM characterization diagram is shown in FIG. Figure 2 shown.

[0045] It can be seen that when octanoic acid is used as the electrolyte, it forms a milky white oil-water mixed phase with water, and electrochemical stripping occurs at the interface between the two. In this embodiment, the stripping rate of tellurium is slow, and the color of the solution gradually changes from milky white to dark brown. The product after stripping presents a two-dimensional sheet structure (such as Figure 2As shown in a in the figure); Under further magnification, the surface of this tellurium-based heterojunction nanomaterial presents a mixed phase of a crystalline phase with regular atomic arrangement and an amorphous phase with amorphous arrangement (as shown in a in the figure); Figure 2 In addition, most of the amorphous components present atomic cluster structures (such as Figure 2 (as shown in c in the figure).

[0046] Comparative Example 1 This comparative example is substantially the same as Example 1, except that octanoic acid is replaced with hydrochloric acid to prepare tellurium nanomaterials.

[0047] The tellurium nanomaterial obtained in Comparative Example 1 was dispersed in a non-aqueous solvent and ultrasonically dispersed, and then dropped onto a copper mesh for microstructural characterization. The SEM characterization diagram is shown in FIG. Figure 3 shown.

[0048] It can be seen that using hydrochloric acid as the electrolyte, it can form a homogeneous solution with water, the stripping speed is relatively fast, and the surface of the stripped product is mainly composed of crystalline components, with less amorphous phase, defect phase or other atomic arrangement deformities. In addition, it should be noted that the stripping product structures of other inorganic acids, including sulfuric acid, perchloric acid, phosphoric acid, carbonic acid or dihydrogen phosphate or their corresponding salts are similar. This type of tellurium-based material belongs to the traditional class of classic homogeneous materials.

[0049] Furthermore, under standard sunlight, the photothermal temperature of the tellurium nanomaterial dispersion obtained by hydrochloric acid stripping in Comparative Example 1 increased by 15°C, while the photothermal temperature of the tellurium-based heterojunction nanomaterial dispersion obtained by octanoic acid stripping in Example 1 increased by 19°C. This indicates that, at the same tellurium content, the tellurium nanomaterial stripped by organic acid exhibits a higher photothermal temperature than that stripped by inorganic acid. Furthermore, the tellurium material dispersion obtained by organic acid stripping exhibits greater chemical stability and dispersibility, and is less susceptible to degradation in water.

[0050] In summary, the present invention provides a tellurium-based heterojunction nanomaterial, its preparation method, and application. The preparation method of the tellurium-based heterojunction nanomaterial includes the following steps: using tellurium crystals as working electrodes and counter electrodes, water as a solvent, and an organic acid as an intercalation reagent to construct a dual-electrode electrochemical stripping system; passing an AC power supply into the dual-electrode electrochemical stripping system to obtain the tellurium-based heterojunction nanomaterial through reaction. The present invention constructs structural functional materials using an electrochemical in-situ modification method to prepare a tellurium-based heterojunction nanomaterial with an amorphous phase-crystalline phase blend. The method mainly involves weakly ionizing hydrogen ions in water under the action of an electric field, which can serve as an intercalation agent to intercalate tellurium crystals and convert into hydrogen gas at a reduction potential, thereby accelerating the expansion and exfoliation of tellurium. Due to the low degree of ionization of the organic acid, the movement of hydrogen ions under the electric field is significantly constrained by the organic group anions, and the exfoliation of tellurium crystals by the constrained hydrogen ions is limited, resulting in a slow intercalation rate and selectivity in the intercalation gap in three-dimensional space, thereby resulting in an amorphous atomic arrangement at the edge and crystallinity in the internal crystal, thereby obtaining a tellurium-based heterojunction nanomaterial with an amorphous phase-crystalline phase blend. In addition, due to the rapid switching of the AC electric field voltage, both tellurium electrodes can undergo rapid exfoliation, thereby improving the tellurium exfoliation rate and final yield.

[0051] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a tellurium-based heterojunction nanomaterial, characterized in that: Including steps: A dual-electrode electrochemical stripping system was constructed using the first tellurium crystal and the second tellurium crystal as the working electrode and the counter electrode, respectively, water as the solvent, and an organic acid as the intercalation reagent. An alternating current power supply is introduced into the dual-electrode electrochemical stripping system to obtain a tellurium-based heterojunction nanomaterial through reaction.

2. The method for preparing tellurium-based heterojunction nanomaterials according to claim 1, wherein: The organic acid is a monoacid or a polyacid; the organic acid contains one or more of an aromatic group, an alkyl group with at least three carbon atoms, and an unsaturated double bond with at least three carbon atoms.

3. The method for preparing tellurium-based heterojunction nanomaterials according to claim 1, wherein: The organic acid includes one or more of caprylic acid, succinic acid, adipic acid, linolenic acid, cinnamic acid, oleic acid, stearic acid, linoleic acid, palmitic acid, and arachidonic acid.

4. The method for preparing tellurium-based heterojunction nanomaterials according to claim 1, wherein: The first tellurium crystal is a solid block or powder; the second tellurium crystal is a solid block or powder; Preferably, when the first tellurium crystal and / or the second tellurium crystal is a solid block, platinum wire is wound around the surface of the tellurium crystal to serve as the working electrode and the counter electrode; Preferably, when the first tellurium crystals and / or the second tellurium crystals are powders, the tellurium crystals are compounded with a binder and a conductive agent and then coated on a conductive support electrode to serve as the working electrode and the counter electrode.

5. The method for preparing tellurium-based heterojunction nanomaterials according to claim 1, wherein: The mass ratio of the organic acid to water is 1:(90-100).

6. The method for preparing tellurium-based heterojunction nanomaterials according to claim 1, wherein: The voltage of the AC power supply is ±(3-15)V, and the frequency of the AC power supply is 0.0001Hz-1000Hz.

7. The method for preparing tellurium-based heterojunction nanomaterials according to claim 1, characterized in that: The reaction time is 60-180 minutes, and the reaction is carried out at 25°C-80°C.

8. A tellurium-based heterojunction nanomaterial, characterized in that: The tellurium-based heterojunction nanomaterial is prepared using the preparation method according to any one of claims 1 to 7.

9. The tellurium-based heterojunction nanomaterial according to claim 8, characterized in that: The surface of the tellurium-based heterojunction nanomaterial has both amorphous and crystalline phase structures.

10. Use of the tellurium-based heterojunction nanomaterial according to any one of claims 8 to 9 in semiconductors, energy or biomedicine.

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