Preparation method and application of axially ordered metal / semiconductor heterojunction

Abstract

The invention discloses a preparation method and application of an axially ordered metal / semiconductor heterojunction, and belongs to the field of preparation of nano materials. The method comprises the following steps: firstly, providing an axially ordered semiconductor / semiconductor heterojunction as a template, and then carrying out cation exchange to obtain a target axially ordered semiconductor / semiconductor heterojunction; the preparation method comprises the following steps: mixing a target axial ordered semiconductor / semiconductor heterojunction dispersion liquid and a saturated aliphatic amine ligand to form a water-free and oxygen-free condition, then introducing inert gas, adding mercaptan and an organic phosphine ligand, heating to 200-240 DEG C, and reacting for 1-5 minutes to obtain the metal / semiconductor heterojunction which completely retains the axial ordered configuration. The method described by the invention is simple, mild and controllable, the preparation of the axially ordered metal / semiconductor heterostructure is realized for the first time, and the prepared axially ordered metal / semiconductor heterostructure with different segment numbers shows obviously different optical absorption properties and electron transmission properties.

Description

Technical Field

[0001] This invention relates to a method for preparing an Ag / sulfide heterojunction material, belonging to the field of nanomaterials, and also to the application of this heterojunction material. This invention is a divisional application of the invention patent application filed on August 27, 2025, with application number 2025112079775, entitled "A Method for Preparing and Applying an Ag / sulfide Heterojunction Material". Background Technology

[0002] Metal / semiconductor nanoheterostructures are a class of nanostructures formed by covalently linking metal nanomaterials and semiconductor nanomaterials onto a single nanosystem. In recent years, they have been widely used in fields such as photocatalytic energy conversion, organic catalysis, photoelectric sensors, and biomedicine.

[0003] Currently, the controlled synthesis methods for metal / sulfide heterostructures mainly include chemical reduction deposition and photoinduced reduction deposition on semiconductor substrates, and direct heterogeneous nucleation growth on metal substrates (Rational Tuning of Metal-Semiconductor Nano-Icosapods for Plasmon-Induced Photodetection. Chem. Mater. 2023, 35, 14, 5602–5611). The latter is an ideal method for controllably constructing metal / sulfide heterostructure nanomaterials with clear interfaces in solution phases. However, this method usually requires special metal particles as seeds and precise control of the growth environment in the solution phase at high temperatures to balance the nucleation and growth rates of the semiconductor on the metal surface in order to obtain metal / sulfide heterostructure materials. The operation steps are difficult and the preparation is cumbersome. Therefore, it is necessary to explore simple and suitable methods to prepare metal / sulfide heterostructure materials.

[0004] An epitaxial interface refers to the atomic-level contact interface formed between a second material and a first material, where the lattice orientation of the second material is highly consistent with that of the first material. Nanostructures with epitaxial interfaces exhibit excellent performance in fields such as plasma, electronics, optoelectronics, and catalysis. Typically, the synthesis of semiconductor / semiconductor heterojunctions, metal / metal heterojunctions, and metal / semiconductor nanostructures with epitaxial interfaces follows epitaxial growth theory. Their preparation methods mainly include solution methods and chemical vapor deposition, requiring specific morphologies and structures of seed crystals and strict conditions such as exposed crystal faces. The preparation of metal / semiconductor heterojunctions with epitaxial interfaces is particularly difficult, mainly because the large lattice mismatch between them severely hinders the orientational growth of both. To date, only a few cases have achieved the formation of metal / semiconductor heterojunctions with epitaxial interfaces under large lattice mismatches, such as Au / TiO2, Pt / MoS2, and Ag / CdS. Current epitaxial interfaces require precise control of the reaction precursors and reaction environment, as well as balancing nucleation and growth rates, to selectively grow metal components on semiconductor surfaces. This approach cannot meet the needs of many metal / semiconductor heterojunctions with epitaxial interfaces in electronic information and optoelectronic devices. Therefore, developing a method for preparing metal / semiconductor heterojunction nanomaterials with epitaxial interfaces is of great significance.

[0005] Axially ordered heterojunctions refer to ordered heterostructures formed by the orderly stacking of different compositions and crystal structures along the axial direction of a one-dimensional material in a block-to-block manner. These heterostructures possess continuously distributed and periodically alternating interfacial energy that can induce the ordered, directional separation and ultrafast transfer of photoexcited charge carriers within the bulk phase, thereby improving the material's photoelectric conversion efficiency and catalytic performance. Currently developed axially ordered heterojunction materials include semiconductor-semiconductor or metal-metal heterojunctions, specifically categorized as axial bisegment pn heterojunctions, axial segmented multiphase heterojunctions, axial kinked heterojunctions, axial superlattice heterojunctions, and axial regioselective shell heterojunctions. These materials have shown broad application prospects in photoelectrocatalytic water splitting for hydrogen production, carbon dioxide reduction, and detection devices. Compared to axially ordered semiconductor / semiconductor heterojunction materials, axially ordered metal / semiconductor heterojunction materials can further enhance carrier migration rates and improve photoelectric energy conversion efficiency. However, to date, the preparation methods and applications of axially ordered metal / semiconductor heterojunction materials have not been reported. This is mainly because it is currently difficult to grow both metal and semiconductor heterojunctions in an ordered manner within a composite material system using methods such as photodeposition, chemical deposition, and direct heterogeneous nucleation. Therefore, developing a method for preparing axially ordered metal / semiconductor heterojunctions is of great significance. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for preparing Ag / sulfide heterojunction materials to simplify the synthesis method of metal / semiconductor heterojunction materials; it also provides an Ag / sulfide heterojunction material and its application; this invention provides a method for preparing metal / semiconductor heterojunctions to stably synthesize lattice-matched epitaxial interface metal / semiconductor heterojunctions under mild conditions, and also provides a metal / semiconductor heterojunction with an epitaxial interface and its application; this invention provides a method for preparing axially ordered metal / semiconductor heterojunctions, which achieves mild and controllable synthesis of axially ordered metal / semiconductor heterojunctions, and also provides axially ordered metal / semiconductor heterojunctions with different numbers of segments prepared by this method and their applications.

[0007] Technical solution: The preparation method of Ag / sulfide heterojunction material of the present invention includes the following steps: under anhydrous and oxygen-free conditions, Ag2S / sulfide heterojunction is mixed with unsaturated aliphatic olefins and unsaturated aliphatic amines to form a first mixture, an organophosphorus is added to the first mixture, the temperature is raised to 150~200℃, the reaction is carried out for no less than 10 minutes, the mixture is cooled, and the solid is taken to obtain Ag / sulfide heterojunction.

[0008] Preferably, the Ag2S / sulfide heterojunction is one or a mixture of Ag2S / CdS heterojunction, Ag2S / ZnS heterojunction, and Ag2S / ZnCdS heterojunction.

[0009] Preferably, the ratio of Ag2S / sulfide heterojunction, organophosphorus, and unsaturated aliphatic amine is 1:1.1~5:1.1~7.

[0010] Preferably, the method for forming anhydrous and oxygen-free conditions is as follows: heating the first mixture to 100~120°C and maintaining it for 30~60 minutes.

[0011] Preferably, before adding organophosphorus compounds, an inert gas is introduced into the first mixture to cool it to 70-90°C.

[0012] Preferably, the unsaturated fatty olefin is 1-octadecene, the unsaturated fatty amine is oleylamine, and the organophosphorus is tri-n-octylphosphorus.

[0013] Preferably, the preparation method of the Ag2S / ZnS heterojunction is as follows: Ag(dedc), Zn(dedc)2, 1-dodecylthiol and oleic acid are mixed to form a fourth mixture, and the second mixture is heated to 200~250℃ and reacted for 30~60 minutes to obtain the Ag2S / ZnS heterojunction. The diameter of the heterojunction of the Ag2S / ZnS heterojunction increases with the increase of reaction temperature.

[0014] Preferably, the molar ratio of Ag(dedc) to Zn(dedc)2 is 1:10~20, and the addition ratio of 1-dodecylthiol and oleic acid relative to Ag(dedc) is 1mg:0.3~0.8mL.

[0015] Preferably, the preparation method of the Ag2S / CdS heterojunction is as follows: CdO, oleic acid, and octadecene are mixed to form a third mixed solution; an oleylamine dispersion of Ag2S and dibenzyl disulfide are mixed to form a fourth mixed solution; the third mixed solution is heated to 210-240°C, then cooled to 180-200°C; the fourth mixed solution is added to the third mixed solution, and the reaction is maintained at 180-200°C for 30-60 minutes to obtain the Ag2S / CdS heterojunction. After the fourth mixed solution is added to the third mixed solution, the molar ratio of Ag2S:CdO:dibenzyl disulfide in the reaction system is (1-50) × 10⁻⁶. -4 : twenty two.

[0016] Preferably, the preparation method of the Ag2S / ZnCdS heterojunction is as follows: Ag(dedc), Zn(dedc)2, Cd(dedc)2, 1-dodecylthiol (DDT) and oleic acid are mixed to form a fifth mixture. The fifth mixture is heated to 200~250℃ and reacted for 1 minute. Then, 10 mL of oleic acid is added, and the temperature is maintained at 200~250℃. The reaction is continued for 15~30 min to obtain the Ag2S / ZnCdS heterojunction.

[0017] The Ag / sulfide heterojunction material described in this invention is prepared by the aforementioned synthesis method.

[0018] The application of the Ag / sulfide heterojunction material described in this invention as a photosensitizer and photocatalyst.

[0019] Preferably, in order to ensure catalytic performance, when used as a photocatalyst, the boundary perimeter of the Ag / sulfide heterojunction material heterojunction is >17.0 nm.

[0020] The method for preparing an epitaxial interface metal / semiconductor heterojunction according to the present invention includes the following steps:

[0021] (1) Disperse the semiconductor / semiconductor heterojunction in a non-polar organic solvent, form a mixture with unsaturated fatty olefins and unsaturated fatty amines, heat to remove the non-polar organic solvent, remove oxygen and water;

[0022] (2) Add organophosphorus to the mixture, heat to 200~240℃, react for 10~30 minutes, cool, take the solid, and obtain a metal / semiconductor heterojunction.

[0023] Preferably, the semiconductor / semiconductor heterojunction is an Ag₂S / ZnS heterojunction with a one-dimensional nanowire structure; the metal / semiconductor heterojunction is an Ag / ZnS heterojunction.

[0024] Preferably, in order to improve the selectivity of the epitaxial interface, step (2) further includes adding thiols to the mixture, with the thiols added before the organophosphorus compounds, and the molar ratio between the semiconductor / semiconductor heterojunction, the thiols, and the organophosphorus compounds being 1:(0.3~3):(1~8). The amount of thiols added is less than that of the organophosphorus compounds.

[0025] More preferably, in order to balance epitaxial interface selectivity and yield, in step (2), the molar ratio between semiconductor / semiconductor heterojunction, thiol and organophosphine is 1:(0.5~1.0):(1~8).

[0026] Preferably, in step (2), after the thiol and unsaturated fatty olefin form a solution, it is added to the mixture, and the volume concentration of the thiol in the solution formed by the thiol and unsaturated fatty olefin is ≤50%vol.

[0027] Preferably, in step (1), the molar ratio between the semiconductor and the semiconductor heterojunction unsaturated aliphatic amine is 1:(5~20).

[0028] Preferably, in step (1), the heating conditions are: under vacuum conditions, the mixture is heated to 90~130°C and maintained for 30~60 minutes.

[0029] Preferably, in step (2), an inert gas is introduced to cool the mixture to 60~90°C, and then thiols and organophosphorus are added.

[0030] Preferably, the nonpolar organic solvent is toluene and / or n-hexane, the unsaturated fatty olefin is 1-octadecene, the unsaturated fatty amine is oleylamine, the organophosphorus is tri-n-octylphosphorus, and the thiol is n-dodecylthiol.

[0031] The epitaxial interface metal / semiconductor heterojunction described in this invention is prepared by the aforementioned method for preparing an epitaxial interface metal / semiconductor heterojunction.

[0032] The aforementioned epitaxial interface metal / semiconductor heterojunction can be used as a photocatalyst, as a photoelectric detection material, or as a biomedical material.

[0033] The present invention discloses a method for preparing an axially ordered metal / semiconductor heterojunction, comprising the following steps:

[0034] (1) Disperse the axially ordered semiconductor / semiconductor heterojunction in a non-polar organic solvent, form a mixture with unsaturated fatty olefins and unsaturated fatty amines, and remove the non-polar organic solvent, oxygen and water by heating;

[0035] (2) Mix the mixture obtained in step (1) with thiol and organophosphorus, heat to 200~240℃, react for 1~5 minutes, cool, take the solid, and obtain a metal / semiconductor heterojunction.

[0036] Preferably, the axially ordered semiconductor / semiconductor heterojunction is an Ag₂S / ZnS / (Ag₂S / ZnS) structure with a one-dimensional nanowire structure. n The heterojunction is a metal / semiconductor heterojunction of Ag / ZnS / (Ag / ZnS). n Heterogeneous junction, n≥1.

[0037] Preferably, in step (2), when 1≤n≤3, the molar ratio of semiconductor / semiconductor heterojunction, thiol, and organophosphorus is 1:0.05~1.6:2~5, and the proportion of thiol and organophosphorus added increases with the increase of n.

[0038] Preferably, when n=1, the molar ratio of semiconductor / semiconductor heterojunction, thiol, and organophosphine is 1: 0.12~0.45: 2~3; when n=2, the molar ratio of semiconductor / semiconductor heterojunction, thiol, and organophosphine is 1: 0.4~0.75: 3~5; when n=3, the molar ratio of semiconductor / semiconductor heterojunction, thiol, and organophosphine is 1: 0.8~1.1: 3~5.

[0039] Preferably, in step (2), after the thiol and unsaturated fatty olefin form a solution, it is added to the mixture, and the volume concentration of the thiol in the solution formed by the thiol and unsaturated fatty olefin is ≤25%vol.

[0040] Preferably, in step (1), the molar ratio of semiconductor / semiconductor heterojunction and unsaturated fatty amine is 1:1.1~7.

[0041] Preferably, in step (1), the operations of removing toluene, oxygen, and water are as follows: under vacuum conditions, the mixture is heated to 100~120°C and maintained for 30~60 minutes.

[0042] Preferably, the unsaturated fatty olefin is 1-octadecene, the unsaturated fatty amine is oleylamine, the nonpolar organic solvent is toluene and / or n-hexane, the organophosphorus is tri-n-octylphosphorus, and the thiol is n-dodecylthiol.

[0043] Preferably, in order to reduce the lattice mismatch at the interface between the metal and the semiconductor, in step (2), thiols are added to the mixture obtained in step (1) first, and then organophosphorus is added.

[0044] Preferably, in step (2), the method for obtaining the axially ordered semiconductor / semiconductor heterojunction is as follows: the axially ordered semiconductor / semiconductor heterojunction Ag2S / ZnS / (CdS / ZnS) is formed. n Equal volumes of dispersion and silver nitrate alcohol solution (in a volume ratio of 1:1) are mixed and subjected to a cation exchange reaction at 0–10 °C to obtain Ag₂S / ZnS / (AgS / ZnS). n .

[0045] Preferably, the silver nitrate alcohol solution is a silver nitrate methanol solution with a concentration of 0.1~1 mol / L, and the axially ordered semiconductor / semiconductor heterojunction Ag2S / ZnS / (CdS / ZnS) is... n The concentration of the dispersion should not exceed the concentration of the silver nitrate alcohol solution.

[0046] Preferably, the duration of the cation exchange reaction is 0.5 to 5 minutes.

[0047] Preferably, the axially ordered semiconductor / semiconductor heterojunction dispersion is Ag₂S / ZnS / (CdS / ZnS). n Toluene dispersion.

[0048] The axially ordered metal / semiconductor heterojunction described in this invention is prepared by the aforementioned method for preparing axially ordered metal / semiconductor heterojunctions.

[0049] The present invention relates to the application of an axially ordered metal / semiconductor heterojunction in photodetector devices.

[0050] Beneficial Effects: Compared with the prior art, the present invention has the following significant advantages: 1. The Ag / sulfide heterojunction material preparation method provided by the present invention uses only two ligands in the preparation process, directly obtaining the corresponding metal / sulfide heterojunction from the metal sulfide semiconductor material through chemical conversion. The preparation process is simple, does not require sacrificing other metals, and helps to reduce reagent costs; 2. Wide substrate applicability: not limited by the lattice mismatch between the metal and sulfide semiconductor; 3. The Ag / sulfide heterojunction material preparation method provided by the present invention is an in-situ preparation, preserving the structural characteristics of the raw material semiconductor / semiconductor heterojunction, and can... 4. The performance of the Ag / sulfide heterojunction catalyst can be adjusted by pre-adjusting the boundary perimeter of the semiconductor / semiconductor heterojunction; 5. The Ag / ZnS heterojunction provided by this invention can be clearly distinguished from the intrinsic absorption peak of semiconductor ZnS by the LSPR peak of the metal, and selective excitation can be achieved at a specific wavelength; 6. The Ag / ZnS catalyst prepared by the method of this invention can achieve a plasmon-induced catalytic hydrogen production rate of 585.4 μmol / g / h; 7. It does not require balancing the nucleation rate and growth rate, has good reproducibility, and is easier to control the boundary perimeter of the metal / sulfide semiconductor heterojunction than traditional synthesis methods. 7. The method for preparing epitaxial interface metal / semiconductor heterojunctions of the present invention does not require precise control of reaction conditions as in solution methods, is not affected by the exposure of crystal planes by seed crystals, has lower requirements for reaction kinetics and thermodynamics, and exhibits mild reaction conditions and good repeatability. 8. The method for preparing epitaxial interface metal / semiconductor heterojunctions of the present invention uses semiconductor / semiconductor heterojunctions as raw materials and utilizes ligand-assisted chemical transformation to obtain metal / semiconductor heterojunctions. Controlling the ligand ratio and addition order greatly improves the selectivity of the epitaxial interface. 9. It breaks through the limitations of traditional epitaxial interface preparation methods and provides a new approach for preparing metal / semiconductor heterojunctions with epitaxial interfaces. 10. The present invention provides a method for preparing axially ordered metal / semiconductor heterojunctions. This method breaks through the traditional metal / semiconductor heterojunction preparation methods, with milder and more controllable conditions, providing a new method and new approach for preparing metal / semiconductor heterojunctions. 11. The metal / semiconductor heterojunction material obtained by the present invention can completely retain the configuration of the template material. Attached Figure Description

[0051] Figure 1 Transmission electron microscope image of the Ag / CdS heterojunction prepared in Example 1;

[0052] Figure 2 Transmission electron microscope image of the Ag / ZnCdS heterojunction prepared in Example 3;

[0053] Figure 3 X-ray diffraction pattern of the Ag / CdS heterojunction prepared in Example 1;

[0054] Figure 4 The UV-Vis absorption spectra of the Ag / CdS and Ag2S / CdS heterojunctions prepared in Example 1 are shown.

[0055] Figure 5 X-ray diffraction pattern of the Ag / ZnCdS heterojunction prepared in Example 3;

[0056] Figure 6 The UV-Vis absorption spectra of the Ag / ZnCdS and Ag2S / ZnCdS heterojunctions prepared in Example 3 are shown below.

[0057] Figure 7 Transmission electron microscope image and diameter distribution diagram of the Ag / ZnS heterojunction prepared in Example 5;

[0058] Figure 8 Transmission electron microscope image and diameter distribution diagram of the Ag / ZnS heterojunction prepared in Example 7;

[0059] Figure 9 Transmission electron microscope image and diameter distribution diagram of the Ag / ZnS heterojunction prepared in Example 9;

[0060] Figure 10 X-ray diffraction patterns of Ag / ZnS heterojunctions prepared in Examples 5, 7 and 9;

[0061] Figure 11 UV-Vis absorption spectra of Ag / ZnS and Ag2S / ZnS heterojunctions prepared in Examples 5, 7 and 9;

[0062] Figure 12 Comparison of the performance of Ag / ZnS heterojunctions prepared in Examples 5, 7 and 9 in plasmonic photocatalytic hydrogen evolution;

[0063] Figure 13 This is a schematic diagram illustrating the principle of the preparation method of the metal / semiconductor heterojunction material of the present invention;

[0064] Figure 14 Transmission electron microscope image of the E-Ag / ZnS heterojunction prepared in Example 11;

[0065] Figure 15 Transmission electron microscope image of the N-Ag / ZnS heterojunction prepared in Example 15;

[0066] Figure 16 High-magnification transmission electron microscope image and corresponding selected area electron diffraction pattern of the E-Ag / ZnS heterojunction interface prepared in Example 11;

[0067] Figure 17High-magnification transmission electron microscope image and corresponding selected area electron diffraction pattern of the N-Ag / ZnS heterojunction interface prepared in Example 15;

[0068] Figure 18 Statistical results of epitaxial and non-epitaxy interfaces in E-Ag / ZnS and N-Ag / ZnS heterojunctions prepared in Examples 11 and 15;

[0069] Figure 19 X-ray diffraction patterns of E-Ag / ZnS and N-Ag / ZnS heterojunctions prepared in Examples 11 and 15;

[0070] Figure 20 The UV-Vis absorption spectra of the E-Ag / ZnS and N-Ag / ZnS heterojunctions prepared in Examples 11 and 15;

[0071] Figure 21 Comparison of the photoreduction properties of E-Ag / ZnS and N-Ag / ZnS heterojunctions for methyl viologen prepared in Examples 11 and 15;

[0072] Figure 22 Transmission electron microscope image of the product prepared in Comparative Example 2;

[0073] Figure 23 Transmission electron microscope image and diameter distribution diagram of the axially ordered Ag / ZnS / Ag / ZnS heterojunction prepared for Example 17;

[0074] Figure 24 The axial Ag / ZnS / (Ag / ZnS) prepared for Example 19 )2 Transmission electron microscope image and diameter distribution diagram of the heterojunction;

[0075] Figure 25 Axially ordered Ag / ZnS / (Ag / ZnS) prepared for Example 21 )3 Transmission electron microscope image and diameter distribution diagram of the heterojunction;

[0076] Figure 26 X-ray diffraction patterns of Ag / ZnS heterojunctions with different axial orders prepared in Examples 17, 19 and 21;

[0077] Figure 27 UV-Vis absorption spectra of Ag / ZnS heterojunctions with different axial orders prepared in Examples 17, 19 and 21;

[0078] Figure 28 Comparison of photoelectric response performance of Ag / ZnS heterojunctions with different axial orders prepared in Examples 17, 19 and 21 under plasmonic light irradiation;

[0079] Figure 29 Transmission electron microscope image of the Ag / ZnS / (Ag / ZnS)3 heterojunction prepared in Comparative Example 4;

[0080] Figure 30 Transmission electron microscope image of the Ag / ZnS / (Ag / ZnS)3 heterojunction prepared for Comparative Example 5. Detailed Implementation

[0081] The technical solution of the present invention will be further described below with reference to the accompanying drawings. In the following examples, the preparation method of the raw material Ag2S / CdS is as follows: First, Ag(dedc) (143 mg) and 9 mL of 1-dodecylthiol (DDT) are added to a three-necked flask, stirred and rapidly heated to 220°C at a heating rate of 10-15°C / min, and reacted for 5 min to obtain Ag2S particles. The Ag2S particles are washed with toluene and then dispersed in an oleylamine solution. dedc is diethyldithiocarbamate.

[0082] Step 2: Add 0.2 mmol of cadmium oxide, 2 mL of oleic acid, and 8 mL of octadecene to a three-necked flask, stir, and heat to 120°C under vacuum for 30 min. Then, introduce an inert gas and raise the temperature to 230°C. After the solution becomes clear, cool it to 190°C. During this process, prepare a mixed solution of Ag₂S and dibenzyl disulfide: Take 50 μL (1×10⁻⁶) of Ag₂S from step 1. -3 0.2 mmol of dibenzyl disulfide and 2.5 mL of oleylamine were mixed and ultrasonically dispersed to form a mixed solution. The mixed solution was then rapidly injected into the above reaction system. Timing was started when the solution temperature returned to 190℃. Heating was stopped after 30-60 min to obtain Ag2S / CdS heterojunction.

[0083] The preparation method of Ag2S / ZnS heterojunction is as follows: Ag(dedc) (14.3 mg), Zn(dedc)2 (235.5 mg), and 9 mL of 1-dodecylthiol (DDT) are added to a three-necked flask, stirred, and heated to 200-250°C within 20 minutes. After about 5 minutes, 9 mL of oleic acid is added. After the temperature rises, the reaction is maintained for 30-60 minutes to obtain Ag2S / ZnS heterojunction. In Examples 6 to 10, the raw materials used are adjusted by controlling the heating temperature and adjusting the boundary perimeter. In Examples 11 to 16, the synthesis temperature of the raw materials is controlled at 230°C and the reaction time is 30 minutes.

[0084] Raw materials: Ag₂S / ZnS / (CdS / ZnS) nThe heterojunction was prepared as follows: Ag(dedc) (14.3 mg), Zn(dedc)₂ (235.5 mg), and 9 mL of 1-dodecylthiol (DDT) were added to a three-necked flask. The mixture was stirred and heated to 230°C over 20 minutes. After approximately 5 minutes, 9 mL of oleic acid was added. The reaction was continued for 30-60 minutes after the temperature returned to a stable level, yielding the Ag₂S / ZnS heterojunction. During the reaction, 40 mg of Cd(dedc)₂ was added to the reaction system multiple times to obtain Ag₂S / ZnS / (CdS / ZnS) n Heterojunction, where n is the number of times Cd(dedc)2 is added, and the time interval between two consecutive additions of Cd(dedc)2 is 18-22 min. (Method source: Pulsed axial Epitaxy of Colloidal Quantum Dots in Nanowires Enables Facet - Selective Passivation. Nat. Commun. 2018, 9, 4947. / CN113353968 A).

[0085] The preparation method of Ag2S / ZnCdS heterojunction is as follows: Ag(dedc) (14.3 mg), Zn(dedc)2 (90 mg), Cd(dedc)2 (100 mg), 5 mL DDT, and 10 mL oleic acid are added to a three-necked flask, stirred, and heated to 200~250℃ within 20 minutes. After about 1 minute, 10 mL of oleic acid is added. After the temperature rises, the reaction is maintained for 15-30 minutes to obtain Ag2S / ZnCdS heterojunction.

[0086] Example 1: 1 mL of the prepared Ag₂S / CdS heterojunction toluene dispersion (1 M concentration), 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was stirred and heated to 120 °C under vacuum for 30 min. Nitrogen gas was then introduced to cool the mixture to 90 °C, and 1 mL of tri-n-octylphosphine was injected. The temperature was then raised again to 160 °C. After reacting at this temperature for 5 min, the mixture was cooled to room temperature, centrifuged, and washed twice with toluene and n-hexane to obtain Ag / CdS heterojunctions dispersed in toluene solution. UV-Vis absorption and transmission electron microscopy were then performed.

[0087] Example 2: 1 mL of the prepared Ag₂S / CdS heterojunction toluene dispersion (1 M concentration), 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was stirred and heated to 100 °C under vacuum for 60 min. Nitrogen gas was then introduced to cool the mixture to 90 °C, and 0.5 mL of tri-n-octylphosphine was injected. The temperature was then raised again to 200 °C. After reacting at this temperature for 5 min, the mixture was cooled to room temperature, centrifuged, and washed twice with toluene and n-hexane to obtain Ag / CdS heterojunctions dispersed in toluene solution. UV-Vis absorption and transmission electron microscopy were then performed.

[0088] Example 3: 1 mL of the prepared Ag₂S / ZnCdS heterojunction toluene dispersion (1 M concentration), 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was stirred and heated to 120 °C under vacuum for 30 min. Nitrogen gas was then introduced to cool the mixture to 90 °C, and 1 mL of tri-n-octylphosphine was injected. The temperature was then raised again to 160 °C. After reacting at this temperature for 10 min, the mixture was cooled to room temperature, centrifuged, and washed twice with toluene and n-hexane to obtain Ag / ZnCdS heterojunctions dispersed in toluene solution. UV-Vis absorption and transmission electron microscopy were then performed.

[0089] Example 4: 1 mL of the prepared Ag₂S / ZnCdS heterojunction toluene dispersion (1 M concentration), 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was stirred and heated to 100 °C under vacuum for 30 min. Nitrogen gas was then introduced to cool the mixture to 90 °C, and 0.6 mL of tri-n-octylphosphine was injected. The temperature was then raised again to 180 °C. After reacting at this temperature for 10 min, the mixture was cooled to room temperature, centrifuged, and washed twice with toluene and n-hexane to obtain Ag / ZnCdS heterojunctions dispersed in toluene solution. UV-Vis absorption and transmission electron microscopy were then performed.

[0090] Example 5: 1 mL of Ag₂S / ZnS₁ heterojunction toluene dispersion (1 M concentration), prepared at 210 °C for 60 min, along with 6 mL of octadecene and 2 mL of oleylamine, were added to a 50 mL three-necked flask. The mixture was stirred and heated to 120 °C under vacuum for 30 min. Nitrogen gas was then introduced to cool the mixture to 90 °C, and 1 mL of tri-n-octylphosphine was injected. The temperature was then raised again to 170 °C. After reacting at this temperature for 10 min, the mixture was cooled to room temperature, centrifuged, and washed twice with toluene and n-hexane to obtain Ag / ZnS₁ heterojunctions dispersed in toluene solution. UV-Vis absorption and transmission electron microscopy were then performed.

[0091] Example 6: 1 mL of Ag₂S / ZnS₁ heterojunction toluene dispersion (1 M concentration), prepared at 210 °C for 60 min, along with 6 mL of octadecene and 2 mL of oleylamine, were added to a 50 mL three-necked flask. The mixture was stirred and heated to 120 °C under vacuum for 60 min. Nitrogen gas was then introduced to cool the mixture to 90 °C, and 2 mL of tri-n-octylphosphine was injected. The temperature was then raised again to 150 °C. After reacting at this temperature for 10 min, the mixture was cooled to room temperature, centrifuged, and washed twice with toluene and n-hexane to obtain Ag / ZnS₂ heterojunctions dispersed in toluene solution. UV-Vis absorption and transmission electron microscopy were then performed.

[0092] Example 7: 1 mL of Ag₂S / ZnS₂ heterojunction toluene dispersion (1 M concentration), prepared at 230 °C for 50 min, along with 6 mL of octadecene and 2 mL of oleylamine, were added to a 50 mL three-necked flask. The mixture was stirred and heated to 100 °C under vacuum for 60 min. Nitrogen gas was then introduced to cool the mixture to 90 °C, and 1 mL of tri-n-octylphosphine was injected. The temperature was then raised again to 170 °C. After reacting at this temperature for 10 min, the mixture was cooled to room temperature, centrifuged, and washed twice with toluene and n-hexane to obtain Ag / ZnS₃ heterojunctions dispersed in toluene solution. UV-Vis absorption and transmission electron microscopy were then performed.

[0093] Example 8: 1 mL of Ag₂S / ZnS₂ heterojunction toluene dispersion (1 M concentration), prepared at 230 °C for 50 min, along with 6 mL of octadecene and 2 mL of oleylamine, were added to a 50 mL three-necked flask. The mixture was stirred and heated to 110 °C under vacuum for 40 min. Nitrogen gas was then introduced to cool the mixture to 90 °C, and 1 mL of tri-n-octylphosphine was injected. The temperature was then raised again to 200 °C. After reacting at this temperature for 10 min, the mixture was cooled to room temperature, centrifuged, and washed twice with toluene and n-hexane to obtain Ag / ZnS₄ heterojunctions dispersed in toluene solution. UV-Vis absorption and transmission electron microscopy were then performed.

[0094] Example 9: 1 mL of Ag₂S / ZnS₃ heterojunction toluene dispersion (1 M concentration), prepared at 250 °C for 50 min, along with 6 mL of octadecene and 2 mL of oleylamine, were added to a 50 mL three-necked flask. The mixture was stirred and heated to 120 °C under vacuum for 60 min. Nitrogen gas was then introduced to cool the mixture to 90 °C, and 1 mL of tri-n-octylphosphine was injected. The temperature was then raised again to 170 °C. After reacting at this temperature for 10 min, the mixture was cooled to room temperature, centrifuged, and washed twice with toluene and n-hexane to obtain Ag / ZnS₅ heterojunctions dispersed in toluene solution. UV-Vis absorption and transmission electron microscopy were then performed.

[0095] Example 10: 1 mL of Ag₂S / ZnS-3 heterojunction toluene dispersion (1 M concentration), prepared at 250 °C for 50 min, along with 6 mL of octadecene and 2 mL of oleylamine, were added to a 50 mL three-necked flask. The mixture was stirred and heated to 120 °C under vacuum for 60 min. Nitrogen gas was then introduced to cool the mixture to 90 °C, and 2 mL of tri-n-octylphosphine was injected. The temperature was then raised again to 150 °C. After reacting at this temperature for 10 min, the mixture was cooled to room temperature, centrifuged, and washed twice with toluene and n-hexane to obtain Ag / ZnS-6 heterojunctions dispersed in toluene solution. UV-Vis absorption and transmission electron microscopy were then performed.

[0096] Material phase transfer: 10 mL of an aqueous solution containing 10 μL of 3-mercaptopropionic acid and 50 mg of potassium hydroxide was added to 10 mL of a chloroform solution containing 0.1 mmol Ag / ZnS. After shaking for 10 min, the mixture was centrifuged, washed with ethanol, and finally dispersed in water. Photocatalytic hydrogen evolution experiment: 0.1 mmol of metal / semiconductor heterojunction photocatalyst material with different boundary perimeters was mixed with 10 mL of a sodium sulfite solution (0.5 M) containing 20 vol% methanol and transferred to a 50 mL reactor. The mixture was bubbled with nitrogen for 30 min to remove air from the reaction system. Subsequently, the mixture was irradiated under simulated visible sunlight using a 300 W xenon lamp (Microsolar 300, Beijing Bofeilai Technology Co., Ltd.), with a 400 nm cutoff filter used to generate a visible light source (λ ≥ 400 nm), and the reaction temperature was maintained at 25 °C using a constant temperature water bath. The gases were analyzed by gas chromatography (Nexis GC-2030) equipped with a thermal conductivity detector.

[0097] The experimental results are as follows: The Ag / CdS heterojunction obtained in Example 1 was analyzed by transmission electron microscopy, such as... Figure 1 As shown, the heterojunction exhibits a slightly curved dot-rod structure, where the darker spherical black areas are metallic Ag particles, and the corresponding lighter-colored curved rod-shaped areas are CdS components. This structure indicates that the two form a stable heterostructure. X-ray diffraction analysis was performed on the Ag / CdS heterojunction material obtained in Example 1, and the results are as follows... Figure 3 As shown, the diffraction peaks of the prepared Ag / CdS material correspond one-to-one with the standard cards for wurtzite CdS (PDF#41-1049) and face-centered cubic Ag (PDF#04-0783).

[0098] The Ag / CdS heterojunction material obtained in Example 1 was analyzed by external-visible absorption spectroscopy, and the results are as follows: Figure 4As shown, the Ag / CdS heterojunction material exhibits a broad absorption peak around 450 nm, which is attributed to the localized plasmon resonance (LSPR) absorption peak of metallic Ag. Compared with the obtained Ag / CdS, the Ag2S / CdS heterojunction used in this embodiment also exhibits certain optical absorption properties between 400-500 nm. The tailing absorption after 550 nm is attributed to the absorption phenomenon of Ag2S.

[0099] The Ag / ZnCdS heterojunction prepared in Example 3 was analyzed by transmission electron microscopy, such as... Figure 2 As shown, the heterojunction exhibits a typical dot-rod structure, where the darker spherical black regions are metallic Ag particles, while the corresponding lighter-colored, bent rod-shaped regions are ternary ZnCdS components. X-ray diffraction analysis was performed on the Ag / ZnCdS heterojunction material obtained in Example 3, and the results are as follows... Figure 5 As shown, the diffraction peaks of the prepared Ag / CdS material correspond one-to-one with the standard cards for wurtzite CdS (PDF#41-1049), wurtzite ZnS (PDF#36-1450), and face-centered cubic Ag (PDF#04-0783).

[0100] The Ag / ZnCdS heterojunction material obtained in Example 3 was subjected to external-visible absorption spectroscopy analysis, and the results are as follows: Figure 6 As shown, the Ag / ZnCdS heterojunction material exhibits a broader LSPR absorption peak around 450 nm. Meanwhile, the Ag2S / ZnCdS used in this embodiment also exhibits relatively strong optical absorption properties between 400-500 nm, while the tailing absorption after 550 nm is also attributed to the absorption phenomenon of Ag2S.

[0101] The Ag / ZnS-1 heterojunction obtained in Example 5 was analyzed by transmission electron microscopy, such as... Figure 7 As shown, the heterojunction exhibits a matchstick-like structure, with the black hemispherical region at one end being Ag hemispherical particles, and the opposite part being ZnS rods. Further particle size statistical analysis based on electron microscopy images revealed that the diameter of the Ag / ZnS-1 heterojunction is 5.4 nm, thus its boundary perimeter can be calculated to be 17.0 nm.

[0102] The Ag / ZnS-3 heterojunction obtained in Example 7 was analyzed by transmission electron microscopy, such as... Figure 8 As shown, the morphology of the heterojunction is similar to that in Example 1. Further particle size statistical analysis based on electron microscope images revealed that the diameter of the Ag / ZnS-3 heterojunction is 10.5 nm, from which its boundary perimeter can be calculated to be 33.0 nm.

[0103] The Ag / ZnS-5 heterojunction obtained in Example 9 was analyzed by transmission electron microscopy, such as... Figure 9 As shown, the morphology of the heterojunction is similar to that in Examples 1 and 3. Further particle size statistical analysis based on electron microscope images revealed that the diameter of the Ag / ZnS-5 heterojunction is 14.8 nm, from which its boundary perimeter can be calculated to be 46.5 nm.

[0104] X-ray diffraction analysis was performed on the different Ag / ZnS heterostructures prepared in Examples 5, 7, and 9 (see...). Figure 10 The spectra were compared with those of wurtzite ZnS (PDF#36-1450) and face-centered cubic Ag (PDF#04-0783) standard cards. Figure 4 The results show that the diffraction peaks of Ag / ZnS heterojunctions with different boundary perimeters correspond one-to-one with the standard peaks of wurtzite ZnS and face-centered cubic Ag. Furthermore, the figure shows that the full width at half maximum (FWHM) of the diffraction peak on the Ag(111) crystal plane at 38.1° decreases with increasing boundary perimeter, reflecting an increase in Ag grain size. This result is consistent with... Figure 7-9 The results are consistent with those obtained by transmission electron microscopy.

[0105] The different Ag / ZnS heterojunctions prepared in Examples 5, 7, and 9 were analyzed by ultraviolet-visible absorption spectroscopy (see [link to example]). Figure 11 The prepared Ag / ZnS heterojunction exhibits unique LSPR optical properties after 350 nm. In contrast, as the boundary perimeter between Ag and ZnS increases, the absorption peak near 400 nm gradually blue-shifts, while the absorption peak at 500 nm gradually red-shifts. These results demonstrate that different boundary perimeters significantly influence the optical absorption properties of the Ag / ZnS heterojunction. Furthermore, compared to the Ag / ZnS heterojunction, the absorption before 350 nm in the Ag₂S / ZnS heterojunction template is attributed to the intrinsic absorption of ZnS, while the absorption after 350 nm is attributed to Ag₂S. Therefore, the optical absorption generated in the prepared Ag / ZnS heterojunction material can be well distinguished, allowing for selective excitation of a specific component and investigation of its application in energy catalytic conversion.

[0106] Based on the optical absorption properties of the different types of metal / sulfide heterojunctions prepared above, Examples 5, 7, and 9 were selected to be excited with LSPR absorption peaks under visible light irradiation to study their plasmonic-induced photocatalytic hydrogen evolution performance. The results are as follows: Figure 12 As shown, Ag / ZnS heterojunctions exhibit different plasmonic-induced photocatalytic hydrogen evolution performances, and their hydrogen evolution performance increases with the increase of the boundary perimeter (see...). Figure 12The hydrogen evolution performance was 60.6 μmol / g / h (17.0 nm), 585.4 μmol / g / h (33.0 nm), and 194.7 μmol / g / h (46.5 nm), respectively. Among them, the Ag / ZnS-3 heterojunction with a boundary perimeter of 33.0 nm showed the best hydrogen evolution performance.

[0107] Example 11: 6 mL of 0.1 M Ag₂S / ZnS heterojunction toluene dispersion, 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated under vacuum to 120 °C and maintained for 30 min with stirring. Nitrogen gas was then introduced, and the mixture was allowed to cool naturally to 60 °C. At this temperature, 1 mL of octadecene solution containing 10% vol n-dodecylthiol and 1 mL of tri-n-octylphosphine were sequentially added to the reaction system. The temperature was raised to 220 °C, and the reaction was allowed to proceed for 10 min. The mixture was then cooled to room temperature, centrifuged, and the solid was collected. The solid was washed twice with a 1:1 mixture of toluene and n-hexane to obtain an epitaxial metal / semiconductor heterojunction, denoted as E-Ag / ZnS-1. E-Ag / ZnS-1 was dispersed in toluene solution and subjected to UV-Vis absorption and transmission electron microscopy.

[0108] Example 12: 6 mL of 0.1 M Ag₂S / ZnS heterojunction toluene dispersion, 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated under vacuum to 100 °C and maintained for 60 min with stirring. Nitrogen gas was then introduced, and the mixture was allowed to cool naturally to 90 °C. At this temperature, 1 mL of octadecene solution containing 5% vol n-dodecylthiol and 0.5 mL of tri-n-octylphosphine were sequentially added to the reaction system. The temperature was raised to 200 °C, and the reaction was carried out for 10 min. After cooling to room temperature, the solid was collected by centrifugation and washed twice with a mixed solution of toluene and n-hexane (volume ratio 1:1) to obtain an epitaxial metal / semiconductor heterojunction, denoted as E-Ag / ZnS-2. E-Ag / ZnS-2 was dispersed in toluene solution and subjected to UV-Vis absorption and transmission electron microscopy.

[0109] Example 13: 6 mL of 0.1 M Ag₂S / ZnS heterojunction toluene dispersion, 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated under vacuum to 110 °C and maintained for 50 min with stirring. Nitrogen gas was then introduced, and the mixture was allowed to cool naturally to 90 °C. At this temperature, 1 mL of octadecene solution containing 30% vol n-dodecyl mercaptan and 0.7 mL of tri-n-octylphosphine were sequentially added to the reaction system. The temperature was raised to 220 °C, and the reaction was carried out for 10 min. After cooling to room temperature, the solid was collected by centrifugation and washed twice with a mixed solution of toluene and n-hexane (volume ratio 1:1) to obtain an epitaxial metal / semiconductor heterojunction, denoted as E-Ag / ZnS-3. E-Ag / ZnS-3 was dispersed in toluene solution and subjected to UV-Vis absorption and transmission electron microscopy.

[0110] Example 14: 6 mL of 0.1 M Ag₂S / ZnS heterojunction toluene dispersion, 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated under vacuum to 120 °C and maintained for 60 min with stirring. Nitrogen gas was then introduced, and the mixture was allowed to cool naturally to 90 °C. At this temperature, 1 mL of octadecene solution containing 10% vol n-dodecylthiol and 2 mL of tri-n-octylphosphine were sequentially added to the reaction system. The temperature was raised to 230 °C, and the reaction was carried out for 30 min. After cooling to room temperature, the solid was collected by centrifugation and washed twice with a mixed solution of toluene and n-hexane (volume ratio 1:1) to obtain an epitaxial metal / semiconductor heterojunction, denoted as E-Ag / ZnS-4. E-Ag / ZnS-4 was dispersed in toluene solution and subjected to UV-Vis absorption and transmission electron microscopy.

[0111] Example 15: 6 mL of 0.1 M Ag₂S / ZnS heterojunction toluene dispersion, 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated under vacuum to 120 °C and maintained for 60 min with stirring. Nitrogen gas was then introduced, and the mixture was allowed to cool naturally to 80 °C. At this temperature, 1 mL of octadecene solution containing 0% vol n-dodecylthiol and 1 mL of tri-n-octylphosphine were sequentially added to the reaction system. The temperature was raised to 200 °C, and the reaction was allowed to proceed for 5 min. The mixture was then cooled to room temperature, centrifuged, and the solid was collected. The solid was washed twice with a mixture of toluene and n-hexane (volume ratio 1:1) to obtain a metal / semiconductor heterojunction, denoted as N-Ag / ZnS-1. N-Ag / ZnS-1 was dispersed in toluene solution and subjected to UV-Vis absorption and transmission electron microscopy.

[0112] Example 16: 6 mL of 0.1 M Ag₂S / ZnS heterojunction toluene dispersion, 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated under vacuum to 130 °C and maintained for 30 min with stirring. Nitrogen gas was then introduced, and the mixture was allowed to cool naturally to 70 °C. At this temperature, 1 mL of octadecene solution containing 0% vol n-dodecylthiol and 0.5 mL of tri-n-octylphosphine were sequentially added to the reaction system. The temperature was raised to 230 °C, and the reaction was carried out for 30 min. After cooling to room temperature, the solid was collected by centrifugation and washed twice with a mixed solution of toluene and n-hexane (volume ratio 1:1) to obtain N-Ag / ZnS₂ heterojunctions. N-Ag / ZnS₂ was dispersed in toluene solution and subjected to UV-Vis absorption and transmission electron microscopy.

[0113] The phase transfer method for the materials is consistent with that described above. Photoreduction performance test of methyl viologen: In a cuvette with a 1 cm optical path, the concentration of the aqueous dispersions of the E-Ag / ZnS-1 and N-Ag / ZnS-2 heterojunctions prepared in Examples 11 and 16 was adjusted to an absorbance of 0.5 at 420 nm. 1 mg of methyl viologen (MV) was added to a 3 mL volume of this solution. 2+ ) and 5 mg sodium sulfite (Na2SO3). The solution was bubbled with argon gas in a glove box for 15 min to remove dissolved oxygen. Under dark conditions, MV 2+ A slower reaction rate occurs between Na₂SO₃ and the solution. The sealed cuvette containing the reaction solution is then placed under a single-wavelength light source at 420 nm (300 W xenon lamp, DT420, 20 nm full width at half maximum, 28 mW / cm²). 2 The reaction rate increases under irradiation. According to methylene viologen (MV +▪ The absorption coefficient of 1.1 × 10⁻⁶ is 1.1 × 10⁻� 4 L mol −1 cm −1 The absorbance difference relative to the zero time point is calculated using parameters such as , and then used to calculate MV. +▪ The concentration of free radicals, the results are shown in [the table]. Figure 21 As shown.

[0114] The experimental results are as follows: Figure 14 These are transmission electron microscope images of E-Ag / ZnS from Embodiment 11 of the present invention, such as... Figure 14 As shown, the obtained E-Ag / ZnS mainly exhibits a one-dimensional rod-shaped heterostructure, with the black region at the end being the Ag domain region and the opposite region being the ZnS nanorods; some of the heterostructures lost the Ag domain region and only retained the ZnS rod-shaped part, which is due to the large lattice stress formed between the Ag particles and the ZnS rods, causing them to separate.

[0115] Figure 16The images are aberration-corrected bright-field scanning transmission electron microscope (BF-STEM) images and corresponding electron diffraction images at the E-Ag / ZnS heterojunction interface in Embodiment 11 of the present invention. In the BF-STEM image, it can be clearly seen that the Ag and ZnS interface has a smooth and orderly connection and the crystal lattice is parallel to each other. Furthermore, through the corresponding diffraction images, it is observed that the diffraction spots of the (220) and (111) crystal planes of Ag are on the same straight line as the diffraction spots of the (110) and (002) crystal planes of ZnS, respectively, that is, the crystal planes are parallel to each other.

[0116] Figure 15 These are transmission electron microscope images of N-Ag / ZnS prepared in Example 15 of this invention, such as... Figure 15 As shown, the obtained N-Ag / ZnS heterojunction also exhibits a one-dimensional rod-like structure, with almost all rod-like structures containing black Ag hemispherical regions. Figure 17 These are high-magnification transmission electron microscope images and corresponding selected area electron diffraction images of N-Ag / ZnS prepared in Example 15 of this invention, such as... Figure 17 As shown, in the high-magnification transmission electron microscope image, it can be clearly observed that the Ag hemisphere is not a single crystal, and the lattice fringes are not parallel to the lattice fringes of the ZnS rod. Furthermore, through selected area electron diffraction, it can be observed that the diffraction spots of the (111) crystal plane of Ag are not on the same straight line as the diffraction spots of the (002) crystal plane of ZnS, that is, the crystal planes are not parallel.

[0117] Figure 18 This is a statistical result diagram of the epitaxial and non-epitaxy interfaces in the E-Ag / ZnS and N-Ag / ZnS heterojunctions prepared in Examples 11 and 15 of this invention, as shown in the figure. Figure 18 As shown, in E-Ag / ZnS heterojunctions with epitaxial interfaces prepared by ligand-assisted chemical transformation, almost all heterojunction interfaces exhibit epitaxial connections; while in N-Ag / ZnS heterojunctions prepared without ligand assistance, the proportion of epitaxially connected interfaces is about 50%, and the proportion of non-epitaxylated interfaces is about 50%.

[0118] Figure 19 These are the X-ray diffraction patterns of the E-Ag / ZnS and N-Ag / ZnS heterojunctions prepared in Examples 11 and 15 of this invention, as shown below. Figure 19 As shown, all diffraction peaks were compared with standard spectra of wurtzite ZnS (PDF#36-1450) and face-centered cubic Ag (PDF#04-0783). From... Figure 19 It can be seen that their diffraction peaks correspond one-to-one with the standard peaks of wurtzite ZnS and face-centered cubic Ag.

[0119] Figure 20These are the UV-Vis absorption spectra of the E-Ag / ZnS and N-Ag / ZnS heterojunctions prepared in Examples 11 and 15 of this invention, as shown below. Figure 20 As shown, they exhibit similar characteristic absorption peaks around 400 nm and 500 nm, respectively. Figure 21 This is a comparison of the photoreduction properties of E-Ag / ZnS and N-Ag / ZnS heterojunctions prepared in Examples 11 and 15 of this invention for methyl viologen, as shown in the figure. Figure 21 As shown, the E-Ag / ZnS heterojunction nanomaterial with a high-yield epitaxial interface prepared in Example 11 exhibits the best performance in reducing methyl viologen, indicating that more hot electrons are transferred to the conduction band of ZnS through the epitaxial interface to participate in the reduction reaction of methyl viologen.

[0120] Comparative Example 1: This comparative example is similar to Example 11, except that 1 mL of an octadecene solution containing 10% vol n-dodecylthiol and 1 mL of tri-n-octylphosphine were first mixed and then injected into the reaction system. Characterization of the obtained product revealed that transmission electron microscopy showed a significant presence of non-epitaxymmetric interface-connected heterostructures, resulting in unsatisfactory performance; furthermore, it may cause the product color to deviate directly from the target product color.

[0121] Comparative Example 2: This comparative example is similar to Example 11, except that the content of n-dodecyl mercaptan is increased to 70% vol. The resulting product was characterized, and transmission electron microscopy images showed an increased degree of separation between the Ag particles and the ZnS rods, as shown in the following figures. Figure 22 As shown.

[0122] Based on the above experimental results, it can be concluded that the present invention utilizes a ligand-assisted chemical conversion method to obtain epitaxial interface metal / semiconductor heterojunction materials with high yield. This method does not require precise control of reaction conditions, is not affected by specific exposed crystal faces of the seed crystal, and has low requirements for reaction kinetics and thermodynamics, thus achieving a breakthrough in constructing metal / semiconductor heterostructures with epitaxial interfaces.

[0123] Example 17 (1) Measure 10 mL of 0.1 M Ag2S / ZnS / CdS / ZnS (n=1) heterojunction toluene dispersion and 10 mL of 0.1 M silver nitrate methanol solution and place them in 50 mL centrifuge tubes. Place them at 0 °C to form a constant temperature uniform dispersion liquid. Then mix the two quickly and shake for 1 min. Centrifuge, take the solid, and wash it twice with toluene and methanol (volume ratio of 1:1). Finally, disperse it with 3 mL of toluene to obtain axially ordered Ag2S / ZnS / Ag2S / ZnS heterojunctions.

[0124] (2) The Ag2S / ZnS / Ag2S / ZnS heterojunction toluene dispersion prepared in (1), 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated to 120 °C under vacuum and maintained for 30 min under stirring. Nitrogen gas was then introduced into the anhydrous and oxygen-free mixture. Then, 1 mL of octadecene solution containing 5% vol n-dodecyl mercaptan and 1 mL of tri-n-octylphosphine solution were added to the solution system in sequence. The mixture was heated to 220 °C under an inert atmosphere and reacted for 1 min. The mixture was then cooled to room temperature and washed twice with toluene and n-hexane to obtain axially ordered Ag / ZnS / Ag / ZnS heterojunctions dispersed in toluene solution. The mixture was then subjected to ultraviolet-visible absorption spectroscopy and transmission electron microscopy.

[0125] Example 18 (1) Measure 0.1 M of axially ordered Ag2S / ZnS / CdS / ZnS heterojunction toluene dispersion (10 mL) and 0.3 M silver nitrate methanol solution (10 mL) and place them in a 50 mL centrifuge tube. Place them at an ambient temperature of 5°C to form a uniformly dispersed liquid at a constant temperature. Then mix the two quickly and shake for 3 min. After centrifugation, wash twice with toluene and methanol (volume ratio of 1:1). Finally, disperse with 3 mL of toluene to obtain axially ordered Ag2S / ZnS / Ag2S / ZnS heterojunction.

[0126] (2) The Ag2S / ZnS / Ag2S / ZnS heterojunction toluene dispersion prepared in (1), 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated to 100 °C under vacuum and maintained for 50 min under stirring. Nitrogen gas was then introduced into the anhydrous and oxygen-free mixture. Then, 1 mL of octadecene solution containing 10% vol n-dodecyl mercaptan and 1 mL of tri-n-octylphosphine solution were added to the solution system in sequence. The mixture was heated to 200 °C under an inert atmosphere and reacted for 5 min. The mixture was then cooled to room temperature and washed twice with toluene and n-hexane to obtain axially ordered Ag / ZnS / Ag / ZnS heterojunctions dispersed in toluene solution. The mixture was then subjected to UV-Vis absorption spectroscopy and transmission electron microscopy.

[0127] Example 19 (1) Measure 0.1 M of axially ordered Ag2S / ZnS / (CdS / ZnS)2 heterojunction toluene dispersion (10 mL) and 0.2 M silver nitrate methanol solution (10 mL) and place them in 50 mL centrifuge tubes. Place them at 0 °C to form a constant temperature uniform dispersion liquid. Then mix the two quickly and shake for 3 min. After centrifugation, wash twice with toluene and methanol (volume ratio of 1:1). Finally, disperse with 3 mL of toluene to obtain axially ordered Ag2S / ZnS / (Ag2S / ZnS)2 heterojunction.

[0128] (2) The Ag2S / ZnS / (Ag2S / ZnS)2 heterojunction toluene dispersion prepared in (1), 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated to 120 °C under vacuum and maintained for 60 min under stirring. Nitrogen gas was then introduced into the anhydrous and oxygen-free mixture. Then, 1 mL of octadecene solution containing 10% vol n-dodecyl mercaptan and 2 mL of tri-n-octylphosphine solution were added to the solution system in sequence. The mixture was heated to 220 °C under an inert atmosphere and reacted for 2 min. The mixture was then cooled to room temperature and washed twice with toluene and n-hexane to obtain axially ordered Ag / ZnS / (Ag / ZnS)2 heterojunctions dispersed in toluene solution. The mixture was then subjected to UV-Vis absorption spectroscopy and transmission electron microscopy.

[0129] Example 20 (1) Measure 0.1 M of axially ordered Ag2S / ZnS / (CdS / ZnS)2 heterojunction toluene dispersion (10 mL) and 0.6 M of silver nitrate methanol solution (10 mL) and place them in a 50 mL centrifuge tube. Place them at an ambient temperature of 10 °C to form a uniformly dispersed liquid at a constant temperature. Then mix the two quickly and shake for 3 min. After centrifugation, wash twice with toluene and methanol (volume ratio of 1:1). Finally, disperse with 3 mL of toluene to obtain axially ordered Ag2S / ZnS / (Ag2S / ZnS)2 heterojunction.

[0130] (2) The Ag2S / ZnS / (Ag2S / ZnS)2 heterojunction toluene dispersion prepared in (1), 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated to 120 °C under vacuum and maintained for 40 min under stirring. Nitrogen gas was then introduced into the anhydrous and oxygen-free mixture. Then, 1 mL of octadecene solution containing 15% vol n-dodecyl mercaptan and 2 mL of tri-n-octylphosphine solution were added to the solution system in sequence. The mixture was heated to 230 °C under an inert atmosphere and reacted for 5 min. The mixture was then cooled to room temperature and washed twice with toluene and n-hexane to obtain axially ordered Ag / ZnS / (Ag / ZnS)2 heterojunctions dispersed in toluene solution. The mixture was then subjected to UV-Vis absorption spectroscopy and transmission electron microscopy.

[0131] Example 21 (1) Measure 0.1 M of axially ordered Ag2S / ZnS / (CdS / ZnS)3 heterojunction toluene dispersion (10 mL) and 0.3 M silver nitrate methanol solution (10 mL) and place them in a 50 mL centrifuge tube. Place them at an ambient temperature of 5°C to form a uniformly dispersed liquid at a constant temperature. Then mix the two quickly and shake for 1 min. After centrifugation, wash twice with toluene and methanol (volume ratio of 1:1). Finally, disperse with 3 mL of toluene to obtain axially ordered Ag2S / ZnS / (Ag2S / ZnS)3 heterojunction.

[0132] (2) The Ag2S / ZnS / (Ag2S / ZnS)3 heterojunction toluene dispersion prepared in (1), 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated to 120 °C under vacuum and maintained for 40 min under stirring. Nitrogen gas was then introduced into the anhydrous and oxygen-free mixture. Then, 1 mL of octadecene solution containing 20% ​​vol n-dodecyl mercaptan and 2 mL of tri-n-octylphosphine solution were added to the solution system in sequence. The mixture was heated to 220 °C under an inert atmosphere and reacted for 3 min. The mixture was then cooled to room temperature and washed twice with toluene and n-hexane to obtain axially ordered Ag / ZnS / (Ag / ZnS)3 heterojunctions dispersed in toluene solution. The mixture was then subjected to UV-Vis absorption spectroscopy and transmission electron microscopy.

[0133] Example 22 (1) 0.1 M of axially ordered Ag2S / ZnS / (CdS / ZnS)3 heterojunction toluene dispersion (10 mL) and 1 M silver nitrate methanol solution (10 mL) were respectively placed in 50 mL centrifuge tubes and placed at an ambient temperature of 8°C to form a constant temperature uniform dispersion liquid. Then the two were quickly mixed and shaken for 3 min. After centrifugation, the mixture was washed twice with toluene and methanol (volume ratio of 1:1). Finally, axially ordered Ag2S / ZnS / (Ag2S / ZnS)3 heterojunctions were dispersed with 3 mL of toluene.

[0134] (2) The Ag2S / ZnS / (Ag2S / ZnS)3 heterojunction toluene dispersion prepared in (1), 6 mL of octadecene, and 2 mL of oleylamine were added to a 50 mL three-necked flask. The mixture was heated to 120 °C under vacuum and maintained for 50 min under stirring. Nitrogen gas was then introduced into the anhydrous and oxygen-free mixture. Then, 1 mL of octadecene solution containing 25% vol n-dodecyl mercaptan and 2 mL of tri-n-octylphosphine solution were added to the solution system in sequence. The mixture was heated to 240 °C under an inert atmosphere and reacted for 3 min. The mixture was then cooled to room temperature and washed twice with toluene and n-hexane to obtain axially ordered Ag / ZnS / (Ag / ZnS)3 heterojunctions dispersed in toluene solution. The mixture was then subjected to UV-Vis absorption spectroscopy and transmission electron microscopy.

[0135] The phase transfer method is consistent with that described above. Device fabrication: First, an axially ordered Ag-ZnS heterojunction dispersion modified with 3-mercaptopropionic acid was carefully layered onto an N-methylformamide surface in chloroform (0.1 mg / mL) after precise volume measurement. Through this interfacial self-assembly process, a centimeter-scale thin film spontaneously formed at the gas-liquid interface after approximately 1 hour. The resulting film was then transferred to a pre-patterned electrode substrate via direct contact. Residual N-methylformamide solvent was carefully removed using absorbent paper, and the device was then thermally annealed at 120°C under vacuum for 2 hours to ensure proper film adhesion and electrical contact formation.

[0136] The experimental results are as follows: The axially ordered Ag / ZnS / Ag / ZnS heterojunction obtained in Example 17 was analyzed by transmission electron microscopy, see [link to relevant documentation]. Figure 23 The darker, granular regions are Ag domains, while the lighter, rod-shaped regions are ZnS, arranged in an ordered pattern of Ag-ZnS-Ag-ZnS. Further particle size analysis based on electron microscopy images revealed that the diameter of the Ag / ZnS heterojunction is approximately 11.0 nm.

[0137] The axially ordered Ag / ZnS / (Ag / ZnS)2 heterojunction obtained in Example 19 was analyzed by transmission electron microscopy. (See [link to relevant documentation]) Figure 24 The nanorods exhibit three darker Ag particle regions and three lighter ZnS rod-shaped regions, arranged in an ordered manner of Ag-ZnS-Ag-ZnS-Ag-ZnS. Further particle size analysis based on electron microscopy images revealed that the diameter of the Ag / ZnS heterojunction is approximately 10.5 nm.

[0138] The axially ordered Ag / ZnS / (Ag / ZnS)3 heterojunction obtained in Example 21 was analyzed by transmission electron microscopy. (See [link to relevant documentation]) Figure 25 The nanorods exhibit four darker Ag particle domains and four lighter ZnS rod-shaped regions, arranged axially in an orderly manner in an Ag-ZnS-Ag-ZnS-Ag-ZnS-Ag-ZnS pattern. Further particle size statistical analysis based on electron microscopy images revealed that the diameter of the Ag / ZnS heterojunction is approximately 11.3 nm.

[0139] X-ray diffraction analysis was performed on the axially ordered Ag / ZnS heterostructures with different number of segments prepared in Examples 17, 19, and 21 (see [reference]). Figure 26 The spectra were compared with those of wurtzite ZnS (PDF#36-1450) and face-centered cubic Ag (PDF#04-0783) standard plates. Figure 26It can be seen that the diffraction peaks of the ordered Ag / ZnS heterojunctions in different axes correspond one-to-one with the standard peaks of wurtzite ZnS and face-centered cubic Ag.

[0140] The axially ordered Ag / ZnS heterojunctions with different numbers of segments prepared in Examples 17, 19, and 21 were analyzed by ultraviolet-visible absorption spectroscopy (see [reference]). Figure 27 As the number of Ag segments increases, the UV-Vis absorption intensity gradually increases, accompanied by a redshift in the absorption range.

[0141] The axially ordered Ag / ZnS heterojunctions with different numbers of segments obtained in Examples 17, 19, and 21 were fabricated into photodetectors and their photoresponse was tested. (See [link to relevant documentation]). Figure 28 At a wavelength of 410 nm and an intensity of 30 mW / cm 2 When heterojunction devices are irradiated with colored light, the light response intensity increases with the increase of the number of Ag segments.

[0142] Comparative Example 3: This comparative example differs from Example 21 in that, after purging nitrogen gas, 2 mL of a solution containing tri-n-octylphosphine was added to the solution system; the remaining steps were the same. Transmission electron microscopy (TEM) was performed on the resulting axially ordered Ag / ZnS / (Ag / ZnS)3 heterojunction. The results showed that the rod-shaped regions in the heterojunction contained a large number of randomly distributed small particles, which affected the formation of the target product.

[0143] Comparative Example 4: This comparative example differs from Example 21 in that, after purging with nitrogen, 2 mL of a solution containing tri-n-octylphosphine was added to the solution system, and the reaction was stopped at 220°C for 15 min under an inert atmosphere. The remaining steps were the same. The axially ordered Ag / ZnS / (Ag / ZnS)3 heterojunction was tested using transmission electron microscopy, and the results are as follows... Figure 29 As shown, the rod-shaped region in the heterojunction still contains some randomly distributed small particles, which cannot be eliminated by extending the reaction time, thus causing the product to deviate from the configuration of the target product.

[0144] Comparative Example 5: This comparative example differs from Example 21 in that the reaction was stopped at 220°C for 15 minutes under an inert atmosphere; the remaining steps were the same. The axially ordered Ag / ZnS / (Ag / ZnS)3 heterojunction was subjected to transmission electron microscopy (TEM), and the results are as follows: Figure 30 As shown, some Ag segments in the heterojunction begin to disappear, accompanied by the generation of Ag spherical particle byproducts, causing the final result to deviate from the target product.

[0145] Comparative Example 6: This comparative example differs from Example 21 in that, in step (2), the concentration of the octadecene solution of n-dodecyl mercaptan is 40% vol, while the other steps are the same. The axially ordered Ag / ZnS / (Ag / ZnS)3 heterojunction was tested using transmission electron microscopy, and the results were similar. Figure 30 Ag detaches and forms spherical particles, resulting in a deviation in the product configuration.

[0146] Based on the above experimental results, it can be concluded that the present invention utilizes semiconductor / semiconductor heterojunctions with different axial orders as templates to obtain metal / semiconductor heterojunction materials with good axial order step by step through cation exchange and chemical transformation methods, and has made a breakthrough in constructing a novel metal / semiconductor heterostructure.

Claims

1. A method for preparing an axially ordered metal / semiconductor heterojunction, characterized in that, Includes the following steps: (1) Disperse the axially ordered semiconductor / semiconductor heterojunction in a nonpolar organic solvent, form a mixture with unsaturated fatty olefins and unsaturated fatty amines, and heat to remove the nonpolar organic solvent, oxygen and water; (2) Mix the mixture obtained in step (1) with thiol and organophosphorus, heat to 200~240℃, react for 1~5 minutes, cool, take the solid, and obtain a metal / semiconductor heterojunction.

2. The method for preparing an axially ordered metal / semiconductor heterojunction according to claim 1, characterized in that, The axially ordered semiconductor / semiconductor heterojunction is an Ag₂S / ZnS / (Ag₂S / ZnS) structure with a one-dimensional nanowire structure. n The heterojunction is a metal / semiconductor heterojunction of Ag / ZnS / (Ag / ZnS). n Heterogeneous junction, n≥1.

3. The method for preparing an axially ordered metal / semiconductor heterojunction according to claim 2, characterized in that, In step (2), when 1≤n≤3, the molar ratio of semiconductor / semiconductor heterojunction, thiol, and organophosphorus is 1:0.05~1.6:2~5, and the proportion of thiol and organophosphorus added increases with the increase of n.

4. The method for preparing an axially ordered metal / semiconductor heterojunction according to claim 3, characterized in that, For n=1, the molar ratio of semiconductor / semiconductor heterojunction, thiol, and organophosphorus is 1: 0.12 ~ 0.45: 2 ~ 3; for n=2, the molar ratio of semiconductor / semiconductor heterojunction, thiol, and organophosphorus is 1: 0.4 ~ 0.75: 3 ~ 5; for n=3, the molar ratio of semiconductor / semiconductor heterojunction, thiol, and organophosphorus is 1: 0.8 ~ 1.1: 3 ~ 5.

5. The method for preparing an axially ordered metal / semiconductor heterojunction according to claim 3 or 4, characterized in that, In step (2), after the thiol and unsaturated fatty olefin form a solution, it is added to the mixture. The volume concentration of the thiol in the solution formed by the thiol and unsaturated fatty olefin is ≤25%vol.

6. The method for preparing an axially ordered metal / semiconductor heterojunction according to claim 1, characterized in that, In step (1), the molar ratio of semiconductor / semiconductor heterojunction and unsaturated aliphatic amine is 1: 1.1~7.

7. The method for preparing an axially ordered metal / semiconductor heterojunction according to claim 1, characterized in that, In step (1), the nonpolar organic solvent is toluene and / or n-hexane, the unsaturated fatty olefin is 1-octadecene, the unsaturated fatty amine is oleylamine, and the heating conditions are: under vacuum, the mixture is heated to 100~120℃ and maintained for 30~60 minutes. In step (1), the organophosphorus is tri-n-octylphosphine, and the thiol is n-dodecyl mercaptan.

8. The method for preparing an axially ordered metal / semiconductor heterojunction according to claim 1, characterized in that, In step (2), the method for obtaining the axially ordered semiconductor / semiconductor heterojunction is as follows: The axially ordered semiconductor / semiconductor heterojunction Ag2S / ZnS / (CdS / ZnS) is formed. n Equal volumes of toluene dispersion and silver nitrate alcohol solution were mixed and subjected to a cation exchange reaction at 0–10 °C to obtain Ag₂S / ZnS / (AgS / ZnS). n The concentration of the silver nitrate alcohol solution is 0.1~1 mol / L, and the axially ordered semiconductor / semiconductor heterojunction Ag2S / ZnS / (CdS / ZnS) is... n The concentration of the dispersion is not greater than that of the silver nitrate alcohol solution, and the duration of the cation exchange reaction is 0.5 to 5 minutes.

9. An axially ordered metal / semiconductor heterojunction, characterized in that, It is prepared by the preparation method of any one of claims 1 to 8 for axially ordered metal / semiconductor heterojunction.

10. The application of the axially ordered metal / semiconductor heterojunction of claim 9 in photodetector devices.

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