Core-shell nanocrystal of metal-amorphous structure chalcogenide compound, and preparation method and application thereof

Abstract

The present application relates to the field of chemical synthetic materials and catalysis, and particularly relates to a metal-amorphous structure chalcogenide core-shell nanocrystal and a preparation method and application thereof.The preparation method comprises the following steps: (1) synthesizing Au nanorods through a seed growth method; (2) coating silver on the surface of the Au, and epitaxially growing a silver shell layer nanocrystal; and (3) sulfidizing the silver shell layer nanocrystal, and performing hydrothermal cation exchange to obtain a core-shell structure nanocrystal.In the metal-amorphous structure chalcogenide core-shell nanocrystal, the amorphous surface to a certain extent is conducive to adsorbing reaction substrates, and promotes the progress of the photocatalytic carbon dioxide reduction reaction.The metal-amorphous structure chalcogenide core-shell nanocrystal has excellent gas-solid phase photocatalytic carbon dioxide reduction performance, and can achieve good effects without a photosensitizer and a sacrificial agent.

Description

Technical Field

[0001] This invention relates to the fields of chemical synthesis materials and catalysis, and particularly to a core-shell nanocrystal of a metal-amorphous chalcogenide compound, its preparation method, and its application. Background Technology

[0002] Nanomaterials have attracted widespread attention from the scientific community due to their unique properties. In recent years, numerous scholars both domestically and internationally have made significant progress in the controlled synthesis of liquid-phase nanocrystals to meet different performance requirements. Precise control over the size and morphology of nanocrystals has been largely achieved.

[0003] Noble metal-semiconductor core-shell nanocrystals, due to the localized plasmon resonance effect of noble metals combined with the unique properties of nanocrystals, can enhance light absorption while effectively increasing the concentration of photogenerated carriers in the semiconductor shell, improving electron-hole separation efficiency. The amorphous material also facilitates substrate adsorption, promoting catalytic reactions. However, due to the large lattice mismatch between the noble metal and the semiconductor, core-shell nanocrystals synthesized by traditional methods have numerous defects. These intercomponent defects can lead to electron annihilation, inhibiting their optoelectronic applications.

[0004] Chinese patent application CN104437549A discloses a novel high-efficiency photocatalyst for water splitting with enhanced surface plasmon resonance. The catalyst consists of well-crystallized Au particles as the core and CdX (X = S, Se) semiconductors as the shell, exhibiting high hydrogen production performance. However, the catalyst of this invention lacks an amorphous surface capable of adsorbing reactants and does not provide more reaction sites.

[0005] Therefore, it is necessary to design a core-shell nanocrystal of a metal-amorphous chalcogenide compound that simultaneously possesses a high crystallinity interface and an amorphous surface to solve the above problems. Summary of the Invention

[0006] Based on the limitations of the prior art, the purpose of this invention is to provide a core-shell nanocrystal of a metal-amorphous chalcogenide compound that simultaneously possesses a high crystalline interface and an amorphous surface, exhibiting excellent photogenerated electron-hole separation efficiency and substrate adsorption performance, thereby achieving high gas-solid phase photocatalytic carbon dioxide reduction efficiency.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] A method for preparing core-shell nanocrystals of a metal-amorphous chalcogenide compound includes the following steps:

[0009] (1) Synthesizing Au nanorods by seed growth method;

[0010] (2) Silver was coated on the surface of Au nanorods, and silver shell nanocrystals were epitaxially grown to obtain Au@Ag nanorods;

[0011] (3) Sulfide Au@Ag nanorods to obtain Au@Ag2S nanorods;

[0012] (4) Au@Ag2S nanorods were dispersed in a hexadecyltrimethylammonium bromide solution, and Zn(NO3)2 aqueous solution and triphenylphosphine toluene solution were added in sequence to carry out a hydrothermal reaction. After cooling, the mixture was allowed to stand to obtain amorphous surface structure Au@ZnS core-shell nanocrystals.

[0013] Preferably, step (1) includes:

[0014] Step (1-1): Disperse HAuCl4 in an aqueous solution of hexadecyltrimethylammonium bromide, add an aqueous solution of NaBH4, and prepare a seed solution;

[0015] Steps (1-2): Disperse HAuCl4 in a mixed aqueous solution of hexadecyltrimethylammonium bromide and dodecyldimethylbenzylammonium chloride, and add AgNO3 and ascorbic acid aqueous solution in sequence to prepare the growth solution;

[0016] Steps (1-3): Add the seed solution to the growth solution for aging, and centrifuge to obtain Au nanorods.

[0017] More preferably, in step (1-1), the molar ratio of HAuCl4, hexadecyltrimethylammonium bromide, and NaBH4 is 1:(380-420):(2.3-2.5);

[0018] More preferably, in step (1-2), the molar ratio of HAuCl4, hexadecyltrimethylammonium bromide, dodecyldimethylbenzylammonium chloride, AgNO3, and ascorbic acid is 1:(190-250):(190-290):(0.1-0.3):(1-1.5).

[0019] More preferably, in steps (1-3), the volume ratio of seed solution to growth solution is 1:(850-1300), and the aging time is 8-16 hours.

[0020] Preferably, step (2) includes:

[0021] Au nanorods were dispersed in a hexadecyltrimethylammonium bromide solution, and AgNO3, ascorbic acid, and NaOH were added sequentially under heating conditions to obtain Au@Ag nanorods. The heating temperature was 30–40 °C, and the molar ratio of Au nanorods, hexadecyltrimethylammonium bromide, AgNO3, ascorbic acid, and NaOH was 1:(1–1.5):(0.001–0.003):(0.4–0.6):(0.4–0.6).

[0022] Preferably, step (3) includes:

[0023] Au@Ag nanorods were dispersed in water, and an aqueous sulfur precursor was added to obtain Au@Ag2S nanorods.

[0024] The aqueous sulfur precursor is prepared by reacting sulfur powder and sodium sulfide aqueous solution under hydrothermal conditions.

[0025] More preferably, the volume ratio of the Au@Ag nanorods to the aqueous sulfur precursor is 1:(0.0007~0.015);

[0026] Selectively, when the volume ratio of Au@Ag nanorods to aqueous sulfur precursor is 1:(0.0007~0.003), core-shell nanocrystals with partially hollow structures are obtained, with a cavity volume ratio of 5-40%; when the volume ratio of Au@Ag nanorods to aqueous sulfur precursor is 1:(0.003~0.015), core-shell nanocrystals with a dense structure and a void ratio of less than 5% are obtained.

[0027] Preferably, in step (4), the hydrothermal reaction temperature is 60-80℃; the settling time is 10-36h;

[0028] The molar ratio of Au@Ag2S nanorods, hexadecyltrimethylammonium bromide, Zn(NO3)2, and triphenylphosphine is 1:(0.5-1.5):(0.1-0.5):(0.2-0.6).

[0029] In this invention, a small amount of sulfur source is added to the hollow structure, causing partial sulfidation of the silver shell layer of Au@Ag. This silver shell layer is then etched away during the subsequent hydrothermal reaction, resulting in the formation of the hollow structure. Adding an excessive amount of sulfur source completely sulfidates the Ag layer, resulting in a dense core-shell structure. The addition of an aqueous sulfur precursor in this invention partially or completely transforms the Ag layer into a sulfidated silver shell layer, providing a basis for subsequent ion exchange reactions. Furthermore, the degree of core-shell structure can be controlled by adjusting the amount of sulfur source.

[0030] This invention addresses the issue of amorphous surface control by allowing the hydrothermal reaction to stand. Products obtained directly without standing are fully crystalline components without an amorphous shell. After standing, the interaction between various ligands in the reactants leads to a certain degree of amorphization of the product surface (generally accounting for 10-50%). This amorphous surface is beneficial for substrate adsorption and promotes catalytic reaction. Furthermore, this process does not affect the crystallization interface between the two components and also has a highly crystalline interface, which is conducive to electron transport.

[0031] The core-shell nanocrystals obtained by this invention have a partially hollow structure, meaning there is a certain gap between the shell layer and the central gold rod. Generally, the gold rod occupies approximately 60-95% of the total space inside the shell. When the core-shell nanocrystals obtained by this invention have a dense structure, there is no gap between the shell layer and the central gold rod.

[0032] The present invention further provides a core-shell nanocrystal of a metal-amorphous chalcogenide compound, which is prepared by the above-described preparation method.

[0033] The present invention also provides an application of the core-shell nanocrystals of the aforementioned metal-amorphous chalcogenide compound in photocatalytic carbon dioxide reduction.

[0034] More specifically, the present invention provides a method for preparing core-shell nanocrystals of metal-amorphous chalcogenides that simultaneously possess a high crystallinity interface and an amorphous surface, wherein the core-shell nanocrystals of the metal-amorphous chalcogenides are Au@ZnS nanorods.

[0035] In this invention, the Au@ZnS nanorods are prepared by the following method:

[0036] (1) Disperse HAuCl4 (chloroauric acid) in CTAB (hexadecyltrimethylammonium bromide) aqueous solution, add NaBH4 (sodium borohydride) ice aqueous solution and age to prepare seed solution;

[0037] Add HAuCl4 to a mixed solution of CTAB and BDAC (dodecyl dimethyl benzyl ammonium chloride), then add AgNO3 (silver nitrate) solution, stir well, and add AA (ascorbic acid) to prepare the growth solution;

[0038] The seed solution was added to the growth solution and aged for 12 hours. The precipitate obtained after centrifugation was Au nanorods.

[0039] (2) Au nanorods were dispersed in CTAB solution, and AgNO3, AA and NaOH (sodium hydroxide) were added sequentially under heating and stirring. After centrifugation, the precipitate was Au@Ag nanorods.

[0040] (3) Disperse Au@Ag nanorods in water, add aqueous sulfur precursor, shake well, let stand at room temperature, and centrifuge to obtain Au@Ag2S nanorods.

[0041] (4) Au@Ag2S nanorods were dispersed in CTAB solution, and Zn(NO3)2 (zinc nitrate) aqueous solution and TPP (triphenylphosphine) toluene solution were added sequentially with stirring at room temperature. The hydrothermal reaction was carried out for 2 hours. After cooling, the mixture was allowed to stand for 24 hours and then centrifuged to obtain Au@ZnS core-shell nanocrystals with a high crystallinity interface and a partially amorphous surface.

[0042] Preferably, in step (1), the molar ratio of HAuCl4, CTAB, and NaBH4 is 1:400:2.4.

[0043] Preferably, in step (1), the molar ratio of HAuCl4, CTAB, BDAC, AgNO3, and AA is 1:200:250:(0.1~0.3):(1~1.5).

[0044] Preferably, in step (1), the volume ratio of seed solution to growth solution is 1:1026.

[0045] Preferably, in step (2), the heating temperature is 36°C, and the molar ratio of Au nanorods, CTAB, AgNO3, AA, and NaOH is 1:1:(0.001~0.003):(0.4~0.6):(0.4~0.6).

[0046] Preferably, in step (3), when the volume ratio of Au@Ag nanorods to aqueous sulfur precursor is 1:(0.0007~0.003), core-shell nanocrystals with partially hollow structures are obtained, with a cavity volume ratio of 5-40%; when the volume ratio of Au@Ag nanorods to aqueous sulfur precursor is 1:(0.003~0.015), core-shell nanocrystals with a dense structure and a void ratio of less than 5% are obtained.

[0047] Preferably, in step (4), the hydrothermal temperature is 80℃, the reaction time is 2 hours, the standing time is 24 hours, and the molar ratio of Au@Ag2S nanorods, CTAB, Zn(NO3)2, and TPP is 1:(0.5~1.5):(0.1~0.5):(0.2~0.6).

[0048] Compared with the prior art, the beneficial effects of the present invention are:

[0049] (1) This invention provides Au@ZnS nanorods formed from core-shell nanocrystals of amorphous chalcogenides. Among them, the Au nanorods have a plasmon resonance effect that can effectively enhance light absorption, and the atomic-level heterogeneous interface between highly crystalline components is conducive to the separation of photogenerated electrons and holes.

[0050] (2) In the core-shell nanocrystals of the metal-amorphous chalcogenide compound described in this invention, a certain degree of amorphous surface is beneficial for adsorbing reaction substrates and promoting the photocatalytic carbon dioxide reduction reaction. Its gas-solid phase photocatalytic carbon dioxide reduction performance is excellent, achieving good results without the need for photosensitizers and sacrificial agents.

[0051] (3) The metal-amorphous chalcogenide core-shell nanocrystals prepared by this invention are not limited by large lattice mismatch, and the resulting metal-amorphous chalcogenide core-shell nanocrystals simultaneously possess high crystalline composition and a certain degree of amorphous surface. The introduction of Au nanorods can improve the light absorption performance of the nanocrystals, and the presence of cavities not only increases light refraction but also provides a micro-reaction chamber for the catalytic reaction. The amorphous layer on the surface of the outer ZnS shell adsorbs carbon dioxide, exhibiting better photocatalytic carbon dioxide reduction performance. Attached Figure Description

[0052] Figure 1 This is a schematic diagram illustrating the synthesis of a core-shell nanocrystal of a metal-amorphous chalcogenide compound according to the present invention.

[0053] Figure 2 This is a transmission electron microscope (TEM) image of hollow core-shell structured Au@ZnS nanorods from Example 1.

[0054] Figure 3 This is a transmission electron microscope (TEM) image of dense core-shell structured Au@ZnS nanorods from Example 2.

[0055] Figure 4 Transmission electron microscopy image of Au@ZnS nanorods with a partially hollow core-shell structure and a high crystallinity interface, as shown in Comparative Example 1.

[0056] Figure 5a This is a field emission transmission electron microscope (FET) image of Au@ZnS nanorods with a partially hollow core-shell structure and amorphous surface, which have a high crystallinity interface and are described in Example 1. Figure 5b for Figure 5a Enlarged view of the surface area within the red frame and the interface area within the blue frame;

[0057] Figure 6a This is a field emission transmission electron microscope image of dense core-shell structured nanocrystals with a highly crystalline interface and an amorphous surface, as shown in Example 2. Figure 6b for Figure 6a Enlarged view of the interface section within the red box; Figure 6c Transmission electron microscopy image of the surface portion of dense core-shell nanocrystals;

[0058] Figure 7a The field emission transmission electron microscope image of partially hollow core-shell structured nanocrystals with a highly crystalline interface in Comparative Example 1 is shown. Figure 7b for Figure 7a Enlarged view of the surface portion within the red box;

[0059] Figure 8a The photoelectron spectra of the Au-4f orbitals in Embodiment 1 and Comparative Example 1 of this invention are shown below. Figure 8b The Zn-2p orbital photoelectron spectra of Embodiment 1 and Comparative Example 1 of the present invention are shown below. Figure 8c The photoelectron spectra of the S-2p orbitals in Embodiment 1 and Comparative Example 1 of this invention are shown below.

[0060] Figure 9 The graphs show the gas-solid phase photocatalytic carbon dioxide reduction performance of Examples 1, 2 and Comparative Example 1 of this invention.

[0061] Figure 10 This refers to the stability of gas-solid phase photocatalytic carbon dioxide reduction in Example 1 of the present invention. Detailed Implementation

[0062] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0063] Example 1:

[0064] A method for preparing partially hollow core-shell nanocrystals of a metal-amorphous chalcogenide compound, such as... Figure 1 As shown, it includes the following steps:

[0065] The S1 seed growth method was used to synthesize Au nanorods, and the specific steps are as follows:

[0066] S11 0.3644g CTAB was dispersed in 10mL of water and stirred at room temperature. 25μL of 0.1M HAuCl4 aqueous solution was added, followed by 60μL of 0.1M NaBH4 ice aqueous solution. The mixture was allowed to stand for 1h to obtain the seed solution.

[0067] S12 dispersed 3.6436g CTAB and 4.9521g BDAC into 100mL of water, added 0.5mL of 0.1M HAuCl4 aqueous solution, then added 1mL of 0.01M AgNO3 aqueous solution, stirred evenly, and added 560μL of 0.1MAA to prepare the growth solution.

[0068] S13 added 100 μL of seed solution to the growth medium and let it stand for 12 h. The precipitate obtained after centrifugation is Au nanorods.

[0069] S2 epitaxial growth synthesis of Au@Ag core-shell nanorods:

[0070] S21 redispersed the obtained Au nanorods (1 mmol) in 10 mL of 0.1 M CTAB aqueous solution, with an absorbance of approximately 1;

[0071] Under the conditions of heating and stirring in a 36℃ water bath, add 200μL of 0.01M AgNO3, 5mL of 0.1M AA, and 4-5mL of 0.1M NaOH in sequence. After centrifugation, the precipitate is Au@Ag nanorods.

[0072] Preparation of S3 aqueous sulfur precursor

[0073] S31 Weigh 32mg of S powder and add 11.2mL of 50mM Na2S aqueous solution;

[0074] S32 was ultrasonicated until it turned bright yellow, then transferred to a 20mL reactor and reacted at 80℃ for 16 hours.

[0075] Preparation of S4 Au@ZnS nanorods

[0076] S41 Au@Ag core-shell nanorods were dispersed in 10 ml of water, 10 μl of aqueous sulfur precursor was added, the mixture was shaken at room temperature and allowed to stand for 5 min, and then centrifuged to obtain Au@Ag@Ag2S nanorods.

[0077] Au@Ag@Ag2S nanorods (1 mmol) obtained from S42 were dispersed in 10 mL of 50 mM CTAB aqueous solution, and 1 mL of 30 mg / mL Zn(NO3)2 aqueous solution and 250 μL of toluene solution containing 75 mg TPP were added with stirring at room temperature.

[0078] The mixed solution obtained from S43 was transferred into a reactor and subjected to hydrothermal reaction at 80°C for 2 hours.

[0079] After S44 was cooled and allowed to stand for 24 hours, it was centrifuged at 8000 r / min for 15 min to obtain partially hollow core-shell structured nanocrystals with both highly crystalline interfaces and amorphous surfaces; such as Figure 1 , 2 As shown in 5a and 5b. Figure 1 The diagram shows the preparation method. From top to bottom, Au@ZnS consists of hollow core-shell nanocrystals with amorphous surfaces, hollow core-shell nanocrystals with highly crystalline interfaces, and dense core-shell nanocrystals with amorphous surfaces. Figure 2 The image shows a low-resolution transmission electron microscope image of hollow Au@ZnS core-shell structured nanocrystals with amorphous surfaces, indicating that they are uniformly dispersed core-shell structured nanorods with partial cavities, and the cavities account for 10% to 50% of the volume of the core structure. Figure 5a Image 5b is a field emission transmission electron microscope image of hollow Au@ZnS core-shell nanocrystals with an amorphous surface. Figure 5a This indicates that the sample has good crystallinity. Further magnification of the local interface (blue) and surface (red) revealed... Figure 5bThis indicates that the core-shell structure has a clear heterogeneous interface, with high crystallinity of gold rods and ZnS at the interface. Furthermore, the hollow Au@ZnS core-shell nanocrystals have a certain amorphous surface, as indicated by the arrow, with the amorphous surface accounting for 10% to 30% of the shell area.

[0080] Example 2:

[0081] A dense core-shell structured nanocrystal of a metal-amorphous chalcogenide compound, differing from Example 1 in that 100 μL of an aqueous sulfur precursor is added; otherwise, it is the same as Example 1 and will not be repeated here. Figure 3 , 6a As shown in 6b and 6c. Figure 3 The image shows a low-resolution transmission electron microscope image of dense Au@ZnS core-shell nanocrystals with an amorphous surface, indicating that they are uniformly dispersed core-shell nanorods with no obvious cavity between the Au core and the ZnS shell. Figure 6a , 6b Image 6c is a field emission transmission electron microscope image of dense Au@ZnS core-shell nanocrystals with an amorphous surface. Figure 6a This indicates that the Au core and ZnS shell are in close contact, forming a dense core-shell structure of nanocrystals; Figure 6b for Figure 6a The magnified view of the area within the red box shows that the sample is well-crystallized; Figure 6c This is a magnified view of the sample surface. The area between the red and yellow dashed lines represents the amorphous part of the surface, which accounts for more than 30% of the total area.

[0082] Comparative Example 1:

[0083] A partially hollow core-shell structured nanocrystal with a highly crystalline surface interface is described. The difference between this and Example 1 is that the nanocrystals are centrifuged immediately after cooling following the hydrothermal reaction; otherwise, they are the same as in Example 1 and will not be repeated here. Figure 4 , 7a As shown in 7b. Figure 4 The image shows a low-resolution transmission electron microscope image of hollow Au@ZnS core-shell structured nanocrystals with a high crystallinity interface, indicating that they are uniformly dispersed core-shell structured nanorods with partial cavities, and the volume ratio of cavities to the core structure is 10-50%. Figure 7a Image 7b is a field emission transmission electron microscope image of hollow Au@ZnS core-shell nanocrystals with a highly crystalline surface interface, indicating that the sample is composed of fully crystalline components and has no amorphous parts on the surface.

[0084] The morphology and gas-solid phase photocatalytic carbon dioxide reduction performance of Examples 1, 2, and Comparative Example 1 were characterized as follows:

[0085] (1) Morphological characterization: Samples were dropped onto a 200-mesh carbon support film and observed using a transmission electron microscope, such as... Figure 2-4 As shown in 6a, 6b, 6c, 7a, and 7b, the samples are uniformly dispersed core-shell nanorods with different structural features.

[0086] The nanocrystals in Example 1 of this invention are uniformly dispersed core-shell nanocrystals with a certain hollow cavity. They have a highly crystalline Au core and a ZnS shell, and the outermost layer has a portion of an amorphous morphology.

[0087] In Example 2, an excess of sulfur precursor was added to completely sulfide the Ag layer, resulting in a fully core-shell nanocrystal that does not have cavities.

[0088] In Comparative Example 1, the hydrothermal reaction was not allowed to stand at room temperature afterward. Although this did not have a significant impact on the overall morphology, no amorphous surface morphology was formed.

[0089] (2) Photoelectron spectroscopy (PES) testing: PES testing was performed on partially hollow core-shell nanocrystals and partially hollow core-shell nanocrystals without amorphous surfaces in metal-amorphous chalcogenide compounds. 0.5–1 mL of colloidal nanocrystals were dropped onto a glass substrate, dried on a hot stage at 70°C, and then tested. Based on the spectra of Example 1 and Comparative Example 1, it can be seen that the product consists of Au, Zn, and S. Furthermore, the Zn 2p orbital spectrum of Example 1 shows a distinct amorphous peak, while Comparative Example 1 only shows a Zn peak. 2+ The peaks demonstrate that controlling the post-reaction treatment time can effectively regulate the formation of amorphous morphologies on the surface, such as... Figure 8a , 8b 8c.

[0090] (3) Gas-solid phase photocatalytic carbon dioxide reduction performance test: The photocatalytic carbon dioxide reduction performance of the core-shell nanocrystals of the metal-amorphous chalcogenide compound described in this invention was tested. 2 mg of Au@ZnS nanorods were coated onto a quartz fiber membrane. 3 mL of water was added to the reaction cell, and carbon dioxide was repeatedly pumped in and out three times. Finally, carbon dioxide was introduced to 40 kPa, and the mixture was irradiated with a xenon lamp source with a >420 nm filter. Example 2 and Comparative Example 1 were tested under the same conditions. Figure 9-10 It can be seen that Example 1 exhibits the best photocatalytic performance, with a CO yield of 112.09 μmol / g / h, which is far superior to the dense core-shell nanocrystals with an amorphous surface area of ​​>30% and no cavities (Example 2) and the hollow core-shell nanocrystals without an amorphous surface (Comparative Example 1). Furthermore, it demonstrates good stability, exhibiting stable photocatalytic carbon dioxide reduction performance even after four cycles.

[0091] This invention synthesizes gold nanorods via a seed growth method, then coats the surface of the gold nanorods with silver to obtain gold-coated silver core-shell nanocrystals. Subsequently, the silver shell is partially or completely sulfided, followed by a cation exchange reaction. The sulfided silver shell is topologically transformed into zinc sulfide, while the unsulfided silver shell is etched to form cavities, resulting in partially hollow or dense core-shell nanocrystals with high crystalline composition. By extending the post-processing time, nanocrystals with a certain degree of amorphous surface are obtained. Through the above method, the metal-amorphous chalcogenide core-shell nanocrystals obtained by this invention can effectively promote photogenerated electron-hole separation and facilitate substrate adsorption, thereby improving photocatalytic efficiency. They exhibit excellent gas-solid phase photocatalytic carbon dioxide reduction performance, demonstrating high reaction efficiency and selectivity.

[0092] The upper and lower limits of the process parameters (such as temperature, time, etc.) and the range values ​​of the present invention can all achieve the method, and examples are not listed here.

[0093] All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing core-shell nanocrystals of a metal-amorphous chalcogenide compound, comprising the following steps: (1) Synthesizing Au nanorods by seed growth method; (2) Silver is coated on the surface of Au nanorods, and silver shell nanocrystals are epitaxially grown to obtain Au@Ag nanorods; (3) Au@Ag nanorods are dispersed in water, and an aqueous sulfur precursor is added for sulfidation to obtain Au@Ag2S nanorods, wherein the volume ratio of Au@Ag nanorods to the aqueous sulfur precursor is 1:(0.0007~0.003); wherein the aqueous sulfur precursor is prepared by sulfur powder and sodium sulfide aqueous solution under hydrothermal conditions; (4) Au@Ag2S nanorods were dispersed in a hexadecyltrimethylammonium bromide solution, and Zn(NO3)2 aqueous solution and triphenylphosphine toluene solution were added sequentially. The hydrothermal reaction was carried out at 60-80℃. After cooling, the mixture was allowed to stand for 10-36 hours to obtain Au@ZnS core-shell nanocrystals with a partially hollow surface structure. The proportion of the amorphous surface was 10-50%, and the proportion of the cavity volume was 5-40%.

2. The production method according to claim 1, characterized by, Step (1) includes: Step (1-1): Disperse HAuCl4 in an aqueous solution of hexadecyltrimethylammonium bromide, add an aqueous solution of NaBH4, and prepare a seed solution; Steps (1-2): Disperse HAuCl4 in a mixed aqueous solution of hexadecyltrimethylammonium bromide and dodecyldimethylbenzylammonium chloride, and add AgNO3 and ascorbic acid aqueous solution in sequence to prepare the growth solution; Steps (1-3): Add the seed solution to the growth solution for aging, and centrifuge to obtain Au nanorods.

3. The production method according to claim 2, characterized by, In step (1-1), the molar ratio of HAuCl4, hexadecyltrimethylammonium bromide, and NaBH4 is 1: (380~420):(2.3~2.5); In steps (1-2), the molar ratio of HAuCl4, hexadecyltrimethylammonium bromide, dodecyldimethylbenzylammonium chloride, AgNO3, and ascorbic acid is 1: (190~250): (190~290): (0.1~0.3): (1~1.5).

4. The preparation method according to claim 2, characterized in that, In steps (1-3), the volume ratio of seed solution to growth solution is 1:(850~1300), and the aging time is 8~16h.

5. The preparation method according to claim 1, characterized in that, Step (2) includes: Au nanorods were dispersed in a hexadecyltrimethylammonium bromide solution, and AgNO3, ascorbic acid, and NaOH were added sequentially under heating conditions to obtain Au@Ag nanorods. The heating temperature was 30~40℃, and the molar ratio of Au nanorods, hexadecyltrimethylammonium bromide, AgNO3, ascorbic acid, and NaOH was 1: (1~1.5): (0.001~0.003): (0.4~0.6): (0.4~0.6).

6. The method of claim 1, wherein, In step (4), The molar ratio of Au@Ag2S nanorods, hexadecyltrimethylammonium bromide, Zn(NO3)2, and triphenylphosphine is 1:(0.5~1.5):(0.1~0.5):(0.2~0.6).

7. A core-shell nanocrystal of metal- amorphous chalcogenide compound, characterized in that, The core-shell nanocrystal of metal-amorphous structure chalcogenide is prepared by the preparation method of any one of claims 1-6.

8. Use of the core-shell nanocrystal of metal-amorphous structure chalcogenide of claim 7 in photocatalytic reduction of carbon dioxide.

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