Preparation method of Au nano material with layered hybrid superlattice structure

Abstract

The invention belongs to the technical field of nano materials, and discloses a preparation method of an Au nano material with a layered hybrid superlattice structure. According to the method, a coordination confinement synthesis strategy is adopted, 4-mercaptobenzoic acid is taken as a structure-directing agent, and the organic-inorganic alternating layered superlattice structure is successfully prepared under the condition of CO weak reduction by utilizing a strong coordination bond formed by sulfydryl of 4-mercaptobenzoic acid and gold and a pi-pi conjugate synergistic effect of a benzene ring and combining a soft template confinement effect of octadecylamine. The superlattice material has a long-range disordered amorphous structure and an adjustable interlayer spacing (2.9 to 4.7 nm), and shows the white light emission characteristics of wide-spectrum ultraviolet-visible absorption (250 to 600 nm) and adjustable color temperature (3200 to 6500 K). According to the invention, a quantitative structure-function relationship of interlayer spacing-ligand metal interaction-optical performance is established, effective regulation and control of intersystem crossing process and phosphorescence lifetime from microsecond to millisecond magnitude are realized, and an innovative solution is provided for solving the problem of metal-organic layer interface compatibility; and an important material platform and theoretical support are provided for developing a novel flexible photoelectric device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of new material preparation of inorganic compounds, and particularly relates to a preparation method of a layered hybrid superlattice material. BACKGROUND

[0002] Superlattice structure materials have long been considered as a core material system of high-performance optoelectronic and photonic devices, and are widely used in traditional optoelectronic components such as optical modulators, lasers, photodetectors, and the like, and show important potential in emerging fields such as communication, biomedicine and sensing. However, most of the widely used multiple quantum wells and superlattice materials are prepared by epitaxial growth technology. Although such materials have made some progress in commercialization, the preparation process is complex, the cost is high, and it is difficult to realize integration with any substrate, which greatly limits the further expansion of its application range.

[0003] In recent years, two-dimensional semiconductor materials based on intermolecular forces self-assembly have attracted widespread attention due to their ability to achieve large-area uniform growth and easy transfer to a variety of substrates. Such materials are usually composed of atomic-thick metal layers stacked by weak interactions, and have tunable electronic band, optical and mechanical properties, providing a new platform for precise design of electronic and photonic behavior in artificial superlattice structures, and laying a material foundation for the development of a new generation of high-efficiency energy conversion devices and micro-nano functional elements. Therefore, it is urgent to construct superlattice materials with periodic stacking structure, which not only can enhance the coupling efficiency between light and matter, but also can introduce more abundant optical properties through band engineering, thereby expanding the application prospects of two-dimensional materials in the field of optoelectronics. SUMMARY

[0004] The present application aims to solve the technical problem in the prior art that it is difficult to accurately control the interlayer interaction of Au nanomaterials in superlattice structures to customize their optical properties. Specifically, the purposes of the present application include: 1. To provide an innovative synthesis strategy to overcome the tendency of gold and long-chain alkyl ligands to form three-dimensional clusters or nanoparticles by direct coordination, and to achieve controllable synthesis of superlattice materials.

[0005] 2. By precisely designing the ligand chemistry, an organic-inorganic alternating superlattice structure material with adjustable interlayer spacing is constructed, thereby effectively suppressing interlayer molecular vibration and achieving precise control of the photoelectric properties (especially the luminescence behavior) of the material.

[0006] In order to achieve the above purposes of the present application, the following technical solution is adopted: A coordination limited synthesis method of superlattice material, the core of which is to use ligand-induced amorphization strategy, synergistically use Au-S strong coordination bond and π-π conjugation effect, and combine the space limited function of long-chain amine ligand. The specific steps are as follows: (1) Gold acetate (Au(CH3COO)3), chromium hexacarbonyl (Cr(CO)6), 4-mercaptobenzoic acid (C7H6O2S) and octadecylamine (C 18 H 39 N) Mixed at a specific molar ratio.

[0007] (2) The mixture was heated in an oil bath at 90°C until partially melted. It was first slowly stirred at 1500 rpm until completely melted, and then the speed was increased to 3000 rpm and stirred continuously for 3 hours. During this process, CO produced by the decomposition of Cr(CO)6 acts as a mild reducing agent to reduce Au(III) to Au(0), and the color of the mixture changes from grayish-white to yellow transparent solution.

[0008] (3) Add ethanol and n-hexane to the solution after the reaction and continue stirring to induce the precipitation of the product. Then centrifuge (8000 rpm, 3 min) and wash the white precipitate twice with ethanol.

[0009] (4) The suspension obtained in step (3) is separated by a centrifuge and dried in an oven at 30-50°C to obtain a solid powder, which is the layered hybrid superlattice material prepared in this invention.

[0010] In this invention, unless otherwise specified, the solutions used are prepared under conventional conditions, such as by dissolving the substance in an aqueous solution at room temperature.

[0011] In this invention, unless otherwise specified, the apparatus, instruments, equipment, materials, processes, methods, steps, preparation conditions, etc. used are all conventionally used in the art or can be easily obtained by those skilled in the art using conventional techniques.

[0012] This invention relates to a method for synthesizing Au nanomaterials with a superlattice structure. The room temperature refers to a temperature range of 20℃-35℃.

[0013] Furthermore, the gold source can be an organogold compound such as gold triacetate, and its preferred dosage is 0.05–0.06 mmol.

[0014] Furthermore, the chromium carbonyl compound may be selected from chromium hexacarbonyl, etc., and the amount used is preferably 0.04–0.05 mmol.

[0015] Furthermore, sulfur sources can be selected from sulfur-containing organic compounds such as benzothiophene and mercaptobenzimidazole, but are not limited to these, and their amount is preferably 1.2–1.4 mmol.

[0016] Furthermore, the surfactant can be a long-chain alkylamine compound such as trioctylamine, oleylamine, or hexadecyltrimethylammonium bromide, and the preferred amount is 7.0–7.5 mmol.

[0017] Furthermore, the heating temperature in the step is preferably 80–100°C.

[0018] Furthermore, the stirring speed can be controlled within the range of 1000–3000 rpm.

[0019] Furthermore, the reaction can be carried out under an inert atmosphere, such as nitrogen or argon.

[0020] Furthermore, organic solvents such as ethanol, n-hexane, and acetone can be used for washing and centrifugation during the purification process.

[0021] Furthermore, the centrifugation speed can be controlled at 5000–10000 rpm, and the centrifugation time can be 2–5 min.

[0022] Furthermore, the prepared superlattice materials have a size in the range of 50–400 nm and a thickness in the range of 5–50 nm.

[0023] Furthermore, the superlattice material prepared by this method has a regular layered structure and tunable surface activity, which can be applied to fields such as photoelectric conversion, and exhibits good stability.

[0024] The key innovation of this invention lies in the ligand design: Innovatively, 4-mercaptobenzoic acid is introduced as a key ligand. Its thiol group (-SH) forms a strong coordination bond with gold atoms (bond energy >200 kJ / mol), while its benzene ring structure constructs a rigid framework through π-π conjugated stacking. The synergistic effect of these two ligands effectively inhibits the three-dimensional anisotropic growth and crystallization of gold atoms.

[0025] Octadecylamine is used simultaneously as a solvent, surfactant, and soft template. The strong intermolecular forces between its long-chain alkylamines form an atomically confined reactor in the reaction system, forcing gold atoms to undergo two-dimensional growth and self-assembly.

[0026] The above process successfully prepared organic-inorganic alternating layered superlattice Au nanomaterials, whose gold atom layers exhibit a long-range disordered amorphous structure, and the interlayer spacing can be precisely controlled within the range of 2.9 nm to 4.7 nm.

[0027] This invention is the first to synthesize a material with a layered superlattice, and the synthesis method has the following advantages: 1. The reaction conditions of this invention are mild, and the prepared layered superlattice materials have uniform morphology and size; 2. The layered superlattice material prepared in this invention has excellent and tunable optical properties; 3. The interlayer spacing and other properties of the layered superlattice material prepared by this invention can be adjusted by selecting different solvents. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope image of the Au nanomaterial with a superlattice structure obtained in Example 1 of the present invention; Figure 2 This is a transmission electron micrograph of the Au nanomaterial with a superlattice structure obtained in Example 1 of the present invention; Figure 3 This is a transmission electron micrograph of the Au nanomaterial with a superlattice structure obtained in Example 2 of the present invention; Figure 4 This is a transmission electron micrograph of the Au nanomaterial with a superlattice structure obtained in Example 3 of the present invention; Figure 5 The phosphorescence spectrum of the Au nanomaterial with a superlattice structure obtained in Example 1 of this invention is shown. Figure 6 The phosphorescence spectra of Au nanomaterials with superlattice structures obtained in Examples 1, 2 and 3 of this invention are shown. Figure 7 This is a color temperature coordinate graph showing the change of excitation wavelength in Embodiment 1 of the present invention. Detailed Implementation

[0029] The embodiments of the present invention will be described in detail below with reference to the examples. These examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified, specific conditions in the examples are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0030] The present invention will be further described below with reference to specific embodiments and accompanying drawings. Example

[0031] 0.05346 mmol gold triacetate, 0.04544 mmol chromium hexacarbonyl, 1.297 mmol 4-mercaptobenzoic acid (C7H6O2S) and 7.421 mmol oleylamine (C 18 H 39The mixture (N) was heated in a 90°C oil bath until partially melted, and stirred at 1500 rpm until completely liquefied. The stirring speed was then increased to 3000 rpm for 3 hours, during which the solution gradually changed from grayish-white to a yellow transparent liquid. 10 mL of ethanol and 10 mL of n-hexane were added, and stirring continued for 3 minutes to obtain a golden-yellow solution. After standing at room temperature for 1 minute, the solution was centrifuged at 8000 rpm for 3 minutes. The white precipitate was collected and washed twice with ethanol to finally obtain a white layered hybrid superlattice material. Example

[0032] 0.05346 mmol gold triacetate, 0.03635 mmol chromium hexacarbonyl, 0.1621 mmol 4-mercaptobenzoic acid, and 15.48 mmol dodecylamine (C 12 H 27 The mixture (N) was stirred at 78°C and 3000 rpm for 3 hours, and the mixture gradually changed from white to light gray. The reaction solution was allowed to stand at room temperature for 2 minutes, then centrifuged at 8000 rpm for 1 minute. The precipitate was washed twice with ethanol to obtain a light gray layered hybrid superlattice material. Example

[0033] 0.05346 mmol gold triacetate, 0.01818 mmol chromium hexacarbonyl, 0.1038 mmol 4-mercaptobenzoic acid, and 10.79 mmol trioctylamine (C8H) were added. 19 The mixture (N) was heated in an oil bath at 78°C until partially melted. It was first stirred at 1500 rpm until fully liquid, then the stirring speed was increased to 3000 rpm for 3 hours, during which the mixture changed from white to purplish-red. After the reaction was complete, the mixture was allowed to stand at room temperature for 2 minutes, then centrifuged at 8000 rpm for 1 minute. The precipitate was washed with ethanol to obtain a purplish-red layered hybrid superlattice material. Example

[0034] Using the same material ratio and heating and stirring process as in Example 1, a yellow transparent solution was obtained. Then, 10 mL of n-hexane was added first, followed by 10 mL of ethanol, and stirring was continued for 3 minutes to obtain a golden yellow solution. The solution was allowed to stand at room temperature for 1 minute, centrifuged at 8000 rpm for 3 minutes, and the purplish-red precipitate was collected and washed twice with ethanol to obtain a purplish-red layered hybrid superlattice material. Example

[0035] 0.06 mmol gold triacetate, 0.05 mmol chromium hexacarbonyl, 1.3 mmol 4-mercaptobenzoic acid, and 7.5 mmol oleylamine were mixed and stirred at 2000 rpm at 85 °C until melted. The mixture was then reacted at 3000 rpm for 3.5 hours, during which time the solution gradually turned orange-yellow. 12 mL ethanol and 8 mL n-hexane were added, and the mixture was stirred for 3 minutes. After standing at room temperature for 1 minute, the mixture was centrifuged at 10000 rpm for 2 minutes. The precipitate was washed with ethanol to obtain a yellow layered hybrid superlattice material. Example

[0036] 0.05 mmol gold triacetate, 0.04 mmol chromium hexacarbonyl, 1.4 mmol 4-mercaptobenzoic acid, and 8.0 mmol hexadecylamine were mixed and melted at 95 °C with stirring at 1000 rpm, followed by reaction at 2500 rpm for 4 hours. The system changed from milky white to reddish-brown. 15 mL acetone was added, and stirring was continued for 5 minutes. After standing, the mixture was centrifuged at 9000 rpm for 4 minutes. The precipitate was washed three times with ethanol to obtain a reddish-brown layered hybrid superlattice material. Example

[0037] 0.055 mmol gold triacetate, 0.048 mmol chromium hexacarbonyl, 1.0 mmol 2-mercaptobenzothiazole, and 7.0 mmol oleylamine were mixed and reacted at 80 °C with stirring at 3000 rpm for 2 hours. The solution changed from light yellow to dark green. 10 mL of n-hexane and 10 mL of isopropanol were added, and the mixture was stirred for 5 minutes. After standing at room temperature for 2 minutes, the mixture was centrifuged at 8000 rpm for 3 minutes. After washing the precipitate, a dark green layered hybrid superlattice material was obtained. Example

[0038] 0.052 mmol gold triacetate, 0.042 mmol chromium hexacarbonyl, 1.5 mmol 2-mercaptoethanol, and 8.5 mmol tributylamine were mixed and stirred at 1800 rpm at 88 °C until liquid, then reacted at 3200 rpm for 3 hours. The mixture gradually turned bright yellow. After adding 10 mL of ethanol, the mixture was centrifuged at 7000 rpm for 5 minutes. The precipitate was washed twice with ethanol to obtain a bright yellow layered hybrid superlattice material. Example

[0039] 0.057 mmol gold triacetate, 0.046 mmol chromium hexacarbonyl, 0.2 mmol dodecyl mercaptan, and 9.0 mmol dioctylamine were mixed and reacted at 82 °C and stirred at 2800 rpm for 3.5 hours. The solution changed from colorless to blue-violet. 12 mL of n-hexane was added, and the mixture was stirred for 3 minutes. After standing at room temperature, the mixture was centrifuged at 10000 rpm for 2 minutes. The precipitate was washed with ethanol to obtain a blue-violet layered hybrid superlattice material. Example

[0040] 0.05 mmol gold triacetate, 0.045 mmol chromium hexacarbonyl, 1.2 mmol thiosalicylic acid, and 7.2 mmol oleylamine were mixed and melted at 92 °C with stirring at 1500 rpm. The reaction was then increased to 3500 rpm and carried out for 2.5 hours, during which the solution gradually turned brownish-red. 10 mL methanol and 10 mL chloroform were added, and the mixture was stirred for 4 minutes. After standing, the mixture was centrifuged at 8500 rpm for 3 minutes, and the precipitate was washed to obtain a brownish-red layered hybrid superlattice material.

Claims

1. A method for preparing Au nanomaterials of layered hybrid superlattice structures, characterized in that, The method comprises the following steps: (a) mixing reaction step: mixing a gold source compound, a chromium source compound, a sulfur source compound and a long-chain amine solvent, heating at 90-100°C, and stirring at a first rotating speed until the mixture is completely liquefied, then increasing the rotating speed to a second rotating speed and continuously stirring for 1-4 hours to carry out the reaction, and obtaining a golden yellow transparent reaction solution; (b) precipitation step: adding an alcohol solvent and an alkane solvent to the reaction solution obtained in step (a) and continuously stirring to induce the product to precipitate; (c) separation and purification step: centrifuging the solution obtained in step (b), collecting the precipitate and washing with an alcohol solvent, and obtaining the Au nanomaterial with superlattice structure.

2. The method of synthesis of claim 1, wherein, In step (a), the gold source compound is gold acetate (Au(CH3COO)3), the chromium source compound is chromium hexacarbonyl (Cr(CO)6), the sulfur source compound is mercaptobenzyl alcohol (C7H6O2S), and the long-chain amine solvent is oleylamine (C 18 H 39 N), dodecylamine (C 12 H 27 N), and octylamine (C8H 19 N).

3. The method of synthesis according to claim 1 or 2, wherein, In step (a), the molar ratio of the reactants is: the gold source compound: the chromium source compound: the sulfur source compound: the long-chain amine solvent = 1: (0.8-1.2): (20-30): (130-150).

4. The method of synthesis of claim 3, wherein, The molar ratio of the reactants is: gold acetate: chromium hexacarbonyl: mercaptobenzyl alcohol: oleylamine = 1: 0.85: 24.26: 138.

80.

5. The method of synthesis of claim 1, wherein, In step (a), the first rotating speed is 1000-2000 rpm, and the second rotating speed is 2500-3500 rpm; the reaction time is 2-4 hours.

6. The method of synthesis of claim 5, wherein, In step (a), the first rotating speed is 1500 rpm, and the second rotating speed is 3000 rpm; the reaction time is 3 hours.

7. The method of synthesis of claim 1, wherein, In step (b), the alcohol solvent is ethanol or methanol, and the alkane solvent is n-hexane, n-heptane or n-pentane.

8. The method of synthesis of claim 7, wherein, In step (b), the volume of the alcohol solvent and the alkane solvent added is 8-12 mL respectively, and the stirring is continued for 2-5 minutes after the addition.

9. The method of synthesis of claim 1, wherein, In step (c), the rotating speed of centrifugation is 7000-9000 rpm, and the time is 2-4 minutes; the washing times is 1-3 times.

10. The Au nanomaterial with superlattice structure prepared by the method of any one of claims 1-9.

11. The Au nanomaterial with superlattice structure of claim 10 for use in catalysis, sensing or optoelectronic devices.

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