Nanotwinned gold particles, method for preparing the same and use thereof

Abstract

The application discloses a kind of nano twin crystal gold particles and its preparation method and application, the application utilizes pulse infrared laser, through the mixture of covalent organic framework material and chloroauric acid as precursor is carried out laser direct writing, so that chloroauric acid is loaded to the carbon material of covalent organic framework under laser high temperature under laser reduction, to obtain nano twin crystal gold particle load on the composite material of carbon nanosheet.The material can be used as photocatalyst simultaneously, in the photocatalytic reduction reaction of carbon dioxide, obtain carbon monoxide and methane and other fuel products, show good photocatalytic performance.The laser direct writing preparation method involved in the application only uses covalent organic framework material and chloroauric acid as reactant, ethanol is used as only solvent, so that the whole synthesis process is green and fast, can be prepared in large quantities.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, and in particular to a nanotwinned gold particle, its preparation method, and its application. Background Technology

[0002] Lasers, as a powerful tool, hold immense potential for synthesizing metal nanoparticles, graphene, and various nanocomposites (see Hu, H. et al. Matter, 2020, 3, 95-126). Loading highly dispersed metal nanoparticles onto carbon materials is a highly effective method for obtaining such nanoparticles. However, direct laser writing of metal-organic frameworks (MOFs) typically only allows loading metal nanoparticles with low coordination numbers onto carbon materials (see Jiang, H. et al. Matter, 2020, 2, 1535-1549). For photocatalysis, due to the high coordination number of gold, gold-based MOFs are rare, making it impossible to directly obtain carbon-loaded gold nanoparticles by writing gold MOFs. Furthermore, metal nanoparticles obtained using direct MOF writing exhibit limited catalytic performance due to the lack of abundant internal crystal defects and insufficient bonding between the nanoparticles and the support, hindering efficient electron and hole transport. Considering that nanotwinned metal particles have significant catalytic performance for photocatalysis, current methods for preparing nanotwinned particles are all concentrated on traditional wet chemical methods (see Liu, M. et al. Nature Energy, 2016, 1, 16151).

[0003] Current synthesis methods have not yet been able to directly load nanotwinned particles onto carbon nanosheets using laser energy, and traditional methods also face challenges in achieving green, large-scale preparation. Therefore, it is necessary to develop a nanotwinned gold particle with excellent photocatalytic performance and a simple preparation method, along with its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a nanotwinned gold particle, its preparation method and application. The prepared nanotwinned gold particle is uniformly loaded onto carbon nanosheets, which is a structure that is difficult to obtain by traditional chemical methods. In the photocatalytic reduction of carbon dioxide, it can reduce carbon dioxide to carbon monoxide and methane, showing good photocatalytic effect.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect of the present invention, a method for preparing nanotwinned gold particles is provided, the method comprising:

[0007] After dispersing the covalent organic framework in a chloroauric acid solution, a mixture solution was obtained, which was then dried and ground to obtain a mixture precursor powder.

[0008] The precursor powder of the mixture was laser-written using a single-pulse nanosecond infrared laser to obtain nanotwinned gold particles.

[0009] Furthermore, the covalent organic framework material is TPB-BMTP-COF.

[0010] Furthermore, the concentration of the covalent organic framework added to the chloroauric acid solution ranges from 10 to 100 mmol / L.

[0011] Furthermore, the conditions for laser direct writing are as follows: the laser direct writing path interval is 0.1-1 mm, the direct writing speed is 10-100 mm / s, the laser power is 5-30 W, the repetition frequency is 2-20 kHz, the laser spot size is 100-1000 μm, and the wavelength is 1064 nm-10.6 μm.

[0012] Furthermore, the laser direct writing of the mixture precursor powder using a single-pulse nanosecond infrared laser specifically includes:

[0013] A copper foil with a central hole is placed on a glass slide. The precursor powder of the mixture is spread in the central hole of the copper foil. Then, another glass slide is placed on the copper foil, and the two glass slides are glued and fixed together with tape to obtain a sample for laser direct writing.

[0014] A pulsed laser is used to scan the mixture precursor powder located in the central hole of the copper foil.

[0015] In a second aspect of the invention, nanotwinned gold particles obtained by the method are provided.

[0016] Furthermore, the size of the nanotwinned gold particles is 2nm to 100nm.

[0017] In a third aspect of the invention, the application of the aforementioned nanotwinned gold particles in the preparation of photocatalytic materials is provided.

[0018] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0019] 1. The nanotwinned gold particles prepared by this invention are uniformly loaded onto carbon nanosheets, which is a structure that is difficult to obtain by traditional chemical methods, and the size and loading of the nanotwinned gold particles are easy to control.

[0020] 2. The laser manufacturing method provided by this invention only requires a single laser reaction to obtain the product, which greatly shortens the synthesis steps. No active agents or other organic reagents other than the reactants are used in the synthesis process, resulting in a product with high purity. It is a typical green and environmentally friendly preparation process that can be mass-produced.

[0021] 3. The material prepared by this invention can be used as a photocatalyst material. In the photocatalytic reduction of carbon dioxide, it can reduce carbon dioxide to carbon monoxide and methane, showing good photocatalytic effect. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a transmission electron microscope image of the morphology of the nanotwinned gold particles prepared in this invention.

[0024] Figure 2 This is the XRD pattern of the nanotwinned gold particles prepared by this invention.

[0025] Figure 3 This is a graph showing the performance of photocatalytic carbon dioxide reduction by nanotwinned gold particles prepared in this invention. Detailed Implementation

[0026] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0027] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0028] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be obtained by purchasing them from the market or by existing methods.

[0029] The technical solution of this application embodiment is to solve the above-mentioned technical problems, and the general idea is as follows:

[0030] According to a typical embodiment of the present invention, a method for preparing nanotwinned gold particles is provided, the method comprising:

[0031] S1. After dispersing the covalent organic framework in chloroauric acid solution, a mixture solution is obtained, which is then dried and ground to obtain a mixture precursor powder.

[0032] In step S1

[0033] The covalent organic framework material is TPB-BMTP-COF.

[0034] The concentration of the chloroauric acid solution is 10–100 mmol / L. The mass ratio of the covalent organic framework to the gold element in the chloroauric acid solution is 6:1 to 1:1. This range aims to control the loading of gold nanoparticles to account for 10%–60% of the total material.

[0035] S2. The mixture precursor powder is laser-written using a single-pulse nanosecond infrared laser to obtain nanotwinned gold particles.

[0036] In step S2

[0037] The conditions for laser direct writing are as follows: the laser direct writing path interval is 0.1-1 mm, the direct writing speed is 10-100 mm / s, the laser power is 5-30 W, the repetition frequency is 2-20 kHz, the laser spot size is 100-1000 μm, and the wavelength is 1064 nm-10.6 μm.

[0038] Preferably, the conditions for laser direct writing are: laser direct writing path interval of 0.5 mm, direct writing speed of 65 mm / s, laser power of 12 W, repetition frequency of 20 kHz, and laser spot size of 500 μm.

[0039] The laser direct writing time is 1 to 3 hours.

[0040] As an optional implementation, the mixture precursor powder is laser-written using a single-pulse nanosecond infrared laser, specifically including:

[0041] A copper foil with a central hole is placed on a glass slide. The precursor powder of the mixture is spread in the central hole of the copper foil. Then, another glass slide is placed on the copper foil, and the two glass slides are glued and fixed together with tape to obtain a sample for laser direct writing.

[0042] A pulsed laser is used to scan the mixture precursor powder located in the central hole of the copper foil.

[0043] In one specific embodiment, the copper foil with a central hole has a thickness of 10 μm, a length and width of 25 mm, and a diameter of 12 mm. This dimensional design facilitates laser penetration of the precursor powder during laser-written samples, ensuring a complete reaction.

[0044] According to another typical embodiment of the present invention, nanotwinned gold particles obtained by the method are provided.

[0045] The size of the nanotwinned gold particles is 2nm-100nm.

[0046] The loading of gold nanoparticles in the composite material can be adjusted by controlling the content and ratio of the mixed chloroauric acid and covalent organic framework. Increasing the mixing ratio of chloroauric acid and covalent organic framework will effectively increase the loading of gold nanoparticles in the final product. The size of the nanotwinned gold particles can also be adjusted by controlling the laser parameters. Increasing the laser power and decreasing the scanning speed can effectively increase the size of the nanotwinned particles.

[0047] This material consists of nanotwinned gold particles loaded onto carbon nanosheets. The size of the nanotwinned gold particles is controlled between 2 nm and 100 nm, and the loading of gold nanoparticles accounts for 10% to 60% of the total material. Specifically, the loading of 10% to 60% of the total material can be controlled by adjusting the mass ratio of the covalent organic framework to the gold element in the chloroauric acid solution to a range of 6:1 to 1:1.

[0048] According to another typical embodiment of the present invention, the application of the aforementioned nanotwinned gold particles in the preparation of photocatalytic materials is provided.

[0049] In summary, this invention aims to prepare uniformly dispersed nanotwinned gold particles loaded onto carbon nanosheets in a more environmentally friendly and large-scale manner. Utilizing the instantaneous high temperature generated by laser direct writing, a mixture of covalent organic frameworks (COFs) and metal salts is rapidly pyrolyzed. This allows for the simultaneous pyrolysis of the COFs into carbon nanosheets and the reduction of the metal into nanotwinned particles, which are then uniformly loaded onto the carbon nanosheets. When used as a photocatalyst, the resulting nanotwinned gold particle material on carbon nanosheets exhibits highly efficient catalytic performance and high selectivity for the products during the reduction of carbon dioxide.

[0050] The following will provide a detailed description of a nanotwinned gold particle, its preparation method, and its application, in conjunction with embodiments, comparative examples, and experimental data.

[0051] Example 1

[0052] (1) 60 mg of covalent organic framework TPB-BMTP-COF was added to 3 ml of a pre-prepared chloroauric acid solution with a concentration of 20 mmol / L, and then ultrasonically dispersed for 30 minutes. After that, the dispersed mixture was transferred to an oven and dried at 60°C for 12 hours. The resulting solid mixture after removing ethanol was ground into powder using a mortar and pestle. To prevent moisture absorption, the mixture precursor powder was sealed for later use.

[0053] (2) Place a copper foil with a central punch (hole diameter of 12mm) of 25mm in length and width and 10μm in thickness on a glass slide. Then take 3mg of the mixture powder and spread it evenly in the hole of the copper foil. Then cover the copper foil with another glass slide and use tape to stick the two glass slides together to fix them as a laser-written sample.

[0054] (3) Turn on the pulsed laser with a wavelength of 1064nm, set the laser parameters, the direct writing path interval is 0.5mm, the direct writing speed is 65mm / s, the laser power is 12W, the repetition frequency is 20KHz, the laser spot is 500μm, and the laser spot is uniformly swept across the precursor powder located in the middle of the copper foil. Then, the other side of the powder is also laser-written. After the direct writing on both sides is completed, disassemble the sample device for laser direct writing. The sample that was swept by the laser in the middle is the nanotwinned gold particle sample loaded on the carbon nanosheet.

[0055] Example 2

[0056] (1) 60 mg of covalent organic framework TPB-BMTP-COF was added to 2 ml of a chloroauric acid solution with a concentration of 20 mmol / L, and then ultrasonically dispersed for 30 minutes. After that, the dispersed mixture was transferred to an oven and dried at 60°C for 12 hours. The resulting solid mixture after removing ethanol was ground into powder using a mortar and pestle. To prevent moisture absorption, the precursor powder of the mixture was sealed for later use.

[0057] (2) Place a copper foil with a central punch (hole diameter of 12mm) of 25mm in length and width and 10μm in thickness on a glass slide. Then take 3mg of the mixture powder and spread it evenly in the hole of the copper foil. Then cover the copper foil with another glass slide and use tape to stick the two glass slides together to fix them as a laser-written sample.

[0058] (3) Turn on the pulsed laser with a wavelength of 1064nm, set the laser parameters, the direct writing path interval is 0.5mm, the direct writing speed is 65mm / s, the laser power is 12W, the repetition frequency is 20KHz, the laser spot is 500μm, and the laser spot is uniformly swept across the precursor powder located in the middle of the copper foil. Then, the other side of the powder is also laser-written. After the direct writing on both sides is completed, disassemble the sample device for laser direct writing. The sample that was swept by the laser in the middle is the nanotwinned gold particle sample loaded on the carbon nanosheet.

[0059] Example 3

[0060] (1) 60 mg of covalent organic framework TPB-BMTP-COF was added to 4 ml of a pre-prepared chloroauric acid solution with a concentration of 20 mmol / L. The mixture was then ultrasonically dispersed for 30 minutes. After that, the dispersed mixture was transferred to an oven and dried at 60°C for 12 hours. The resulting solid mixture after removing ethanol was ground into powder using a mortar and pestle. To prevent moisture absorption, the precursor powder of the mixture was sealed for later use.

[0061] (2) Place a copper foil with a central punch (hole diameter of 12mm) of 25mm in length and width and 10μm in thickness on a glass slide. Then take 3mg of the mixture powder and spread it evenly in the hole of the copper foil. Then cover the copper foil with another glass slide and use tape to stick the two glass slides together to fix them as a laser-written sample.

[0062] (3) Turn on the pulsed laser with a wavelength of 1064nm, set the laser parameters, the direct writing path interval is 0.5mm, the direct writing speed is 65mm / s, the laser power is 12W, the repetition frequency is 20KHz, the laser spot is 500μm, and the laser spot is uniformly swept across the precursor powder located in the middle of the copper foil. Then, the other side of the powder is also laser-written. After the direct writing on both sides is completed, disassemble the sample device for laser direct writing. The sample that was swept by the laser in the middle is the nanotwinned gold particle sample loaded on the carbon nanosheet.

[0063] Comparative Example 1

[0064] The comparative example is TPB-DMTP-COF. The specific preparation method of this material includes: 1,3,5-tris-(4-aminophenyl)benzene (TAPB) (0.080 mmol, 28.1 mg) and 2,5-o-dimethylterephthalaldehyde (DMTA) (0.120 mmol, 23.3 mg) in a mixture of o-dichlorobenzene (o-DCB) / n-butane (n-BuOH) (0.5 / 0.5 ml) in a Pyrex tube (10 ml) in the presence of an acetic acid catalyst (6 M, 0.1 ml) through three cycles of refrigeration pump-thawing. The mixture was flame-sealed and heated at 120 °C for 3 days. The precipitate was collected by centrifugation, washed six times with tetrahydrofuran, and then subjected to Soxhlet extraction with tetrahydrofuran as solvent for 1 day to remove trapped guest molecules. The collected powder was vacuum-dried overnight at 120 °C, yielding TPB-DMTP-COF in 81% yield.

[0065] Experimental Example 1: Material Characterization

[0066] The XRD pattern of the nanotwinned gold particle sample loaded onto carbon nanosheets prepared in Example 1 is shown below. Figure 2 As shown, the typical XRD characteristic spectrum of gold nanoparticles can be seen, indicating that the gold element in the sample exists entirely in the form of elemental form.

[0067] Experimental Example 2: Photocatalytic Applications

[0068] The nanotwinned gold particles prepared in Example 1 and the TPB-BMTP-COF of Comparative Example 1 were subjected to photocatalytic carbon dioxide reduction experiments. The specific experimental steps are as follows:

[0069] The photocatalytic CO2 reduction experiment was conducted in a 200 mL reactor under a light-irradiated simulator. First, 5 mL of deionized water was added to the reactor, followed by ultrasonic mixing and dispersion of 15 mg of sample. The suspension was evaporated at 60 °C to form a thin film. After drying, 2 mL of deionized water was added to the quartz reactor containing the film material. The reactor was connected to the light-irradiated simulator, and after evacuation, high-purity CO2 gas was introduced. This process was repeated three times to ensure thorough exchange of the internal atmosphere of the reactor, ultimately maintaining the pressure inside the reactor at 80 kPa. Gas chromatography was used to analyze the gas composition inside the reactor every 25 minutes to obtain the types and yields of photocatalyzed products.

[0070] The performance of photocatalytic carbon dioxide reduction by nanotwinned gold particles in Example 1 is shown in the figure below. Figure 3 As shown, the comparison sample did not exhibit significant photocatalytic performance; however, the laser-prepared nanotwinned gold particles of this invention showed a significant catalytic reduction ability for carbon dioxide, with photocatalytic products including carbon monoxide and methane, wherein the carbon monoxide yield was 950 μmol g. -1 h -1The yield of methane was 385 μmol g. -1 h -1 .

[0071] Finally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0072] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0073] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing nanotwinned gold particles, characterized in that, The method includes: The covalent organic framework material TPB-BMTP-COF was dispersed in a chloroauric acid solution to obtain a mixed solution, which was then dried and ground to obtain a mixed precursor powder; the concentration of the chloroauric acid solution was 15-25 mmol / L; the concentration of the covalent organic framework added to the chloroauric acid solution was in the range of 10-100 mmol / L. The mixture precursor powder was laser-written using a single-pulse nanosecond infrared laser to obtain nanotwinned gold particles. The conditions for laser direct writing are as follows: the laser direct writing path interval is 0.1-1 mm, the direct writing speed is 10-100 mm / s, the laser power is 5-30 W, the repetition frequency is 2-20 KHz, the laser spot size is 100-1000 μm, and the wavelength is 1064 nm-10.6 μm. The mixture precursor powder is laser-written using a single-pulse nanosecond infrared laser, specifically including: A copper foil with a central hole is placed on a glass slide. The precursor powder of the mixture is spread in the central hole of the copper foil. Then, another glass slide is placed on the copper foil, and the two glass slides are glued and fixed together with tape to obtain a sample for laser direct writing. A pulsed laser is used to scan the mixture precursor powder located in the central hole of the copper foil; the copper foil with the central hole has a thickness of 10 μm, a length and width of 25 mm, and a diameter of 12 mm.

2. The method for preparing nanotwinned gold particles according to claim 1, characterized in that, The nanotwinned gold particles prepared by the method have a size of 2 nm to 100 nm.

3. The application of the nanotwinned gold particles prepared by the method of claim 1 in the preparation of photocatalytic materials.

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