CN111636057A - A silver triangular nanoparticle array/monolayer graphene film composite - Google Patents

Abstract

The invention discloses a silver triangular nanoparticle array/single-layer graphene film composite material, which comprises the following steps: growing a single-layer graphene film on a copper foil; secondly, assembling a single-layer PS sphere template and transferring the single-layer PS sphere template to a copper foil attached with single-layer graphene; then, depositing silver by thermal evaporation, wherein a sample is kept still in the deposition process; and finally, removing the PS spheres to obtain the silver triangular nanoparticle array on the single-layer graphene film. According to the invention, the silver triangular nanoparticle array is controllably grown on the single-layer graphene, the respective advantages of the silver triangular nanoparticle array and the single-layer graphene and the synergistic effect of the silver triangular nanoparticle array and the single-layer graphene are combined, so that the strong SERS performance is achieved, the graphene is prevented from being damaged due to in-situ synthesis on the copper foil on which the graphene grows, and the integrity and the cleanness of the graphene are ensured.

Description

A silver triangular nanoparticle array/monolayer graphene film composite

technical field

The invention belongs to the technical field of graphene-based composite nanomaterials, and in particular relates to a silver triangular nanoparticle array/single-layer graphene film composite material and a preparation method thereof.

Background technique

Graphene has many excellent properties, such as good electrical and thermal conductivity, good toughness, and large specific surface area, which make graphene-based composites exhibit many excellent properties. For example, using graphene as a carrier to support nanoparticles can improve the catalytic, sensing, and energy storage properties of these particles. For example, in surface-enhanced Raman scattering (SERS) detection, the composite of graphene and noble metal nanostructures can make full use of the chemical enhancement of graphene itself and the physical enhancement of noble metals, as well as the large specific surface area and strong adsorption capacity of graphene, thereby improving the detection of molecules. concentration limit. It is well known that micron-scale graphene oxide sheets and their composites with noble metals have been extensively studied due to their easy chemical liquid-phase synthesis and large yields. However, the results show that the particles grown on graphene oxide are disordered, and the composites are generally powdery after drying, resulting in uneven SERS signals. So far, the use of chemical vapor deposition (CVD) to grow high-quality single-layer graphene films on copper foils has matured, providing a good choice for exploiting the advantages of graphene. However, the way to use this thin film is to use it as a device building unit through transfer, but for graphene with a thickness of only atomic level or several nanometers, it is inevitable to be polluted and damaged during the transfer process, which affects the performance of the device.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for controllably growing a triangular nanoparticle array on a single-layer graphene film.

The technical scheme for realizing the object of the present invention is: a silver triangular nanoparticle array/monolayer graphene film composite material and a preparation method thereof, the steps are as follows:

(1) CVD growth of single-layer graphene film on copper foil;

(2) A single-layer PS spherical colloid film was prepared on a glass slide;

(3) Transfer the single-layer PS ball colloid film to the copper foil grown with the graphene film film to obtain the single-layer PS ball template/graphene film/copper foil;

(4) Thermal evaporation was used to deposit silver on the single-layer PS sphere template/graphene film/copper foil, and the sample remained stationary during the deposition process;

(5) Removing the PS ball template after depositing silver, the single-silver triangular nanoparticle array/single-layer graphene film composite material can be obtained.

Preferably, atmospheric pressure CVD is used to grow a single-layer graphene film with copper foil as a substrate and a catalyst.

Specifically, firstly, the oxide layer on the surface of the copper foil is removed by annealing in a mixed atmosphere of hydrogen and argon, then methane is passed through, a single-layer graphene film is grown by CVD, and finally cooled to room temperature under the protection of argon.

Preferably, a single-layer PS sphere colloid film is prepared on a glass slide by using a gas-liquid-solid interface self-assembly method.

Specifically, PS spheres (diameter 1 μm) suspension (2.5 wt%) and ethanol were uniformly mixed by volume ratio 1:1 ultrasonically, take a clean glass slide, and use the gas-liquid-solid interface self-assembly on the glass slide Methods Monolayer PS spherical colloidal films were prepared.

Preferably, the glass slide carrying the single-layer PS spherical colloid film is slowly immersed in water at 45 ^° , and the single-layer PS spherical colloidal film is transferred to the copper foil grown with the graphene film film to obtain a single-layer PS spherical template. /graphene film/copper foil.

Preferably, the obtained single-layer PS sphere template/graphene film/copper foil is heated in an incubator to change the size of the triangular gap between the spheres.

Specifically, the heat treatment temperature is 110° C., and the time is less than 20 minutes.

Preferably, the silver is deposited by thermal evaporation, and the deposition thickness is 100 nm.

Preferably, the PS ball template after the silver deposition is removed by soaking in an organic solvent.

Specifically, the organic solvent is CH ₂ Cl ₂ , and the soaking time is 10 min.

Compared with the prior art, the innovation of the present invention has two points: (1) The composite material is new: the silver triangular nanoparticle array/monolayer graphene film composite material is unique in structure, combining the silver triangular nanoparticles The respective advantages of graphene and single-layer graphene and the synergistic effect of the two will have better optoelectronic properties than a single material. (2) New preparation method: in situ synthesis on the copper foil of growing graphene, which ensures the integrity and cleanliness of graphene.

The advantages of the present invention will be further illustrated in the following description of the drawings and the detailed description.

Description of drawings

FIG. 1 is a schematic diagram of the process route for preparing the silver triangular nanoparticle array/monolayer graphene film composite material according to the present invention.

Fig. 2 is the PS sphere template (a) with a diameter of 1 μm used in Example 1 of the present invention and the morphology (b) of the sample after vapor deposition of silver.

3 is the morphology of the silver triangular nanoparticle array/graphene film/copper foil prepared in Example 1 of the present invention.

FIG. 4 is the SERS spectrum of the R6G molecule of the silver triangular nanoparticle array/graphene film/copper foil in Example 1 of the present invention.

5 is the morphology of the silver triangular nanoparticle array/graphene film/copper foil prepared in Example 2 of the present invention.

Detailed ways

The silver triangular nanoparticle array/single-layer graphene film prepared by the invention, that is, the controllable growth of the silver triangular nanoparticle array on the single-layer graphene, combines the respective advantages of the silver triangular nanoparticle array and the single-layer graphene and the advantages of the two. synergistic effect, with strong SERS performance. Because it is synthesized in situ on the copper foil of growing graphene, the damage of graphene is avoided and its integrity and cleanliness are ensured.

The schematic diagram of the process route is shown in Figure 1. First, a single-layer graphene film was grown on the copper foil; second, a single-layer PS sphere template was assembled and transferred onto the single-layer graphene-attached copper foil; then, silver was deposited by thermal evaporation; finally, the PS spheres were removed The silver triangular nanoparticle array on the single-layer graphene film can be obtained. The structural parameters of the array can be regulated by process parameters.

Example 1

(1) CVD growth of single-layer graphene film. A copper foil (Alfa Aesar, 99.8%) with a thickness of 25 μm was placed in a tube furnace and annealed at 1000 °C for 30 min in a mixed atmosphere of hydrogen (100 sccm) and argon (300 sccm) to remove the surface oxides of the copper foil; Then, methane (10 sccm) was introduced, and after 30 min of growth, the hydrogen and methane were turned off and cooled to room temperature under the protection of argon, and a single-layer graphene film could be grown on the copper foil. (2) Synthesis of PS sphere template/monolayer graphene film/copper foil. PS sphere suspension (2.5 wt%) with a diameter of 1 μm and ethanol were ultrasonically mixed at a volume ratio of 1:1. An appropriate amount of deionized water was added to the clean glass slide to form a large-area thin-layer water film. About 0.1 mL of the PS sphere mixture was taken to the surface of the water film. The PS spheres spontaneously self-assembled into a large-area single-layer colloidal crystal film at the gas-liquid-solid interface. The glass slide was slowly immersed in water at 45°, the colloidal sphere film could float to the water surface, and was picked up with the copper foil on which the single-layer graphene film was grown. (3) Thermal evaporation deposition of silver 100 nm. The PS ball template was silver-plated by thermal evaporation, and the vacuum degree of the thermal evaporation equipment was maintained at 2×10 ^-4 Pa during silver plating. The sample remains stationary during deposition. (4) Finally, the silver-plated samples were soaked in CH ₂ Cl ₂ solvent for 10 min to remove the PS spheres, and the silver triangular nanoparticle arrays on the single-layer graphene were obtained.

The morphology and composition of the samples were characterized by S-4800 field emission scanning electron microscope (FESEM) from Hitachi, Japan, and the optical properties of the samples were analyzed by In Via laser confocal Raman spectrometer from Renishwa, UK.

Figure 2 shows the PS sphere template with a diameter of 1 μm in Example 1 of the present invention and the morphology of the PS sphere template after silver evaporation. Figure 2a shows the morphology of the PS sphere template before depositing silver, from which it can be seen that the PS spheres are closely arranged in a regular and orderly manner, and there are triangular gaps between the spheres. Figure 2b shows the morphology of the PS sphere template after depositing silver. It can be seen that the PS spheres are closely arranged in hexagonal shape, the surface of the PS sphere is a shell layer composed of silver nanoparticles, and silver nanoparticles are also deposited at the triangular gap.

3 is the morphology of the silver triangular nanoparticle array on the single-layer graphene film prepared in Example 1 of the present invention. Figure 3a shows the morphology of the silver triangular nanoparticle array obtained by removing the silver-deposited colloidal sphere template (Figure 2b). It can be observed from Figure 3a that after the removal of PS spheres, the triangular gaps between the original PS spheres formed silver triangular nanoparticle arrays after silver deposition, and the overall arrangement was uniform and orderly, and the side length of a single triangular particle was about 200 nm. Figure 3b is a high-magnification SEM image of the silver triangular nanoparticle array.

FIG. 4 is the SERS spectrum of the R6G molecule by the silver triangular nanoparticle array on the single-layer graphene in Example 1 of the present invention. Curves 1 and 2 correspond to the SERS spectra of silver triangular nanoparticle array/single-layer graphene film and continuous silver film (single-layer graphene/copper foil substrate, no PS sphere template, and the same thermal evaporation process parameters), respectively. It can be seen that silver The triangular nanoparticle array/single-layer graphene film substrate has a greater enhancement ability, which comes from two aspects: one is the combined enhancement of the large physical enhancement of silver triangular nanoparticles and the chemical enhancement of large graphene ( The second is that the π-π interaction between graphene and aromatic molecules containing benzene rings improves the adsorption capacity of such molecules.

Example 2

Other steps and process conditions are the same as in Example 1. The difference is that before step (3), the two single-layer PS sphere templates obtained in step (2) were heated at 110°C/10min and 110°C/20min, respectively, to obtain 110°C/10min. The morphology of silver triangular nanoparticle array/monolayer graphene film/copper foil (Figure 5a) and the morphology of silver triangular nanoparticle array/monolayer graphene film/copper foil under heating conditions of 110 °C/20min (Figure 5b) .

Comparing Fig. 5a and Fig. 5b, and in conjunction with Fig. 3, we can find that the heat treatment of the PS sphere template has a significant effect on the triangular size. also decreased. Therefore, the size of silver triangular nanoparticles can be regulated by changing the heating conditions of the PS sphere template before depositing silver.

According to the above research results, it is feasible to in-situ prepare triangular silver nanoparticle arrays on CVD-grown single-layer graphene films. The process has the advantages of no pollution, adjustable silver size, good reproducibility, and easy mass synthesis. Get practical. SERS test shows that this graphene-based composite has more excellent properties.

Claims (10)

1. a preparation method of silver triangular nanoparticle array/monolayer graphene film composite material, is characterized in that, its steps are as follows: (1) CVD growth of single-layer graphene film on copper foil; (2) A single-layer PS spherical colloid film was prepared on a glass slide; (3) Transfer the single-layer PS ball colloid film to the copper foil grown with the graphene film film to obtain the single-layer PS ball template/graphene film/copper foil; (4) Thermal evaporation was used to deposit silver on the single-layer PS sphere template/graphene film/copper foil, and the sample remained stationary during the deposition process; (5) Removing the PS ball template after depositing silver, the single-silver triangular nanoparticle array/single-layer graphene film composite material can be obtained. 2. method as claimed in claim 1, is characterized in that, on copper foil, CVD growth monolayer graphene film, concrete process is as follows: at first in hydrogen and argon mixed atmosphere, annealing removes copper foil surface oxide layer, then pass through. Into methane, a single-layer graphene film was grown by CVD, and finally cooled to room temperature under argon protection. 3 . The method of claim 1 , wherein a single-layer PS sphere colloid film is prepared on a glass slide by a gas-liquid-solid interface self-assembly method. 4 . 4. method as claimed in claim 3, is characterized in that, 2.5 wt% PS ball suspension and ethanol are uniformly mixed by volume 1:1 ultrasonic, get clean glass slide, adopt gas-liquid- Monolayer PS sphere colloidal films prepared by solid-phase interface self-assembly method. 5. method as claimed in claim 1, is characterized in that, the slide glass that is loaded with monolayer PS ball colloid film is slowly immersed in water with 45 ^° , and monolayer PS ball colloid film is transferred to grow with graphene film film On the copper foil, a single-layer PS sphere template/graphene film/copper foil was obtained. 6 . The method of claim 1 , wherein the obtained single-layer PS ball template/graphene film/copper foil is subjected to heat treatment. 7 . 7. The method of claim 6, wherein the heat treatment temperature is 110°C and the time is less than 20min. 8. The method of claim 1, wherein the silver is deposited by thermal evaporation, and the deposition thickness is 100 nm. 9 . The method of claim 1 , wherein the PS ball template after depositing silver is removed by soaking in an organic solvent. 10 . 10. The silver triangular nanoparticle array/monolayer graphene thin film composite material prepared by the method according to any one of claims 1-9.

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