CN111636065B

CN111636065B - Silver triangular ring nanoparticle array/single-layer graphene film composite material and preparation method thereof

Info

Publication number: CN111636065B
Application number: CN202010410212.2A
Authority: CN
Inventors: 何辉; 程建祥; 范璐瑶; 杨金彭; 曾祥华
Original assignee: Yangzhou University
Current assignee: Yangzhou University
Priority date: 2020-05-15
Filing date: 2020-05-15
Publication date: 2022-06-07
Anticipated expiration: 2040-05-15
Also published as: CN111636065A

Abstract

The invention discloses a silver triangular ring nanoparticle array/single-layer graphene film composite material and a preparation method thereof, and the preparation method 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 the sample keeps rotating at a constant speed in the deposition process; and finally, removing the PS spheres to obtain the silver triangular ring nanoparticle array on the single-layer graphene film. According to the invention, the silver nano-ring particle array can be controllably grown on the single-layer graphene, the respective advantages of the silver nano-ring array and the single-layer graphene and the synergistic effect of the silver nano-ring array and the single-layer graphene are combined, the excellent SERS performance is achieved, meanwhile, the silver nano-ring particle array is synthesized in situ on the copper foil for growing the graphene, the damage of the graphene is avoided, and the integrity and the cleanness of the graphene are ensured.

Description

Silver triangular ring nanoparticle array/single-layer graphene film composite material and preparation method thereof

Technical Field

The invention belongs to the field of preparation of graphene-based composite nano materials, and particularly relates to a silver triangular ring nanoparticle array/single-layer graphene film composite material and a preparation method thereof.

Background

The graphene is a novel carbon nano material, has unique physical and chemical properties, and has a very wide application prospect. The two-dimensional plane of the graphene provides a good platform for constructing a device, and the device performance can be further improved through the synergistic effect of the graphene and other materials after the graphene and other materials are compounded. Due to the huge application potential in the fields of sensing, catalysis, photoelectron and the like, the graphene-based composite material has attracted extensive research interest. For example, Surface Enhanced Raman Scattering (SERS) detection, the graphene and precious metal nano composite structure can fully utilize chemical enhancement of graphene, large physical enhancement of precious metal, large specific surface area and strong adsorption capacity of graphene, so that the concentration limit of detection molecules is improved.

The micron-sized graphene oxide sheet synthesized by the chemical liquid phase method and the composite material thereof are widely researched, however, particles growing on the graphene oxide are disordered, and the composite material is generally powdery after being dried, so that some applications such as SERS (surface enhanced Raman scattering) are influenced. At present, a CVD (chemical vapor deposition) process for preparing a continuous graphene film is mature, and a good choice is provided for exerting the advantages of graphene materials. However, the graphene film is usually used to prepare a composite material or a device by a transfer method, i.e. it is transferred onto other substrates (such as a silicon wafer, some nanostructures, etc.), which inevitably causes pollution and damage to the graphene during the transfer process, and reduces the device performance.

Disclosure of Invention

The invention aims to provide an in-situ controllable growth triangular ring silver nanoparticle array on a single-layer graphene film and a method thereof.

The technical scheme for realizing the purpose of the invention is as follows: a silver triangular ring nanoparticle array/single-layer graphene film composite material and a preparation method thereof mainly comprise the following steps:

(1) growing a single-layer graphene film on a copper foil by CVD;

(2) preparing a single-layer PS ball colloid film on a glass slide;

(3) transferring the single-layer PS ball colloid film to a copper foil on which a graphene film grows to obtain a single-layer PS ball template/the graphene film/the copper foil;

(4) depositing silver on the single-layer PS spherical template/graphene film/copper foil by thermal evaporation, wherein the sample keeps rotating at a constant speed in the deposition process;

(5) and removing the PS spherical template after silver deposition to obtain the silver triangular ring nanoparticle array/single-layer graphene film composite material.

Preferably, the single-layer graphene film is grown by using the copper foil as a substrate and a catalyst by using normal-pressure CVD.

Specifically, annealing in a hydrogen and argon mixed atmosphere to remove an oxide layer on the surface of the copper foil, introducing methane, growing a single-layer graphene film by CVD, and cooling to room temperature under the protection of argon.

Preferably, a gas-liquid-solid phase interface self-assembly method is adopted to prepare the monolayer PS ball colloid film on the glass slide.

Specifically, a suspension (2.5 wt%) of PS spheres (with the diameter of 1 μm) and ethanol are ultrasonically and uniformly mixed according to the volume ratio of 1:1, a clean glass slide is taken, and a single-layer PS sphere colloid film is prepared on the glass slide by adopting a gas-liquid-solid phase interface self-assembly method.

Preferably, the slide glass loaded with the single-layer PS ball colloid film is slowly heated to 45 DEG^°And (3) immersing the single-layer PS spherical colloid film into water, and transferring the single-layer PS spherical colloid film onto a copper foil on which a graphene film grows 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 subjected to heating treatment by adopting a thermostat so as to change the size of a triangular gap between spheres.

Specifically, the heating treatment temperature is 110 ℃, and the time is less than 20 min.

Preferably, the silver is deposited by thermal evaporation to a thickness of 100 nm.

Preferably, the sample keeps rotating at a constant speed in the deposition process, and the rotating speed is 10r/min to 90r/min, and more preferably 30 r/min.

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

Specifically, the organic solvent is CH₂Cl₂The soaking time is 10 min.

Compared with the prior art, the innovation of the invention is as follows: (1) the prepared silver triangular ring nanoparticle array/single-layer graphene composite material is unique in structure, combines the synergistic effect of the silver triangular ring and the single-layer graphene, and has better photoelectric performance than that of a single material. (2) The nano structure is prepared in situ on the copper foil for growing the single-layer graphene, so that the transfer and damage to the graphene are avoided.

The advantages of the invention are further illustrated in the following figures and detailed description.

Drawings

Fig. 1 is a schematic process route of preparing a silver triangular ring nanoparticle array/single-layer graphene film composite material according to the present invention.

FIG. 2 shows the morphology (b) of a 1 μmPS-diameter spherical template (a) and its silver evaporated sample used in example 1 of the present invention.

Fig. 3 shows the morphology of the silver nanoring particle array/single-layer graphene film/copper foil prepared in example 1 of the present invention.

Fig. 4 is a SERS spectrum of a pair of R6G molecules, namely, a silver nanoring particle array/single-layer graphene film/copper foil, in example 1 of the present invention.

Fig. 5 shows the morphology of the silver nanoring particle array/single-layer graphene film/copper foil prepared in example 2 of the present invention.

Detailed Description

The silver nano-ring particle array/single-layer graphene film prepared by the invention is a controllable silver nano-ring particle array growing on single-layer graphene, combines the respective advantages of the silver nano-ring array and the single-layer graphene and the synergistic effect of the silver nano-ring array and the single-layer graphene, has excellent SERS performance, is synthesized in situ on a copper foil growing graphene, avoids the damage of the graphene, and ensures the integrity and the cleanness of the graphene.

The process scheme is schematically shown in figure 1. Firstly, 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 a single-layer graphene film; then, depositing silver by thermal evaporation, wherein the sample keeps rotating at a constant speed in the deposition process; and finally, removing the PS spheres to obtain the silver triangular ring nanoparticle array on the single-layer graphene film. The structural parameters of the array can be regulated and controlled through process parameters.

Example 1

(1) CVD grows single layer graphene films. Copper foil (Alfa Aesar, 99.8%) with a thickness of 25 μm was used as a catalyst and a substrate, and placed in the middle of a tube furnace, and annealed at 1000 ℃ for 30 min in a mixed atmosphere of argon (300 sccm) and hydrogen (100 sccm) to remove an oxide layer on the surface of the copper foil; then introducing methane (10 sccm) for growth for 30 min, and closing hydrogen and methane to cool to room temperature under the protection of an argon atmosphere. (2) Assembling the PS spherical template/the single-layer graphene film/the copper foil. Of diameter 1 μmUniformly ultrasonically mixing a PS ball suspension (2.5 wt%) and ethanol according to the volume ratio of 1:1, adding a proper amount of deionized water on a clean glass slide to form a large-area thin-layer water film, taking about 0.1 mL of PS ball mixed solution to the surface of the water film, automatically self-assembling PS balls on a gas-liquid-solid interface to form a single-layer colloidal crystal film with the square centimeter magnitude, slowly immersing the glass slide into water at 45 degrees, floating the colloidal crystal film to the water surface, taking out the colloidal crystal film by using a copper foil for growing graphene, and baking a PS ball template for 10 min at 110 degrees. (3) Thermal evaporation deposits the silver. The thermal evaporation is adopted to deposit silver on the PS spherical template by 100 nm, and the vacuum degree of thermal evaporation equipment is maintained at 2 multiplied by 10 during silver deposition^-4pa. The sample is kept rotating at a constant speed (30 r/min) during the deposition process. (4) And (5) removing the template. Soaking the silver-deposited sample in CH₂Cl₂And removing the PS spheres in the solvent for 10 min to obtain the silver triangular ring nanoparticle array on the single-layer graphene film.

The morphology of the sample was observed using a S-4800 Field Emission Scanning Electron Microscope (FESEM) from Hitachi, Japan, and the optical properties of the sample were analyzed using an In Via laser confocal Raman spectrometer from Renishwa, UK.

FIG. 2 shows the shapes of the PS sphere template with a diameter of 1 μm and the PS sphere template after silver evaporation in example 1. FIG. 2a shows the shape of a PS sphere template before silver deposition, the colloidal spheres are regularly arranged as a whole, and triangular gaps are formed among the colloidal spheres. And fig. 2b shows the morphology of the PS sphere template after silver deposition, colloidal spheres are in hexagonal close arrangement, and the PS sphere shell layer is coated with silver nanoparticles and has a rough surface.

Fig. 3 shows the morphology of a silver triangular ring nanoparticle array on a single-layer graphene film prepared in example 1 of the present invention. Fig. 3a is the silver nanoring array morphology resulting from the removal of the colloidal sphere template (fig. 2 b) after the deposition of silver. From fig. 3a it can be observed that after removal of the colloidal sphere shell, the array is composed of nanoparticles with regular triangular outer perimeter (about 300 nm side length) and circular inner perimeter (about 100 nm diameter), and the array has a very regular periodicity.

Fig. 4 is a SERS spectrum of the silver triangular ring nanoparticle array on the single-layer graphene film according to example 1 of the present invention for R6G molecules.

Curves

1 and 2 correspond to SERS spectra of silver triangular ring nanoparticle arrays and silver triangular ring nanoparticle arrays on silicon wafers (without single layer graphene), respectively. The results show that both substrates have great enhancement effect, and the silver triangular ring nanoparticle array has great physical enhancement in reaction, and the enhancement comes from two aspects: firstly, the ring structure has nanometer-scale gaps, which is an enhanced 'hot spot'; and secondly, the array periodic structure can couple the optical field and increase the Raman scattering cross section. Compared with two substrates, the silver nano-ring particle array/single-layer graphene film has a better enhancement effect, the reacted graphene plays a role in the enhancement effect, and the role also has two aspects: firstly, graphene has large chemical enhancement capability and can be enhanced in combination with large physical enhancement of silver particles (the two are in a multiplication relation to enhancement factors); and secondly, the graphene can improve the adsorption capacity of aromatic molecules containing benzene rings through pi-pi interaction.

Example 2

Other steps and process conditions were the same as in example 1. The difference is that the two single-layer PS sphere templates obtained in step (2) are respectively subjected to non-heating treatment and heating treatment at 110 ℃/20min to obtain the morphology of silver triangular ring nanoparticle array/single-layer graphene film/copper foil under the non-heating treatment condition (fig. 5 a) and the morphology of silver triangular ring nanoparticle array/single-layer graphene film/copper foil under the heating condition at 110 ℃/20min (fig. 5 b).

Comparing fig. 5a and 5b, together with fig. 3, we found that heat treatment of the PS sphere template prior to silver deposition had a significant effect on the size of the nanorings. The heat treatment time is long, the outer circumference of the triangular ring becomes small, the shape of the triangular ring is changed to be nearly circular, and the inner circumference of the triangular ring becomes large. Mechanism of formation of triangular ring: in the thermal evaporation process, silver atoms do linear motion, and the silver atoms are deposited on the surfaces of the graphene exposed at the triangular gaps, so that the periphery of the triangular ring is triangular; meanwhile, a circular ring is formed due to sample rotation and shadow effect; the PS balls are heated for a long time, the triangular gaps among the balls are reduced to reduce the length of the outer peripheral edge of the triangular ring, and meanwhile, the shadow effect is increased to enlarge the circular ring.

From the above results, it can be seen that: the method for synthesizing the nanoparticle array in situ on the single-layer graphene film grown by the CVD process is feasible, the process combines the respective advantages of the single-layer graphene and the periodic metal nanoparticle array, and SERS tests show that the graphene-based composite material has more excellent performance; meanwhile, the preparation process is pollution-free and has good repeatability, can be used for large-area synthesis, and is expected to be further applied to the practice.

Claims

1. A preparation method of a silver triangular ring nanoparticle array/single-layer graphene film composite material is characterized by mainly comprising the following steps:

(1) growing a single-layer graphene film on a copper foil by CVD;

(2) preparing a single-layer PS ball colloid film on a glass slide;

(4) heating the obtained single-layer PS spherical template/graphene film/copper foil; the heating treatment temperature is 110 ℃, the time is less than 20min, the silver is deposited on the single-layer PS spherical template/graphene film/copper foil by thermal evaporation, the sample keeps rotating at a constant speed in the deposition process, and the rotating speed is 10 r/min-90 r/min;

2. The method of claim 1, wherein the copper foil is first annealed in a mixed atmosphere of hydrogen and argon to remove an oxide layer on the surface of the copper foil, then methane is introduced, a single-layer graphene film is grown on the copper foil by CVD, and finally the copper foil is cooled to room temperature under the protection of argon.

3. The method of claim 1, wherein the monolayer PS sphere colloid film is prepared on the glass slide using a gas-liquid-solid phase interface self-assembly method.

4. The method of claim 1, wherein 2.5wt% PS sphere suspension and ethanol are ultrasonically mixed uniformly in a volume ratio of 1:1, a clean glass slide is taken, and a monolayer PS sphere colloid film is prepared on the glass slide by a gas-liquid-solid phase interface self-assembly method.

5. The method of claim 1, wherein the slide bearing the monolayer of PS bead colloidal film is slowly ramped at 45 degrees celsius^°And (3) immersing the single-layer PS spherical colloid film into water, and transferring the single-layer PS spherical colloid film onto a copper foil on which a graphene film grows to obtain a single-layer PS spherical template/graphene film/copper foil.

6. The method of claim 1, wherein the silver is deposited by thermal evaporation to a thickness of 100 nm.

7. The method of claim 1, wherein the sample is kept rotating at a constant speed during the deposition process, wherein the rotation speed is 30 r/min.

8. The silver triangular ring nanoparticle array/single-layer graphene thin film composite material prepared by the method of any one of claims 1-7.