CN1195103C - Process for electrochemically preparing nanoline array of Fullerenes - Google Patents

Abstract

The electrochemical preparation technology of fullerene nanowire arrays is mainly as follows: first, the toluene solution of fullerene is added to a certain proportion of acetonitrile solution to form negatively charged fullerene aggregates, and then the electrochemical method is used to make The aggregates are electrophoresed into the nanopores of the porous template, thereby forming an ordered array of fullerene nanowires. The diameter of the nanowires can be regulated by the pore size of the porous template used, the length can be controlled by the concentration of the electrolyte and the deposition time, and the crystal structure can be improved by annealing. By using the invention, not only fullerene nanowires with controllable diameter and length can be prepared, but also highly ordered nanowire arrays can be obtained.

Description

Electrochemical Preparation Technology of Fullerene Nanowire Arrays

technical field

The invention relates to the preparation of fullerene nanowires, in particular to the electrochemical preparation technology of highly ordered and diameter-controllable fullerene nanowire arrays.

Background technique

Materials, energy and information are the backbone of modern society and the main concerns of the new century. The development of new materials may become a new economic growth point, which determines or affects the development of an industry to a large extent.

One-dimensional nanomaterials (nanowires, nanotubes) refer to linear nanomaterials whose diameter is at the nanoscale (1-100 nm) and whose length is at the micron level or longer. It not only has huge potential application prospects in electronics, optics, mechanics and other devices, but also has far-reaching significance for basic research in the fields of chemistry, physics, electronics, optics, material science and biological science due to its unique properties.

Fullerenes are an important class of functional materials. Their photophysics, electrical conductivity, photoconductivity and light-limiting behavior have aroused great interest of scientists, but the difficulty of assembling them into ordered structures limits their applications. Therefore, it is of great significance to develop the preparation technology of ordered fullerene nanowire arrays.

In the current existing technology, the methods for preparing nanowires can be generally divided into physical methods (including laser ablation method, evaporation condensation method, arc discharge method, etc.) chemical methods (including chemical vapor deposition method, solution reaction method, template method, etc.) etc.) and the combined approach. For example, the laser ablation method is to use laser to evaporate the atoms of materials (Si, Ge, etc.), and then directional growth under the catalysis of nanoparticles (such as Au, Fe, etc.) to form nanowires. Due to the complex equipment and high cost of the physical synthesis method, and the size and shape of the prepared one-dimensional nanomaterials are not easy to control, orderly arrays cannot be obtained. Therefore, the current physical synthesis method is only used in carbon nanotubes, Si, _SiO In addition to showing certain advantages in the preparation of a few one-dimensional nanomaterials, it is rarely used in the preparation of other one-dimensional nanomaterials.

The preparation of one-dimensional nanomaterials mainly adopts chemical synthesis methods, and template synthesis methods are often used in chemical synthesis methods. The key technology is to use materials with one-dimensional nanopores (porous anodized aluminum oxide membranes, polymer filter membranes, etc.) As a template, the material enters the template hole through chemical, electrochemical methods or high temperature and high pressure conditions, and the hole wall of the template will limit the shape and size of the deposited material, and one-dimensional nanowires that replicate the shape of the hole can be produced. If a material with uniform pore diameter and regular arrangement is selected as a template, a nanowire array with uniform diameter and high order can be prepared.

Martin et al. have done a lot of pioneering work in this area. In 1987, they prepared Pt nanowire arrays for the first time using polycarbonate filter membrane as a template; in 1989, they synthesized Au nanowires in the channels of anodized aluminum template. Since then, they have extended this template synthesis method to the preparation of other one-dimensional nanomaterials, and achieved gratifying results. For example, nanotubes and nanowires of conductive polymer polypyrrole were prepared using polycarbonate filter membrane as a template, and Au nanotubes were prepared by introducing molecular anchor groups into anodized aluminum templates.

Following the work of Martin et al., the use of one-dimensional nanopore template synthesis to prepare one-dimensional nanostructured materials has been carried out rapidly. At present, noble metals Au, Pt, Ag, magnetic metals Ni, Fe, Co, layered magnetic metals Co/Cu, semiconductors CdS, Se, Te, GaSb, Bi ₂ Te ₃ , CdSe, CdS _x Se _{1- x} , Zn _x Cd _1-x S, GaAs, MnO ₂ nanowires, polymers polystyrene (PS), polymethyl methacrylate (PMMA), polyvinylidene fluoride, p-polyphenylene oxide, conductive polymers Polyaniline, poly-3-methylthiophene, polyacetylene, nanotubes and nanowires of inorganic simple substance C, and coaxial C/PAN/Au, Au/PPO/PPy, TiS ₂ /Au, PPy/LiMn ₂ O ₄ , Composite nanotubes or nanowires of TiO ₂ /PPy, PS/PPy, etc. These research results show that the one-dimensional nanopore template synthesis method is simple and universally applicable in the preparation of one-dimensional nanostructured materials.

However, due to the limitation of the solubility of fullerenes, it is difficult to fill them into the pores of the template by general methods. The preparation of fullerene nanowires and their arrays by the channel template method has not been reported yet.

Contents of the invention

The purpose of the present invention is to provide an electrochemical preparation technology of fullerene nanowire arrays, which is simple and easy to prepare highly ordered and diameter-controllable fullerene nanowire arrays under common experimental conditions.

In order to achieve the above object, the present invention mainly realizes the preparation of the fullerene nanowire array according to the following steps:

First, plate a conductive layer with a thickness of about several hundred nanometers on one side of the porous template to form an electrode, then fix the electrode on the template on the surface of the other electrode, and expose the other side of the template to the electrolyte to form a working electrode; Use another conductive material as the counter electrode; the electrolytic cell is made of Teflon or glass, and the anode and cathode are separated by a Teflon or glass barrier in the middle. Take the toluene solution of fullerenes and add it to 4-12 times the volume of acetonitrile, the mixed solution is yellowish brown, adjust the final concentration of fullerenes to 20-40 μM. Before electrophoretic deposition, the electrolyte solution is transferred to the electrolytic cell, and the constant voltage deposition is carried out at 20~400V, the template electrode is used as the anode, and the deposition time is 1~30min. After the deposition, the working electrode was taken out from the electrolytic cell, rinsed several times with a large amount of acetonitrile, and dried naturally. The fullerene nanowire array prepared according to the above steps is wrapped by the template and can be removed as needed. The crystal structure of nanowires can be improved by annealing.

The invention uses fullerene substances as reactants, and can prepare other nanowires, nanostructures or nanodevices through electrochemical methods and on the basis of porous templates.

The present invention has the following characteristics:

1. The present invention utilizes the characteristics that fullerenes can form negatively charged aggregates (clusters) in toluene and acetonitrile mixed solvents, and adopts electrochemical methods to electrophoresis these aggregates into nano template holes at room temperature, Therefore, the utility model has the advantages of simplicity and economy, low energy consumption, convenient operation and large adjustable range.

2. The diameter of the fullerene nanowire is determined by the pore size of the template. Therefore, the present invention can be used to prepare fullerene nanowires whose diameter can be adjusted within a wide range. In addition, the length of fullerene nanowires can be controlled by electrolyte concentration and deposition time.

3. By using materials with uniform pore size and regular arrangement as the template, nanowire arrays with uniform diameter and high order can be prepared, which lays the foundation for the construction of nanodevices.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing, wherein:

Fig. 1 is a device schematic diagram of the present invention;

Figure 2 is a schematic diagram of the composition of the template electrode in Figure 1;

3 is a schematic diagram of the growth of fullerene nanowire arrays of the present invention;

Fig. 4 is the AFM photograph of the porous anodized aluminum template that the embodiment of the present invention adopts;

Fig. 5 is the SEM photograph of the _C60 nanowire array prepared by the embodiment of the present invention;

Fig. 6 is the height of the AFM photo and cross-sectional analysis of the C ₆₀ nanowire array prepared in the embodiment of the present invention.

Detailed ways

As shown in Figure 1, fullerene electrolyte 2 is transferred in the electrolytic cell 1 made by polytetrafluoroethylene (Teflon), and the solvent of electrolyte is toluene/acetonitrile=1/4-12 volume ratio; 4 is the counter electrode (negative pole); the working electrode is a template electrode 5 fixed on the conductive substrate, and its composition is shown in Figure 2; the two electrodes are separated by a Teflon separator; when 20-400V is applied at both ends of the electrode, the negatively charged The fullerene aggregates are electrophoresed into the pores of the nano template under the action of an electric field to form nanowires, as shown in Figure 3; the deposition time is 1-30min; Rinse several times, and then dry naturally; that is, to make nanowires consistent with the channels of the template.

Example:

First, a layer of Ag is vacuum-deposited on one side of the porous anodized aluminum template as an electrode with a thickness of about 200 nanometers; then the Ag-plated electrode of the template is fixed on the surface of conductive glass, and the other side of the template is exposed to the electrolyte. Form the working electrode; use another conductive glass as the counter electrode, soak it with 0.1molL ^-1 NaOH for 1 hour before use, wash it ultrasonically for 30 minutes, soak it in acetone for 2 hours, rinse it with distilled water, and dry it naturally for later use; electrolysis The pool is made of Teflon or glass, with a volume of about 10ml, and the anode and cathode are separated by a Teflon or glass barrier in the middle.

The toluene solution of fullerene was added to 10 times the volume of acetonitrile, the mixed solution was yellowish brown, and the final concentration of fullerene was adjusted to 30 μM. Before electrophoretic deposition, the electrolyte solution was transferred to an electrolytic cell, and a constant voltage deposition was performed at 200V, and the template electrode was used as an anode, and the deposition time was 10 min. After the deposition, the working electrode was taken out from the electrolytic cell, rinsed several times with a large amount of acetonitrile, and then dried naturally.

Heat treatment is carried out in a tube furnace. Under the protection of argon atmosphere, heat from room temperature to 350 °C (heating rate is about 50 °C/min), stop heating after constant temperature for 3 hours, and let it stand at room temperature to cool.

Referring to Figure 4, since the selected porous anodized aluminum template is a hexagonal columnar body (Cell) with a round hole (Pore) in the center, it is a vertical hole array arranged in a hexagonal honeycomb shape. Therefore, using it as a template to obtain a parallel Arrays of ordered fullerene nanowires. Porous anodized alumina templates can be removed with 1M NaOH solution as needed. Figure 5 is the SEM photo of the obtained C ₆₀ nanowire array, it can be seen that the diameter of the nanowires is uniform and arranged in parallel, and the length is about 19 μm. Figure 6 is an AFM photo of C ₆₀ nanowires dispersed on the surface of mica, and its cross-sectional analysis shows that its height (representing the diameter of the nanowire) is 41 and 47 nm, which is consistent with the aperture of the template used.

It should be noted that the above-mentioned embodiments are only used to illustrate the technical characteristics of the present invention, and are not used to limit the scope of patent application of the present invention. For example, the porous anodized aluminum template in this embodiment can also use polymer filter membranes, etc. Principle still belongs to the scope of patent application of the present invention.

Claims (6)

1. An electrochemical preparation technology for a fullerene nanowire array, the main steps of which are: Plate a continuous conductive layer with a thickness of several nanometers on one side of the non-conductive porous template with a pore size of several nanometers to hundreds of nanometers to form an electrode, fix the electrode on a conductive base, and expose the other side of the template to the electrolyte, Form the working electrode; Using another conductive material as an auxiliary electrode; Put the working electrode and the auxiliary electrode in the electrolytic cell made of polytetrafluoroethylene or glass after separating them with polytetrafluoroethylene or glass; Add the toluene solution of fullerene to 4-12 times the volume of acetonitrile solution to form an electrolyte solution of negatively charged fullerene aggregates; adjust the final concentration of fullerene to 20-40 μM; Transfer the electrolyte solution to the electrolytic cell, and conduct constant voltage deposition at 20-400V, the template electrode is used as the anode, and the deposition time is 1-30min; the fullerene aggregates are electrophoresed into the nanopores of the porous template, thereby forming rich Arrays of strene nanowires; The working electrode was removed from the electrolytic cell, rinsed with acetonitrile and dried. 2. The electrochemical preparation technology of fullerene nanowires according to claim 1, characterized in that the conductive base and auxiliary electrodes are conductive metal, inorganic or organic materials. 3. The electrochemical preparation technology of fullerene nanowires according to claim 1, characterized in that the fullerenes include fullerene derivatives. 4. The electrochemical preparation technology of fullerene-based nanowires according to claim 1, characterized in that the fullerene-based nanowires include electrochemical methods using fullerene-based substances as one of the reactants , other nanowires, nanostructures or nanodevices prepared on the basis of porous templates. 5. The electrochemical preparation technology of fullerene nanowires according to claim 1, characterized in that the conductive coating on the nanoporous template is metal or other conductive materials, and vacuum evaporation, sputtering, etc. method. 6. The electrochemical preparation technology of fullerene nanowires according to claim 1, characterized in that the crystal structure and properties of the fullerene nanowires are improved by annealing.

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