CN100427381C - Diameter refinement method of one-dimensional micro-nanostructure materials of metal-organic complexes - Google Patents

Abstract

The invention is a new method for refining the diameter of one-dimensional micro-nano material-steam induced reaction method. Since the one-dimensional structure of the metal-organic complex (M-TCNQ) produced by the traditional solution chemical reaction method generally has a diameter of several micrometers, how to prepare its nanostructure by this method is a difficult problem. On the basis of the solution chemical reaction method, the present invention proposes a new preparation method-steam induced reaction method. The method is to first plate a layer of metal film with a nanometer thickness on the substrate by a conventional method; then immerse the metal nano film part into a hot TCNQ acetonitrile solution, and due to the induction of steam, nanobelts will be formed in the part of the metal nano film that is not immersed. , nanowires or micronanotubes. Compared with the traditional solution chemical reaction method, the generated one-dimensional structure has a smaller diameter and a longer length. The method has simple experimental equipment, controllable process and wide application range.

Description

Diameter refinement method of one-dimensional micro-nanostructure materials of metal-organic complexes

technical field

The invention relates to a preparation method of a one-dimensional nanometer material, which belongs to the field of chemical materials.

Background technique

Since the discovery of carbon nanotubes by Iijima (Ijima S.[J].Nature 1991 354:56) in 1991, various novel one-dimensional nanomaterials such as nanotubes, nanowires, nanorods, nanobelts and nanocoaxial cables have been developed. It has been discovered one after another and has aroused widespread international attention. They have their unique applications in mesoscopic physics and nano-device construction (Y.Xia, P.Yang, Y.Sun, et al.Adv.Mater.2003 15(5):353).

First discovered 7,7,8,8-tetracyanoquinodimethane (TCNQ) and Some charge-transfer complexes of electron donors have unique photoelectric properties, and the electrical, optical and photoelectric switching phenomena and their mechanisms of thin film devices have been studied in depth.

Since the metal-organic complex M-TCNQ has a high conductivity direction only along the direction of TCNQ columnar stacking, and is an insulating state in other directions, M-TCNQ is a quasi-one-dimensional conductor or semiconductor. Research on how to prepare the one-dimensional nanostructure of this metal-organic complex will lay the foundation for its application in nanoelectronic devices, but there is no such research report yet.

Contents of the invention

The object of the present invention is to obtain a method for refining the diameter of metal-organic complex one-dimensional micro-nano structure materials with simple method and good effect.

The specific steps for preparing the metal-organic complex one-dimensional micro-nanostructure by steam-induced solution chemical reaction method are as follows:

(1) prepare a layer of 5-20 nanometer thick metal film on the substrate with vacuum evaporation or sputtering;

(2) prepare 7,7,8,8-tetracyanoquinodimethane in small flask, i.e. TCNQ acetonitrile saturated solution,

Then place it in a hot water bath to keep the temperature of the TCNQ acetonitrile solution at 40-60°C;

(3) Partially immerse the metal film in the above-mentioned TCNQ acetonitrile solution. Under the action of water vapor and volatilized acetonitrile, the TCNQ molecules will climb to the part of the substrate that is not immersed in the solution, and chemical reactions will occur in the immersed and non-immersed parts. , to generate metal-organic complexes with one-dimensional micro-nano structures of different shapes.

(4) After reacting for 1-3 minutes, take out the sample and wash the residual substances on the sample.

In the present invention, the microtubes, nanotubes, nanowires/rods/bands and other structures of Ag-TCNQ and Cu-TCNQ prepared by steam induction method are examples, and the specific process is as follows (as shown in Figure 1):

1) First prepare a layer of Ag or Cu metal film with a thickness of 5-20 nanometers on the substrate by vacuum evaporation or sputtering;

2) Prepare a TCNQ acetonitrile saturated solution (3) in a small flask, and then place it in a hot water bath (1), so that the temperature of the TCNQ acetonitrile solution is maintained at 40-60°C;

3) The metal thin film is partially immersed in a hot TCNQ acetonitrile solution. Under the action of water vapor and volatilized acetonitrile, the TCNQ molecules will climb to the part of the substrate that is not immersed in the solution. Therefore, chemical reactions will occur in the immersed and non-immersed parts, thereby generating Ag-TCNQ or Cu-TCNQ with different morphologies;

4) After reacting for 1-3 minutes, take out the sample and put it into an acetonitrile solution to wash away the residual substances on the sample.

The present invention forms three regions in the TCNQ acetonitrile solution immersed in the metal film part: the immersed part is a thermal reaction zone (4); the critical surface where the film is immersed in the TCNQ acetonitrile solution is a transition zone (5) and the non-immersed part is an induced reaction zone (6) ). Through the SEM test, the main appearances are: micron tubes generated in the Ag-TCNQ thermal reaction zone (as shown in Figure 2); Ag-TCNQ induced micro-nanotubes generated in the reaction zone (as shown in Figure 3, with a diameter of about 400nm; Fig. 4 shows a longer tube with a length of about 50 microns) and the diameter of nanorods (as shown in Figure 5); the cored microtubes generated in the Cu-TCNQ thermal reaction zone (as shown in Figure 6); Cu- The cross-section of the TCNQ transition region is a square nanorod (as shown in Figure 7, with a diameter of 200-400nm); the Cu-TCNQ-induced reaction region generates a nanoribbon (as shown in Figure 8, with a diameter of about 100nm). It can be seen that the diameter of the sample prepared in the transition zone and the induced reaction zone is smaller, which plays a role in refinement.

The metal used in the present invention must be the metal that can react with TCNQ oxidation-reduction, as Ag, Cu, K, Na etc., but preferably with Ag, Cu.

When washing in the present invention, it is better to use acetonitrile solution, which can dissolve the residual TCNQ left on the substrate surface, and the dissolution of Ag-TCNQ and Cu-TCNQ in acetonitrile is very small.

The mechanism of the thinner metal-organic complex one-dimensional micro-nano structure prepared by the steam-induced reaction method used in the present invention is explained as follows: because the TCNQ solution is placed in a hot water bath, water vapor evaporates and condenses on the metal film without entering On the surface of the part of the film in the solution, TCNQ "climbs" to it along the channels of these water films. Because metal is a good electron donor; and TCNQ is a good electron acceptor, so metal, TCNQ and water form a galvanic battery structure, in which the metal is the anode; TCNQ is the cathode. Although the concentration of TCNQ in this part of the region is lower than that of the saturated solution, the electrochemical reaction occurs due to the presence of water, thus accelerating the formation of M-TCNQ. As a result, the speed of nucleation and growth is faster than normal, and the diameter is refined. At the same time, due to the different concentration distribution of TCNQ, the size of nucleation is different. In general, the nucleation size of the induced region with a lower concentration is smaller, so it is beneficial to the diameter refinement to a certain extent. Generally, strip-shaped and linear micro-nano-structure materials are generated in the induction reaction zone, rod-shaped micro-nano-structure materials are generated in the transition zone, and tubular micro-nano-structure materials are generated in the thermal reaction zone.

The method of the invention is simple and easy to operate, and the strips, wires, rods and tubular materials obtained in each reaction zone are very satisfactory.

Description of drawings

Figure 1 is a schematic diagram of the experimental device for the steam-induced reaction method.

Figure 2 is a diagram of microtubes formed in the thermal reaction zone of Ag-TCNQ.

Figure 3 is a diagram of the micro-nanotubes generated in the Ag-TCNQ-induced reaction zone.

Figure 4 is a diagram of longer micro-nanotubes generated in the Ag-TCNQ-induced reaction zone.

Figure 5 is a diagram of the nanorods generated in the Ag-TCNQ-induced reaction zone.

Fig. 6 is a diagram of a cored microtube formed in the thermal reaction zone of Cu-TCNQ.

Fig. 7 is a diagram of nanorods with a square cross-section generated by the Cu-TCNQ transition region.

Figure 8 is a diagram of the nanobelts formed in the Cu-TCNQ-induced reaction zone.

In the above figure, 1 is a hot water bath; 2 is a metal film; 3 is a TCNQ saturated solution; 4 is a thermal reaction zone; 5 is a transition zone; 6 is an induced reaction zone.

Detailed ways

Embodiment 1: Preparation of Ag-TCNQ micro-nanostructure sample

First, the Si substrate is cleaned; then a 10nm-thick Ag film is evaporated by vacuum evaporation. The purity of the silver wire used is 99.999%, the vacuum degree during evaporation is 1×10 ^-3 Pa, the deposition rate is 0.1nm/s, and the thickness of the evaporation is monitored in real time by a film thickness measuring instrument; TCNQ acetonitrile is prepared in a small flask Saturate the solution, and then place it in a hot water bath in a large flask to keep the temperature of the TCNQ acetonitrile solution at about 40°C; immerse the Ag film part in the hot TCNQ acetonitrile solution, under the action of water vapor and volatilized acetonitrile Under this condition, TCNQ molecules will climb to the part of the substrate that is not immersed in the solution. Therefore, chemical reactions will occur in the immersed and non-immersed parts, thereby forming Ag-TCNQ with different shapes; after 1 min of reaction, take out the sample and put it into the acetonitrile solution to wash away the residual substances on the sample.

The SEM photographs of the obtained samples are shown in Figures 2, 3, 4, and 5.

Embodiment 2: Preparation of Cu-TCNQ micro-nanostructure sample

First, the Si substrate is cleaned; then a layer of Cu film with a thickness of 20nm is evaporated by vacuum evaporation. The purity of the copper block used is 99.99%, the vacuum degree during evaporation is 1×10 ^-3 Pa, the deposition rate is 0.1nm/s, and the thickness of the evaporation is monitored in real time by a film thickness measuring instrument; TCNQ acetonitrile is prepared in a small flask Saturate the solution, and then place it in a hot water bath in a large flask to keep the temperature of the TCNQ acetonitrile solution at about 60°C; immerse the Cu film part in the hot TCNQ acetonitrile solution, under the action of water vapor and volatilized acetonitrile Under this condition, TCNQ molecules will climb to the part of the substrate that is not immersed in the solution. Therefore, chemical reactions will occur in the immersed and non-immersed parts, thereby forming Cu-TCNQ with different shapes; after 3 minutes of reaction, take out the sample and put it into the acetonitrile solution to wash away the residual substances on the sample.

The SEM photographs of the obtained samples are shown in Figures 6, 7 and 8.

Claims (2)

1. A method for refining the diameter of a one-dimensional micro-nano structure of a metal-organic complex, characterized in that it is a steam-induced solution chemical reaction method, and the specific steps are as follows: (1) prepare a layer of 5-20 nanometer thick Ag or Cu metal film on the substrate with vacuum evaporation or sputtering; (2) Prepare 7,7,8,8-tetracyanoquinodimethane, i.e. a saturated solution of TCNQ in acetonitrile, and then place it in a hot water bath so that the temperature of the TCNQ acetonitrile solution is maintained at 40-60°C; (3) Partially immerse the Ag or Cu metal film in the above-mentioned TCNQ acetonitrile solution. Under the action of water vapor and volatilized acetonitrile, the TCNQ molecules will climb to the part of the substrate that is not immersed in the solution, and the immersed and non-immersed parts will A chemical reaction occurs to generate metal-organic complexes with one-dimensional micro-nano structures of different shapes; (4) After reacting for 1-3 minutes, take out the sample and wash the residual substances on the sample. 2. The method according to claim 1, characterized in that acetonitrile solution is used for washing.

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