TWI464108B - The preparation of porous silicon nanowires and the prepared porous silicon nanowires - Google Patents

Description

Method for preparing porous tantalum nanowire and prepared porous nanowire

The invention relates to a method for preparing a nanowire, in particular to a method for preparing a porous nanowire and a porous nanowire prepared.

The nanowire is a semiconductor material with a very high aspect ratio. Among the various types of nanowires, porous nanowires have nanometer-scale porous structure characteristics, and are used in photovoltaic elements, photocatalysts, and gas sensing applications due to quantum confinement effects and large surface area. Excellent application potential.

Generally, the porous tantalum nanowire is prepared by using a doped germanium substrate and performing one-stage etching using metal ions/hydrofluoric acid/hydrogen peroxide (eg, Huihui Chen et al., J. Mater. Chem ., 2011, 21 , 801-805), or the use of metal ions / hydrofluoric acid and hydrofluoric acid / nitric acid for two-stage etching (such as Xu Wenyi in his master's thesis "metal-triggered etching to prepare single crystal germanium wire and its field Revealed in the Study of Emission Characteristics). However, since the low-doped medium resistivity and high resistivity ruthenium substrate are not easily porous to form a porous structure, the above-described method generally requires the use of a highly doped low resistivity ( 10 Ω-cm) 矽 substrate can be used to make porous nanowires with high roughness, which is not only expensive but also limited in application, and can not independently regulate the pore size of the prepared nanowires. length.

It can be seen from the above statement that there are still many problems in the preparation of porous tantalum nanowires by using the existing etching method, such as being able to effectively overcome the limitation of the low resistivity substrate, and the porous rice nanowire can be prepared in a large area, and the pore diameter can be easily controlled. Size, for the industrial preparation of porous tannins will be quite helpful.

Accordingly, it is an object of the present invention to provide a method for producing a porous tantalum nanowire which can overcome the limitations of a substrate having a low electrical resistivity and can easily control the pore size of the porous tantalum nanowire.

Thus, the method for producing a porous tantalum nanowire of the present invention comprises: (a) reacting a tantalum substrate with an etching solution, and etching to form a plurality of tantalum nanowires, wherein the etching solution contains metal ions; and (b) The nanowire is immersed in an electrolyte and an electric current is applied, thereby obtaining a plurality of porous nanowires.

Accordingly, another object of the present invention is to provide a porous tantalum nanowire which is produced by a method for producing a porous tannin wire as described above.

The effect of the invention is that the method for preparing the porous tantalum nanowire of the invention can be made into a porous tantalum nanowire by a metal-induced etching and electrochemical treatment.

The method for preparing a porous tantalum nanowire of the present invention comprises: (a) reacting a tantalum substrate with an etching solution, and etching to form a plurality of tantalum nanowires, wherein the etching solution contains metal ions; and (b) the same The nanowire is immersed in an electrolyte and an electric current is applied, thereby obtaining a plurality of porous tantalum wires.

Preferably, the tantalum substrate has a resistivity ranging from 0.001 to 1200 Ω-cm. More preferably, the tantalum substrate has a resistivity ranging from 0.008 to 770 Ω-cm. Most preferably, the tantalum substrate has a resistivity ranging from 670 to 770 Ω-cm.

Preferably, the ruthenium substrate is a single crystal ruthenium substrate.

The metal ions may be deposited on the surface of the tantalum substrate and reduced to metal particles while oxidizing the tantalum substrate around it to ruthenium dioxide. The metal ion is selected from metal ions having a high reduction potential. Preferably, the metal ion is selected from the group consisting of silver ions, gold ions, platinum ions, copper ions or a combination thereof. In a particular embodiment of the invention, the metal ion is a silver ion. The source of the metal ion may be, for example, various metal salts such as silver nitrate or the like.

Preferably, the etching solution further comprises hydrofluoric acid and hydrogen peroxide. Hydrofluoric acid can etch cerium oxide; hydrogen peroxide helps the cerium substrate to oxidize to cerium oxide, which accelerates the etching reaction.

Preferably, the electrolyte comprises hydrofluoric acid and hydrogen peroxide. Hydrofluoric acid can etch cerium oxide; hydrogen peroxide helps the cerium substrate to oxidize to cerium oxide, which accelerates the etching reaction.

Preferably, the current is applied in the range of 0.001 to 0.008 A. If the current is too large, the pores of the porous nanowire are too large, and it is easy to break and it is difficult to form a neatly arranged array. If the current is too small, it is impossible to break through the required energy barrier to form a porous structure. More preferably, the current is applied in the range of 0.006 to 0.008 A.

Preferably, the current application time ranges from 1 to 5 min. If the application time is too long, the pores of the porous nanowire are too large and easily broken, and it is difficult to form a neatly arranged array. However, if the application time is too short, the porous structure cannot be smoothly produced.

The porous tantalum nanowire of the present invention is produced by a method for producing a porous tannin wire as described above, wherein the porous nanowire has a resistivity ranging from 11 to 1200 Ω-cm. Preferably, the porous nanowires have a resistivity ranging from 100 to 1200 Ω-cm. More preferably, the porous nanowires have a resistivity ranging from 670 to 770 Ω-cm.

The invention is further described in the following examples, but it should be understood that these examples are for illustrative purposes only and are not to be construed as limiting.

<Example 1>

The method for preparing the porous tannin wire of Example 1 comprises the following steps:

(a) A single crystal germanium substrate having a (100) plane and a resistivity of 0.008 to 0.02 Ω-cm is immersed in a 5 M hydrofluoric acid, 0.02 M silver nitrate aqueous solution and 0.22 M aqueous hydrogen peroxide solution. The reaction was carried out for 1 hour in the etching solution, and then the treated coffin was taken out, and the silver particles remaining on the coffin after the reaction were removed with 20 vol% nitric acid to obtain a coffin after the reaction.

(b) providing an electrochemical device comprising an electrolyte containing 4 M hydrofluoric acid and 3.25 M aqueous hydrogen peroxide solution, a working electrode and a reference electrode spaced apart from the electrolyte, a power supply and a connection Two electrodes and wires of the power supply. The reacted coffin was immersed in the electrolyte, and the reacted coffin was brought into contact with the working electrode, and a voltage of 45 V and a current of 0.007 A were applied to the coffin after the reaction for 1 min to obtain a crucible. Material product.

<Example 2>

The production method of Example 2 was the same as that of Example 1 except that the specific resistance of the single crystal germanium substrate of the step (a) was changed to 1 to 5 Ω-cm.

<Examples 3 to 4>

The production methods of Examples 3 to 4 were the same as in Example 2 except that the energization time of the step (b) was changed to 2 and 3 minutes.

<Example 5>

The production method of Example 5 was the same as that of Example 1 except that the specific resistance of the single crystal germanium substrate of the step (a) was changed to 660 to 770 Ω-cm.

<Examples 6 to 7>

The preparation of Examples 6 to 7 was the same as that of Example 5 except that the energization time of the step (b) was changed to 3 and 5 minutes.

<Comparative Example 1>

The preparation method of Comparative Example 1 was the same as that of the step (a) of Example 2, but the step (b) was not carried out.

<Comparative Example 2>

The preparation of Comparative Example 2 was the same as that of the step (a) of Example 2, except that the current application in the step (b) was changed to 0.005 A and the energization time was changed to 20 minutes.

The specific resistance, current application, and energization time of the single crystal germanium substrates in the above-described Examples 1 to 7 and Comparative Examples 1 and 2 were respectively summarized in Table 1 below.

<Electron Microscope Observation>

The surface morphology of the coffin products obtained in Examples 1 to 7 and Comparative Examples 1 and 2 was observed by a field emission scanning electron microscope (FE-SEM, available from Hitachi, model S4800). The results are shown in Figures 1-9. Shown. In Figures 1-7, it can be seen that the coffin products obtained in Examples 1 to 7 are all plural porous nanowires. Comparing the partial enlarged views embedded in FIG. 2 to FIG. 4, it can be found that the tantalum nanowire prepared in Example 4 has a plurality of holes larger than that of the third embodiment, and the tantalum nanowire prepared in the third embodiment has a plurality of comparative examples. 2 larger pores, so it can be inferred that the pore size (roughness) of the coffin product increases with the increase of the energization time of the step (b); the same conclusion can be obtained by comparing Figs. 5A, 6A and 7A. In FIG. 8, it can be found that the coffin product obtained in Comparative Example 1 is also an array of a plurality of tantalum nanowires; however, in the partially enlarged view embedded in FIG. 8, the surface of the tanned nanowires can be found to be smooth. There are no holes. In Fig. 9A, it was found that the coffin product obtained in Comparative Example 2 was not an array of plural nanowires (even in Fig. 9B, it was found that the coffin product obtained in Comparative Example 2 had a plurality of pores). From this, it can be confirmed that the process of the present invention can indeed produce a porous nanowire.

<fluorescence spectrum analysis>

Fluorescence spectrometer (purchased from HORIBA, model Labram HR, source of He-Cd laser source) was used to provide 325 nm incident light to the coffin products obtained in Example 4 and Comparative Example 1, respectively, and measured in visible light. The photoluminescence properties of the band are shown in Figure 10. It can be seen from Fig. 10 that the coffin product obtained in Example 4 has a distinct luminescence peak at 698 nm, and the coffin product obtained in Comparative Example 1 has no significant luminescence peak in the visible light band, showing that Example 4 is electrogenerated. The quantum confinement effect of the processed coffin product due to the nanometer-scale porous structure shifts the emission wavelength of the coffin from the infrared band to the visible band.

<contact angle analysis>

A small amount of the coffin products prepared in Example 4 and Comparative Example 1 were placed on a cover glass, and the coverslips were placed on the platform, and water droplets were dropped on the coffin products, respectively, and the water droplets and caps were measured. The contact angle of the slide, the results are shown in Figure 11. In Fig. 11A, it can be found that the contact angle of the coffin product obtained in Comparative Example 1 is 10°, which indicates that it is not hydrophobic; in Fig. 11B, the contact angle of the coffin product obtained in Example 4 can be found. At 164°, it is shown to be significantly hydrophobic and has the potential to be applied to self-cleaning materials.

Similarly, the tantalum products obtained in Examples 2 and 3 were subjected to the above contact angle analysis, and it was found that the contact angle of the coffin product obtained in Example 2 was 26°, and the contact angle of the coffin product obtained in Example 3 was 158°.

In summary, the method for preparing a porous tantalum nanowire of the present invention can form a porous germanium wire of different resistivity by a metal induced etching step (a) and an electrochemical treatment step (b); The pore size and surface hydrophobicity of the prepared porous nanowire can be easily controlled by changing the length of the current application time.

The above is only the preferred embodiment and the specific examples of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent change according to the scope of the invention and the description of the invention. And modifications are still within the scope of the invention patent.

Figure 1 is a SEM photograph showing the surface morphology of the coffin product obtained in Example 1 using a field emission scanning electron microscope;

Figure 2 is a SEM photograph showing the surface morphology of the coffin product obtained in Example 2 using a field emission scanning electron microscope;

Figure 3 is a SEM photograph showing the surface morphology of the coffin product obtained in Example 3, measured by a field emission scanning electron microscope;

Figure 4 is a SEM photograph showing the surface morphology of the coffin product obtained in Example 4, measured by a field emission scanning electron microscope;

Figure 5 is a SEM photograph showing the surface morphology of the coffin product obtained in Example 5 using a field emission scanning electron microscope;

Figure 6 is a SEM photograph showing the surface morphology of the coffin product obtained in Example 6 measured by a field emission scanning electron microscope;

Figure 7 is a SEM photograph showing the surface morphology of the coffin product obtained in Example 7 using a field emission scanning electron microscope;

Figure 8 is a SEM photograph showing the surface morphology of the coffin product obtained in Comparative Example 1 measured by a field emission scanning electron microscope;

Figure 9 is a SEM photograph showing the surface morphology of the coffin product obtained in Comparative Example 2, measured by a field emission scanning electron microscope;

Figure 10 is a photoluminescence spectrum showing the photoluminescence properties of the coffin products obtained in Example 4 and Comparative Example 1 in the visible light region by using a fluorescence spectrometer;

Figure 11 is a comparative diagram showing the results of contact angle analysis of the coffin products obtained in Comparative Example 1 (Figure 11A) and Example 4 (Figure 11B).

Claims (8)

A method for preparing a porous tantalum nanowire, comprising: (a) reacting a substrate with an etching solution, and etching to form a plurality of nanowires, wherein the etching solution contains metal ions; and (b) The nanowire is immersed in an electrolyte and an electric current is applied to form a plurality of holes on the surface of the nanowire; wherein the current is applied in a range of 0.006 to 0.008 A, and the current application time ranges from 1 to 5 min; The length of the nanowire after the current is applied is not greater than the length before the current is applied. The method for producing a porous tantalum nanowire according to claim 1, wherein the tantalum substrate has a resistivity ranging from 0.001 to 1200 Ω-cm. The method for producing a porous tannin wire according to the second aspect of the invention, wherein the base material has a resistivity ranging from 0.008 to 770 Ω-cm. The method for producing a porous tannin wire according to the third aspect of the invention, wherein the base material has a resistivity ranging from 670 to 770 Ω-cm. The method for producing a porous tannin wire according to the above aspect of the invention, wherein the base material is a single crystal germanium substrate. The method for producing a porous tannin wire according to claim 1, wherein the metal ion is selected from the group consisting of silver ions, gold ions, platinum ions, copper ions or a combination thereof. The method for producing a porous tannin wire according to the above aspect of the invention, wherein the electrolyte comprises hydrofluoric acid and hydrogen peroxide. A porous tannin wire produced by the method of porous nanowires as described in claim 1, wherein the porous nanowires have a resistivity ranging from 11 to 1200 Ω-cm. .