JP3867374B2 - Aqueous solution for preparing titanium oxide film and method for producing titanium oxide film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aqueous solution for producing a titanium oxide film that can be used for a photocatalyst, a photochemical battery, an ultraviolet absorbing film, a dielectric film, and the like, and a method for producing a titanium oxide film using the aqueous solution.
[0002]
[Prior art]
Conventionally, titanium oxide coatings have been used in fields such as photocatalysts, photochemical cells, ultraviolet absorbing films, and dielectric films.
[0003]
As a method for producing such a titanium oxide film, attempts have been made to form a film on a substrate by a dry film forming method such as a sputtering method, a vacuum evaporation method, or a CVD method. In the wet film-forming method, a titanium oxide film is obtained by anodizing titanium metal in an acid or alkali solution, or as described in Journal of Electrochemical Society 143, 1547 (1996), There is known a method for producing a titanium oxide film by cathodic deposition in an acidic solution having a pH of 1.0 to 3.0 containing titanium ions.
[0004]
[Problems to be solved by the invention]
However, the dry deposition methods such as the conventional sputtering method, vacuum deposition method, and CVD method are large and expensive, and the substrate area on which the film can be formed is limited. It is difficult to control the composition and film thickness. Complex substrates have drawbacks such as difficulty in film formation. Further, in the wet film formation method, the usable substrate is limited in the method of anodizing titanium metal, and the aluminum that is eluted in the acidic solution also in the method of cathodic deposition in an acidic solution containing titanium ions. In addition, it is difficult to form a titanium oxide film on a metal such as zinc, tin, or lead, or an oxide substrate. In addition, a precipitate is formed in the solution in a solution exceeding pH 3.0. There were problems such that it was impossible to use the film.
[0005]
[Means for Solving the Problems]
As a result of intensive studies in view of the above technical problems, the present inventor used an aqueous solution containing titanium ions, nitrate ions, peroxides, and complexing agents and having a pH of more than 3.0. By performing electrolytic deposition, a titanium oxide film can be easily produced on a large-area or complex-shaped substrate, with a uniform film thickness and composition and capable of selecting a wide range of substrates, without requiring a large-scale apparatus. A method that can be used has been found and the present invention has been completed.
[0006]
That is, the present invention includes an aqueous solution containing titanium ions, nitrate ions, peroxides, and a complexing agent and having a pH higher than 3.0, and electrolytic deposition of a titanium oxide film using the aqueous solution. It is characterized by.
[0007]
There is no limitation in particular as an ion source of the titanium ion in this invention. That is, any water-soluble titanium salt may be used, for example, titanium trichloride, titanium tetrachloride, and the like. Further, titanium metal, titanium oxide, etc. may be combined with sulfuric acid, nitric acid, hydrofluoric acid, and hydrogen peroxide water. What was dissolved in the aqueous solution which mixed ammonia water can be used.
[0008]
There is no particular limitation on the ion source of nitrate ions. That is, nitric acid, sodium nitrate, potassium nitrate, ammonium nitrate and the like can be mentioned.
[0009]
There is no particular limitation on the peroxide. Hydrogen peroxide, peroxonitric acid, peroxomonosulfuric acid, peroxodisulfuric acid, sodium peroxodisulfate, sodium peroxodisulfate, potassium peroxomonosulfate, potassium peroxodisulfate, sodium peroxomonocarbonate, potassium peroxodicarbonate, peroxomonophosphorus Acid, peroxodiphosphate, sodium peroxomonophosphate, sodium peroxodiphosphate, potassium peroxomonophosphate, potassium peroxodiphosphate, peroxoborate, sodium peroxoborate and the like.
[0010]
Furthermore, examples of the complexing agent include ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetate, citric acid, sodium citrate, nitrilotriacetic acid, sodium nitrilotriacetate, and cyclohexanediaminetetraacetic acid.
[0011]
Of these compounds, titanium tetrachloride as the titanium ion source, nitric acid as the nitrate ion source, peroxoboric acid as the peroxide, and citric acid as the complexing agent make each reagent easy to handle and easy to prepare. It is desirable to think from.
[0012]
In the present invention, a compound used as a titanium ion source and a nitrate ion source, a peroxide, and a compound used as a complexing agent may each be a single type or a mixture of a plurality of types. May be.
[0013]
In the present invention, the concentration of titanium ion, nitrate ion peroxide, and complexing agent can be used in a wide range. However, if the concentration is too low, it is difficult to obtain a coating film by electrolysis, and if the concentration is too high, the stability of the aqueous solution is decreased. It tends to worsen and produce a precipitate. For this reason, it is usually appropriate that the concentrations of titanium ions, nitrate ions, peroxides, and complexing agents are in the range of about 0.001 mol / L to 1.0 mol / L. It is preferably about 0.05 mol / L.
[0014]
For the method for producing a titanium oxide film of the present invention, any of ordinary electrolytic deposition methods such as an electrolytic plating method and a hydrothermal electrochemical method in which electrolysis is performed under high temperature and high pressure in an autoclave can be adopted.
[0015]
In the present invention, as described above, a titanium oxide film is formed using an aqueous solution containing titanium ions, nitrate ions, peroxides, and a complexing agent and having a pH higher than 3.0. In the case of using an aqueous solution containing titanium ions and nitrate ions but not containing peroxides and complexing agents, and an aqueous solution containing titanium ions, nitrate ions and peroxides but not containing complexing agents, As a result, a titanium oxide film cannot be produced.
[0016]
When the aqueous solution of the present invention is used, for example, when a tripolar electrolytic cell is used as a forming apparatus, the working electrode potential is set to the concentration of titanium ion, nitrate ion, peroxide, and complexing agent in the electrolytic solution. Although it can be set according to the standard, it is usually about −0.1 to −2.0 V, preferably about −0.5 to −1.5 V, preferably −0.8 to −1 based on the Ag / AgCl electrode standard. About 3V is particularly preferable. Moreover, although the liquid temperature of electrolyte solution can be set in the wide range, about 10 to 100 degreeC is suitable normally, and about 50 to 80 degreeC is preferable. If the pH of the aqueous solution is larger than 3.0, it is possible to form a titanium oxide film in a wide range. However, depending on the pH adjusted at this time, a precipitate may be formed during the adjustment of the electrolytic solution, or the electrolytic solution may be generated during electrolysis. Or the like, and a good titanium oxide film cannot be obtained. Therefore, it is appropriate to adjust the pH to about 3.0 to 9.0, and to about 5.0 to 8.0. It is preferable from the viewpoint of solubility.
[0017]
Various known substrates can be used as the substrate on which the titanium oxide film of the present invention is formed. For example, metal materials, such as aluminum, copper, nickel, platinum, gold | metal | money, stainless steel, ceramic material, glass material etc. are mentioned. In addition, the substrate may be subjected to treatment such as surface modification and electrical conductivity before electrolysis.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, experiments conducted according to the present invention will be described. The chemicals used were all reagent grade (manufactured by Nacalai Tesque). As a substrate for producing a titanium oxide film (that is, working electrode), titanium and platinum are stacked by 100 nm and 300 nm, respectively, on a silicon wafer with a thermal oxide film (manufactured by Osaka Special Metal Co., Ltd.) by vacuum deposition, and the outermost surface is platinum. In accordance with a conventional method, degreasing and etching treatment were performed using the material covered with. In addition, the electrolysis cell is a commonly used three-electrode type (counter electrode: Pt foil 20 × 30 × 0.1 mm, manufactured by High Purity Chemical Co., Ltd., reference electrode: Ag / AgCl with saturated KCl, HORIBA, Ltd. ), Cell capacity: 300 mL).
[0019]
[Example 1]
An aqueous solution for preparing a titanium oxide film having the following composition was placed in an electrolytic cell, and after setting in a thermostatic chamber, electrolysis was performed under the following conditions.
[0020]
Titanium tetrachloride 0.05 mol / L
Sodium nitrate 0.05 mol / L
Peroxoboric acid 0.05 mol / L
Citric acid 0.05 mol / L
(Adjusted to pH 6 with 28 wt% aqueous ammonia)
When electrolysis was performed in the above aqueous solution at a liquid temperature of 60 ° C. and −1.0 V for 20 minutes, a transparent film was formed on the substrate. When this film was measured by X-ray photoelectric spectroscopy, a Ti _2p peak was observed as shown in FIG. 1, and it was found that titanium oxide was produced from the Ti _2p3 peak.
[0021]
[Example 2]
An aqueous solution for preparing a titanium oxide film having the following composition was placed in an electrolytic cell, and after setting in a thermostatic chamber, electrolysis was performed under the following conditions.
[0022]
Titanium trichloride 0.05 mol / L
Nitric acid 0.05 mol / L
Sodium peroxodisulfate 0.05 mol / L
Ethylenediaminetetraacetic acid 0.05 mol / L
(Adjusted to pH 5 with 28 wt% aqueous ammonia)
When electrolysis was performed in the above aqueous solution at a liquid temperature of 50 ° C. and −1.0 V for 20 minutes, a translucent film was formed on the substrate. When this film was identified by X-ray photoelectric spectroscopy in the same manner as in Example 1, it was a titanium oxide.
[0023]
[Example 3]
An aqueous solution for preparing a titanium oxide film having the following composition was placed in an electrolytic cell, and after setting in a thermostatic chamber, electrolysis was performed under the following conditions.
[0024]
Titanium tetrachloride 0.01 mol / L
Ammonium nitrate 0.01 mol / L
Sodium peroxodicarbonate 0.01 mol / L
Sodium nitrilotriacetate 0.01 mol / L
(Adjusted to pH 5 with 28 wt% aqueous ammonia)
In the above aqueous solution, the liquid temperature was kept at 65 ° C., and electrolysis was performed at −0.9 V for 20 minutes. As a result, a translucent film was formed on the substrate. When this film was identified by X-ray photoelectric spectroscopy in the same manner as in Example 1, it was a titanium oxide.
[0025]
[Example 4]
Prior to preparing an aqueous solution for preparing a titanium oxide film, 4.79 g of 350 mesh Ti powder was put into a mixed solution consisting of 50 ml of 30 wt% hydrogen peroxide water and 50 ml of 28 wt% ammonia water, dissolved, and gel A product was obtained. The powder obtained by drying this gel was dissolved in a 1 mol / L nitric acid aqueous solution and taken out into the electrolytic cell so that the following titanium ion and nitrate ion concentrations were obtained. Next, an aqueous solution for preparing a titanium oxide film was prepared as follows.
[0026]
Titanium ion 0.03 mol / L
Nitrate ion 0.03 mol / L
Hydrogen peroxide 0.01mol / L
Sodium citrate 0.02 mol / L
(Adjusted to pH 7 with 28 wt% aqueous ammonia)
When electrolysis was performed in the above aqueous solution at a liquid temperature of 50 ° C. and −1.2 V for 30 minutes, a translucent film was formed on the substrate. When this film was identified by X-ray photoelectric spectroscopy in the same manner as in Example 1, it was a titanium oxide.
[0027]
[Comparative Example 1]
After putting an electrolytic solution for producing a zinc oxide film having the following composition into an electrolytic cell, the electrolytic cell was set in a thermostatic chamber, and then electrolyzed under the following conditions.
[0028]
Titanium trichloride 0.05mol / L
Sodium nitrate 0.05mol / L
Sodium peroxoborate 0.05mol / L
When an attempt was made to gradually raise the pH of the above aqueous solution using a 28 wt% aqueous ammonia solution, a precipitate was formed around pH 2.8, and it was difficult to adjust the pH. For this reason, electrolytic deposition was impossible.
[0029]
【The invention's effect】
Thus, according to the present invention, a large-scale apparatus is obtained by performing electrolytic deposition using an aqueous solution containing titanium ions, nitrate ions, peroxides, and complexing agents and having a pH of greater than 3.0. A titanium oxide film having a uniform film thickness and composition and capable of selecting a wide range of substrates can be easily manufactured on a substrate having a large area and a complicated shape.
[Brief description of the drawings]
FIG. 1 is a diagram showing an X-ray photoelectric spectroscopic chart in Example 1 of the present invention.

Claims (4)

An aqueous solution for producing a titanium oxide film characterized by containing titanium ions, nitrate ions, peroxides, and a complexing agent, and having a pH of greater than 3.0 ,
Titanium oxidation characterized by using at least one of ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid, citric acid, citrate, nitrilotriacetic acid, nitrilotriacetic acid, and cyclohexanediaminetetraacetic acid as the complexing agent. Aqueous solution for physical coating .    The titanium oxide film according to claim 1, wherein the peroxide is at least one of hydrogen peroxide, peroxo acid, peroxo carbonate, peroxophosphate, and peroxoborate. Aqueous solution. Titanium ions, nitrate ions, peroxides, and contains a complexing agent, and a pH in 3.0 greater aqueous solution, a method of manufacturing facilities to titanium oxide coating electrolytic deposition,
Titanium oxidation characterized by using at least one of ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid, citric acid, citrate, nitrilotriacetic acid, nitrilotriacetic acid, and cyclohexanediaminetetraacetic acid as the complexing agent. Manufacturing method of physical coating . The titanium oxide film according to claim 3 , wherein at least one of hydrogen peroxide, peroxo acid, peroxo carbonate, peroxophosphate, and peroxoborate is used as the peroxide. Production method.

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