JP2003024785A - Zinc oxide film having photocatalytic property and method for forming the film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a zinc oxide film having photocatalytic properties. SOLUTION: In a method for forming the zinc oxide film having photocatalytic properties, a zinc oxide film manufactured by a wet plating method is treated in an aqueous solution containing at least one kind of metal ions the metal of which is selected from Ag, Pd, Au, Pt, Fe, Mn, and Co.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photocatalytic zinc oxide film and a method for forming the same.

[0002]

2. Description of the Related Art Since titanium oxide has excellent photocatalytic properties, it has been applied to various fields. Further, since zinc oxide also has a band gap of 3.3 eV, it is expected to have a photocatalytic property equivalent to that of titanium oxide.

However, the zinc oxide film has many problems in maintaining the photocatalytic property due to its deterioration and the like. An object of the present invention is to solve these problems and provide a zinc oxide film having excellent photocatalytic properties for a long time and a method for forming the same.

[0004]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above object, the present inventor has found that the wet plating method (electroless plating method or electrolytic plating method) is used.
The zinc oxide film produced by Ag, Pd, Au, P
It has been found that it has excellent photocatalytic properties by treating with an aqueous solution containing at least one metal ion selected from t, Fe, Mn, and Co, and more preferably by subjecting it to a reduction treatment.

That is, conventionally, zinc oxide having an average primary particle size of 0.1 to 0.5 μm is suspended in an aqueous solution containing a noble metal ion and the surface of the zinc oxide is adsorbed and impregnated with the noble metal ion.
Then, there is known a method for producing a noble metal-supported photocatalyst, which comprises supporting the noble metal ultrafine particles on the surface of the zinc oxide by reducing in a reducing aqueous solution (JP-A-11-179).
No. 205). This method uses fine particles as zinc oxide, and it is said that the fine particles of zinc oxide are produced by a dry method and not fine particles produced by a wet method. Also, as precious metals,
Particularly, Pd or Pt is said to be preferable.

However, as a result of various studies by the present inventors, a zinc oxide plating film as a continuous film by the wet plating method was found to be Ag, Pd, Au, Pt, Fe, Mn or Co.
It was discovered that, when immersed in an aqueous solution containing ions, a surprisingly excellent photocatalytic effect can be obtained, and the present invention has been completed.

Accordingly, the present invention provides the following method for forming a zinc oxide film having photocatalytic properties and a modified zinc oxide film obtained by the method. Claim 1: A photocatalytic property, characterized in that a zinc oxide film produced by a wet plating method is treated with an aqueous solution containing at least one metal ion selected from Ag, Pd, Au, Pt, Fe, Mn, and Co. A method for forming a zinc oxide film having the same. (2) A method for forming a zinc oxide film having photocatalytic properties, which comprises further reducing the film produced by the method according to (1). Claim 3: Obtained by the method according to claim 1 or 2, wherein the surface is modified with at least one metal selected from Ag, Pd, Au, Pt, Fe, Mn and Co, or a compound containing the metal. A zinc oxide film having a photocatalytic property, which is characterized by Claim 4: The ratio of the metal or metal compound to zinc oxide is 0.01 to 30% by weight as a metal.
A zinc oxide film having the described photocatalytic property.

The present invention will be described in more detail below.
The photocatalytic zinc oxide film of the present invention is obtained by modifying the surface of the zinc oxide film formed on the substrate by the method described below. This zinc oxide film is formed on the substrate. It is formed by a wet plating method (electroless plating method or electrolytic plating method).

Here, although the base material is not particularly limited, NESA glass, ITO glass, a metal plate or the like can be used as the conductive base material, and the non-conductive base material is a glass substrate, plastic, ceramic, Examples thereof include glass fiber, glass cloth, non-woven fabric, and natural fiber.

When an electroless zinc oxide film is formed on such a substrate, the following steps can be performed. (1) Washing: A known degreasing agent or organic solvent can be used, and processing can be performed under known processing conditions. (2) Surface conditioning: A known surface conditioning agent is used to impart an electric charge to the substrate surface. (3) Catalyst application: A known catalyst application agent is used to apply a catalyst to the substrate surface. (4) Preparation of electroless zinc oxide film: A zinc oxide film is deposited on the substrate.

In this case, as the surface conditioner, an aqueous solution containing 1 to 50 g / L of a cationic surfactant or a cationic polymer compound as a main component can be used. It can be immersed for 10 minutes.

In the catalyst application treatment in the step (3), any of the catalyst treatment steps for forming an electroless plating film such as a sensitizing-activating method, a catalyst-accelerator method, an alkaline catalyst method and the like. Can be used.

Further, the electroless zinc oxide film depositing solution in the step (4) is not particularly limited as long as it is a liquid for depositing zinc oxide, but a zinc salt such as zinc nitrate is 0.01 to 0. 0.5 mol / L, preferably 0.05-
0.001 to 0.5 mol of 0.2 mol / L and borane-based reducing agents such as dimethylamine borane and other reducing agents
/ L, preferably 0.01 to 0.2 mol / L, particularly 0.05 to 0.15 mol / L, and a treatment liquid having a pH of about 4 to 9 and particularly about 6.5 can be suitably used. A method of immersion treatment at 80 ° C. for 10 to 200 minutes can be adopted.

On the other hand, when forming an electrolytic zinc oxide film, it can be carried out in the following steps. (1) Washing: A known degreasing agent or organic solvent can be used, and processing can be performed under known processing conditions. (2) Preparation of electrolytic zinc oxide film: A zinc oxide film is deposited on the substrate.

In this case, the electrolytic zinc oxide film depositing solution in the step (2) is not particularly limited as long as it is a liquid that deposits zinc oxide, but zinc salts such as zinc nitrate 0.01 to 0. 5 mol / L, preferably 0.05 to
PH of about 4-9 containing 0.2 mol / L, especially pH
The treatment liquid of 6.0 can be preferably used, and zinc, carbon, platinum or the like is used as the anode, and a zinc oxide film is formed by applying 0.1 to 20 coulombs, preferably 1 to 10 coulombs per cm ^{2 of the} conductive substrate. Can be obtained. Bath temperature is 1
It is used in the range of 0 to 80 ° C.

The zinc oxide film has a thickness of 0.001 to
The thickness can be 2 μm, particularly 0.01 to 1 μm,
It is not limited to this.

The present invention is a photocatalytic zinc oxide film produced by modifying the surface of the zinc oxide film obtained as described above.

In this case, the zinc oxide film modifier according to the present invention contains one or more of Ag, Pd, Au, Pt, Fe, Mn and Co ions. The counter anion is not particularly limited as long as it makes the metal compound water-soluble, but is not particularly limited.
Examples thereof include sulfate ion, halogen ion, phosphate ion, nitrate ion, acetate ion, citrate ion, lactate ion, and other carboxylate ion. It is effective that the above metal ion is contained in an aqueous solution in an amount of 0.01 to 50 g / L, and more preferably 0.1 to 30 g / L.

P of the above-mentioned metal ion-containing aqueous solution (modifying agent)
It is preferable that H is 2 to 10, particularly 3 to 8. The conditions for treating the zinc oxide film with the modifier of the present invention are appropriately selected, but are 10 to 60 ° C., particularly 20 to 40 ° C.
Conditions for treating for 1 second to 10 minutes, especially about 5 seconds to 5 minutes can be adopted, and the treatment can be performed by immersing the zinc oxide film in the modifier, but spray treatment or the like is also possible. . In this case, in the modified zinc oxide film, the metal of the modifier or the compound containing the metal is 0.01 to 30% by weight, preferably 0.1 to 10% by weight, and more preferably 0.1 to 10% by weight as a metal. It is preferable that the content is up to 5% by weight. If it is out of this range, the photocatalytic property may decrease. Further, in order to maintain transparency, the content is realized by 30% by weight or less, and when imparting conductivity, it is realized by 0.01% by weight or more.

Further, according to the present invention, the modified zinc oxide film obtained as described above can be subjected to a reduction treatment. This reduction treatment is to reduce the metal ions attached to the surface of the modified zinc oxide film treated with the above-mentioned modifier to a metal, and in this case, any reduction step can be used for the reduction treatment, The process using a reducing agent is particularly effective. This reducing agent may be any reducing agent, especially KBH
Borane-based reducing agents such as ₄ , NaBH ₄ and DMAB (dimethylamine borane) are effective. The reducing solution contains a reducing agent of 0.
001 to 0.5 mol / L, preferably 0.005
0.2 mol / L, particularly preferably 0.01 to 0.1 m
A treatment liquid containing ol / L and having a pH of about 10 to 14 can be preferably used, and a method of immersion treatment at 10 to 80 ° C. for 10 seconds to 5 minutes is used.

According to the present invention, a zinc oxide film having excellent photocatalytic properties can be obtained by the above steps. In this case, it is not clear why the zinc oxide film having excellent photocatalytic properties was obtained, but due to the interaction between the zinc oxide film and the metal or the compound containing the metal used for the above modification,
It is considered that the photocatalytic property is improved.

The photocatalytic zinc oxide film of the present invention has a surface covered with the above-mentioned metal or metal compound (mainly an oxide of the metal, an alloy of the metal and zinc, particularly a metal oxide). When the elemental analysis of the surface of the modified zinc oxide obtained by the above method was carried out by ESCA (X-ray photoelectric spectroscopy), the outermost layer of the zinc oxide film was Ag, Pd, Au, P.
It was possible to confirm that it was covered with a metal of t, Fe, Mn, or Co or a compound thereof. The photocatalytic activity of the obtained zinc oxide film was evaluated for its activity against decomposition of acetaldehyde gas during Xe lamp irradiation, and it was confirmed that acetaldehyde gas with an initial concentration of 50 ppm decomposed to 1 ppm or less after 5 minutes. .

Therefore, since the zinc oxide film of the present invention is excellent in photocatalytic property, it is used for large substrates such as window glass used in vehicles, buildings, buildings, airplanes, fluorescent lamps, fluorescent lamp peripheral portions, and curtains. It can also be used for glass fibers, glass cloth, non-woven fabrics, natural fibers, etc. used for clothes and the like.

[0024]

According to the present invention, a zinc oxide film having a photocatalytic property can be formed.

[0025]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 4] Soda lime glass was used as a non-conductive substrate, washed with a commercially available degreasing agent, immersed in the following surface conditioner at 50 ° C for 5 minutes, and then washed with water, and then washed. Sensitize with the following sensitizing solution at 20 ° C. for 1 minute, and then with the following palladium activating solution, 20
Activation treatment was carried out at ℃ for 1 minute. Next, it was immersed in an electroless zinc oxide depositing solution shown below at 65 ° C. for 1 hour to deposit zinc oxide on the substrate by an electroless method. After that, a modified zinc oxide film (Example 1: Ag) was immersed in a modifier for zinc oxide shown below at 30 ° C. for 10 seconds, 1 minute, or 5 minutes, and then immersed in a reducing agent shown below. Modification, Example 2: modification with Fe, Example 3: modification with Pt,
Example 4: Modification with Pd) was obtained.

[0027] The degreasing agent Uemura & Asahi Cleaner Co., Ltd. C-4000 5g / L surface modifier Uemura & Co., Ltd. THRU-CUP CD-202 50mL / L sensitizing solution Uemura & Senses Co., Ltd. Advertiser S-10X 100mL / L palladium activating solution Uemura & Co. activator A-10X 100mL / L electroless zinc oxide plating solution _{Zn (NO 3) 2 · 6H} 2 O 30g / L dimethylamine borane 1 g / L pH 6.5 for zinc oxide film Modifier Example 1: Ag Modifier Silver Sulfate 1 g / L Ammonium Sulfate 0.5 g / L Example 2: Fe Modifier Iron Sulfate Heptahydrate 1 g / L Ammonium Sulfate 0.5 g / L Example 3: Pt Modifier Platinum chloride hexahydrate 1 g / L HCl 5 mL / L Example 4: Pd modifier Palladium chloride 0.2 g / L Hydrochloric acid 0 .2 mL / L reducing agent dimethylamine borane 6 g / L NaOH 1 g / L

Regarding the obtained modified zinc oxide film, ES
As a result of analyzing surface elements by CA, it was confirmed that the surface of the zinc oxide film was covered with Ag, Fe, Pt, and Pd. Further, the ratio of the modified metal is I after the film is dissolved.
It was calculated by measurement with a CP (inductively coupled plasma emission spectrophotometer).

[Comparative Example 1] A zinc oxide film which was not subjected to a modification treatment was prepared for the examples. Regarding the photocatalytic activity of the modified zinc oxide coatings obtained in Examples 1 to 4 and the zinc oxide coating of Comparative Example 1, the activity against the decomposition of acetaldehyde gas during Xe lamp irradiation was evaluated.

A cell made of quartz glass was used for the test, the acetaldehyde gas was adjusted to an initial concentration of 50 ppm, and the acetaldehyde gas concentration in the cell after irradiating the Xe lamp for 15 minutes was quantified by gas chromatography. analyzed. Table 1 shows the decomposition rate of acetaldehyde gas with respect to the initial concentration.

[0031]

[Table 1]

From the above results, it is recognized that the zinc oxide of the present invention is a film having excellent photocatalytic properties.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C23C 18/16 C23C 18/16 Z 28/00 28/00 B C25D 9/08 C25D 9/08 (72) Inventor Masaya Senkin 2-3-4 Fukaekita, Higashi-nari-ku, Osaka-shi, Osaka Prefecture Famiru Fukaebashi 307 (72) Inventor I-saki ▼ Masanobu Nara Prefecture North ▲ Katsura-Kumigaoka 1-chome Kawami-cho 1-4-chome 1 (72) Inventor Yoshiji Saijo 1-5-1, Exit Hirakata-shi, Osaka Prefecture F-term in Central Research Laboratory, Uemura Industrial Co., Ltd. (reference) 4G069 AA03 AA08 BA14B BA48A BB02A BB02B BB04A BB04B BC32A BC32B BC33A BC35A BC35B BC62A BC66A BC66A BC72A BC72B BC75A BC75B FA01 FA03 FB14 FB21 FB45 FC08 4K022 AA02 AA03 AA04 AA13 BA15 BA25 BA33 CA03 CA06 CA29 DA01 DB03 DB25 DB26 DB28 EA04 4K044 AA01 AA12 AA13 AA16 BA04 BA06 BA08 BA12 BB01 BB03 CA15 CA17 CA53

Claims (4)

[Claims] 1. A photocatalytic property characterized in that a zinc oxide film produced by a wet plating method is treated with an aqueous solution containing at least one metal ion selected from Ag, Pd, Au, Pt, Fe, Mn and Co. A method for forming a zinc oxide film having: 2. A method for forming a zinc oxide film having photocatalytic properties, which comprises further reducing the film produced by the method according to claim 1. 3. The method according to claim 1 or 2, wherein the surface is Ag, Pd, Au, Pt, Fe, Mn, Co.
A zinc oxide film having a photocatalytic property, which is modified with at least one metal selected from the group consisting of or a compound containing the metal. 4. The zinc oxide film having photocatalytic properties according to claim 3, wherein the ratio of the metal or the metal compound to zinc oxide is 0.01 to 30% by weight as a metal.