KR101728688B1 - Preparation method of photoelectrode base on tantalum nitride - Google Patents

Abstract

The present invention relates to a method for producing a tantalum nitride-based photoelectrode. More specifically, the present invention relates to a technology to produce tantalum nitride (Ta_3N_5) ensuring optimized photoelectrode performance by aging a coating solution which contains a tantalum precursor, and also to apply the same to a tantalum nitride-based photoelectrode.

Description

[0001] The present invention relates to a photoelectrode based on tantalum nitride,

The present invention relates to a method of manufacturing a tantalum nitride-based photoelectrode, and more particularly, to a method of manufacturing a tantalum nitride-based photoelectrode using a tantalum nitride (Ta ₃ N ₅ ) film having optimized photocatalytic performance through an aging treatment of a coating solution containing a tantalum precursor And a technique for applying the same to a tantalum nitride-based optical electrode.

Photocatalysis refers to a substance that catalyzes a chemical reaction by a variety of light sources, including sunlight. Photosynthesis occurring in the chlorophyll of a plant is a representative photocatalysis system. A photocatalytic system is water splitting to produce oxygen and hydrogen by decomposition of water (water splitting), CO ₂ reduction method (CO ₂ reduction) by using a CO ₂ production of various carbon compounds such as CO, formic acid, harmful organic substances to the human body And photodegradation which decomposes the polymer.

This photocatalytic system is a system that exerts its own action by using only sunlight without obtaining energy from the outside. Since the photocatalyst used here is harmless to the human body and can be reused under specific conditions, it can be considered as a next generation clean energy source. In particular, water decomposition produces hydrogen gas by decomposing water by the following equation.

H ₂ O → 1 / 2O ₂ + H ₂ (ΔG = 237 KJ / mol)

Water decomposition requires a photocatalyst that absorbs sunlight, causing electrons to exude from the valence band to the conduction band. The photocatalyst should be hydrophilic because it is inexpensive, harmless to the human body, excellent in stability, and often reacts directly with water.

A photocatalyst which exhibits excellent water-splitting activity under ultraviolet light is _{K 4 Nb 6 O 17, BaTiO} 4, NaTaO 3, La 2 Ti 2 O 7 and the like, in particular La ₂ Ti ₂ O ₇ having a layered perovskite structure, And exhibits excellent activity due to its unique electronic structure (Non-Patent Document 1). Nevertheless, in order to apply the water decomposition technique using the photocatalyst from a practical viewpoint, development of photocatalysts and photoelectrodes having better activity for absorbing light in the visible light region is required. Particularly, when the photocatalyst material is developed in the form of an electrode, oxidation and reduction reactions occur separately, and it is easy to separate hydrogen and oxygen gas generated in water decomposition. In addition, it is possible to fuse with electric energy generated from renewable energy such as solar cells, and is effective for achieving high light conversion efficiency.

Although metal nitride is attracting much attention as a photoelectrode material having visible light activity, development of a variety of synthesis methods compared with metal oxides is limited, and the performance is lowered even when it is synthesized. Therefore, it is required to develop a nitride synthesis method with improved performance. In the case of tantalum nitride, a photoelectrode manufacturing method based on anodizing method has been developed, but there is a problem of safety such as using hydrofluoric acid as an electrolytic solution in the manufacturing process, and development of a new method of manufacturing a photoelectrode is required.

Therefore, the present inventors have found that if tantalum nitride (Ta ₃ N ₅ ) can be produced by the aging treatment of a coating solution containing a tantalum precursor, and the performance of the photocatalyst electrode is optimized, The present invention can be applied to a tantalum-based optical electrode.

Non-Patent Document 1. Hwang, Dong Won, et al. J. Catal. 193.1 (2000): 40-48.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a tantalum nitride (Ta ₃ N ₅ ) thin film having optimized photocatalytic electrode performance through an aging treatment of a coating solution containing a tantalum precursor The present invention also provides a method for manufacturing a tantalum nitride-based optical electrode.

According to an aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: (a) aging a mixed solution of a tantalum precursor solution, an organic binder, and an organic solvent; (b) coating the aging-treated mixed solution on a substrate to form a thin film; (c) oxidizing the thin film; And (d) nitrating the oxidized thin film to form a photoelectrode coated with a tantalum nitride thin film on the substrate.

According to an embodiment of the present invention, the aging may be performed at 40-70 DEG C for 10 to 300 minutes.

According to another embodiment of the present invention, the aging may be performed for 40 to 80 minutes.

According to another embodiment of the present invention, at least one precursor selected from the group consisting of a chromium precursor, a manganese precursor, a cobalt precursor, a nickel precursor, a rhodium precursor, and a molybdenum precursor is added to the tantalum precursor solution before the step (a) Lt; RTI ID = 0.0 > 1-10 < / RTI >

According to another embodiment of the present invention, the step (c) may be carried out at 300-500 ° C.

According to another embodiment of the present invention, the step (d) may be performed at 700-1000 ° C.

According to another embodiment of the present invention, the form of the tantalum precursor may be at least one form selected from a chloride, a bromide, an iodide, a nitrate, a nitrite, a sulfate, an acetate, a sulfite, an acetylacetonate salt and a hydroxide have.

According to another embodiment of the present invention, the organic binder may be at least one selected from ethyl cellulose, methyl cellulose, carboxy cellulose, nitrocellulose, methacrylic acid ester, acrylic acid ester, polyvinyl alcohol and polyvinyl butyral .

According to another embodiment of the present invention, the organic solvent is selected from the group consisting of alpha-terpineol, water, acetone, N-methyl-2-pyrrolidone, N, N'-dimethylformamide, (N, N'-dimethylacetamide, isopropyl alcohol, methanol, ethanol, butanol, 2-ethoxyethanol, 2-butoxyethanol, 2-methoxypropanol, tetrahydrofuran It may be at least one selected from ethylene glycol, pyridine, N-vinylpyrrolidone, methyl ethyl ketone (butanone), formic acid, ethyl acetate and acrylonitrile.

According to another embodiment of the present invention, the material of the substrate may be one material selected from tantalum, quartz, alumina, and titanium.

According to another embodiment of the present invention, the thickness of the tantalum nitride thin film may be 200-400 nm.

According to another embodiment of the present invention, the size of the tantalum nitride particles may be 1-50 nm.

According to the present invention, there is provided a method of manufacturing a tantalum nitride-based photoelectrode comprising tantalum nitride (Ta ₃ N ₅ ) with optimized photocatalytic electrode performance through an aging treatment of a coating solution comprising a tantalum precursor .

1 is a schematic view showing a process of manufacturing a Ta ₃ N ₅ -based photoelectrode according to Example 1 of the present invention.
2 is a graph showing X-ray diffraction (XRD) characteristics of a Ta ₃ N ₅ -based photoelectrode prepared according to Example 1 of the present invention.
3 is a scanning electron microscope (SEM) image of a Ta ₃ N ₅ -based photoelectrode prepared according to Example 1 of the present invention.
4 is a schematic view illustrating a process of measuring photoelectrochemical characteristics of a Ta ₃ N ₅ -based photoelectrode fabricated according to Example 1 of the present invention.
5 is a graph showing the photoelectrochemical decomposition characteristics of the Ta ₃ N ₅ -based photoelectrode prepared in Examples 1 to 4 and Comparative Example 1 of the present invention.
6 is a graph showing photoelectrochemical decomposition characteristics of Ta ₃ N ₅ -based photoelectrodes prepared from Examples 1 to 4 and Comparative Example 1 of the present invention in the presence of a sacrificial reagent on an electrolyte.

In the following, various aspects and various embodiments of the present invention will be described in more detail.

According to an aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: (a) aging a mixed solution obtained by mixing a tantalum precursor solution, an organic binder, and an organic solvent; (b) coating the aging-treated mixed solution on a substrate to form a thin film; (c) oxidizing the thin film; And (d) nitrating the oxidized thin film to form a photoelectrode coated with a tantalum nitride thin film on the substrate.

The method of manufacturing a tantalum nitride-based optical electrode according to the present invention can produce a photocatalyst having excellent photoelectrochemical performance through aging treatment of a coating solution containing a tantalum precursor coated on a substrate.

According to an embodiment of the present invention, the aging may be performed at 40-70 DEG C for 10 to 300 minutes. In particular, in the case of the tantalum nitride-based photoelectrode fabricated by performing the aging in the temperature and time range, the tantalum nitride thin film was uniformly coated on the substrate without being peeled off, while the aging was performed outside the temperature and time range mentioned above It was confirmed that the photoelectrochemical catalytic performance of the synthesized thin film was inferior.

According to another embodiment of the present invention, the aging may be performed in the temperature range for 40 to 80 minutes. In the case of the tantalum nitride-based photoelectrode fabricated at the above temperature and time range, the X-ray diffraction analysis showed that no pattern other than Ta ₃ N ₅ was observed and the crystal structure of Ta ₃ N ₅ was uniquely synthesized Respectively. If the temperature and time range are out of the range, Ta ₃ N ₅ It was confirmed that the photocatalyst had a loss of photocatalytic performance due to the inclusion of a substance having a crystal structure other than the photocatalyst. In addition, the photocurrent density values of the catalysts aged for 10-300 minutes on a reversible hydrogen electrode (RHE) 1.23 V are similar, but when a smaller voltage is applied, the 40- It was confirmed that the performance of the catalyst aged for 80 minutes was remarkably excellent.

According to another embodiment of the present invention, at least one precursor selected from the group consisting of a chromium precursor, a manganese precursor, a cobalt precursor, a nickel precursor, a rhodium precursor, and a molybdenum precursor is added to the tantalum precursor solution before the step (a) -10 atomic percent, based on the total weight of the composition. The transition metal precursor is further added to the tantalum precursor solution and doped in the tantalum nitride structure to improve the photocatalytic effect.

According to another embodiment of the present invention, the step (c) may be performed at 300-500 ° C, and the step (d) may be performed at 700-1000 ° C.

As a specific example, the mixed solution aged in the step (a) is coated on a substrate using a rotary evaporator, and then dried in air at 300-500 ° C, preferably 350-450 ° C for 30-180 minutes, Is annealed for 50-70 minutes to oxidize to tantalum metal, cooled at room temperature and then heated at 700-1000 ° C, preferably 850-950 ° C for 30-180 minutes in an electric furnace under an ammonia atmosphere, May convert the oxidized tantalum metal to tantalum nitride by nitrogenating for 110-130 minutes to form a photoelectrode coated with a tantalum nitride thin film on the substrate.

The tantalum precursor may be in the form of chloride, bromide, iodide, nitrate, nitrite, sulfate, acetate, sulfite, , Acetylacetonate salt, and hydroxide, but the present invention is not limited thereto. Specifically, a chloride can be used.

The organic binder may be at least one selected from the group consisting of ethyl cellulose, methyl cellulose, carboxy cellulose, nitrocellulose, methacrylic acid ester, acrylic acid ester, polyvinyl alcohol and polyvinyl butyral. Preferably, ethylcellulose can be used.

The organic solvent may be selected from the group consisting of alpha-terpineol, water, acetone, N-methyl-2-pyrrolidone, N, N'-dimethylformamide, N, N'-diethylformamide, dimethylsulfoxide, (2-ethoxyethanol, 2-ethoxyethanol, 2-methoxypropanol, tetrahydrofuran (THF), ethylene glycol, pyridine, N-vinylpyrrolidone Any water solvent or polar organic solvent such as at least one selected from the group consisting of water, methyl ethyl ketone (butanone), formic acid, ethyl acetate, and acrylonitrile may be used. Alpha-terpineol may preferably be used.

Also, the material of the substrate may be one material selected from tantalum, quartz, alumina, and titanium, but is not limited thereto. Preferably, a tantalum metal substrate can be used.

According to another embodiment of the present invention, the thickness of the tantalum nitride thin film may be 200-400 nm, preferably 250-350 nm, and the size of the tantalum nitride particles is 1-50 nm, preferably 25- 35 nm.

Hereinafter, production examples and embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

Examples 1 to 4: ₃ N ₅  Based photo-electrode fabrication

1.0029 g of tantalum chloride was dissolved in 2.5 mL of ethanol to prepare a precursor solution. Then, a solution prepared by dissolving 0.25 g of ethyl cellulose and 2.5 mL of alpha-terpineol in 5.0 mL of ethanol in another container was mixed with the precursor solution to prepare a coating solution Respectively. Thereafter, the coating solution was aged in an oil bath at 50 캜 for a certain period of time, and then cooled to room temperature to obtain an aging solution.

The aging solution was coated on a tantalum metal substrate at a speed of 2000 rpm for 30 seconds using a rotary evaporator, and then heat-treated at 350 ° C for 10 minutes on a hot plate. The coating and the heat treatment were repeated three times. After the last heat treatment, annealing was performed in an electric furnace at 400 ° C for 1 hour in the air to oxidize the tantalum metal.

Then, after cooling to room temperature, a Ta ₃ N ₅ -based photoelectrode was prepared by nitriding at 900 ° C. for 2 hours in an electric furnace in which ammonia gas flows at 100 sccm, thereby converting into nitride. At this time, the temperature of the electric furnace was raised to 5 ° C / min. After the reaction, the furnace was gradually cooled to room temperature (see FIG. 1).

The aging time was 1, 2, 3, and 4 hours, respectively, and was set to 1 to 4 in the examples.

Comparative Example 1

A Ta ₃ N ₅ -based photoelectrode was prepared in the same manner as in Example 1 except that the coating solution was directly coated on a tantalum metal substrate without being subjected to an aging treatment.

Comparative Example 2

The same procedure as in Example 1 was carried out except that the polycrystalline tantalum (Ta) foil was annealed and nitrided without using the coating solution to prepare a photoelectrode.

2 is a graph showing X-ray diffraction (XRD) characteristics of a Ta ₃ N ₅ -based photoelectrode prepared according to Example 1 of the present invention.

Referring to FIG. 2, in the case of the Ta ₃ N ₅ -based photoelectrode fabricated in Example 1, a pattern of a material other than Ta ₃ N ₅ was not observed, indicating that the crystal structure of Ta ₃ N ₅ was uniquely synthesized And it can be confirmed that the Ta ₃ N ₅ crystal structure is uniquely synthesized in the case of the tantalum nitride-based photoelectrode manufactured by aging treatment for 40-80 minutes.

3 is a scanning electron microscope (SEM) image of a Ta ₃ N ₅ -based photoelectrode prepared according to Example 1 of the present invention.

Referring to FIG. 3, it can be seen that the Ta ₃ N ₅ thin film was uniformly coated on the tantalum metal substrate without being peeled off. The synthesized Ta ₃ N ₅ had a nano-sized particle shape of about 20 nm, It can be confirmed that a thin film having a thickness of about 300 nm is formed.

5 is a graph showing photoelectrochemical water decomposition characteristics of Ta ₃ N ₅ -based photoelectrodes prepared in Examples 1 to 4 and Comparative Example 1 of the present invention, FIG. 3 is a graph showing photoelectrochemical decomposition characteristics of a Ta ₃ N ₅ -based photoelectrode prepared from Comparative Example 1 in the presence of a sacrificial reagent on an electrolyte. FIG.

In order to measure photoelectrochemical properties, the catalytic properties of the oxidation reaction were investigated by irradiating the simulated sunlight. A 1M potassium hydroxide aqueous solution was prepared. A Ta ₃ N ₅ electrode was used as a working electrode, a Pt substrate was used as a counter electrode, and an Ag / AgCl (in 3M KCl) electrode was used as a reference electrode. All photoelectrochemical analyzes were carried out in a one-piece photoelectrochemical cell made of quartz to measure light with a certain threshold voltage.

Solar light was simulated using a solar simulator, and the solar light intensity was corrected to 1 Sun = 100 mW / cm ² using a silicon photodiode (see FIG. 4) before measurement. In order to measure the photocurrent and dark current according to the presence or absence of solar irradiation, the current of the Ta ₃ N ₅ photoelectrode was measured under a chopping condition in which a light was irradiated and blocked by using a shutter. While the light was chopped, the amount of current to the applied voltage was measured using the linear main prior art method. All potential values measured in the photoelectrochemical properties were converted to values relative to the reversible hydrogen electrode (RHE) using the following equation (1), and the pH of the electrolyte at the experimental condition was 13.8.

[Equation 1]

E (relative to RHE) = E (vs. Ag / AgCl) + 0.209 + 0.0591 x pH

In order to measure the photoelectrochemical properties of the Ta ₃ N ₅ -based photoelectrode, 0.1 M potassium hexacyanophelate (II) and 0.1 mM potassium hexacyanopyrate (III) were added to the electrolyte solution, scavenger) and photocurrent was measured. When using the hole scavenger can be a diagnostic assay for measuring the charge separation efficiency in the surface of Ta ₃ N ₅ C & T reaction Instead of the oxidation reaction of the scavenger to occur rapidly Ta ₃ N _5, and the light absorption efficiency of the catalytic material in the.

As can be seen from FIG. 5, the photocurrent density of the Ta ₃ N ₅ -based photoelectrode according to the aging time was compared at RHE 1.23 V, and as a result of the aging treatment for 1 hour, the comparative example 1 And a photocurrent higher than twice as high as in Example 2 in which aging treatment was performed for 2 hours was measured. In addition, in Examples 3 to 4 in which aging treatment was performed for 3 and 4 hours, it was confirmed that the photocurrent decreased as compared with Example 2. As a result, it can be seen that the best performance is obtained when the aging treatment time is 1 hour.

6, the photocurrent density values of the photoelectrode subjected to aging treatment for 1 hour (Example 1), 2 hours (Example 2), and 3 hours (Example 3) based on RHE 1.23 V are similar to each other, It can be confirmed that the performance of the photoelectrode (Example 1) subjected to the aging treatment for one hour is excellent.

On the other hand, in the case of Comparative Example 2 prepared as a control group, only polycrystalline tantalum (Ta) foil was used without a tantalum (Ta) coating solution, annealing was performed at 400 ° C. for 1 hour, and 900 ° C. in an electric furnace in which ammonia gas flowed at 100 sccm Deg.] C for 2 hours, but Ta ₃ N ₅ was not obtained, and photocurrent was not measured.

Therefore, according to the present invention, it is possible to provide tantalum nitride (Ta ₃ N ₅ ) with optimized photocatalytic performance through an aging treatment of a coating solution containing a tantalum precursor, It can be applied as a tantalum-based optical electrode.

Claims (12)

(a) aging a mixed solution obtained by mixing a tantalum precursor solution, an organic binder and an organic solvent;
(b) coating the aging-treated mixed solution on a substrate to form a thin film;
(c) oxidizing the thin film; And
(d) nitrating the oxidized thin film to form a photoelectrode coated with a thin film of tantalum nitride on the substrate,
Wherein the aging is performed at 40-70 DEG C for 40-80 minutes. delete delete The method according to claim 1,
Adding at least one precursor selected from a chromium precursor, a manganese precursor, a cobalt precursor, a nickel precursor, a rhodium precursor, and a molybdenum precursor to the tantalum precursor solution in an amount of 1-10 atomic percent relative to the tantalum precursor before the step (a) The method of manufacturing a tantalum nitride based optical electrode according to claim 1, The method according to claim 1,
Wherein the step (c) is performed at 300-500 < 0 > C. The method according to claim 1,
Wherein the step (d) is performed at 700-1000 < 0 > C. The method according to claim 1,
Wherein the tantalum precursor is in the form of one or more selected from the group consisting of chloride, bromide, iodide, nitrate, nitrite, sulfate, acetate, sulfite, acetylacetonate and hydroxide. Gt; The method according to claim 1,
Wherein the organic binder is at least one selected from the group consisting of ethyl cellulose, methyl cellulose, carboxy cellulose, nitrocellulose, methacrylic acid ester, acrylic acid ester, polyvinyl alcohol and polyvinyl butyral. Way. The method according to claim 1,
The organic solvent may be selected from the group consisting of alpha-terpineol, water, acetone, N-methyl-2-pyrrolidone, N, N'-dimethylformamide, N, N'-diethylformamide, dimethylsulfoxide, (2-ethoxyethanol, 2-ethoxyethanol, 2-methoxypropanol, tetrahydrofuran (THF), ethylene glycol, pyridine, N-vinylpyrrolidone Wherein at least one selected from the group consisting of silver, silver, silver, silver, silver, silver, silver, silver, silver, silver, silver, silver, The method according to claim 1,
Wherein the material of the substrate is one material selected from the group consisting of tantalum, quartz, alumina, and titanium. The method according to claim 1,
Wherein the thickness of the tantalum nitride thin film is 200-400 nm. The method according to claim 1,
Wherein the size of the tantalum nitride particles is 1-50 nm.

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