KR20180112300A - Photoelectrochemical cell electrode comprising metallic nanoparticles and method for manufacturing the same - Google Patents

Abstract

The present invention discloses a photoelectrochemistry cell electrode including a metal nanoparticle which has excellent water dissociation performance, and a manufacturing method thereof. The manufacturing method of a photoelectrochemistry cell electrode according to the present invention comprises: a step (a) of mixing a first solution in which a metal precursor is dissolved and a second solution in which a bismuth (Bi) precursor and a vanadium (V) precursor are dissolved; a step (b) of applying the mixed mixture on a substrate; and a step (c) of heat-treating the applied product. A metal nanoparticle having an average diameter of 10 nm or less is dispersed in the inside of a BiVO_4 thin film.

Description

TECHNICAL FIELD [0001] The present invention relates to a photoelectrochemical cell electrode comprising metal nanoparticles and a method of manufacturing the same. BACKGROUND ART < RTI ID = 0.0 > [0002]

The present invention relates to a photoelectrochemical cell electrode, and more particularly, to a photoelectrochemical cell electrode including metal nanoparticles and a method of manufacturing the same.

Much research is underway to effectively produce and consume renewable sources of energy such as solar, wind, marine, biomass, and hydrogen.

Among renewable energy, hydrogen energy (H ₂ ) is produced from water (H ₂ O) and sustainable, and can be regenerated after it is used as fuel. In addition, it is eco-friendly because it does not emit substances that cause air pollution such as sulfur dioxide (SO _x ), nitric acid gas (NO _x ), and dust as well as carbon dioxide during combustion.

Hydrogen energy is easily transported in the form of high pressure gas or liquid hydrogen, and has excellent storability, and is used in various fields such as hydrogen automobiles and fuel cells throughout the industry.

Electrolysis of water is used to produce hydrogen energy. Electrolysis of water is simple in process, high in reliability, and capable of mass production of hydrogen energy, but has a problem of high cost of electric energy used in electrolysis.

On the other hand, a water splitting method using a photoelectrochemical cell (PEC cell) using solar energy is proceeding in order to effectively decompose water at low cost.

As shown in FIG. 1, in a water decomposition method using a photoelectrochemical cell, an electron-hole pair (EHP) generated by a photon induces the generation of hydrogen gas and oxygen gas through oxidation and reduction reaction of water .

2H ₂ O + 4h ⁺ → 4H ⁺ + O ₂ (reaction at the photoanode)

4H ⁺ + 4e ^- ? 2H ₂ (reaction in photocathode)

2H ₂ O → 2H ₂ + O ₂ (hydrogen production through photoelectrochemical decomposition)

A photoelectrochemical cell (PEC cell) basically consists of an oxidizing electrode, a reducing electrode, and an aqueous solution that acts as an electrolyte between the two electrodes.

Electrodes need to operate stably in aqueous solutions in which various chemicals are dissolved, so they need good chemical resistance and should be able to decompose water by absorbing sunlight to generate excited electrons and hole pairs.

Recently, studies have been actively conducted to form electrodes using metal nanoparticles so as to obtain water-decomposable electrodes by using oxides having excellent chemical stability and to obtain improved performance by supporting them. However, this is because the metal nanoparticles are mainly present on the surface of the photoelectrode and thus the bonding force between the photoelectrode and the metal nanoparticles is lowered, and the free electrons are lost at the interface between the photoelectrode and the metal nanoparticles, There is a problem that the performance is deteriorated.

Accordingly, in order to solve such a problem, there is a demand for an electrode which increases the light absorption efficiency of the oxide electrode and has excellent water decomposition ability.

A related art related to the present invention is Korean Patent Registration No. 10-1110364 (registered on Jan. 19, 2012), which discloses an electrode of a dye-sensitized solar cell using metal nanoparticles and a method for producing the same .

An object of the present invention is to provide a photoelectrochemical cell electrode having excellent water decomposition ability.

It is another object of the present invention to provide a method of manufacturing a photoelectrochemical cell electrode which is easy to manufacture.

According to an aspect of the present invention, there is provided a method of manufacturing a photoelectrochemical cell electrode, comprising: (a) forming a first solution in which a metal precursor is dissolved, a second solution in which a bismuth (Bi) precursor and a vanadium Mixing; (b) applying the mixed mixture onto a substrate; And (c) heat treating the coated product. The metal nanoparticles having an average particle diameter of 10 nm or less are distributed in the BiVO ₄ thin film by the heat treatment.

In the step (a), the mixing may be performed at 100 ° C or lower to form metal nanoparticles.

The metal may include silver (Ag).

In the step (a), the first solution in which the metal precursor is dissolved may include 0.1 to 30 parts by weight of a metal precursor based on 100 parts by weight of the bismuth (Bi) precursor and the vanadium (V) precursor.

The application may be carried out by spray coating, bar coating or spin coating.

The heat treatment may be performed at 200 to 600 ° C.

The thickness of the BiVO ₄ thin film may be 0.01 to 10 탆.

According to another aspect of the present invention, there is provided a photoelectrochemical cell electrode according to the present invention, wherein metal nanoparticles having an average particle diameter of 10 nm or less are distributed in a BiVO ₄ thin film.

The metal may include silver (Ag).

The electrode may include 0.1 to 30 parts by weight of metal nanoparticles relative to 100 parts by weight of the BiVO ₄ thin film.

The thickness of the BiVO ₄ thin film may be 0.01 to 10 탆.

The photoelectrochemical cell electrode according to the present invention includes metal nanoparticles having a size of several nanometers in the BiVO ₄ thin film, so that the plasmonic effect generated in the metal nanoparticles is applied, An electrode can be formed.

The photoelectrochemical cell electrode of the present invention is characterized in that it is easy to form the electrode in a thin film form in that the manufacturing process is performed by a solution process.

1 is a schematic view showing a water decomposition reaction using a photoelectrochemical cell.
2 is a flowchart illustrating a method of manufacturing a photoelectrochemical cell electrode according to the present invention.
3 is a schematic view showing a spin coating process.
FIG. 4 is a TEM photograph of a photoelectrochemical cell electrode in which silver nanoparticles (Ag NPs) are dispersed in a BiVO ₄ thin film according to the present invention.
5 is a TEM-energy dispersive X-ray spectrometer (EDS) mapping of photoelectrochemical cell electrodes according to the present invention.
6 is a graph showing an X-ray diffraction (XRD) pattern of the photoelectrochemical cell electrode according to the present invention.
7 is a UV-vis spectrum according to the plasmonic effect of silver nanoparticles according to the present invention.
8 is a graph showing a result of measuring the performance of the photoelectrochemical cell according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, a photoelectrochemical cell electrode including metal nanoparticles according to a preferred embodiment of the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

The present invention provides a photoelectrochemical cell electrode having excellent water decomposition ability by using a plasmonic effect generated in metal nanoparticles.

The plasmonic effect is a phenomenon in which free electrons collectively resonate to generate a strong electric field by electromagnetic waves such as solar energy applied to metal nanoparticles. Due to the plasmonic effect of the metal nanoparticles, the wavelength range of the absorbable light and the absorption efficiency are increased, so that more solar energy can be absorbed. In addition, by reducing the frequency of recombination of electron hole pairs (EHP) generated inside the photoelectrochemical cell electrode due to the electric field around the metal nanoparticles, and by supplying free electrons in the metal nanoparticles to the electrode, Can be improved.

The manufacturing process of the present invention is effected by a solution process, which facilitates the chemical bonding between the metal nanoparticles and the electrode and facilitates formation of the electrode in the form of a thin film. Further, since the metal nanoparticles formed by the manufacturing process proposed in the present invention are not limited to only the surface of the electrode, but are uniformly distributed within the thin film electrode, the efficiency of absorption of the solar energy in all portions of the electrode .

As shown in FIG. 1, the photoelectrochemical cell (PEC cell) is composed of an oxidizing electrode, a reducing electrode, and an electrolyte. When solar energy having an energy of band gap energy or more enters into a semiconductor optical electrode (oxidizing electrode or reducing electrode), an electron hole pair (EHP) is formed in the semiconductor due to the photoelectric effect, The hole pairs are separated by band bending occurring inside the semiconductor and at the semiconductor-electrolyte interface.

The separated holes (h ⁺ ) oxidize water (H ₂ O) at the oxidized electrode-electrolyte interface to produce proton ions (H ⁺ ) and generate oxygen gas (O ₂ ). The separated electrons e ^- move to the reduction electrode along the external circuit and generate hydrogen gas (H ₂ ) by reducing the proton ions (H ⁺ ) transferred through the electrolyte at the reducing electrode-electrolyte interface.

Water decomposition using a PEC cell can produce renewable hydrogen energy continuously. Since oxygen is produced along with hydrogen energy, the oxygen can be used for decomposing and purifying organic matter.

FIG. 2 is a flowchart illustrating a method of manufacturing a photoelectrochemical cell electrode including metal nanoparticles according to the present invention.

Referring to FIG. 2, a method of manufacturing a photoelectrochemical cell electrode includes a step S110 of mixing a first solution and a second solution, a step of applying S120, and a step of performing a heat treatment S130.

Mixing the first solution and the second solution (S110)

First, a first solution in which a metal precursor is dissolved is prepared.

The metal is preferably containing a (Ag), the metal precursor is silver nitrate (AgNO _3), perchloric acid is (AlClO _4), acid is (AgClO _3), carbonate (Ag ₂ CO _3), silver sulfate (Ag ₂ SO ₄ ), silver chloride (AgCl), silver bromide (AgBr) and fluorine silver (AgF).

The metal precursor may be dissolved in an organic solvent such as dimethylformamide (DMF, C ₃ H ₇ NO), ethyl alcohol or tetrahydrofuran (THF, C ₄ H ₈ O) to form a first solution, 1 solution may be added to the solution, but not limited thereto.

The metal precursor may be added so as to be uniformly dispersed in the first solution, and the first solution preferably contains 0.1 to 30 parts by weight of the metal precursor relative to 100 parts by weight of the bismuth (Bi) precursor and the vanadium (V) , And more preferably 5 to 20 parts by weight.

When the content of the metal precursor is less than 0.1 part by weight, the density of the metal nanoparticles formed in the electrode is low and the plasmonic effect does not sufficiently take place, so it is difficult to expect the improved water decomposition efficiency of the electrode. On the contrary, when the amount exceeds 30 parts by weight, the specific gravity of the photoelectrode (semiconductor) occupied by the final electrode is reduced due to an increase in the content of the metal precursor, so that the absorption of light is reduced and the water decomposition efficiency of the electrode is lowered. Also, as the content of the metal precursor increases, the size of the metal nanoparticles formed increases and the uniformity of the distribution of the particles in the electrode decreases, thereby increasing the recombination ratio of the electron-hole pairs and reducing the electrode efficiency.

Therefore, the content of the metal precursor in the first solution is preferably 0.1 to 30 parts by weight, more preferably 5 to 20 parts by weight. When the content is 5 to 20 parts by weight, metal nanoparticles having an average particle diameter of 10 nm or less are uniformly distributed within the electrode without aggregation. Accordingly, since the interfacial area between the photoelectrode (semiconductor) and the metal nanoparticle can have a maximum value, it is possible to prevent recombination of electrons and holes due to the plasmonic effect, (Semiconductor) can be maximized

Next, a second solution in which the bismuth (Bi) precursor and the vanadium (V) precursor are dissolved is provided. The bismuth precursor: vanadium precursor may be mixed in a weight ratio of 1: 1 to 1: 3 or in a weight ratio of 1: 1 to 3: 1, but is not limited thereto.

Bismuth (Bi) precursor is nitrate, bismuth _{(Bi (NO 3) 3)} , chloride, bismuth (BiCl _3), and the like may be used, vanadium (V) is vanadyl acetylacetonate (VO (acac) ₂₎ as a precursor, Ammonium metavanadate (NH ₄ VO ₃ ) and the like can be used.

The bismuth precursor and the vanadium precursor may be dissolved in an organic solvent such as ethyl alcohol or acetylacetone to form a second solution. Acetic acid may be further added to the second solution, but the present invention is not limited thereto.

The first solution and the second solution may be mixed and stirred at a temperature of 25 to 100 ° C for about 5 minutes to 5 hours. In the course of heating and mixing the first solution and the second solution, metal nanoparticles . Accordingly, the mixture in which the first solution and the second solution are mixed includes the metal nanoparticles, the metal precursor, the bismuth precursor, and the vanadium precursor.

The mixing and agitation time can be controlled by considering the viscosity and the degree of dispersion of the metal nanoparticles. When the mixing condition (temperature and time) exceeds 5 hours and exceeds 100 ° C, the reduction rate from the metal precursor to the metal nanoparticles is increased by the high temperature and long-time agitation, and the size of the nanoparticles becomes larger than tens of nanometers . At the same time, the size of the metal nanoparticles may become uneven. Conversely, if the mixing condition is less than 5 minutes and less than 25 ° C, insufficient reduction and stirring conditions are insufficient to form the metal nanoparticles in the step (S110) of mixing the first solution and the second solution, Aggregation of nanoparticles may occur.

As described above, the metal nanoparticles can be formed in the mixing process by heating. When the solution is mixed under the preferable mixing conditions, the metal nanoparticles are homogeneously distributed in the BiVO ₄ thin film through the application and heat treatment process can do.

In step S120,

Next, the mixed mixture is applied on a substrate.

Coating may be carried out by spray coating, bar coating or spin coating, It is possible to form a thin thin film.

When the electrode is formed as a thin film, if the thickness of the electrode is less than 0.01 탆, the electrode can not absorb light sufficiently, and light is transmitted therethrough, resulting in reduction of the water decomposition efficiency of the electrode. Conversely, when the thickness exceeds 10 탆, the probability that electrons or holes separated from the inside of the electrode are lost due to recombination occurring before the interface reaches the electrode-electrolyte interface in order to reduce or oxidize the water is abrupt Resulting in a sharp decrease in the water decomposition efficiency of the electrode.

Therefore, the thickness of the electrode formed of the thin film is preferably 0.01 to 10 mu m.

However, since the thickness of the electrode in which the above-described problem occurs is a result of a combination of physical properties such as a light absorption coefficient and a carrier mobility of a material constituting the electrode, The range may vary depending on the substance. In addition, the thickness of the electrode can be varied according to the size, density, etc. of the metal nanoparticles distributed inside the electrode.

Spray coating is a commonly used coating method in which a coating liquid is sprayed onto a coating material. Bar coating is a coating method in which a coating liquid is formed on a substrate while a coating liquid and a wire bar are moved together using a wire bar having a uniform thickness. This is easy to form a thin film having a thickness of 100 μm or less. As shown in FIG. 3, the spin coating is a coating method in which the coating liquid is dropped onto a substrate and then rotated at a high speed to spread thinly.

As described above, in the present invention, the precursor-dispersed mixture is applied by spray coating, bar coating or spin coating to form a thin film in which the metal nanoparticles are uniformly dispersed therein.

Also, as shown in FIG. 3, spray coating, bar coating, and spin coating are applicable to a large area production process, and they are usable in various fields and have excellent process flexibility.

The heat treatment step (S130)

Next, the coated product is heat-treated and crystallized.

The heat treatment is preferably performed at a temperature of about 200 to 600 ° C, and more preferably, at a temperature of 400 to 500 ° C so that the sintering of the precursor is completed.

When the heat treatment is performed at a temperature lower than 200 캜, the sintering of the precursor and the removal of organic impurities including the solvent are not sufficiently performed, so that the crystallinity of the electrode is decreased and impurities may remain in the electrode. On the other hand, when the temperature exceeds 600 ° C., crystallinity is reduced by volatilization of elements such as Bi constituting the electrode, and oxidation of metal occurs on the surface of the metal nanoparticles, so that a thin metal oxide film can be formed around the nanoparticles. All of these phenomena lead to a reduction in electrode water decomposition efficiency.

By the heat treatment, the metal nano-particles having an average particle diameter of 10 nm or less can be uniformly dispersed in the BiVO ₄ thin film without aggregation.

4, I is the surface of the electrode material of the nanoparticles have a structure in which the surrounding BiVO _4, BiVO _4, which thin film is on the inside means that the nano-particles are present. That is, as a result of the heat treatment, a heterostructure of metal nanoparticles and BiVO ₄ is formed inside the electrode. 4, the characteristics of the photoelectrochemical cell electrode formed through the manufacturing method disclosed in the present patent can be confirmed.

First, it can be seen that the metal nanoparticles having a particle diameter of less than 10 nm are not limited to the surface of the electrode but are uniformly distributed in the electrode. As a result, the plasmonic effect generated in the metal nanoparticles improves the absorption efficiency of the solar energy in all parts of the electrode.

Another feature is that the photoelectrode (semiconductor) and the metal nanoparticles are in contact through chemical bonding, and since a strong electric field is formed by the plasmonic effect at the contact interface, electrons (electrons) - It is possible to prevent recombination of hole pairs and to introduce free electrons in the metal nanoparticles into the photoelectrode (semiconductor).

Thus, through this structural feature, the metal nanoparticles efficiently absorb light in the visible light region, electrons excited by the absorbed light enter the electrode, electrons and holes move to the electrode-electrolyte interface It is used directly in the water decomposition reaction. Thus, photoelectrochemical cell electrodes can exhibit improved water degradation performance.

The BiVO ₄ thin film may be formed to a thickness of 0.01 to 10 탆 in consideration of the size of the metal nanoparticles, etc. When the thickness of the electrode is less than 0.01 탆, BiVO ₄ does not sufficiently absorb light, So that the water decomposition efficiency is reduced. Conversely, if the thickness exceeds 10㎛, BiVO ₄ BiVO ₄ in order to oxidize the electron is separated from the water inside-electrolyte in the process of moving the interface to reach the interface recombination loss is suddenly elevated probability to occur before do. As a result, the water decomposition efficiency of the BiVO ₄ device is drastically reduced.

As described above, in the method of manufacturing the photoelectrochemical cell electrode of the present invention, the first solution containing the metal precursor, the second solution containing the bismuth precursor and the vanadium precursor are mixed and formed into a thin film and heat-treated.

According to this manufacturing method, it is possible to manufacture a thin film in which metal nanoparticles of several nanometers in size are uniformly dispersed in the inside, and in particular, to improve the water decomposition performance of the electrode by the plasmonic effect generated in metal nanoparticles It is effective.

The photoelectrochemical cell electrode according to the present invention is characterized in that metal nanoparticles having an average particle diameter of 10 nm or less are contained in the BiVO ₄ thin film.

As described above, the metal may include silver (Ag), and the thickness of the BiVO ₄ thin film may be 0.01 to 10 탆.

The photoelectrochemical cell electrode of the present invention preferably contains 0.1 to 30 parts by weight of metal nanoparticles per 100 parts by weight of the BiVO ₄ thin film, more preferably 5 to 20 parts by weight.

When the content of the metal nanoparticles is less than 0.1 part by weight, the density of the metal nanoparticles formed in the electrode is low, and the plasmonic effect does not sufficiently take place, so that it is difficult to expect an improved water decomposition efficiency of the electrode. On the other hand, if the amount of the metal nanoparticles is greater than 30 parts by weight, the specific gravity of the photoelectrode (semiconductor) occupied by the final electrode is reduced, so that the absorption of light decreases and the water decomposition efficiency of the electrode decreases. Also, as the content of the metal nanoparticles increases, the size of the formed metal nanoparticles increases and the uniformity of the distribution of the particles in the electrode decreases, thereby increasing the recombination ratio of the electron-hole pairs and reducing the electrode efficiency.

The photoelectrochemical cell electrode including the metal nanoparticles and the manufacturing method thereof will be described in detail as follows.

1. Manufacture of electrodes

Example

First, a first solution in which AgNO ₃ was dissolved in DMF was prepared, and a second solution in which VO (acac) ₂ and Bi (NO ₃ ) ₃ .5H ₂ O were dissolved in acetylacetone was prepared.

The content of AgNO ₃ in the first solution is 5, 10, 15 and 20 parts by weight of AgNO ₃ per 100 parts by weight of VO (acac) ₂ and Bi (NO ₃ ) ₃ .5H ₂ O, respectively.

Next, the prepared first solution and second solution were mixed and stirred at 35 캜 for 10 minutes to prepare a mixture, and the mixture was coated on a conductive glass substrate using spin coating.

Next, the resultant coating heat treatment at 500 ℃ for 2 hours, thereby producing an electrode including a thin film having a thickness of BiVO ₄ 0.2㎛.

It was confirmed that metal nanoparticles having an average particle diameter of 10 nm or less were dispersed in the BiVO ₄ thin film prepared by varying the content of AgNO ₃ .

2. Photoelectric chemical cell manufacturing

A Pt wire was used as a counter electrode of the BiVO ₄ oxidizing electrode to evaluate the performance of the manufactured photoelectrochemical cell. The two electrodes were placed in a quartz electrolytic cell customized for photoelectrochemical cell performance evaluation, A photoelectrochemical cell was fabricated by filling electrolyte (pH 9.3) in which Na ₂ SO ₄ (0.5 M) and Na ₂ SO ₃ (0.5 M) were dissolved in the electrolytic bath.

3. Property evaluation method and result

6 to Ag-BVO described in Figure 8 is inside BiVO ₄ denotes a thin film electrode which is dispersed nanoparticles, Pristine BVO is the BiVO ₄ thin film refers to the electrode that do not contain nanoparticles. In addition, Ag-BVO (4, 8, 12, 16 mM) was prepared by adding 5, 10, 15 and 20 parts by weight of silver precursor to 100 parts by weight of the entire bismuth and vanadium precursor Point.

FIG. 5 shows the results of TEM-energy dispersive X-ray spectrometer (EDS) mapping of photoelectrochemical cell electrodes. The existence of silver nanoparticles can be confirmed through composition analysis.

It can be seen from the results of FIG. 5 that vanadium, bismuth and silver nanoparticles are uniformly distributed and that a BiVO ₄ thin film containing silver nanoparticles (Ag NPs) is formed on the surface of FTO (F-doped SnO ₂ ) .

6 is a graph showing an X-ray diffraction (XRD) pattern of the photoelectrochemical cell electrode according to the present invention.

6, the diffraction peak of Pristine BVO is composed of monoclinic BVO (vertical dotted line) and the peak due to FTO, and the diffraction peak of Ag-BVO is in the case of Pristine BVO Very similar results show that no other phase other than monoclinic BVO is formed.

FIG. 7 shows UV-vis spectra according to the plasmonic effect of the silver nanoparticles of the present invention, indicating that Ag-BVO has a higher light absorption than Pristine BVO.

In particular, Ag-BVO (16 mM) has higher light absorption than other electrodes because the content of silver nanoparticles is increased.

Therefore, it can be confirmed that the metal nanoparticles efficiently absorb the light of the sunlight, in particular, the visible light region, because the silver nanoparticles resonate with the solar light energy to generate the plasmonic effect. As a result, it can be seen that the water decomposition performance of the electrode is improved by the improved light absorption of the electrode formed with the metal nanoparticles.

8 is a graph showing a result of measuring the performance of a photoelectrochemical cell electrode according to the present invention. Voltage and photocurrent density were measured using Autolab PGSTAT302N.

As shown in FIG. 8, the photocurrent density of Ag-BVO versus the photocurrent density of Pristine BVO is much higher than that of Pristine BVO.

The photocurrent density increased about 1.5 times in Ag-BVO (4mM) compared to the current density of Pristine BVO at 1.23V based on RHE.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is to be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (11)

(a) mixing a first solution in which a metal precursor is dissolved, a second solution in which a bismuth (Bi) precursor and a vanadium (V) precursor are dissolved;
(b) applying the mixed mixture onto a substrate; And
(c) heat treating the coated product,
Wherein the metal nanoparticles having an average particle size of 10 nm or less are distributed in the BiVO ₄ thin film by the heat treatment.
The method according to claim 1,
In the step (a), the mixing is performed at 100 ° C or less so as to form metal nanoparticles.
The method according to claim 1,
Wherein the metal comprises silver (Ag).
The method according to claim 1,
In the step (a), the first solution, in which the metal precursor is dissolved,
Wherein the metal precursor comprises 0.1 to 30 parts by weight of a metal precursor based on 100 parts by weight of a bismuth (Bi) precursor and a vanadium (V) precursor.
The method according to claim 1,
Wherein the application is performed by spray coating, bar coating or spin coating.
The method according to claim 1,
Wherein the heat treatment is performed at 200 to 600 ° C.
The method according to claim 1,
Wherein the BiVO ₄ thin film has a thickness of 0.01 to 10 탆.
Wherein the metal nanoparticles having an average particle diameter of 10 nm or less are distributed inside the BiVO ₄ thin film.
9. The method of claim 8,
Wherein the metal comprises silver (Ag).
9. The method of claim 8,
Wherein the electrode comprises 0.1 to 30 parts by weight of metal nanoparticles per 100 parts by weight of the BiVO ₄ thin film.
9. The method of claim 8,
Wherein the thickness of the BiVO ₄ thin film is 0.01 to 10 μm.

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