KR102278568B1 - Photoelectrochemical cell producing h2o2 at anode and cathode simultaneously and method of fabricating same - Google Patents

Abstract

Disclosed are a photoelectrochemical cell including a photoanode doped with a dopant and a cathode including an anthraquinone-supported carbon material, a method for manufacturing the same, and a method for simultaneously producing hydrogen peroxide using the same. The photoelectrochemical cell may include: a photoanode including dopant-doped bismuth vanadate (BiVO _{4 );} and a cathode including a carbon material and a compound represented by Structural Formula 1 supported on the carbon material; thereby increasing the conversion selectivity to hydrogen peroxide during the reaction of the photoanode and the cathode. Hydrogen peroxide can be produced at the same time even when no external voltage is applied.
[Structural Formula 1]

Description

A photoelectrochemical cell that simultaneously produces hydrogen peroxide at an anode and a cathode, and a method for manufacturing the same {PHOTOELECTROCHEMICAL CELL PRODUCING H2O2 AT ANODE AND CATHODE SIMULTANEOUSLY AND METHOD OF FABRICATING SAME}

The present invention relates to the development of an electrode material and system for solar conversion energy production, and more particularly, a photoelectrochemical cell including a dopant-doped photoanode and a cathode including an anthraquinone-supported carbon material, and the It relates to a manufacturing method and a method for simultaneous production of hydrogen peroxide using the same.

Hydrogen peroxide is widely applied in chemical and environmental processes as a carbon-free energy source and an environmentally friendly oxidizing agent. The existing hydrogen peroxide industrial process is a process that requires hydrogen gas, harmful organic solvents, and precious metal catalysts, which has a high production cost and causes environmental pollution. The generation of hydrogen peroxide using the photoelectrochemical method is an eco-friendly and low-cost production method that uses only sunlight, oxygen and water as external energy.

Hydrogen peroxide production can be achieved through the oxidation of water or the reduction of oxygen. In this process, both reactions take place through a selective two-electron reaction. However, oxidation reactions compete with hydroxyl radicals and oxygen evolution reactions other than conversion to hydrogen peroxide. In addition, in the reduction reaction, in addition to the reduction of oxygen, it competes with the hydrogen production reaction due to the reduction of water. Therefore, in order to effectively produce hydrogen peroxide, it is required to develop a catalyst that promotes a reaction for selectively converting hydrogen peroxide in both reactions.

The photoelectrochemical method is a method capable of simultaneously inducing oxidation and reduction reactions using appropriate two electrode materials. Bismuth vanadate is used as a photoelectrode for photoelectrochemical processes because of its excellent selectivity for conversion to hydrogen peroxide through water oxidation. However, in order to achieve a more practical bismuth vanadate-based photoelectrochemical hydrogen peroxide production method, a high level of production efficiency must be secured, and stability must be improved to prevent dissolution during long-term operation on hydrogen carbonate. In addition, there is a problem in that stability for long-term operation is weak due to the low hydrogen peroxide conversion selectivity of bismuth vanadate and the problem of dissolution during the decomposition reaction and reaction of hydrogen peroxide generated on the surface.

An object of the present invention is to solve the above problems, and a bismuth vanadate photoelectrode with long-term stability based on improved electrochemical properties and improved hydrogen peroxide conversion selectivity for the production of hydrogen peroxide through oxygen reduction in reduction reactions as well as oxidation reactions. To provide a photoelectrochemical cell and a method for manufacturing the same using

In addition, a photoelectrochemical cell maximizing the efficiency of the photoelectrochemical method by developing a system for simultaneous production of hydrogen peroxide based on an oxygen reduction reaction in the bismuth vanadate photoelectrode and the opposite electrode, a method for manufacturing the same, and a method for simultaneously producing hydrogen peroxide using the same is to provide

According to an aspect of the present invention, a dopant-doped bismuth vanadate (BiVO ₄ ) including a photoanode (photoanode); and a cathode including a carbon material and a compound represented by Structural Formula 1 supported on the carbon material; a photoelectrochemical (PEC) cell comprising a.

[Structural Formula 1]

In Structural Formula 1,

R is a hydrogen atom, a carboxyl group, a sulfonic acid group, an amino group, or a hydroxy group.

In addition, the photoanode may be surface-treated with phosphate.

In addition, by surface-treating the bismuth vanadate with phosphate, the photoanode may form phosphorus (P) on the bismuth vanadate.

In addition, the dopant may include at least one selected from the group consisting of molybdenum (Mo), tungsten (W), and chromium (Cr).

In addition, the carbon material is a single-walled carbon nanotube (SWCNT), a double-walled carbon nanotube (double-walled carbon nanotube, DWCNT), a multi-walled carbon nanotube (Multi-walled carbon nanotube, MWCNT), It may include at least one selected from the group consisting of carbon nanofiber (CNF), graphene oxide (GO), and carbon black.

In addition, a molar ratio (D/BV, mol/mol) of the dopant (D) to the bismuth vanadate (BV) may be 1 to 20.

In addition, the photoanode may further include a substrate, and bismuth vanadate doped with the dopant may be formed on the substrate.

In addition, the cathode may further include carbon paper, and the carbon material and the compound represented by Structural Formula 1 may be formed on the carbon paper.

According to another aspect of the present invention, (a) manufacturing a photoanode comprising bismuth vanadate doped with a dopant; (b) preparing a cathode including a carbon material and a compound represented by Structural Formula 1 supported on the carbon material; and (c) manufacturing a photoelectrochemical cell including the photoanode, the separator, and the cathode.

[Structural Formula 1]

In Structural Formula 1,

R is a hydrogen atom, a carboxyl group, a sulfonic acid group, an amino group, or a hydroxy group.

In addition, the step (a) comprises the steps of (a-1) preparing a precursor solution including a bismuth precursor, a vanadium precursor, and a dopant precursor; and (a-2) drying and heat treating the precursor solution to prepare dopant-doped bismuth vanadate.

In addition, the heat treatment of step (a-2) may be performed at 300 to 800 ℃.

In addition, the method for producing photoelectrochemical electricity may further include (a-2') surface-treating the photoanode with a solution containing phosphate, drying, and heat treatment after step (a-2). can

In addition, the heat treatment of step (a-2') may be performed at 100 to 500 ℃.

In addition, the bismuth precursor includes at least one selected from the group consisting _{of Bi(NO 3} ) ₃ ·5H ₂ O, BiCl ₃ , BiClO ₅ ·xH ₂ O and BiF _{3 , and the vanadium precursor is OV(C 5} H ₇ O ₂ ) ₂ , OV(OCH(CH ₃ ) ₂ ) ₃ , OV(OC ₃ H ₇ ) ₃ and VOCl ₃ may include one or more selected from the group consisting of.

In addition, the dopant precursor may include at least one selected from the group consisting of a molybdenum precursor, a tungsten precursor, and a chromium precursor.

In addition, the step (b) is (b-1) preparing a mixed solution by mixing the compound represented by Structural Formula 1 and a carbon material; and (b-2) drying and heat-treating the mixed solution to prepare a cathode including a carbon material on which the compound represented by Structural Formula 1 is supported.

In addition, the heat treatment of step (b-2) may be performed at 50 to 100 ℃.

According to another aspect of the present invention, (1) providing the photoelectrochemical cell; And (2) the photoanode oxidizes water under light irradiation to produce hydrogen peroxide (H ₂ O ₂ ), and the cathode reduces oxygen to produce hydrogen peroxide; a method for producing hydrogen peroxide is provided.

In addition, the oxidation and reduction may be performed simultaneously.

In addition, the photoelectrochemical cell may produce hydrogen peroxide with electrical energy generated from solar energy.

The photoelectrochemical cell of the present invention _{includes a photoanode containing bismuth vanadate (BiVO 4} ) doped with a dopant, and thus has excellent conversion selectivity to hydrogen peroxide through water oxidation, and further By surface-treating the node with phosphate, the stability is improved, and ultimately, the production of hydrogen peroxide through a photoelectrochemical process has an excellent effect.

In addition, the photoelectrochemical cell of the present invention includes a cathode to which an anthraquinone derivative is bonded, thereby completely suppressing hydrogen production through water decomposition, a competitive reaction at the cathode, and generating hydrogen peroxide in a wide voltage range.

In addition, the photoelectrochemical cell of the present invention can simultaneously produce hydrogen peroxide even under a condition in which no external voltage is applied through the combination of the photoanode and the cathode.

These drawings are for reference in describing an exemplary embodiment of the present invention, and the technical spirit of the present invention should not be construed as being limited to the accompanying drawings.
1 shows a schematic diagram of a photoelectrochemical cell according to an embodiment of the present invention.
FIG. 2a shows an SEM photograph of the photoanode manufactured according to Example 1. FIG.
FIG. 2b shows XRD patterns of photoanodes prepared according to Examples 1 to 3 and Comparative Example 1. FIG.
FIG. 2c shows XPS spectra of O 1s for the photoanodes prepared according to Examples 1 to 3 and Comparative Example 1. FIG.
Figure 2d shows the FTIR spectra of anthraquinone-carbon nanotube (AQ-CNT), carbon nanotube (CNT) and anthraquinone (Pure AQ) samples.
3A shows the photoelectrochemical characteristics of the photoanodes prepared according to Examples 1, 5, 6 and Comparative Example 1 and hydrogen peroxide production efficiency according to voltage.
3B shows the photoelectrochemical characteristics and the hydrogen peroxide production efficiency for each voltage of the photoanodes prepared according to Examples 1 to 3 and Comparative Example 1. FIG.
FIG. 3c shows a Mott-Schottky (MS) graph of the photoanodes manufactured according to Examples 1 to 3 and Comparative Example 1 measured at a fixed frequency of 1 kHz.
3D shows Nyquist plots of the photoanodes prepared according to Examples 1 to 3 and Comparative Example 1. FIG.
4A shows the amount of hydrogen peroxide decomposition according to time of the photoanode prepared according to Examples 1 to 3 and Comparative Example 1. FIG.
4B shows the photocurrent flow and the amount of generated electric charge during the measurement of the amount of hydrogen peroxide decomposition with time in the photoanodes manufactured according to Examples 1 to 3 and Comparative Example 1. FIG.
FIG. 4c shows a value obtained by dividing the amount of hydrogen peroxide decomposition with time of the photoanodes manufactured according to Examples 1 to 3 and Comparative Example 1 by the amount of generated electric charge.
5a shows cyclic voltammograms (CVs) of cathodes prepared according to Example 7, Comparative Example 2 and Comparative Example 3. FIG.
5B shows Nyquist plots of cathodes prepared according to Example 7, Comparative Example 2, and Comparative Example 3. FIG.
Figure 5c shows Koutecky-Levich plots of anthraquinone-carbon nanotube (AQ-CNT) and carbon nanotube (CNT) powder.
6A shows the photoelectrochemical characteristics and the hydrogen peroxide or oxygen generation efficiency for each voltage of the photoelectrochemical cell manufactured according to Device Example 1. FIG.
6B shows the production and efficiency of hydrogen peroxide or hydrogen for each voltage of the photoelectrochemical cell manufactured according to Device Example 1 and Device Comparative Example 1. FIG.
7A shows the photoelectrochemical characteristics of the photoelectrochemical cells prepared according to Device Examples 1 and 2 and the hydrogen peroxide production efficiency for each voltage.
7B shows the amount of photocurrent generation and the amount of hydrogen peroxide generated according to time of the photoelectrochemical cells prepared according to Device Examples 1 and 2 and Device Comparative Example 1. FIG.
7c shows the photoelectrochemical properties of the photoelectrochemical cells prepared according to Device Examples 1 and 2 for 100 hours.
7D shows a surface SEM image of the photoanode used in Device Example 1 after 100 hours of reaction.
7e shows Bi 4f and V 2p XPS spectra before and after 100 hours of reaction of the photoanodes used in Device Examples 1 and 2;
7f shows P 2p and Sn 3d XPS spectra before and after 100 hours of reaction of the photoanode used in Device Examples 1 and 2;
8A shows the photoelectrochemical properties of Examples 1, 6, 7, and Comparative Examples 2 and 3;
8B shows the photoelectrochemical characteristics of Device Examples 1 and 2 and Device Comparative Examples 1 and 2 in the absence of an externally applied voltage.
8C shows the amount of photocurrent generated and the amount of hydrogen peroxide generated according to time in Device Examples 1 and 2 in the absence of an externally applied voltage.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art to which the present invention pertains can easily carry out the present invention.

However, the following description is not intended to limit the present invention to specific embodiments, and when it is determined that a detailed description of a related known technology may obscure the gist of the present invention in describing the present invention, the detailed description thereof will be omitted. .

The terminology used herein is only used to describe specific embodiments, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, element, or combination thereof described in the specification exists, but is one or more other features or It should be understood that the existence or addition of numbers, steps, acts, elements, or combinations thereof, is not precluded in advance.

In addition, terms including an ordinal number such as first, second, etc. to be used below may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

In addition, when it is said that a component is "formed" or "stacked" on another component, it may be formed or laminated directly attached to the front surface or one surface on the surface of the other component. It should be understood that other components may be present in the .

Hereinafter, a photoelectrochemical cell including a dopant-doped photoanode and a cathode including an anthraquinone-supported carbon material of the present invention, a method for manufacturing the same, and a method for simultaneous production of hydrogen peroxide using the same will be described in detail. However, this is provided as an example, and the present invention is not limited thereto, and the present invention is only defined by the scope of the claims to be described later.

1 shows a schematic diagram of a photoelectrochemical cell according to an embodiment of the present invention.

Referring to Figure 1, the present invention is a dopant-doped bismuth vanadate (BiVO ₄ ) A photoanode (photoanode) containing; and a cathode including a carbon material and a compound represented by Structural Formula 1 supported on the carbon material; provides a photoelectrochemical (PEC) cell comprising a.

[Structural Formula 1]

In Structural Formula 1,

R is a hydrogen atom, a carboxyl group, a sulfonic acid group, an amino group, or a hydroxy group.

In the cathode, the compound represented by Structural Formula 1 is anchored on a carbon material, and in this case, R in Structural Formula 1 may maintain the form of a hydrogen atom, a carboxyl group, a sulfonic acid group, an amino group, or a hydroxyl group.

In addition, the photoanode may be surface-treated with phosphate.

In addition, by surface-treating the bismuth vanadate with phosphate, the photoanode may form phosphorus (P) on the bismuth vanadate.

As phosphorus (P) is formed on the bismuth vanadate by surface treatment of the photoanode with phosphate, the photoanode stability, photocurrent generation, and hydrogen peroxide conversion selectivity are improved. In addition, even if the reaction time is long, the photoanode stably generates a photocurrent and has the effect of having a high hydrogen peroxide production amount.

In addition, the dopant may include at least one selected from the group consisting of molybdenum (Mo), tungsten (W), and chromium (Cr), preferably molybdenum.

In addition, the carbon material is a single-walled carbon nanotube (SWCNT), a double-walled carbon nanotube (double-walled carbon nanotube, DWCNT), a multi-walled carbon nanotube (Multi-walled carbon nanotube, MWCNT), It may include at least one selected from the group consisting of carbon nanofiber (CNF), graphene oxide (GO) and carbon black, and preferably includes single-walled carbon nanotubes. can do.

In addition, the molar ratio (D/BV, mol/mol) of the dopant (D) to the bismuth vanadate (BV) may be 1 to 20, preferably 5 to 15, more preferably 8 to It can be 12. When the molar ratio of the dopant to the bismuth vanadate is less than 1, the conversion selectivity to hydrogen peroxide through the water oxidation reaction in the photoanode is low, and when it exceeds 20, the molar ratio of the dopant increases. It is not preferable because the effect of generating photocurrent and increasing the amount of hydrogen peroxide is rather reduced.

In addition, the photoanode may further include a substrate, and bismuth vanadate doped with the dopant may be formed on the substrate.

In addition, the cathode may further include carbon paper, and the carbon material and the compound represented by Structural Formula 1 may be formed on the carbon paper.

Bismuth vanadate is known as a photoelectrode material capable of conversion to hydrogen peroxide through a selective two-electron reaction during water oxidation compared to other oxide semiconductor materials. However, the stability for long-term operation is weak due to the low hydrogen peroxide conversion selectivity of bismuth vanadate and the problem of dissolution during the decomposition reaction and reaction of hydrogen peroxide generated on the surface. In the prior art, there is no method for modifying the bismuth vanadate material itself to improve the conversion selectivity, and in order to solve this problem, various oxide semiconductors are deposited on the surface of the electrode using expensive equipment to secure the conversion selectivity. However, even with this technique, the decomposition reaction of hydrogen peroxide cannot be suppressed, and research on the driving stability of the electrode is insufficient.

Therefore, the photoanode of the present invention increases the selectivity for conversion to hydrogen peroxide through the water oxidation reaction by doping bismuth vanadate with a dopant (molybdenum), and then the stability is improved by surface treatment with phosphate. Ultimately, a photoanode excellent for the production of hydrogen peroxide through a photoelectrochemical process was prepared.

The photoanode may react with water to generate hydrogen peroxide, and the cathode may react with oxygen to generate hydrogen peroxide.

The cathode including the carbon material and the compound represented by Structural Formula 1 supported on the carbon material completely suppresses hydrogen production through water decomposition, which is a competitive reaction of the oxygen reduction reaction, and stable hydrogen peroxide production is possible in a wide voltage range.

Finally, the photoelectrochemical cell of the present invention can simultaneously produce hydrogen peroxide even under a condition in which no external voltage is applied through the combination of the photoanode and the cathode.

The present invention comprises the steps of (a) preparing a photoanode comprising bismuth vanadate doped with a dopant; (b) preparing a cathode including a carbon material and a compound represented by Structural Formula 1 supported on the carbon material; and (c) manufacturing a photoelectrochemical cell including the photoanode, the separator, and the cathode.

[Structural Formula 1]

In Structural Formula 1,

R is a hydrogen atom, a carboxyl group, a sulfonic acid group, an amino group, or a hydroxy group.

first, dopant doped bismuth Bana date containing photo anode prepared (step a).

Step a may be performed by dividing it into two steps.

First, a precursor solution including a bismuth precursor, a vanadium precursor, and a dopant precursor is prepared (step a-1).

The bismuth precursor may include at least one selected from the group consisting _{of Bi(NO 3} ) ₃ ·5H ₂ O, BiCl ₃ , BiClO ₅ ·xH ₂ O and BiF _{3 , and preferably Bi(NO 3} ) ₃ · 5H ₂ O may be included.

The vanadium precursor may include at least one selected from the group consisting _{of OV(C 5} H ₇ O ₂ ) ₂ , OV(OCH(CH ₃ ) ₂ ) ₃ , OV(OC ₃ H ₇ ) ₃ and VOCl _{3 and} , preferably OV(C ₅ H ₇ O ₂ ) ₂ .

The dopant precursor may include at least one selected from the group consisting of a molybdenum precursor, a tungsten precursor, and a chromium precursor, and may preferably include a molybdenum precursor.

The molybdenum precursor may include at least one selected from the group consisting of Bis (acetylacetonato) dioxomolybdenum, Molybdenum (VI) oxide and Molybdenum (VI) tetrachloride oxide, and preferably Bis (acetylacetonato) dioxomolybdenum have.

The tungsten precursor may include at least one selected from the group consisting _{of Na 2} WO ₄ ·2H ₂ O, WCl ₆ and H ₂ WO _{4 , and preferably include Na 2} WO ₄ ·2H ₂ O. .

The chromium precursor may include at least one selected from the group consisting _{of Na 2} Cr ₂ O ₇ ·4H ₂ O, CrO ₃ and K ₂ Cr ₂ O _{7 , preferably Na 2} Cr ₂ O ₇ ·4H ₂ It may contain O.

Next, the precursor solution is dried and heat-treated to prepare dopant-doped bismuth vanadate (step a-2).

In addition, the heat treatment of step a-2 may be performed at 300 to 800 °C, preferably at 400 to 700 °C, more preferably at 450 to 600 °C. When the heat treatment is performed at less than 300° C., the crystallinity of bismuth vanadate is low, which is not preferable, and when it exceeds 800° C., additional reactions such as melting of the FTO substrate may occur, which is not preferable.

In addition, after step a-2, the surface treatment of the photoanode with a solution containing a phosphate, drying, and heat treatment (step a-2'); may be further included.

In addition, the heat treatment of step a-2' may be performed at 100 to 500 °C, preferably at 200 to 400 °C, more preferably at 250 to 350 °C. When the heat treatment is performed at less than 100° C., it is not preferable because the process of surface treatment of the photoanode with phosphate is not well performed, so that phosphorus (P) cannot be formed on the bismuth vanadate, and when it exceeds 500° C. It is not preferable because an addition reaction may occur.

Next, the carbon material and the on carbon material supported containing a compound represented by the structural formula 1 cathode prepared (step b).

Step b may be performed by dividing it into two steps.

First, a mixed solution is prepared by mixing the compound represented by Structural Formula 1 and a carbon material (step b-1).

The anthraquinone precursor may include at least one selected from the group consisting of Anthraquinone-2-carboxylic acid, Anthraquinone, Anthraquinone-2-sulfonic acid, 2-Aminoanthraquinone and 2-Hydroxyanthraquinone, preferably Anthraquinone-2-carboxylic acid, at least one selected from the group consisting of Anthraquinone and Anthraquinone-2-sulfonic acid, more preferably Anthraquinone-2-carboxylic acid.

The carbon material is single-walled carbon nanotube (SWCNT), double-walled carbon nanotube (DWCNT), multi-walled carbon nanotube (MWCNT), carbon nano It may include at least one selected from the group consisting of fibers (Carbon nanofiber, CNF), graphene oxide (GO) and carbon black, and preferably include single-walled carbon nanotubes. have.

Next, the mixed solution is dried and heat-treated to prepare a cathode including a carbon material on which the compound represented by Structural Formula 1 is supported (step b-2).

The heat treatment of step b-2 may be performed at 50 to 100°C, preferably at 70 to 90°C. When the heat treatment is performed at less than 50° C., it is not preferable because the compound represented by Structural Formula 1 is not supported on the carbon material, and when it exceeds 100° C., it is not preferable because an addition reaction may occur.

Finally, the above photo anode , separators and cathode containing photoelectrochemical Prepare the cell (step c).

A photoelectrochemical cell may be formed as a three-electrode system by adding a counter electrode to the photoanode and cathode.

A photoelectrochemical cell may be formed in a two-electrode system by directly connecting the photoanode and the cathode. When the photoanode and the cathode are directly connected, hydrogen peroxide may be prepared in the photoanode and the cathode, respectively, even under a condition in which no external voltage is applied.

The separation membrane may include at least one selected from the group consisting of Nafion-based, porous organic-inorganic material, fine polymer material, and graphene, and may preferably include Nafion-based material.

The present invention comprises the steps of (1) providing the photoelectrochemical cell; And (2) the photoanode oxidizes water under light irradiation to produce hydrogen peroxide (H ₂ O ₂ ), and the cathode reduces oxygen to produce hydrogen peroxide; provides a method for producing hydrogen peroxide, including.

In addition, the oxidation and reduction may be performed simultaneously.

In addition, the photoelectrochemical cell may produce hydrogen peroxide with electrical energy generated from solar energy.

[Example]

Hereinafter, a preferred embodiment of the present invention will be described. However, this is for illustrative purposes only, and the scope of the present invention is not limited thereto.

photo anode ( photoanodes )

Example One: Mo (10%)- BVO

After each 0.1M of Bi(NO ₃ ) ₃ ·5H ₂ O and OV(C ₅ H ₇ O ₂ ) ₂ was dissolved in Acetylacetonate, 0.01M of Bis(acetylacetonato)dioxomolybdenum was further added, followed by stirring for 24 hours to obtain a mixed solution. prepared.

70 μL of the mixed solution was dropped on a 1×2 cm ² FTO substrate and spin-coated at 3,000 rpm for 30 seconds, followed by heat treatment at 500° C. for 10 minutes. After repeating the spin coating and heat treatment 10 times, finally heat treatment at 500° C. for 2 hours to prepare a Mo(10%)-BVO photoanode in which 10% (mol%) Mo was added.

Example 2: W- BVO

A W-BVO photoanode was prepared in the same manner as in Example 1 except that 0.01M _{of Na 2} WO ₄ ·2H ₂ O was used instead of using Bis(acetylacetonato)dioxomolybdenum at 0.01M.

Example 3: Cr - BVO

A Cr-BVO photoanode was prepared in the same manner as in Example 1, except that 0.01M _{of Na 2} Cr ₂ O ₇ .4H ₂ O was used instead of 0.01M of Bis(acetylacetonato)dioxomolybdenum.

Example 4: Mo (5%)- BVO

A Mo(5%)-BVO photoanode was prepared in the same manner as in Example 1 except that 0.005M was used instead of 0.01M of Bis(acetylacetonato)dioxomolybdenum.

Example 5: Mo (15%)- BVO

A Mo(15%)-BVO photoanode was prepared in the same manner as in Example 1 except that 0.015M of Bis(acetylacetonato)dioxomolybdenum was used instead of 0.01M.

Example 6: P- Mo - BVO

Na ₃ PO ₄ 10mM was added to a 9:1 (vol%) mixed solution of ethanol and water to prepare a mixed solution. 20 μL of the mixed solution ^{was dropped on the 1×2 cm 2} Mo (10%)-BVO photoanode prepared according to Example 1 and heat-treated at 300° C. for 30 minutes to form a P-Mo-BVO photo anode having a phosphoric acid group bonded to the surface Nodes were fabricated.

comparative example One: BVO

A BVO photoanode was prepared in the same manner as in Example 1, except that Bis(acetylacetonato)dioxomolybdenum was not used instead of 0.01M.

cathode (cathode)

Example 7: AQ- CNT /C

Anthraquinone-2-carboxylic acid 3 mM, 6.3 mg of single-walled carbon nanotubes (SWCNT) and 12 μL of a 5 wt% Nafion solution were ultrasonically dispersed in 1 mL of acetonitrile to prepare a mixed solution.

The mixed solution was dropped on 1×2 cm ² carbon paper and heat-treated at 80° C. for 10 minutes. The coating and heat treatment processes were repeated 10 times to prepare an AQ-CNT/C cathode in which anthraquinone (AQ) was supported on carbon nanotubes.

comparative example 2: CNT /C

Anthraquinone-2-carboxylic acid CNT / C cathode was prepared in the same manner as in Example 7 except that it was not used instead of using 3 mM.

comparative example 3: C

1×2cm ^{2 A} C cathode was prepared using carbon paper.

photoelectrochemical cell( photoelectrochemical ( PEC ) cell)

device example One: Mo - BVO │AQ- CNT /C

A two-electrode system was implemented with a cell containing 1M NaHCO ₃ ( _{pH ~7.8 adjusted by HClO 4} ) and separated by a Nafion membrane (Membrane Nafion N117).

After placing the Mo(10%)-BVO photoanode prepared according to Example 1 and the AQ-CNT/C cathode prepared according to Example 7 in each cell in the cell, the solution with the photoanode was Ar (99.9%) gas, the solution with the cathode was purged with O ₂ (99.9%) gas for at least 15 minutes. By combining the photoanode and the cathode, a Mo-BVO|AQ-CNT/C photoelectrochemical cell was prepared.

device example 2: P- Mo - BVO │AQ- CNT /C

In the same manner as in Device Example 1, except that the P-Mo-BVO photoanode prepared according to Example 6 was used instead of using the Mo(10%)-BVO photoanode prepared according to Example 1 A P-Mo-BVO|AQ-CNT/C photoelectrochemical cell was prepared.

Device comparison example One: Mo - BVO ? CNT /C

Mo-BVO | CNT/C photoelectricity in the same manner as in Device Example 1, except that the CNT/C cathode prepared according to Comparative Example 2 was used instead of using the AQ-CNT/C cathode prepared according to Example 7 A chemical cell was prepared.

Device comparison example 2: Mo - BVO │C

A Mo-BVO│C photoelectrochemical cell was prepared in the same manner as in Device Example 1, except that the C cathode prepared according to Comparative Example 3 was used instead of the AQ-CNT/C cathode prepared according to Example 7 did.

[Test Example]

test example One: photo anode and cathodic surface properties

FIG. 2a shows an SEM photograph of the photoanode manufactured according to Example 1, and FIG. 2b shows XRD patterns of the photoanode manufactured according to Examples 1 to 3 and Comparative Example 1. Referring to FIG. 2c shows XPS spectra of O 1s for the photoanodes prepared according to Examples 1 to 3 and Comparative Example 1, and FIG. 2d is an anthraquinone-carbon nanotube (AQ-CNT), carbon nanotube (CNT). ) and FTIR spectra of anthraquinone (Pure AQ) samples.

_{Referring to FIG. 2A , it can be seen that the bismuth vanadate (BiVO 4} ) photoanode doped with molybdenum (Mo) has a porous structure having an average particle size of 60 to 70 nm.

Referring to FIG. 2B , in the case of Comparative Example 1, which is pure bismuth vanadate (BVO), two main peaks are shown at 34 to 36 degrees. This shows that bismuth vanadate (BiVO ₄ ) has a monoclinic structure. However, in the case of Examples 1 to 3 including the dopant, the two main picks are combined into one. This shows that the dopant-doped bismuth vanadate has a tetragonal structure.

Referring to FIG. 2C , it can be seen that when bismuth vanadate is doped with dopants (Mo, W, Cr), the binding energy of oxygen increases and the surface hydroxyl group of oxygen also increases.

Referring to FIG. 2D , chemical structures of single-walled carbon nanotubes (SWCNTs), anthraquinone-single-walled carbon nanotubes (AQ-SWCNTs), and pure anthraquinones (pure AQ) can be confirmed. Since the anthraquinone-single-walled carbon nanotube (AQ-SWCNT) has a chemical structure similar to that of pure anthraquinone (pure AQ), it can be confirmed that the anthraquinone is anchored to the single-walled carbon nanotube.

test example 2: photoanode's photoelectrochemical activation

test example 2-1: photoanode's Photocurrent generation and hydrogen peroxide production efficiency

Figure 3a shows the photoelectrochemical properties (photocurrent generation, LSVs) and the hydrogen peroxide production efficiency by voltage ([H ₂ O ₂ ] _A ) of the photoanodes prepared according to Examples 1, 5, 6 and Comparative Example 1; 3B shows the photoelectrochemical properties (photocurrent generation, LSVs) and the hydrogen peroxide production efficiency ([H ₂ O ₂ ] _A ) of the photoanodes manufactured according to Examples 1 to 3 and Comparative Example 1 by voltage. 3c is a Mott-Schottky (MS) graph of the photoanodes manufactured according to Examples 1 to 3 and Comparative Example 1 measured at a fixed frequency of 1 kHz, and FIG. 3d is Examples 1 to 3 and Comparative Example 1 The Nyquist plots are shown under AM 1.5G irradiation (100 mW·cm ^-2 ), 1M NaHCO ₃ solution (pH ~7.8), and 1.0V _RHE applied potential of the photoanode prepared according to .

Referring to FIG. 3A , it can be seen that bismuth vanadate (Example 1) doped with 10% (mol%) molybdenum shows the highest photocurrent production and hydrogen peroxide production amount.

Referring to FIG. 3B , it was found that bismuth vanadate doped with molybdenum showed higher photocurrent production and hydrogen peroxide production compared to bismuth vanadate doped with no dopant or doped with tungsten (W) and chromium (Cr). can be checked

Referring to FIGS. 3C and 3D , the electrical conductivity and interfacial resistance characteristics of bismuth vanadate according to the dopant type can be identified. It can be seen that the bismuth vanadate doped with a dopant has improved both electrical conductivity and interfacial resistance, and among them, it can be seen that the bismuth vanadate doped with molybdenum shows the best efficiency.

test example 2-2: photoanode's Hydrogen peroxide decomposition amount

4A shows the amount of hydrogen peroxide decomposition with time of the photoanodes prepared according to Examples 1 to 3 and Comparative Example 1, and FIG. 4B is the photoanode prepared according to Examples 1 to 3 and Comparative Example 1. The photocurrent flow and the amount of generated electric charge during the measurement of the amount of hydrogen peroxide decomposition with time are shown. FIG. 4c shows a value obtained by dividing the amount of hydrogen peroxide decomposition with time of the photoanodes manufactured according to Examples 1 to 3 and Comparative Example 1 by the amount of generated electric charge.

Referring to FIG. 4A , it can be seen that the amount of decomposition of hydrogen peroxide is reduced in the case of dopant-doped bismuth vanadate compared to pure bismuth vanadate (BVO, Comparative Example 1).

Referring to FIG. 4B , it can be seen that bismuth vanadate doped with the remaining dopants (Mo, W) except for chromium (Cr) exhibits improved photocurrent production.

Referring to FIG. 4C , it can be seen that the amount of decomposed hydrogen peroxide is the smallest compared to the photocurrent generated by bismuth vanadate doped with molybdenum (Mo).

test example 3: cathodic photoelectrochemical activation

_{Figure 5a shows Cyclic voltammograms (CVs) in the argon (Ar) and oxygen (O 2} ) gas phase of the cathode prepared according to Example 7, Comparative Example 2 and Comparative Example 3, Figure 5b is Example 7, Comparative Example 2 and Comparative Example 3 of the cathode prepared according to argon (Ar) and oxygen (O ₂ ) gas, in the dark state, 1M NaHCO ₃ solution (pH ~7.8) and -1.5V _{RHE at the} applied potential Nyquist plots are shown. Figure 5c shows Koutecky-Levich plots of anthraquinone-carbon nanotube (AQ-CNT) and carbon nanotube (CNT) powder. The Koutecky-Levich plots are a rotating disk electrode (RDE) measurement when _{-0.5V Ag / AgCl} applied voltage is applied to a 0.1M KOH solution pre-purged _{with oxygen (O 2 ) gas.} obtained.

Referring to Figure 5a, carbon paper cathode (C, Comparative Example 3), carbon nanotube cathode (CNT / C, Comparative Example 2) and anthraquinone AQ-CNT / C cathode supported on carbon nanotube (Example) 7) of argon (Ar) and oxygen (O ₂ ) can be confirmed in the gas phase electrochemical properties. It can be seen that the AQ-CNT/C cathode in which anthraquinone is supported on carbon nanotubes shows reduction and oxidation peaks of anthraquinone in argon gas and improved reduction current in oxygen gas.

Referring to FIG. 5b, carbon paper cathode (C, Comparative Example 3), carbon nanotube cathode (CNT/C, Comparative Example 2) and anthraquinone supported on carbon nanotube AQ-CNT/C cathode (Example) The interfacial resistance characteristics can be confirmed in the argon (Ar) and oxygen (O _{2 ) gases of 7).} All electrodes exhibited lower interfacial resistance in oxygen gas than argon gas, and it can be seen that the AQ-CNT/C cathode in which anthraquinone is supported on carbon nanotubes exhibits the lowest interfacial resistance in oxygen gas.

Referring to FIG. 5c, the oxygen reduction reaction rate characteristics of the carbon nanotube cathode (CNT/C, Comparative Example 2) and the AQ-CNT/C cathode (Example 7) in which anthraquinone is supported on the carbon nanotube can be confirmed. have. It can be seen that the carbon nanotube cathode (Comparative Example 2) and the AQ-CNT/C cathode (Example 7) in which anthraquinone is supported on the carbon nanotube show oxygen reduction reaction rates of 4 and 2, respectively. This shows the reduction selectivity to hydrogen peroxide due to the anthraquinone.

test example 4: photoelectrochemical cell's photoelectrochemical activation

Figure 6a shows the photoelectrochemical characteristics (photocurrent generation, LSVs) and the hydrogen peroxide or oxygen generation efficiency for each voltage of the photoelectrochemical cell prepared according to Device Example 1, and Figure 6b shows Device Example 1 and Device Comparative Example 1. It shows the production and efficiency of hydrogen peroxide or hydrogen for each voltage of the manufactured photoelectrochemical cell.

Referring to FIG. 6a , it can be confirmed that hydrogen peroxide is simultaneously generated at the photoanode through _{FE A} (H ₂ O ₂ ), FE _A (O ₂ ) and FE _A (H ₂ O ₂ +O _{2 ).} can In addition, it can be confirmed that the cathode exhibits 100% hydrogen peroxide production efficiency in all voltage ranges through _{FE C} (H ₂ O _{2 ).}

Referring to FIG. 6b , in Device Comparative Example 1 using a carbon nanotube cathode (CNT/C), it can be confirmed that hydrogen is competitively generated in all voltage ranges. In contrast, it can be seen that Device Example 1 using the AQ-CNT/C cathode in which anthraquinone is supported on carbon nanotubes shows 100% hydrogen peroxide conversion selectivity in all voltage ranges.

test example 5: surface treated with phosphate photoanode's with or without photoelectrochemical cell's photoelectrochemical activation

test example 5-1: surface-treated with phosphate photo anode used photoelectrochemical Cell photocurrent generation and hydrogen peroxide production efficiency

7A shows the photoelectrochemical characteristics (photocurrent generation, LSVs) and the hydrogen peroxide production efficiency for each voltage of the photoelectrochemical cells prepared according to Device Examples 1 and 2, and FIG. 7B shows Device Examples 1 and 2 and Device Comparative Example 1 The photocurrent generation amount and hydrogen peroxide production amount according to the time of the photoelectrochemical cell prepared according to FIG. 7c shows the photoelectrochemical properties of the photoelectrochemical cells prepared according to Device Examples 1 and 2 for 100 hours, and FIG. 7d shows the surface SEM image of the photoanode used in Device Example 1 after 100 hours of reaction. will be. 7e shows Bi 4f and V 2p XPS spectra before and after 100 hours of reaction of the photoanode used in Device Examples 1 and 2, and FIG. 7f is 100 hours of the photoanode used in Device Examples 1 and 2 P 2p and Sn 3d XPS spectra before and after the reaction are shown.

Specifically, the photoelectrochemical properties and the amount of hydrogen peroxide production were measured with a three-electrode system using a Pt electrode sputtered on an FTO substrate (20 mA for 30 sec; Cressington 208HR) as a counter electrode.

Referring to FIG. 7a , it can be seen that Device Example 2 (P-Mo-BVO|AQ-CNT/C) using a photoanode surface-treated with phosphate exhibits improved photocurrent generation and conversion selectivity to hydrogen peroxide.

Referring to FIG. 7B , it can be seen that the photoelectrochemical cell (P-Mo-BVO | AQ-CNT/C) manufactured according to Device Example 2 shows stable photocurrent generation and high hydrogen peroxide production.

Referring to FIG. 7c , through comparison of photocurrent generation for 100 hours, when a photoanode surface-treated with phosphate is used, stable photocurrent is generated, but when a phosphate group is not bound, it can be confirmed that the initial photocurrent almost disappears within 20 hours. .

Referring to FIG. 7D , when the photoanode surface-treated with phosphate is not used, it can be seen that the existing structure of the bismuth vanadate deposited on the substrate collapses and the FTO is exposed after photoelectrochemical reaction for 100 hours.

7e and 7f, when the photoanode surface-treated with phosphate is not used, the peaks of bismuth (Bi) and vanadate (V) are reduced, and the tin (Sn) peak of FTO is increased. increase can be seen.

test example 5-2: surface-treated with phosphate with photo anode cathode Photocurrent generation and hydrogen peroxide generation when directly connected

8A shows the photoelectrochemical properties (photocurrent generation, LSVs) of Examples 1, 6, 7, and Comparative Examples 2 and 3, and FIG. 8B shows Device Examples 1, 2, and Comparative Example in the absence of external voltage. The photoelectrochemical properties (photocurrent generation, LSVs) of 1 and 2 are shown. 8C shows the amount of photocurrent generated and the amount of hydrogen peroxide generated according to time in Device Examples 1 and 2 in the absence of an externally applied voltage.

Specifically, a two-electrode system was formed by directly connecting a photoanode and a cathode to achieve the condition in which there is no externally applied voltage.

Referring to FIG. 8A , it can be predicted whether the photoelectrochemical cell can be driven without an externally applied voltage based on the junction of the oxidation current of the photoanode and the reduction current of the cathode.

Referring to FIG. 8b, a photoanode (P-Mo-BVO) in which phosphorus (P) is formed on bismuth vanadate by surface treatment with a phosphate salt (P-Mo-BVO) and a cathode in which anthraquinone is supported on carbon nanotubes (AQ-CNT/C) It can be seen that the photoelectrochemical cell (Device Example 2) using ) showed the highest photocurrent production.

Referring to FIG. 8C , it can be seen that when phosphorus (P) is formed on the bismuth vanadate by surface-treating the molybdenum-doped bismuth vanadate with a phosphate, stable photocurrent generation and improved hydrogen peroxide production are exhibited.

The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

Claims (20)

a photoanode comprising bismuth vanadate (BiVO _{4 ) doped with a dopant;} and
Including; a cathode comprising a carbon material and a compound represented by Structural Formula 1 supported on the carbon material;
Wherein the photoanode is surface-treated with phosphate, a photoelectrochemical (PEC) cell:
[Structural Formula 1]

In Structural Formula 1,
R is a hydrogen atom, a carboxyl group, a sulfonic acid group, an amino group, or a hydroxy group. delete According to claim 1,
The photoelectrochemical cell, characterized in that by surface-treating the dopant-doped bismuth vanadate with the phosphate, the photoanode forms phosphorus (P) on the dopant-doped bismuth vanadate. . According to claim 1,
The photoelectrochemical cell, characterized in that the dopant comprises at least one selected from the group consisting of molybdenum (Mo), tungsten (W) and chromium (Cr). According to claim 1,
The carbon material is single-walled carbon nanotube (SWCNT), double-walled carbon nanotube (DWCNT), multi-walled carbon nanotube (MWCNT), carbon nano A photoelectrochemical cell comprising at least one selected from the group consisting of fibers (Carbon nanofiber, CNF), graphene oxide (GO), and carbon black. According to claim 1,
The photoelectrochemical cell, characterized in that the molar ratio (D/BV, mol/mol) of the dopant (D) to the bismuth vanadate (BV) is 1 to 20. According to claim 1,
The photoanode further comprises a substrate,
The photoelectrochemical cell, characterized in that the dopant-doped bismuth vanadate is formed on the substrate. According to claim 1,
The cathode further comprises carbon paper,
The photoelectrochemical cell, characterized in that the carbon material and the compound represented by Structural Formula 1 are formed on the carbon paper. (a) preparing a photoanode comprising bismuth vanadate doped with a dopant;
(b) preparing a cathode including a carbon material and a compound represented by Structural Formula 1 supported on the carbon material; and
(c) preparing a photoelectrochemical cell including a separator, the photoanode and the cathode;
Wherein the photoanode is surface-treated with phosphate, a method of manufacturing a photoelectrochemical cell:
[Structural Formula 1]

In Structural Formula 1,
R is a hydrogen atom, a carboxyl group, a sulfonic acid group, an amino group, or a hydroxy group. 10. The method of claim 9,
The step (a) is
(a-1) preparing a precursor solution including a bismuth precursor, a vanadium precursor, and a dopant precursor; and
(a-2) drying the precursor solution and heat-treating to prepare dopant-doped bismuth vanadate; 11. The method of claim 10,
The method of manufacturing a photoelectrochemical cell, characterized in that the heat treatment of step (a-2) is performed at 300 to 800 ℃. 11. The method of claim 10,
After the step (a-2), the method for manufacturing the photoelectrochemical cell is
(a-2') surface-treating the photoanode with a solution containing a phosphate, drying, and heat-treating; 13. The method of claim 12,
The method of manufacturing a photoelectrochemical cell, characterized in that the heat treatment of step (a-2') is performed at 100 to 500 ℃. 11. The method of claim 10,
The bismuth precursor includes at least one selected from the group consisting of Bi(NO ₃ ) ₃ ·5H ₂ O, BiCl ₃ , BiClO ₅ ·xH ₂ O and BiF _{3 ,}
The vanadium precursor comprises at least one selected from the group consisting of OV(C ₅ H ₇ O ₂ ) ₂ , OV(OCH(CH ₃ ) ₂ ) ₃ , OV(OC ₃ H ₇ ) ₃ and VOCl _{3 .} A method for manufacturing a photoelectrochemical cell. 11. The method of claim 10,
The method of manufacturing a photoelectrochemical cell, characterized in that the dopant precursor comprises at least one selected from the group consisting of a molybdenum precursor, a tungsten precursor, and a chromium precursor. 10. The method of claim 9,
The step (b) is
(b-1) preparing a mixed solution by mixing the compound represented by Structural Formula 1 and a carbon material; and
(b-2) drying and heat-treating the mixed solution to prepare a cathode including a carbon material on which the compound represented by Structural Formula 1 is supported; 17. The method of claim 16,
The method of manufacturing a photoelectrochemical cell, characterized in that the heat treatment of step (b-2) is performed at 50 to 100 ℃. (1) providing the photoelectrochemical cell of claim 1; and
(2) the photoanode oxidizes water under light irradiation to produce hydrogen peroxide (H ₂ O ₂ ), and the cathode reduces oxygen to produce hydrogen peroxide;
A method for producing hydrogen peroxide comprising. 19. The method of claim 18,
Method for producing hydrogen peroxide, characterized in that the oxidation and reduction are performed simultaneously. 19. The method of claim 18,
Method for producing hydrogen peroxide, characterized in that the photoelectrochemical cell produces hydrogen peroxide with electric energy generated from solar energy.

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