KR20240163456A - Bipolar electrode-based galvanic cell, sensor for detecting hydrogen peroxide and screening device for oxygen reduction catalyst - Google Patents

Abstract

A bipolar electrode-based galvanic cell in which a redox reaction spontaneously proceeds without a driving electrode is provided. According to one aspect of the present invention, a bipolar electrode-based galvanic cell is provided, comprising: a substrate; a bipolar electrode disposed on the substrate and including a first end part and a second end opposite to the first end; and a cover part covering between the first end part and the second end part; wherein the cover part includes a first opening through which the first end part is exposed and a second opening through which the second end part is exposed, and the first end part and the second end part are modified with catalyst particles which are the same as or different from each other.

Description

{BIPOLAR ELECTRODE-BASED GALVANIC CELL, SENSOR FOR DETECTING HYDROGEN PEROXIDE AND SCREENING DEVICE FOR OXYGEN REDUCTION CATALYST}

The present invention relates to a bipolar electrode-based galvanic cell, and more particularly, to a bipolar electrode-based galvanic cell, a hydrogen peroxide sensor, and a screening device for a catalyst for oxygen reduction reaction.

Bipolar electrodes function as electrodes without external conductor connections, and thus have high value for use as a mass/various sample sensing system by easily integrating multiple bipolar electrodes into an array form. However, since bipolar electrodes function as electrodes without external conductor connections, direct current measurement has been difficult.

Indium tin oxide (ITO), an example of a material that forms a bipolar electrode, is widely used as a transparent electrode material because it has both high electrical conductivity and optical transparency. For example, indium tin oxide is used for conductive coating purposes in the fields of liquid crystal displays, flat panel displays, plasma displays, touch screens, electronic paper, organic light-emitting diodes, solar cells, antistatic coatings, and electromagnetic interference shields. In addition, indium tin oxide is used as a material for various optical coatings, infrared reflective coatings that are most notable in buildings and automobiles, and its uses are expanding as it is used in gas sensors, antireflection coatings, and magnifying reflectors in Vertical-cavity surface-emitting lasers (VCSELs).

However, electrochemical systems based on general bipolar electrodes may require a potential difference between the two ends of the bipolar electrode for Faradaic reactions through a driving electrode that applies voltage from the outside. In order to implement this, there was a problem in that an additional connector that could be connected to an electrical outlet was required.

The purpose of the present invention is to provide a bipolar electrode-based galvanic cell capable of carrying out a spontaneous oxidation-reduction reaction without a driving electrode that applies voltage.

Another object of the present invention is to provide a bipolar electrode-based galvanic cell in which the amount of faradaic current resulting from a spontaneous redox reaction can be optically read via fluorescence or colorimetric measurements.

Another object of the present invention is to provide a hydrogen peroxide sensor capable of optically detecting hydrogen peroxide.

Another object of the present invention is to provide a screening device for a catalyst for oxygen reduction reaction.

The purposes of the present invention are not limited to the purposes mentioned above, and other purposes and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. In addition, it will be easily understood that the purposes and advantages of the present invention can be realized by the means and combinations thereof indicated in the claims.

According to a first aspect of the present invention for achieving the above object, a bipolar electrode-based galvanic cell is provided, comprising: a substrate; a bipolar electrode disposed on the substrate and including a first end part and a second end opposite the first end; and a cover part covering between the first end part and the second end; wherein the cover part includes a first opening through which the first end part is exposed and a second opening through which the second end part is exposed, and the first and second ends are modified with catalyst particles that are the same as or different from each other.

According to the second aspect of the present invention, in the first aspect, the first end may be an oxidation electrode, and the second end may be a reduction electrode.

According to a third aspect of the present invention, the first or second aspect may include a first nanoparticle modifying the first end and a second nanoparticle modifying the second end.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the first and second nanoparticles may each independently be a single metal, an alloy multi-metal, a nanoparticle encapsulated with a dendrimer, or a nanoparticle having a core-shell structure.

According to a fifth aspect of the present invention, in the fourth aspect, the single metal includes one selected from the group consisting of Pt, Au, Pd, Ni, Fe, and Cu, and the alloy multi-metal and the core-shell structured nanoparticles may each independently include two or more selected from the group consisting of Pt, Au, Pd, Ni, Fe, and Cu.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the first opening may include a color indicator material therein, and the second opening may include a target material therein.

According to the seventh aspect of the present invention, in the sixth aspect, the color indicator material may include at least one of a chromogenic material and a fluorescent material.

According to the eighth aspect of the present invention, in the sixth aspect, the target material may include an oxygen solution or a hydrogen peroxide solution.

According to a ninth aspect of the present invention, a bipolar electrode-based galvanic cell can be provided, further comprising a salt bridge in any one of the first to eighth aspects.

According to a tenth aspect of the present invention, a hydrogen peroxide sensor can be provided, comprising a bipolar electrode-based galvanic cell according to any one of the first to ninth aspects.

According to an eleventh aspect of the present invention, a screening device for a catalyst for oxygen reduction reaction can be provided, comprising a galvanic cell based on a bipolar electrode according to any one of the first to ninth aspects.

The above-mentioned solution to the problem does not enumerate all the features of the present invention. The various features of the present invention and the advantages and effects thereof can be understood in more detail by referring to the specific examples below.

According to one aspect of the present invention, a bipolar electrode-based galvanic cell capable of carrying out a spontaneous oxidation-reduction reaction without a driving electrode applying voltage can be provided.

According to another aspect of the present invention, a bipolar electrode-based galvanic cell can be provided in which the amount of faradaic current resulting from a spontaneous redox reaction can be optically read via fluorescence or colorimetric measurements.

According to another aspect of the present invention, a hydrogen peroxide sensor capable of optically detecting hydrogen peroxide or a screening device for a catalyst for oxygen reduction reaction can be provided.

In addition to the effects described above, the specific effects of the present invention are described below together with the specific contents for carrying out the invention.

Figure 1 is a bipolar electrode-based galvanic cell according to one embodiment of the present invention.
FIG. 2 is a schematic diagram of a hydrogen peroxide sensor including a bipolar electrode-based galvanic cell according to one embodiment of the present invention.
Figure 3 is an optical image of a specimen (i) in which the first end and the second end of the hydrogen peroxide sensor of Example 2-2 are modified with Synthesis Example 1-1 (Pt ₂₀₀ ), a control specimen (ii) in which the second end is modified with Synthesis Example 2 (Au ₂₀₀ ) unlike the specimen (i), and a control specimen (iii) in which the second opening is not filled with a hydrogen peroxide solution unlike the specimen (i).
Figure 4 is a fluorescence (x10 ³ au) spectrum that changes as the concentration of hydrogen peroxide in the hydrogen peroxide sensor of Example 2-2 is adjusted from 50 to 2,000 μM.
Figure 5 (a) is a reaction scheme for the oxidation of 4-chloro-1-naphthol (4-CN) to benzo-4-chlorohexadienone (4-CD) in the presence of Pt nanoparticles, Figure 5 (b) is a UV-vis absorption spectrum result of the hydrogen peroxide sensor of Example 2-1, and Figure 5 (c) is a colorimetric intensity profile of the hydrogen peroxide sensor of Example 2-1 according to the concentration of hydrogen peroxide.
FIG. 6 (a) is a schematic diagram showing the oxidation-reduction reaction of the hydrogen peroxide sensor of Example 2-2, FIG. 6 (b) is a cyclic voltammetry result (cyclic voltammogram) of a three-electrode system including the hydrogen peroxide sensor (ii, iv) of Example 2-2, and FIG. 6 (c) is a cyclic voltammetry result applied to (i) a three-electrode system specimen including an ITO electrode as a working electrode and (ii) a three-electrode system specimen including a Pt/ITO electrode, with 100 mM KNO ₃ containing ^{1 mM} [Fe(CN) ₆ ] 3-.
FIG. 7(a) is a schematic diagram showing a spontaneous oxidation-reduction reaction of a screening device for an oxygen reduction reaction catalyst of Example 3-2, FIG. 7(b) is the cyclic voltammetry results of a three-electrode system of a screening device (ii) for an oxygen reduction reaction catalyst of Example 3-2 and control groups (i) and (iii) specimens, and FIG. 7(c) is an optical image of a screening device (i) for an oxygen reduction reaction catalyst of Example 3-2 after 1 minute of reaction time by filling the second opening with 100 mM acetate buffer (pH=4.0) saturated with oxygen, and a control group (ii) which, unlike device (i), has its second opening filled with 100 mM acetate buffer (pH=4.0) saturated with nitrogen.
Fig. 8 (a) is a schematic diagram of a galvanic cell based on a bipolar electrode of Example 3 in which a circular first end is modified with Synthesis Example 1-1 (Pt ₂₀₀ ), and a fan-shaped second end is modified with Synthesis Example 1-2 (Pt ₃₅₀ ), Synthesis Example 1-3 (Pt ₅₅₀ ), Synthesis Example 1-4 (Pt ₁₃₂₀ ), Synthesis Example 2 (Au ₂₀₀ ), and Comparative Synthesis Example 1 (Pt/C), respectively, Fig. 8 (b) is an optical microscope photograph of the first end (Anode) of Fig. 8 (a), Fig. 8 (c) shows the fluorescence intensity of each of the white circle (i~v) regions over time (s) in Fig. 8 (b), and Fig. 8 (d) is a 3D confocal image of the first end region at 3.8 seconds. This is a fluorescence image (3D confocal fluorescence image), and Fig. 8 (e) is an image in which the upper image, which is a fluorescence image, and the lower image, which is an optical image, are combined during the experiment of Fig. 8 (a) to (d).

In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

The numerical range indicated by the term "to" in this specification refers to a numerical range that includes the values described before and after the term as the lower limit and the upper limit, respectively. When multiple numerical values are disclosed as the upper and lower limits of an arbitrary numerical range, the numerical range disclosed in this specification can be understood as an arbitrary numerical range that uses any one of the multiple lower limit values and any one of the multiple upper limit values as the lower limit and the upper limit, respectively.

According to one aspect of the present invention, a bipolar electrode-based galvanic cell is provided, comprising: a substrate; a bipolar electrode disposed on the substrate and including a first end part and a second end opposite the first end; and a cover part covering between the first end part and the second end; wherein the cover part includes a first opening through which the first end part is exposed and a second opening through which the second end part is exposed, and the first end part and the second end are modified with catalyst particles which are the same as or different from each other. Meanwhile, a general bipolar electrode-based electrochemical system requires a potential difference for Faradaic reactions at both ends of the bipolar electrode through a driving electrode which applies voltage from the outside. In order to implement this, there was a problem that a connecting terminal that can be connected to an electrical outlet was required. According to one aspect of the present invention, by modifying the first end and the second end with the same or different catalyst particles so that a spontaneous electrochemical reaction can occur, the first end of the bipolar electrode can be induced to perform the role of an oxidation electrode where an oxidation reaction occurs, and the second end can be induced to perform the role of a reduction electrode where a reduction reaction occurs. Accordingly, a bipolar electrode-based galvanic cell can be implemented, which can perform a spontaneous oxidation-reduction reaction without a driving electrode that applies voltage, and can optically read the amount of faradaic current due to the spontaneous oxidation-reduction reaction through fluorescence and colorimetric measurements. More specifically, when the first end where the oxidation reaction occurs is modified with catalyst particles, the potential at which the oxidation reaction occurs can be increased in the negative direction, and when the second end where the reduction reaction occurs is modified with catalyst particles, the potential at which the reduction reaction occurs can be increased in the positive direction. As a result, the cell potential (△E=E _cathode -E _anode ) due to the potential difference between the first end, which is the oxidation electrode, and the second end, which is the reduction electrode, becomes higher than 0, so that a spontaneous oxidation-reduction reaction can occur.

Below, the configuration of the present invention will be described in more detail with reference to the drawings.

1. Galvanic cell based on bipolar electrodes

Figure 1 is a bipolar electrode-based galvanic cell according to one embodiment of the present invention.

Referring to FIG. 1, a bipolar electrode-based galvanic cell (100) according to the present invention may include a substrate (10), a bipolar electrode (20), a cover part (30), and a salt bridge (40).

The substrate (10) according to the present invention can support the entire detailed components of a bipolar electrode-based galvanic cell.

The substrate (10) according to the present invention may be any one selected from the group consisting of a glass substrate, a plastic substrate, and a flexible substrate. However, although the technical idea of the present invention is not limited to the material or shape of the substrate, a transparent substrate with smooth light transmission may be preferable when considering the usability of the electrode.

The bipolar electrode (20) according to the present invention can serve as a passage through which electrons from the oxidation electrode move to the reduction electrode.

Specifically, the bipolar electrode (20) may include a first end (20e1), a second end (20e2) opposite to the first end (20e1), and a central portion (20c) disposed between the first end (20e1) and the second end (20e2). According to one embodiment of the present invention, a galvanic cell in which a spontaneous oxidation-reduction reaction can occur can be implemented by modifying the first and second ends with the same or different catalyst particles.

According to one embodiment of the present invention, the ratio of the areas occupied by the first end (20e1), the second end (20e2), and the central portion (20c) based on the upper surface of the bipolar electrode (20) (area of the first end: area of the central portion: area of the second end) may be 1:0.4:1 to 1:20:1, and specifically, 1:1.7:1 to 1:20:1.

The bipolar electrode (20) according to the present invention may include any one selected from the group consisting of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), carbon nanotubes (CNT), carbon paste, pyrolytic carbon, and combinations thereof. However, the technical idea of the present invention is not limited thereto, and any electrode that exhibits electrical conductivity without being connected to an external conductor may be applied.

The first end (20e1) and the second end (20e2) according to the present invention may be modified with the same or different catalyst particles. Specifically, the first end (20e1) may be modified with the first nanoparticle, and the second end (20e2) may be modified with the second nanoparticle. According to one embodiment of the present invention, the first end (20e1) is modified with the first nanoparticle, and the second end (20e2) is modified with the second nanoparticle, so that the cell potential (△E = E _cathode -E _anode ) becomes higher than 0, so that an oxidation-reduction reaction can occur spontaneously. Here, the first end (20e1) may be an oxidation electrode (anode) and the second end (20e2) may be a reduction electrode (cathode). In this case, any catalyst particle that can induce a spontaneous oxidation-reduction reaction by making the cell potential (△E=E _cathode -E _anode ) higher than 0 due to the potential difference between the first end, which is the oxidation electrode, and the second end, which is the reduction electrode, is not particularly limited and can be selected in various ways.

For example, the first and second nanoparticles may each independently be a single metal, an alloy multimetal, a dendrimer-encapsulated nanoparticle (DENs) or a core-shell structured nanoparticle. In one example, the single metal may include any one selected from the group consisting of Pt, Au, Pd, Ni, Fe and Cu. In another example, the alloy multimetal and the core-shell structured nanoparticles may each independently include two or more selected from the group consisting of Pt, Au, Pd, Ni, Fe and Cu. In yet another example, the encapsulated nanoparticles in the dendrimer-encapsulated nanoparticles may include the single metal, alloy multimetal or core-shell structured nanoparticles described above.

For example, in the dendrimer-encapsulated nanoparticles, the dendrimer may be polyamidoamine (PAMAM).

Specifically, in the dendrimer-encapsulated nanoparticle, the terminal functional group of the dendrimer may be an amine group, and the amine group may chemically bond with the surface of the bipolar electrode. That is, the dendrimer-encapsulated nanoparticle may chemically bond with both the first end and the second end by cyclic voltammetry. For example, in order to induce chemical bonding between the dendrimer-encapsulated nanoparticle and the bipolar electrode, a voltage may be applied to the bipolar electrode by cyclic voltammetry between an initial voltage of 1.20 V and 1.75 V (vs Ag/AgCl) three times. At this time, the number of voltage cycles may be 2 or 3 cycles, and the scan speed may be 5 to 10 mV/s. However, in some cases, the initial voltage (1.2 V) may vary in the negative direction (approximately ~0.1 V) to an extent that no additional reduction reaction occurs, and 1.75 V may also vary in the positive direction (approximately ~1.9 V) to an extent that no degradation of the ITO electrode occurs. If the range of the above-mentioned scanning speed is less than the above-mentioned numerical range, the fixation time of the dendrimer-encapsulated nanoparticles may increase, which may be inefficient, and if it exceeds the above-mentioned numerical range, the fixation efficiency may decrease. If a method of immersing the bipolar electrode in a solution of dendrimer-encapsulated nanoparticles without applying voltage by cyclic voltammetry is used, the first and second ends may not be sufficiently modified or functionalized.

The central portion (20c) according to the present invention may not be modified with catalyst particles. According to one embodiment of the present invention, by modifying the first end (20e1) and the second end (20e2) and not modifying the central portion (20c), the oxidation-reduction reaction can proceed physically and electrochemically separated in a bipolar electrode-based galvanic cell.

The cover part (30) according to the present invention can act as a separator that prevents the material filled in the first opening and the material filled in the second opening from mixing with each other.

The cover part (30) according to the present invention covers the space between the first end (20e1) and the second end (20e2). Specifically, since the cover part (30) covers the space between the first end (20e1) and the second end (20e2), the material filled in the first opening and the material filled in the second opening may not be mixed with each other.

For example, the cover part (30) may be appropriately selected from materials having excellent adhesion to the substrate. According to one example, when the substrate is a glass substrate, the cover part may include PDMS (polydimethylsiloxane).

According to one embodiment of the present invention, a 3D printer device can be used to manufacture the cover part (30). For example, the cover part (30) can be manufactured by pouring liquid PDMS resin into a mold corresponding to the shape of the cover part (30) using a 3D printer device.

The cover part (30) according to the present invention includes a first opening (30h1) through which the first end (20e1) is exposed and a second opening (30h2) through which the second end (20e2) is exposed.

The first opening (30h1) according to the present invention may include a color-indicating material inside thereof. Specifically, by including a color-indicating material inside the first opening, it is possible to optically confirm that an electrochemical oxidation-reduction reaction spontaneously proceeds in a galvanic cell.

Specifically, the color indicator material may include at least one of a chromogenic material and a fluorogenic material. According to one embodiment of the present invention, since the color indicator material includes at least one of a chromogenic material and a fluorogenic material, it is possible to optically confirm that an electrochemical oxidation-reduction reaction spontaneously proceeds in a galvanic cell.

For example, the chromophore may include 4-chloro-1-naphthol (4-CN), 3,3′,5,5′-tetramethylbenzidine (TMB), etc. Here, the chromophore may be oxidized by being modified by nanoparticles in which both the first end and the second end are encapsulated with a dendrimer. According to one example, 4-chloro-1-naphthol (4-CN) may be oxidized to form benzo-4-chlorohexadienone (4-CD), and at this time, benzo-4-chlorohexadienone may exhibit a purple color.

For example, the fluorescent substance may include Acetyl-3,7-dihydroxyphenoxazine (Amplex Red). Here, the fluorescent substance may be oxidized by modifying both the first end and the second end by the catalyst particle. According to one example, Acetyl-3,7-dihydroxyphenoxazine may be oxidized and converted to Resorufin (RSF), and at this time, the Resorufin (RSF) exhibiting a pink color may exhibit fluorescence.

The second opening (30h2) according to the present invention may include a target material therein. Here, the target material may be a material that can be reduced by receiving electrons from the oxidation electrode of the bipolar electrode-based galvanic cell. Specifically, the purpose of the bipolar electrode-based galvanic cell may vary depending on the type of the target material.

For example, the target material may include an oxygen solution or a hydrogen peroxide solution. Here, oxygen or hydrogen peroxide contained in the target material may undergo a reduction reaction in which it receives electrons and is converted into water.

The bipolar electrode-based galvanic cell (100) according to the present invention may further include a salt bridge (40) connecting the color indicator material and the target material.

The salt bridge according to the present invention can contribute to the generation of electric current by resolving the imbalance of ions by acting as an ion passage. The salt bridge can maintain the electrical neutrality of the internal circuit by precisely offsetting the accumulation of charges and quickly achieving equilibrium by causing the cations of the salt bridge to move toward the reduction electrode and the anions to move from the reduction electrode to the salt bridge. If the salt bridge is not used, as the battery reaction progresses, positive charges will be accumulated in one half-cell and negative charges will be accumulated in the opposite half-cell, and the reaction will soon stop, which will also cause the production of electricity to stop.

2. Hydrogen peroxide sensor

According to another aspect of the present invention, a hydrogen peroxide sensor including a bipolar electrode-based galvanic cell can be provided. Specifically, a cell potential (△E=E _cathode -E _anode ) due to a potential difference between a first end, which is an oxidation electrode, and a second end, which is a reduction electrode, may become higher than 0, so that a spontaneous oxidation-reduction reaction may proceed. Specifically, a color indicator material filled in a first opening corresponding to the first end may be oxidized and lose electrons. The electrons lost through the oxidation reaction may move to the second end through the bipolar electrode. At this time, the moved electrons may react with a hydrogen peroxide solution included in the second opening to generate water. When the bipolar electrode-based galvanic cell according to one aspect of the present invention is used, hydrogen peroxide can be sensed quickly.

FIG. 2 is a schematic diagram of a hydrogen peroxide sensor including a bipolar electrode-based galvanic cell according to one embodiment of the present invention.

Referring to Fig. 2, when the first end where the oxidation reaction occurs is modified with a catalyst particle, the potential at which the oxidation reaction occurs can increase in the negative direction, and when the second end where the reduction reaction occurs is modified with a catalyst particle, the potential at which the reduction reaction occurs can increase in the positive direction. As a result, when the first and second ends are modified in the same way with Pt nanoparticles encapsulated with a dendrimer, the cell potential (△E = E _cathode -E _anode ) becomes higher than 0, so that an oxidation-reduction reaction can occur spontaneously.

3. Screening device for catalyst for oxygen reduction reaction

According to another aspect of the present invention, a screening device for an oxygen reduction reaction catalyst including a bipolar electrode-based galvanic cell can be provided. Specifically, a cell potential (△E=E _cathode -E _anode ) due to a potential difference between a first end, which is an oxidation electrode, and a second end, which is a reduction electrode, becomes higher than 0, so that a spontaneous oxidation-reduction reaction can proceed. Specifically, a color indicator material filled in a first opening corresponding to the first end can be oxidized and lose electrons. The electrons lost through the oxidation reaction can move to the second end through the bipolar electrode. At this time, the moved electrons can react with an oxygen-saturated solution included in the second opening to generate water. A device capable of rapidly screening an oxygen reduction reaction catalyst can be implemented based on this principle.

Hereinafter, embodiments of the present invention will be described in detail so that a person having ordinary skill in the art to which the present invention pertains can easily implement the present invention, but this is only an example, and the scope of the rights of the present invention is not limited by the following contents.

[Synthesis Example 1-1: Nanoparticles encapsulated with dendrimer (Pt ₂₀₀ ) Synthesis]

For a 10 μM sixth-generation polyamidoamine dendrimer (amine-terminated sixth-generation polyamidoamine dendrimers from Sigma-Aldrich), a K ₂ PtCl ₄ aqueous solution corresponding to 200 mol equivalents was added, and the mixture of platinum ions and dendrimers was stirred for 76 hours. That is, a mixture of platinum ions and dendrimers was prepared by coordinating platinum ions with amine groups inside the dendrimer. Thereafter, an NaBH ₄ aqueous solution in an amount exceeding about 20 times the stoichiometric amount was slowly added to the mixture of platinum ions and dendrimers while vigorously stirring, and the platinum ions were completely reduced by leaving it in a sealed container for 24 hours. As a result, the obtained dendrimer-encapsulated platinum nanoparticle solution was dialyzed through cellulose dialysis sacks to remove impurities and obtain a purified dendrimer-encapsulated platinum nanoparticle solution (hereinafter referred to as 'Pt ₂₀₀ ').

[Synthesis Example 2: Nanoparticles encapsulated with dendrimer (Au ₂₀₀ ) Synthesis]

To a 10 μM sixth-generation polyamidoamine dendrimer (Amine-terminated sixth-generation polyamidoamine dendrimers from Sigma-Aldrich) aqueous solution, an HAuCl ₄ aqueous solution corresponding to 200 mol equivalents was added, and the mixture was stirred for 20 minutes. Thereafter, an NaBH ₄ aqueous solution corresponding to 20 mol equivalents of the gold ion precursor was added, and the gold ions were reduced for 20 minutes. The dendrimer-encapsulated gold nanoparticle solution obtained in the same manner as in Synthetic Example 1-1 was purified by dialysis, and as a result, an aqueous solution of dendrimer-encapsulated gold nanoparticles (hereinafter referred to as 'Au ₂₀₀ ') was obtained.

[Manufacturing Preparation Example 1: Manufacturing of a Bipolar Electrode with Both the First and Second Ends Modified]

Hereinafter, for convenience of explanation, indium tin oxide is named 'ITO' and the indium tin oxide layer is named 'ITO layer'.

(a) Step: Manufacturing an ITO microband bipolar electrode;

First, an ITO-coated glass slide was ultrasonically washed with acetone, ethanol, and deionized water in that order, and then dried under a nitrogen flow. Next, the dried ITO-coated glass slide was washed with a plasma cleaner at medium power for 2 minutes, and a photoresist composition (Merck AZ P4330-RS) was spin-coated on the ITO-coated glass slide at 6,000 rpm for 30 seconds. The spin-coated photoresist composition was baked at 115°C for 5 minutes, and the resultant was placed on a photomask aligner and exposed to ultraviolet light for 180 seconds. The exposed photoresist film was developed with a developer (Merck AZ 400K (1:4)) for 8 minutes, and the developed resultant was rinsed with deionized water and baked at 90°C for 5 minutes. Next, the glass slide coated with the ITO layer was etched with an etchant (Transene CE-100) at 65°C for 4 minutes, and the photoresist film not exposed to ultraviolet light was removed by acetone. Finally, the glass slide coated with the patterned ITO layer was washed with ethanol and deionized water in that order, to manufacture an ITO microband bipolar electrode with a length of 22 mm and a width of 1 mm.

(b) Step: immobilizing the dendrimer-encapsulated nanoparticles onto the first and second ends of the ITO microband bipolar electrode;

Steps to modify the first section:

To electrically connect the first end (length: 6 mm, width: 1 mm; area: 6 mm ² ) and the second end opposite to it, a conductive adhesive tape was attached to the first end for electrical connection with a potentiostat. To modify the first end of the ITO microband bipolar electrode, the electrode was exposed to a solution of first nanoparticles (10 μM) encapsulated with a dendrimer containing LiClO ₄ (0.1 M), and then cycled three times between 1.20 V and 1.75 V (Ag/AgCl) by cyclic voltammetry to induce chemical bonding between the terminal amine groups of PtDENs and the first end. The ITO microband bipolar electrode with the modified first end was rinsed with deionized water, sonicated in deionized water for 10 min, and then dried under a nitrogen stream.

Steps to modify the second section:

Thereafter, in order to modify the second end (length: 6 mm; width: 1 mm; area: 6 mm ² ) opposite to the first end, a second nanoparticle solution (10 μM) encapsulated with a dendrimer was used for modification in the same manner as described above. As a result, an ITO bipolar electrode in which both the first end and the second end were modified was manufactured.

[Example 1: Fabrication of a bipolar electrode-based galvanic cell]

The cover part made of polydimethylsiloxane (hereinafter referred to as 'PDMS') was cast using a 3D mold manufactured by a 3D printer device (Ender-3 Pro). A mixture of PDMS monomers and a curing agent (Dow Silicon Cones SYLGARD ^TM 184 silicone elastomer) in a weight ratio of 10:1 was poured into the 3D mold in a petri dish, and then cured at 50° C. for 4 hours to manufacture a preliminary PDMS cover part. After cutting the preliminary PDMS cover part to a suitable size, it was attached to an ITO bipolar electrode according to Manufacturing Preparation Example 1 so that the first end and the second end were exposed to the outside, thereby forming a first opening (oxidation reaction part) and a second opening (reduction reaction part).

[Example 2: Hydrogen peroxide sensor]

Example 2-1: When the first opening is filled with a color developing reagent

In the bipolar electrode-based galvanic cell according to Example 1, 80 mM N ₂ -purged phosphate buffer (pH 7.4) containing 3 mM 4-chloro-1-naphthol (4-CN), a chromogenic reagent, was filled into the first opening, and 100 mM acetate buffer (pH 4.0) containing H ₂ O ₂ target solutions was filled into the second opening. Here, the acetate buffer was purged with nitrogen prior to the chromogenic reaction.

Example 2-2: When the first opening is filled with fluorescent reagent

In the bipolar electrode-based galvanic cell according to Example 1, 90 mM N ₂ -purged phosphate buffer (pH 7.4) containing 1 mM Acetyl-3,7-dihydroxyphenoxazine (Amplex Red), a fluorescent reagent, was filled into the first opening, and 100 mM acetate buffer (pH 4.0) containing H ₂ O ₂ target solutions was filled into the second opening. Here, the acetate buffer was purged with nitrogen prior to the fluorescence reaction.

[Example 3: Screening device for catalyst for oxygen reduction reaction]

Example 3-1: When the first opening is filled with a color developing reagent

In the bipolar electrode-based galvanic cell according to Example 1, 80 mM N ₂ -purged phosphate buffer (pH 7.4) containing 3 mM 4-chloro-1-naphthol (4-CN), a chromogenic reagent, was filled into the first opening, and 100 mM acetate buffer (pH 4.0) saturated with oxygen was filled into the second opening.

Example 3-2: When the first opening is filled with fluorescent reagent

In the bipolar electrode-based galvanic cell according to Example 1, the first opening was filled with 90 mM N ₂ -purged phosphate buffer (pH 7.4) containing 1 mM Acetyl-3,7-dihydroxyphenoxazine (Amplex Red (AR)), a fluorescent reagent, and the second opening was filled with 100 mM acetate buffer (pH 4.0) saturated with oxygen.

[Experimental Example 1: Hydrogen peroxide sensing principle of Example 2-2]

Figure 3 is an optical image of a specimen (i) in which the first end and the second end of the hydrogen peroxide sensor of Example 2-2 are modified with Synthesis Example 1-1 (Pt ₂₀₀ ), a control specimen (ii) in which the second end is modified with Synthesis Example 2 (Au ₂₀₀ ) unlike the specimen (i), and a control specimen (iii) in which the second opening is not filled with a hydrogen peroxide solution unlike the specimen (i).

Referring to FIG. 3, it can be confirmed that only in specimen (i), unlike the control specimens (ii) and (iii), the colorless Amplex Red (AR) oxidation reaction and the hydrogen peroxide reduction reaction spontaneously and simultaneously proceed, thereby causing the solution filled in the first opening to change to pink. Specifically, by comparing specimens (i) and (ii), it can be inferred that when the second end is modified with Synthesis Example 1-1 (Pt ₂₀₀ ), the cell potential (△E = E _cathode -E _anode ) becomes higher than 0, and thus the oxidation-reduction reaction occurs spontaneously. If the second end is modified with Synthesis Example 2 (Au ₂₀₀ ), it can be inferred that the cell potential (△E = E _cathode -E _anode ) becomes lower than 0, and thus the oxidation-reduction reaction does not occur spontaneously.

In addition, in the case of the control specimen (iii), since the second opening did not contain a hydrogen peroxide solution, there was no target substance to receive electrons, and thus the oxidation-reduction reaction did not proceed.

[Experimental Example 2: Measurement of fluorescence intensity according to the concentration of hydrogen peroxide]

FIG. 4 is a fluorescence (x10 ³ au) spectrum that changes as the concentration of hydrogen peroxide is adjusted from 50 to 2,000 μM in the hydrogen peroxide sensor of Example 2-2. Here, both the first end and the second end of the hydrogen peroxide sensor of Example 2-2 were modified with Synthesis Example 1-1 (Pt ₂₀₀ ). Specifically, to analyze the fluorescence spectrum, a FluoroMate FS-2 fluorometer (Scinco Co., Ltd., Korea) was used, and the analysis was performed under the conditions of a reaction time of 20 minutes, an excitation wavelength of 520 nm, and a PMT voltage of 550 V.

Referring to Figure 4, it can be confirmed that the fluorescence intensity linearly increases as the concentration of hydrogen peroxide increases. Specifically, the result of plotting the concentration of hydrogen peroxide and the fluorescence intensity shows a correlation coefficient of 0.997.

[Experimental Example 3: UV-vis absorption spectrum of hydrogen peroxide sensor]

Figure 5 (a) is a reaction scheme in which 4-chloro-1-naphthol (4-CN) is oxidized and converted into benzo-4-chlorohexadienone (4-CD) in the presence of Pt nanoparticles.

Figure 5 (b) shows the UV-vis absorption spectrum results of the hydrogen peroxide sensor of Example 2-1. In Figure 5 (b), i is the UV-vis absorption spectrum before filling the second opening with a 3 mM hydrogen peroxide solution, and ii is the UV-vis absorption spectrum after filling the second opening with a 3 mM hydrogen peroxide solution. Here, the reaction time was adjusted to 5 minutes, and both the first and second ends were modified with Synthesis Example 1-1 (Pt ₂₀₀ ). In addition, an Agilent 8453 UV-Vis spectrometer was used as the analysis equipment.

Figure 5 (c) is a colorimetric intensity profile of the hydrogen peroxide sensor of Example 2-1 according to the concentration of hydrogen peroxide. Here, the reaction time was adjusted to 3 minutes, and both the first and second ends were modified with Synthesis Example 1-1 (Pt ₂₀₀ ).

Referring to (c) of Fig. 5, when filling the second opening with i, ii, and iii, a 3 mM hydrogen peroxide solution, ii, and iii, respectively, a 0.3 mM hydrogen peroxide solution, it is possible to confirm the color change that occurs in the solution filled in the first opening. Specifically, it can be confirmed that the higher the concentration of hydrogen peroxide, the more vivid the color appears.

[Experimental Example 4: Electrochemical Analysis of the Hydrogen Peroxide Sensor of Example 2-2]

Figure 6 (a) is a schematic diagram showing the oxidation-reduction reaction of the hydrogen peroxide sensor of Example 2-2. Here, the first and second ends of the hydrogen peroxide sensor of Example 2-2 were both modified with Synthesis Example 1-1 (Pt ₂₀₀ ).

Referring to (a) of FIG. 6, it can be confirmed that the potential of the first end where the oxidation reaction occurs is increased by modifying the first end with Synthesis Example 1-1 (Pt ₂₀₀ ), and the potential of the second end where the reduction reaction occurs is decreased by modifying the second end with Synthesis Example 1-1 (Pt ₂₀₀ ). As a result, it can be confirmed that a spontaneous oxidation-reduction reaction proceeds when the potential of the first end, which is an oxidation electrode, is set higher than the potential of the second end, which is a reduction electrode. Specifically, the AR filled in the first opening corresponding to the first end can be oxidized to RSF (Resorufin) and lose electrons. The electrons lost through the oxidation reaction can move to the second end through the bipolar electrode. At this time, the moved electrons can react with the hydrogen peroxide solution included in the second opening to generate water.

FIG. 6(b) is a cyclic voltammogram of a three-electrode system including the hydrogen peroxide sensor (ii, iv) of Example 2-2. Specifically, the bipolar electrode of Example 2-2 was used as a working electrode, Ag/AgCl (3 M NaCl) as a reference electrode, and a coiled-Pt wire as a counter electrode, and both the first and second ends were modified with Synthesis Example 1-1 (Pt ₂₀₀ ). Here, (i) and (iii) serve as controls for (ii) and (iv), respectively, and ITO electrodes that were not modified with dendrimer-encapsulated nanoparticles were used. In cases of (i) and (ii), the concentration of hydrogen peroxide was controlled to 2 mM, and in cases of (iii) and (iv), the concentration of AR was controlled to 1 mM.

Referring to (b) of Fig. 6, unlike (i), in the case of (ii), the ITO electrode was modified with Synthesis Example 1-1 (Pt ₂₀₀ ) to exhibit a higher onset potential in the positive direction, thereby easily controlling the reduction reaction of hydrogen peroxide.

In addition, unlike (iii), in the case of (iv), it can be confirmed that the ITO electrode is modified with Synthesis Example 1-1 (Pt ₂₀₀ ), thereby exhibiting a higher onset potential in the negative direction for the electrochemical oxidation reaction of Amplex Red.

Therefore, it can be confirmed that the hydrogen peroxide sensor (ii, iv) of Example 2-2 including the ITO electrode modified with Synthesis Example 1-1 (Pt ₂₀₀ ) exhibited a △E _onset (=E _onset ^H2O2 -E _onset ^AR ) of +0.13 V, and the device including the ITO electrode not modified with Synthesis Example 1-1 (Pt ₂₀₀ ) exhibited a △E _onset of -0.87 V.

Figure ₆ (c) shows the results of ^cyclic voltammetry applied to (i) a _three- electrode system specimen including an ITO electrode as a working electrode and (ii) a three-electrode system specimen including a Pt/ITO electrode, wherein 100 mM KNO 3 containing 1 mM [Fe(CN) 6 ] 3- was used. Here, Ag/AgCl (3 M NaCl) was used as the reference electrode and coiled-Pt wire was used as the counter electrode, and the scan rate was 20 mV/s.

Referring to Fig. 6 (c), it can be confirmed that both the ITO electrode (i) and the Pt/ITO electrode (ii) exhibited similar electron transfer rates when electrical conductivity was not a limiting factor.

Considering the above experimental results comprehensively, it can be inferred that the main factor for the electrochemical activity of the hydrogen peroxide sensor is not the electrical conductivity of the Pt/ITO electrode, but the modification of the first and second ends with dendrimer-encapsulated nanoparticles.

[Experimental Example 5: Screening device for catalyst for oxygen reduction reaction]

Figure 7 (a) is a schematic diagram showing the spontaneous oxidation-reduction reaction of the screening device for the oxygen reduction reaction catalyst of Example 3-2.

Referring to (a) of FIG. 7, when the first end is modified with Synthesis Example 1-1 (Pt ₂₀₀ ), the first end where the oxidation reaction occurs can exhibit a higher onset potential in the negative direction, and when the second end where the reduction reaction occurs is modified with Synthesis Example 1-1 (Pt ₂₀₀ ), it can exhibit a higher onset potential in the positive direction for the reduction reaction. As a result, it can be confirmed that a spontaneous oxidation-reduction reaction proceeds when the cell potential (△E = E _cathode -E _anode ) due to the potential difference between the first end, which is the oxidation electrode, and the second end, which is the reduction electrode, becomes higher than 0. Specifically, the AR filled in the first opening corresponding to the first end can be oxidized to RSF and lose electrons. The electrons lost through the oxidation reaction can move to the second end through the bipolar electrode. At this time, the moved electrons can react with the oxygen-saturated solution included in the second opening to generate water. A device capable of screening a catalyst for oxygen reduction reaction can be implemented using this principle.

Figure 7 (b) shows the cyclic voltammetry results of the three-electrode system of the screening device (ii) of the oxygen reduction reaction catalyst of Example 3-2 and the control groups (i) and (iii) specimens. In the case of (ii), specifically, the bipolar electrode of Example 3-2 was used as the working electrode, Ag/AgCl (3 M NaCl) as the reference electrode, and a coiled-Pt wire as the counter electrode, and both the first and second ends were modified with Synthesis Example 1-1 (Pt ₂₀₀ ). Here, (i) is the control group of (ii), and an ITO electrode that was not modified with dendrimer-encapsulated nanoparticles was used. (iii) is a specimen including 90 mM N ₂ -purged phosphate buffer (pH 7.4) containing 1 mM AR on a Pt/ITO electrode.

Referring to (b) of Fig. 7, the (ii) specimen easily controlled the reduction reaction of oxygen by exhibiting a higher onset potential than the (i) specimen, similar to the reduction reaction of hydrogen peroxide. Specifically, in the case of the (ii) specimen, through △E _onset (=E _onset ^O2 -E _onset ^AR ) of +0.12 V, AR was oxidized to RSF (Resorufin) and showed red fluorescence, and at the same time, it could be confirmed that a spontaneous electrochemical reaction, which is an oxygen reduction reaction in which oxygen receives electrons and is converted to water, was in progress.

Figure 7 (c) is an optical image of the screening device (i) of the oxygen reduction reaction catalyst of Example 3-2, in which the second opening was filled with 100 mM acetate buffer (pH = 4.0) saturated with oxygen and the reaction time was 1 minute, and the control device (ii) in which the second opening was filled with 100 mM acetate buffer (pH = 4.0) saturated with nitrogen, unlike the device (i).

Referring to Fig. 7(c), it can be confirmed that when the second opening is filled with an oxygen-saturated solution, the AR filled in the first opening is oxidized to RSF, resulting in red fluorescence. On the other hand, when the second opening is filled with a nitrogen-saturated solution, no red fluorescence is observed. This suggests that oxygen can be selectively screened.

[Synthesis examples 1-2 to 1-4: Nanoparticles encapsulated with dendrimer (Pt ₃₅₀ , Pt ₅₅₀ , Pt ₁₃₂₀ ) Synthesis]

Dendrimer-encapsulated nanoparticles were synthesized by a method similar to Synthesis Example 1-1 as follows. Cu(NO3)2 corresponding to 55 mol equivalents was added to a 1 μM nitrogen-saturated aqueous solution of hydroxyl-terminated sixth-generation polyamidoamine dendrimers (Sigma- _Aldrich ). Then, _K2PtCl4 aqueous solutions corresponding to 350 mol, 550 mol, and 1320 mol equivalents were added respectively, and the mixture was stirred for 5 minutes. Thereafter, _{NaBH4 aqueous} solution having the same molar equivalents as the _Pt2 ⁺ precursor was added, and the metal ion was reduced for 5 minutes. At this time, the Cu2 ⁺ precursor exists in a Cu2 ⁺ ion state through a galvanic reaction with Pt2 ⁺ , and the Pt2 ⁺ precursor ion is reduced to form platinum nanoparticles. By adding HClO ₄ corresponding to 4 mol equivalents of NaBH ₄ , BH ₄ ^- that could exist in the solution in an unreacted state was oxidized.

[Comparative Synthesis Example 1: Preparation of Commercial Fuel Cell Catalyst]

Pt/C (10 wt%), a commercial catalyst for fuel cells, was prepared.

[Experimental Example 6: Observation of changes in fluorescence intensity according to different types of nanoparticles]

FIG. 8 (a) is a schematic diagram of a galvanic cell based on a bipolar electrode of Example 3, in which a circular first end is modified with Synthesis Example 1-1 (Pt ₂₀₀ ), and a fan-shaped second end is modified with Synthesis Example 1-2 (Pt ₃₅₀ ), Synthesis Example 1-3 (Pt ₅₅₀ ), Synthesis Example 1-4 (Pt ₁₃₂₀ ), Synthesis Example 2 (Au ₂₀₀ ), and Comparative Synthesis Example 1 (Pt/C), respectively. FIG. 8 (b) is an optical microscope photograph of the first end (Anode) of FIG. 8 (a). Here, AR is filled in the first opening corresponding to the first end. FIG. 8 (c) shows the fluorescence intensity of each white circle (i~v) region over time (s) in FIG. 8 (b). Figure 8(d) is a 3D confocal fluorescence image at 3.8 s of the first end region. Here, the first opening corresponding to the circular first end was filled with a nitrogen-purged phosphate buffer (pH=7.4) containing 50 μM AR, and the second opening was filled with an oxygen-saturated 100 mM acetate buffer (pH=4.0).

Referring to (a) to (d) of FIG. 8, it can be confirmed that the fluorescence intensity of the first end (Anode) region is high in the order of Synthesis Example 1-4 (Pt ₁₃₂₀ ), Synthesis Example 1-3 (Pt ₅₅₀ ), Comparative Synthesis Example 1 (Pt/C), Synthesis Example 1-2 (Pt ₃₅₀ ), and Synthesis Example 2 (Au ₂₀₀ ). That is, it can be inferred that the fluorescence intensity changes by adjusting the equivalent amount of the K ₂ PtCl ₄ aqueous solution in the process of synthesizing nanoparticles encapsulated with dendrimers.

Figure 8 (e) is an image in which the upper image, which is a fluorescence image, and the lower image, which is an optical image, are combined during the experiment of Figures 8 (a) to (d).

Referring to Fig. 8 (e), it can be confirmed that all processes of the catalyst for oxygen reduction reaction can be screened within 7 seconds when using the bipolar electrode-based galvanic cell of Example 3.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

10: Substrate
20e1: Part 1
20e2: Part 2
20c: Central
20: Bipolar electrode
30: Cover part
30h1: 1st opening
30h2: 2nd opening
40: Salt bridge
100: Galvanic cell based on bipolar electrodes

Claims (11)

substrate;
A bipolar electrode disposed on the substrate and including a first end part and a second end part opposite to the first end part; and
A cover part covering between the first end and the second end; including;
The above cover part,
A first opening through which the first end is exposed, and
comprising a second opening through which the second end is exposed;
The above first and second sections,
Modified with identical or different catalyst particles,
Galvanic cell based on bipolar electrodes.
In the first paragraph,
The above first section is an oxidation electrode,
The above second section is a reduction electrode,
Galvanic cell based on bipolar electrodes.
In the first paragraph,
The above catalyst particles
A first nanoparticle modifying the first section and
Comprising a second nanoparticle that modifies the second end,
Galvanic cell based on bipolar electrodes.
In the third paragraph,
The first and second nanoparticles,
Each independently encapsulated nanoparticle or core-shell structured nanoparticle is a single metal, alloy multi-metal, dendritic nanoparticle,
Galvanic cell based on bipolar electrodes.
In paragraph 4,
The above single metal
Containing any one selected from the group consisting of Pt, Au, Pd, Ni, Fe and Cu,
The above alloy multi-metal and core-shell structure nanoparticles are each independently
Containing two or more selected from the group consisting of Pt, Au, Pd, Ni, Fe and Cu.
Galvanic cell based on bipolar electrodes.
In the first paragraph,
The above first opening includes a color indicator material inside,
The above second opening contains a target material inside it.
Galvanic cell based on bipolar electrodes.
In Article 6,
The above color indicator material is,
Containing at least one of a chromogenic material and a fluorogenic material,
Galvanic cell based on bipolar electrodes.
In Article 6,
The above target material is,
Containing oxygen solution or hydrogen peroxide solution
Galvanic cell based on bipolar electrodes.
In the first paragraph,
further comprising a salt bridge;
Galvanic cell based on bipolar electrodes.
A hydrogen peroxide sensor comprising a bipolar electrode-based galvanic cell according to any one of claims 1 to 9.
A screening device for a catalyst for oxygen reduction reaction comprising a galvanic cell based on a bipolar electrode according to any one of claims 1 to 9.