WO2022158803A1

WO2022158803A1 - Double-coated catalyst electrode for electrolysis and manufacturing method therefor

Info

Publication number: WO2022158803A1
Application number: PCT/KR2022/000817
Authority: WO
Inventors: 박석원; 김성태; 권경안; 이상훈; 김대원; 조병원; 오시형; 하정훈; 이화영
Original assignee: 주식회사 테크로스; 한국과학기술연구원
Priority date: 2021-01-21
Filing date: 2022-01-17
Publication date: 2022-07-28
Also published as: KR20220105939A; KR102491154B1

Abstract

The present invention relates to a method for manufacturing a catalyst electrode for electrolysis by double-coating of a catalyst through electrospinning deposition (ESD) and physical vapor deposition (PVD), and to a catalyst electrode for electrolysis manufactured by the method.

Description

Double-coated catalyst electrode for electrolysis and manufacturing method thereof

The present invention relates to a method for manufacturing a double-coated catalyst electrode using electrospinning deposition (ESD) and physical vapor deposition (PVD) methods, and to a catalyst electrode for electrolysis manufactured by the method.

Research on hydrogen energy along with solar energy, wind energy, and tidal energy as interest in renewable energy to replace existing fossil fuels that emit environmental pollutants (SO _x , NO _x , CO ₂ and CO, etc.) increases is being actively pursued. In particular, in the case of hydrogen (H ₂ ) energy, it can solve the problem of unstable power supply of intermittently produced renewable energy, and since the combustion product is water (H ₂ O), it is in the spotlight as an eco-friendly energy. In addition, on a mass basis, the energy content of hydrogen is 2.8 times higher than that of diesel and has the highest mass energy density at 120 MJ/m ³ (liquid), which is 2.5 times higher than that of natural gas. However, it has a relatively low volumetric energy density of 40% and 23% of natural gas and diesel on an equal volume basis.

Therefore, in order to efficiently use hydrogen energy, the hydrogen storage system for transportation must be improved depending on the type of use of compressed hydrogen, liquid hydrogen, LNG, methanol, metal hydride, LOHC, etc. There needs to be a way to

On the other hand, the water electrolysis reaction includes an oxygen evolution reaction (OER) and a hydrogen evolution reaction (HER).

[Formula 1] Water electrolysis reaction

Oxygen generating electrode: 2H ₂ O → O ₂ + 4H ⁺ + 4e ^-

Hydrogen generating electrode: 4H ⁺ + 4e ^- → 2H ₂

[Formula 2] Oxygen evolution reaction (OER) voltage

In particular, since an overpotential higher than the theoretical oxygen evolution reaction voltage (Formula 2) occurs due to a slower reaction rate in the oxygen evolution reaction than in the hydrogen evolution reaction in the water electrolysis reaction, iridium oxide (IrO ₂ ), ruthenium oxide ( RuO ₂ ) and expensive noble metal catalysts such as platinum (Pt) are used.

Therefore, although many studies have been conducted on non-noble metal catalysts that are inexpensive and have activity and stability as high as noble metal catalysts, they cannot replace the complete noble metal catalyst. Therefore, there is a need to develop a noble metal reduction catalyst electrode that increases the activity of the catalyst while efficiently reducing the amount of the noble metal catalyst.

As a prior document related to an oxygen generating electrode, in Korean Patent Application Laid-Open No. 10-2020-0047279, a platinum (Pt) layer is first electroplated on a titanium electrode, and an iridium oxide (IrO ₂ ) layer is formed thereon through electroplating. Disclosed is a method for manufacturing a generating electrode. Korean Patent No. 10-0947892 discloses a process for manufacturing an electrode using electrospinning.

An object of the present invention is to increase the activity of a noble metal catalyst by double coating the catalyst using electrospinning deposition (ESD) and physical vapor deposition (PVD), and to reduce the content of noble metal double for electrolysis To provide a method for manufacturing a coated catalyst electrode.

Another object of the present invention is to provide a method capable of reducing the content of noble metals by double coating a catalyst on an electrode.

The above-described task, the steps of preparing a coating solution containing one or more metal compounds; forming a metal oxide layer by coating the coating solution on a titanium electrode by an electrospinning deposition (ESD) method and then performing heat treatment; and forming a platinum (Pt) layer on the metal oxide layer using a physical vapor deposition (PVD) method.

Preferably, the metal compound is iridium (Ir), ruthenium (Ru), palladium (Pd), titanium (Ti), tin (Sn), tantalum (Ta), antimony (Sb) and manganese (Mn). It may include one or more metals selected from the group consisting of.

Also preferably, the coating solution may be prepared by mixing at least one metal compound, a conductive agent, an organic solvent, and a binder solution.

Also preferably, the forming of the platinum layer may include depositing platinum on the surface of the metal oxide layer by evaporating a high-purity platinum target using plasma in a vacuum chamber at room temperature.

Also preferably, the catalyst electrode coating solution may be prepared by mixing at least one metal compound, a conductive agent, an organic solvent, and a binder solution.

Also preferably, the thickness of the platinum layer may be 25 nm to 1 μm.

Also preferably, the titanium electrode may be of a general plate material, a regular perforated network, a perforated perforated network, an expanded wire mesh type or a mesh type.

In addition, an object of the present invention is prepared by the above method, and comprising a double-coated catalyst layer with a titanium electrode, a metal oxide layer formed on the titanium electrode, and a platinum layer formed on the metal oxide layer, by a double-coated catalyst electrode for electrolysis. is achieved

According to the method of the present invention, by forming a thin double-structured catalyst layer through electroradiation and physical vapor deposition, the use of precious metals is reduced and the activity of the catalyst electrode is increased, thereby solving the problem of price, which is a problem of insoluble electrodes for electrolysis, It is expected to contribute to the catalyst electrode industry for electrolysis.

1 is a reaction schematic diagram showing a general water electrolysis operation.

2 is a schematic diagram of an electrospray deposition (ESD) apparatus used in the present invention.

3 is a schematic diagram of a physical vapor deposition (PVD) apparatus used in the present invention.

4 is a diagram illustrating a cross-section of a catalyst electrode manufactured by the method according to the present invention.

5 is an SEM image and elemental analysis data of the titanium electrode used in the present invention.

6 is an SEM image and elemental analysis data of the double-coated catalyst electrode prepared in Example 1. FIG.

7 is an SEM image and elemental analysis data of the double-coated catalyst electrode prepared in Example 2. FIG.

8 is an SEM image and elemental analysis data of the metal oxide-coated catalyst electrode prepared in Comparative Example 1. FIG.

9 is an LSV measurement graph showing changes in current values by applying a voltage to the catalyst electrodes prepared in Examples 1 and 2 and Comparative Example 1 at a rate of 5 mV/s.

10 is a graph showing EIS measurements of the catalyst electrodes prepared in Examples 1 and 2 and Comparative Example 1 in a range of 100 kHz to 50 mHz under a current density of 0.1 A/cm ² .

11 is a graph showing EIS measurements of the catalyst electrodes prepared in Examples 1 and 2 in the range of 100 kHz - 50 mHz at a current density of 0.5 A/cm ² .

All technical terms used in the present invention, unless otherwise defined, have the following definitions and are consistent with the meanings commonly understood by one of ordinary skill in the art of the present invention. In addition, although preferred methods and samples are described herein, similar or equivalent ones are also included in the scope of the present invention.

The term "about" means 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, means an amount, level, value, number, frequency, percentage, dimension, size, amount, weight or length varying by 4, 3, 2 or 1%.

Throughout this specification, unless the context requires otherwise, the terms "comprises" and "comprising" include the steps or elements presented, or groups of steps or elements, but include any other step or element, or It is to be understood that a step or group of elements is meant to be implied not to be excluded.

The present invention relates to a method for manufacturing a double-coated catalyst electrode for electrolysis and a catalyst electrode prepared by the method.

According to an embodiment of the present invention, the double coating catalyst electrode comprises the steps of: preparing a coating solution containing one or more metal compounds; and forming a metal oxide layer by coating the coating solution on a titanium electrode by an electrospinning deposition (ESD) method and then performing heat treatment; and forming a platinum layer on the metal oxide layer by a physical vapor deposition (PVD) method.

The double-coated catalyst electrode according to the present invention protects the oxidation of the electrode by coating the primary metal oxide layer and increases the catalytic activity together with the primary catalyst by coating the secondary platinum layer. In addition, the catalyst layer can be coated without by-products because the platinum layer is coated in a PVD method in a vacuum state.

Preferably, the first metal oxide layer may be formed by depositing a metal compound coating solution on the surface of the titanium electrode by electroradiation at room temperature. At this time, it is preferable that the electroradiation deposition conditions spray the metal compound coating solution at a rate of 0.1 to 10 mL/h under a voltage of about 10 kV to 30 kV. In addition, after the primary metal compound (M-Cl _x ) coating, it is preferable to form a metal oxide through heat treatment at a temperature of 600 ℃ to 800 ℃.

The secondary platinum layer may be formed by evaporating a high-purity platinum target using plasma at room temperature in a vacuum chamber and depositing it on the surface of the metal oxide catalyst electrode through a physical vapor deposition (PVD) method. At this time, the vacuum degree is 1x10 ^-6 Torr or less, and the applied current is preferably in the range of 15 to 50 mA for deposition.

The metal compound coating solution may be prepared by mixing at least one metal compound, a conductive agent, an organic solvent, and a binder solution.

The metal compound is selected from the group consisting of iridium (Ir), ruthenium (Ru), palladium (Pd), titanium (Ti), tin (Sn), tantalum (Ta), antimony (Sb) and manganese (Mn) It may include one or more metals. Preferably, the metal compound having the highest specific gravity among the metal compounds may be IrCl ₂ .

The metal oxide may be a product made by coating the metal compound on a titanium surface and then heat-treating it at a high temperature in air.

The organic solvent may be selected from the group consisting of lower alcohols having 1 to 4 carbon atoms (eg, methanol, ethanol, propanol and butanol) and hydrochloric acid.

The binder solution may be selected from the group consisting of titanium salts such as titanium methoxide, titanium ethoxide, titanium propoxide and titanium butoxide.

The step of forming the metal oxide layer includes depositing the metal compound coating solution on the titanium substrate by an electroradiation deposition method, and then performing heat treatment.

According to an embodiment of the present invention, the step of forming the first metal oxide layer may include depositing the catalyst electrode coating solution by an electroradiation deposition method and then performing heat treatment at 600° C. to 800° C. (1 hour). .

Figure 2 is a method of the present invention, a primary metal oxide (Metal oxide, MO _x ) is a schematic diagram of the electro-radiation deposition (ESD) method for layer coating.

3 is a schematic diagram of a physical vapor deposition (PVD) method for coating a secondary platinum (Pt) layer as a method of the present invention.

4 is a cross-sectional view of an electrode coated with the primary and secondary catalyst layers by the method of the present invention. 4, a metal oxide layer (Metal oxide, MO _x ) is formed on the surface of the titanium electrode (Ti), and a platinum layer is formed on the surface of the metal oxide catalyst.

The method of the present invention reduces the amount of expensive noble metals iridium (Ir) or platinum (Pt) used by forming a second platinum layer on the first coated metal oxide catalyst layer and prepares a double-coated catalyst electrode stable for electrolysis.

In the above, the titanium electrode may include a titanium metal or a titanium alloy having a purity of 100%. The titanium electrode may be of a general plate material, a regular perforated network, a perforated perforated network, an expanded wire mesh type, or a mesh type. In addition, the titanium electrode may be an electrode having a rough surface treated with sand blast or the like in order to increase the reaction area during the electrolysis reaction.

Hereinafter, the present invention will be specifically described with reference to Examples. However, the following examples and accompanying drawings are only examples used to show the state after coating of the present invention, and the electrode coating range or use range of the present invention is not limited by the drawings.

Example 1 - Preparation of Platinum Coated Metal Oxide Catalyst Electrode 1

First, 0.14 g of IrCl ₂ was added to 3 mL of butanol to prepare solution 1, and 0.6 mL of Ti{OCH(CH ₃ )} and 0.015 g of carbon were mixed with 3 mL of HCl and 5 mL of butanol to prepare solution 2. 3 mL of solution 1 prepared by the above method and 6.4 mL of solution 2 were mixed and bathed for 2 hours to prepare a metal compound coating solution.

The metal compound coating solution was deposited on a foam-type titanium electrode at a rate of 1 mL/h under a 10 kV voltage using electro-radiation deposition (ESD) equipment, dried, and then heat-treated at 700° C. for 1 hour to coat a metal oxide layer. Electrodes were prepared.

The titanium electrode with the metal oxide layer prepared by the above method was placed in a vacuum chamber in which a high vacuum of about 1x10 ^-6 Torr was maintained, and a high-purity platinum (99.99%) target was prepared. A current of 15 mA was applied to the electrode and the platinum target for 5 minutes in a vacuum chamber, and the platinum target was evaporated using plasma. Platinum evaporated by the plasma used at this time is in an ionized state, and platinum with a thickness of about 25 nm was deposited on the surface of the metal oxide layer to which a voltage was applied to prepare a double-coated catalyst electrode. The SEM image and EDS analysis data of the titanium electrode having a platinum layer on the surface of the metal oxide layer prepared above are shown in FIG. 6 , and platinum (Pt) including iridium oxide (IrO _x ) and titanium oxide (TiO _x ) in the prepared electrode ), it was confirmed that the element was analyzed.

In addition, in order to fabricate a membrane electrode assembly (MEA) for use in a water electrolysis cell, the catalyst electrode prepared by the above method was used as an oxygen generating electrode, and an electrode spray-coated with Pt/C (50:50) was used as a hydrogen generating electrode. Thus, Nafion (Nafion) membrane was pressed at 100 ° C. for 30 seconds at a pressure of 2 MPa.

In order to evaluate the water electrolysis performance, the MEA prepared by the above method was put into the water electrolysis cell, and distilled water was supplied to both cells at a rate of 10 mL/min at 80 °C. The change in the reaction current was measured while increasing the voltage from 1.3 V to 2.0 V at a rate of 50 mV/s. At this time, the current value change (LSV analysis) according to the voltage increase is the current density and is shown in FIG. 9 .

After LSV analysis by the above method, EIS (Electrochemical Impedance Spectroscopy) analysis was performed in the range of 100 kHz - 50 mHz while applying 0.1 A/cm ² and 0.5 A/cm ² current to the electrolytic cell. 11 shows.

Example 2 - Preparation of platinum-coated metal oxide catalyst electrode 2

The metal compound coating solution was deposited on a foam-type titanium electrode at a rate of 1 mL/h under a voltage of 10 kV using electro-radiation deposition (ESD) equipment, dried, and then heat-treated at 700° C. for 1 hour to coat a metal oxide layer. Electrodes were prepared.

The titanium electrode with the metal oxide layer prepared by the above method was placed in a vacuum chamber in which a high vacuum of about 1x10 ^-6 Torr was maintained, and a high-purity platinum (99.99%) target was prepared. A current of 15 mA was applied to the electrode and the platinum target for 10 minutes in a vacuum chamber, and the platinum target was evaporated using plasma. Platinum evaporated by the plasma used at this time is in an ionized state, and platinum with a thickness of about 50 nm was deposited on the surface of the metal oxide layer to which a voltage was applied to prepare a double-coated catalyst electrode. The SEM image and EDS analysis data of the titanium electrode having a platinum layer on the surface of the metal oxide layer prepared above are shown in FIG. 7 , and platinum (Pt) including iridium oxide (IrO _x ) and titanium oxide (TiO _x ) in the prepared electrode ), it was confirmed that the element was analyzed.

Comparative Example 1 - Preparation of metal oxide catalyst electrode

In the above example, except for the secondary platinum coating, it was prepared in the same manner as in the preparation of the primary metal oxide catalyst-coated electrode. The SEM image and EDS analysis data of the prepared metal oxide catalyst electrode are shown in FIG. 9 , and it was confirmed that iridium oxide (IrO _x ) and titanium oxide (TiO _x ) elements were analyzed in the prepared electrode.

After the LSV analysis by the above method, an EIS (Electrochemical Impedance Spectroscopy) analysis was performed in the range of 100 kHz - 50 mHz while applying a current of 0.1 A/cm ² to the electrolytic cell, as shown in FIG. 10 .

5 is a titanium electrode used in the present invention, a foam-type electrode in which a titanium wire of about 20 um is laminated, and as a result of elemental analysis, titanium was measured as a main element.

6 is an SEM photograph of a catalyst electrode coated with about 25 nm platinum on the iridium oxide and titanium oxide coated electrode prepared in Example 1. As a result of elemental analysis, it is confirmed that the iridium element is coated at least twice that of the platinum element. did.

7 is a SEM photograph of a catalytic electrode coated with about 50 nm platinum on the iridium oxide and titanium oxide coated electrode prepared in Example 2, and as a result of elemental analysis, the iridium element and the platinum element are coated in the same amount at about 1:1. confirmed that it has been

FIG. 8 is an SEM photograph of the iridium oxide and titanium oxide coated electrodes prepared in Comparative Example 1. As a result of elemental analysis, the amounts of iridium and titanium elements were similarly analyzed.

9 is a graph of LSV measurement using the water electrolysis cell of the catalyst electrode prepared in Examples 1 and 2 and Comparative Example 1. FIG. As a result of LSV analysis of the electrode of Comparative Example 1, which is an electrode coated with a primary metal oxide by ESD without a platinum coating, a reaction current of less than about 0.2 A/cm ² was shown up to a final 2.0V. However, in the case of the electrodes of Example 1 (Pt, 25 nm) and Example 2 (Pt, 50 nm) in which a platinum layer was formed secondarily on the electrode of Comparative Example 1, the reaction current densities of 2.5 A/cm ² and 3.5 A/cm ² or more, respectively showed This increased the catalytic activity as the platinum layer was double coated for the insufficient catalytic activity of the electrode coated with the thin iridium oxide layer.

10 is a graph illustrating EIS measurements under the application of 0.1 A/cm ² current using the electrolytic cell of the catalyst electrode prepared in Examples 1 and 2 and Comparative Example 1. FIG. As a result of impedance measurement, Example 1 and Example 2, which are electrodes coated with a secondary platinum layer, showed similar surface resistance characteristics, but it was confirmed that the electrode of Comparative Example 1 coated with only the primary metal oxide layer had a surface resistance that was three times or more. did.

11 is a graph showing EIS measurements under the application of 0.5 A/cm ² current using the electrolytic cell of the catalyst electrode prepared in Examples 1 and 2; Due to the increase in the applied current, the surface resistance of Comparative Example 1 became so large that analysis was impossible, and in the case of the electrode of Example 2 in which the thickness of the secondary coated platinum was 50 nm, about 1 of Example 1 was 25 nm. It showed a surface resistance of /2.

As described above in detail a specific part of the present invention, for those of ordinary skill in the art, this specific description is only a preferred embodiment, and it is clear that the scope of the present invention is not limited thereto. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims

preparing a coating solution containing one or more metal compounds;

forming a metal oxide layer by coating the coating solution on a titanium electrode by an electrospinning deposition (ESD) method and then performing heat treatment; and

and coating platinum (Pt) on the metal oxide layer by a physical vapor deposition (PVD) method to form a platinum layer.

According to claim 1, wherein the metal compound is iridium (Ir), ruthenium (Ru), palladium (Pd), titanium (Ti), tin (Sn), platinum (Pt), tantalum (Ta), antimony (Sb) ) and manganese (Mn), characterized in that it comprises one or more metals selected from the group consisting of, a method for producing a double-coated catalyst electrode for electrolysis.

The method of claim 1, wherein the coating solution is prepared by mixing at least one metal compound, a conductive agent, an organic solvent, and a binder solution.

The method of claim 1, wherein the platinum layer has a thickness of 25 nm to 1 μm.

The method of claim 1, wherein the titanium electrode is a general plate, a regular perforated network, a perforated network, an expanded wire mesh or a mesh type, a method for manufacturing a double-coated catalyst electrode for electrolysis.

A double-coated catalyst electrode for electrolysis, which is prepared by the method of any one of claims 1 to 5 and consists of a double-coated catalyst layer in which a titanium electrode, a metal oxide layer formed on the titanium electrode, and a platinum layer is formed on the metal oxide layer. .