KR102619869B1 - Water electrolysis catalyst and method for preparing the same - Google Patents

Abstract

The present invention relates to a catalyst for water electrolysis and a method for manufacturing the same. More specifically, the present invention relates to a catalyst for water electrolysis and a method for manufacturing the same. More specifically, by stacking a nanowire composite in which a plurality of nanowires are aligned parallel to each other at regular intervals, the electrochemical active area is improved and the electrochemical activity during the water electrolysis reaction is improved. It relates to a catalyst for water electrolysis that does not cause entanglement or agglomeration at all and a method for manufacturing the same.

Description

Catalyst for water electrolysis and method for preparing the same {Water electrolysis catalyst and method for preparing the same}

The present invention relates to a catalyst for water electrolysis and a method for producing the same.

One of the main concerns for commercialization of electrochemical reaction catalysts for water electrolysis is to increase catalyst efficiency compared to the amount of iridium used. However, in order to expand the application area of iridium, the use area of iridium is reduced due to the entanglement phenomenon and electrochemical oxidation of the support (carbon) in the form of nanoparticles such as Ir/C, which are currently used commercially. Durability may decrease. In addition, there is a limitation that it cannot be used as a catalyst for oxygen generation reaction due to high overvoltage.

Among the metal oxide-based supports used as an alternative to carbon-based supports, antimony-doped tin oxide has the thermal and chemical durability of general tin oxide, shows excellent electrical conductivity, and is very inexpensive, so it is used in lithium-ion batteries. It is a material widely used as a support for water electrolysis thin film electrodes and organic light-emitting diode electrodes. In addition, antimony-doped tin oxide can improve transparency, so research is being actively conducted to use it as a transparent electrode material to replace tin-doped indium oxide.

Currently, antimony-doped tin oxide is mainly manufactured through a sputter process or solution-based synthesis process. Using this process has the advantage of being able to obtain antimony-doped tin oxide with excellent crystallinity, but only results in irregular shapes such as thin films or nanoparticles can be obtained, making it difficult to form a three-dimensional nanostructure. If tin oxide doped with random antimony created in this way is applied as a support for an electrochemical reaction catalyst electrode for water electrolysis, the support may collapse or become entangled as the reaction progresses, and for ionic connection between nanoparticles, the support may collapse or become entangled. The use of ionomers is essential, and the use of these additional additives has limitations that ultimately act as a major limitation in the movement of reactants or products between catalysts.

Recently, research was reported on creating three-dimensional nanostructures using antimony-doped tin oxide nanowires in addition to thin films or nanoparticles and applying them to various devices. At the Berlin University of Technology in Germany, antimony-doped tin oxide nanowires were manufactured using electrospinning technology and used as a support for thin film electrodes for water electrolysis to evenly disperse iridium oxide to produce a catalyst with high oxygen reduction efficiency. These catalysts have shown excellent results in terms of durability while reducing the amount of iridium used, but require a complex process of separately synthesizing and combining the support and catalyst, and although they have a three-dimensional structure, they are still not very regular, such as thin films or nanoparticles. Since it can only be manufactured in a certain shape, there was a limitation in that it was difficult to manufacture an aligned structure. Accordingly, technology was developed for a water electrolysis catalyst in the form of an ordered network that prevents entanglement during the reaction, which can reduce the electrochemical active area, promotes the smooth movement of substances such as reactants and products, and does not require the use of additives such as ionomers. This is necessary.

Patent Document 1. Korean Patent Publication No. 10-2021-005806

The present invention was created to solve the above-mentioned problems. The purpose of the present invention is to stack a nanowire composite in which a plurality of nanowires are aligned parallel to each other at regular intervals, so that the electrochemical active area is not only improved, but also the water power is increased. The aim is to provide a catalyst for water electrolysis that does not cause any entanglement or agglomeration during the reaction and has excellent performance and durability and a method for manufacturing the same.

One aspect of the present invention is a catalyst for water electrolysis in which a plurality of nanowire composites are stacked, wherein the nanowire composite is a plurality of nanowires arranged parallel to each other and spaced at regular intervals, and the nanowires are doped with antimony. A catalyst for water electrolysis is provided, comprising a tin oxide layer and an iridium layer.

Another aspect of the present invention includes the steps of (A) preparing a polymer mold on the surface of which irregularities are formed including a plurality of reliefs spaced parallel to each other at regular intervals; (B) manufacturing a multilayer structure by depositing iridium, tin oxide, and antimony on the plurality of reliefs; (C) stacking the multilayer structure 4 to 40 times on a substrate; and (D) preparing a catalyst for water electrolysis by heat treating the multilayer structure laminated on the substrate, wherein the catalyst for water electrolysis is a nanowire composite in which a plurality of nanowires are arranged in parallel and spaced apart from each other at regular intervals. It provides a method of manufacturing a catalyst for water electrolysis, wherein a plurality of nanowires are stacked, and the nanowires include a tin oxide layer and an iridium layer doped with antimony.

The catalyst for water electrolysis according to the present invention has an improved electrochemically active area and does not decrease the electrochemically active area even during reaction, so it can exhibit excellent performance, and durability can be significantly improved due to its laminated structure.

In addition, the method for producing a catalyst for water electrolysis of the present invention can simultaneously deposit and transfer antimony and tin oxide as a carrier and iridium as a catalyst, and manufacture nanowires in an aligned form using a substrate on which a master pattern is formed. The phenomenon of entanglement or agglomeration during electrochemical reactions can be significantly improved.

Figure 1 is a schematic diagram showing a method for producing a catalyst for water electrolysis according to the present invention.
Figure 2 is a schematic diagram showing the manufacturing method of the antimony-doped tin oxide nanowire composite prepared in the production example of the present invention.
Figure 3 is a scanning electron microscope (SEM) image of the top and cross sections of the antimony-doped tin oxide nanowire composite prepared in the preparation example of the present invention.
Figure 4 shows (a) a transmission electron microscope (TEM) image and (b) an energy dispersive analysis (EDS) image of the upper surface of a catalyst for water electrolysis manufactured according to an embodiment of the present invention.
Figure 5 shows an X-ray diffraction (XRD) pattern after deposition and heat treatment of the antimony-doped tin oxide nanowire composite prepared in the preparation example of the present invention.
Figure 6 shows the X-ray photoelectron spectroscopy (XPS) pattern of the antimony-doped tin oxide nanowire composite prepared in the preparation example of the present invention immediately after deposition and after heat treatment.
Figure 7 shows (a) oxygen evolution reaction (OER) performance of a battery using the water electrolysis catalyst prepared in Example 1 and Comparative Examples 1 to 3 of the present invention, and (b) a graph of activity versus mass analysis.
Figure 8 shows a graph showing the results of evaluating the deterioration characteristics of a battery using the water electrolysis catalyst prepared in Example 1 and Comparative Examples 1 to 3 of the present invention.

Hereinafter, the present invention will be described in more detail with the accompanying drawings and examples.

As previously explained, the catalyst carrier used in the conventional water electrolysis catalyst is in the form of nanoparticles in order to have high performance and stability while reducing the amount of precious metal catalyst used, so the use of ionomers is essential for ionic connection between nanoparticles and the reaction As the process progressed, there was a limitation in that entanglement occurred and the catalytic activity area decreased.

Accordingly, the present invention provides a catalyst for water electrolysis that not only maximizes the electrochemically active area, but also exhibits a three-dimensional nanostructure connected to each other without the use of ionomers, so that no entanglement phenomenon or reduction of the electrochemically active area occurs during the reaction.

More specifically, the present invention relates to a catalyst for water electrolysis in which a plurality of nanowire composites are stacked, wherein the nanowire composite is a plurality of nanowires arranged in parallel and spaced at regular intervals, and the nanowires are doped with antimony. Provided is a catalyst for water electrolysis, comprising a tin oxide layer and an iridium layer.

The nanowires may have a pillar shape with a semicircular or polygonal cross section in directions spaced apart from each other.

The iridium layer may be formed on both sides of the antimony-doped tin oxide layer. The iridium layer is desirable in that not only is it electrically connected when formed on both sides of the antimony-doped tin oxide layer, but also the iridium surface can come into contact with the electrolyte, thereby significantly improving the electrochemically active area.

The catalyst for water electrolysis may be a stack of 4 to 40 nanowire composites. If the nanowire composite is stacked with less than 4 pieces, it is undesirable because it is closer to a two-dimensional structure rather than a three-dimensional structure, and the ratio of surface area per volume is too small, and if it is stacked with more than 40 nanowire composites, the bonding force between the nanowire composites decreases, which is undesirable. Desorption between complexes may occur.

The regular interval may be 25 nm to 1 ㎛, preferably 100 to 800 nm, and most preferably 300 to 600 nm. If the spacing is less than 25 nm, the spacing between the nanowire composites may be too close, and as lamination proceeds, the passage for mass transfer may be blocked, resulting in a significant decrease in mass transport speed, or entanglement may occur as the water electrolysis reaction progresses, On the other hand, if it exceeds 1 ㎛, the amount of iridium, which is a catalyst part, per unit area is greatly reduced, which may lead to a decrease in catalytic performance.

The nanowire composite may form an angle of 0˚ to 90˚ with other nanowire composites stacked adjacent to each other. It is most preferable when the nanowire composite forms an angle of 85° to 90° with other nanowire composites stacked adjacent to each other in that the passage of material movement is not blocked compared to other angles.

The antimony-doped tin oxide layer may be doped with 5 to 15 wt% of antimony, preferably 7 to 12 wt%, based on 100 wt% of the antimony-doped tin oxide. If the antimony is doped to less than 5% by weight, electrical conductivity may be significantly reduced, and conversely, if it is doped to more than 15% by weight, durability may be significantly reduced due to antimony precipitation.

The iridium layer may have a thickness of 0.5 to 2 nm, and the antimony-doped tin oxide layer may have a thickness of 10 to 50 nm, preferably 15 to 25 nm. It was confirmed that the catalytic activity area of iridium could be maximized when the thickness of the iridium layer and the antimony-doped tin oxide layer satisfied the above range.

Meanwhile, another aspect of the present invention includes the steps of (A) preparing a polymer mold on the surface of which irregularities are formed including a plurality of reliefs spaced parallel to each other at regular intervals; (B) manufacturing a multilayer structure by depositing iridium, tin oxide, and antimony on the plurality of reliefs; (C) stacking the multilayer structure 4 to 40 times on a substrate; and (D) preparing a catalyst for water electrolysis by heat treating the multilayer structure laminated on the substrate, wherein the catalyst for water electrolysis is a nanowire composite in which a plurality of nanowires are arranged in parallel and spaced apart from each other at regular intervals. It provides a method of manufacturing a catalyst for water electrolysis, wherein a plurality of nanowires are stacked, and the nanowires include a tin oxide layer and an iridium layer doped with antimony.

Figure 1 is a schematic diagram showing a method for manufacturing a catalyst for water electrolysis according to the present invention. Hereinafter, each step of the method for manufacturing a catalyst for water electrolysis of the present invention will be described with reference to Figure 1.

(A) Preparing a polymer mold with irregularities formed on the surface including a plurality of reliefs spaced parallel to each other at regular intervals

The reliefs may be spaced parallel to each other at intervals of 25 nm to 1 ㎛, preferably 100 to 800 nm, and most preferably 300 to 600 nm.

The step (A) is a step of preparing a polymer mold for manufacturing a nanowire composite. (A1) Polydimethylsiloxane (PDMS) is formed on a master mold in which irregularities including a plurality of intaglios corresponding to the plurality of embossings are formed. ) Forming a coating layer; (A2) forming a polymer layer on the polydimethylsiloxane coating layer; And (A3) separating the master mold and the polymer layer to manufacture a polymer mold.

The step (A1) may be performed by spin-coating a solution containing 1 to 5% by weight of polydimethylsiloxane on the upper surface of the master mold and heat treating it at 100 to 200 ° C. for 30 minutes to 2 hours. The polydimethylsiloxane coating layer allows the polymer layer to be completely separated from the master mold.

The step (A2) may be performed by coating a polymer solution containing 1 to 10% by weight of the polymer, preferably 3 to 5% by weight. More specifically, the polymer solution may be a mixture of the polymer and a solvent consisting of toluene, acetone, and heptane in a volume ratio of 3 to 5:3 to 5:1 to 4. If the polymer content is less than 1% by weight, the polymer layer may not be formed, and if it is more than 10% by weight, separation of the master mold and the polymer layer may be difficult.

The step (A3) may involve attaching an adhesive film to the polymer layer and pulling it to separate the polymer layer from the master mold. The adhesive film may be made of polyimide. After attaching an adhesive film to the polymer layer and pulling the adhesive film, the polymer layer can be separated from the master mold, and irregularities that are the reverse image of the master mold can be formed on the polymer layer.

The material of the polymer mold may be any one selected from the group consisting of polymethyl methacrylate (PMMA), poly4-vinylpyridine (P4VP), poly2-vinylpyridine (P2VP), and polystyrene (PS). Preferably it may be polymethyl methacrylate. In particular, polymethyl methacrylate has the advantage that it can be easily separated due to the large difference in surface energy from the master mold, and that it absorbs less moisture in the air than other polymers, making it easy to maintain the shape of the uneven surface.

(B) manufacturing a multilayer structure by depositing iridium, tin oxide, and antimony on the plurality of reliefs.

The step (B) is a step of depositing iridium, tin oxide, and antimony along the plurality of reliefs to form a multilayer structure of an iridium layer, a tin oxide layer, and an antimony layer. The deposition is performed using heat deposition or electron beam deposition. It may be something that is carried out. In particular, electron beam evaporation is the most desirable because, compared to heat evaporation, which only allows for metal types, it is possible to deposit most materials, including metals and metal oxides, and it is much easier to control the deposition thickness in micro units or less.

The step (B) includes (B1) depositing iridium on the plurality of reliefs to form an iridium layer; (B2) forming a tin oxide layer and an antimony layer on the iridium layer, alternately depositing the tin oxide and antimony so that the tin oxide layer is formed on both sides of the antimony layer; and (B3) depositing iridium on the tin oxide layer formed at the top in step (B2). At this time, step (B2) may be repeated multiple times by alternately depositing tin oxide and antimony. For example, as shown in FIG. 1, it can be deposited in the order of iridium layer - tin oxide layer - antimony layer - tin oxide layer - iridium layer, and by increasing the tin oxide layer and antimony layer, iridium layer - tin oxide layer - It can be deposited in the following order: antimony layer - tin oxide layer - antimony layer - tin oxide layer - iridium layer. When the antimony layer is formed between the tin oxide layers, it is preferable that antimony is uniformly diffused into the tin oxide layer through heat treatment in step (D), thereby forming an antimony-doped tin oxide layer.

The rate at which the iridium is deposited in the step (B1) and the step (B3) may be 0.1 to 0.5 Å/s, and the rate at which the tin oxide and antimony are deposited in the step (B2) may be 1.0 to 2.0 Å. It can be /s. When the deposition rate of iridium, tin oxide, and antimony satisfies the above range, nanowires formed by tin oxide and antimony can be created without interruption, and in the case of iridium, it can be evenly deposited on the nanostructure.

(C) stacking the multilayer structure 4 to 40 times on a substrate

It may further include exposing the adhesive film to organic solvent vapor before step (C). More specifically, in order to weaken the adhesive strength of the adhesive film used to separate the polymer layer from the master mold, the adhesive film can be removed by exposing the polymer mold to organic solvent vapor at 50 to 60 ° C. for 10 to 20 seconds. . The organic solvent vapor serves to effectively remove the adhesive film. It was confirmed that the adhesive film was removed without damage to the multilayer structure when the temperature of the organic solvent and the exposure time to the organic solvent satisfied the above range. The organic solvent may be one or more selected from the group consisting of heptane, acetone, and toluene.

Step (C) is a step of stacking the multilayer structure prepared in step (B) 4 to 40 times. At this time, if the multilayer structure is stacked less than 4 times, it is close to a two-dimensional structure rather than a three-dimensional structure, which is undesirable because the ratio of surface area per volume is too small, and if the multilayer structure is stacked more than 40 times, there is a gap between the transferred substrate and the previously laminated multilayer structure or Desorption between multilayer structures may occur due to a decrease in the bonding force between the multilayer structures.

Step (C) may be performed by stacking other multilayer structures at an angle of 0˚ to 90˚, preferably 85˚ to 90˚, with the multilayer structure formed at the top.

(D) manufacturing a catalyst for water electrolysis by heat treating the multilayer structure laminated on the substrate

The step (D) is a step of doping antimony into tin oxide and strengthening the bonding force between the multilayer structures, and is performed at 500 to 900 ° C., preferably 600 to 800 ° C. for 10 minutes to 3 hours, preferably 1 hour to 2 hours. It may be performed for 30 minutes. If the time and temperature are below the above lower limit, antimony may not be sufficiently doped into the tin oxide, which may significantly lower the electrical conductivity or the bonding strength between the multilayer structures may not be sufficient. Conversely, if the time and temperature exceed the above upper limit, the shape of the three-dimensional nanostructure may be deformed. It can rise or fall.

The antimony-doped tin oxide layer may be doped with 5 to 15 wt% of antimony, preferably 7 to 12 wt%, based on 100 wt% of the antimony-doped tin oxide.

The antimony-doped tin oxide layer may have a thickness of 10 to 50 nm, preferably 15 to 25 nm, and the iridium layer may have a thickness of 0.5 to 2 nm.

In particular, although not explicitly described in the following examples or comparative examples, in the method for producing a catalyst for water electrolysis of the present invention, a catalyst for water electrolysis is prepared by varying the following conditions, and a water electrolysis reaction is performed 200 times for a battery using the same. was performed and its form was confirmed through a scanning electron microscope.

As a result, unlike other conditions, when all of the following conditions were satisfied, the current density was maintained constant during 200 water electrolysis reactions, no entanglement or separation between nanowire complexes occurred, and no loss of iridium was observed. It was confirmed that durability was excellent.

① The material of the polymer mold is polymethyl methacrylate (PMMA),

② The constant interval is 300 to 600 nm,

③ The step (A2) is performed by coating a polymer solution containing 3 to 5% by weight of the polymer,

④ The step (A3) involves attaching an adhesive film to the polymer layer and then separating the polymer layer from the master mold,

⑤ The deposition in step (B) is performed using electron beam deposition,

⑥ The step (B) includes (B1) depositing iridium on the plurality of reliefs to form an iridium layer; (B2) forming a tin oxide layer and an antimony layer on the iridium layer, alternately depositing the tin oxide and antimony so that the tin oxide layer is formed on both sides of the antimony layer; and (B3) depositing iridium on the tin oxide layer formed at the top in step (B2),

⑦ The rate at which the iridium is deposited in the step (B1) and the step (B3) is 0.1 to 0.5 Å/s, and the rate at which the tin oxide and antimony are deposited in the step (B2) is 1.0 to 2.0 Å/s. s,

⑧ Before step (C), exposing the adhesive film to organic solvent vapor at 50 to 60°C for 10 to 20 seconds,

⑨ The step (C) is performed by stacking other multilayer structures at an angle of 85 to 90 degrees with the uppermost multilayer structure,

⑩ The step (D) is performed at 600 to 800 ° C. for 1 hour to 2 hours and 30 minutes,

⑪ The antimony-doped tin oxide layer is doped with 7 to 12% by weight of antimony based on 100% by weight of the antimony-doped tin oxide,

⑫ The thickness of the antimony-doped tin oxide layer may be 15 to 25 nm, and the thickness of the iridium layer may be 0.5 to 2 nm.

However, if any of the above conditions were not met, the nanowire composites became entangled or separated after 200 water electrolysis reactions, resulting in a significant decrease in water electrolysis performance, and loss of iridium was observed.

Hereinafter, the present invention will be described in more detail through examples, etc., but the scope and content of the present invention should not be construed as being reduced or limited by the examples below. In addition, based on the disclosure of the present invention, including the following examples, it is clear that a person skilled in the art can easily implement the present invention for which no specific experimental results have been presented.

Preparation Example 1. Antimony-doped tin oxide nanowire composite (ATO/NW)

Figure 2 is a schematic diagram showing the manufacturing method of the antimony-doped tin oxide nanowire composite prepared in the production example of the present invention. With reference to this, the manufacturing method of the antimony-doped tin oxide nanowire composite will be described.

A master mold with irregularities in which straight pillars with a constant width are arranged at 400 nm intervals is manufactured. Polydimethylsiloxane (PDMS) solution (2 wt%) purchased from Polymer Source Inc. was spin-coated on the upper surface of the master mold and heat treated at 150°C for 1 hour. Afterwards, the remaining PDMS polymer that did not stick to the master mold was removed by washing with heptane. A polymethyl methacrylate (PMMA) (4 wt%, volume ratio toluene:acetone:heptane = 4.5:4.5:1, Sigma-Aldrich Inc.) solution was spin-coated on the master mold. After attaching an adhesive polyimide tape (3M Inc.) to the upper surface of the PMMA, the PMMA was removed from the master mold to prepare a PMMA model in which the reverse image of the same shape as the pattern of the master mold was replicated.

Tin oxide, antimony, and tin oxide were sequentially deposited (deposition rate = 1.2 Å/s) following the pattern of the PMMA model through oblique deposition (deposition angle = 80˚) using an E-beam evaporator. As a result, a nanowire with an interlayer structure in which tin oxide, antimony, and tin oxide were sequentially deposited along the irregularities of the PMMA thin film was formed. To weaken the adhesion between the polyimide tape and PMMA, the interlayer structure of tin oxide, antimony, and tin oxide deposited on PMMA was exposed to organic solvent vapor (volume ratio acetone:heptane = 1:1) at 55°C for 15 seconds. By attaching it to the target substrate and removing the PMMA model by washing it with toluene, a nanowire with an interlayer structure of aligned tin oxide, antimony, and tin oxide was produced. Next, the nanowires forming the interlayer structure were stacked four times at a 90° angle with other nanowires adjacent to each other on the substrate. Next, a high-temperature heat treatment process was performed to allow the antimony to sufficiently diffuse into the tin oxide layers located above and below the tin oxide, antimony, and tin oxide interlayer structure. The high-temperature heat treatment process was maintained at a temperature of 700° C. for 2 hours in an argon atmosphere.

In Preparation Example 1, the antimony was doped at 10% by weight based on 100% by weight of the antimony-doped tin oxide, and the thickness of the antimony-doped tin oxide layer was 20 nm.

Example 1. Ir-ATO/NW

Instead of depositing tin oxide, antimony, and tin oxide sequentially, iridium, tin oxide, antimony, tin oxide, and iridium were deposited sequentially following the pattern of the PMMA model using an E-beam evaporator (iridium deposition rate = 0.2). Å/s, tin oxide and antimony deposition rate = 1.2 Å/s) A catalyst for water electrolysis was prepared in the same manner as in Example 1, except that a multilayer structure was prepared (stacking angle = 90°, 4 times stacking). .

In Example 1, the antimony was doped at 10% by weight based on 100% by weight of the antimony-doped tin oxide, the thickness of the antimony-doped tin oxide layer of the water electrolysis catalyst was 20 nm, and the thickness of the iridium layer was is 1 It was nm.

Comparative Example 1. Ir/C

The commercial Ir/C catalyst was prepared as a slurry using Ir/C 20% (Premetek Inc.). The slurry was prepared by mixing 10 mg Ir/C, 0.4 mL DI water, 0.568 mL IPA, and 0.032 mL of Nafion solution (5 wt%, Sigma Aldrich) and sonicating for 30 minutes.

Comparative Example 2. IrO ₂

The commercial IrO ₂ catalyst was prepared as a slurry using IrO ₂ (Premetek Inc.). The slurry was prepared by mixing 2 mg IrO2, 0.4 mL DI water, 0.568 mL IPA, and 0.032 mL Nafion solution (5 wt%, Sigma Aldrich) and sonicating for 30 minutes.

Comparative Example 3. Ir/C/NW

Instead of depositing iridium, tin oxide, antimony, tin oxide, and iridium sequentially, iridium, graphite carbon, and iridium were deposited along the pattern of the PMMA model through oblique deposition (deposition angle = 80°) using an E-beam evaporator. A catalyst for water electrolysis was prepared in the same manner as in Example 1, except that it was sequentially deposited (iridium deposition rate = 0.2 Å/s, graphite carbon deposition rate = 1.0 Å/s).

Experimental Example 1. Shape analysis of catalyst for water electrolysis

Figure 3 is a scanning electron microscope (SEM) image of the top and cross sections of the antimony-doped tin oxide nanowire composite prepared in the preparation example of the present invention. Referring to this, the nanowires are aligned parallel to each other and spaced at regular intervals. You can check the shape.

Figure 4 shows (a) a transmission electron microscope (TEM) image and (b) an energy dispersive analysis (EDS) image of the upper surface of a catalyst for water electrolysis manufactured according to an embodiment of the present invention. Referring to these, the nanowires are constant. It can be seen that the nanowire complexes are stacked at intervals and that iridium, antimony, and tin are uniformly distributed along the nanowires.

Experimental Example 2. X-ray diffraction (XRD) analysis X-ray photoelectron spectroscopy analysis

Figure 5 shows an The nanowire showed amorphous properties, but after heat treatment, it showed crystalline properties and it was confirmed that antimony was doped into tin oxide.

Figure 6 shows the X-ray photoelectron spectroscopy (XPS) pattern of the antimony-doped tin oxide nanowire composite prepared in the preparation example of the present invention immediately after deposition and after heat treatment. Referring to FIG. 6, the 3d peak of antimony before heat treatment shifts to a higher binding energy after heat treatment, confirming that antimony is well doped into the tin oxide layer.

Experimental Example 3. Water electrolysis cell performance analysis

The performance and degradation characteristics of water electrolysis cells using the water electrolysis catalysts prepared in Example 1 and Comparative Examples 1 and 2 were measured and shown in Figures 7 and 8.

The water electrolysis performance analysis of the prepared water electrolysis catalyst was performed using glassy carbon as a working electrode, a platinum wire as a counter electrode, and a reversible hydrogen electrode (RHE). was used as a reference electrode and 0.05 MH ₂ SO ₄ (98%, Sigma Aldrich) was used as an electrolyte. During the evaluation of catalyst performance for water electrolysis, the working electrode was rotated at a speed of 1600 to 2500 rpm through a modulated speed rotator (Pine Instruments). In addition, all water electrolysis catalyst performance evaluations were measured using Interface 1000E potentiostat (Garmry) equipment. The activity of the water electrolysis catalyst was measured through a linear polarization curve measured at a rate of 5 mV/s in the range of 1.2-1.7 V. The activity-to-mass activity of the water electrolysis catalyst was calculated by dividing the current density value at 1.55 V by the total mass of the catalyst used in the measuring working electrode. The deterioration characteristics of the water electrolysis catalyst were measured by continuously obtaining an electrochemical voltage at which the water electrolysis catalyst showed a current density of 1 mA/cm ² .

Figure 7 shows (a) oxygen evolution reaction (OER) performance of a battery using the water electrolysis catalyst prepared in Example 1 and Comparative Examples 1 to 3 of the present invention, and (b) a graph of activity versus mass analysis.

Referring to FIG. 7, it can be seen that as a result of the hydrogen generation reaction, the water electrolysis catalyst of the above example exhibits excellent catalytic activity by significantly increasing mass activity and current density compared to the catalysts prepared in Comparative Examples 1 to 3.

Figure 8 is a graph showing the results of evaluation of the deterioration characteristics of a battery using the water electrolysis catalyst prepared in Example 1 and Comparative Examples 1 to 3 of the present invention. With reference to this, as a result of the evaluation of the stability of the oxygen generation reaction, the water electrolyzer according to the present invention It can be seen that the dissolved catalyst showed a lower overvoltage than the catalyst prepared in Comparative Examples 1 to 3, showing a marked improvement in stability.

Claims (21)

delete delete delete delete delete delete delete (A) preparing a polymer mold having irregularities on the surface including a plurality of reliefs spaced parallel to each other at regular intervals;
(B) manufacturing a multilayer structure by depositing iridium, tin oxide, and antimony on the plurality of reliefs;
(C) stacking the multilayer structure 4 to 40 times on a substrate; and
(D) manufacturing a catalyst for water electrolysis by heat treating the multilayer structure laminated on the substrate;
The step (A) includes (A1) forming a polydimethylsiloxane (PDMS) coating layer on a master mold having irregularities including a plurality of negative engravings corresponding to the plurality of positive engravings; (A2) forming a polymer layer on the polydimethylsiloxane coating layer; and (A3) manufacturing a polymer mold by separating the master mold and the polymer layer.
The catalyst for water electrolysis is a stack of a plurality of nanowire composites in which a plurality of nanowires are arranged in parallel with each other and spaced at regular intervals,
The nanowire includes a tin oxide layer and an iridium layer doped with antimony,
The material of the polymer mold is polymethyl methacrylate (PMMA),
The regular interval is 300 to 600 nm,
The step (A2) is performed by coating a polymer solution containing 3 to 5% by weight of the polymer,
The step (A3) involves attaching an adhesive film to the polymer layer and then separating the polymer layer from the master mold,
The deposition in step (B) is performed using electron beam deposition,
The step (B) includes (B1) depositing iridium on the plurality of reliefs to form an iridium layer; (B2) forming a tin oxide layer and an antimony layer on the iridium layer, alternately depositing the tin oxide and antimony so that the tin oxide layer is formed on both sides of the antimony layer; and (B3) depositing iridium on the tin oxide layer formed at the top in step (B2),
The rate at which the iridium is deposited in the step (B1) and the step (B3) is 0.1 to 0.5 Å/s, and the rate at which the tin oxide and antimony are deposited in the step (B2) is 1.0 to 2.0 Å/s. ego,
It further includes exposing the adhesive film to organic solvent vapor at 50 to 60° C. for 10 to 20 seconds before step (C),
Step (C) is performed by stacking other multilayer structures at an angle of 85 to 90 degrees with the uppermost multilayer structure,
Step (D) is performed at 600 to 800 ° C. for 1 hour to 2 hours and 30 minutes,
The antimony-doped tin oxide layer is doped with 7 to 12% by weight of antimony based on 100% by weight of the antimony-doped tin oxide,
A method for producing a catalyst for water electrolysis, wherein the antimony-doped tin oxide layer has a thickness of 15 to 25 nm, and the iridium layer has a thickness of 0.5 to 2 nm. delete delete delete delete delete delete delete delete delete delete delete delete delete