Catalyst electrode for ammonia water electrolysis having improved durability and catalyst activity due to ultrasonic treatment and manufacturing method thereof

Abstract

Disclosed are a catalyst electrode for ammonia water electrolysis and a manufacturing method thereof, the durability and catalytic activity of the catalyst electrode being improved by synthesizing platinum catalyst seeds through an ultrasonic treatment of a specific duration and inhibiting poisoning of a platinum catalyst by nickel hydroxide formed on the surface of a nickel support.

Description

A catalyst electrode for ammonia water electrolysis with improved durability and catalytic activity through ultrasonic treatment and a method for manufacturing the same

[0001] The present invention relates to a catalyst electrode for ammonia electrolysis and a method for manufacturing the same, and more particularly, to a catalyst electrode for ammonia electrolysis with improved durability and catalytic activity through ultrasonic treatment and a method for manufacturing the same.

[0002] This application claims priority to and the benefit of Republic of Korea Patent Application No. 10-2023-0172760, filed December 1, 2023, which is incorporated herein by reference in its entirety.

[0003] Ammonia, the nitrogen compound with the lowest oxidation state, can be generated directly in various industrial processes or as a result of the nitrogen cycle during the treatment of nitrate nitrogen compounds. Ammonia can be treated through degassing, biological decomposition, chlorination, and electrochemical decomposition. Among these, electrochemical oxidation has recently attracted significant attention due to its economic feasibility, rapid and simple operation, and minimal secondary emissions.

[0004] Existing technologies for hydrogen production using ammonia include thermal decomposition of ammonia and electrolytic decomposition of aqueous ammonia solutions. Thermal decomposition of ammonia simultaneously produces nitrogen and hydrogen, requiring expensive palladium membranes to separate high-purity hydrogen. This limits productivity and economic feasibility. Furthermore, little research has been conducted on electrolytic decomposition of aqueous ammonia solutions, particularly on the development of electrodes suitable for the electrolysis of aqueous ammonia solutions. Therefore, the development of electrodes effective for the electrolysis reaction of aqueous ammonia solutions is necessary.

[0005] Meanwhile, unlike water electrolysis, which theoretically requires 1.23 V, ammonia electrolysis, which requires only 0.06 V, is highly promising as a source of hydrogen fuel. Among the widely used catalysts, transition metal catalysts, excluding precious metals like platinum and iridium, suffer from extremely high overvoltages, hindering widespread use. However, platinum-based catalyst materials face challenges due to their high cost, making them difficult to achieve economic feasibility.

[0006] In addition, the ammonia electrolysis reaction has a problem in that the electrode activity is deactivated within minutes to hours due to poisoning by nitrogen oxides, which are reactants or intermediate products, thereby reducing the durability of the catalyst electrode.

[0007] Korean Patent Publication No. 10-2022-0068566 (May 26, 2022) relates to a hydrogen production device using an aqueous ammonia solution. It manufactures and uses an electrode in which platinum is deposited on a nickel metal foam, but does not mention a technology for improving the durability and activity of the catalyst electrode through ultrasonic treatment.

[0008] In addition, Yejin Yang et al. (JOURNAL OF MATERIALS CHEMISTRY A, v.9, no.19, May 2021, pp.11571-11579) disclosed a technology for using platinum as an ammonia oxidation catalyst by electrochemically depositing it on carbon paper using a potential cycling method, but they did not mention a technology for improving the durability and activity of the catalyst electrode through ultrasonic treatment.

[0009] The present invention provides an ammonia-water electrolysis catalyst electrode having improved durability and activity, and a method for effectively manufacturing the same, by removing an oxide layer on a support surface and inducing hydroxide formation while simultaneously forming a metal catalyst seed in the catalyst electrode for ammonia-water electrolysis.

[0010] In order to solve the above problem, the present invention provides a method for manufacturing a catalyst electrode for ammonia electrolysis, comprising the steps of: (A) ultrasonically treating a support in a solution containing a precursor of an active metal catalyst; and (B) electroplating the active metal catalyst on the surface of the support by applying voltage to the resultant product of step (A).

[0011] In addition, a method for manufacturing a catalyst electrode for ammonia electrolysis is provided, characterized in that the frequency of the ultrasonic waves in the step (A) is 10 to 130 kHz and the processing time is 10 seconds to 60 minutes.

[0012] In addition, the present invention provides a method for manufacturing a catalyst electrode for ammonia electrolysis, characterized in that the support comprises at least one material selected from the group consisting of nickel, iron, aluminum, and carbon, and the active metal catalyst is at least one material selected from the group consisting of platinum, iridium, rhodium, palladium, ruthenium, iron, nickel, and cobalt.

[0013] In addition, a method for manufacturing a catalyst electrode for ammonia electrolysis is provided, characterized in that an electrolyte is further added to the solution of step (A) and ultrasonic treatment is performed.

[0014] In addition, a method for manufacturing a catalyst electrode for ammonia electrolysis is provided, characterized in that the electrolyte is an acidic electrolyte.

[0015] In addition, the support includes nickel, the active metal catalyst is platinum, and the ammonia-water electrolysis catalyst electrode is characterized in that 20 to 60 wt% of the platinum is supported and 1 to 50 wt% of nickel hydroxide is included through the ultrasonic treatment, and a method for manufacturing a catalyst electrode for ammonia-water electrolysis is provided.

[0016] In order to solve the above-mentioned further problem, the present invention provides a catalyst electrode for ammonia electrolysis manufactured according to the above-mentioned method.

[0017] The present invention includes a step of placing a support in a precursor solution of an active metal and treating it with an ultrasonic disperser, wherein by treating the support with an ultrasonic disperser for a specific period of time, a hydroxide and a metal catalyst seed can be formed on the surface of the support, and durability is improved by suppressing a poisoning phenomenon by the formed hydroxide, and the amount of active metal deposition is improved by the formed metal catalyst seed, thereby providing an ammonia-water electrolysis catalyst electrode having improved ammonia-water electrolysis activity.

[0018] Figure 1 is a photograph showing the results of SEM analysis performed on a nickel support in Example 1 of the present invention.

[0019] Figure 2 is a photograph showing the results of SEM analysis performed on the nickel support in Comparative Example 1 of the present invention.

[0020] Figure 3 is a photograph showing the results of an SEM analysis performed on an ammonia water electrolysis catalyst electrode manufactured according to Example 1 of the present invention.

[0021] Figure 4 is a photograph showing the results of an SEM analysis performed on an ammonia water electrolysis catalyst electrode manufactured according to Comparative Example 1 of the present invention.

[0022] Figure 5 is a graph showing the results of measuring the platinum content of nickel supports in Example 1, Example 2, and Comparative Example 1 of the present invention.

[0023] Figure 6 is a graph showing the results of measuring the platinum content of a catalyst electrode for ammonia electrolysis manufactured according to Example 1, Example 2, and Comparative Example 1 of the present invention.

[0024] Figure 7 is a graph showing the results of analysis of surface chemical species and chemical bonding energy of an ammonia water electrolysis catalyst electrode manufactured according to Example 1 of the present invention.

[0025] Figure 8 is a graph showing the results of analysis of surface chemical species and chemical bonding energy of the nickel support in Comparative Example 1 of the present invention.

[0026] Figure 9 is a graph showing the results of analysis of surface chemical species and chemical bonding energy of an ammonia water electrolysis catalyst electrode manufactured according to Comparative Example 1 of the present invention.

[0027] Figure 10 is a graph showing the results of measuring ammonia oxidation characteristics using a catalyst electrode for ammonia electrolysis manufactured according to Example and Comparative Example 1 of the present invention.

[0028] Figure 11 is a graph showing the results of evaluating the electrochemical stability of a catalyst electrode for ammonia electrolysis manufactured according to Example and Comparative Example 1 of the present invention.

[0029] Hereinafter, the present invention will be described in detail through preferred embodiments. Prior to this, it should be noted that the terms and words used in this specification and claims should not be interpreted as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention, they should be interpreted as meanings and concepts that conform to the technical concept of the present invention. Therefore, the configuration of the embodiments described in this specification is only the most preferred embodiment of the present invention and does not represent the entire technical concept of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of filing this application.

[0030]

[0031] The present invention discloses a method for manufacturing a catalyst electrode for ammonia electrolysis, comprising the steps of: (A) ultrasonicating a support in a solution containing a precursor of an active metal catalyst; and (B) electroplating the active metal catalyst on the surface of the support by applying voltage to the resultant product of step (A).

[0032] The support may include at least one material selected from the group consisting of nickel, iron, aluminum, and carbon. The support serves as a substrate on which the active metal catalyst is formed, and nickel material may preferably be applied.

[0033] In the present invention, the shape of the support is not particularly limited, but may be in the shape of a foam, plate, fabric, foil, or felt, and preferably, it may be a metal foam support. When the support is a metal foam support, the stability of the electrode, the amount of catalyst supported, and the mobility of the electrolyte can be effectively increased, and the area of ​​the electrode catalyst particles, such as platinum particles, can be increased, thereby enhancing the electrode activity.

[0034] In one specific embodiment of the present invention, the metal foam support may be a nickel-based foam support. When the metal foam support is a nickel-based foam support, it can exhibit more stable support of active metal particles and effective catalytic activity of the active metal particles.

[0035] In the present invention, the active metal catalyst supported on the support is not particularly limited as long as it is a metal catalyst that functions as a catalyst for the oxidation reaction of ammonia electrolysis, but may be, for example, a catalyst characterized by at least one selected from the group consisting of noble metal catalysts such as platinum, iridium, rhodium, palladium, and ruthenium, and non-noble metal catalysts such as iron, nickel, and cobalt, and may preferably be a platinum catalyst in that it can promote the adsorption of ammonia in the ammonia oxidation reaction and greatly improve the electrolysis efficiency of the ammonia aqueous solution.

[0036] In addition, the precursor of the above active metal catalyst is a compound containing an active metal catalyst such as platinum, iridium, rhodium, palladium, ruthenium, iron, nickel, cobalt, etc. For example, chloroplatinic acid (H2PtCl6xH2O) can be used as a precursor for platinum active metal electroplating.

[0037] Additionally, the precursor of the active metal catalyst may be included in the solution in step (A) at a concentration of 0.5 to 20 mM, and preferably at a concentration of 1 to 5 mM. If the active metal catalyst precursor is outside the above concentration range, the support may be damaged.

[0038] In the present invention, the step of ultrasonicating the support in a solution containing a precursor of an active metal catalyst, wherein the ultrasonic treatment forms a hydroxide of the metal forming the support on the surface of the support, thereby preventing poisoning by nitrogen oxides generated in an ammonia-water electrolysis reaction, thereby improving durability, and also forming a seed of the active metal catalyst on the surface of the support, thereby improving the loading rate and catalytic activity of the active metal catalyst in a subsequent electroplating process, so that the step (A) serves to improve the durability and activity of the ammonia-water electrolysis catalyst electrode manufactured in the present invention.

[0039] The specific conditions for the above ultrasonic treatment are set to a frequency of 10 to 130 kHz and can be treated for 10 seconds to 60 minutes, and in terms of maximizing the durability and activity of the catalyst electrode for ammonia water electrolysis, it is preferably set to a frequency of 20 to 100 kHz and can be treated for 30 seconds to 40 minutes, and more preferably, it is set to a frequency of 30 to 80 kHz and can be treated for 1 minute to 20 minutes.

[0040] Meanwhile, if the frequency of the ultrasonic waves is outside the above range, the support may be damaged and its durability may be reduced, and if the ultrasonic treatment time is less than 10 seconds, the durability and activity enhancement effects may be minimal, and if the ultrasonic treatment time exceeds 60 minutes, the physical durability of the support may be reduced.

[0041] The above step (B) is a step of electroplating the active metal catalyst on the surface of the support by applying voltage to the result of the above step (A), so that even a small amount of the active metal catalyst is uniformly deposited over a wide surface area, thereby allowing an excellent ammonia oxidation reaction to occur at more active sites.

[0042] In the electroplating process in the above step (B), the voltage may be -1.0 to 1.0 V, preferably -0.5 to 0.8 V, more preferably -0.2 to 0.4 V, and the electroplating time may be 600 to 5400 seconds, preferably 1200 to 4800 seconds, and more preferably 2400 to 4200 seconds. In particular, when the electroplating time is less than 600 seconds, the amount of the deposited active metal catalyst may be insufficient, and when the electroplating time exceeds 5400 seconds, the amount of the deposited active metal catalyst may be excessive, which may reduce the economic feasibility of manufacturing the ammonia electrolysis catalyst electrode.

[0043] In addition, the present invention provides a method for manufacturing a catalyst electrode for ammonia electrolysis, characterized in that an electrolyte is additionally included in the solution of step (A) and ultrasonic treatment is performed.

[0044] The electrolyte is not particularly limited as long as it is a salt that allows the active metal catalyst to be transferred from the active metal catalyst precursor to the support and electroplated. For example, NaCl, KCl, KOH, LiCl, HClO4, HCl, H2SO4, etc. can be used. Considering the deposition efficiency, catalytic activity, and stability of the catalyst electrode, preferably, an acidic electrolyte such as HClO4, HCl, H2SO4, etc. can be used, and more preferably, HClO4 can be used.

[0045] The electrolyte may be included in the solution in step (A) at a concentration of 0.5 to 5000 mM, preferably at a concentration of 5 to 3000 mM, and more preferably at a concentration of 100 to 1000 mM. If the electrolyte is outside the concentration range, the amount of the metal catalyst supported may be insufficient or the support may be damaged.

[0046] In addition, according to one specific example of the present invention, a method for manufacturing an ammonia electrolysis catalyst electrode can be provided, characterized in that the support in the step (A) includes nickel, the surface of the ammonia electrolysis catalyst electrode includes 1 to 50 wt% of nickel hydroxide through the ultrasonic disperser treatment, the active metal catalyst electroplated in the step (B) uses platinum, and the platinum is supported in 20 to 60 wt% of the ammonia electrolysis catalyst electrode.

[0047] Meanwhile, if the nickel hydroxide content is outside the above range, the catalytic activity may be reduced, and if the platinum content is higher than the above range, the economic feasibility may be reduced.

[0048] In addition, it was confirmed through surface chemical species analysis of the test examples described below that the content of the nickel hydroxide can be improved to about 90% of the platinum content by the ultrasonic disperser treatment, and the nickel hydroxide can be included in the catalyst electrode at 1 to 50 wt%, and in terms of maximizing the durability and catalytic activity of the catalyst electrode, it can be preferably 10 to 45 wt%, and more preferably 30 to 45 wt%.

[0049] In addition, the present invention can provide an ammonia electrolysis catalyst electrode having improved durability and catalytic activity by being manufactured using the above manufacturing method.

[0050] That is, according to the present invention, before electroplating the active metal catalyst on the support, the support is treated with the ultrasonic disperser, and by performing ultrasonic treatment at a specific frequency and treatment time while the support is placed in a precursor solution of the active metal catalyst, a hydroxide and the active metal catalyst seed can be formed on the surface of the support, so that poisoning by nitrogen oxide is prevented through the hydroxide, thereby improving the durability of the electrode, and the active metal catalyst is electroplated more actively around the seed, thereby providing an ammonia electrolysis catalyst electrode having improved loading rate and catalytic activity of the active metal catalyst compared to the same electroplating process time.

[0051] Hereinafter, the present invention will be described in more detail through specific examples and comparative examples.

[0052]

[0053] Example 1

[0054] A nickel support (MTI Korea, nickel thickness 1600 μm, porosity 50-98%) measuring 1 cm in width and 1 cm in length was placed in a solution containing 2 mM of chloroplatinic acid (H2PtCl6xH2O), an active metal catalyst precursor, and 100 mM of electrolyte HClO4, and treated with an ultrasonic disperser (UCP-20, JEIO TECH), setting the frequency to 40 kHz, for 7 minutes.

[0055] After the above ultrasonic treatment, a voltage of -0.2 to 0.4 V was applied to the solution for 4200 seconds to deposit a platinum catalyst on the surface of a nickel support, thereby manufacturing a catalyst electrode for ammonia electrolysis.

[0056]

[0057] Example 2

[0058] An ammonia-water electrolysis catalyst electrode was manufactured in the same manner as in Example 1, except that the ultrasonic treatment was performed for 2 minutes.

[0059]

[0060] Example 3

[0061] An ammonia-water electrolysis catalyst electrode was manufactured in the same manner as in Example 1, except that the ultrasonic treatment was performed for 15 minutes.

[0062]

[0063] Example 4

[0064] A catalyst electrode for ammonia electrolysis was manufactured in the same manner as in Example 1, except that 0.05 M H2SO4 was used as the electrolyte in Example 1.

[0065]

[0066] Example 5

[0067] A catalyst electrode for ammonia electrolysis was manufactured in the same manner as in Example 1, except that 0.1 M KOH was used as the electrolyte.

[0068]

[0069] Comparative Example 1

[0070] An ammonia-water electrolysis catalyst electrode was manufactured in the same manner as in Example 1, except that ultrasonic treatment using an ultrasonic disperser was not performed in Example 1.

[0071]

[0072] Comparative Example 2

[0073] An ammonia-water electrolysis catalyst electrode was manufactured in the same manner as in Example 1, except that no electrolyte was added.

[0074]

[0075] Test Example 1

[0076] In order to confirm the change in the surface of the nickel support according to the ultrasonic treatment in the present invention, a scanning electron microscope (SEM) analysis was performed on the nickel support before electroplating in Example 1 and Comparative Example 1, and the results are shown in FIGS. 1 and 2.

[0077] Referring to FIGS. 1 and 2, it can be confirmed that platinum catalyst seeds are formed on the surface of the nickel support in Example 1 (see FIG. 1) where ultrasonic treatment was performed, unlike in Comparative Example 1 (see FIG. 2) where ultrasonic treatment was not performed.

[0078] In addition, in order to confirm the change in the surface of the ammonia electrolysis catalyst electrode according to the ultrasonic treatment in the present invention, SEM analysis was performed on the ammonia electrolysis catalyst electrode manufactured according to Example 1 and Comparative Example 1, and the results are shown in FIGS. 3 and 4.

[0079] Referring to FIGS. 3 and 4, the shape of the platinum catalyst electroplated on the surface of the ammonia-water electrolysis catalyst electrode manufactured according to Example 1 (see FIG. 3) was confirmed to be similar to the shape of the platinum catalyst electroplated on the surface of the ammonia-water electrolysis catalyst electrode manufactured according to Comparative Example 1 (see FIG. 4). This confirms that ultrasonic treatment does not affect the shape of the platinum catalyst during electroplating.

[0080]

[0081] Test Example 2

[0082] In order to confirm the change in platinum content of the nickel support according to ultrasonic treatment in the present invention, ICP (Inductively Coupled Plasma) analysis was performed on the nickel support before electroplating in Example 1, Example 2, and Comparative Example 1 to measure the platinum content, and the results are shown in Fig. 5.

[0083] Referring to Fig. 5, the nickel support in Comparative Example 1 had almost no platinum content detected, which is consistent with the results in Test Example 1, and it was confirmed that the platinum content of the nickel support in Example 1 was improved by 340% compared to Example 2.

[0084] This can be seen as a galvanic replacement reaction in which platinum, which has a high standard reduction potential compared to nickel, is reduced by ultrasonic treatment, and the platinum content on the surface of the nickel support increases as the ultrasonic treatment time increases.

[0085] In addition, in order to confirm the change in platinum content in the ammonia water electrolysis catalyst electrode according to the ultrasonic treatment in the present invention, ICP (Inductively Coupled Plasma) analysis was performed on the ammonia water electrolysis catalyst electrodes manufactured according to Example 1, Example 2, and Comparative Example 1 to measure the content of deposited platinum, and the results are shown in Fig. 6.

[0086] Referring to FIG. 6, it was confirmed that the platinum content of the ammonia-water electrolysis catalyst electrode manufactured according to Example 2 was improved by 140% compared to Comparative Example 1, and it was confirmed that the platinum content of the ammonia-water electrolysis catalyst electrode manufactured according to Example 1 was improved by 190% compared to Example 2.

[0087] Through this, it can be seen that the amount of platinum catalyst deposited during electroplating is proportional to the amount of platinum seeds formed by the ultrasonic treatment.

[0088]

[0089] Test Example 3

[0090] In order to confirm the factors for improving the durability of the ammonia electrolysis catalyst electrode according to the ultrasonic treatment in the present invention, the ammonia electrolysis catalyst electrode manufactured according to Example 1, the nickel support before electroplating in Comparative Example 1, and the ammonia electrolysis catalyst electrode manufactured according to Comparative Example 1 were analyzed for changes in the oxidation numbers of platinum and nickel on the surface using X-ray photoelectron spectroscopy, and the results are shown in FIGS. 7 to 9, respectively. In addition, the surface chemical species and chemical bonding energies corresponding to the peaks of each drawing in FIGS. 7 to 9 are shown in Tables 1 to 3 below.

[0091] Surface chemical species of the catalyst electrode according to Example 1 Chemical binding energy (eV) Ni(OH)2, 3p 3 / 268.08 Pt (Metal), 4f 7 / 271.44 Pt(OH)2, 4f 7 / 272.85 Pt (Metal), 4f 5 / 274.73 Pt(OH)2, 4f 5 / 276.1

[0092] Surface chemical species of nickel support in comparative example 1 Chemical binding energy (eV) Ni (Metal), 3p 3 / 266.06 NiO, 3p 3 / 267.64 Pt (Metal), 4f 7 / 271.3

[0093] Surface chemical species of the catalyst electrode according to Comparative Example 1 Chemical binding energy (eV) Ni(OH)2, 3p 3 / 267.96 Pt(Metal), 4f 7 / 271.57 Pt(OH)2, 4f 7 / 272.52 Pt(Metal), 4f 5 / 274.92 Pt(OH)2, 4f 5 / 276.19

[0094]

[0095] Referring to FIGS. 7 to 9 and Tables 1 to 3 above, the results of the surface chemical species analysis of the nickel support before electroplating in Comparative Example 1 (see FIG. 8 and Table 2) show peaks of 66.06 eV and 67.64 eV, which are chemical bonding energies corresponding to nickel metal (Ni, 3p 3 / 2) and nickel oxide (NiO, 3p 3 / 2), respectively, and the peak intensity of the platinum (Pt) metal phase was confirmed to be significantly lower at around 12% compared to nickel oxide.

[0096] Meanwhile, in the results of surface chemical species analysis of the ammonia water electrolysis catalyst electrode manufactured according to Comparative Example 1 (see Fig. 9 and Table 3), Pt 0 Wow Pt 2+It was confirmed that the peak of the chemical bonding energy corresponding to was high at the level of 1:0.03 (Pt:Ni(OH)2) compared to the peak of nickel hydroxide, and in the analysis results of the surface chemical species of the catalyst electrode for ammonia water electrolysis manufactured according to Example 1 (see Fig. 7 and Table 1), it was confirmed that the peak of nickel hydroxide (Ni(OH)2, 3p 3 / 2) corresponding to the chemical bonding energy of 68.08 eV increased, and specifically, it was confirmed that the peak ratio of nickel hydroxide to platinum metal on the surface of the catalyst electrode increased to 1:0.89 (Pt:Ni(OH)2).

[0097] Through this, it was found that the content of nickel hydroxide on the surface of the ammonia water electrolysis catalyst electrode increased according to the ultrasonic treatment in Example 1, and specifically, it was confirmed that the content of nickel hydroxide could be improved to about 90% of the platinum content.

[0098]

[0099] Test Example 4

[0100] In order to confirm the change in ammonia oxidation activity of the ammonia electrolysis catalyst electrode according to ultrasonic treatment in the present invention, the ammonia oxidation characteristics were measured for the ammonia electrolysis catalyst electrodes manufactured according to Examples 1 to 3 and Comparative Example 1, and the results are shown in Fig. 10. All electrochemical measurements for ammonia oxidation were performed using an electrochemical workstation (Zive, Wonah Tech). Specifically, the electrolyte was 1 M NH4OH / 5 M KOH, and the electrochemical tests were performed in a three-electrode system in a sealed glass beaker without a membrane (to prevent evaporation of ammonia), using a Hg / HgO electrode (filling solution: 1.0 M KOH) and a Pt mesh as the reference and reference electrodes, respectively. The cyclic voltammetry (CV) curves of the catalysts were obtained from -0.15 to 1.2 V vs. RHE at a scan rate of 20 mV / s. Additionally, all potentials measured for Hg / HgO using Pt mesh as electrode and Hg / HgO as reference electrode in a hydrogen atmosphere were converted to the RHE (reversible hydrogen electrode) scale as shown in Equation 1 below.

[0101] [Mathematical Formula 1]

[0102] V RHE = V Hg / HgO + 0.97 (experimental measurement)

[0103] Referring to Figure 10, the ammonia oxidation catalyst performance is 510 mA / cm for the ammonia water electrolysis catalyst electrode manufactured according to Comparative Example 1. 2 , the ammonia water electrolysis catalyst electrode manufactured according to Example 3 was 600 mA / cm 2 , the ammonia water electrolysis catalyst electrode manufactured according to Example 2 was 650 mA / cm 2 , the ammonia water electrolysis catalyst electrode manufactured according to Example 1 was 770 mA / cm 2, it can be confirmed that the trend of the ammonia oxidation catalyst performance increases in the order of Comparative Example 1, Example 3, Example 2, and Example 1.

[0104] Through this, it can be seen that in the section where the ultrasonic treatment time is less than 7 minutes, the activity of the ammonia oxidation reaction increases as the ultrasonic treatment time increases, but when the ultrasonic treatment time exceeds 7 minutes, the activity of the ammonia oxidation reaction decreases.

[0105]

[0106] Test Example 5

[0107] In order to confirm the change in stability of the ammonia electrolysis catalyst electrode according to ultrasonic treatment in the present invention, the electrochemical stability of the ammonia electrolysis catalyst electrodes manufactured according to Examples 1 to 3 and Comparative Example 1 was evaluated under the following conditions, and the results are shown in Fig. 11.

[0108] [Evaluation Conditions]

[0109] - Use 1 M NH4OH / 5 M KOH electrolyte, stirring at 200 rpm.

[0110] - 50 mA / cm 2 The constant current test was conducted at room temperature, and the time for water oxidation reaction to occur due to catalyst poisoning was measured.

[0111] Referring to FIG. 11, the electrochemical stability of the catalyst electrode was confirmed as 5 hours for the ammonia electrolysis catalyst electrode manufactured according to Comparative Example 1, 13 hours for the ammonia electrolysis catalyst electrode manufactured according to Example 2, 44 hours for the ammonia electrolysis catalyst electrode manufactured according to Example 3, and 48 hours for the ammonia electrolysis catalyst electrode manufactured according to Example 1. In particular, the ammonia electrolysis catalyst electrode manufactured according to Example 1 showed electrochemical stability that was 9.6 times improved compared to Comparative Example 1.

[0112] Meanwhile, in the case of the ammonia water electrolysis catalyst electrode having a specific ultrasonic treatment time in the present invention (Example 1), it shows a remarkably improved electrochemical stability compared to the increase rate of the platinum catalyst content, and the content of nickel hydroxide is increased on the surface of the catalyst electrode. In summary of these test results, it can be seen that the ammonia water electrolysis catalyst electrode manufactured by the method according to the present invention is sonicated for a specific time as described above, thereby forming hydroxide on the surface of the support, and thus preventing poisoning by nitrogen oxides, thereby improving electrochemical stability and durability.

[0113]

[0114] Test Example 6

[0115] In order to confirm the change in ammonia oxidation activity and stability of the catalyst electrode according to the pH of the electrolyte in the present invention, the ammonia oxidation characteristics and electrochemical stability of the catalyst electrode for ammonia water electrolysis manufactured according to Examples 4, 5, and Comparative Example 2 were evaluated in the same manner as in Test Examples 4 and 5, and the results are shown in Table 4 below.

[0116] Classification Example 4 Example 5 Comparative Example 2 Ammonia water oxidation reaction peak current density 770 mA 540 mA 510 mAStability evaluation > 48 hrs. < 15 hrs. < 5 hrs.

[0117]

[0118] Referring to Table 4, it was confirmed that the ammonia oxidation activity and electrochemical stability were significantly improved in the ammonia electrolysis catalyst electrode (Example 4) using an acidic electrolyte compared to the ammonia electrolysis catalyst electrode (Example 5) using a basic electrolyte and the ammonia electrolysis catalyst electrode (Comparative Example 2) using no electrolyte.

[0119]

[0120] The preferred embodiments of the present invention have been described in detail above. The description of the present invention is provided for illustrative purposes only, and those skilled in the art will readily appreciate that other specific modifications can be readily made without altering the technical spirit or essential features of the present invention.

[0121] Accordingly, the scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modifications derived from the meaning, scope and equivalent concepts of the claims should be interpreted as being included in the scope of the present invention.

Claims

1. (A) a step of sonicating the support in a solution containing a precursor of an active metal catalyst; and (B) a step of electroplating the active metal catalyst on the surface of the support by applying voltage to the resultant product of step (A); A method for manufacturing a catalyst electrode for ammonia water electrolysis comprising:

2. In paragraph 1, A method for manufacturing a catalyst electrode for ammonia-water electrolysis, characterized in that in the step (A), the frequency of the ultrasonic waves is 10 to 130 kHz and the processing time is 10 seconds to 60 minutes.

3. In paragraph 1, The support comprises at least one material selected from the group consisting of nickel, iron, aluminum and carbon, A method for manufacturing a catalyst electrode for ammonia-water electrolysis, characterized in that the active metal catalyst is at least one selected from the group consisting of platinum, iridium, rhodium, palladium, ruthenium, iron, nickel, and cobalt.

4. In paragraph 1, A method for manufacturing a catalyst electrode for ammonia-water electrolysis, characterized in that the solution of step (A) is further treated with ultrasonic waves by adding an electrolyte.

5. In paragraph 4, A method for manufacturing a catalyst electrode for ammonia-water electrolysis, characterized in that the electrolyte is an acidic electrolyte.

6. In paragraph 1, The above support comprises nickel, The above active metal catalyst is platinum, A method for manufacturing an ammonia-water electrolysis catalyst electrode, characterized in that the ammonia-water electrolysis catalyst electrode is supported with 20 to 60 wt% of platinum and contains 1 to 50 wt% of nickel hydroxide through the above ultrasonic treatment.

7. A catalyst electrode for ammonia electrolysis manufactured according to any one of claims 1 to 6.

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