JP6515509B2 - ELECTRODE FOR HYDROGEN GENERATION, METHOD FOR PRODUCING THE SAME, AND ELECTROLYTIC METHOD USING THE SAME - Google Patents

Description

  The present invention relates to an electrode for hydrogen generation used for electrolysis of water or electrolysis of an aqueous solution of an alkali metal chloride such as sodium chloride, a method for producing the same, and an electrolysis method using the same.

  The water or alkali metal chloride aqueous solution electrolysis industry is a power-intensive industry, and various technological developments are being carried out for energy saving. The means of energy saving is to substantially reduce the electrolytic voltage composed of theoretical decomposition voltage, liquid resistance, diaphragm resistance, anodic overvoltage, cathodic overvoltage and the like. In particular, with regard to the reduction of the overvoltage, many researches and developments have been made on the improvement since the overvoltage value depends on the catalyst material of the electrode and the morphology of the electrode surface. Ion Exchange Membrane Method In salt electrolysis, research and development has been actively carried out to reduce anodic overvoltage, and as a result, a dimensionally stable electrode having a low anodic overvoltage and excellent durability [for example, DSE electrode manufactured by Permerek Electrodes ( ] Has been completed, and has already been used in the field of electrolytic industry, including the salt electrolytic industry.

  On the other hand, many proposals have been made regarding a hydrogen generation electrode for reducing cathodic overvoltage, so-called active cathode. Generally, the means for lowering the hydrogen overpotential is to improve the activity of the supported catalyst and increase the reaction specific surface area, and to improve the activity, metal mixtures of specific compositions, metal alloys, metal oxides or the like on conductive substrates The loading of a highly active catalyst composed of these mixtures and the increase in specific surface area are improved by the loading method, and the main loading method is electroplating that deposits catalyst components from a bath in which catalyst components and metal salts are dissolved. Method, dispersion plating method in which catalyst component is electrophoresed from a bath in which catalyst material is dispersed in metal salt solution, thermal spraying method in which catalyst material in molten state is directly sprayed on substrate, metal salt solution etc. is applied and fired Thermal decomposition methods.

  Conventionally, as an electrode of hydrogen overpotential lower than about 400 mV of hydrogen of iron cathode, for example, in combination with nickel, iron, cobalt, indium, amino acid, carboxylic acid, amine on conductive substrate surface by electroplating method The thing which carry | supported the substance containing organic compounds, such as, is disclosed (patent document 1). However, since it is necessary to make the support very thick, deformation of the electrode due to plating stress and peeling of the support are likely to occur, and since the activity of these base metals is low, the activity is improved by alloying the base metal. Alone was not enough to reduce the hydrogen overvoltage.

  In addition, although an alloy layer comprising nickel and molybdenum is supported by the arc ion plating method (Patent Document 2), although the initial hydrogen overvoltage is sufficiently low, the hydrogen overvoltage rises in long-term electrolytic operation, so-called durability There was a problem.

  On the other hand, an electrode for hydrogen generation is disclosed which is composed of a ternary alloy selected from nickel and / or cobalt, a component selected from aluminum, zinc, magnesium, silicon, and a noble metal such as platinum (Patent Document 3). In this electrode, the main point is to use Raney-type nickel and / or Raney-type cobalt catalyst as an electrode for hydrogen generation by eluting and removing components selected from aluminum, zinc, magnesium and silicon from the alloy consisting of the three components. In addition, by adding a trace amount of a precious metal component in a molar ratio of less than 0.4, durability can be improved by preventing deterioration of electrode activity due to deterioration of nickel and / or cobalt to nickel hydroxide or cobalt hydroxide. It is intended. However, since this electrode reduces the hydrogen overpotential by increasing the specific surface area of nickel and / or cobalt, a process for removing the component from the catalyst is necessary, and the thickness of the support is increased to several tens to several hundreds of μm. The problem is that the cost of production is very high. In addition, it is described in patent document 3 that there is no reduction effect of hydrogen generation | occurence | production overvoltage, even if a noble metal component is 0.4 or more by molar ratio.

Besides, it has been conventionally proposed to use a mixture of a platinum group metal oxide and an oxide such as Ni or a composite oxide. For example, Patent Document 4 describes a condition sufficient for oxidizing a metal compound after applying and drying a mixed solution of a platinum group metal compound and a metal compound such as Ni, ie, in an oxidizing gas such as air or oxygen There has been proposed a method of producing an electrode comprising a mixed oxide of a platinum group metal oxide and a Ni oxide or the like, or a composite oxide, by heat treatment at a high temperature. In Example 3 of Patent Document 4, a mixed solution of chloroplatinic acid, nickel chloride and ruthenium chloride is coated on a nickel base, dried, and then pyrolyzed at 470 to 480 ° C. to manufacture platinum, nickel and ruthenium. An oxide-coated electrode for hydrogen generation is disclosed, and the first week overpotential is sufficiently satisfied with 42 mV when converted from the actual absolute repeatability voltage based on the thermodynamic calculation described in Patent Document 4 to an overvoltage. Although it can be done, the overvoltage rises with the progress of electrolysis, and the hydrogen generation overpotential at the 6th week is 87mV and 97mV after the 11th week. Therefore, when used at a current density of 5 kA / m ² or more, the overvoltage is expected to be at least 100 mV at least, and there is a problem to be solved.

  On the other hand, in addition to the above, an electrode for hydrogen generation in which a plurality of noble metal elements and base metal elements are combined is conventionally proposed. For example, Patent Document 5 includes a noble metal deposit consisting of one kind of noble metal or a mixture or alloy of two or more kinds of noble metals, and containing one kind or two or more kinds of base metals such as Ni in the noble metal deposit. An electrode for hydrogen generation has been proposed in which a deposit is deposited on a conductive substrate such as Ni. However, it is known that these hydrogen generation electrodes have a problem that they are easily poisoned by impurities such as iron in the electrolytic solution (Patent Document 6).

  Thus, although an electrode for hydrogen generation having a low hydrogen overvoltage formed by supporting a noble metal is conventionally proposed, the electrode for hydrogen generation formed by supporting platinum corresponds to a small amount of iron ions present in the electrolyte. On the other hand, the hydrogen overpotential is susceptible to poisoning and the hydrogen overpotential is increased even if the iron ion concentration is 1 ppm or less, so that the alkali metal chloride aqueous solution which is easily mixed with iron ions in the electrolytic solution Further improvements in use are being considered.

Therefore, extensive studies have been made for the purpose of preventing poisoning by iron ions in the electrolyte, and various proposals have been made. For example, when a hydrogen generation cathode having a low hydrogen overpotential is used for electrolysis of an aqueous alkali metal chloride solution, the relationship between iron deposition on the cathode and iron ions in the catholyte is examined, and the cathode liquid is contained in the catholyte. It is found that precipitation of iron can be prevented when the iron ion concentration of the catalyst is 0.5 ppm or less, and a low hydrogen overvoltage cathode is used, and the iron ion concentration in the catholyte is maintained at 0.5 ppm or less. A method of electrolysis of an aqueous alkali metal chloride solution to be electrolyzed has been proposed (Patent Document 6). According to this invention, it has become possible to use an electrode for hydrogen generation, which is susceptible to poisoning to iron ions, in the electrolysis industry and the like of an aqueous solution of alkali metal chloride. However, in order to implement the proposal of Patent Document 6, a material such as high Ni-based stainless steel or Ni is used for at least the positively polarized portion of the portion in contact with the catholyte, or a corrosion current is supplied at the time of stopping There is a need and an issue to be improved from an economic point of view.

  In addition, a method of removing iron from a hydrogen generation electrode whose overvoltage has been raised by iron ions has been studied, and proposals have been made to remove and reuse iron from a hydrogen generation electrode whose hydrogen overvoltage has deteriorated due to precipitation of iron. . For example, a method has been proposed for removing iron deposited on the surface of the cathode, which comprises contacting with the liquid medium which reacts with the iron deposited on the surface and solubilizes it (Patent Document 7). By using this method, it has become possible to reuse the hydrogen generation electrode whose overvoltage has been raised by iron ions, but in order to carry out the proposal, it is necessary to frequently stop the electrolysis, and it will be continuous for a long time Can not operate stably. Therefore, in this case also, there is a problem to be improved from the economic point of view.

  Further, attempts have been widely made in the past to impart characteristics in which iron ions are difficult to attach to the hydrogen generation electrode itself, or the performance does not deteriorate even if the iron ions adhere to the electrode. For example, a hydrogen generating electrode has been proposed in which a catalyst containing at least one of platinum and ruthenium and gold or silver, or a catalyst further containing particles of an organic polymer is supported on a conductive substrate (Patent Document 8). The electrode for hydrogen generation has a very small increase in overvoltage even when iron ions are present in the catholyte, and it is certainly excellent in that it can reduce the amount of energy used for electrolysis of an aqueous solution of alkali metal chloride. And an electrode for hydrogen generation. However, platinum, gold and silver are all expensive materials, and when including polytetrafluoroethylene, they become much more expensive. Therefore, there is still a problem to be improved from the economic point of view.

  On the other hand, an electrode for hydrogen generation using a catalyst consisting of platinum and cerium has been proposed (Patent Document 9). The electrode for hydrogen generation which consists of the catalyst of the said platinum and cerium has a low overvoltage, the influence by iron ion is suppressed, and it shows the outstanding performance as an electrode for hydrogen generation for electrolysis of alkali metal chloride aqueous solution. Furthermore, in addition to platinum and cerium, an electrode for hydrogen generation using a catalyst layer essentially comprising four components of lanthanum and ruthenium has been proposed (Patent Documents 10 and 11). The hydrogen generation electrode using a catalyst consisting of platinum and cerium, lanthanum, and ruthenium has a hydrogen overpotential that is equivalent to or reduced by 5 mV as compared with a hydrogen generation electrode using a catalyst consisting only of platinum and cerium; While stopping the electrolysis for 1 hour a day, the hydrogen overvoltage does not change even in continuous electrolysis for 10 days, there is no exhaustion of the catalyst, and there is an excellent performance that there is no deposit on the electrode surface.

  In addition, as a cathode for hydrogen generation having ruthenium in the catalyst layer, a catalyst layer (patent document 12) prepared using ruthenium nitrate and a carboxylate of lanthanum as a coating material, a mixture of a ruthenium compound and a cerium compound in the presence of oxalic acid A cathode for hydrogen generation (Patent Document 13) containing a composition obtained by thermal decomposition under the following conditions: Electroplating in a nickel plating bath containing ruthenium oxide to form a plating layer of nickel and ruthenium oxide; There is an electrode for hydrogen generation (Patent Document 14) in which a layer composed of metal or metal oxide of cerium and lanthanum is laminated by thermal decomposition on the upper layer thereof.

  In addition, as an electrode for hydrogen generation which is less affected by poisoning of iron ions, a platinum alloy comprising one kind of metal selected from the group of nickel, cobalt, copper, silver and iron and platinum, or a non-transition metal element and platinum. A hydrogen generation electrode consisting of a crystalline substance has been proposed (Patent Document 15).

  However, the influence of iron ion poisoning is still large, the reverse current resistance is not sufficient, and further improvement of the hydrogen generation electrode is desired.

  As described above, in order to reduce the power consumption of the water or alkali metal chloride aqueous solution electrolysis industry, various methods for using hydrogen generation electrodes and hydrogen generation electrodes have conventionally been proposed. The electrode for hydrogen generation has hydrogen over voltage characteristics, sufficient resistance to poisoning to iron ions in the catholyte, and sufficient durability in industrial use where it must be started and stopped, and has industrially satisfactory characteristics. The hydrogen generation electrode has not been obtained yet.

Patent No. 3319370 gazette Patent No. 3358465 gazette JP-A-59-25985 Japanese Patent Application Laid-Open No. 59-232284 Japanese Patent Application Laid-Open No. 57-23083 Japanese Patent Application Laid-Open No. 60-56082 Japanese Patent Application Laid-Open No. 60-59090 Japanese Patent Application Laid-Open No. 63-72897 JP, 2000-239882, A Patent No. 4927006 Patent No. 527 1429 Patent No. 4274489 Patent No. 4346070 Japanese Examined Patent Publication No. 6-033481 JP 2005-330575 A

  The object of the present invention is to be used in water or alkali metal chloride aqueous solution electrolysis industry etc., hydrogen overvoltage is sufficiently low, and there is no influence of poisoning by iron ion, and furthermore, during operation or during start / stop An electrode for hydrogen generation excellent in durability without rising of hydrogen overvoltage and falling off of a support, a method of manufacturing the hydrogen generation electrode, and an electrolysis method using the hydrogen generation electrode as a cathode Alternatively, it is to reduce the power consumption of the alkali metal chloride aqueous solution electrolysis industry and the like. In particular, we will improve the active cathode for hydrogen generation by supporting a catalyst consisting of transition metals such as platinum and nickel by thermal decomposition, with low hydrogen overvoltage, and resistance to poisoning by iron ions, and during or after electrolysis operation. An object of the present invention is to provide an electrode for hydrogen generation with improved resistance to reverse current flowing during start-up operation and improved electrode durability.

  The present invention relates to an electrode for hydrogen generation in which a catalyst layer containing platinum, nickel and ruthenium as main components is supported on a conductive substrate.

  Hereinafter, the present invention will be described in detail.

  An electrode for hydrogen generation in which a catalyst layer consisting of platinum, nickel and ruthenium is supported on a conductive substrate, for example, applies a platinum compound solution, a nickel compound solution and a ruthenium compound solution on a conductive substrate, It is obtained by forming a catalyst layer by reduction treatment of a catalyst layer precursor obtained by drying at a temperature of 200 ° C. or less and then pyrolyzing at a temperature of more than 200 ° C. and 700 ° C., and the catalyst layer after reduction Among them, an alloy of platinum, nickel and ruthenium is formed. The catalyst layer has excellent performance as a hydrogen generation electrode.

  Although the details of the ratio of the alloy of platinum, nickel and ruthenium in the catalyst layer after reduction are unknown, according to the result of X-ray diffraction, the majority is an alloy of platinum, nickel and ruthenium, Amorphous metal that remains as ruthenium oxide or nickel oxide and does not have an X-ray peak, or after prolonged electrolysis in water or aqueous alkali metal hydroxide solution, water on the surface of platinum, nickel and ruthenium alloys I think that the oxide may be formed.

  In addition, since the hydrogen overvoltage is low and the reverse current resistance is also excellent, the content of ruthenium in the catalyst layer is preferably 1 mol% to 55 mol%, and more preferably 1 mol% to 33 mol%, Not only low hydrogen overvoltage but also excellent reverse current resistance, it is preferable that the ruthenium content in the catalyst layer is 20 to 50 mol%, the nickel content is 40 to 25 mol%, and the balance is platinum. Preferably, the ruthenium content in the catalyst layer is 20 to 32 mol%, the nickel content is 40 to 34 mol%, and the balance is platinum.

  Furthermore, the reduction treatment is preferably electrochemical reduction, more preferably electrochemical reduction when water or an aqueous solution of an alkali metal chloride is electrolyzed.

  The conductive substrate used in the present invention includes, for example, nickel, iron, copper, titanium and stainless alloy steels, and in particular, nickel having excellent corrosion resistance to an alkaline solution is preferable. The shape of the conductive substrate is not particularly limited, and in general, it may be a shape in accordance with the electrode of the electrolytic cell, and for example, a flat plate, a curved plate or the like can be used.

  The conductive substrate used in the present invention is preferably a porous plate, and for example, expanded metal, punched metal, net or the like can be used.

  The method for producing the hydrogen generation electrode of the present invention may be any production method as long as a catalyst layer comprising platinum, nickel and ruthenium can be supported on the conductive substrate. For example, an electroplating method, a dispersion plating method, a thermal spraying method, a thermal decomposition method, an arc ion plating method or the like can be used. However, when using these known manufacturing methods, in order to support a catalyst layer consisting of platinum, nickel and ruthenium on a conductive substrate, it is necessary to carefully study and set manufacturing conditions and raw materials. It is not possible to produce the electrode for hydrogen generation supporting the catalyst layer consisting of platinum, nickel and ruthenium on the conductive substrate provided by the present invention simply by applying the known production method.

  Hereinafter, a thermal decomposition method will be described as an example of a specific method for producing a hydrogen generation electrode in which a catalyst layer consisting of platinum, nickel and ruthenium is supported on a conductive substrate provided by the present invention.

  The thermal decomposition method referred to in the present invention refers to a series of operations of applying a platinum compound solution, a nickel compound solution and a ruthenium compound solution on a substrate, drying and thermal decomposition.

  The conductive substrate is preferably roughened in advance. This is because roughening can increase the contact surface area, and the adhesion between the substrate and the carrier is improved. The means for surface roughening is not particularly limited, and a known method such as sand blasting, etching with boric acid or hydrochloric acid solution, washing with water and drying can be used.

  As a platinum compound used in the method for producing an electrode for hydrogen generation of the present invention, chloroplatinic acid, dinitrodiamine platinum and the like can be used. In particular, it is preferable to use dinitrodiammine platinum which forms an ammine complex because the crystallite diameter of the platinum alloy after reduction treatment can be refined to, for example, 200 angstroms or less, and the reaction specific surface area can be increased. This is because the dinitrodiamine platinum has a high thermal decomposition temperature of about 550 ° C., thereby suppressing aggregation of platinum during thermal decomposition, and a film in which platinum, nickel and ruthenium are uniformly mixed after thermal decomposition is obtained, and reduction It is presumed that the treatment results in an alloy with a fine crystallite diameter.

  On the other hand, the nickel compound and the ruthenium compound used in the production method of the present invention are not particularly limited, and nitrate, sulfate, chloride, carbonate, acetate, sulfamate and the like can be used.

  Furthermore, as a solvent for dissolving the platinum compound, the nickel compound and the ruthenium compound, in order to increase the surface area of the support, those in which these raw materials can be completely dissolved are preferable. Water or nitric acid, hydrochloric acid, sulfuric acid, acetic acid Inorganic acids such as solutions, organic solvents such as methanol, ethanol, propanol, butanol or the like, or mixtures thereof may also be used. Also, the pH of the coating solution may be adjusted and used for the purpose of suppressing the dissolution of the base metal into the coating solution, and complex salts such as lysine and citric acid may be added to increase the surface area of the support, nickel and The ruthenium may be complexed.

  In the method of applying the compound solution to the conductive substrate, the platinum compound solution, the nickel compound solution and the ruthenium compound solution may be separately applied to the conductive substrate using a brush or the like, or the platinum compound and the nickel compound A mixed solution of the compound and the ruthenium compound may be prepared and applied to the conductive substrate using a brush or the like. In addition to the brushing, all known methods such as a spray method and a dip coating method can be suitably used.

  The drying temperature after application may be 5 to 60 minutes at a temperature of 200 ° C. or less, preferably 150 ° C. or less.

  The thermal decomposition temperature after drying may be in the range of more than 200 ° C. and 700 ° C. or less for 5 to 60 minutes, preferably in the range of more than 350 ° C. and 500 ° C. or less. For example, when a dinitrodiamine platinum solution is used, the thermal decomposition temperature of the dinitrodiamine platinum is 550 ° C., and by performing thermal decomposition at 500 ° C. or less, sintering of platinum is suppressed, and hydrogen overvoltage is even lower Electrode can be obtained.

The above-described coating, drying, and thermal decomposition sequence is repeated once or several times. The number of times the thermal decomposition operation is repeated is not particularly limited, but in order to obtain a low hydrogen overvoltage, it is preferable to repeat the thermal decomposition operation until the supported amount of the alloy after reduction treatment is 0.5 g / m ² or more, 1 g / It is further preferable to repeat the thermal decomposition operation until it becomes m ² or more.

  After the thermal decomposition, a reduction treatment for reducing and alloying the support (catalyst layer precursor) to a metallic state is performed. The reduction method is not particularly limited, but chemical reduction by contact with a substance having strong reducing power such as hydrazine, formic acid or oxalic acid, or electrochemical reduction which gives reduction potential to platinum, nickel and ruthenium can be used. .

  For example, the electrochemical reduction method is a method of providing a potential necessary for reduction of a support (catalyst layer precursor) composed of platinum, nickel and ruthenium. Standard electrode potentials of platinum, nickel and ruthenium in an aqueous solution have already been disclosed ("Electrochemical Handbook" 5th Edition Maruzen Publications page 92 to 95), and the potential required for reduction can be estimated from the standard electrode potential It is.

  In reducing and alloying the pyrolyzed support (catalyst layer precursor) to the metallic state, the electrochemical reduction method converts the pyrolyzed support (catalyst layer precursor) to the metallic state while performing electrolysis. It is convenient because reduction and alloying can be performed, and there is no need to carry out the above-mentioned support reduction treatment separately from electrolysis.

  This electrochemical reduction treatment is usually carried out by an electrochemical reduction treatment in water or an aqueous alkali metal chloride solution.

  When the electrode for hydrogen generation of the present invention obtained in this manner is used as an electrode for hydrogen generation in the electrolysis application of an aqueous solution of an alkali metal chloride such as water or sodium chloride, a low hydrogen overpotential is obtained, and The low over-voltage characteristics are stably maintained for a long period without special iron ion mixing, and the catalyst does not come off or come off during stop or restart operation, that is, hydrogen over-voltage performance and durability Very good electrode for hydrogen generation.

  Therefore, in the field of electrolysis of an aqueous solution of alkali metal chloride such as water or sodium chloride, the energy required for the electrolysis industry can be easily reduced simply by changing the electrode for hydrogen generation to the electrode for hydrogen generation provided by the present invention. It becomes possible.

  In the electrolysis industry of aqueous solution of alkali metal chloride such as water or sodium chloride, the electrode for hydrogen generation is used as a cathode and the water or the aqueous solution of alkali metal chloride is electrolyzed in an electrolytic cell in which an anode is disposed with a diaphragm interposed. The so-called sodium chloride electrolysis, which produces hydrogen gas and an aqueous solution of alkali metal hydroxide from the cathode and oxygen gas or chlorine gas from the anode, is a typical example of electrolysis industry.

  As the diaphragm, it is preferable to use a cation exchange membrane in terms of current efficiency and energy efficiency due to low electrolytic cell voltage.

  An electrode for hydrogen generation, in which a catalyst layer composed mainly of platinum, nickel and ruthenium is supported on the conductive substrate of the present invention, has low hydrogen overpotential performance and is excellent in durability. The electrode can be manufactured by a simple method of forming a catalyst layer precursor by forming a catalyst layer precursor on a conductive substrate and forming the catalyst layer, and thus obtained according to the present invention The hydrogen generation electrode does not increase the hydrogen overvoltage due to the poisoning of iron ions in the electrolytic solution, which is considered to be a drawback of the conventional platinum-based catalyst, and flows during the electrolytic operation or during the stop / start operation. The catalyst does not come off or drop off due to the reverse current. Therefore, it is possible to stably maintain the low hydrogen overvoltage characteristic inherent to platinum over a long period of time, especially water or alkali which is forced to be mixed with iron in the reverse current or catholyte flowing several times a year during stopping and restarting. It is possible to greatly reduce the energy required for the electrolysis industry of metal aqueous solutions.

FIG. 2 is a diagram showing an X-ray diffraction chart of a hydrogen generation electrode of Example 1.

  The invention is illustrated by the following examples.

In addition, each evaluation was implemented by the method shown below.
(Hydrogen overvoltage measurement)
Using a 32 wt% sodium hydroxide aqueous solution (approximately 1 L volume), perform water electrolysis on the counter electrode for 10 minutes under the conditions of Ni, temperature 88 ° C., current density 6.0 kA / m ^{2 by} the current interrupter method. , Hydrogen over voltage was measured.
(Iron poisoning resistance evaluation)
After measuring the hydrogen overpotential by the above method, add iron standard solution (Kanto Chemical Co., Ltd., Fe: 1000 mg / l) into the electrolyte (volume: about 100 mL) of 32 wt% sodium hydroxide aqueous solution to make the iron concentration 10 ppm. In the electrolyte, water is electrolyzed for 2 hours under the condition of Ni and current density 6.0 kA / m ^{2 in} the electrolyte, hydrogen over voltage is measured again by the above method, and the difference from the hydrogen over voltage previously measured. The iron poisoning resistance evaluation was carried out using this value as the overvoltage rise value due to iron poisoning.
(Reverse current resistance evaluation)
After measuring the hydrogen overpotential by the above method, in 0.5M sodium sulfate, Pt as a counter electrode, saturated calomel electrode as a reference electrode, scanning potential -1.0 V to 0.6 V vs SCE, scanning speed 50 mV / s, initial potential Perform cyclic voltammetry under the condition of 0.1 V vs SCE, cycle number 250 cycles, measure the hydrogen overvoltage again by the above method, find the difference from the previously measured hydrogen overvoltage, and use that value as the overvoltage increase value by reverse current Then, the reverse current resistance evaluation was carried out based on this overvoltage rise value.

  In addition, the hydrogen overvoltage is measured by the above method and the cyclic voltammetry measurement is performed after the measurement of the hydrogen overvoltage by the above method, and the hydrogen overvoltage is measured again and dissolved with aqua regia, and an ICP emission analyzer (Perkin The supported amount was determined using an Elmer company, model optima 3000), the rate of change of the amount of platinum was determined from these values, and the value was used as the rate of remaining platinum due to reverse current.

Example 1
As a conductive base material, nickel expanded mesh (5.0 × 5.0 cm) was used, and etching was carried out at a temperature of 50 ° C. for 15 minutes using a 10 wt% hydrochloric acid solution as roughening treatment, followed by washing with water and drying.

  Then, using dinitrodiammine platinum nitric acid solution (Tanaka precious metal product), nickel nitrate hexahydrate and nitric acid solution of ruthenium nitrate (Tanaka precious metal product) and water, 34 mole% platinum, 34 mole% nickel and ruthenium A 32 mol% coating solution was prepared.

  The contents of platinum, nickel and ruthenium in the catalyst layer are determined by the contents (mol%) of platinum, nickel and ruthenium in the coating solution in the platinum compound solution, the nickel compound solution and the ruthenium compound solution.

  Next, the coating solution is applied to the entire surface of the nickel expanded mesh using a brush, dried at 80 ° C. for 15 minutes in a hot air dryer, and then using a box muffle furnace (Advantec Toyo K. KM-600, internal volume 27 L) The mixture was pyrolyzed at 500 ° C. for 15 minutes under air flow. This series of operations was repeated five times.

The hydrogen generation electrode obtained as described above was subjected to the conditions of Ni at a temperature of 88 ° C. and a current density of 6.0 kA / m ^{2 using} a 32 wt% sodium hydroxide aqueous solution (approximately 1 L in volume) as the counter electrode. After conducting water electrolysis for 10 minutes, the hydrogen generation electrode was taken out, dried, and the X-ray diffraction chart when the X-ray diffraction was carried out is shown in FIG.

From this FIG. 1, it is clear that although the alloy of platinum, nickel and ruthenium is the main peak, the peaks of RuO ₂ and NiO are also present.

  When hydrogen over voltage measurement is performed, the hydrogen over voltage is 74.5mV, the excess voltage increase due to iron poisoning is 17.8mV, the excess voltage increase due to reverse current is 2.0mV, and the residual ratio of platinum due to reverse current is 100 %Met. The results are shown in Table 1.

Example 2-4
An electrode was produced in the same manner as in Example 1 except that the compositions of platinum, nickel and ruthenium in Example 1 were changed to the compositions shown in Table 1, respectively.

  In Example 2, the hydrogen overvoltage was 75.7 mV when hydrogen overvoltage was measured, and the amount of increase in overvoltage due to iron poisoning was 13.3 mV, and the amount of increase in overvoltage due to reverse current was 15.9 mV. The results are shown in Table 1.

  In Example 3, the hydrogen overvoltage was 79.0 mV when hydrogen overvoltage was measured, and the amount of increase in overvoltage due to iron poisoning was 14.1 mV, and the amount of increase in overvoltage due to reverse current was 26.2 mV. The results are shown in Table 1.

  In Example 4, the hydrogen overvoltage was 73.2 mV when hydrogen overvoltage was measured, and the amount of increase in overvoltage due to iron poisoning was 16.0 mV, and the amount of increase in overvoltage due to reverse current was 12.4 mV. The results are shown in Table 1.

Comparative Example 1
In Example 1, using a dinitrodiammine platinum nitric acid solution, nickel nitrate hexahydrate and water, a coating solution having 50 mol% of platinum and 50 mol% of nickel was prepared and coated except for using this. An electrode was produced in the same manner as in 1.

  When hydrogen over voltage measurement is performed, the hydrogen over voltage is 82.9 mV, the over voltage increase by iron poisoning is 20.0 mV, the over voltage increase by reverse current is 16.4 mV, and the residual ratio of platinum by reverse current is 93 %Met. The results are shown in Table 1.

Comparative example 2
Example 1 Example 1 was repeated except that a coating solution containing 50 mol% of platinum and 50 mol% of ruthenium was prepared using a dinitrodiammine platinum nitric acid solution, a nitric acid solution of ruthenium nitrate, and water. The electrode was produced by the same operation as in.

  When hydrogen over voltage measurement was performed, the hydrogen over voltage was 88.7 mV. The results are shown in Table 1.

全ての実施例において、水素過電圧が比較例の範囲の水素過電圧より低くなっており、
加えて、すべての実施例において、鉄被毒による過電圧上昇量は比較例１での結果より低い値となり、かつ、実施例１−２において、逆電流による過電圧上昇量は比較例１での結果より低い値となっていた。また、実施例１の白金残存率は比較例１に比べ高い値となっていた。よって、本発明の水素発生用電極は優れた水素過電圧性能と鉄被毒および逆電流に対する耐久性を有することが上記表１に示されている。

In all the examples, the hydrogen overpotential is lower than that of the comparative example,
In addition, in all the Examples, the amount of increase in overvoltage due to iron poisoning is a lower value than the result in Comparative Example 1, and in Example 1-2, the amount of increase in overvoltage due to reverse current is the result in Comparative Example 1 It was a lower value. In addition, the platinum residual rate in Example 1 was higher than that in Comparative Example 1. Accordingly, it is shown in Table 1 that the electrode for hydrogen generation of the present invention has excellent hydrogen over-voltage performance and durability against iron poisoning and reverse current.

  Among these, Examples 1 to 2 and Example 4 having low hydrogen overvoltage are preferable, and a catalyst layer having a composition in which the content of Ru is 20 to 55 mol%, Ni is 40 to 34 mol%, and the balance is Pt An electrode for hydrogen generation is preferred.

The electrode for hydrogen generation of the present invention can be used for the electrolysis of water or the electrolysis of an aqueous solution of an alkali metal chloride such as sodium chloride, and has the possibility of being used for a wide range of electrolysis industry as the sodium chloride electrolysis industry is the first.

1: Peak attributed to substrate (nickel) 2: Peak attributed to alloy (platinum-nickel-ruthenium alloy) 3: Peak attributed to RuO ₂ : Peak attributed to NiO

Claims (7)

An electrode for hydrogen generation comprising a catalyst layer comprising platinum, nickel and ruthenium as main components and platinum, nickel and ruthenium in an alloy state supported on a conductive substrate. The ruthenium content in the said catalyst layer is 1 to 55 mol%, The electrode for hydrogen generation of Claim 1 characterized by the above-mentioned. The hydrogen generation electrode according to claim 2 , wherein the content of ruthenium in the catalyst layer is 20 to 50 mol%, the content of nickel is 40 to 25 mol%, and the balance is platinum. The method for producing a hydrogen generation electrode according to any one of claims 1 to 3 , wherein a catalyst layer precursor is formed on a conductive substrate and then reduction treatment is performed to form the catalyst layer. The method for producing a hydrogen generation electrode according to claim 4 , wherein the reduction treatment is an electrochemical reduction treatment in water or an aqueous alkali metal chloride solution. The water or the alkali metal chloride aqueous solution is electrolyzed in an electrolytic cell using the hydrogen generation electrode according to any one of claims 1 to 3 as a cathode and arranging the anode with a diaphragm interposed, from above the cathode An electrolytic method of producing hydrogen gas and an aqueous alkali metal hydroxide solution and producing oxygen gas or chlorine gas from the anode. The electrolytic method according to claim 6 , wherein the diaphragm is a cation exchange membrane.

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