JP2009209379A - Water electrolysis apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water electrolysis apparatus which can reduce its cost and improve water electrolysis performance. <P>SOLUTION: The first water electrolysis apparatus 10A includes a water electrolysis cell 15A which includes: a polymer solid electrolyte membrane 11; a hydrogen pole catalyst layer 12A and an oxygen pole catalyst layer 13A on both sides of the polymer solid electrolyte membrane 11; and power feeders 14A for feeding an electric power to the hydrogen pole catalyst layer 12A and the oxygen pole catalyst layer 13A, which are respectively arranged on the outside of the hydrogen pole catalyst layer 12A and the oxygen pole catalyst layer 13A. A cell stack is structured by stacking a plurality of water electrolysis cells 15A while sandwiching each cell with a plurality of separator plates 16 and 16. The hydrogen pole catalyst layer 12A is made by mixing a Pt-carrying carbon catalyst 17 which carries Pt particles thereon with Pt-black particles 19. Thereby, the water electrolysis apparatus can reduce the amount of the Pt-black particles 19 used in the hydrogen pole catalyst layer 12A, and has also a water electrolysis performance equal to or more excellent than a conventional one. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a water electrolysis apparatus that electrolyzes water using an electrochemical reaction.

  The water electrolysis cell uses an electrochemical reaction to electrolyze water to generate hydrogen, oxygen, and the like. For example, a water electrolysis apparatus that uses a polymer electrolyte membrane as an electrolyte includes a polymer solid electrolyte membrane, a catalyst electrode (hydrogen electrode catalyst, oxygen electrode catalyst), a power feeder for flowing current through the catalyst electrode, and a separator that contains them It has.

  For example, an example of a conventional water electrolysis apparatus is shown in FIG. As shown in FIG. 14, a conventional water electrolysis apparatus 100 is configured by sandwiching a water electrolysis cell 101 with a conductive separator plate 102. The water electrolysis cell 101 includes a polymer solid electrolyte membrane 103 and its It comprises a hydrogen electrode catalyst layer 104 and an oxygen electrode catalyst layer 105 provided on both sides, and a power feeding body 106 arranged outside each catalyst layer. In the figure, reference numeral 107 denotes a rubber packing. In addition, a cell stack structure in which a plurality of water electrolysis cells 101 are stacked via separator plates 102 can be formed.

Further, platinum (Pt) black particles 110 are formed on the hydrogen electrode catalyst layer 104, Pt black particles 110 and iridium oxide (IrO ₂ ) particles 111 are formed on the oxygen electrode catalyst layer 105, and titanium (Ti) is formed on the separator plate 102. Each is used. This is because the water electrolysis potential is high and the strongly solid polymer electrolyte membrane 103 is used as the cell structure, so that inexpensive general-purpose metals cannot be used, and only noble metal plating and noble metal catalysts such as Pt can be used. It is.

  Further, a titanium mesh subjected to Pt plating is used for the power supply body 106. This is because when carbon is used on the oxygen electrode side, it reacts with oxygen at a high potential to become carbon dioxide gas and is corroded. Further, since carbon is oxidized and decomposed at 1.2 V or higher, it cannot be used in an oxygen atmosphere, and carbon cannot be used as the power supply body 106.

By supplying water to the anode side having the oxygen electrode catalyst layer 105 and applying a voltage to the power feeding body 106, water is decomposed on the anode side to generate oxygen and hydrogen ions as shown in the following formula (1). Moves through the polymer solid electrolyte membrane 103.
H ₂ O → 2H ⁺ + 2e ⁻ + 1 / 2O ₂ ↑ (1)

Then, on the cathode side having the hydrogen electrode catalyst layer 104, hydrogen ions that have moved through the solid polymer electrolyte membrane 103 receive electrons as shown in the following formula (2) to generate hydrogen.
2H ⁺ + 2e ⁻ → H ₂ ↑ (2)

  As described above, the conventional water electrolysis apparatus 100 generates hydrogen by electrolyzing water (see Patent Document 1 and Patent Document 2).

Japanese Patent Laid-Open No. 2005-289838 JP 08-269761 A

  However, in the conventional water electrolysis apparatus 100, the Pt black particles 110 are used as the catalyst and the Pt-plated titanium mesh is used as the power supply body 106, so that the amount of Pt used is large and the water electrolysis cell 101 is used. There is a problem that the cost is high.

  In view of the above problems, an object of the present invention is to provide a water electrolysis device capable of reducing costs and improving water electrolysis performance.

  The first invention of the present invention for solving the above-mentioned problems includes a hydrogen electrode catalyst layer and an oxygen electrode catalyst layer on both sides of a polymer solid electrolyte membrane, and the hydrogen electrode catalyst layer and the oxygen electrode catalyst layer. In a water electrolysis apparatus provided with a water electrolysis cell in which a power feeding body for feeding power is arranged outside the hydrogen electrode catalyst layer and the oxygen electrode catalyst layer, the hydrogen electrode catalyst layer carries platinum particles carrying platinum particles. A water electrolysis apparatus comprising a carbon catalyst.

  A second invention is the water electrolysis apparatus according to the first invention, wherein the hydrogen electrode catalyst layer is a mixture of the platinum-supported carbon catalyst and platinum black particles.

  A third invention is characterized in that, in the first or second invention, the oxygen electrode catalyst layer is a mixture of platinum black particles and iridium oxide particles, or consists of only the iridium oxide particles. It is in a water electrolysis device.

  According to a fourth invention, in any one of the first to third inventions, the power feeding body includes a titanium mesh plated with platinum, a photoetched titanium mesh having a platinum plated layer, and a platinum deposited layer deposited with platinum. The water electrolysis apparatus is any one of etching titanium meshes.

A fifth invention is the water electrolysis apparatus according to the third or fourth invention, wherein the iridium oxide particles are high specific surface area iridium oxide particles having a specific surface area of 50 m ² / g or more.

  A sixth invention is a water electrolysis apparatus according to any one of the first to fifth inventions, wherein a plurality of the water electrolysis cells are sandwiched between a plurality of separator plates to form a cell stack. is there.

  According to the present invention, since the hydrogen electrode catalyst layer provided on one side of the polymer solid electrolyte membrane contains a platinum-supported carbon catalyst supporting platinum particles, the amount of platinum (Pt) black particles used can be reduced. The Pt specific surface area can be increased by supporting Pt particles on the surface of the carbon support. For this reason, even if the reaction area on the Pt surface is small, a water electrolysis reaction equivalent to the case where only Pt black particles are used is possible, and the cost can be reduced and the water electrolysis performance can be improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

[First embodiment]
A water electrolysis apparatus according to a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram schematically showing the configuration of the water electrolysis apparatus according to the first embodiment of the present invention.
As shown in FIG. 1, a first water electrolysis apparatus 10A according to the present embodiment includes a polymer solid electrolyte membrane 11, a hydrogen electrode catalyst layer 12A and an oxygen electrode catalyst layer 13A on both sides thereof, A water electrolysis cell 15A in which a power feeding body 14A for feeding power to the electrode catalyst layer 12A and the oxygen electrode catalyst layer 13A is disposed outside the hydrogen electrode catalyst layer 12A and the oxygen electrode catalyst layer 13A, respectively, and a plurality of the water electrolysis cells 15A are provided. In a water electrolysis apparatus in which a cell stack is formed by stacking a plurality of layers while being sandwiched between separator plates 16 and 16, the hydrogen electrode catalyst layer 12A includes a platinum (Pt) -supported carbon catalyst 17 supporting platinum (Pt) particles. . Note that this embodiment mode is described using a single cell structure.
Moreover, in the figure, the code | symbol 18 illustrates a rubber packing.

  Here, in the present invention, the hydrogen electrode catalyst layer 12 </ b> A is a mixture of platinum (Pt) black particles 19 and a Pt-supported carbon catalyst 17. The hydrogen electrode catalyst layer 12A contains Pt black particles 19 and a Pt-supported carbon catalyst 17 in which the Pt black particles 19 and the Pt-supported carbon catalyst 17 are dispersed in a solution from the polymer electrolyte solution 21 and the water repellent agent 22. It is formed by applying a solution to be applied.

  In the present embodiment, a mixture of Pt black particles 19 and Pt-supported carbon catalyst 17 is used as hydrogen electrode catalyst layer 12A. However, only Pt-supported carbon catalyst 17 is added without adding Pt black particles 19. May be used.

The oxygen electrode catalyst layer 13 </ _b > A is a mixture of platinum (Pt) black particles 19 and iridium oxide (IrO ₂ ) particles 20. The oxygen electrode catalyst layer 13A is plated on the surface in contact with the power feeder 14A using a solution in which Pt black particles 19 and iridium oxide (IrO ₂ ) particles 20 are dispersed in a polymer electrolyte solution 21 and a water repellent agent 22. Done and formed. In the present embodiment, a mixture of Pt black particles 19 and IrO ₂ particles 20 is used as the oxygen electrode catalyst layer 13A. However, only the IrO ₂ particles 20 are used without adding the Pt black particles 19. You may do it.

  The power feeding body 14A is made of titanium (Ti) as a material, and a titanium mesh whose surface is Pt plated is used. The power supply body 14A is not limited to this, and for example, a cloth made of a sintered titanium metal fiber web having a large number of voids between the cloth fibers may be used.

  Examples of the polymer solid electrolyte membrane 11 include a fluororesin cation exchange membrane having a sulfonic acid group, such as “NAFION (registered trademark)” N-112, N-115, N-117, NE-1110 (trade name). : Manufactured by DuPont) or the like. Other fluororesin-based cation exchange membranes include fluorine-based cation exchange membranes (trade name: Aciplex-F (Aciplex F)) manufactured by Asahi Kasei Chemicals Co., Ltd. and fluorine-based cation exchange membranes (trade name) manufactured by Asahi Glass Co., Ltd. : Flemion) can be used. The polymer solid electrolyte membrane 11 is not particularly limited to this.

In the first water electrolysis apparatus 10A according to the present embodiment, when water is supplied to the anode side having the oxygen electrode catalyst layer 13A and voltage is applied to the power feeder 14A, the water is decomposed on the anode side, and oxygen is As a result, hydrogen ions move in the polymer electrolyte membrane 11 (see the following formula (1)).
H ₂ O → 2H ⁺ + 2e ⁻ + ½O ₂ ↑ (1)

Then, on the cathode side having the hydrogen electrode catalyst layer 12A, hydrogen ions that have moved through the polymer solid electrolyte membrane 11 receive electrons and generate hydrogen (see the following formula (2)).
2H ⁺ + 2e ⁻ → H ₂ ↑ (2)

  In the first water electrolysis apparatus 10A according to the present embodiment, since the hydrogen electrode catalyst layer 12A is made by mixing the Pt black particles 19 and the Pt-supported carbon catalyst 17, the hydrogen electrode catalyst layer 12A. The amount of Pt black particles 19 used in the above can be reduced, and water electrolysis performance equivalent to or higher than that of the conventional water electrolysis apparatus 100 as shown in FIG. 14 can be obtained.

This is because the Pt black particles 110 used in the hydrogen electrode catalyst layer 104 of the conventional water electrolysis apparatus 100 as shown in FIG. 14 have a particle size of about several tens of μm and a specific surface area of several m ² / g or less. On the other hand, the specific surface area of the Pt particles supported on the carbon support surface of the Pt-supported carbon catalyst 17 corresponds to 100 m ² / g or more.

  For this reason, even if the total Pt use weight of the Pt-supported carbon catalyst 17 and platinum (Pt) black is small, the hydrogen electrode catalyst layer 12A is formed only from the Pt black particles 110 as in the conventional water electrolysis apparatus 100 as shown in FIG. It has a reaction area equivalent to that of the resulting catalyst layer, and can make a water electrolysis reaction equivalent to the conventional one.

  Thus, according to the first water electrolysis apparatus 10A according to the present embodiment, the hydrogen electrode catalyst layer 12A is formed by mixing the Pt black particles 19 and the Pt-supported carbon catalyst 17, so that the catalyst Even if the amount of Pt black particles 19 used in the layer is decreased, the specific surface area of the Pt particles supported on the carbon support surface of the Pt-supported carbon catalyst 17 is increased. A water electrolysis reaction equivalent to the case where only the Pt black particles 19 are used is possible, so that the cost can be reduced and the water electrolysis performance can be improved.

  In the present embodiment, a pair of separator plates 16 is provided on both sides of the water electrolysis cell 15A. However, at least two water electrolysis cells 15A may be stacked via the separator plate 16. Good.

[Second Embodiment]
A water electrolysis apparatus according to a second embodiment of the present invention will be described with reference to FIG.
FIG. 2 is a conceptual diagram schematically showing the configuration of the water electrolysis apparatus according to the second embodiment of the present invention.
As shown in FIG. 2, the second water electrolysis apparatus 10B according to the present embodiment is the same as the configuration of the first water electrolysis apparatus 10A according to the first embodiment shown in FIG. The same reference numerals are given to the members, and duplicate descriptions are omitted.

  As shown in FIG. 2, the second water electrolysis apparatus 10B according to the present embodiment is replaced with a power feeder 14A of the first water electrolysis apparatus 10A according to the first embodiment shown in FIG. A photoetching titanium mesh 24 having a Pt plating layer 23 plated with Pt on the surface is used.

  That is, the water electrolysis cell 15B of the second water electrolysis apparatus 10B according to the present embodiment has a power feeding body 14B made of a photoetched titanium mesh 24 having a Pt plating layer 23 on the surface in place of the power feeding body 14A. is there.

  By using a power supply 14B made of a photoetching titanium mesh 24 having a Pt plating layer 23 on the surface, the amount of Pt black particles 19 added to each of the catalyst layers of the hydrogen electrode catalyst layer 12A and the oxygen electrode catalyst layer 13A is greatly increased. Even if it reduces, the water electrolysis performance equivalent to the conventional water electrolysis apparatus 100 as shown in FIG. 14 can be obtained.

  This is because Pt is added to ensure the electron conductivity inside the hydrogen electrode catalyst layer 12A and the oxygen electrode catalyst layer 13A, but a flat Pt plating layer 23 is formed on the surface of the power supply 14B. Therefore, the contact area between the catalyst surface of the hydrogen electrode catalyst layer 12A and the oxygen electrode catalyst layer 13A with the Pt plating layer 23 is increased, and electron conductivity can be ensured.

  Further, the thickness of the Pt plating layer 23 is preferably, for example, about 1 μm to 3 μm, and practically about 2 μm. In terms of cost, the thinner the film thickness, the lower the amount of platinum used, which is advantageous in terms of cost. However, in general plating methods, pinholes (unplated parts) occur at thicknesses of 1 μm or less. This is because it becomes easier.

  3 and 4 are conceptual diagrams simply showing other configurations of the water electrolysis apparatus according to the present embodiment. As shown in FIG. 3, the second water electrolysis apparatus 10C according to the present embodiment replaces the hydrogen electrode catalyst layer 12A formed by mixing the Pt black particles 19 and the Pt-supported carbon catalyst 17 with Pt black particles. A water electrolysis cell 15C having a hydrogen electrode catalyst layer 12B made of only the Pt-supported carbon catalyst 17 without adding 19 may be used.

Further, as shown in FIG. 4, the second water electrolysis apparatus 10D according to the present embodiment replaces the oxygen electrode catalyst layer 13A formed by mixing Pt black particles 19 and IrO ₂ particles 20 with Pt black. without the addition of particles 19, it may be used water electrolysis cell 15C having an oxygen electrode catalyst layer 13B composed of only IrO ₂ particles 20.

Even if the hydrogen electrode catalyst layer 12B made only of the Pt-supported carbon catalyst 17 without adding the Pt black particles 19 or the oxygen electrode catalyst layer 13B made only of the IrO ₂ particles 20 without adding the Pt black particles 19, By providing the power supply body 14B made of the photoetching titanium mesh 24 having the Pt plating layer 23 on the surface, the contact area of the catalyst surface with the Pt plating layer 23 on the catalyst surface can be increased, and the electron conductivity can be ensured. . Therefore, water electrolysis performance equivalent to that of the conventional water electrolysis apparatus 100 as shown in FIG. 14 can be obtained without adding the Pt black particles 19.

  Thus, according to 2nd water electrolysis apparatus 10B-D which concerns on this Embodiment, by having the electric power feeding body 14B which consists of the photoetching titanium mesh 24 which has the Pt plating layer 23 on the surface, water electrolysis cell 15B The amount of Pt used per unit area can be significantly reduced, and even if the amount of Pt used is reduced, a water electrolysis reaction equivalent to the conventional one can be made possible.

[Third embodiment]
A water electrolysis apparatus according to a third embodiment of the present invention will be described with reference to FIG.
FIG. 5 is a conceptual diagram schematically showing the configuration of the water electrolysis apparatus according to the third embodiment of the present invention.
As shown in FIG. 5, the third water electrolysis apparatus 10E according to the present embodiment is the same as the configuration of the second water electrolysis apparatus 10C according to the second embodiment shown in FIG. The same reference numerals are given to the members, and duplicate descriptions are omitted.

As shown in FIG. 5, the third water electrolysis apparatus 10E according to the present embodiment compares the IrO ₂ particles 20 of the second water electrolysis apparatus 10C according to the second embodiment shown in FIG. High specific surface area iridium oxide (IrO ₂ ) particles 25 having a surface area of 50 m ² / g or more are obtained.

That is, the water electrolysis cell 15E of the third water electrolysis apparatus 10E according to the present embodiment is composed of high specific surface area IrO ₂ particles 25 having a specific surface area of 50 m ² / g or more instead of the IrO ₂ particles 20. .

Since the high specific surface area IrO ₂ particles 25 having a specific surface area of 50 m ² / g or more are used for the oxygen electrode catalyst layer 13C, the oxygen electrode catalyst layer 13C can be made finer to the nano level than the IrO ₂ particles 20 and the specific surface area can be increased. The reaction area can be increased, and the water electrolysis performance can be significantly improved as compared with the conventional water electrolysis apparatus 100 as shown in FIG.

This is because the IrO ₂ particles 20 were difficult to achieve a water electrolysis efficiency of 80% or more at a current density of ² A / cm ² , for example, whereas the high specific surface area IrO ₂ particles 25 were IrO ₂ particles Since 20 is atomized and the specific surface area is increased to, for example, 50 m ² / g or more, and the catalytic reaction area is increased, it is possible to prevent the water electrolysis performance from being deteriorated even if the current value per unit area increases. is there.

6 and 7 are conceptual diagrams simply showing another configuration of the water electrolysis apparatus according to the present embodiment. As in the third water electrolysis apparatus 10F according to the present embodiment shown in FIG. 6, the water electrolysis cell having the oxygen electrode catalyst layer 13D made of only the high specific surface area IrO ₂ particles 25 without adding the Pt black particles 19 15F may be used. Also, as in the third water electrolysis device 10G according to this embodiment shown in FIG. 7, in place of the IrO ₂ particles 20 of the first water-electrolysis apparatus 10A according to the first embodiment shown in FIG. 1 A water electrolysis cell 15G having an oxygen electrode catalyst layer 13E using high specific surface area IrO ₂ particles 25 may be used. Alternatively, an oxygen electrode catalyst layer 13D made of only the high specific surface area IrO ₂ particles 25 to which the Pt black particles 19 are not added may be used.

  In addition, in the third water electrolysis apparatuses 10E to 10G according to the present embodiment, those obtained by adding the Pt black particles 19 to each catalyst layer may be used as the catalyst layers.

Thus, according to the third water electrolysis apparatuses 10E to 10G according to the present embodiment, the oxygen electrode catalyst layers 13C and 13D have a specific surface area of 50 m ² / g or more (more preferably 60 m ² / g or more). By using the high specific surface area IrO ₂ particles 25, the IrO ₂ particles 20 can be made finer to the nano level, the specific surface area can be increased, and the catalytic reaction area can be increased. Therefore, the current value per unit area is increased. However, it is possible to prevent deterioration of the water electrolysis performance and improve the water electrolysis performance.
[Fourth embodiment]

A water electrolysis apparatus according to a fourth embodiment of the present invention will be described with reference to FIG.
FIG. 8 is a conceptual diagram schematically showing the configuration of the water electrolysis apparatus according to the fourth embodiment of the present invention.
As shown in FIG. 8, the fourth water electrolysis apparatus 10H according to the present embodiment is the same as the configuration of the third water electrolysis apparatus 10E according to the third embodiment shown in FIG. The same reference numerals are given to the members, and duplicate descriptions are omitted.

  As shown in FIG. 8, the fourth water electrolysis apparatus 10H according to the present embodiment is replaced with a power feeder 14B of the third water electrolysis apparatus 10E according to the third embodiment shown in FIG. A power supply 14C made of a photoetching titanium mesh 24 having a Pt vapor deposition layer 26 on which Pt is vapor deposited is used.

  That is, the water electrolysis cell 15H of the fourth water electrolysis apparatus 10H according to the present embodiment has a power feeding body 14C made of a photoetched titanium mesh 24 having a Pt vapor deposition layer 26 on the surface.

  By using a power supply 14C made of a photoetched titanium mesh 24 having a Pt vapor deposition layer 26 on the surface, the second water electrolysis apparatuses 10B to 10D according to the second embodiment shown in FIGS. ~ Photoetching having a Pt plating layer 23 rather than using a Pt plating layer 23 on the surface of the photoetching titanium mesh 24 as in the third water electrolysis devices 10E to 10G according to the third embodiment shown in Fig. 7. Similar to the power supply body 14B made of the titanium mesh 24, the contact area between the catalyst surface of the catalyst layer and the Pt vapor deposition layer 26 is increased, and the electron conductivity can be ensured. Therefore, the amount of Pt used per unit area of the water electrolysis cell 15 can be greatly reduced, and even when the amount of Pt particles is reduced, the water electrolysis performance equivalent to that of the conventional water electrolysis apparatus 100 as shown in FIG. Can be obtained.

  Further, the thickness of the Pt vapor deposition layer 26 is preferably about 0.1 μm to 0.5 μm, and practically about 0.2 μm. In terms of cost, the thinner the film thickness, the lower the amount of platinum used, which is advantageous in terms of cost. However, in the vapor deposition method, a pinhole (unplated portion) is present at a thickness of 0.1 μm or less. This is because it tends to occur.

FIG. 9 is a conceptual diagram schematically showing another configuration of the water electrolysis apparatus according to the present embodiment. Like the fourth water electrolysis apparatus 10I according to the present embodiment shown in FIG. 9, the water electrolysis cell having the oxygen electrode catalyst layer 13D made of only the high specific surface area IrO ₂ particles 25 without adding the Pt black particles 19 15I may be used.

  Therefore, according to the fourth water electrolysis apparatuses 10H and 10I according to the present embodiment shown in FIGS. 8 and 9, by having the power supply body 14C made of the photoetched titanium mesh 24 having the Pt vapor deposition layer 26 on the surface, The amount of Pt used per unit area of the water electrolysis cell 15 can be significantly reduced, and even if the amount of Pt used is reduced, a water electrolysis reaction equivalent to the conventional one can be made possible.

  Examples illustrating the effects of the present invention will be described below, but the present invention is not limited thereto.

  The water electrolysis performance (energy efficiency) of the water electrolysis cell of the water electrolysis apparatus according to the present embodiment will be verified.

[How to make a water electrolysis cell]

First, a method for producing a water electrolysis cell used in this example will be described.
A polymer electrolyte membrane (trade name) prepared on a superheated suction stand by preparing a slurry for a hydrogen electrode and a slurry for an oxygen electrode in which a catalyst, a polymer electrolyte solution, and a water repellent material (binder) are dispersed in an ethanol solution : Nafion film) was uniformly applied by a spray coating method on each side. The cell with the catalyst layer coated on both sides was dried at about 80 ° C. for a predetermined time, and then hot pressed at a predetermined temperature and a predetermined pressure for about 1 minute to obtain a uniform cell. Thereafter, the cell was boiled and washed at about 100 ° C. for a predetermined time to obtain a water electrolysis cell.

A method for producing a water electrolysis cell used in Example 1 will be specifically described.
1.5 g of platinum black, 0.5 g of platinum-supported carbon (platinum 66.8 wt% carbon-supported catalyst), and 0.37 g of PTFE powder as a water repellent were weighed and placed in an approximately 100 cc glass container. Then, 15.8 ml of 5 wt% Nafion solution (manufactured by DuPont) and 68 ml of ethanol were added, and ultrasonic dispersion was performed for 5 minutes to obtain a slurry for spray coating for the hydrogen electrode catalyst layer.
Also, 3.0 g of platinum black, 3.7 g of iridium oxide, and 0.48 g of PTFE powder as a water repellent agent are weighed and placed in an approximately 100 cc glass container, and then 25.2 ml of 5 wt% Nafion solution and 90 ml of ethanol are added. Then, ultrasonic dispersion was performed for 5 minutes to obtain a slurry for spray coating for the oxygen electrode catalyst.
Then, the Nafion membrane cut out to a predetermined size is placed on the suction type superheater of the porous plate plate, and while maintaining the plate surface temperature at 80 ° C., using the automatic spray coating device, the oxygen electrode side and the negative electrode side are sequentially ordered Each of the slurries prepared as described above was applied by spraying to form a catalyst layer.
Also, the water electrolysis cell with the catalyst layer applied on both sides of the Nafion membrane is dried at 80 ° C for 1 hour and then stored in a constant temperature bath at about 30 ° C to confirm that the weight is constant (the weight does not change). Used after.
Then, the prepared water electrolysis cell is sandwiched between PTFE plates having a thickness of about 2 mm, both sides are sandwiched between stainless plates having a thickness of 1 mm, and pressed at a surface pressure of 10 kgf / cm ² , and the temperature is increased to 160 ° C. Thereafter, it was held for 1 minute and hot pressed. Thereafter, the prepared water electrolysis cell was immersed in ion-exchanged water at room temperature for about 8 hours or more, then boiled to about 100 ° C., held for about 1 hour, and cooled to perform a washing treatment.

  Regarding the methods for preparing the water electrolysis cells used in Comparative Examples 1 and 2 and Examples 2 to 11, slurries were prepared in the same manner as in Example 1, and the water electrolysis cells were similarly formed by spray coating. Created.

  Table 1 below shows the results of summarizing the types of materials and the amounts used in the hydrogen electrode catalyst layer and the oxygen electrode catalyst layer of the water electrolysis cell prepared as described above.

  Also, the amount of hydrogen electrode platinum used between the hydrogen electrode catalyst layer and the power feeder of the water electrolysis cell prepared as described above, the amount of oxygen electrode platinum used between the oxygen electrode catalyst layer and the power feeder, the iridium oxide specific surface area, the power supply The results of summarizing the body types are shown in Table 2 below.

[Verification of water electrolysis performance (energy efficiency) of Examples 1 to 4 and Comparative Example 1]
Example 1 to Example 4 using the water electrolysis cell according to the first embodiment of the present invention and the water electrolysis cell of the water electrolysis device according to the third embodiment, and conventional water as shown in FIG. Electrolytic performance (energy efficiency) was verified for Comparative Example 1 using the water electrolysis cell 101 of the electrolysis apparatus 100.

[Evaluation method of water electrolysis cell]
A method for evaluating the water electrolysis cell will be described. A titanium mesh plated with Pt as a power feeding body was sandwiched from both electrode sides to form a water electrolysis cell. Thereafter, pure water was supplied, and the voltage, amount of generated gas, and impurity concentration when a predetermined current was passed were measured, and electrolysis performance (energy efficiency) was determined from the current efficiency and voltage efficiency.

  Example 1 to Example 4 used in the water electrolysis cell of the water electrolysis apparatus according to the first embodiment and the third embodiment of the present invention, and water electrolysis of a conventional water electrolysis apparatus 100 as shown in FIG. Table 2 shows the electrolytic performance (energy efficiency) of Comparative Example 1 used in the cell.

[Water electrolysis performance (energy efficiency) of Examples 1 to 4 and Comparative Example 1]
FIG. 10 is a graph showing the relationship between the total platinum loading of the hydrogen electrode catalyst layer and the energy efficiency. As shown in Table 2 and FIG. 10, Examples 1 to 4 using water electrolysis cells of the water electrolysis apparatus according to the first embodiment of the present invention and the water electrolysis apparatus according to the third embodiment. Although the total amount of platinum supported by the hydrogen electrode catalyst layer of this example is smaller than the total amount of platinum supported by the hydrogen electrode catalyst layer 104 of Comparative Example 1 using the conventional water electrolysis apparatus 100 as shown in FIG. Example 1 to Example 4 using the water electrolysis cell of the water electrolysis apparatus according to the first embodiment of the invention and the water electrolysis apparatus according to the third embodiment are more conventional as shown in FIG. The electrolytic performance (energy efficiency) was higher or equivalent to that of Comparative Example 1 using the water electrolysis apparatus 100.

  Therefore, by using a mixture of Pt black particles and a Pt-supported carbon catalyst for the hydrogen electrode catalyst layer, and using iridium oxide particles having a high specific surface area for the oxygen electrode catalyst layer, Even when the amount of Pt black particles used was reduced, it was confirmed that the water electrolysis performance was equal to or higher than that of the conventional one.

[Water electrolysis performance (energy efficiency) of Examples 5 to 8]
The water electrolysis performance of Examples 5 to 8 using the water electrolysis apparatus according to the second embodiment and the third embodiment of the present invention will be described.
Hydrogen electrode platinum usage amount of oxygen electrode catalyst layer, oxygen electrode catalyst of Example 5 to Example 8 using water electrolysis cell of water electrolysis apparatus according to second embodiment and third embodiment of present invention Table above shows the amount of oxygen electrode platinum used in the layer, the total amount of platinum supported by the total amount of platinum supported by the hydrogen electrode catalyst layer and the oxygen electrode catalyst layer, the type of power supply, and the electrolysis performance (energy efficiency) of the water electrolysis cell It is shown in 2.

  FIG. 11 is a diagram showing the relationship between the total platinum carrying amount of both electrodes of the water electrolysis apparatus and the energy efficiency. As shown in Table 2 and FIG. 11, Examples 5 to 8 using water electrolysis cells of the water electrolysis device according to the second embodiment of the present invention and the water electrolysis device according to the third embodiment. The bipolar electrode of Examples 1 to 4 using the water electrolysis cell of the water electrolysis apparatus according to the first embodiment of the present invention and the water electrolysis apparatus according to the third embodiment of the present invention. Despite being less than the total platinum loading, the electrolysis performance (energy efficiency) of the water electrolysis cell was almost the same.

  Moreover, even if compared with the comparative example 1 using the water electrolysis cell of the conventional water electrolysis apparatus 100 as shown in FIG. Despite being less than the total amount of platinum supported on both electrodes, Examples 5 to 8 have an electrolytic performance (energy efficiency) of Comparative Example 1 using the conventional water electrolysis apparatus 100 as shown in FIG. It was almost the same.

Therefore, by using a power feeder made of a photoetched titanium mesh having a Pt plating layer on the surface, using only a Pt-supported carbon catalyst for the hydrogen electrode catalyst layer, and using high specific surface area IrO ₂ particles for the oxygen electrode catalyst layer. Even if no Pt black particles are added to the hydrogen electrode catalyst layer, water electrolysis performance equivalent to the conventional one can be obtained.

[Effect of specific surface area of high specific surface area IrO ₂ particles on water electrolysis performance (energy efficiency)]
The water electrolysis performance of the water electrolysis cell using the high specific surface area IrO ₂ particles having different specific surface areas will be described.
Examples 5 and 6, with a high specific surface area IrO ₂ particles having a specific surface area of about 60 m ² / g, Example 7 and 8, a specific surface area using a high specific surface area IrO ₂ particles of about 112m ² / g Is.
In Comparative Example 2, IrO ₂ particles having a specific surface area of about 1.0 m ² / g were used for the hydrogen electrode catalyst layer.

The specific surface areas of the IrO ₂ particles of Examples 5 and 6 are shown in Table 2 above.
Also, the amount of platinum used in the hydrogen electrode catalyst layer of the water electrolysis cell of Comparative Example 2 of the water electrolysis apparatus using IrO ₂ particles having a specific surface area of about 1.0 m ² / g as the hydrogen electrode catalyst layer and the power feeder Table 2 shows the amount of platinum used for the oxygen electrode in the oxygen electrode catalyst layer and the power feeder, the specific surface area of IrO ₂ particles, the type of the power feeder, and the electrolysis performance (energy efficiency) of the water electrolysis cell.

FIG. 12 is a diagram showing the relationship between the specific surface area of iridium oxide particles and energy efficiency. As shown in Table 2 and FIG. 12, Examples 5 to 8 using high specific surface area IrO ₂ particles in the hydrogen electrode catalyst layer were more effective than IrO ₂ particles having a specific surface area of about 1.0 m ² / g. Compared to Comparative Example 2 using the hydrogen electrode catalyst layer, the water electrolysis performance could be greatly improved.

Therefore, by using IrO ₂ particles with a high specific surface area for the oxygen electrode catalyst layer and making them finer to the nano level than the conventionally used IrO ₂ particles, the water electrolysis performance can be greatly improved than before. it can.

[Water electrolysis performance (energy efficiency) of Examples 9 to 11]
The water electrolysis performance of Examples 9 to 11 using the water electrolysis apparatus according to the fourth embodiment of the present invention will be described.
Example 9 to Example 11 using the water electrolysis cell of the water electrolysis apparatus according to the fourth embodiment of the present invention, the total amount of platinum supported on the hydrogen electrode catalyst layer, the amount of power supply platinum plating used, the oxygen electrode catalyst layer Table 2 shows the total platinum loading amount, the power supply platinum plating usage amount, the bipolar electrode total platinum loading amount, the bipolar electrode total platinum usage amount, the type of the power feeding body, and the electrolysis performance (energy efficiency) of the water electrolysis cell.
The total amount of platinum used for both electrodes is the sum of the total amount of platinum supported by both electrodes and the total amount of platinum supported by both electrodes.

  FIG. 13 is a diagram showing the relationship between the total platinum usage of both electrodes of the water electrolysis apparatus and the energy efficiency. As shown in Table 2 and FIG. 13, the total amount of platinum used in Examples 9 to 11 using the water electrolysis cell of the water electrolysis apparatus according to the fourth embodiment of the present invention is the same as in FIG. 5. The electrolysis performance (energy efficiency) of the water electrolysis cell was significantly smaller than the total amount of platinum used in Examples 7 and 8 using the third water electrolysis apparatus 10E according to the third embodiment shown in FIG. ) Was almost equivalent.

  Moreover, even if compared with the comparative example 1 using the water electrolysis cell of the conventional water electrolysis apparatus 100 as shown in FIG. 14, the direction of the total amount of platinum used in Examples 9 to 11 is greater in FIG. The electrolysis performance (energy efficiency) of the water electrolysis cell is substantially the same or higher in spite of being significantly smaller than the total amount of platinum used in Comparative Examples 1 and 2 using the conventional water electrolysis apparatus 100 as shown. there were.

Therefore, by using a power feeder made of a photoetching titanium mesh having a Pt vapor deposition layer on the surface, using only a Pt-supported carbon catalyst for the hydrogen electrode catalyst layer, and using high specific surface area IrO ₂ particles for the oxygen electrode catalyst layer. In addition, the amount of Pt used per unit area of the water electrolysis cell can be greatly reduced, and water electrolysis performance substantially equivalent to that of the prior art can be obtained without adding Pt black particles to the catalyst layer.

  As described above, the water electrolysis apparatus according to the present invention can perform the same water electrolysis reaction as before while reducing the amount of Pt used in the water electrolysis cell, and improve the water electrolysis performance while reducing the cost. Therefore, it is suitable for use in a water electrolysis apparatus that electrolyzes water to generate hydrogen.

It is the schematic which shows simply the structure of the water electrolysis apparatus which concerns on 1st embodiment by this invention. It is a conceptual diagram which shows simply the structure of the water electrolysis apparatus which concerns on 2nd embodiment by this invention. It is a conceptual diagram which shows simply the other structure of the water electrolysis apparatus which concerns on 2nd embodiment by this invention. It is a conceptual diagram which shows simply the other structure of the water electrolysis apparatus which concerns on 2nd embodiment by this invention. It is a conceptual diagram which shows simply the structure of the water electrolysis apparatus which concerns on 3rd embodiment by this invention. It is a conceptual diagram which shows simply the other structure of the water electrolysis apparatus which concerns on 3rd embodiment by this invention. It is a conceptual diagram which shows simply the other structure of the water electrolysis apparatus which concerns on 3rd embodiment by this invention. It is a conceptual diagram which shows simply the structure of the water electrolysis apparatus which concerns on 4th embodiment by this invention. It is a conceptual diagram which shows simply the other structure of the water electrolysis apparatus which concerns on 4th embodiment by this invention. It is the figure which showed the relationship between the total amount of platinum carrying | support of a hydrogen-electrode catalyst layer, and energy efficiency. It is the figure which showed the relationship between both electrode total platinum carrying | support amount of a water electrolysis apparatus, and energy efficiency. It is the figure which showed the relationship between the specific surface area of iridium oxide particle | grains, and energy efficiency. It is the figure which showed the relationship between both electrode total platinum usage-amount of a water electrolysis apparatus, and energy efficiency. It is a figure which shows an example of the conventional water electrolysis apparatus.

Explanation of symbols

10A First water electrolysis device 10B to 10D Second water electrolysis device 10E to 10G Third water electrolysis device 10H, 10I Fourth water electrolysis device 11 Polymer solid electrolyte membrane 12A, 12B Hydrogen electrode catalyst layer 13A to 13C Oxygen electrode catalyst layer 14A-14C Power supply 15A-15I Water electrolysis cell 16 Separator plate 17 Pt-supported carbon catalyst 18 Rubber packing 19 Pt black particles 20 Iridium oxide (IrO ₂ ) particles 21 Polymer electrolyte solution 22 Water repellent 23 Pt Plating layer 24 Photoetching titanium mesh 25 High specific surface area iridium oxide (IrO ₂ ) particles 26 Pt vapor deposition layer

Claims (6)

The hydrogen electrode catalyst layer and the oxygen electrode catalyst layer are provided with a hydrogen electrode catalyst layer and an oxygen electrode catalyst layer on both sides of the polymer solid electrolyte membrane, and a power feeding body for supplying power to the hydrogen electrode catalyst layer and the oxygen electrode catalyst layer. In a water electrolysis apparatus provided with water electrolysis cells each arranged on the outside of
A water electrolysis apparatus, wherein the hydrogen electrode catalyst layer includes a platinum-supported carbon catalyst supporting platinum particles. In claim 1,
The water electrolysis apparatus, wherein the hydrogen electrode catalyst layer is a mixture of the platinum-supported carbon catalyst and platinum black particles. In claim 1 or 2,
The water electrolysis apparatus, wherein the oxygen electrode catalyst layer is composed of a mixture of platinum black particles and iridium oxide particles, or composed of only the iridium oxide particles. In any one of Claims 1 thru | or 3,
The water feeder is any one of a titanium mesh plated with platinum, a photo-etched titanium mesh having a platinum-plated layer, and a photo-etched titanium mesh having a platinum-deposited platinum layer on the surface. . In claim 3 or 4,
A water electrolysis apparatus, wherein the iridium oxide particles are high specific surface area iridium oxide particles having a specific surface area of 50 m ² / g or more. In any one of Claims 1 thru | or 5,
A water electrolysis apparatus comprising a plurality of stacked water electrolysis cells sandwiched between a plurality of separator plates to constitute a cell stack.

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