JP2019031702A - Electrode for electrolyzing water, and method of producing the electrode - Google Patents

Abstract

To provide a basic constitution of an electrode for electrolyzing water, capable of performing efficient electrolysis based on the catalytic function of a carbon nanotube, and a basic constitution of producing the electrode.SOLUTION: There is provided an electrode 1 for use in electrolyzing water, which is characterized in that a film 12 of carbon nanotubes are formed on the surface of a titanium substrate 11. There is provided a method of producing the electrode by applying an electric field of not lower than 1000 V/mm between a cathode of the titanium substrate 11 and an anode of the titanium substrate 11 or of another electroconductive material in an atmosphere in which carbon particles of a particle diameter of not greater than 2 μm are distributed, or by carrying out arc discharge by applying a pulse voltage of a time width of not greater than 1 ms to a carbon anode and a cathode of the titanium substrate 11 disposed in a heated chamber filled with an inert gas, to solve the problem described above.SELECTED DRAWING: Figure 1

Description

  The technical field of the present invention is an electrode used for electrolysis into hydrogen and oxygen by applying a DC voltage to water and a method for producing the electrode.

  As a configuration of an electrode used when electrolyzing water, it is already a well-known technical matter to form a catalyst layer on the surface of a predetermined substrate.

  As such a laminated structure of the base material + catalyst layer, for example, Patent Document 1 proposes a structure in which a carbon film is deposited on a porous base material such as titanium (Ti) mesh (paragraph [0059]). .

  However, in such a configuration, the amount of oxygen and hydrogen generated with respect to the applied electric power is small, and efficient electrolysis is not sufficiently realized. Moreover, in order to deposit the carbon film, the ECR plasma deposition method is used. It is necessary to adopt this, and the manufacturing process is complicated.

  Patent Document 2 proposes a structure in which a catalyst layer of iridium (Ir) is formed on both surfaces of a titanium base material (claim 4).

  However, in the case of the above-described configuration, there is a drawback that efficient electrolysis is not sufficient, and the technical problem of heat generation in the electrodes and water cannot be solved.

  In recent years, carbon nanotubes have the feature that they have flexibility and physical strength while being able to set conductivity similar to that of metals, and are used as materials in various electronic fields. ing.

  In Patent Document 3, after paying attention to the structure in which carbon nanotubes have voids, the structure of an electrode cured by an adhesive made of a thermosetting resin in which carbon nanotubes are mixed at 10% to 50% on a substrate made of carbon fiber. Compared with the case of patent document 2, the electrolysis efficiency of the carbon nanotube is implement | achieved by the catalytic function in the electrolysis of a carbon nanotube.

  However, while the composition of the thermosetting resin is a factor that lowers the conductivity, the above configuration is the first step for producing an adhesive for the thermosetting resin by mixing carbon nanotubes, and the adhesion to the carbon fiber. 2nd process of impregnating and coating agent, 3rd process of solidifying carbon fiber by infrared irradiation, 4th process of completely carbonizing and curing carbon fiber by heating and pressing, complicated manufacturing process Is essential.

  Thus, the electrode for water electrolysis according to the prior art is not always sufficient in electrolysis efficiency, and technical disadvantages cannot be avoided in other matters.

JP 2004-18982 A JP 2012-122383 A JP 2016-37662 A

  An object of the present invention is to provide a basic configuration of an electrode for water electrolysis that enables efficient electrolysis and a basic configuration for manufacturing the electrode, focusing on the catalytic function in the electrolysis of carbon nanotubes It is said.

In order to solve the above problems, the basic configuration of the present invention is as follows.
(1) A water electrolysis electrode characterized by forming a film of carbon nanotubes on a titanium-based surface;
(2) In the air in which carbon particles having a particle size of 2 μm or less are distributed, a titanium substrate is selected as a cathode, and an electric field of 1000 V / mm or more is applied between the two electrodes, thereby providing a titanium substrate. A method of producing an electrode according to (1), wherein a film of carbon nanotubes is formed on the surface of
(3) In a room set with carbon as an anode and a titanium substrate as a cathode, filled with an inert gas, set to a temperature of 1000 ° C. or higher and less than 1660 ° C., which is the melting temperature of titanium. The method for producing an electrode according to (1), wherein the carbon nanotube film is formed on the surface of the titanium base material by pulse arc discharge based on application of a pulse voltage with a time width of 1 ms or less, or by repeating the discharge. ,
Consists of.

  The electrode based on the basic configuration (1) can exhibit better energy conversion efficiency than the electrode in which carbon fibers and carbon nanotubes described in Patent Document 2 are bonded via a heat-permeable resin. In the manufacturing methods based on the basic configurations (2) and (3), the electrodes having the basic configuration (1) can be formed by a simple method of applying a DC voltage.

It is sectional drawing of the electrode of basic composition (1). It is a graph which shows contrast of embodiment of basic composition (1), and electrolysis efficiency by patent documents 2 and the prior art of the same. It is a side view of the electrolysis tank which arranged the electrode which combined the electrode of basic composition (1). It is a side view which shows the manufacturing method of basic composition (2). It is a side view which shows the manufacturing method of basic composition (3).

  As shown in FIG. 1, the electrode 1 having the basic configuration (1) has a carbon nanotube film 12 formed on both sides of a titanium substrate 11.

  The thickness of the film 12 is usually set to 6 μm or more, but the ground is that if it is less than 6 μm, the catalytic function in the electrolysis of the carbon nanotubes cannot be sufficiently exhibited.

  The upper limit of the film 12 is not particularly limited, but usually it is often set to 12 μm or less in consideration of the production cost and the saturated state of the catalytic function by the carbon nanotube film 12.

  As shown in FIG. 1, the titanium base material 11 is usually plate-shaped in many cases, but is not necessarily limited to such a shape. For example, other forms such as a cylindrical shape may be adopted. it can.

  As an electrode having a rectangular shape of 10 cm × 18 cm and a thickness of 0.5 mm, an electrode 1 in which both sides of a titanium substrate 11 are covered with 7 μm carbon nanotubes based on the basic configuration (1), as in Patent Document 3 An electrode in which carbon fibers and carbon nanotubes are bonded by an adhesive made of a thermosetting resin, and the carbon nanotubes are mixed in the thermosetting resin by 10%, as in Patent Document 2, the surface of the titanium substrate 11 When the electrodes covered with iridium having a thickness of 0.3 mm are adopted on both sides of the electrode, the distance between the electrodes is set to 1.5 mm in water, and the applied power is changed sequentially, the HHO gas The change in the generation amount is shown in the graph of FIG.

  As shown in FIG. 2, the electrode 1 of the basic configuration (1) has an applied power of 60 W, for example, 1800 cc / percent compared to an electrode formed by combining carbon fibers and carbon nanotubes as in Patent Document 3. The electrolysis efficiency is 800 cc = 2.25 times, and the electrolysis efficiency is 1800 cc / 300 cc = 6 times that of the structure in which the titanium substrate 11 is coated with iridium as in Patent Document 2.

Thus, in the basic configuration (1), the reason why good electrolysis efficiency is obtained is that the carbon nanotube forms a tube by forming the carbon nanotube film 12 on the surface of the titanium base material 11 as a catalyst layer. It is considered that the opportunity to perform the cathode reaction and anode reaction of water in the pipe-shaped space is improved.
However, there is no other reason for such good electrolysis efficiency than waiting for analysis with various future experiments and consideration based on the analysis.

In the manufacturing method of the basic configuration (2), as shown in FIG. 4, after selecting the titanium base material 11 as a cathode in the air in which carbon particles having a particle size of 2 μm or less are distributed, between the two electrodes The electrode 1 having the basic configuration (1) is manufactured by forming a film 12 having a carbon nanotube as a catalyst layer on the cathode made of the titanium substrate 11 by applying an electric field of 1000 V / mm or more (see FIG. 4 shows a case where the carbon nanotube film 12 is formed on one side of the cathode of the titanium base material 11, but the formation of the film 12 on the other side is realized by reversing the direction of the electrodes. Can do that.)
Of the two electrodes, for the anode, a titanium base material 11 or a conductive material other than the base material can be employed.

The diameter of the carbon nanotube by stacking the graphite-like carbon is 2 to 50 nm and the length is about 1 to 10 μm, but the basic structure (2) using carbon particles having a diameter of 2 μm or less as a raw material, As a basis for the formation of carbon nanotubes, the carbon particles move to the cathode by an electric field of 1000 V / mm or more, while the electrons flowing out of the cathode are accelerated by the electric field, and as a result of collision with the carbon particles, It is considered that the carbon particles are subdivided along the moving direction of the electrons and are stretched in the moving direction in a state where a tube-like void is generated.
However, the detailed grounds that accompany the quantitative analysis can only be awaited by analysis based on future experiments and considerations involving such analysis.
Incidentally, the fact that carbon nanotubes are generated from carbon particles having a diameter of 2 μm or less is that the electrical conductivity of the coating formed by the basic configuration (2) is orders of magnitude higher than the electrical conductivity of the carbon particles. It can be confirmed by being large.

  The distribution of carbon particles having a diameter of 2 μm or less does not exclude the presence of carbon particles having a diameter larger than 2 μm and other particles.

  This is because even if these particles are present, a coating 12 made of carbon nanotubes is formed on the surface of the titanium substrate 11 by the movement of carbon particles having a diameter of 2 μm or less to the cathode by the titanium substrate 11. This is because there is no change.

The diameter of carbon particles in the smoke when coal is burned is usually about 1 μm.
Therefore, carbon particles having a diameter of 2 μm or less can be easily distributed in the air in the space where the smoke generated when coal is burned is distributed.

  As described above, as long as the existence of a distribution of other particles other than carbon particles having a diameter of 2 μm or less is allowed, not only soot based on the combustion of coal but also combustion of other carbon-containing materials (for example, combustion of wood) ), The manufacturing method of the basic configuration (2) can be realized.

  However, in the case of the same electric field, in consideration of the fact that carbon particles with a diameter of 2 μm or less move more easily than other particles, in the case of forming smoke by burning other carbon-containing materials, In order to prevent arrival of the titanium base material 11 by other particles at the cathode, it is necessary to set the electric field so that the magnitude of the electric field does not significantly exceed 1000 V / mm.

  It is a well-known technical matter to form a carbon nanotube on the cathode side by realizing an arc discharge between an anode and a cathode made of carbon.

However, in the case of a normal arc discharge, a high temperature of 3000 K or more is formed in the region where the discharge is performed, which exceeds the melting temperature of 1660 ° C. of titanium.
Therefore, even if normal arc discharge is performed by using carbon as an anode and a titanium substrate as a cathode, the titanium substrate is dissolved and a carbon nanotube film is formed on the surface of the substrate in a stable state. It is difficult to form.

  Considering the difficulty in adopting such normal arc discharge, in the basic configuration (3), as shown in FIG. 5, carbon is used as the anode 3 and the titanium substrate 11 is used as the cathode. Pulsed arc discharge based on application of a pulse voltage with a time width of 1 ms or less in a room filled with active gas and set to a temperature of 1000 ° C. or higher and lower than 1660 ° C. which is the melting temperature of titanium, or The electrode 1 having the basic structure (1) is manufactured by forming the carbon nanotube film 12 on the surface of the titanium base material 11 by repeating the discharge (in FIG. 5, the cathode of the titanium base material 11 is also formed). Although the case where the carbon nanotube film 12 is formed on one side is shown, the formation of the film 12 on the other side is realized by reversing the direction of the electrodes. It is.).

  In the case of such a pulse arc discharge, the discharge time is an extremely short time of 1 ms or less, so even if the melting temperature of titanium is instantaneously higher than 1660 ° C., the titanium does not dissolve, The carbon nanotube film 12 can be formed on the surface of the titanium substrate 11 in a stable state.

In addition, as shown in FIG. 5, since the periphery of the electrode is heated in a temperature range of 1200 ° C. to 1660 ° C., the effect of so-called thermal convection as in normal arc discharge can be suppressed.
In the basic configuration (2), the pulse arc discharge is not only repeated once but also when the discharge is repeated. The thickness of the carbon nanotube film formed by the arc discharge per one time is thin and the catalytic function is 6 μm. The purpose is to realize a preferable thickness for exhibiting the above.

  The reason why the carbon nanotube film 12 is formed by the pulsed arc discharge is based on the assumption that the carbon particles scattered from the carbon electrode collide with thermal electrons generated from titanium which is a cathode, thereby forming a tube-shaped void. can do.

  The amount of current in realizing pulsed arc discharge depends on the surface areas of the cathode and anode and cannot be specified uniformly.

  On the other hand, the inventors' experience has shown that the necessary and appropriate applied voltage is 2000V to 3000V when the distance between the anode and the cathode is 1 mm.

  In the example, as shown in FIG. 3, the electrodes 1 of the basic configuration (1) constituting the anode and the electrodes 1 of the basic configuration (1) forming the cathode were arranged in an alternately adjacent state. It is characterized by an electrolysis tank 4 in which a coupling electrode is provided.

  In such a coupled electrode, a DC voltage is applied between each anode and each cathode, and oxygen molecules are introduced on the anode side in a state where the carbon nanotube films 12 forming the anode and the cathode face each other. Oxygen hydrogen gas (HHO gas) can be efficiently generated by generating and generating hydrogen molecules on the cathode side.

  Thus, in the present invention, an electrode having extremely good electrolysis efficiency can be provided by a very simple manufacturing method.

  As a result, it is possible to quickly improve the combustion efficiency by efficiently forming oxygen-hydrogen gas (HHO gas) and injecting it into the combustion portion of the internal combustion engine.

Furthermore, in the combustion of general organic matter, efficient combustion is realized by supplying oxygen molecules based on electrolysis using the electrode according to the present invention, while carbon dioxide (CO ₂ gas) accompanying combustion is intervened by intervening hydrogen molecules. It is possible to efficiently realize combustion in a state where the occurrence of) is prevented or reduced.

  As described above, the present invention has various advantages, and can be widely used.

DESCRIPTION OF SYMBOLS 1 Electrode 11 of basic composition (1) Titanium base material 12 Coating by carbon nanotube 2 Carbon anode adopted in basic composition (2) 3 Carbon anode adopted in basic composition (3) 4 Electrolysis tank 5 Pulse voltage Source 6 Chamber for pulse arc discharge 7 Heater

Claims (8)

  An electrode for water electrolysis in which a carbon nanotube film is formed on a titanium-based surface.   2. The electrode according to claim 1, wherein the thickness of the coating is 6 [mu] m or more.   An electrolytic cell in which a combined electrode is provided in which the electrode according to claim 1 constituting the anode and the electrode according to claim 1 forming the cathode are alternately arranged adjacent to each other.   In the air in which carbon particles having a particle size of 2 μm or less are distributed, a titanium base material is selected as a cathode, and an electric field of 1000 V / mm or more is applied between the two electrodes, thereby causing the surface of the titanium base material to be applied. The method for producing an electrode according to claim 1, wherein a film of carbon nanotubes is formed.   The production method according to claim 4, wherein a distribution state of carbon particles of 2 μm or less is realized in the air by soot generated by burning coal.   1 ms or less in a room filled with an inert gas and set at a temperature of 1000 ° C. or higher and less than 1660 ° C., which is the melting temperature of titanium, using carbon as an anode and a titanium substrate as a cathode 2. The method for producing an electrode according to claim 1, wherein the carbon nanotube film is formed on the surface of the titanium substrate by pulsed arc discharge based on application of a pulse voltage with a time width of, or by repeating the discharge.   The manufacturing method according to claim 6, wherein a peak value of the pulse application voltage is in a range of 2000V to 3000V.   4. The electrolytic cell according to claim 3, wherein a direct current voltage is applied between each anode and each cathode, and the carbon nanotube films forming the anode and the cathode face each other with oxygen on the anode side. A method of generating HHO gas by generating molecules and generating hydrogen molecules on the cathode side.

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