Hydrogen supply system for generating a hydrogen gas from an electrolyte water by water splitting

Abstract

This is a system for generating and supplying a hydrogen gas from water by water splitting using a carbon electrode containing ethylidyne without any external electric power, which system comprises A) a carbon electrode containing ethylidyne, B) an alkaline electrolyte water solution and C) a metal electrode selected from group consisting of a typical metal including zinc, aluminum and magnesium and a transition metal including copper, wherein the carbon electrode containing ethylidyne and the metal electrode are brought into contact with or opposed to each other in the alkaline electrolyte water solution, and the water is decomposed by the effect of ethylidyne to generate a hydrogen gas according to the following reaction.

CH.sub.3C+O.fwdarw.CH.sub.3CO.sup.++e−

2H.sup.++2e−.fwdarw.H.sub.2↑

as shown in FIG. 1A

Claims

1. A hydrogen gas supply system for generating a hydrogen gas from water by water splitting, which comprises A) a carbon electrode containing ethylidyne, B) an alkaline electrolyte water solution and C) a metal electrode capable to be ionized in the alkaline electrolyte water solution and selected from group consisting of a typical metal including zinc, aluminum and magnesium and a transition metal including copper, wherein the carbon electrode and the metal electrode are not connected with any external circuit, and wherein the hydrogen gas is generated due to water splitting according to a redox reaction of the following reaction.
CH.sub.3C+O.fwdarw.CH.sub.3CO.sup.++e.sup.−, 2H.sup.++2e.sup.−.fwdarw.H.sub.2↑

2. The hydrogen gas supply system according to claim 1, wherein the alkaline electrolyte water solution is configured by adding 5 to 30 volume %, preferably 15 to 20 volume % of a 50% caustic soda solution to the electrolyte water solution.

3. The hydrogen gas supply system according to claim 2, wherein a sea water is used as the electrolyte water solution.

4. The hydrogen supply system according to claim 1 wherein the carbon electrode containing ethylidyne can be made from a graphite having a sp2 carbon structure and a sp3 carbon structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1A is a schematic diagram of a hydrogen supply system according to the present invention, showing a state in which a 3 mm thick Al metal plate and a carbon electrode expanded to a thickness of 15 mm are combined and put into a saline solution to which 20% by volume of 50% caustic soda solution is added;

[0026] FIG. 1B is a photograph of the hydrogen generation of the hydrogen supplying system of FIG. 1A.

[0027] FIG. 2A is a photograph showing the hydrogen evolution state in water from the carbon electrode according to the present invention.

[0028] FIG. 2B is a photograph showing a hydrogen evolution state from the ethylidyne metal complex formed by ethylidyne released into water from the carbon electrode according to the present invention adheres to the electrode.

[0029] FIG. 3 is a schematic diagram of a hydrogen microscopy TOF-ESD device for detecting ethylidyne in a carbon electrode according to the present invention.

[0030] FIG. 4A is a hydrogen analysis of the unused carbon electrode sample (10 mm×8 mm), it is a photograph of a state of being set in a sample holder with a heater for heating.

[0031] FIG. 4B is also a hydrogen analysis of the carbon electrode sample (10 mm×8 mm) after water electrolysis, it is a photograph of a state set in the sample holder with a heater for heating.

[0032] FIG. 5A shows the temperature rise desorption spectrum of impurities emitted from the sample surface into the vacuum at heating up to a sample temperature of 200° C.

[0033] FIG. 5B shows the temperature rise desorption spectrum of impurities emitted from the sample surface into the vacuum at heating up to a sample temperature of 290° C.

[0034] FIG. 6A shows the temperature rise desorption spectrum of the sample temperature of 290° C. wherein the test was repeated six times, and the temperature rise desorption spectrum of the third time is shown.

[0035] FIG. 6B shows the temperature rise desorption spectrum of the sample temperature of 290° C. wherein the test was repeated six times, and the temperature rise desorption spectrum of the fourth time is shown.

[0036] FIG. 6C shows the temperature rise desorption spectrum of the sample temperature of 290° C. wherein the test was repeated six times, and the temperature rise desorption spectrum of the sixth time is shown.

[0037] FIG. 7 shows a conceptual diagram showing a condition in which electrons are pulled out from the oxygen by Na.sup.+ in the swelling FGS.

[0038] FIG. 8 is a conceptual diagram of a microcell and microcapacitor metal ions are formed in the swelled FGS.

[0039] FIG. 9 is an EDS elemental component table of a carbon electrode obtained by electrolysis in saline.

[0040] FIG. 10 shows photomicrographs (a), (b), (c) and (d) of a carbon electrode hydrogen-occluded by water electrolysis process.

[0041] FIG. 11 is a photomicrograph and EDS elemental component table when a carbon electrode that has been hydrogen-occluded by a water splitting power generation treatment in brine is subjected to a swelling treatment.

[0042] FIG. 12A is a graph showing a microscopic Raman spectrum of the carbon electrode before the swelling treatment (A).

[0043] FIG. 12B is a graph showing a microscopic Raman spectrum of the carbon electrode after the swelling treatment (B).

[0044] FIG. 12C is a graph showing a microscopic Raman spectrum of the carbon electrode after the concentrated nitric acid immersion treatment (C).

EMBODIMENT FOR CARRYING OUT THE INVENTION

[0045] (Production of Carbon Electrodes Containing Ethylidyne)

[0046] As shown in FIG. 10, in the carbon electrode according to the present invention, it is necessary to constitute a microcell with a graphite layer serving as a counter electrode by penetration of metal ions and to constitute a micro capacitor between adjacent graphite layers in the carbon electrode. Therefore, the graphite sheet is immersed in water or the like overnight and expanded by flame heating of a burner or the like. To facilitate flame expansion, immersion solutions are prepared by dissolving 50 ml concentrated nitric acid, 0.5-1.0 mol glucose, NaCl; 1.0-1.5 mol in 1 liter water.

[0047] When the carbon electrode produced by the following method is immersed in 1 mol of saline solution and allowed to stand for about 30 seconds, generation of fine bubbles from the entire surface of the carbon electrode, particularly from the side surface, is gradually recognized. Large amounts of hydrocarbons were confirmed when exudates from carbon sheets into solution by means of the chromatography. Therefore, when a section of the above-mentioned expanded carbon sheet was cut out and analyzed by using a method of detecting protons which are desorbed by irradiating pulsed electrons on the surface of a solid (electron excitation and desorption, TOF-ESD) at the Keihanna Laboratory Building TF Engineering Laboratory, ethylidyne (CH.sub.3C) having a molecular weight of 27 and ethylene (C.sub.2H.sub.4) having a molecular weight of 28 were detected in addition to hydrogen, oxygen, and carbon monoxide. When this ethylidyne is released into water, it is supposed that water molecules are separated into hydrogen ions and hydroxide ions, and hydrogen ions are reduced to generate hydrogen gas. In addition, it is supposed that it forms an ethylidyne metal complex when it is combined with a metal ion, which have a function as a water decomposition catalyst. The metal is not only selected from the group consisting a typical metal such as Al, Zn or Fe, but also a transition metal such as Cu.

[0048] Next, a copper plate (1 mm thickness, 5×15 cm) and a carbon electrode of the present invention are bonded together using a ring rubber or the like, or are placed opposite to each other and immersed in 1 mol of saline.

[0049] First, generation of hydrogen is observed from the carbon electrode, and thereafter, generation of hydrogen is also observed from the copper plate (FIG. 2A), and generation of hydrogen gas from the copper plate is observed even when the carbon electrode is desorbed from the saline solution. When the aluminum plate is immersed in this solution, hydrogen gas is also generated from the aluminum plate (2B in FIG.). It is presumed that the generation of hydrogen from the copper plate and the generation of hydrogen from the aluminum plate are the water decomposition effect of the ethylidyne copper complex formed between the copper plate and the aluminum plate. More specifically, if water is decomposed, as shown in FIG. 1. Hydrogen-evolving reaction is shown as

4H.sup.++2e.sup.−.fwdarw.2H.sub.2,

[0050] This phenomenon is somewhat complicated, but it is as follows. In other words, a pair of the carbon electrode and the metal electrode are put into the electrolytic solution.

[0051] Between the electrode materials subjected to the chemical reaction, there is the release of metal ions from the metal electrode, while there is the release of ethylidyne from the carbon electrode in the electrolytic solution. Therefore, on the metal side, the composition of the ethylidyne metal complex can be made by the adhesion of ethylidyne to the metal electrode. On the other hand, on the carbon material side, due to a difference in contact potential between a portion of carbon layer coated with metal ions and another carbon layer serving as a counter electrode a micro-cell can be made and an electric power effect is generated, whereby hydrogen is generated by electrolysis, and a capacitor portion has an electric storage action, which is cooperate with the micro-cell formed as shown in FIG. 8. Focusing on this carbon electrode portion, it is considered that the multilayer structure having a locally sub-nanometer space is formed, and the micro-cell structure in the nano-space in the surface layer portion is made and disappeared one after another, while the same cell action also occurs in the internal multilayer structure as described above, resulting in increasing generation of the electrolyzed hydrogen atom and the hydrogen molecule. Accordingly, it is considered that such a mechanism of electric power generation and a mechanism of hydrogen generation are understood as a phenomenon between the metal and the carbon. It is presumed that the ethylidyne or a metal complex thereof formed between the metal layer and the carbon layer can promote the above-mentioned electric power generation mechanism and the hydrogen generation mechanism by cooperation of the micro-cell and the micro-capacitor.

[0052] Reaction with Various Metals

[0053] When the carbon electrode of the present invention is immersed together with a copper plate in 1 molar saline solution, the carbon electrode exhibits a water decomposition action, and reacts violently with water to generate a large amount of hydrogen gas including vapor, and until the copper plate is decomposed into briquettes, the reaction proceeds. In addition, even if a zinc plate was used instead of the copper plate, the entire zinc plate became Zinc Oxide, and the water decomposition reaction became slow, but the reaction continues. In the case of aluminum plates, it was found to exhibit durability in saline and long-time hydrogen production capacity compared to copper and zinc. In particular, translucent crystals are formed around the carbon electrodes in the cell structure of the aluminum plate/1MNaCl+H.sub.2O.sub.2/the carbon electrodes. This crystal has a high oxygen content ratio and high conductivity, and forms a semi-solid electrolyte because aluminum hydroxide or sodium aluminate would contain ethylidyne. If the crystal electrolyte is interposed between aluminum/copper, zinc/copper, aluminum/carbon electrode, and carbon electrode/carbon electrode, the cell combination thereof can constitute a micro-cell and produce an electric power.

[0054] Preparation of Carbon Electrodes Containing Ethylidyne

[0055] In the method for producing a carbon electrode of the present invention, it is preferable that the electrode should be used as one or both of electrodes in an electrolyte solution. A water electrolysis reaction, or a electric power generation is necessary to improve the property of carbon electrode because such a process can make the carbon electrode to occlude hydrogen during electrolysis.

[0056] The step of separating and swelling the graphite layers is for separating the carbon electrode layers to have a specific gravity of 0.1 to 0.5 g/cm3. When the specific gravity is smaller than 0.1, the shape retention after swelling is poor, and when it is larger than 0.5, the interlayer separation after swelling is insufficient.

[0057] Concentrated nitric acid may be used as the oxidizing agent for the carbon electrode. This is because the catalytic function may be improved by pickling effect or oxidation action. In addition, the carbon electrode of the present invention can continue the catalytic function for a long period of time by mixing the radium ore powder having gamma ray radioactivity.

[0058] (Microscopic Photograph of Electrode)

[0059] FIGS. 10 (a) and (b) are SEM photographs at 10,000 times of a carbon electrode which has been swelled and oxidized after swelling. The oxidative graphite structure has a porous structure, the inside of which is cut into a triangular shape, and each layer exhibits translucency. FIGS. 10 (c) and (d) refer to the white-looking portion of the truncated tip, and it seems that Na+ is attached, and when the irradiation energy is concentrated, it shows a state of partial decomposition. As a result, flakes of graphite or graphene appear to accumulate. From the carbon-oxygen atom ratio shown in FIG. 11 between each layer, a structure in which an oxygen atom is bonded to each carbon atom (carbon-oxygen atom ratio is approximately 1 to 1) is shown. As a function of the structure, it is suggested that a new “carbon-oxygen” structure may be formed from the catalytic function for the redox reaction between peroxide and oxide in the positive electrode.

[0060] The microscopic Raman spectra of the carbon electrode A, the carbon electrode B and the carbon electrode C were measured by using a near-field optical microscope (NFS-230HKG) manufactured by Japan Spectroscopy Co., Ltd., wherein pumping wavelength: 532 nm, laser intensity: about 6.4 mW, slit width: diameter 100 μm, aperture: diameter 4000 μm, objective lens: ×20 (analytical diameter about 4 μm), exposure time×integrated number: 10 sec×2 times and the micro-Raman spectra of FIGS. 12A, B, C were obtained. Samples B and C were measured under the condition of peeling off the solid top from the sample. A change in the D-band of the sample from samples A to C are shown and the spectral peaks of Raman shift are moved from 1349.99 to 1356.11 cm.sup.−1.

EXAMPLES

[0061] As shown in FIG. 1A, carbon electrodes 20 of 15 mm thick and 100 square cm were prepared by a process wherein a carbon plate is immersed in an aqueous solution containing 1-1.5 molar NaCl salt and 0.5-1.0 molar dextrose for 1 day and night, and subjected to a swelling treatment by a flame-irradiation on both sides and, tightened with rubber bands.

[0062] The carbon electrode 20 together with a 3 mm-thick and 100 square-centimeter aluminum plate 10 are set in a bath containing 30° C. electrolytic solution 30 comprising 1-liter water, 15-20% by volume of 50% caustic soda solution and 0.5 molar of sodium chloride.

[0063] As hydrogen gas was evolved, heat was generated, reaching to 90° C. within 5 minutes, and the electrolytic solution reached to boiling point 106° C. immediately. The boiling was continued. Therefore, a steam together with hydrogen gas was evaporated at the open port of the electrolyte bath, so that the amount of electrolytic water was reduced quickly and violently. FIG. 1B is a photograph showing a state when the electrolytic water is boiled. Thus, it can be understood that the hydrogen gas supply system of the present invention can easily provide a large amount of hydrogen gas. In this case, a large amount of water vapor together with the hydrogen gas can collect only the hydrogen gas by collecting them in water or by cooling them.

INDUSTRIAL APPLICABILITY

[0064] According to the present invention, the hydrogen supply system comprises the carbon electrode and the metal electrode which are opposed to or in contact with each other without any external circuit. Thus, an electrolytic water such as sea water can be decomposed and hydrogen gas can be easily generated and supplied, so that it can be greatly utilized in the future hydrogen society.

DESCRIPTION OF SYMBOLS

[0065] 10; Copper plate, [0066] 20; Carbon electrode, [0067] 30; 1 molar saline electrolyte