JP2015063424A - Carbon-based material, electrode catalyst, electrode, electrochemical device, fuel cell and method for producing carbon-based material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon-based material which has high catalytic activity and can be easily produced and easily used as an electrode catalyst without requiring a binder.SOLUTION: There is provided a carbon-based material 1 which has a sheet-like shape, comprises a sheet material 2 made of amorphous carbon and further comprises an active layer 3 containing at least one kind of non-metallic atom selected from a nitrogen atom, a boron atom, a sulfur atom and a phosphorus atom and a metal atom.

Description

  The present invention relates to a carbon-based material suitable as a catalyst, an electrode catalyst including the carbon-based material, an electrode including the carbon-based material, an electrochemical device and a fuel cell including the electrode, and a method for producing the carbon-based material.

The oxygen reduction reaction shown below is a cathode reaction in an H ₂ / O ₂ fuel cell, salt electrolysis, etc., and is important in an energy conversion electrochemical device or the like.

O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O
The following oxygen generation reaction, which is the reverse reaction of this oxygen reduction reaction, is important as an anode reaction in water electrolysis and the like.

2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻
When oxygen reduction reaction or oxygen generation reaction proceeds in various devices, usually noble metals such as platinum, ruthenium oxide and iridium oxide are widely used as catalysts.

  For example, in Patent Document 1, when obtaining a gas diffusion electrode in a polymer electrolyte fuel cell, metal particles selected from the group consisting of a platinum group metal and a platinum group alloy are used as a catalyst, and this is used as a carrier such as carbon black powder. It is disclosed that a metal-supported catalyst is formed by supporting it, and the metal-supported catalyst is fixed to a gas diffusion layer made of carbon cloth or the like with a fluorine-containing ion exchange resin.

JP 2002-184414 A

  However, since noble metals are rare and expensive, and the price is unstable, using noble metals as a catalyst is necessary from the viewpoints of resource saving, securing availability, and cost reduction. ,There's a problem.

  Further, if the catalyst is in the form of particles, it takes time to fix the catalyst to the gas diffusion layer or the like as described above. In addition, in order to fix the catalyst to a member such as a gas diffusion layer, a binder such as a fluorine-containing ion exchange resin is required as described above. However, if the gas diffusion electrode is used for a long period of time, oxygen radicals generated by the electrode reaction The binder gradually deteriorates depending on the seeds. This causes the deterioration of the gas diffusion electrode over time.

  The present invention has been made in view of the above-mentioned reasons, and its object is to have high catalytic activity, can be easily manufactured, and can be easily used as an electrode catalyst without using a binder. Or a carbon-based material that can suppress deterioration in performance of the electrode over time even when another catalyst is fixed using a binder, an electrode catalyst including the carbon-based material, an electrode including the carbon-based material, It is an object of the present invention to provide an electrochemical device and a fuel cell including the electrode, and a method for producing the carbon-based material.

The carbonaceous material according to the first aspect is
Having a sheet-like shape,
Amorphous carbon sheet material,
And an active layer containing a nonmetallic atom containing one or more atoms selected from a nitrogen atom, a boron atom, a sulfur atom and a phosphorus atom, and a metal atom.

  In the carbon-based material according to the second aspect, in the first aspect, the sheet material is a woven or non-woven fabric made of amorphous carbon.

  The carbonaceous material according to the third aspect is porous in the first or second aspect.

  In the carbon-based material according to the fourth aspect, in any one of the first to third aspects, the surface layer of the sheet material is doped with the nonmetallic atom and the metal atom, and the active layer is formed on the surface layer. Is formed.

  The carbon-based material according to the fifth aspect is the carbon material according to any one of the first to fourth aspects, wherein the ratio of the metal atom to the carbon atom evaluated by XPS measurement is less than 0.01 and the non-carbon atom The ratio of metal atoms is less than 0.05.

  In the carbon-based material according to the sixth aspect, in the fourth or fifth aspect, the thickness of the active layer is 1 nm or less.

  In the carbon-based material according to the seventh aspect, in any one of the fourth to sixth aspects, the (002) plane peak in the diffraction intensity curve obtained by X-ray diffraction measurement using CuKα rays The ratio of the intensity of the maximum peak derived from the inert metal compound and the metal crystal to the intensity of 0.1 is 0.1 or less.

  In the carbon-based material according to the eighth aspect, in any one of the first to third aspects, the active layer contains a carbon compound having the nonmetal atom and the metal atom.

  In the carbon-based material according to the ninth aspect, in the seventh aspect, the carbon compound is a polymer having the organometallic complex having the nonmetallic atom and the metal atom, and the nonmetallic atom and the metal atom. At least one of the complexes is contained.

  In the carbon-based material according to the tenth aspect, in the eighth or ninth aspect, the active layer is formed by firing the carbon compound.

  In the carbon-based material according to an eleventh aspect, in any one of the first to tenth aspects, the non-metal atom includes a nitrogen atom, and the metal atom includes at least one of an iron atom and a cobalt atom. .

  The electrode catalyst according to the twelfth aspect includes the carbon-based material according to any one of the first to tenth aspects.

  An electrode according to a thirteenth aspect includes the carbon-based material according to any one of the first to eleventh aspects.

  The electrode according to the fourteenth aspect is configured as a gas diffusion electrode in the thirteenth aspect.

  An electrode according to a fifteenth aspect includes a water-repellent layer overlapping the carbonaceous material in the thirteenth or fourteenth aspect.

  In the electrode according to the sixteenth aspect, in the fifteenth aspect, the water repellent layer is porous.

  An electrochemical device according to a seventeenth aspect includes the electrode according to any one of the thirteenth to sixteenth aspects.

  A fuel cell according to an eighteenth aspect includes the electrode according to any one of the thirteenth to sixteenth aspects.

The method for producing a carbon-based material according to the nineteenth aspect includes
A nonmetallic compound having a nonmetallic atom containing one or more atoms selected from the group consisting of a nitrogen atom, a boron atom, a sulfur atom, and a phosphorus atom, and a metallic compound are attached to an amorphous carbon sheet material. A process of
Heating the nonmetallic compound, the metallic compound, and the sheet material at a temperature in the range of 800 ° C. to 1000 ° C. for a time in the range of 45 seconds to less than 600 seconds.

  In the method for producing a carbon-based material according to the twentieth aspect, in the nineteenth aspect, the sheet material is an amorphous carbon woven fabric or non-woven fabric.

In the carbon-based material manufacturing method according to the twenty-first aspect, in the nineteenth or twentieth aspect, the sheet material is porous. The carbon-based material according to the twenty-second aspect, any one of the nineteenth to twenty-first aspects. Manufactured by the method according to the embodiment.

  According to the present invention, since the catalytic activity of the carbon-based material can be improved, and further, an amorphous carbon sheet material can be used as a carbon source material for obtaining the carbon-based material. The material can be easily obtained, and the carbon-based material is in a sheet form, so that it can be easily applied as an electrode catalyst without using a binder, or a further catalyst can be added using a binder. Even if it is fixed, it is possible to suppress deterioration in performance of the electrode over time.

It is the schematic which shows the example of the electrode comprised only with the carbonaceous material and this carbonaceous material in one Embodiment of this invention. It is the schematic which shows the example of the electrode provided with the carbonaceous material and water repellent layer in one Embodiment of this invention. It is a graph which shows the voltammogram in the oxygen reduction area | region in 1M tris hydrochloride aqueous solution obtained by the voltammetry about the carbonaceous material obtained by Example 1. FIG. It is a graph which shows the voltammogram in the oxygen reduction area | region in 1M tris hydrochloride aqueous solution obtained by the voltammetry about the carbonaceous material obtained by Example 2. FIG. It is a graph which shows the voltammogram in the oxygen reduction area | region in 1M tris hydrochloride aqueous solution obtained by the voltammetry about the gas diffusion electrode provided with the carbonaceous material obtained by Example 1. FIG.

  The carbon-based material 1 according to this embodiment includes a sheet material 2 made of amorphous carbon and an active layer 3. The active layer 3 includes a nonmetallic atom and a metallic atom containing one or more atoms selected from a nitrogen atom, a boron atom, a sulfur atom, and a phosphorus atom.

  For this reason, in this embodiment, the carbonaceous material 1 has a high catalytic activity. Furthermore, since the easily available amorphous carbon sheet material 2 can be used as a carbon source material for obtaining the carbon-based material 1, the carbon-based material 1 can be easily obtained. Therefore, the carbon-based material 1 having high catalytic activity can be easily obtained. Further, since the carbon-based material 1 is in the form of a sheet, by using the carbon-based material 1 as a member constituting the electrode 6, it can be easily used as an electrode catalyst without requiring a binder.

  In the present specification, the term amorphous carbon is used in a general sense. That is, amorphous carbon means carbon that does not have a clear crystal structure. In particular, graphite (for example, PGS graphite sheet, 17 μm thickness, manufactured by Panasonic Corporation) having a peak intensity on the (002) plane in a diffraction intensity curve obtained by X-ray diffraction measurement of amorphous carbon using CuKα rays. It is preferable that the value of the ratio to the peak intensity of the (002) plane in the diffraction intensity curve obtained by X-ray diffraction measurement using CuKα rays is in the range of 0.05 to 0.5.

  The sheet material 2 is preferably an amorphous carbon woven or non-woven fabric. Moreover, it is also preferable that the carbonaceous material 1 is porous. In these cases, the carbonaceous material 1 can constitute an electrode catalyst at the same time as constituting the gas diffusion layer in the gas diffusion electrode.

  Non-metal atoms and metal atoms may be doped in the surface layer of the sheet material 2. In this case, the active layer 3 is formed on the surface layer of the sheet material 2. In this case, the conductivity of the carbon-based material 1 is not easily inhibited by the active layer 3. For this reason, especially when the carbonaceous material 1 is applied to an electrode catalyst, the catalytic activity is further improved.

  In the present embodiment, “non-metal atoms are doped” in the sheet material 2 means that the atoms constituting the sheet material 2 and the non-metal atoms are chemically bonded. In particular, it is preferable that nonmetallic atoms are incorporated in the carbon skeleton in the sheet material 2. More specifically, for example, it is preferable that one or more carbons in a carbon skeleton formed by sequentially bonding sp2 carbons are substituted with dopant atoms.

  Whether the sheet material 2 is doped with nonmetallic atoms can be confirmed, for example, by performing Raman spectroscopic measurement. Specifically, it can be confirmed that the sheet material 2 is doped with nonmetallic atoms, for example, by the following method. First, in the Raman spectrum obtained by Raman spectroscopic measurement for the carbon-based material 1, the peak of the G band derived from the bond due to the carbon sp2 orbital, and the peak of the D band derived from the bond defect due to the carbon sp2 orbital Confirm. The ratio (Id / Ig) between the intensity (Id) of the peak of the D band and the intensity (Ig) of the peak of the G band is increased by doping the sheet material 2 with a different element. When the intensity ratio (Id / Ig) is large compared to the case of the undoped sheet material 2, it can be confirmed that the different element is doped.

  It can be confirmed by X-ray photoelectron analysis that the sheet material 2 is doped with nonmetallic atoms. Specifically, for example, in the binding energy spectrum obtained by the X-ray photoelectron analysis method for the carbon-based material 1, the peak position derived from the nonmetallic atom doped in the sheet material 2 (for example, 1s orbital electron of nitrogen atom) It can be confirmed that the sheet material 2 is doped with non-metallic atoms based on the peak position derived from the above. For example, when the nonmetallic atom is a nitrogen atom, if the peak derived from the 1s orbital electron of the nitrogen atom in the binding energy spectrum is located near 399.9 eV, the nitrogen atom incorporated into the carbon skeleton Can be confirmed.

  In the present embodiment, the metal material is “doped” in the sheet material 2 means that the atoms constituting the sheet material 2 and the metal atom are chemically bonded. In particular, it is preferable that the metal atom is coordinated with a nonmetallic atom doped in the sheet material 2. In this case, the metal atoms doped in the sheet material 2 may not be directly bonded to the carbon atoms in the sheet material 2. In the radial distribution function obtained by Fourier transforming the K-edge broad X-ray absorption fine structure (EXAFS) of the metal atom for the carbon-based material 1, a peak is found near the coordination bond distance between the metal atom and the nonmetal atom. If it appears, the presence of a coordinate bond between a nonmetallic atom and a metal atom can be confirmed. Further, in the X-ray absorption spectrum (XAS) obtained for the carbonaceous material 1, the position of the absorption peak derived from the excitation of the non-metallic atom to the unoccupied orbital electron (for example, 1s orbital electron in the case of a nitrogen atom) And each of the absorption peak positions derived from the excitation of the inner electrons of the metal atoms (for example, 2p orbital electrons in the case of iron atoms) to the unoccupied orbital shifts from the peak position when there is no coordination bond. If the shift directions of these peak positions are different from each other, the presence of a coordinate bond between a nonmetal atom and a metal atom can be confirmed. This is because when a nonmetallic atom and a metal atom are coordinated, the electron density of one atom is high and the electron density of the other atom is low. That is, in XAS, the peak of absorption energy derived from an atom having a higher electron density among non-metallic atoms and metal atoms is shifted to the lower energy side, and the peak of absorption energy derived from an atom having a lower electron density is higher. This is because it shifts to the energy side.

  When the carbon-based material 1 is evaluated by XPS measurement, the ratio of metal atoms to carbon atoms may be less than 0.01, and the ratio of nonmetal atoms to carbon atoms may be less than 0.05. Thus, even if the doping amount of metal atoms is small, the carbon-based material 1 has a high catalytic activity.

The XPS measurement is performed under a vacuum condition of 3 × 10 ⁻⁸ Pa using an Al characteristic X-ray as a light source. When the XPS measurement of the carbonaceous material 1 is performed, the elemental composition within a certain region in the surface layer of the carbonaceous material 1 can be confirmed. For this reason, the doping amount of the metal atom in a fixed region is measured by XPS measurement. In addition, when “the ratio of the metal atom to the carbon atom evaluated by XPS measurement is less than 0.01”, the measurement is performed under the condition that the ratio of the metal atom to the carbon atom is 0.01 or more. This includes cases where the presence of metal atoms cannot be detected due to accuracy limitations. In addition, when “the ratio of the nonmetallic atom to the carbon atom evaluated by XPS measurement is less than 0.05”, it is possible to measure a nonmetallic atom having a ratio of 0.05 or more to the carbon atom. This includes the case where the presence of nonmetallic atoms cannot be detected due to the limit of measurement accuracy.

  In the XPS measurement of the carbonaceous material 1, the amount of mixed substances existing independently of the carbonaceous material 1 is sufficiently reduced by washing the carbonaceous material 1 with an acidic aqueous solution in advance. In the acid cleaning, for example, the carbon-based material 1 is put in 2M sulfuric acid and stirred at 80 ° C. for 3 hours.

  The thickness of the active layer 3 is preferably 1 nm or less. As described above, since the thickness of the active layer 3 is thin, the conductivity of the carbon-based material 1 is further hardly inhibited by the active layer 3. For this reason, especially when the carbonaceous material 1 is applied to an electrode catalyst, the catalytic activity is further improved.

  In addition, the case where “the thickness of the active layer 3 is 1 nm or less” includes the case where the presence of the active layer 3 cannot be confirmed due to the limit of measurement accuracy under the condition that the active layer 3 exceeding 1 nm can be measured. .

  In the diffraction intensity curve obtained by X-ray diffraction measurement of the carbon-based material 1 using CuKα ray, the maximum peak intensity derived from the inert metal compound and the metal crystal with respect to the peak intensity of the (002) plane The ratio is preferably 0.1 or less. In this case, the catalytic activity of the carbonaceous material 1 is further improved. This is presumably because the catalytic activity of the carbon-based material 1 is hardly inhibited by the metal compound and the metal crystal because the contents of the inert metal compound and the metal crystal are small.

  In addition, an inert metal compound is a compound in which the metal atom which is not doped by the sheet | seat material 2 in the carbonaceous material 1 becomes a component, for example, a metal carbide, a metal nitride, and a metal sulfide. is there. The metal crystal is a crystal composed of metal atoms that are not doped in the sheet material 2.

  In evaluating the intensity of the peak of the diffraction intensity curve, the baseline of the diffraction intensity curve is determined by the Shirley method. Based on this baseline, the peak intensity of the diffraction intensity curve is determined.

  In addition, in the X-ray diffraction measurement of the carbon-based material 1, the mixing amount of substances existing independently of the carbon-based material 1 is sufficiently reduced by washing the carbon-based material 1 with an acidic aqueous solution in advance. Keep it. In the acid cleaning, for example, the carbon-based material 1 is put in 2M sulfuric acid and stirred at 80 ° C. for 3 hours.

  The active layer 3 may contain a carbon compound having a nonmetal atom and a metal atom. In this case, the conductivity of the carbon-based material 1 is not easily inhibited by the active layer 3. For this reason, especially when the carbonaceous material 1 is applied to an electrode catalyst, the catalytic activity is further improved. The carbon compound is at least one of, for example, an organometallic complex having a nonmetallic atom and a metal atom and a polymer complex having a nonmetallic atom and a metal atom. The active layer 3 may be formed by firing a carbon compound.

  It is preferable that the nonmetallic atom in the active layer 3 contains a nitrogen atom, and a metal atom contains at least one of an iron atom and a cobalt atom. A nonmetallic atom may be only a nitrogen atom. Further, the metal atom may be at least one of an iron atom and a cobalt atom.

  In this case, the carbonaceous material 1 has a particularly high catalytic activity. For this reason, when the carbonaceous material 1 is applied to an electrode catalyst, in particular, an oxygen reduction electrode catalyst or an oxygen generation catalyst, very excellent performance is exhibited.

  Hereinafter, the more specific form of the carbonaceous material 1 which concerns on this embodiment is demonstrated.

  First, the 1st form of the carbonaceous material 1 which concerns on this embodiment is demonstrated. The carbon-based material 1 according to this embodiment is formed by doping a non-metallic atom and a metal atom on the surface layer of an amorphous carbon sheet material 2. Therefore, the active layer 3 is formed on the surface layer of the sheet material 2. In other words, the carbon-based material 1 according to this embodiment includes the core layer 4 substantially made of amorphous carbon, and the active layer 3 that covers the core layer 4 and contains nonmetallic atoms and metal atoms. This is because, when the carbon material 1 is manufactured, when the sheet material 2 is doped with a metal atom and a nonmetal atom, the nonmetal atom and the metal atom easily penetrate into the sheet material 2. This is because the surface layer of the sheet material 2 is mainly doped.

  The carbonaceous material 1 is preferably porous. In this case, the carbonaceous material 1 is suitable as a member constituting the electrode 6, and particularly suitable as a gas diffusion layer in the gas diffusion electrode.

  The sheet material 2 made of amorphous carbon is, for example, a woven fabric or a nonwoven fabric made of amorphous carbon. In this case, the carbonaceous material 1 becomes porous. In this case, the active layer 3 is formed on the surface layer of the fibers 5 (amorphous carbon fibers) constituting the sheet material 2. In other words, the fiber 5 constituting the sheet material 2 includes a core layer 4 substantially made of amorphous carbon and an active layer 3 that covers the core layer 4 and contains nonmetallic atoms and metal atoms.

  The dimension in particular of carbonaceous material 1 is not restrict | limited, For example, this carbonaceous material 1 may have a minute dimension.

  The metal atoms doped in the sheet material 2 are not particularly limited, but titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni ), Copper (Cu), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), hafnium (Hf), tantalum (Ta) ), Tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au). In this case, the carbonaceous material 1 exhibits excellent performance, particularly as a catalyst for promoting the oxygen reduction reaction. The amount of metal atoms doped in the sheet material 2 may be set as appropriate so that the carbon-based material 1 exhibits excellent catalytic performance.

  As described above, the nonmetallic atom doped in the sheet material 2 contains one or more atoms selected from a nitrogen atom, a boron atom, a sulfur atom, and a phosphorus atom. The amount of nonmetallic atoms doped in the sheet material 2 may be set as appropriate so that the carbonaceous material 1 exhibits excellent catalytic performance.

  A combination of metal atoms and nonmetal atoms doped in the sheet material 2 is appropriately selected. In particular, when the carbonaceous material 1 is applied to an oxygen reduction electrode catalyst, it is preferable that the nonmetallic atom contains a nitrogen atom and the metallic atom contains an iron atom. In this case, the carbonaceous material 1 can exhibit particularly excellent catalytic activity. A nonmetallic atom may be only a nitrogen atom. Further, the metal atom may be only an iron atom.

  Moreover, when the carbonaceous material 1 is applied to an oxygen generation electrode, it is preferable that a nonmetallic atom contains a nitrogen atom and a metal atom contains at least one of a cobalt atom and a manganese atom. In this case, the carbonaceous material 1 can exhibit particularly excellent catalytic activity. A nonmetallic atom may be only a nitrogen atom. Further, the metal atom may be only a cobalt atom, only a manganese atom, or only a cobalt atom and a manganese atom.

  According to the cyclic voltammetry measurement result (voltammogram) of the carbon-based material 1 according to this embodiment, a peak derived from the oxidation-reduction reaction of metal atoms (ions) doped in the sheet material 2 appears in the voltammogram. In other words, it can be confirmed that the sheet material 2 is doped with metal atoms based on the presence of a peak derived from oxidation and reduction of the metal atoms. In addition, the average value (oxidation-reduction potential) of the potential at the peak position during the oxidation reaction and the potential at the peak position during the reduction reaction in this voltammogram is shifted according to the type of the nonmetallic atom doped in the sheet material 2. To do. In other words, it can be confirmed that the sheet material 2 is doped with nonmetallic atoms based on the value of the oxidation-reduction potential or the shift amount. In addition, since it is considered that an electrochemical reaction on the carbon-based material 1 occurs on the surface of the carbon-based material 1, it can be evaluated that metal atoms and non-metal atoms exist in the surface layer of the sheet material 2.

  It is preferable that the carbonaceous material 1 which concerns on this form does not contain the particle | grains with a diameter of 1 nm or more containing at least one among an inert metal compound and a metal crystal. In particular, the carbonaceous material 1 preferably does not contain particles containing at least one of an inert metal compound and a metal crystal regardless of the particle size.

  Note that the presence and particle size of particles containing at least one of an inert metal compound and a metal crystal are confirmed by observing the carbon-based material 1 with a transmission electron microscope. “Does not contain particles having a diameter of 1 nm or more including at least one of an inert metal compound and a metal crystal” means that any position of the carbon-based material 1 is observed when the carbon-based material 1 is observed with a transmission electron microscope. Even so, it means that the presence of particles having a diameter of 1 nm or more containing at least one of an inert metal compound and a metal crystal is not observed from an image obtained by a transmission electron microscope. In addition, the diameter of particle | grains is a perfect circle | round | yen conversion diameter obtained by image-processing the image of the particle | grains obtained with a transmission electron microscope. As the transmission electron microscope, for example, model number H-9000UHR manufactured by Hitachi High-Technologies Corporation can be used.

  In observing the carbon-based material 1 with a transmission electron microscope, the carbon-based material 1 is washed in advance with an acidic aqueous solution, and the amount of substances existing independently of the carbon-based material 1 is sufficiently increased. Reduce it. In the acid cleaning, for example, the carbon-based material 1 is put in 2M sulfuric acid and stirred at 80 ° C. for 3 hours.

  As described above, when the carbonaceous material 1 does not contain particles having a diameter of 1 nm or more including at least one of an inert metal compound and a metal crystal, the catalytic activity of the carbonaceous material 1 is further increased. This is because there are no particles containing at least one of an inert metal compound and a metal crystal, or since the particles are very small, the catalytic activity of the carbon-based material 1 is hardly inhibited by the metal compound and the metal crystal. It is thought that it is from. In addition, it is thought that the particle | grains containing at least one among an inert metal compound and a metal crystal generate | occur | produce when an inert metal compound and a metal crystal generate | occur | produce in the manufacture process of the carbonaceous material 1 without a metal atom being doped. .

  In addition, particles containing at least one of an inert metal compound and a metal crystal are aggregated as they are after the metal atoms once doped in the carbon-based material 1 are released or aggregated as they are combined with carbon atoms or the like. It is thought that this also occurs. For this reason, there is no particle containing at least one of an inert metal compound and a metal crystal, or the fact that this particle is very small means that the elimination of metal atoms from the carbon-based material 1 is suppressed, and the carbon-based material This is considered to mean that a sufficient amount of metal atoms are distributed on the surface layer of the material 1. This is also considered to be a cause of the high catalytic activity of the carbonaceous material 1 according to this embodiment.

  Moreover, the ratio of the metal atom with respect to the carbon atom evaluated by measuring XPS (X-ray photoelectron spectroscopy) of the carbonaceous material 1 according to this embodiment is less than 0.01, and the ratio of the nonmetallic atom with respect to the carbon atom. Is preferably less than 0.05. In this case, since the amount of metal atoms and nonmetal atoms in a certain region in the surface layer of the carbonaceous material 1 is small, it can be evaluated that the doping amount of the metal atoms and nonmetal atoms in the carbonaceous material 1 is small. In this embodiment, the carbon-based material 1 having high catalytic activity can be obtained even when the doping amount of metal atoms is small.

  The ratio of metal atoms to carbon atoms is particularly preferably 0. The ratio of nonmetallic atoms to carbon is particularly preferably 0. In addition, the ratio of this metal atom and a nonmetallic atom is a value evaluated by XPS measurement to the last, and even if this value is 0, the quantity of the metal atom and nonmetallic atom in the surface layer of the carbonaceous material 1 actually Is not 0. The presence of metal atoms and non-metal atoms in the surface layer of the carbon-based material 1 is confirmed from the measurement result of the carbon-based material 1 by cyclic voltammetry.

  Moreover, it is preferable that the thickness of the active layer 3 in the carbonaceous material 1 which concerns on this form is 1 nm or less. In this case, since the thickness of the active layer 3 is thin, the conductivity of the carbon-based material 1 is not easily inhibited by the active layer 3. As described above, when “the thickness of the active layer 3 is 1 nm or less”, the presence of the active layer 3 cannot be confirmed due to the limit of measurement accuracy under the condition that the active layer 3 exceeding 1 nm can be measured. Therefore, a preferable lower limit of the thickness of the active layer 3 is not specified. Even if the presence of the active layer 3 cannot be confirmed, it cannot be said that there are no metal atoms and non-metal atoms in the surface layer of the carbon-based material 1. The presence of metal atoms and non-metal atoms in the surface layer of the carbon-based material 1 is confirmed from the measurement result by cyclic voltammetry of the carbon-based material 1 as described above.

  In addition, the carbon-based material 1 according to this embodiment is derived from an inert metal compound and a metal crystal with respect to the peak intensity on the (002) plane in a diffraction intensity curve obtained by X-ray diffraction measurement using CuKα rays. The maximum peak intensity ratio is preferably 0.1 or less. In this case, the ratio of the inert metal compound and the metal crystal in the carbonaceous material 1 is very low. For this reason, the catalytic activity of the carbonaceous material 1 is further improved. The ratio of the peak intensities is preferably as small as possible, and it is particularly preferable if the peak derived from the inert metal compound and the metal crystal is not observed in the diffraction intensity curve.

  In evaluating the intensity of the peak of the diffraction intensity curve, the baseline of the diffraction intensity curve is determined by the Shirley method. Based on this baseline, the peak intensity of the diffraction intensity curve is determined.

  In addition, when performing X-ray diffraction measurement of the carbonaceous material 1 which concerns on this form, only the carbonaceous material 1 becomes a measuring object, The substance mixed in the carbonaceous material 1, and the carbonaceous material 1 Substances existing independently of the carbonaceous material 1 such as substances adhering to the surface are excluded from the measurement target. For this reason, in the X-ray diffraction measurement of the carbon-based material 1, the carbon-based material 1 is washed with an acidic aqueous solution in advance so that the amount of substances existing independently of the carbon-based material 1 is sufficiently increased. It is necessary to reduce it. In the acid cleaning, for example, the carbon-based material 1 is put in 2M sulfuric acid and stirred at 80 ° C. for 3 hours.

  Further, graphite (for example, PGS graphite manufactured by Panasonic Corporation) having a peak intensity on the (002) plane in a diffraction intensity curve obtained by X-ray diffraction measurement of the carbon-based material 1 according to this embodiment using CuKα rays. The ratio of the (002) plane peak to the intensity in the diffraction intensity curve obtained by X-ray diffraction measurement of the sheet (17 μm thick) using CuKα rays is in the range of 0.05 to 0.5. Preferably there is.

  In the diffraction intensity curves for the carbonaceous material 1 and graphite, the peak on the (002) plane appears at a position where 2θ is around 26 °. θ represents an incident angle of X-rays to the sample at the time of X-ray diffraction measurement. Also, the baseline of the diffraction intensity curve is determined by the Shirley method, and the peak intensity of the diffraction intensity curve is determined based on this baseline.

  The carbonaceous material 1 according to the present embodiment exhibits excellent catalytic performance when used as an electrode catalyst as described above, and particularly an excellent catalyst when used as an oxygen reduction catalyst or as an oxygen generation catalyst. Demonstrate performance.

  Next, the manufacturing method of the carbonaceous material 1 which concerns on a 1st form is demonstrated.

  In this production method, a nonmetallic compound having a nonmetallic atom containing one or more atoms selected from a nitrogen atom, a boron atom, a sulfur atom, and a phosphorus atom, and a metal compound are converted into an amorphous carbon sheet material 2. And a step of heating the nonmetallic compound, the metal compound, and the sheet material 2 at a temperature in the range of 800 ° C. to 1000 ° C. for a time in the range of 45 seconds to less than 600 seconds.

  The sheet material 2 is, for example, an amorphous carbon woven fabric or non-woven fabric. Moreover, the sheet | seat material 2 is porous, for example.

  By this production method, the carbon-based material 1 having high catalytic activity is obtained. Furthermore, since the easily available amorphous carbon sheet material 2 is used as a carbon source material for obtaining the carbon-based material 1, the carbon-based material 1 can be easily obtained. Furthermore, since the sheet-like carbonaceous material 1 is obtained, by using this carbonaceous material 1 as a member constituting the electrode 6, it can be easily used as an electrode catalyst without requiring a binder.

  In this production method, the sheet material 2 made of a nonmetallic compound, a metal compound, and amorphous carbon is heated at a high temperature for a short time, so that metal atoms are not doped into the sheet material 2 in the process of heating them. It is considered that the generation of an active metal compound or metal crystal is suppressed, and the catalytic activity of the carbonaceous material 1 is therefore increased. That is, the inert metal compound and the metal crystal are not present in the carbon-based material 1 or the amounts thereof are reduced, so that the catalytic activity of the carbon-based material 1 is inhibited by the inert metal compound and the metal crystal. It is considered to be suppressed.

  Moreover, when the nonmetallic compound, the metallic compound, and the sheet material 2 made of amorphous carbon are heated at a high temperature for a short time, the metal atoms once doped in the carbonaceous material 1 are difficult to desorb. For this reason, it is considered that the metal atoms are eliminated and aggregated as they are, or the metal atoms are bonded to carbon atoms and the like to be aggregated. This is also considered to be a cause of the suppression of the formation of inert metal compounds and metal crystals. In addition, when the detachment of metal atoms from the carbon-based material 1 is suppressed as described above, a sufficient amount of metal atoms is distributed on the surface layer of the carbon-based material 1. This is also considered to be a cause of the high catalytic activity of the carbonaceous material 1.

  The manufacturing method of the carbonaceous material 1 which concerns on this form is demonstrated more concretely.

  In this manufacturing method, a sheet material 2 made of amorphous carbon is prepared. As described above, the sheet material 2 is preferably porous. Such a sheet material 2 is, for example, an amorphous carbon woven fabric or non-woven fabric. The dimension in particular of the sheet material 2 is not restrict | limited, For example, this sheet material 2 may have a minute dimension. Graphite (for example, PGS graphite sheet, 17 μm thickness, manufactured by Panasonic Corporation) having a peak intensity on the (002) plane in a diffraction intensity curve obtained by X-ray diffraction measurement of this sheet material 2 using CuKα rays. In the diffraction intensity curve obtained by X-ray diffraction measurement using CuKα rays, the value of the ratio to the peak intensity of the (002) plane is preferably in the range of 0.05 to 0.5.

  The metal compound can contain an appropriate compound having a metal atom that can be doped into the sheet material 2 made of amorphous carbon. For example, the metal compound is an inorganic metal salt such as a metal chloride salt, nitrate, sulfate, bromide salt, iodide salt, fluoride salt, etc .; an organic metal salt such as acetate; a hydrate of an inorganic metal salt; And one or more compounds selected from organic metal salt hydrates. For example, when the sheet material 2 is doped with iron atoms, the metal compound preferably contains iron (III) chloride. In addition, when the sheet material 2 is doped with cobalt atoms, the metal compound preferably contains cobalt chloride. In addition, when the sheet material 2 is doped with manganese atoms, the metal compound preferably contains manganese acetate.

  The amount of the metal compound used is appropriately set according to the amount of metal atoms doped into the sheet material 2. For example, the amount of the metal compound used is preferably determined so that the ratio of the metal atoms in the metal compound to the sheet material 2 is 5 to 30% by mass, and this ratio is in the range of 5 to 20% by mass. It is preferable to be determined as follows.

  As described above, the nonmetallic compound has a nonmetallic atom containing one or more atoms selected from a nitrogen atom, a boron atom, a sulfur atom, and a phosphorus atom. Nonmetallic compounds include, for example, pentaethylenehexamine, ethylenediamine, tetraethylenepentamine, triethylenetetramine, ethylenediamine, octylboronic acid, 1,2-bis (diethylphosphirietan), triphenyl phosphite and benzyl disulfide. One or more compounds selected from the group consisting of:

  In particular, it is preferable that the nonmetallic compound contains a compound that can react with a metal atom doped in the sheet material 2 to form a complex. In particular, one or more compounds selected from the group consisting of pentaethylenehexamine, ethylenediamine, tetraethylenepentamine, triethylenetetramine, and ethylenediamine as a compound that can form a complex by reacting a metal atom with a metal atom. It is preferable to contain. In this case, the catalytic activity of the carbonaceous material 1 is particularly high. The reason is assumed to be as follows. When a compound capable of forming a complex by reacting with a metal atom is used, the metal atom derived from the metal compound and the nonmetal compound are temporarily transferred in the process of doping the metal atom and the nonmetal atom into the sheet material 2. It is considered that the metal material and the non-metal atom are easily doped into the sheet material 2 after forming a complex. As a result, in the carbon-based material 1, it is considered that a metal atom and a nonmetal atom are coordinated. Here, it is considered that the catalytic activity of the carbonaceous material 1 is expressed at a position in the carbonaceous material 1 where the nonmetallic atom and the metal atom are close to each other. For this reason, it is considered that the catalytic activity of the carbon-based material 1 is further improved by using a nonmetallic compound that can react with a metal atom to form a complex. Here, it is considered that the catalytic activity of the carbonaceous material 1 is expressed at a position in the carbonaceous material 1 where the nonmetallic atom and the metal atom are close to each other. For this reason, it is considered that the catalytic activity of the carbon-based material 1 is further improved by using a nonmetallic compound that can react with a metal atom to form a complex.

  Note that, as described above, according to the measurement result of the carbon-based material 1 by cyclic voltammetry, the oxidation-reduction potential shifts according to the type of the nonmetallic atom doped in the carbon-based material 1. This redox potential shift is considered to be due to the change in the electronic state of the metal atom due to the coordinate bond between the metal atom and the nonmetal atom. In other words, when the oxidation-reduction potential of the carbon-based material 1 is shifted, it can be evaluated that the metal atom and non-metal atom doped in the carbon-based material 1 are coordinated.

  The molecular weight of the nonmetallic compound is preferably 800 or less. In this case, the nonmetallic atom derived from the nonmetallic compound is easily doped into the sheet material 2. This is because the nonmetallic compound has a small molecular weight, so that the nonmetallic compound is thermally decomposed in a short time to generate nonmetallic atoms, and thus the nonmetallic atoms are quickly doped into the sheet material 2. ,Conceivable.

  The amount of the nonmetallic compound used is appropriately set according to the amount of the nonmetallic atom doped into the sheet material 2. For example, the amount of the nonmetallic compound used is preferably determined so that the molar ratio of the metal atom in the metal compound to the nonmetallic atom in the nonmetallic compound is in the range of 1: 1 to 1: 2. Further, it is preferable that the molar ratio is determined to be in the range of 1: 1.5 to 1: 1.8.

  The metal compound and the nonmetal compound are doped into the sheet material 2 as follows, for example. First, a solution containing a metal compound and a nonmetal compound is prepared. This solution is dropped on the sheet material 2 placed on a hot plate at 80 ° C. and then heated. Thereby, a metallic compound and a nonmetallic compound adhere to the sheet material 2.

  Next, the metal compound, the nonmetal compound, and the sheet material 2 are heated. This heating is performed by an appropriate method. For example, the metallic compound, the nonmetallic compound, and the sheet material 2 can be heated in a reducing atmosphere or an inert gas atmosphere. Thereby, the metal material and the nonmetal atom are doped in the sheet material 2. The heating temperature during this heat treatment is in the range of 800 ° C. or more and 1000 ° C. or less, and the heating time is in the range of 45 seconds or more and less than 600 seconds. Since the heating time is short in this way, the carbon-based material 1 is efficiently produced, and the catalytic activity of the carbon-based material 1 is further increased.

  In this heat treatment, it is preferable that the temperature increase rate when the metal compound, the nonmetal compound, and the sheet material 2 are heated to the heating temperature is 50 ° C./s or more. As described above, when the metal compound, the nonmetal compound, and the sheet material 2 are rapidly heated, the catalytic activity of the carbon-based material 1 is further increased. This is considered to be because the amount of the inert metal compound and the metal crystal in the carbon-based material 1 is further reduced.

  The carbon-based material 1 may be further subjected to acid cleaning. In the acid cleaning, for example, the carbon-based material 1 is put in 2M sulfuric acid and stirred at 80 ° C. for 3 hours. When such acid cleaning is performed, the overvoltage in the case where the carbon-based material 1 is applied as a catalyst is not significantly changed as compared with the case where the acid cleaning is not performed, but the metal from the carbon-based material 1 is not changed. Elution of components is suppressed.

  By such a production method, the carbon-based material 1 having a significantly low content of inert metal compounds and metal crystals and high conductivity can be obtained.

  Next, the 2nd form of the carbonaceous material 1 which concerns on this embodiment is demonstrated. The carbonaceous material 1 which concerns on this form is provided with the active layer 3 containing the carbon compound which has a nonmetallic atom and a metal atom.

  The carbon compound contains at least one of, for example, an organometallic complex and a polymer complex having a nonmetallic atom and a metal atom. Specific examples of the organometallic complex include a cobalt porphyrin complex and an iron porphyrin complex. Specific examples of the polymer complex include Poly (bis-2,6-diaminopyridinesulfoxide) and cobalt polypyrrole.

  In producing the carbon-based material 1 according to this embodiment, for example, first, a coating agent containing a carbon compound is prepared, and this coating agent is applied to the sheet material 2 made of amorphous carbon. Thereby, the active layer 3 containing a carbon compound is formed on the sheet material 2. Moreover, after apply | coating a coating agent to the sheet | seat material 2, this coating agent may be heated and baked. In this case, the heating temperature is preferably in the range of 700 to 1000 ° C., and the heating time is preferably in the range of 1 to 3 hours. As a result, an active layer 3 made of a fired carbon compound is formed on the sheet material 2. Thereby, the sheet-like carbonaceous material 1 provided with the active layer 3 in the outermost layer is obtained.

  Since the carbonaceous material 1 according to the present embodiment has high catalytic activity and high conductivity, in particular, a catalyst used for advancing a chemical reaction on the electrode 6 by an electrochemical method (that is, Suitable as an electrode catalyst). Furthermore, it is suitable as a catalyst used for advancing the oxygen reduction reaction on the electrode 6 (ie, an oxygen reduction electrode catalyst), or a catalyst used for advancing the oxygen generation reaction on the electrode 6 (ie, Suitable as an oxygen generating electrode catalyst). Further, it is particularly suitable as a catalyst applied to a gas diffusion electrode used for reducing oxygen in the gas phase.

  The electrode catalyst including the carbon-based material 1 according to the present embodiment and the electrode 6 including the carbon-based material 1 according to the present embodiment will be described.

  The electrode catalyst according to this embodiment includes a carbon-based material 1. This electrode catalyst has excellent performance because the carbonaceous material 1 exhibits high catalytic activity. Moreover, this electrode catalyst can be easily applied to the electrode 6 without requiring a binder. This electrode catalyst is particularly suitable as an oxygen reduction electrode catalyst or an oxygen generation electrode catalyst.

  The electrode 6 according to this embodiment includes a carbon-based material 1. In this case, since the carbonaceous material 1 has excellent performance as an electrode catalyst, the electrode 6 also has excellent performance. Moreover, since the carbonaceous material 1 can be easily applied to the electrode 6 without requiring a binder, the electrode 6 can be easily obtained. This electrode 6 is particularly suitable as an oxygen reduction electrode or an oxygen generation electrode.

  The electrode 6 according to the present embodiment may be configured as a gas diffusion electrode. In particular, when the carbon-based material 1 is porous, the carbon-based material 1 can serve as both an electrode catalyst and a gas diffusion layer.

  The electrode 6 according to this embodiment may include a water repellent layer 7. In particular, when the electrode 6 is configured as a gas diffusion electrode, the electrode 6 preferably includes the water repellent layer 7. In this case, the water repellent layer 7 can prevent the electrolytic solution from passing through the electrode 6. Further, the water repellent layer 7 can improve the durability of the electrode 6.

  The water repellent layer 7 is preferably porous. In this case, the water-repellent layer 7 can prevent the electrolytic solution from passing through the electrode 6 and allow gas to pass through the electrode 6. For this reason, the electrode 6 has the outstanding performance especially as a gas diffusion electrode.

  The electrode 6 according to this embodiment will be described in more detail.

  When the electrode 6 is configured as a gas diffusion electrode, the electrode 6 includes a gas diffusion layer made of the carbon-based material 1. The electrode 6 may further include a support as necessary, and the carbon-based material 1 may be supported on the support. Further, the electrode 6 may be composed of only the carbon-based material 1. A catalyst is not necessarily fixed to the carbon-based material 1 separately from the carbon-based material 1.

  The support is a member that itself has rigidity and can give the electrode 6 a certain shape. The material of the support is not particularly limited as long as the electrode 6 has sufficient rigidity to maintain a certain shape. The support may be an insulator or a conductor. When the support is an insulator, the support may be, for example, glass, plastic, synthetic rubber, ceramics, water and water repellent treated paper and plant pieces (eg, including wood pieces), and animal pieces (eg, Made of one or more materials selected from bone fragments, shells and sponges). If the support is porous, the area of the surface of the support that can contact the carbon-based material 1 increases, so that the mass activity of the electrode 6 increases. The porous support is made of, for example, one or more materials selected from the group consisting of porous ceramics, porous plastics, and animal pieces. When the support is a conductor, the support is, for example, one or more selected from the group consisting of carbon-based materials (including carbon paper, carbon fibers, carbon rods), metals, and conductive polymers. Made from material. When the support is a conductor, for example, when the carrier carrying the carbon-based material 1 is disposed on the surface of the support, the support can also serve as a current collector.

  When the electrode 6 includes a support, the shape of the support usually reflects the shape of the electrode 6. The shape of the support is not particularly limited as long as it can fulfill the function of the electrode 6, and may be appropriately determined according to the shape of the fuel cell or the like. Examples of the shape of the support include (substantially) flat plate (including a thin layer), (substantially) columnar, (substantially) spherical, and combinations thereof.

  When the electrode 6 is comprised only from the carbonaceous material 1, the carbonaceous material 1 shown by FIG. 1, for example can comprise the electrode 6 (61). The carbon-based material 1 serves as an electrode catalyst and a gas diffusion layer, and the electrode 61 is configured as a gas diffusion electrode.

  In addition to the carbon-based material 1, the electrode 6 may further include a particulate electrode catalyst. In this case, the reaction activity of the electrochemical reaction on the electrode 6 is further improved. The particulate electrode catalyst is fixed to the carbon-based material 1 by, for example, a conductive binder. There is no restriction | limiting in particular in a particulate electrode catalyst.

  The electrode 6 may include a water repellent layer 7. In particular, when the electrode 6 configured as a gas diffusion electrode includes the water repellent layer 7, the water repellent layer 7 can inhibit the permeation of the electrolytic solution. Therefore, the water repellent layer 7 can satisfactorily separate the gas phase and the liquid phase in the electrochemical system including the electrode 6. The water repellent layer 7 is preferably located on the gas phase side with respect to the carbon-based material 1 constituting the gas diffusion layer.

  In FIG. 2, an example of the electrode 6 (62) provided with the water repellent layer 7 is shown. The electrode 62 includes the carbon-based material 1 and the water repellent layer 7 shown in FIG. In the electrode 62, the water-repellent layer 7 is provided outside the carbon-based material 1 and overlapped with the carbon-based material 1. When the water repellent layer 7 is formed outside the carbon-based material 1, the water-repellent layer 7 and the carbon-based material 1 may not be in contact with each other, but the distance between the water-repellent layer 7 and the carbon-based material 1. The closer is, the better. Further, the water repellent layer 7 may be formed inside the carbon-based material 1 when the carbon-based material 1 is porous. Further, the water repellent layer 7 may be formed both inside and outside the carbon-based material 1.

  The water repellent layer 7 is preferably porous. In this case, the water repellent layer 7 has both water repellency and high gas permeability. For this reason, the water repellent layer 7 can permit the movement of the gas from the gas phase toward the liquid phase while favorably separating the gas phase and the liquid phase in the electrochemical system including the electrode 62.

  The water repellent layer 7 is made of, for example, one or more materials selected from the group consisting of polytetrafluoroethylene (PTFE), dimethylpolysiloxane (PDMS), polyethylene (PE), and polypropylene (PP).

  An electrochemical device including the electrode 6 according to this embodiment will be described. The electrode 6 including the carbon-based material 1 can be applied to any of an anode and a cathode in various electrochemical devices. Specific examples of the electrochemical device include a fuel cell, a water electrolysis device, a carbon dioxide permeation device, a salt electrolysis device, a metal air battery (metal lithium air battery), and the like. For example, the electrode 6 can be applied to a cathode in a carbon dioxide permeation device, a salt electrolysis device, or the like.

  When the carbon-based material 1 serves as an oxygen reduction electrode catalyst, the electrode 6 including the carbon-based material 1 is applied to, for example, a cathode in a fuel cell, a cathode in a carbon dioxide permeation device, a cathode in a salt electrolysis device, and the like. Moreover, when the carbonaceous material 1 functions as an oxygen generating electrode catalyst, the electrode 6 including the carbonaceous material 1 is applied to, for example, an anode in a water electrolysis apparatus, an anode in a metal-air battery, and the like.

  A fuel cell including the electrode 6 according to this embodiment will be described. The fuel cells referred to in this specification include hydrogen fuel cells such as polymer electrolyte fuel cells (PEFCs) and phosphoric acid fuel cells (PAFCs), and microbial fuel cells (MFCs). : Microbial Fuel Cell).

A hydrogen fuel cell is a fuel cell that obtains electric energy from hydrogen and oxygen based on the reverse operation of water electrolysis, and is a PEFC, PAFC, alkaline fuel cell (AFC), molten carbonate fuel cell. (MCFC; Molten Carbonate Fuel Cell), solid oxide fuel cell (SOFC), and the like are known. The fuel cell according to the present embodiment is preferably PEFC or PAFC. PEFC is a proton conductive ion exchange membrane, and PAFC is a fuel cell using phosphoric acid (H ₃ PO ₄ ) impregnated in a matrix layer as an electrolyte material.

  The fuel cell including the electrode 6 according to the present embodiment can be suitably applied to a hydrogen fuel cell, an MFC, or the like. The fuel cell may have a known configuration in each fuel cell, except that the fuel cell includes a gas diffusion electrode including an electrode catalyst including the carbon-based material 1. For example, the fuel cell is “Fuel cell technology”, edited by the IEEJ Fuel Cell Power Generation Next Generation System Technology Research Special Committee, Ohm, H17, Watanabe, K., J. Biosci. Bioeng., 2008, 106 : 528-536.

In the fuel cell, the electrode 6 according to the present embodiment can be applied to both an anode (fuel electrode) and a cathode (air electrode). In the hydrogen fuel cell, when the electrode 6 according to the present embodiment is an anode, the carbonaceous material 1 catalyzes the reaction of H ₂ → 2H ⁺ + 2e ⁻ of hydrogen gas as a fuel to donate electrons to the anode. . When the electrode 6 according to this embodiment is a cathode, the carbon-based material 1 catalyzes a reaction of 1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O of oxygen gas that is an oxidant. On the other hand, in the MFC, since the anode directly accepts electrons from the electron donating microorganism, the gas diffusion electrode according to the present embodiment is mainly used as a cathode that causes the same electrode 6 reaction as that of the hydrogen fuel cell.

[Example 1]
A mixed solution was prepared by adding pentaethylenehexamine to a 0.1 M iron (III) chloride ethanol solution so as to be 0.15 M. The amount of 0.1 M iron (III) chloride ethanol solution used was adjusted so that the ratio of iron atoms to the amorphous carbon fiber sheet material was 15% by mass.

  The heating temperature of the hot plate was set to 80 ° C., and an amorphous carbon sheet material (non-woven fabric, manufactured by Osaka Gas Chemical Co., Ltd., product name Donakabo Felt LFP-105) having a plan view of 5 cm × 5 cm was placed on the hot plate. Arranged. In this state, the mixed solution was dropped on the sheet material and dried by heating. This obtained the sample containing a sheet material, iron chloride, and pentaethylenehexamine.

  This sample was packed in one end of a quartz tube, and then the inside of the quartz tube was replaced with argon. The quartz tube was pulled out 45 seconds after being placed in a furnace at 900 ° C. When the quartz tube was inserted into the furnace, the quartz tube was inserted into the furnace over 3 seconds to adjust the rate of temperature rise of the sample at the start of heating to 300 ° C./s. Subsequently, the sample was cooled by flowing argon gas through the quartz tube. Thereby, a sheet-like carbon-based material was obtained.

  This carbon-based material was placed in 2M sulfuric acid and stirred at 80 ° C. for 3 hours for acid cleaning. Subsequently, the carbonaceous material was sufficiently rinsed with pure water and then dried in the air.

[Example 2]
In Example 1, a 0.1 M cobalt (II) chloride ethanol solution was used instead of the 0.1 M iron (III) chloride ethanol solution. The amount of the 0.1M cobalt (II) chloride ethanol solution used was adjusted so that the proportion of cobalt atoms with respect to the amorphous carbon fiber sheet material was 20% by mass.

  Otherwise, a carbon-based material was obtained in the same manner and under the same conditions as in Example 1.

[XPS measurement]
The XPS measurement of the carbon-based materials obtained in Examples 1 and 2 was performed under a vacuum condition of 3 × 10 ⁻⁸ Pa using Al characteristic X-rays as a light source. In the measurement, the carbon-based material was fixed by pressing on the In foil. As a result, in any of the Examples, the value of the ratio of metal atoms to carbon atoms was less than 0.01, and the value of the ratio of nonmetal atoms to carbon atoms was less than 0.05.

[X-ray diffraction measurement]
The carbon-based materials obtained in Examples 1 and 2 were acid washed. X-ray diffraction measurement using CuKα rays of this carbon-based material was performed.

  As a result, in any example, the ratio of the peak indicating the impurity to the intensity of the (002) plane peak in the diffraction intensity curve was 0.1 or less.

[Oxygen reduction activity evaluation]
Electrical wiring was connected to the carbon-based material obtained in each of Example 1 and Example 2, and this carbon-based material was used as a working electrode. Using this working electrode, voltammetry was performed while bubbling the electrolyte solution with oxygen gas under the condition of a sweep rate of 5 mV / s using a 1M tris hydrochloride aqueous solution as the electrolyte solution. The resulting voltammograms are shown in FIGS. 3 and 4, respectively.

  According to this voltammogram, in Example 1, it is recognized that the oxygen reduction reaction proceeds from around the electrode potential of 0.8 V (vs. RHE). In Example 2, it is recognized that the oxygen reduction reaction proceeds from around the electrode potential of 0.75 V (vs. RHE). These are all at the highest level for non-platinum oxygen reduction catalysts.

[Evaluation of oxygen reduction activity as a gas diffusion electrode]
A porous polytetrafluoroethylene (PTFE) sheet was stacked on the carbon-based material obtained in Example 1, and the porous PTFE sheet was heated to be fused to the carbon-based material. As a result, an electrode (gas diffusion electrode) including a carbon-based material that is both a gas diffusion layer and an electrode catalyst and a water-repellent layer was obtained.

  Electrical wiring was connected to the carbonaceous material in this electrode, and this electrode was used as a working electrode. Using this working electrode, a 1M tris hydrochloride aqueous solution was used as an electrolytic solution, and voltammetry was performed under a condition of a sweep rate of 5 mV / s while bubbling this electrolytic solution with nitrogen gas. In the measurement, the electrodes were arranged so that the carbon-based material was immersed in the electrolytic solution and the water repellent layer was exposed to the atmosphere. The resulting voltammogram is shown in FIG.

  According to this voltammogram, it is recognized that the oxygen reduction reaction proceeds from around the electrode potential of 0.8 V (vs. RHE). Therefore, it was confirmed that oxygen in the atmosphere reacted on the carbon-based material through the water-repellent layer, that is, the electrode was functioning as a gas diffusion electrode. The performance of this electrode is at the highest level as a non-platinum-based oxygen reducing gas diffusion electrode.

1 Carbon material 2 Sheet material 3 Active layer 6 Electrode

Claims (22)

Having a sheet-like shape,
Amorphous carbon sheet material,
A carbonaceous material provided with the active layer containing a nonmetallic atom containing a 1 type or more atom selected from a nitrogen atom, a boron atom, a sulfur atom, and a phosphorus atom, and a metal atom. The carbon-based material according to claim 1, wherein the sheet material is an amorphous carbon woven or non-woven fabric. The carbon-based material according to claim 1 or 2, which is porous. The carbon-based material according to any one of claims 1 to 3, wherein a surface layer of the sheet material is doped with the nonmetal atoms and the metal atoms, and the active layer is formed on the surface layer. The carbon-based material according to claim 4, wherein a ratio of the metal atom to the carbon atom evaluated by XPS measurement is less than 0.01, and a ratio of the non-metal atom to the carbon atom is less than 0.05. The carbon-based material according to claim 4 or 5, wherein the active layer has a thickness of 1 nm or less. The ratio of the intensity of the maximum peak derived from the inert metal compound and the metal crystal to the intensity of the (002) plane peak in the diffraction intensity curve obtained by X-ray diffraction measurement using CuKα ray is 0. The carbonaceous material according to any one of claims 4 to 6, which is not more than 1. The carbon-based material according to any one of claims 1 to 3, wherein the active layer contains a carbon compound having the non-metal atom and the metal atom. The carbon according to claim 8, wherein the carbon compound contains at least one of an organometallic complex having the nonmetallic atom and the metal atom and a polymer complex having the nonmetallic atom and the metal atom. System material. The carbon-based material according to claim 8 or 9, wherein the active layer is formed by firing the carbon compound. The carbon-based material according to any one of claims 1 to 10, wherein the nonmetallic atom contains a nitrogen atom, and the metallic atom contains at least one of an iron atom and a cobalt atom. The electrode catalyst containing the carbonaceous material as described in any one of Claims 1 thru | or 11. The electrode provided with the carbonaceous material as described in any one of Claims 1 thru | or 11. 14. The electrode according to claim 13, configured as a gas diffusion electrode. The electrode according to claim 13 or 14, further comprising a water-repellent layer overlapping the carbon-based material. The electrode according to claim 15, wherein the water repellent layer is porous. An electrochemical device comprising the electrode according to any one of claims 13 to 16. A fuel cell comprising the electrode according to any one of claims 13 to 16. A nonmetallic compound having a nonmetallic atom including one or more atoms selected from the group consisting of a nitrogen atom, a boron atom, a sulfur atom, and a phosphorus atom, and a metal compound are attached to an amorphous carbon sheet material. Process,
Heating the nonmetallic compound, the metal compound and the sheet material at a temperature in the range of 800 ° C. or higher and 1000 ° C. or lower for a time in the range of 45 seconds or more and less than 600 seconds. Method. The method for producing a carbon-based material according to claim 19, wherein the sheet material is an amorphous carbon woven or non-woven fabric. The method for producing a carbon-based material according to claim 19 or 20, wherein the sheet material is porous. The carbonaceous material manufactured by the method as described in any one of Claims 19 thru | or 21.

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