WO2022186000A1 - Oxyde de graphène réduit poreux et sa méthode de production - Google Patents

Oxyde de graphène réduit poreux et sa méthode de production Download PDF

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WO2022186000A1
WO2022186000A1 PCT/JP2022/007231 JP2022007231W WO2022186000A1 WO 2022186000 A1 WO2022186000 A1 WO 2022186000A1 JP 2022007231 W JP2022007231 W JP 2022007231W WO 2022186000 A1 WO2022186000 A1 WO 2022186000A1
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graphene oxide
reduced graphene
porous
composite
mass
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昌一 孔
ジャオ ジャオ マー
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国立大学法人静岡大学
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/198—Graphene oxide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H01G11/36—Nanostructures, e.g. nanofibres, nanotubes or fullerenes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
    • H01G11/86—Processes for the manufacture of hybrid or EDL capacitors, or components thereof specially adapted for electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/13—Energy storage using capacitors

Definitions

  • the present invention relates to porous reduced graphene oxide and a method for producing the same.
  • the precious metal-free carbon electrodes currently under study have a low energy density and cannot store a large amount of power to be used for long-distance electric vehicles. Therefore, it has become essential to develop a technique for creating a noble metal-free electrode material with a large electrode capacity.
  • Reduced graphene oxide has attracted attention as a noble metal-free electrode material (see Non-Patent Documents 1 and 2).
  • Reduced graphene oxide is a material obtained by reducing graphene oxide obtained by oxidizing graphite. In the reduced graphene oxide, part of the oxygen-containing functional groups of the graphene oxide often remain without being reduced. Therefore, the reduced graphene oxide is intermediate between graphene and graphene oxide. It can be positioned as a material to be located.
  • Non - Patent Document 3 has a problem that the number of steps is large and a long time (for example, 20 hours or more) is required for production. ) is also a problem.
  • porous reduced graphene oxide obtained by the method of Non-Patent Document 3 has a large specific capacity, but there is a demand for the development of a method that can further increase this specific capacity.
  • one of the objects of the present invention is to enable the production of porous reduced graphene oxide by a simpler method.
  • Another object of the present invention is to provide porous reduced graphene oxide having a higher specific capacity and its production.
  • the present inventors have made intensive studies to solve the above problems, and found that a composite containing graphene oxide and metal oxide particles was irradiated with microwaves in the presence of an alcohol and an acid.
  • the present inventors have found that the reduction of graphene oxide and the removal of metal oxide particles can proceed smoothly, and that porous reduced graphene oxide can be obtained efficiently, leading to the completion of the present invention.
  • one aspect of the present invention includes a step a of preparing a composite containing graphene oxide and metal oxide particles, and a step of reducing the graphene oxide in the composite and removing the metal oxide particles from the composite. and b, wherein step b is step b1 of irradiating the complex with microwaves in the presence of an alcohol and an acid, or reducing by irradiating the complex with microwaves in the presence of an alcohol.
  • the present invention relates to a method for producing porous reduced graphene oxide, which is the step b2 of irradiating the reduced composite with microwaves in the presence of an acid after obtaining the composite.
  • graphene oxide can be reduced and pores can be formed in a short process and in a short time, and a special atmosphere or high temperature treatment is not required, so it is simpler than conventional methods. can produce porous reduced graphene oxide.
  • the specific capacity of the obtained porous reduced graphene oxide tends to be larger than in the conventional method. That is, according to the above production method, there is a tendency to obtain a porous reduced graphene oxide having an excellent specific capacity. Although the reason for this is not clear, one possible reason is that the graphene oxide and the metal oxide particles are combined before the reduction of the graphene oxide, so that the aggregation of the graphene caused by the reduction of the graphene oxide is difficult to occur. .
  • the oxygen-containing functional group is excessively reduced by the base, whereas in the above production method, an acid is used to remove the metal oxide particles.
  • step b is preferably step b1 of irradiating the composite with microwaves in the presence of an alcohol and an acid. According to this method, porous reduced graphene oxide can be produced in one pot.
  • the above alcohols may contain alkylene glycol.
  • the reduction of graphene oxide tends to proceed smoothly, and the specific capacity of the obtained porous reduced graphene oxide tends to be larger.
  • the acid may contain at least one selected from the group consisting of hydrochloric acid, sulfuric acid and acetic acid.
  • the graphene oxide is reduced by the microwave heat and the reducing action of the alcohol, and at the same time, the removal of the metal oxide particles from the surface and interlayers of the composite is facilitated.
  • the specific capacity tends to be higher.
  • the content of the metal oxide particles in the composite may be 200 to 500 parts by mass with respect to 100 parts by mass of graphene oxide. In this case, aggregation of graphene is suppressed, and pores having an appropriate amount and shape are likely to be formed, so that the obtained porous reduced graphene oxide tends to have a larger specific capacity.
  • the aggregation of graphene is the aggregation that occurs between graphene layers.
  • Graphene is prone to aggregation between graphene layers due to the influence of ⁇ - ⁇ electrons, and the aggregation not only greatly reduces the specific surface area, but also prevents other substances such as electrolyte ions from entering the graphene layers, resulting in active site limit the amount of Therefore, nonporous reduced graphene oxide tends to have a smaller specific capacity than porous reduced graphene oxide.
  • the porous reduced graphene oxide on the side surface has a higher specific capacitance, it is suitable for use as an electrode material for supercapacitors.
  • an electrode material for a supercapacitor having a large electrode capacity can be obtained.
  • the pore volume of the mesopores may be 0.02-0.4 cm 3 /g, and the pore volume of the macropores may be 0.4-4.0 cm 3 /g. In this case, a larger specific capacity is likely to be obtained.
  • a pore volume of micropores having a pore diameter of less than 10 nm in the porous reduced graphene oxide may be 0.02 cm 3 /g or less. In this case, a larger specific capacity is likely to be obtained.
  • the lower limit of the pore volume of micropores is zero. That is, the porous reduced graphene oxide may not have micropores.
  • porous reduced graphene oxide can be produced by a simpler method.
  • FIG. 2 is an FE-SEM image of zinc oxide particles, reduced graphene oxide, and porous reduced graphene oxide;
  • FIG. 4 is a graph showing pore distribution curves of Example 1 and Comparative Example 1.
  • FIG. 1 is XPS (C1s) spectra of Example 1 and Comparative Example 1.
  • FIG. 1 is XPS (O1s) spectra of Example 1 and Comparative Example 1.
  • a numerical range indicated using "-" indicates a range that includes the numerical values before and after "-" as the minimum and maximum values, respectively.
  • the upper limit or lower limit of the numerical range at one stage may be replaced with the upper limit or lower limit of the numerical range at another stage.
  • the upper limit or lower limit of the numerical range may be replaced with the values shown in the examples.
  • the upper limit value and the lower limit value described individually can be combined arbitrarily.
  • the materials exemplified below may be used singly or in combination of two or more unless otherwise specified.
  • porous reduced graphene oxide of one embodiment is a porous structure including reduced graphene oxide.
  • Porous reduced graphene oxide is, for example, powdery.
  • the porous reduced graphene oxide may be composed only of reduced graphene oxide, and may contain components other than reduced graphene oxide (for example, components that are unavoidably mixed). For example, it may contain a metal that constitutes metal oxide particles or an oxide thereof. These may be those remaining without removing part of the metal or its oxide that constitutes the metal oxide particles used in the production method described below.
  • the amount (e.g., residual amount) of the metal and its oxide in the porous reduced graphene oxide is preferably 3% by mass or less, more preferably 1% by mass, based on the total mass of the porous reduced graphene oxide. % or less, more preferably 0% by mass.
  • the reduced graphene oxide that constitutes the porous reduced graphene oxide is a partially reduced form of graphene oxide. Therefore, the porous reduced graphene oxide has an oxygen-containing functional group (more specifically, the reduced graphene oxide has an oxygen-containing functional group).
  • oxygen-containing functional groups include epoxy group (--COC--), hydroxyl group (--OH), carbonyl group (--CO--), carboxy group (--COOH) and the like.
  • the porous reduced graphene oxide preferably has a carbonyl group as the oxygen-containing functional group.
  • the presence of carbonyl groups in the reduced porous graphene oxide can be confirmed by XPS (X-ray photoelectron spectroscopy) analysis.
  • the C1s spectrum indicates the region corresponding to the energy peak position of the 1s orbital of C in the XPS spectrum
  • the O1s spectrum indicates the region corresponding to the energy peak position of the 1s orbital of O in the XPS spectrum.
  • the energy peak position of the 1s orbital of C and the energy peak of the 1s orbital of O are assigned to either a bond containing C or O based on the peak position.
  • the XPS can be measured by the method described in Examples.
  • the porous reduced graphene oxide preferably has mesopores (pore diameter: 10 nm or more and less than 50 nm) and macropores (pore diameter: 50 nm or more and less than 160 nm). From the viewpoint of obtaining a larger specific capacity, the pore volume of the macropores is preferably larger than the pore volume of the mesopores.
  • the pore volume of the mesopores may be 0.02-0.4 cm 3 /g, 0.05-0.3 cm 3 /g or 0.1-0. It may be 25 cm 3 /g.
  • the pore volume of mesopores can be measured by the method described in Examples.
  • the pore volume of the macropores may be 0.4-4.0 cm 3 /g, 0.7-3.5 cm 3 /g or 1.0-3. It may be 0 cm 3 /g.
  • the pore volume of macropores can be measured by the method described in Examples.
  • the porous reduced graphene oxide may have pores (micropores) with a pore diameter of less than 10 nm.
  • the pore volume of micropores may be smaller than the pore volume of mesopores, for example 0.02 cm 3 /g or less.
  • the pore volume of the micropores may be 0.001-0.02 cm 3 /g.
  • the porous reduced graphene oxide may have pores with a pore diameter of 160 nm or more.
  • porous reduced graphene oxide described above can be suitably used as a noble metal-free conductive material, and in particular can be suitably used as an electrode material for supercapacitors.
  • the above porous reduced graphene oxide can be obtained by a method for producing porous reduced graphene oxide, which will be described later.
  • a method for producing porous reduced graphene oxide comprises a step a of preparing a composite containing graphene oxide and metal oxide particles, reducing the graphene oxide in the composite, and oxidizing the metal from the composite. and b. removing the particles.
  • step a a composite is provided.
  • the composite includes at least graphene oxide (GO) and metal oxide (ZnO) particles.
  • Graphene oxide can be obtained, for example, by oxidizing graphite by the Hummers method described in Non-Patent Document 1.
  • the Hummers method generally comprises a step of pretreating graphite by reaction with a compound selected from ammonium persulfate, diphosphorus pentoxide and sulfuric acid (first step), and treating the pretreated graphite with sulfuric acid and a strong oxidizing agent (e.g. potassium permanganate) (second step).
  • first step a compound selected from ammonium persulfate, diphosphorus pentoxide and sulfuric acid
  • a strong oxidizing agent e.g. potassium permanganate
  • the pretreated graphite is washed with water and dried before being subjected to the second step.
  • the graphite (graphene oxide) oxidized in the second step may be washed with hydrogen peroxide, hydrochloric acid, water, or the like. According to this method, powdery graphene oxide is obtained.
  • Graphene oxide has oxygen-containing functional groups generated by oxidizing graphite.
  • the oxygen-containing functional group is, for example, an epoxy group (-COC-), a hydroxyl group (-OH), a carbonyl group (-CO-), and at least one functional group selected from the group consisting of a carboxyl group (-COOH). can contain.
  • the content of graphene oxide in the composite is preferably 17% by mass or more, more preferably 18% by mass or more, and still more preferably 19% by mass or more, based on the total mass of the composite. Preferably, it is 20% by mass or more. When the content of graphene oxide is 17% by mass or more, porous reduced graphene oxide having a higher specific capacity can be easily obtained.
  • the content of graphene oxide in the composite is preferably 34% by mass or less, more preferably 32% by mass or less, still more preferably 29% by mass or less, based on the total mass of the composite, and particularly Preferably, it is 25% by mass or less.
  • the content of graphene oxide is 34% by mass or less, aggregation of graphene is easily suppressed, and porous reduced graphene oxide having a larger specific capacity is easily obtained. From these points of view, the content of graphene oxide is preferably 17 to 34% by mass based on the total mass of the composite.
  • a metal oxide particle is a particle whose main component is a metal oxide.
  • the metal oxide particles are composited with graphene oxide while being dispersed in the graphene oxide.
  • metal oxide particles may be linked to graphene oxide through non-covalent interactions (eg, electrostatic interactions acting between positive and negative charges).
  • the metal oxide is not particularly limited as long as it can form a composite with graphene oxide through non-covalent interactions.
  • the metal oxide is preferably zinc oxide (ZnO), magnesium oxide (MgO), calcium oxide (CaO), lead oxide (PbO) or mercury oxide (HgO), more preferably zinc oxide.
  • the metal oxide particles may contain components other than metal oxides (for example, components that are unavoidably mixed).
  • the content of the metal oxide in the metal oxide particles is preferably 90% by mass or more, more preferably 95% by mass or more, and still more preferably 99% by mass or more.
  • the metal oxide particles may consist of metal oxide only.
  • the content of zinc oxide in the metal oxide may be in the above range
  • the content of magnesium oxide may be in the above range
  • the content of calcium oxide may be in the above range.
  • the content of lead oxide may be within the above range
  • the content of mercury oxide may be within the above range.
  • the shape of the metal oxide particles may be spherical, or may be non-spherical such as scale-like or rod-like.
  • the porous reduced graphene oxide tends to exhibit a large specific capacity when it has mesopores with a pore diameter of 10 nm or more and less than 50 nm and macropores with a pore diameter of 50 nm or more and less than 160 nm.
  • the average particle size of the metal oxide particles is preferably 2 to 500 nm from the viewpoint of easily obtaining the porous reduced graphene oxide having mesopores and macropores.
  • the average particle size of the metal oxide particles may be 10 nm or more, 50 nm or more, 100 nm or more, 200 nm or more, or 250 nm or more, and 500 nm or less, 400 nm or less, or 300 nm or less. Alternatively, it may be 250 nm or less.
  • the average particle diameter of the metal oxide particles is 50 nm or more, the pore volume of macropores tends to be larger than the pore volume of mesopores.
  • the average particle diameter means the average diameter of the particles when the shape of the metal oxide particles is spherical, and the longest portion (major diameter) of the particles when the shape of the metal oxide particles is non-spherical. means the average value of Also, the average particle size is obtained by measuring the diameter or length of 100 particles using a scanning electron microscope (SEM) and calculating the average value.
  • SEM scanning electron microscope
  • the content of the metal oxide particles in the composite is preferably 200 parts by mass or more, more preferably 250 parts by mass or more, and still more preferably 300 parts by mass or more with respect to 100 parts by mass of graphene oxide. In this case, aggregation of graphene is unlikely to occur, and porous reduced graphene oxide having a large specific capacity can be easily obtained.
  • the content of the metal oxide particles in the composite is preferably 500 parts by mass or less, more preferably 450 parts by mass or less, and still more preferably 400 parts by mass or less with respect to 100 parts by mass of graphene oxide. In this case, pores having an appropriate amount and shape are likely to be formed, so that the obtained porous reduced graphene oxide tends to have a larger specific capacity. From these points of view, the content of the metal oxide particles in the composite is preferably 200 to 500 parts by mass with respect to 100 parts by mass of graphene oxide.
  • the complex is, for example, powdery.
  • the composite can be obtained, for example, by dispersing metal oxide particles in a solution containing graphene oxide, subjecting to ultrasonic treatment, filtering and drying.
  • the solvent of the solution include water, ethanol, and the like.
  • the amount of the solvent may be 30,000 to 200,000 parts by weight with respect to 100 parts by weight of graphene oxide.
  • Ultrasonic treatment can be performed using an ultrasonic generator such as an ultrasonic cleaner (M2800HJ) manufactured by Yamato Scientific Co., Ltd., for example. Sonication may be performed below 0° C. (eg in an ice bath). The duration of sonication may be from 0.5 to 2 hours.
  • a stirring treatment may be performed after the metal oxide particles are dispersed and after the ultrasonic treatment. The stirring treatment after dispersing the metal oxide particles may be performed for 12 to 36 hours. Stirring treatment after ultrasonic treatment may be performed for 0.5 to 2 hours. Drying may be carried out at 35-80° C. for 6-24 hours.
  • step b the graphene oxide is reduced and the metal oxide particles are removed from the composite to obtain porous reduced graphene oxide.
  • the reduction of graphene oxide and the removal of the metal oxide particles may proceed simultaneously, or the removal of the metal oxide particles may be performed after the reduction of the graphene oxide. That is, the step b may be a step b1 of irradiating the complex with microwaves in the presence of an alcohol and an acid, and irradiating the complex with microwaves in the presence of an alcohol to form a reduced complex After obtaining, a step b2 of irradiating the reduced complex with microwaves in the presence of an acid may be performed.
  • the step b is the step b1 from the viewpoint that the reduction of the graphene oxide in the composite and the removal of the metal oxide particles from the composite can proceed in one pot, and the porous reduced graphene oxide can be produced more easily. is preferred.
  • the step b1 there is a tendency to obtain porous reduced graphene oxide with a larger specific capacity.
  • alcohols Since alcohols have reducing properties, they function as reducing agents in step b (step b1 and step b2).
  • examples of alcohols include alcohols such as propanol and butanol, and alkylene glycols such as ethylene glycol, methylene glycol, propylene glycol and trimethylene glycol.
  • alkylene glycol is preferably used from the viewpoint that the reduction of graphene oxide tends to proceed moderately and the specific capacity of the obtained porous reduced graphene oxide tends to be larger, and ethylene glycol, methylene glycol, and propylene are used. At least one selected from the group consisting of glycol and trimethylene glycol is more preferably used.
  • the acid may be an organic acid or an inorganic acid.
  • the acid at least one selected from the group consisting of hydrochloric acid (HCl), sulfuric acid (H 2 SO 4 ) and acetic acid (CH 3 COOH) is preferably used from the viewpoint of easy removal of metal oxides.
  • the acid is usually used in the form of an aqueous solution mixed with water. That is, in step b, an aqueous solution containing an acid (for example, dilute hydrochloric acid, dilute sulfuric acid, dilute acetic acid, etc.) may be used.
  • Step b1 reduced graphene oxide is formed by reducing graphene oxide by the reducing action of alcohols and microwaves, and the metal oxide particles are removed from the composite by the action of acid.
  • Step b1 is, for example, a step of adding a complex to a solution (e.g., aqueous solution) containing an alcohol and an acid to obtain a complex-containing solution, and then irradiating the obtained complex-containing solution with microwaves. good.
  • a solution e.g., aqueous solution
  • the amount of alcohol used may be 1000 to 3000 parts by mass with respect to 100 parts by mass of the composite.
  • the concentration of alcohols in the solution may be 40 to 90% by weight based on the total weight of the solution.
  • the amount of acid used may be 70 to 600 parts by mass with respect to 100 parts by mass of the composite.
  • the acid concentration in the solution may be 10 to 30% by weight based on the total weight of the solution.
  • the amount of the complex added may be 1 to 10% by mass based on the total mass of the complex-containing solution.
  • Microwave irradiation can be performed, for example, using a microwave generator such as a microwave oven (Discover SP manufactured by CEM Corporation).
  • a microwave generator such as a microwave oven (Discover SP manufactured by CEM Corporation).
  • the output of the microwave varies depending on the irradiation time of the microwave, the amount of the object to be treated (for example, the complex-containing solution), the size of the device, etc., but can be, for example, 50 to 300W.
  • the microwave irradiation time can be, for example, 2 to 30 minutes.
  • the microwave frequency can be, for example, 915 MHz to 2455 MHz.
  • the microwave irradiation may be performed at room temperature (eg, 25°C) or may be performed while heating.
  • the environmental temperature (for example, the set temperature in the microwave generator) during microwave irradiation may be 25 to 200°C, 100 to 200°C, or 150 to 180°C.
  • the porous reduced graphene oxide After the microwave irradiation, after filtering the obtained solution containing the porous reduced graphene oxide, the porous reduced graphene oxide may be washed (for example, washed with water) and dried.
  • the drying temperature may be 40-100° C. and the drying time may be 8-24 hours.
  • Step b2 includes step b2-1 of irradiating the above complex with microwaves in the presence of an alcohol to obtain a reduced complex, and step b2- of irradiating the reduced complex with microwaves in the presence of an acid. 2.
  • step b2-1 reduced graphene oxide is formed by reducing graphene oxide by the reducing action of alcohols and microwaves. That is, the reduced composite obtained in step b2-1 is a composite containing reduced graphene oxide and metal oxide particles.
  • the complex is put into a solution (eg, aqueous solution) containing an alcohol to obtain a first complex-containing solution, and then microwaves are applied to the obtained first complex-containing solution. It may be a step of irradiating. Part or all of the metal oxide particles may be reduced in step b2-1. That is, the reduced complex may contain zinc.
  • the amount of alcohol used in step b2-1 (based on 100 parts by mass of complex) may be the same as the amount of alcohol used in step b1 (based on 100 parts by mass of complex).
  • the concentration of alcohols in the solution may be 40% by mass or more, or may be 100% by mass, based on the total mass of the solution.
  • step b2-2 the metal oxide is removed from the reduced composite by the action of acid to form porous reduced graphene oxide.
  • the reduced complex is added to a solution (eg, aqueous solution) containing an acid to obtain a second complex-containing solution, and then the obtained second complex-containing solution is irradiated with microwaves. It may be a step of
  • the amount of acid used in step b2-2 (based on 100 parts by mass of the reduced complex) may be the same as the amount of acid used in step b1 (based on 100 parts by mass of the complex).
  • the acid concentration in the solution may be 10-30% by weight based on the total weight of the solution.
  • microwave irradiation in steps b2-1 and b2-2 can be performed using the same equipment as in step b-1 under the same conditions as in step b-1.
  • the solution containing the product (reduced composite or porous reduced graphene oxide) is filtered in the same manner as in step b-1, and then the product Items may be washed and dried.
  • step b some or all of the oxygen-containing functional groups of graphene oxide are reduced.
  • some of the oxygen-containing functional groups are reduced that is, some of the oxygen-containing functional groups are not reduce
  • the degree of reduction of graphene oxide can be adjusted depending on the type of alcohol, microwave irradiation conditions, and the like.
  • porous reduced graphene oxide by a simpler method than the conventional method.
  • the porous reduced graphene oxide produced by the method of the present embodiment tends to have a larger specific capacity than the porous reduced graphene oxide produced by the conventional method.
  • porous reduced graphene oxide produced by the method of the present embodiment will be described below.
  • the porous reduced graphene oxide produced by the method of the present embodiment may be composed only of reduced graphene oxide, and may contain components other than reduced graphene oxide (for example, components that are unavoidably mixed). good too.
  • part of the metal constituting the metal oxide particles or its oxide may remain in the porous reduced graphene oxide without being removed.
  • the residual amount of the metal and its oxide in the porous reduced graphene oxide is preferably 3% by mass or less, more preferably 1% by mass or less, based on the total mass of the porous reduced graphene oxide. , and more preferably 0% by mass.
  • the porous reduced graphene oxide produced by the method of the present embodiment preferably has oxygen-containing functional groups.
  • the porous reduced graphene oxide preferably has a carbonyl group (—CO—) as an oxygen-containing functional group.
  • —CO— carbonyl group
  • XPS can be measured by the method described in Examples.
  • the porous reduced graphene oxide produced by the method of the present embodiment preferably has mesopores (pore diameter: 10 nm or more and less than 50 nm) and macropores (pore diameter: 50 nm or more and less than 160 nm).
  • the pore volume of the mesopores may be between 0.02 and 0.4 cm 3 /g.
  • the pore volume of mesopores can be measured by the method described in Examples.
  • the porous reduced graphene oxide produced by the method of the present embodiment is usually powdery. If the powder is agglomerated and clumped, it may be pulverized into fine powder before use.
  • the porous reduced graphene oxide produced by the method of the present embodiment can be suitably used as a noble metal-free conductive material, and can be particularly suitably used as an electrode material for supercapacitors.
  • Graphene oxide (GO) was synthesized from graphite powder (average particle size: 45 ⁇ m) by a modified Hummers method. Specifically, first, 60 ml of sulfuric acid (H 2 SO 4 , 95% by mass) was added to a 500 ml beaker and heated to 80°C. To this, 3.0 g of ammonium persulfate ((NH 4 ) 2 S 2 O 8 , 98% by mass) was added with stirring and dissolved to obtain a solution.
  • sulfuric acid H 2 SO 4 , 95% by mass
  • the ice bath was then removed and the solution was stirred for 2 hours while maintaining the temperature below 35°C.
  • 750 ml of DI water was added to the stirred solution, 10 ml of hydrogen peroxide (H 2 O 2 , 30% by mass) was added, and the mixture was stirred for 2 hours and allowed to stand overnight.
  • the supernatant was filtered to obtain a filter paper sediment and a sediment at the bottom of the beaker (beaker sediment).
  • the resulting filter paper sediment and beaker sediment were placed in the same beaker, 250 ml of hydrochloric acid (10% by mass) was added, and the mixture was stirred for 2 hours and then filtered.
  • the filter paper precipitate and the beaker precipitate were dissolved in 250 ml of DI water to prepare an aqueous solution containing graphene oxide (GO aqueous solution).
  • Example 2 Powdery porous reduction was performed in the same manner as in Example 1, except that the GO aqueous solution and ZnO particles were used so that the GO:ZnO particles (mass ratio) in the powdery GO/ZnO composite was 1:3. type graphene oxide (prGO) was obtained.
  • Example 3 A powdery GO/ZnO composite was produced in the same manner as in Example 1. Next, 0.238 g of the powdery GO/ZnO composite was put into a container to which 3 ml of ethylene glycol was added to obtain a first composite-containing solution. Microwave irradiated. Microwave irradiation was performed continuously for 6 minutes under conditions of a frequency of 2455 MHz, an output of 100 W, and an ambient temperature of 180° C. using a microwave oven (manufactured by CEM Corporation, product name: Discover SP). As a result, a solution containing an rGO/ZnO composite (a composite containing reduced graphene oxide (rGO) and ZnO particles) was obtained. The resulting solution was filtered, the filtrate was washed with DI water to remove residual impurities, and the washed filtrate was dried at 40° C. overnight to obtain a powdery rGO/ZnO composite. .
  • Example 2 In the same manner as in Example 1, except that the GO-containing solution was used instead of the composite solution, the GO-containing solution was irradiated with microwaves, filtered, washed and dried to obtain powdery reduced graphene oxide ( rGO) was obtained.
  • FIG. 1(a) shows ZnO particles
  • FIG. 1(b) shows rGO
  • FIGS. 1(c) and 1(d) show prGO.
  • FIG. 1(d) is an enlarged image of FIG. 1(c).
  • the ZnO particles used were of rod-like cubic shape, and in prGO, the pores (mesopores and macropores) corresponding to the ZnO particles were unevenly distributed between the layers of the prGO sheet with wrinkled surfaces. It was confirmed that they were formed so as to be uniformly distributed.
  • the prGO of Examples 2 and 3 was also subjected to morphological observation using FE-SEM, and it was confirmed that the prGO of Example 1 had the same morphology.
  • FIG. 2 is a graph showing the pore size distribution curves of prGO of Example 1 and rGO of Comparative Example 1, determined based on the measured N 2 adsorption/desorption isotherms.
  • the horizontal axis in FIG. 2 indicates the pore diameter, and the vertical axis indicates the value obtained by dividing the differential pore volume (dV) by the logarithmic differential value d (logD) of the pore diameter.
  • the pores of prGO are mainly distributed from 10 to 160 nm, and the distribution of pores is mainly concentrated in macropores (50 nm or more and less than 160 nm) corresponding to the size of ZnO particles. .
  • the enlarged view enlarged view of the region with a pore diameter of 10 nm or less
  • the pore volume of micropores of the porous reduced graphene oxide (prGO) obtained in Example 1 is 0.007 cm 3 /g
  • the pore volume of mesopores is 0.20 cm 3 /g.
  • the pore volume of the macropores was 1.8 cm 3 /g.
  • the pore volume of the micropores of the reduced graphene oxide (rGO) obtained in Comparative Example 1 was 0.002 cm 3 /g, and the pore volume of the mesopores was 0.006 cm 3 /g.
  • the pore volume of the pores was 0.02 cm 3 /g.
  • the obtained prGO or rGO is pulverized into a fine powder to prepare a measurement sample, immersed in a 0.1% Nafion solution (“nafion” is a registered trademark), and then the resulting mixture is subjected to ultrasonic treatment for several minutes.
  • a 0.1% Nafion solution (“nafion” is a registered trademark)
  • the resulting solution was then deposited on a glassy carbon electrode (GCE) by dropping it using a micropipette to prepare a working electrode.
  • cyclic voltammetry (CV) measurements and galvanostatic charge-discharge (GCD) measurements were performed using the prepared working electrode.
  • a platinum wire electrode and a saturated calomel (Hg/HgCl 2 ) electrode were used as a counter electrode and a reference electrode, respectively.
  • the measurement was performed using a BioLogic SP300-SK-S electrochemical workstation at room temperature in a 1 M H 2 SO 4 aqueous solution electrolyte, with a potential window of 0 to 1 V and a scan rate of 5 to 200 mV. /s, and the current density was 1 to 10 A/g.

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Abstract

L'invention concerne un oxyde de graphène réduit poreux qui est une structure poreuse qui comprend de l'oxyde de graphène réduit et a des mésopores ayant un diamètre de pore supérieur ou égal à 10 nm mais inférieur à 50 nm et des macropores qui ont un diamètre de pore supérieur ou égal à 50 nm mais inférieur à 160 nm. Dans un spectre C1s mesuré à l'aide de XPS, la proportion de liaisons attribuées à C = O est de 3 % à 10 % ; dans un spectre O1s mesuré à l'aide de XPS, la proportion de liaisons attribuées à C = O est de 25 % à 55 % ; et le volume poreux des macropores est supérieur au volume poreux des mésopores.
PCT/JP2022/007231 2021-03-03 2022-02-22 Oxyde de graphène réduit poreux et sa méthode de production WO2022186000A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108584938A (zh) * 2018-06-11 2018-09-28 中国科学院高能物理研究所 一种多孔氧化石墨烯的制备方法
JP2019513682A (ja) * 2016-04-13 2019-05-30 グリーン ナノテク ラブズ，エルエルシー グラフェンおよび酸化グラフェンを炭素リッチ天然材料を用いて量産するための低コストかつ迅速な方法
CN111039283A (zh) * 2020-01-16 2020-04-21 中原工学院 一种微波辅助制备金属氧化物/石墨烯纳米结构材料及制备方法
CN112093795A (zh) * 2020-09-22 2020-12-18 广东极客亮技术有限公司 蜂窝状多孔石墨烯及其制备方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019513682A (ja) * 2016-04-13 2019-05-30 グリーン ナノテク ラブズ，エルエルシー グラフェンおよび酸化グラフェンを炭素リッチ天然材料を用いて量産するための低コストかつ迅速な方法
CN108584938A (zh) * 2018-06-11 2018-09-28 中国科学院高能物理研究所 一种多孔氧化石墨烯的制备方法
CN111039283A (zh) * 2020-01-16 2020-04-21 中原工学院 一种微波辅助制备金属氧化物/石墨烯纳米结构材料及制备方法
CN112093795A (zh) * 2020-09-22 2020-12-18 广东极客亮技术有限公司 蜂窝状多孔石墨烯及其制备方法

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