CN115966706A - Hierarchical porous graphene material and preparation method and application thereof - Google Patents
Hierarchical porous graphene material and preparation method and application thereof Download PDFInfo
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Abstract
The invention relates to the technical field of novel nano carbon materials, and discloses a hierarchical pore graphene material, and a preparation method and application thereof. The pore structure of the graphene material contains micropores and mesopores, and the multi-level pore structure and the multi-level pores have synergistic effect, so that the graphene material shows good catalytic activity when being applied to a fuel cell catalyst carrier and/or a fuel cell catalyst. In addition, the preparation method of the graphene material is simple and efficient, the transition metal salt, the alkali metal salt and/or alkali and the carbon source can be directly mixed to prepare the precursor material at normal temperature and normal pressure, a high-temperature high-pressure reaction kettle is not required to be used for self-assembly, a large amount of organic solvent is not required to be used, only the carbon source is consumed in the whole process, metal atoms can be recycled, and the preparation cost is low.
Description
Technical Field
The invention relates to the technical field of novel nano carbon materials, in particular to a hierarchical pore graphene material, a preparation method thereof and application of the hierarchical pore graphene material in a fuel cell catalyst carrier and/or a fuel cell catalyst.
Background
Graphene is a polymer consisting of carbon atoms in sp 2 The hybridized orbit forms a hexagonal honeycomb lattice two-dimensional carbon nano material. The material has excellent optical, electrical and mechanical properties, has important application prospects in the aspects of materials science, micro-nano processing, energy, biomedicine, drug delivery and the like, and is considered to be a revolutionary material in the future. However, since the graphene is a two-dimensional material, graphene sheets are easy to agglomerate, and the application of the graphene sheets in the macro is limited, so that more nano graphite carbon materials with novel structures, such as graphite carbon nano cups, nano corners, nano rings, nano cages and the like, have been developed in succession. The appearance of the materials enriches the structure of the nano graphite carbon material, and opens a wider space for the application of the nano graphite carbon material.
The graphene nano cage is a very unique novel nano graphite structure, has a unique hollow structure similar to fullerene and controllable nano size, can endow the material with a series of unique physical and chemical properties, and is expected to be applied to various fields such as industrial catalysis, electrochemical energy storage, drug carriers, optical devices and the like.
Generally, the preparation method of the graphene nanocage mainly comprises a laser sputtering method, an arc discharge method, a supercritical fluid method, a chemical vapor deposition method and the like. These methods mostly require metallic particles synthesized in advance as a template, an expensive carbon-containing atmosphere (such as methane, acetylene, etc.) as a carbon source, and a high-purity inert gas (such as nitrogen, argon, etc.) as a protective gas. Due to the technical limitation, the equipment used in the methods has a complex structure, high price, complex operation and high energy consumption, and the prepared graphene nanocages have irregular shapes and are difficult to realize effective regulation and control of the shapes; the prepared nanocages are large in size, and are generally larger than 100nm; meanwhile, the material has the defects of more defects, high resistivity, poor conductivity and the like.
The hierarchical pore material has the advantages of good permeability, developed pore structure, large specific surface area and pore volume and the like, and breaks through the limitation of single pore structure of the traditional single-level pore material, so that the hierarchical pore material is more and more concerned by researchers. The hierarchical porous material mainly comprises micropore-mesopore, mesopore-macropore, micropore-mesopore-macropore and mesopore material containing two or more than two kinds of different pore diameters. The microporous-mesoporous material has wide application prospect in the aspects of gas/liquid separation, water purification treatment, catalyst carriers, adsorption, energy storage, super electrical appliances and the like. The main preparation methods include a chemical activation method, a template method, a hydrothermal method and the like. But the preparation process still has the defects of uneven pore size distribution, complex preparation process, higher cost and the like.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a hierarchical porous graphene material, a preparation method thereof and application of the hierarchical porous graphene material in a fuel cell catalyst carrier and/or a fuel cell catalyst. The graphene material provided by the invention has a hierarchical pore structure, good conductivity and low preparation cost.
In order to achieve the above object, a first aspect of the present invention provides a hierarchical pore graphene material, which has a pore size distribution curve having both a micropore distribution peak and a mesopore distribution peak, and has a resistivity lower than 1100m Ω · cm.
The second aspect of the present invention provides a preparation method of a hierarchical porous graphene material, including the following steps:
(1) Providing a solution containing a transition metal salt, a salt containing an alkali metal and/or an alkali and a carbon source, and then drying to obtain a precursor material;
(2) Pyrolyzing the precursor material obtained in the step (1) in an inert atmosphere or a reducing atmosphere to obtain a pyrolysis product;
(3) And (3) carrying out acid washing on the pyrolysis product, and then carrying out solid-liquid separation and drying.
In a third aspect of the present invention, the application of the hierarchical porous graphene material described in the first aspect or the hierarchical porous graphene material prepared by the method described in the second aspect in a fuel cell catalyst carrier and/or a fuel cell catalyst is provided.
Through the technical scheme, the invention has the following advantages:
(1) The hierarchical pore graphene material provided by the invention has a micropore distribution peak and a mesopore distribution peak in a pore diameter distribution curve, has a hierarchical pore structure, has low resistivity, is lower than 1100m omega cm, and has good conductivity. The pore structure of the graphene material contains micropores and mesopores, and the multi-level pore structure and the multi-level pores have synergistic effect, so that the graphene material shows good catalytic activity when being applied to a fuel cell catalyst carrier and/or a fuel cell catalyst;
(2) The preparation method of the hierarchical porous graphene material provided by the invention is simple and efficient, the transition metal salt, the alkali metal salt and/or alkali and the carbon source can be directly mixed to prepare the precursor material at normal temperature and normal pressure, the self-assembly of a high-temperature high-pressure reaction kettle is not needed, a large amount of organic solvent is not needed, only the carbon source is lost in the whole process, the metal atoms can be recycled, and the preparation cost is low.
Drawings
Fig. 1 is a pore volume-pore size distribution curve of the hierarchical pore graphene material prepared in example 1;
fig. 2 is a TEM image of the multi-level pore graphene material prepared in example 1;
fig. 3 is an XPS chart of the multi-level pore graphene material prepared in example 1;
fig. 4 is a TEM image of the multi-level pore graphene material prepared in example 2;
fig. 5 is an XPS plot of the multi-level pore graphene material prepared in example 2;
fig. 6 is a TEM image of the multi-level pore graphene material prepared in example 3;
fig. 7 is a TEM image of the multi-level pore graphene material prepared in example 4;
fig. 8 is a TEM image of the multi-level pore graphene material prepared in example 5;
fig. 9 is a TEM image of a multi-level pore graphene material prepared in example 6;
fig. 10 is a TEM image of the multi-level pore graphene material prepared in example 7;
fig. 11 is a TEM image of the multi-level pore graphene material prepared in example 8;
fig. 12 is a TEM image of the carbon material prepared in comparative example 1.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
In the present invention, the term "mesoporous" is defined as pores having a pore diameter in the range of 2 to 50nm, "microporous" is defined as pores having a pore diameter of less than 2nm, and "macroporous" is defined as pores having a pore diameter of more than 50nm.
In the present invention, the term "mesopore distribution peak" refers to a mesopore distribution peak on a pore distribution curve calculated from a desorption curve according to the Barrett-Joyner-Halenda (BJH) method.
In the present invention, the term "micropore distribution peak" refers to a micropore distribution peak on a pore distribution curve calculated from an isothermal curve according to the Horvath-Kawazoe (HK) method.
The invention provides a hierarchical pore graphene material, wherein a pore size distribution curve of the graphene material simultaneously has a micropore distribution peak and a mesopore distribution peak, and the resistivity of the graphene material is lower than 1100m omega cm.
According to some embodiments of the present invention, preferably, in the pore size distribution curve of the graphene material, at least one mesopore distribution peak exists at 2 to 50nm, and preferably two mesopore distribution peaks exist at 2.3 to 4nm and 3.5 to 40 nm.
According to some embodiments of the present invention, preferably, in the pore size distribution curve of the graphene material, at least one micropore distribution peak is present at 0.4 to 1 nm.
According to some embodiments of the present invention, preferably, in the pore size distribution curve of the graphene material, there are two micropore distribution peaks at 0.4 to 0.6nm and 0.5 to 0.8 nm.
According to some embodiments of the present invention, preferably, in the pore size distribution curve of the graphene material, there are three micropore distribution peaks at 0.4 to 0.6nm, 0.45 to 0.65nm, and 0.5 to 0.8 nm.
The graphene material has a hierarchical pore structure, the pore structure of the graphene material contains micropores and mesopores, and the hierarchical pore structure and the hierarchical pores have synergistic effects, so that the graphene material has higher electrochemical catalytic activity when being applied to a fuel cell catalyst carrier and/or a fuel cell catalyst.
According to some embodiments of the invention, the resistivity of the graphene material is lower than 1100m Ω · cm, preferably the resistivity of the graphene material is 50-1000m Ω · cm, more preferably 60-600m Ω · cm. The resistivity and the conductivity of the graphene material provided by the invention can be regulated and controlled according to different application fields.
In the invention, the resistivity of the graphene material is measured according to a method for measuring the resistivity of carbon raw materials and coke in the national standard GB/T2459-018, and a used instrument is an ST-2722 type semiconductor powder resistivity tester produced by Suzhou lattice electronics Limited.
In the invention, the pore structure property of the graphene material is determined by a Quantachrome AS-6B type analyzer.
According to some embodiments of the present invention, preferably, the graphene material has a specific surface area of 100 to 1500m 2 (g) micropore area of 2-1000m 2 (ii)/g, total pore volume of 0.3-1.5cm 3 /g。
More preferably, the specific surface area of the graphene material is 300-1500m 2 Per g, the micropore area is 100-800m 2 (ii)/g, total pore volume of 0.4-1.2cm 3 (ii) in terms of/g. The graphene material has a high specific surface area.
In the invention, the specific surface area, the micropore area and the pore volume of the graphene material are obtained by a Brunauer-Emmett-Taller (BET) method.
According to some embodiments of the present invention, preferably, the graphene material has a molar content of carbon element of 90 to 98% and a molar content of oxygen element of 2 to 10% as determined by X-ray photoelectron spectroscopy.
More preferably, the graphene material has a molar content of carbon element of 91-97% and a molar content of oxygen element of 3-8% as determined by X-ray photoelectron spectroscopy.
According to some embodiments of the present invention, preferably, the graphene material may further include nitrogen, which may be in various forms formed in the multi-level pore graphene material and introduced by using a nitrogen-containing compound as a carbon source during the preparation of the multi-level pore graphene material. More preferably, the graphene material has a nitrogen element content of 0.2 to 5% by mole as measured by X-ray photoelectron spectroscopy.
According to some embodiments of the present invention, the hierarchical porous graphene material may contain various doping elements known to those skilled in the art to be applicable to carbon materials, and preferably, the hierarchical porous graphene material does not contain iron, cobalt, nickel, copper, boron, phosphorus, fluorine, chlorine, bromine, iodine, sulfur, and other elements.
According to some embodiments of the present invention, preferably, the content of oxygen element determined by a peak corresponding to a C — O group and the content of oxygen element determined by a peak corresponding to a C — O group in an X-ray photoelectron spectrum of the graphene material are different from each other
The molar ratio of the content of oxygen element determined by the peak of the group is 0.6-5:1, preferably0.8-3:1. under the preferred embodiment, the prepared hierarchical porous graphene material has rich oxygen functional groups on the surface, and has higher electrochemical catalytic activity when being applied to a fuel cell catalyst.
In the invention, the contents of elements and oxygen species on the surface of the hierarchical porous graphene material are measured by X-ray photoelectron spectroscopy (XPS), the X-ray photoelectron spectroscopy is carried out on an ESCALab250 type X-ray photoelectron spectrometer which is provided with Thermo Avantage V5.926 software and manufactured by Thermo Scientific company, an excitation source is monochromatized Al K alpha X-ray, the energy is 1486.6eV, the power is 150W, the penetrating energy used by narrow scanning is 30eV, and the basic vacuum during analysis and test is 6.53 multiplied by 10 -9 mbar, electron binding energy was corrected with the C1s peak (284.6 eV) of elemental carbon, data processed on Thermo Avantage software, and quantitative analysis was performed in the analysis module using the sensitivity factor method.
According to some embodiments of the present invention, preferably, in a raman curve of the graphene material, I D /I G In the range of 0.1 to 1.2, preferably 0.17 to 1. In the Raman curve of the graphene material, I D /I G Refers to the ratio of the intensities of the D and G peaks in the raman curve. The graphene material disclosed by the invention has obvious D peak and G peak and has higher graphitization degree. In the invention, the Raman spectrum is obtained by using RM2000 type micro confocal Raman spectrometer (product of Reinshaw company), and the technical indexes are as follows: the excitation source is He-Ne laser with wavelength of 525 nm.
According to some embodiments of the present invention, preferably, a graphitized carbon layer is further present in the graphene material, and the graphene material has a hollow cage structure composed of interwoven graphitized carbon layers. More preferably, the number of the graphitized carbon layers of the graphene material is 1 to 10.
According to some embodiments of the present invention, preferably, the graphene material has a diameter of 2 to 100nm, preferably 5 to 50nm.
In the invention, a high-resolution transmission electron microscope (HRTEM) is adopted to observe and determine the morphology of the graphene material, and the diameter of the graphene material and the number of the graphitized carbon layers are measured by the high-resolution transmission electron microscope (HRTEM).
The second aspect of the present invention provides a preparation method of a hierarchical pore graphene material, including the following steps:
(1) Providing a solution containing a transition metal salt, a salt containing an alkali metal and/or an alkali and a carbon source, and then drying to obtain a precursor material;
(2) Pyrolyzing the precursor material obtained in the step (1) in an inert atmosphere or a reducing atmosphere to obtain a pyrolysis product;
(3) And (3) carrying out acid washing on the pyrolysis product, and then carrying out solid-liquid separation and drying.
According to some embodiments of the invention, the preparation method is simple and efficient, the precursor material can be prepared by directly mixing the transition metal salt, the alkali metal salt and/or the alkali and the carbon source at normal temperature and normal pressure, the self-assembly of a high-temperature high-pressure reaction kettle is not needed, a large amount of organic solvent is not needed, only the carbon source is consumed in the whole process, the metal atoms can be recycled, and the preparation cost is low. The hierarchical pore graphene material prepared by the preparation method has a hierarchical pore structure, a pore diameter distribution curve of the hierarchical pore graphene material simultaneously has a micropore distribution peak and a mesopore distribution peak, the resistivity of the hierarchical pore graphene material is lower than 1100m omega cm, and the conductivity is good.
According to some embodiments of the present invention, in the step (1), the solution is formed in a manner not particularly limited, and for example, the solution may be formed by heating, and further preferably by heating with stirring. The temperature of heating and the rate of stirring are not particularly limited in the present invention, either, so long as the solution can be formed.
According to some embodiments of the present invention, preferably, in the step (1), the precursor material is obtained by dissolving a transition metal salt, an alkali metal salt and/or a base, and a carbon source in a solvent to form a solution, and then removing the solvent from the solution. In the present invention, the kind of the solvent is not particularly limited, and the solvent is preferably water and/or ethanol, more preferably water, so as to form a solution; the amount of the solvent used in the present invention is not particularly limited, and is also based on the ability to form a solution. The solvent in the solution can be removed by drying, and the temperature and process of drying can be known by those skilled in the art.
According to some embodiments of the present invention, preferably, in the step (1), the transition metal salt is one or more of organic acid salt, carbonate and basic carbonate of transition metal; more preferably an organic carboxylate salt of a transition metal.
According to some embodiments of the invention, preferably, the transition metal is a group viii metal, preferably at least one of iron, cobalt, nickel and copper, more preferably nickel.
According to a preferred embodiment of the present invention, the transition metal salt is selected from at least one of nickel acetate, cobalt acetate and basic nickel carbonate.
According to some embodiments of the present invention, in order to facilitate further control of the hierarchical pore structure of the graphene material, preferably, the alkali metal in the alkali metal-containing salt and/or the base is selected from at least one of Li, na, and K.
According to some embodiments of the present invention, preferably, the alkali metal-containing salt and/or base is selected from at least one of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, potassium sulfate, and sodium sulfate, more preferably at least one of potassium hydroxide, potassium carbonate, and sodium carbonate.
According to some embodiments of the present invention, in order to facilitate further regulation of the surface structure of the graphene material, preferably, the carbon source is selected from organic polyacids which do not contain nitrogen elements or contain nitrogen elements, further preferably, the carbon source is at least one of citric acid, maleic acid, isophthalic acid, terephthalic acid, ethylenediaminetetraacetic acid, urea, 2, 5-pyridinedicarboxylic acid, amino acids, and malic acid, and more preferably, at least one of citric acid, terephthalic acid, and ethylenediaminetetraacetic acid.
According to some embodiments of the present invention, in order to further achieve effective regulation of the carbon layer thickness and the hierarchical pore structure of the graphene material, it is preferable that the mass ratio of the carbon source, the alkali metal-containing salt and/or alkali, and the transition metal salt is 0.1 to 10:0.5-5:1, preferably 0.5 to 5:1-3:1, more preferably 0.8 to 3:1-3:1. the preferred embodiment is more beneficial to forming the hierarchical porous graphene material simultaneously containing the micropore structure and the mesopore structure.
In the present invention, too much alkali metal-containing salt and/or alkali may cause the obtained graphene material to form fragments, and too little alkali metal-containing salt and/or alkali may cause the graphene material to have a small microporous structure.
According to some embodiments of the present invention, preferably, in step (2), the pyrolysis temperature of the pyrolysis is 450 to 1300 ℃, preferably 600 to 1200 ℃. In the present invention, the pyrolysis temperature of the pyrolysis is preferably in the above range, which is advantageous for controlling the shape and graphitization degree of the graphene material.
According to some embodiments of the present invention, preferably, in step (2), the method for pyrolysis comprises: heating to pyrolysis temperature at a speed of 0.5-30 deg.C/min, and maintaining the temperature at the pyrolysis temperature for 20-600min; further preferably, the temperature is raised to the pyrolysis temperature at the speed of 1-10 ℃/min, and the constant temperature is kept at the pyrolysis temperature for 60-480min.
According to some embodiments of the present invention, preferably, the inert atmosphere is provided by at least one of nitrogen, argon, neon and helium, more preferably nitrogen and/or argon; and/or the presence of a gas in the atmosphere,
the reducing atmosphere is provided by hydrogen and optionally an inert gas, the inert gas being at least one of nitrogen, argon, neon and helium.
According to some embodiments of the present invention, preferably, in the step (3), the pyrolysis product is acid-washed with an aqueous solution of an inorganic acid and/or an organic acid, and specifically, the acid-washed pyrolysis product may be: the pyrolysis product is mixed with an aqueous solution of an inorganic acid and/or an organic acid, and the mixing method is not particularly limited in the present invention, and the mixing may be performed by using ultrasound or stirring. The acid wash serves to remove transition metals from the material.
According to some embodiments of the present invention, preferably, the aqueous solution of inorganic acid and/or organic acid is selected from one or more aqueous solutions of hydrochloric acid, sulfuric acid, nitric acid and citric acid, further preferably one or more aqueous solutions of hydrochloric acid, sulfuric acid and citric acid; preferably, the concentration of the aqueous solution of the inorganic acid and/or the organic acid is 0.1 to 10moL/L.
According to some embodiments of the invention, the aqueous solution of an inorganic or organic acid preferably has a pH of less than 7.
According to some embodiments of the present invention, preferably, in the step (3), the temperature of the acid washing is 20-120 ℃, preferably 60-90 ℃; the time is 0.1 to 48 hours, preferably 4 to 12 hours.
According to some embodiments of the present invention, in step (3), the solid-liquid separation method is not particularly limited, and may be performed by a solid-liquid separation method known in the art, for example, by filtration. Since the filtrate contains a transition metal capable of preparing a precursor, preferably, the filtrate obtained by the solid-liquid separation can be used as a raw material for preparing a precursor material, and specifically, the solvent in the filtrate is removed to obtain the precursor material.
According to some embodiments of the present invention, the washing is used to remove acid remaining on the graphene material during the acid washing process, and thus, various water washing methods capable of washing the graphene material to be neutral are suitable for the present invention.
According to some embodiments of the invention, the drying is used to remove water from the graphene material. The drying can be carried out under normal pressure or under reduced pressure. The conditions for drying may include: the temperature is 80-140 ℃ and the time is 2-12h.
According to some embodiments of the present invention, preferably, the transition metal salt, the alkali metal salt and/or the alkali, and the carbon source are used in amounts such that the molar content of carbon element in the prepared hierarchical porous graphene material is 90 to 98% and the molar content of oxygen element in the prepared hierarchical porous graphene material is 2 to 10% as determined by X-ray photoelectron spectroscopy;
more preferably, the transition metal salt, the alkali metal salt and/or the alkali and the carbon source are used in amounts such that the molar content of the carbon element and the molar content of the oxygen element in the prepared hierarchical porous graphene material are 91-97% and 3-8%, respectively, as measured by X-ray photoelectron spectroscopy.
According to some embodiments of the present invention, preferably, the transition metal salt, the alkali metal salt and/or the alkali, and the carbon source are used in amounts such that the prepared hierarchical porous graphene material has a nitrogen element content of 0.2 to 5% by mole as measured by X-ray photoelectron spectroscopy.
According to some embodiments of the present invention, the hierarchical porous graphene material may contain various doping elements known to those skilled in the art to be applicable to carbon materials, and preferably, the hierarchical porous graphene material does not contain iron, cobalt, nickel, copper, boron, phosphorus, fluorine, chlorine, bromine, iodine, sulfur, and other elements.
In a third aspect of the present invention, the application of the hierarchical porous graphene material described in the first aspect or the hierarchical porous graphene material prepared by the method described in the second aspect in a fuel cell catalyst carrier and/or a fuel cell catalyst is provided.
According to some embodiments of the present invention, the fuel cell catalyst may be prepared using a method for preparing a fuel cell catalyst that is well known in the art, and the present invention is not particularly limited thereto. Preferably, the method of preparing the fuel cell catalyst comprises:
(a) Dispersing a hierarchical porous graphene material in a solvent, and then adding a platinum compound into the solvent in which the hierarchical porous graphene material is dispersed to obtain a suspension;
(b) A reducing agent is contacted with the suspension.
According to some embodiments of the present invention, the solvent may be any solvent known in the art that can be used to prepare a fuel cell catalyst, and is preferably at least one of water, ethanol, and ethylene glycol. Preferably, the solvent is used in an amount of 50-1500mL per gram of the hierarchical porous graphene material.
According to some embodiments of the present invention, the platinum compound may be a platinum compound known in the art to be used for preparing a fuel cell catalyst, and may be at least one of chloroplatinic acid, chloroplatinate, platinum chloride, platinum nitrate, and a platinum complex, preferably chloroplatinic acid. Preferably, the molar ratio of the multi-level pore graphene material to the platinum compound calculated as platinum element is 10-70:1.
according to some embodiments of the present invention, the reducing agent may be a reducing agent known in the art, and may be at least one of formaldehyde, formic acid, sodium thiosulfate, sodium borohydride and potassium borohydride, and preferably formic acid. Preferably, the molar ratio of the reducing agent to the platinum compound in terms of platinum element is 2-10:1
According to some embodiments of the invention, preferably, the pH of the suspension is between 9 and 11.
According to some embodiments of the invention, preferably, the reducing agent is contacted with the suspension at a temperature of 30 to 90 ℃ for a time of 0.1 to 8h. Preferably, after the reducing agent is contacted with the suspension, the method further comprises the steps of filtering the mixture after reaction, washing and drying a filter cake obtained by filtering.
According to some embodiments of the present invention, preferably, the loading amount of Pt in the fuel cell catalyst may be 20 to 70wt% based on the total weight of the fuel cell catalyst.
The hierarchical porous graphene material provided by the invention contains a microporous structure and a mesoporous structure, has the resistivity lower than 1100m omega cm, and can be used as a carrier to be applied to a fuel cell catalyst. Since the present invention relates to only the improvement of the carrier, when the hierarchical porous graphene material of the present invention is applied to a fuel cell catalyst, there is no particular limitation on other compositions and structures of the fuel cell catalyst. When the Pt/C catalyst prepared from the hierarchical pore graphene material provided by the invention is applied to an oxidation reduction reaction, the half-wave potential is 0.83-0.871V, and the electrochemical activity area (ECSA) is 40-160m 2 g -1 -Pt, with better catalytic activity.
The present invention will be described in detail below by way of examples.
Unless otherwise specified, all reagents used in the invention are analytically pure, and all reagents are commercially available.
The morphology of the material is characterized by a high-resolution transmission electron microscope (HRTEM), the model of the adopted high-resolution transmission electron microscope is JEM-2100 (Japan Electron Co., ltd.), and the testing conditions of the high-resolution transmission electron microscope are as follows: the acceleration voltage was 200kV. The diameter of the material and the number of layers of the graphitized carbon layer were measured by high-resolution transmission electron microscopy (HRTEM).
The pore structure properties of the material were examined by the BET test method. Specifically, a Quantachrome AS-6B type analyzer is adopted for measurement, the specific surface area, the micropore area and the pore volume of the material are obtained by a Brunauer-Emmett-Taller (BET) method, a mesoporous distribution curve is obtained by calculating a desorption curve according to a Barrett-Joyner-Halenda (BJH) method, and a micropore pore diameter distribution curve is obtained by calculating an isothermal curve according to a Horvath-Kawazoe (HK) method.
The contents of elements on the surface of the material and the contents of various oxygen species were determined by X-ray photoelectron spectroscopy (XPS), which was tested on an ESCALab250 type X-ray photoelectron spectrometer equipped with Thermo Avantage V5.926 software, manufactured by Thermo Scientific, with an excitation source of monochromated Al K.alpha.X-rays, an energy of 1486.6eV, a power of 150W, a transmission energy for narrow scanning of 30eV, and a base vacuum of 6.53X 10 during analytical testing - 9 mbar, electron binding energy was corrected with the C1s peak (284.6 eV) of elemental carbon, data processed on Thermo Avantage software, and quantitative analysis was performed in the analysis module using the sensitivity factor method. The materials were dried at a temperature of 150 c and 1 atm under a helium atmosphere for 3 hours before testing.
The resistivity of the material is measured according to the method for measuring the resistivity of the carbon raw material and coke in the national standard GB/T2459-018, and the used instrument is an ST-2722 type semiconductor powder resistivity tester produced by Suzhou crystal lattice electronics.
The degree of graphitization of the material was characterized by Raman (Raman) spectroscopy at 1355cm -1 The peak (D peak) is attributed to structural defect and is amorphous carbon, 1585cm -1 The peak (G peak) is assigned to carbon in a planar structure. Is usually used with I D /I G (intensity ratio of the D peak to the G peak) to characterize the degree of graphitization of the material. I.C. A D /I G The higher the number of defects, the lower the degree of graphitization. The Raman spectrum of the material is obtained by using an RM2000 type micro confocal Raman spectrometer (product of Reinhaw company), and the technical indexes are as follows: the excitation source is He-Ne laser with wavelength of 525 nm.
The electrochemical performance test of the Pt/C catalyst is determined according to the test method of the electrocatalyst of the GB/T20042.4-2009 proton exchange membrane fuel cell.
Examples 1 to 8 are provided to illustrate a hierarchical porous graphene material and a method for preparing the same.
Example 1
(1) Weighing 10g of nickel acetate, 20g of citric acid and 10g of potassium hydroxide, adding into a beaker containing 50mL of deionized water, stirring for dissolving, and heating to evaporate water to obtain a precursor material.
(2) And (2) placing the precursor material obtained in the step (1) in a porcelain boat, then placing the porcelain boat in a constant temperature area of a tube furnace, introducing nitrogen with the flow of 100mL/min, heating to 450 ℃ at the speed of 15 ℃/min, keeping the temperature for 4h, stopping heating, and cooling to room temperature under the nitrogen atmosphere to obtain a pyrolysis product.
(3) And (3) adding the pyrolysis product obtained in the step (2) into 200mL of 2M hydrochloric acid aqueous solution, stirring for 8h at 80 ℃, filtering, washing, and drying the obtained solid for 4h in a constant-temperature oven at 120 ℃ to obtain the hierarchical-pore graphene material.
FIG. 1 is a pore volume-pore size distribution curve of the material, and it can be seen that the material has a mesopore distribution peak at 3.85nm and three micropore distribution peaks at 0.43nm, 0.52nm and 0.63 nm.
The surface composition, specific surface area, micropore area, total pore volume, I of the material D /I G And the resistivity are listed in table 1.
FIG. 2 is a TEM image of the material, and it can be seen that the material is formed by stacking a plurality of hollow nano carbon cages together in a staggered manner, each unit is formed by interweaving 4-10 carbon layers together, and obvious graphite carbon lattice stripes can be seen, which indicates that the material is a cage graphene material. The diameter of the material is 5-50nm.
Figure 3 is an XPS plot of the material,as can be seen from the figure, two elements of carbon and oxygen exist in the material, according to the ratio of calculated peak areas, the molar content of the carbon in the multi-level pore graphene material is 93.16%, and the molar content of the oxygen is 6.84%, and the content of the oxygen determined by the spectral peak corresponding to the C-O group in the material can be calculated by XPS peak splitting software
The molar ratio of the oxygen content determined by the peaks of the radicals is given in table 1.
Example 2
(1) Weighing 10g of nickel acetate, 20g of citric acid and 10g of potassium hydroxide, adding the nickel acetate, the citric acid and the potassium hydroxide into a beaker containing 50mL of deionized water, stirring and dissolving, and heating to evaporate water to obtain a precursor material.
(2) And (2) placing the precursor material obtained in the step (1) in a porcelain boat, then placing the porcelain boat in a constant temperature area of a tube furnace, introducing nitrogen with the flow of 100mL/min, heating to 650 ℃ at the speed of 5 ℃/min, keeping the temperature for 2h, stopping heating, and cooling to room temperature under the nitrogen atmosphere to obtain a pyrolysis product.
(3) And (3) adding the pyrolysis product obtained in the step (2) into 200mL of aqueous solution containing 20g of citric acid, stirring for 8h at 100 ℃, filtering, washing a filter cake obtained by filtering with deionized water until the filtrate is neutral, collecting the filtrate, and drying the obtained solid in a constant-temperature oven at 120 ℃ for 4h to obtain the hierarchical-pore graphene material.
The pore volume-pore diameter distribution curve of the material has a mesopore distribution peak at the position of 3.89nm and a micropore distribution peak at the position of 0.45 nm.
The surface composition, specific surface area, micropore area, total pore volume, I of the material D /I G And the resistivity are listed in table 1.
A TEM image of the material is shown in fig. 4, from which it can be seen that the material is stacked by a plurality of nano carbon cages, and the material can be seen to have graphitized stripes, which indicates that the material is a graphitized cage graphene material having 2-10 carbon layers. The diameter of the material is 5-50nm.
An XPS analysis test is carried out on the material to obtain an XPS graph of the material, as shown in FIG. 5, as can be seen from the graph, two elements of a carbon element and an oxygen element exist in the material, according to the proportion of the calculated peak area, the molar content of the carbon element in the hierarchical porous graphene material is 94.76%, the molar content of the oxygen element is 5.24%, and the content of the oxygen element determined by the spectrum peak corresponding to the C-O group of the material can be calculated by XPS peak splitting software
The peak of the radical spectrum determined the molar ratio of the oxygen content to 1.08 (see table 1).
Example 3
(1) Weighing 10g of nickel acetate, 10g of citric acid and 10g of potassium hydroxide, adding into a beaker containing 50mL of deionized water, stirring for dissolving, and heating to evaporate water to obtain a precursor material.
(2) And (2) placing the precursor material obtained in the step (1) in a porcelain boat, then placing the porcelain boat in a constant temperature area of a tube furnace, introducing nitrogen with the flow of 100mL/min, heating to 900 ℃ at the speed of 25 ℃/min, keeping the temperature for 2h, stopping heating, and cooling to room temperature under the nitrogen atmosphere to obtain a pyrolysis product.
(3) And (3.0 g) of the pyrolysis product obtained in the step (2) is added into 100mL of 2M sulfuric acid aqueous solution, stirred for 4 hours at 80 ℃, filtered, washed, and the obtained solid is dried for 12 hours in a constant-temperature oven at 80 ℃ to obtain the hierarchical-pore graphene material.
The pore volume-pore diameter distribution curve of the material has two mesopore distribution peaks at 2.35nm and 3.77nm, and has one micropore distribution peak at 0.61 nm.
The surface composition, specific surface area, micropore area, total pore volume and I of the material D /I G And the resistivity are listed in table 1.
FIG. 6 is a TEM image of the material, and it can be seen that the material has a hollow cage structure, and 2-5 carbon layers are interwoven to form a cage. The diameter of the material is 10-50nm.
XPS analysis and test of the material can find thatThe molar contents of the carbon element and the oxygen element in the multi-level pore graphene material can be obtained according to the ratio of the calculated peak areas, and the content of the oxygen element determined by the spectral peak corresponding to the C-O group in the material can be calculated by XPS peak splitting software
The peaks of the radicals define the molar ratio of the oxygen content and the results are given in table 1.
Example 4
(1) Weighing 10g of nickel acetate, 30g of citric acid and 10g of potassium hydroxide, adding the nickel acetate, the citric acid and the potassium hydroxide into a beaker containing 50mL of deionized water, stirring and dissolving, and heating to evaporate water to obtain a precursor material.
(2) And (2) placing the precursor material obtained in the step (1) in a porcelain boat, then placing the porcelain boat in a constant temperature area of a tube furnace, introducing nitrogen with the flow of 100mL/min, heating to 1000 ℃ at the speed of 55 ℃/min, keeping the temperature for 1h, stopping heating, and cooling to room temperature under the nitrogen atmosphere to obtain a pyrolysis product.
(3) And (3.0 g) of the pyrolysis product obtained in the step (2) is added into 200mL of aqueous solution containing 30g of citric acid, the mixture is stirred for 4 hours at 100 ℃, filtered and washed, and the obtained solid is dried for 2 hours in a constant-temperature oven at 140 ℃ to obtain the hierarchical porous graphene material.
The pore volume-pore diameter distribution curve of the material has a mesopore distribution peak at 4.01nm and a micropore distribution peak at 0.61 nm.
The surface composition, specific surface area, micropore area, total pore volume and I of the material D /I G And the resistivity are listed in table 1.
FIG. 7 is a TEM image of the material, which is a hollow cage-like nanocarbon material, and 3-8 layers of carbon are interlaced to form a cage shape. The diameter of the material is 5-50nm.
XPS analysis and test on the material can show that the material contains two elements of carbon and oxygen, and the carbon and oxygen in the hierarchical pore graphene material can be obtained according to the ratio of the calculated peak areaAnd the content of oxygen element determined by the spectral peak corresponding to the C-O group in the material can be calculated by XPS peak separation software
The peaks of the radicals define the molar ratio of the oxygen content and the results are given in table 1.
Example 5
(1) Weighing 10g of cobalt acetate, 30g of terephthalic acid and 18.9g of sodium carbonate, adding the cobalt acetate, the terephthalic acid and the sodium carbonate into a beaker containing 50mL of deionized water, stirring and dissolving, and heating to evaporate water to obtain a precursor material.
(2) And (2) placing the solid obtained in the step (1) in a porcelain boat, then placing the porcelain boat in a constant temperature area of a tube furnace, introducing nitrogen with the flow of 50mL/min, heating to 650 ℃ at the speed of 5 ℃/min, keeping the temperature for 2h, stopping heating, and cooling to room temperature under the nitrogen atmosphere to obtain a pyrolysis product.
(3) And (3.0 g) of the pyrolysis product obtained in the step (2) is added into 200mL of hydrochloric acid aqueous solution of 2M, the mixture is stirred for 12 hours at the temperature of 80 ℃, filtered and washed, and the obtained solid is dried for 2 hours in a constant-temperature oven at the temperature of 120 ℃ to obtain the hierarchical-pore graphene material.
The pore volume-pore diameter distribution curve of the material has a mesopore distribution peak at the position of 3.77nm and a micropore distribution peak at the position of 0.62 nm.
The surface composition, specific surface area, micropore area, total pore volume and I of the material D /I G And the resistivity are listed in table 1.
FIG. 8 is a TEM image of the material, and it can be seen that the material is a hollow cage-like nanocarbon material formed by interweaving 2-10 layers of carbon. The diameter of the material is 5-50nm.
According to XPS analysis test of the material, the material has two elements of carbon and oxygen, the molar contents of the carbon and the oxygen in the multi-level pore graphene material can be obtained according to the ratio of the calculated peak areas, and the content of the oxygen determined by the spectral peak corresponding to the C-O group in the material can be calculated by XPS peak splitting software
The peaks of the radicals define the molar ratio of the oxygen content and the results are given in table 1.
Example 6
(1) Weighing 10g of basic nickel carbonate, 20g of citric acid and 30g of potassium carbonate, adding the basic nickel carbonate, the citric acid and the potassium carbonate into a beaker containing 50mL of deionized water, stirring and dissolving, and heating to evaporate water to obtain a precursor material.
(2) And (2) placing the precursor material obtained in the step (1) in a porcelain boat, then placing the porcelain boat in a constant temperature area of a tube furnace, introducing nitrogen with the flow rate of 150mL/min, heating to 650 ℃ at the speed of 10 ℃/min, keeping the temperature for 2h, stopping heating, and cooling to room temperature under the nitrogen atmosphere to obtain a pyrolysis product.
(3) Adding the pyrolysis product obtained in the step (2) into 200mL 1M hydrochloric acid aqueous solution, stirring for 12h at 100 ℃, filtering, collecting filtrate, washing a filter cake obtained by filtering with deionized water until the filtrate is neutral, and drying the obtained solid in a constant-temperature oven at 120 ℃ for 4h to obtain the hierarchical-pore graphene material.
The pore volume-pore diameter distribution curve of the material has two mesopore distribution peaks at 3.97nm and 40nm, and has one micropore distribution peak at 0.62 nm.
The surface composition, specific surface area, micropore area, total pore volume and I of the material D /I G And the resistivity are listed in table 1.
FIG. 9 is a TEM image of the material, and it can be seen that the material is a hollow cage-like nanocarbon material composed of 2-10 layers of carbon. The diameter of the material is 5-50nm.
According to XPS analysis test of the material, the material has two elements of carbon and oxygen, the molar contents of the carbon and the oxygen in the multi-level pore graphene material can be obtained according to the ratio of the calculated peak areas, and the content of the oxygen determined by the spectral peak corresponding to the C-O group in the material can be calculated by XPS peak splitting software
The peaks of the radicals define the molar ratio of the oxygen content and the results are given in table 1.
Example 7
Directly evaporating the water content of the filtrate collected in the embodiment 2 to dryness to obtain a solid serving as a precursor material of a pyrolysis product, roasting the precursor material at 900 ℃ for 2 hours under the protection of inert gas argon to obtain the pyrolysis product, and obtaining the hierarchical porous graphene material by the same steps as the embodiment 2.
The pore volume-pore diameter distribution curve of the material has a mesopore distribution peak at 3.84nm and a micropore distribution peak at 0.61 nm.
The surface composition, specific surface area, micropore area, total pore volume and I of the material D /I G And the resistivity are listed in table 1.
Fig. 10 is a TEM image of the material, which is seen to have a hollow cage structure consisting of 2 to 7 layers of carbon, with lattice fringes of graphitized carbon. The diameter of the material is 10-50nm.
XPS analysis tests on the material show that the material contains two elements of carbon and oxygen, the molar contents of the carbon and the oxygen in the multi-level pore graphene material can be obtained according to the ratio of peak areas calculated, and XPS peak separation software can calculate the content of the oxygen determined by a spectrum peak corresponding to a C-O group and the content of the oxygen determined by a spectrum peak corresponding to a C-O group in the material
The peaks of the radicals define the molar ratio of the oxygen content and the results are given in table 1.
Example 8
(1) Weighing 15g of basic nickel carbonate, 20.9g of ethylenediamine tetraacetic acid and 5.72g of potassium hydroxide, adding the materials into a beaker containing 50mL of deionized water, stirring the materials to dissolve the materials, and heating the materials to evaporate water to obtain a precursor material.
(2) And (2) placing the precursor material obtained in the step (1) in a porcelain boat, then placing the porcelain boat in a constant temperature area of a tube furnace, introducing nitrogen with the flow of 70mL/min, heating to 650 ℃ at the speed of 10 ℃/min, keeping the temperature for 2h, stopping heating, and cooling to room temperature under the nitrogen atmosphere to obtain a pyrolysis product.
(3) And (3) adding the pyrolysis product obtained in the step (2) into 200mL 1M hydrochloric acid aqueous solution, stirring for 12h at 100 ℃, filtering, collecting filtrate, washing with deionized water until the filtrate is neutral, and drying the obtained solid in a constant-temperature oven at 120 ℃ for 4h to obtain the hierarchical-pore graphene material.
The pore volume-pore diameter distribution curve of the material has two mesopore distribution peaks at 2.4nm and 3.97nm, and has one micropore distribution peak at 0.62 nm.
The surface composition, specific surface area, micropore area, total pore volume and I of the material D /I G And the resistivity are listed in table 1.
Fig. 11 is a TEM image of the material, which is seen to have a hollow cage structure consisting of 3 to 7 layers of carbon, and which is seen to have lattice fringes of graphitized carbon in the TEM image. The diameter of the material is 5-30nm.
XPS analysis tests on the material show that the material contains three elements of carbon, oxygen and nitrogen, the molar contents of the carbon, the oxygen and the nitrogen in the multi-level pore graphene material can be obtained according to the proportion of the calculated peak area, and XPS peak separation software can calculate the content of the oxygen determined by the spectral peak corresponding to the C-O group and the content of the oxygen determined by the spectral peak corresponding to the C-O group in the material
The peaks of the radicals define the molar ratio of the oxygen content and the results are given in table 1.
Comparative example 1
A carbon material was obtained by following the procedure of example 2 except that potassium hydroxide was not added in the step (1) and the remaining raw materials, steps, conditions and the like were the same.
Two mesopore distribution peaks exist only at 4.23nm and 11.23nm on the pore volume-pore diameter distribution curve of the material, and no micropore distribution peak exists.
The surface composition, specific surface area, total pore volume and I of the material D /I G And the resistivity are listed in table 1.
Fig. 12 is a TEM image of the material, and it can be seen from the figure that although the material has a carbon cage structure, a large amount of metal particles exist in the material, and the purity is low.
When the material is subjected to XPS analysis test, 1.81 percent of nickel element is also present in the material besides carbon element and oxygen element. The content of oxygen element in the material determined by the peak corresponding to C-O group and the content of oxygen element determined by the peak corresponding to C-O group can be calculated by XPS peak separation software
The peaks of the radicals define the molar ratio of the oxygen content and the results are given in table 1.
TABLE 1
Note: in the table, n (C-O)/n (O-C = O) is the content of oxygen element in the material determined by the peak corresponding to the C-O group and the content of oxygen element determined by the peak corresponding to the C-O group
The molar ratio of the content of the oxygen element is determined by the spectrum peak of the radical.
Test example
This test example is used to illustrate a fuel cell catalyst and a method for preparing the same.
Preparation of Pt/C catalyst: respectively dispersing 0.6g of the hierarchical porous graphene material obtained in examples 1-8 in 200mL of deionized water, adding a certain amount of chloroplatinic acid, performing ultrasonic dispersion to form a suspension, and then adding a sodium carbonate aqueous solution to adjust the pH of the suspension to 11; heating the suspension to 80 ℃, adding formic acid under stirring to carry out reduction reaction, wherein the molar ratio of the reducing agent to chloroplatinic acid calculated by platinum element is 5:1, maintaining the reaction for 8 hours; and filtering the mixture after reaction, washing until the pH value of the solution is neutral, and drying at 100 ℃ to obtain the Pt/C catalysts A1-A8 with the Pt loading of 32 wt%.
Catalytic performance testing of Pt/C catalysts: the electrochemical properties of the prepared Pt/C catalysts A1 to A8 were measured in a 0.1M perchloric acid atmosphere, respectively, and the results are shown in Table 2.
Comparative test example
Preparation of Pt/C catalyst: dispersing 0.6g of the carbon material obtained in the comparative example 1 in 200mL of deionized water, adding a certain amount of chloroplatinic acid, performing ultrasonic dispersion to form a suspension, and then adding a sodium carbonate aqueous solution to adjust the pH of the suspension to 11; heating the suspension to 80 ℃, adding formic acid under stirring to carry out reduction reaction, wherein the molar ratio of the reducing agent to chloroplatinic acid calculated by platinum element is 5:1, maintaining the reaction for 8 hours; and filtering the reacted mixture, washing until the pH value of the solution is neutral, and drying at 100 ℃ to obtain the Pt/C catalyst D1 with the Pt loading of 32 wt%.
The prepared Pt/C catalyst D1 was subjected to electrochemical measurements in a 0.1M perchloric acid atmosphere according to the method of test example, and the results are shown in Table 2.
TABLE 2
From the data, the pore diameter distribution curve of the hierarchical pore graphene material provided by the invention has a micropore distribution peak and a mesopore distribution peak at the same time, has a hierarchical pore structure, and has low resistivity, the resistivity is lower than 1100m omega cm, and the conductivity is good. The hierarchical porous graphene material provided by the invention is suitable for being used as an adsorption material, a catalyst carrier and an electro-catalysis and energy storage material.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A multi-level pore graphene material has a micropore distribution peak and a mesopore distribution peak in a pore size distribution curve, and the resistivity of the graphene material is lower than 1100m omega cm.
2. The multi-level pore graphene material according to claim 1, wherein the graphene material has a pore size distribution curve in which at least one mesopore distribution peak exists at 2-50nm, preferably two mesopore distribution peaks exist at 2.3-4nm and 3.5-40 nm; and/or
In the pore size distribution curve of the graphene material, at least one micropore distribution peak exists at a position of 0.4-1 nm; and/or
In the pore size distribution curve of the graphene material, two micropore distribution peaks exist at 0.4-0.6nm and 0.5-0.8 nm.
3. The multi-level pore graphene material according to claim 1, wherein the graphene material has a resistivity of 50-1000m Ω -cm, preferably 60-600m Ω -cm.
4. The hierarchical porous graphene material according to any one of claims 1 to 3, wherein the graphene material has a diameter of 2 to 100nm, preferably 5 to 50nm; and/or
The specific surface area of the graphene material is 100-1500m 2 A/g, preferably from 300 to 1500m 2 G, micropore area of 2-1000m 2 A/g, preferably of from 100 to 800m 2 (ii)/g, total pore volume of 0.3-1.5cm 3 In terms of/g, preferably from 0.4 to 1.2cm 3 /g。
5. The multigraded pore graphene material according to any one of claims 1 to 4, wherein the graphene material has a molar content of carbon element of 90 to 98%, preferably 91 to 97%, as determined by X-ray photoelectron spectroscopy; and/or the molar content of the oxygen element of the graphene material is 2-10%, preferably 3-8% by X-ray photoelectron spectroscopy; and/or
In the X-ray photoelectron spectrum of the graphene material, the content of oxygen element determined by a spectrum peak corresponding to a CO group and the content of oxygen element determined by a spectrum peak corresponding to a CO group
The molar ratio of the content of oxygen element determined by the peak of the group is 0.6-5:1, preferably 0.8 to 3:1; and/or
In the Raman curve of the graphene material, I D /I G In the range of 0.1 to 1.2, preferably 0.17 to 1.
6. A preparation method of a hierarchical porous graphene material comprises the following steps:
(1) Providing a solution containing a transition metal salt, a salt containing an alkali metal and/or an alkali and a carbon source, and then drying to obtain a precursor material;
(2) Pyrolyzing the precursor material obtained in the step (1) in an inert atmosphere or a reducing atmosphere to obtain a pyrolysis product;
(3) And (3) carrying out acid washing on the pyrolysis product, and then carrying out solid-liquid separation and drying.
7. The production method according to claim 6, wherein in the step (1), the transition metal is a group VIII metal, preferably at least one of iron, cobalt, nickel and copper, more preferably nickel; and/or
The transition metal salt is one or more of organic acid salt, carbonate and basic carbonate of transition metal, and is preferably organic carboxylate of transition metal; and/or
The alkali metal is at least one selected from Li, na and K; and/or
The alkali metal-containing salt and/or alkali is selected from at least one of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, potassium sulfate and sodium sulfate, and more preferably at least one of potassium hydroxide, potassium carbonate and sodium carbonate; and/or
The carbon source is selected from organic polybasic acid, preferably at least one of citric acid, maleic acid, isophthalic acid, terephthalic acid, ethylene diamine tetraacetic acid, urea, 2, 5-pyridinedicarboxylic acid, amino acid and malic acid, and more preferably at least one of citric acid, terephthalic acid and ethylene diamine tetraacetic acid;
and/or the mass ratio of the carbon source, the salt containing alkali metal and/or alkali and the transition metal salt is 0.1-10:0.5-5:1, preferably 0.5 to 5:1-3:1, more preferably 0.8 to 3:1-3:1; and/or
The solvent in the solution is water and/or ethanol, preferably water.
8. The production method according to claim 6, wherein in the step (2), the pyrolysis temperature of the pyrolysis is 450 to 1300 ℃, preferably 600 to 1200 ℃; and/or
The method of pyrolysis comprises: heating to pyrolysis temperature at a speed of 0.5-30 deg.C/min, and maintaining the temperature at the pyrolysis temperature for 20-600min; preferably, the temperature is raised to the pyrolysis temperature at the speed of 1-10 ℃/min, and the constant temperature is kept at the pyrolysis temperature for 60-480min; and/or
The inert atmosphere is provided by at least one of nitrogen, argon, neon and helium; and/or
The reducing atmosphere is provided by hydrogen and optionally an inert gas.
9. The production method according to any one of claims 6 to 8, wherein, in step (3), the pyrolysis product is subjected to acid washing with an aqueous solution of an inorganic acid and/or an aqueous solution of an organic acid; and/or
The inorganic acid aqueous solution and/or the organic acid aqueous solution is/are one or more aqueous solutions of hydrochloric acid, sulfuric acid, nitric acid and citric acid, and is/are preferably hydrochloric acid aqueous solution; and/or
The pH value of the inorganic acid aqueous solution or the organic acid aqueous solution is less than 7; and/or
The pickling temperature is 20-120 ℃, and preferably 60-90 ℃; the time is 0.1 to 48 hours, preferably 4 to 12 hours.
10. Use of the multigraded pore graphene material according to any one of claims 1 to 5 or prepared according to the method of any one of claims 6 to 9 in a fuel cell catalyst support and/or a fuel cell catalyst.
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