CN113937309B - Monoatomic catalyst and preparation method thereof - Google Patents

Monoatomic catalyst and preparation method thereof Download PDF

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CN113937309B
CN113937309B CN202111247275.1A CN202111247275A CN113937309B CN 113937309 B CN113937309 B CN 113937309B CN 202111247275 A CN202111247275 A CN 202111247275A CN 113937309 B CN113937309 B CN 113937309B
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CN113937309A (en
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张海宁
范美玲
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Wuhan University of Technology WUT
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9041—Metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9091—Unsupported catalytic particles; loose particulate catalytic materials, e.g. in fluidised state
    • 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
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Abstract

The invention discloses a single-atom catalyst and a preparation method thereof, and belongs to the technical field of catalysts. The book is provided withThe invention provides a preparation method of a single-atom catalyst, which comprises the following steps: coating g-C with metal foil 3 N 4 And (3) heating the polyacrylonitrile fiber to 900-1100 ℃ in an inert gas atmosphere, and preserving heat to obtain the monoatomic catalyst. The invention also comprises the monoatomic catalyst prepared by the preparation method. The preparation method provided by the invention does not need to use metal complex precursors and further acid washing, and avoids using organic solvents, and the half-wave potential of the prepared single-atom catalyst is as high as 0.83V.

Description

Monoatomic catalyst and preparation method thereof
Technical Field
The invention relates to the technical field of catalysts, in particular to a single-atom catalyst and a preparation method thereof.
Background
The oxyhydrogen fuel cell is a novel clean energy conversion device for directly converting chemical energy into electric energy, has high energy conversion efficiency, is environment-friendly and pollution-free, and is focused by more and more scientific researchers in recent years. However, the low oxygen reduction efficiency of the cathode of the hydrogen-oxygen fuel cell limits its rapid development, so the development of a highly efficient oxygen reduction catalyst is of great importance. The existing catalysts applied to hydrogen-oxygen fuel cell cathodes are mostly noble metal platinum nano particles or platinum alloys, and have good catalytic effects, but the noble metal platinum catalysts are expensive, limited in earth storage capacity, and limited in large-scale application due to poor stability and methanol tolerance. Therefore, developing a low-cost and efficient oxygen reduction reaction catalyst is an important means for accelerating commercialization of hydrogen-oxygen fuel cells.
In addition to noble metal platinum and its alloy compounds, transition metals (such as copper, iron, cobalt, nickel) and their compounds are based on their excellent oxygen reduction catalytic performance, so that low cost and rich earth storage are also of great concern, and the research on transition metal oxides, transition metal nanoparticles and their alloys is mainly focused at present. Based on the excellent catalytic performance of the noble metal platinum catalyst for the oxygen reduction reaction, the research on the noble metal platinum catalyst is mainly focused on improving the utilization rate and stability of the catalyst and reducing the use amount of the noble metal platinum so as to achieve the effect of reducing the use cost on the premise of not sacrificing the performance; meanwhile, the metal nano particles are agglomerated to different degrees in the high-temperature pyrolysis process of the transition metal, so that the concentration of active sites is reduced, and the catalytic efficiency of the catalyst is greatly reduced. Therefore, the search for oxygen reduction catalysts with high dispersion to increase the catalyst utilization is an effective method for solving the problems of the current oxygen reduction catalysts.
A single-atom catalyst is a highly efficient catalyst in which a metal is supported on a carrier in the form of a single atom. Because of the characteristic that each metal atom is singly dispersed on the carrier, the single-atom catalyst has the characteristics of uniform and stable property and extremely high selectivity; in addition, since the active sites are completely exposed, the catalytic efficiency can be maximized. These advantages can effectively solve the problems of high cost of noble metals and agglomeration of transition metal nanoparticles. Moreover, in addition to developing high performance, low cost oxygen reduction catalysts, it is also important to investigate the mechanism of the oxygen reduction reaction. The transition metal-based catalyst is often an aggregate integrating multiple active sites such as metal nano particles, metal nitrides, metal carbides and the like, so the mechanism of the catalytic oxygen reduction reaction of the transition metal-based catalyst has not been defined. Single-atom catalysts have single catalytic active sites, and are effective means for exploring the mechanism of the oxygen reduction reaction of transition metals in comparison with single catalytic environments. At present, the common synthesis method of the single-atom catalyst is mainly to synthesize a transition metal complex firstly or use a metal organic framework structure as a template and the like, and then obtain a monodisperse metal catalyst through further carbonization treatment; or the monoatomic catalyst is obtained by high-temperature heat treatment of a transition metal-containing precursor and subsequent removal of metal nanoparticles by acid washing. These methods are not only relatively cumbersome to handle, but also use large amounts of organic solvents during the synthesis, and subsequent waste recovery is relatively complex and not environmentally friendly.
Disclosure of Invention
The invention aims to overcome the technical defects, and provides a single-atom catalyst and a preparation method thereof, which solve the technical problems of how to avoid using an organic solvent and an acid washing step to prepare the single-atom catalyst with high half-wave potential in the prior art.
In order to achieve the technical purpose, the technical scheme of the invention provides a preparation method of a single-atom catalyst, which comprises the following steps: coating g-C with metal foil 3 N 4 A polyacrylonitrile fiber, a fiber having a high molecular weight,and in an inert gas atmosphere, heating to 900-1100 ℃ and preserving heat to obtain the monoatomic catalyst.
Further, the heating rate is 2-8 ℃/min.
Further, the time of heat preservation is 0.5-3h.
Further, the metal foil is copper foil, iron foil or nickel foil.
Further, the g-C 3 N 4 The polyacrylonitrile fiber is prepared by the following steps:
will g-C 3 N 4 Mixing the nanosheet mother solution and the polyacrylonitrile mother solution to obtain a spinning solution, and then adopting an electrostatic spinning method by taking the spinning solution as a raw material to prepare the g-C 3 N 4 Polyacrylonitrile fiber.
Further, the g-C 3 N 4 Nanosheet mother liquor and polyacrylonitrile mother liquor according to g-C 3 N 4 And mixing the nanosheets and the polyacrylonitrile in a mass ratio of 1:1-3 to obtain the spinning solution.
Further, the g-C 3 N 4 g-C in nanosheet mother liquor 3 N 4 The nano-sheet is prepared by the following steps: one or more of urea, dicyandiamide and melamine are used as raw materials, and the catalyst is prepared by calcining at 500-600 ℃ under the protection of inert gas.
Further, the calcination time is 3-4 hours.
Further, the g-C 3 N 4 The polyacrylonitrile fiber is placed in a porcelain boat, and the top of the porcelain boat is coated by the metal foil.
In addition, the invention also provides a single-atom catalyst, which is prepared by the preparation method of the single-atom catalyst.
Compared with the prior art, the invention has the beneficial effects that: g-C 3 N 4 Polyacrylonitrile fiber is a porous material, metal atoms are separated from the binding of adjacent metal atoms by nitrogen-doped carbon nanofibers and captured by utilizing the metal foil along with the breakage of metal bonds at the high temperature of 900-1100 ℃, and the metal atoms are coordinated with nitrogen, so that the polyacrylonitrile fiber is anchored in an aza-carbon nano network in a single atom modeThe single-atom catalyst prepared by the method does not need further acid washing, avoids using an organic solvent and a transition metal complex, and has a half-wave potential of up to 0.83V.
Drawings
FIG. 1 is a graph showing the result of electrospinning in example 1 of the present invention 3 N 4 Polyacrylonitrile fiber precursor scanning electron microscopy.
FIG. 2 is a scanning electron microscope image of a single-atom catalyst prepared in example 1 of the present invention.
FIG. 3 is a transmission electron microscope image of a single-atom catalyst prepared in example 1 of the present invention.
FIG. 4 is a diagram of a single-atom catalyst spherical aberration transmission electron microscope (SEM) prepared in example 1 of the present invention.
FIG. 5 is a graph of the performance of the single-atom catalyst prepared in example 1 of the present invention and a commercial Pt/C catalyst in catalyzing an oxygen reduction reaction under alkaline conditions.
Detailed Description
The specific embodiment provides a preparation method of a single-atom catalyst, which comprises the following steps: coating g-C with metal foil 3 N 4 Heating the polyacrylonitrile fiber to 900-1100 ℃ according to the heating rate of 2-8 ℃/min in an inert gas atmosphere, and preserving the temperature for 0.5-3 hours to obtain the monoatomic catalyst; further, the metal foil is copper foil, iron foil or nickel foil; further, the g-C 3 N 4 The polyacrylonitrile fiber is placed in a porcelain boat, and the top of the porcelain boat is coated by the metal foil.
Further, the g-C 3 N 4 The polyacrylonitrile fiber is prepared by the following steps:
calcining one or more of urea, dicyandiamide and melamine at 500-600 ℃ under the protection of inert gas for 3-4 hours to obtain massive graphite-like carbon nitride, fully grinding the massive graphite-like carbon nitride, adding the massive graphite-like carbon nitride into deionized water, standing after ultrasonic treatment for a period of time, taking supernatant fluid for centrifugation, drying the centrifuged sediment under vacuum condition, and grinding to obtain g-C 3 N 4 Nanometer sheet, g-C 3 N 4 NanosheetsDispersing in N, N' -Dimethylformamide (DMF) to obtain g-C 3 N 4 A nanosheet dispersion;
adding polyacrylonitrile into anhydrous DMF solution, and stirring at a certain temperature to obtain yellow-brown transparent polyacrylonitrile mother liquor;
will g-C 3 N 4 Nanosheet mother liquor and polyacrylonitrile mother liquor according to g-C 3 N 4 Mixing the nano sheets and polyacrylonitrile in a mass ratio of 1:1-3 to obtain a spinning solution, wherein the mass fraction of the spinning solution is 9% -12%, and then preparing the g-C by taking the spinning solution as a raw material through an electrostatic spinning method 3 N 4 Polyacrylonitrile fiber.
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The following alkaline conditions for testing the half-wave potential were tested under alkaline conditions provided by 0.1mol/L potassium hydroxide.
Example 1
This example proposes a monoatomic catalyst prepared by the steps of:
calcining 10g melamine as a raw material for 4 hours at 550 ℃ under the protection of argon to obtain massive graphite-like carbon nitride, fully grinding 5g massive graphite-like carbon nitride, adding into 200mL deionized water, standing for 1 hour after ultrasonic treatment for 40min, taking supernatant, centrifuging at a rotation speed of 5000rpm, drying the centrifuged precipitate under vacuum condition, and grinding to obtain g-C 3 N 4 Nanometer sheet, 1.7 g-C 3 N 4 Dispersing the nanosheets in 50mL of N, N' -Dimethylformamide (DMF) to obtain g-C 3 N 4 A nanosheet dispersion;
adding 5g of Polyacrylonitrile (PAN) into an anhydrous DMF solution, and stirring for 24 hours at 60 ℃ to obtain 29.4g of yellow-brown transparent polyacrylonitrile mother liquor, wherein the mass fraction of the polyacrylonitrile is 17%;
will g-C 3 N 4 Nanosheet mother liquor and polyacrylonitrile mother liquor according to g-C 3 N 4 Mixing the nanosheets and polyacrylonitrile in a mass ratio of 1:1 to obtain a spinning solution, and then adopting the spinning solution as a raw material to prepare the g-C by adopting an electrostatic spinning method 3 N 4 Polyacrylonitrile fiber; specifically, selecting a needle with an inner diameter of 22 gauge, controlling the extrusion speed and the spinning voltage to be 0.1mm/min and 15KV respectively, and spinning to obtain g-C, wherein the distance between the needle and a receiving plate is 18cm 3 N 4 Polyacrylonitrile fiber; FIG. 1 is g-C 3 N 4 Scanning electron microscope image of polyacrylonitrile fiber, from which g-C is evident 3 N 4 The polyacrylonitrile fiber has a fibrous structure with a diameter of 300-500 nm.
The g-C 3 N 4 And (3) placing the polyacrylonitrile fibers in a porcelain boat, coating the top of the porcelain boat with a metal copper foil, placing the porcelain boat wrapped by the metal copper foil in a tube furnace, heating to 900 ℃ according to a heating rate of 5 ℃/min in a nitrogen atmosphere, and preserving heat for 2 hours to obtain the monoatomic catalyst.
FIG. 2 is a scanning electron microscope image of a prepared porous aza-carbon fiber supported copper single-atom catalyst, from which it can be seen that the obtained single-atom catalyst retains a precursor g-C after high-temperature carbonization 3 N 4 Fibrous structure of polyacrylonitrile fibers; FIG. 3 is a transmission electron microscope image of a single-atom catalyst, from which it can be seen that the sample is porous; FIG. 4 is a spherical aberration transmission electron microscope image of the prepared monoatomic catalyst, and the existence of copper monoatoms can be clearly seen from the image (the bright spots circled in the image are copper atoms); the specific surface area and pore volume of the prepared monoatomic catalyst are 604m respectively through nitrogen adsorption and desorption tests 2 /g and 1.7cm 3 /g; the mass content of copper in the monoatomic catalyst is 1.04% through atomic absorption spectrum test; FIG. 5 is a graph of the performance of the prepared sample in catalyzing an oxygen reduction reaction under alkaline conditions, from which it can be seen that the half-wave potential (0.82V) of the prepared sample is comparable to a commercial Pt/C catalyst.
Example 2
The preparation method of the monoatomic catalyst proposed in this example is different from that of example 1 only in that: will g-C 3 N 4 Nanosheet mother liquor and polyacrylonitrile mother liquor according to g-C 3 N 4 The mass ratio of the nano-sheets to the polyacrylonitrile is 1:2, and the spinning solution is obtained by mixing the nano-sheets and the polyacrylonitrile, and other steps and conditions are the same. The specific surface area and pore volume of the prepared monoatomic catalyst are 635m respectively 2 Per g and 1.72cm 3 Per gram, the existence of copper monoatoms is confirmed by a spherical aberration transmission electron microscope, and the mass content of copper in a sample is 1.13%; the prepared sample is used as an oxygen reduction catalyst, and the half-wave potential under alkaline conditions reaches 0.825V.
Example 3
The preparation method of the monoatomic catalyst proposed in this example differs from that of example 1 only in that: will g-C 3 N 4 Nanosheet mother liquor and polyacrylonitrile mother liquor according to g-C 3 N 4 The mass ratio of the nano-sheets to the polyacrylonitrile is 1:3, and the spinning solution is obtained by mixing the nano-sheets and the polyacrylonitrile, and other steps and conditions are the same. The specific surface area and pore volume of the prepared monoatomic catalyst are 657m respectively 2 Per g and 1.74cm 3 Per gram, the existence of copper monoatoms is confirmed by a spherical aberration transmission electron microscope, and the mass content of copper in the monoatomic catalyst is 1.21%; the prepared monoatomic catalyst is used as an oxygen reduction catalyst, and the half-wave potential under alkaline conditions reaches 0.83V.
Example 4
The preparation method of the monoatomic catalyst proposed in this example is different from that of example 1 only in that: the holding temperatures in the tube furnace were different, example 1 was 900 ℃, this example was 1000 ℃, and additionally iron foil was used instead of copper foil; specifically, the g-C 3 N 4 And (3) placing the polyacrylonitrile fibers in a porcelain boat, coating the top of the porcelain boat by using the metal iron foil, placing the porcelain boat wrapped by the metal iron foil in a tube furnace, heating to 1000 ℃ according to a heating rate of 5 ℃/min in a nitrogen atmosphere, and preserving heat for 2 hours to obtain the monoatomic catalyst.
The specific surface area and pore volume of the prepared monoatomic catalyst are 598m respectively 2 Per g and 1.66cm 3 Per gram, the existence of iron monoatoms is confirmed by a spherical aberration transmission electron microscope, and the mass content of iron in the monoatomic catalyst is 1.15%; the prepared monoatomic catalyst is used as an oxygen reduction catalyst in the following steps ofThe half-wave potential under alkaline conditions reaches 0.815V.
Example 5
The preparation method of the monoatomic catalyst proposed in this example is different from that of example 1 only in that: the holding temperatures in the tube furnace were different, example 1 was 900 ℃, this example was 1100 ℃, and the nickel foil was used instead of copper foil; specifically, the g-C 3 N 4 And (3) placing the polyacrylonitrile fibers in a porcelain boat, coating the top of the porcelain boat with the metal nickel foil, placing the porcelain boat wrapped by the metal nickel foil in a tube furnace, heating to 1100 ℃ according to a heating rate of 5 ℃/min in a nitrogen atmosphere, and preserving heat for 2 hours to obtain the monoatomic catalyst.
The specific surface area and pore volume of the prepared monoatomic catalyst are 576m respectively 2 /g and 1.69cm 3 The existence of nickel monoatoms is confirmed by a spherical aberration transmission electron microscope, and the mass content of nickel in the monoatomic catalyst is 1.11%; the prepared monoatomic catalyst is used as an oxygen reduction catalyst, and the half-wave potential under alkaline conditions reaches 0.835V.
Example 6
This example proposes a monoatomic catalyst prepared by the steps of:
calcining 10g melamine as a raw material for 3 hours at 600 ℃ under the protection of argon to obtain massive graphite-like carbon nitride, fully grinding 5g massive graphite-like carbon nitride, adding into 200mL deionized water, standing for 1 hour after ultrasonic treatment for 40min, taking supernatant, centrifuging at a rotation speed of 5000rpm, drying the centrifuged precipitate under a vacuum condition, and grinding to obtain g-C 3 N 4 Nanometer sheet, 1.7 g-C 3 N 4 Dispersing the nanosheets in 50mL of N, N' -Dimethylformamide (DMF) to obtain g-C 3 N 4 A nanosheet dispersion;
adding 5g of Polyacrylonitrile (PAN) into an anhydrous DMF solution, and stirring for 24 hours at 60 ℃ to obtain 29.4g of yellow-brown transparent polyacrylonitrile mother liquor, wherein the mass fraction of the polyacrylonitrile is 17%;
will g-C 3 N 4 Nanosheet mother liquor and polyacrylonitrile mother liquor according to g-C 3 N 4 The mass ratio of the nano-sheets to the polyacrylonitrile is 1:1, and the nano-sheets and the polyacrylonitrile are mixedObtaining spinning solution, and then adopting an electrostatic spinning method to prepare the g-C by taking the spinning solution as a raw material 3 N 4 Polyacrylonitrile fiber; specifically, selecting a needle with an inner diameter of 22 gauge, controlling the extrusion speed and the spinning voltage to be 0.1mm/min and 18KV respectively, and spinning to obtain g-C, wherein the distance between the needle and a receiving plate is 18cm 3 N 4 Polyacrylonitrile fiber;
the g-C 3 N 4 And (3) placing the polyacrylonitrile fibers in a porcelain boat, coating the top of the porcelain boat with a metal copper foil, placing the porcelain boat wrapped by the metal copper foil in a tube furnace, heating to 1000 ℃ according to the heating rate of 8 ℃/min in a nitrogen atmosphere, and preserving heat for 1h to obtain the monoatomic catalyst.
The specific surface area and pore volume of the prepared monoatomic catalyst are 577m respectively 2 Per g and 1.61cm 3 Per gram, the existence of copper monoatoms is confirmed by a spherical aberration transmission electron microscope, and the mass content of copper in the monoatomic catalyst is 1.02%; the prepared monoatomic catalyst is used as an oxygen reduction catalyst, and the half-wave potential under alkaline conditions reaches 0.8V.
Example 7
This example proposes a monoatomic catalyst prepared by the steps of:
calcining 10g melamine as a raw material for 3.5 hours under the protection of argon at 550 ℃ to obtain massive graphite-like carbon nitride, fully grinding 5g massive graphite-like carbon nitride, adding into 200mL deionized water, standing for 1 hour after ultrasonic treatment for 40min, taking supernatant, centrifuging at a rotation speed of 5000rpm, drying the centrifuged precipitate under vacuum condition, and grinding to obtain g-C 3 N 4 Nanometer sheet, 1.7 g-C 3 N 4 Dispersing the nanosheets in 50mL of N, N' -Dimethylformamide (DMF) to obtain g-C 3 N 4 A nanosheet dispersion;
adding 5g of Polyacrylonitrile (PAN) into an anhydrous DMF solution, and stirring for 24 hours at 60 ℃ to obtain 29.4g of yellow-brown transparent polyacrylonitrile mother liquor, wherein the mass fraction of the polyacrylonitrile is 17%;
will g-C 3 N 4 Nanosheet mother liquor and polyacrylonitrile mother liquor according to g-C 3 N 4 Nanosheets and polypropyleneMixing the acrylonitrile in a mass ratio of 1:3 to obtain a spinning solution, and preparing the g-C by taking the spinning solution as a raw material and adopting an electrostatic spinning method 3 N 4 Polyacrylonitrile fiber; specifically, selecting a needle with an inner diameter of 22 gauge, controlling the extrusion speed and the spinning voltage to be 0.1mm/min and 16KV respectively, and spinning to obtain g-C, wherein the distance between the needle and a receiving plate is 18cm 3 N 4 Polyacrylonitrile fiber;
the g-C 3 N 4 And (3) placing the polyacrylonitrile fibers in a porcelain boat, coating the top of the porcelain boat with a metal copper foil, placing the porcelain boat wrapped by the metal copper foil in a tube furnace, heating to 900 ℃ according to a heating rate of 2 ℃/min in a nitrogen atmosphere, and preserving heat for 3 hours to obtain the monoatomic catalyst.
The specific surface area and pore volume of the prepared monoatomic catalyst are 582m respectively 2 Per g and 1.73cm 3 Per gram, the existence of copper monoatoms is confirmed by a spherical aberration transmission electron microscope, and the mass content of copper in the monoatomic catalyst is 1.13%; the prepared monoatomic catalyst is used as an oxygen reduction catalyst, and the half-wave potential under alkaline conditions reaches 0.825V.
Example 8
This example proposes a monoatomic catalyst prepared by the steps of:
preparation of g-C by the procedure of example 1 3 N 4 Nanosheet mother liquor and polyacrylonitrile mother liquor;
will g-C 3 N 4 Nanosheet mother liquor and polyacrylonitrile mother liquor according to g-C 3 N 4 Mixing the nanosheets and polyacrylonitrile in a mass ratio of 1:3 to obtain a spinning solution, and then adopting the spinning solution as a raw material to prepare the g-C by adopting an electrostatic spinning method 3 N 4 Polyacrylonitrile fiber; specifically, selecting a needle with an inner diameter of 22 gauge, controlling the extrusion speed and the spinning voltage to be 0.1mm/min and 15KV respectively, and spinning to obtain g-C, wherein the distance between the needle and a receiving plate is 18cm 3 N 4 Polyacrylonitrile fiber;
the g-C 3 N 4 Placing polyacrylonitrile fiber in porcelain boat, coating the top of porcelain boat with metal copper foil, and then coating the metal copper foilThe porcelain boat is placed in a tube furnace, and the temperature is raised to 1000 ℃ according to the heating rate of 6 ℃/min in the nitrogen atmosphere, and the heat is preserved for 0.5h, so that the monoatomic catalyst is obtained.
The specific surface area and pore volume of the prepared monoatomic catalyst are 579m respectively 2 Per g and 1.65cm 3 Per gram, the existence of copper monoatoms is confirmed by a spherical aberration transmission electron microscope, and the mass content of copper in the monoatomic catalyst is 1.06%; the prepared monoatomic catalyst is used as an oxygen reduction catalyst, and the half-wave potential under alkaline conditions reaches 0.805V.
Other beneficial effects:
the method provided by the invention has the advantages of simple operation, low cost, high product yield, no subsequent pickling process, no use of a large amount of organic solvents, environmental protection, high efficiency and contribution to mass production.
The above-described embodiments of the present invention do not limit the scope of the present invention. Any other corresponding changes and modifications made in accordance with the technical idea of the present invention shall be included in the scope of the claims of the present invention.

Claims (9)

1. A method for preparing a monoatomic catalyst, comprising the steps of: coating g-C with metal foil 3 N 4 Heating polyacrylonitrile fiber to 900-1100 ℃ in an inert gas atmosphere, and preserving heat to obtain the monoatomic catalyst;
wherein the metal foil is copper foil, iron foil or nickel foil; the single-atom catalyst is used for catalyzing oxygen reduction reaction.
2. The method for preparing a monoatomic catalyst according to claim 1, wherein the rate of temperature rise is 2 to 8 ℃/min.
3. The method for preparing a monoatomic catalyst according to claim 1, wherein the time for the heat preservation is 0.5 to 3 hours.
4. A monoatomic according to claim 1A process for preparing a catalyst characterized in that the g-C 3 N 4 The polyacrylonitrile fiber is prepared by the following steps:
will g-C 3 N 4 Mixing the nanosheet mother solution and the polyacrylonitrile mother solution to obtain a spinning solution, and then adopting an electrostatic spinning method by taking the spinning solution as a raw material to prepare the g-C 3 N 4 Polyacrylonitrile fiber.
5. The method for preparing a monoatomic catalyst according to claim 4, wherein the catalyst is g-C 3 N 4 Nanosheet mother liquor and polyacrylonitrile mother liquor according to g-C 3 N 4 And mixing the nanosheets and the polyacrylonitrile in a mass ratio of 1:1-3 to obtain the spinning solution.
6. The method for preparing a monoatomic catalyst according to claim 4, wherein the catalyst is g-C 3 N 4 g-C in nanosheet mother liquor 3 N 4 The nano-sheet is prepared by the following steps: one or more of urea, dicyandiamide and melamine are used as raw materials, and the material is calcined at 500-600 ℃ under the protection of inert gas.
7. The method for preparing a monoatomic catalyst according to claim 6, wherein the calcination time is 3 to 4 hours.
8. The method for preparing a monoatomic catalyst according to claim 1, wherein the g-C 3 N 4 The polyacrylonitrile fiber is placed in a porcelain boat, and the top of the porcelain boat is coated by the metal foil.
9. A monoatomic catalyst prepared by the method of any one of claims 1 to 8.
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Title
High loading single-atom Cu dispersed on graphene for efficient oxygen reduction reaction;Guokang Han等;《Nano Energy》;第66卷;第1-9页 *

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