CN112499604A - Graphite-like phase carbon nitride material with nitrogen vacancy density and preparation method thereof - Google Patents

Graphite-like phase carbon nitride material with nitrogen vacancy density and preparation method thereof Download PDF

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CN112499604A
CN112499604A CN202011311437.9A CN202011311437A CN112499604A CN 112499604 A CN112499604 A CN 112499604A CN 202011311437 A CN202011311437 A CN 202011311437A CN 112499604 A CN112499604 A CN 112499604A
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graphite
carbon nitride
phase carbon
nitrogen
nitride material
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贺思如
洪序达
梁栋
郑海荣
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Shenzhen Institute of Advanced Technology of CAS
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Shenzhen Institute of Advanced Technology of CAS
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    • C—CHEMISTRY; METALLURGY
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
    • C01B21/0605—Binary compounds of nitrogen with carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM

Abstract

The application discloses a graphite-like phase carbon nitride material with nitrogen vacancy density and a preparation method thereof, belonging to the field of preparation of electron field emission materials. The preparation method comprises the following steps: obtaining graphite-like phase carbon nitride nanosheets; placing the graphite-like phase carbon nitride nanosheets in a hydrogen atmosphere for reduction to obtain a graphite-like phase carbon nitride material with nitrogen vacancy density; or heating the graphite-like phase carbon nitride nanosheets at a high temperature, and cooling the graphite-like phase carbon nitride nanosheets in the air after heating to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density. Through the mode, the intrinsic conductivity of the graphite-like phase carbon nitride material can be improved, so that the g-C is improved3N4The conductive performance of the material is enabled to show higher current density when field emission is carried out, and g-C is enlarged3N4The application range in the field of field emission.

Description

Graphite-like phase carbon nitride material with nitrogen vacancy density and preparation method thereof
Technical Field
The application relates to the field of preparation of electron field emission materials, in particular to a graphite-like phase carbon nitride material with nitrogen vacancy density and a preparation method thereof.
Background
Two-dimensional nanomaterials have a wide application prospect in a plurality of high-performance vacuum fields such as field emission displays and electron emission sources, and thus are receiving much attention. Two of the most important factors for a cathode material suitable for field emission are threshold voltage and current density, with lower threshold voltage representing lower power consumption and higher current density representing higher image definition. Since the field emission performance of the material can be significantly improved by incorporating nitrogen into the carbon-based material, graphite-like phase carbon nitride (g-C) having a structure similar to that of graphene, which can very effectively conduct heat and electricity, is used3N4) Is applied in field emission.
Graphite-like phase carbon nitride (g-C)3N4) Is a stack of sp2Orbital hybridization of a monoatomic structure of carbon and nitrogen atoms, and two-dimensional g-C3N4The nano sheet has large specific surface area, fewer layers and high aspect ratio, thereby having certain electrical conductivity and thermal conductivity.
However, even graphite-like phase carbon nitride (g-C)3N4) The nanoflakes have a structure extremely similar to graphene, g-C3N4Still considered as a poor conductive semiconductor, the main reason is that carbon in benzene ring is largely replaced by nitrogen in the structure, and the nitrogen content is as high as 57.1 wt.%, thereby resulting in low intrinsic conductivity of the material and presenting a problem of low current density in field emission application field.
Disclosure of Invention
The technical problem mainly solved by the application is to provide a graphite-like phase carbon nitride material with nitrogen vacancy density and a preparation method thereof, wherein the graphite-like phase carbon nitride (g-C) is reduced3N4) The nitrogen content in the material is such that the graphite-like phase carbon nitride (g-C)3N4) Nanoflakes have higher current densities in field emission.
In order to solve the above technical problem, one technical solution adopted by the present application is to provide a method for preparing a graphite-like phase carbon nitride material having a nitrogen vacancy density, the method comprising: obtaining graphite-like phase carbon nitride nanosheets; placing the graphite-like phase carbon nitride nanosheets in a hydrogen atmosphere for reduction to obtain a graphite-like phase carbon nitride material with nitrogen vacancy density; or heating the graphite-like phase carbon nitride nanosheets at a high temperature, and cooling the graphite-like phase carbon nitride nanosheets in the air after heating to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density.
The method comprises the following steps of placing graphite-like phase carbon nitride nanosheets in a hydrogen atmosphere for reduction to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density: and (3) placing the graphite-like phase carbon nitride nanosheets in a hydrogen atmosphere for reduction, controlling the reduction temperature to be 530-580 ℃ and the reduction time to be 50-70 min, so as to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density.
The method comprises the following steps of heating graphite-like phase carbon nitride nanosheets at a high temperature, cooling the graphite-like phase carbon nitride nanosheets in air after heating is completed, and obtaining the graphite-like phase carbon nitride material with the nitrogen vacancy density, wherein the steps comprise: and heating the graphite-like phase carbon nitride nanosheets at a high temperature, controlling the heating temperature to be 650-700 ℃, controlling the heating time to be 4-6 min, and cooling the graphite-like phase carbon nitride nanosheets in the air after the heating is finished to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density.
The method for obtaining the graphite-like phase carbon nitride nanosheets specifically comprises the following steps: obtaining organic matters rich in nitrogen elements; carrying out thermal polycondensation treatment on the organic matter rich in nitrogen element to obtain a blocky graphite-like phase carbon nitride material; grinding the blocky graphite-like phase carbon nitride material to obtain a powdery graphite-like phase carbon nitride material; placing the powdery graphite-like phase carbon nitride material in a stripping solvent to obtain mixed liquid; carrying out ultrasonic treatment on the mixed liquid to obtain a dispersion liquid; and (3) washing the dispersion liquid by adopting an organic solvent, and drying the washed dispersion liquid in vacuum to obtain the graphite-like phase carbon nitride nanosheet.
The method comprises the following steps of carrying out thermal polycondensation treatment on an organic matter rich in nitrogen element to obtain a blocky graphite-like phase carbon nitride material: and carrying out thermal polycondensation treatment on the organic matter rich in nitrogen element, controlling the thermal polycondensation temperature to be 530-580 ℃, and controlling the thermal polycondensation time to be 230-250 min, so as to obtain the blocky graphite-like phase carbon nitride material.
The method comprises the following steps of washing the dispersion liquid by using an organic solvent, and drying the washed dispersion liquid in vacuum to obtain the graphite-like phase carbon nitride nanosheet, wherein the step of washing the dispersion liquid by using the organic solvent further comprises the following steps: and controlling the temperature of vacuum drying to be 60-100 ℃.
Wherein, the organic matter rich in nitrogen element comprises any one of melamine, dicyandiamide, cyanamide or urea.
Wherein the stripping solvent comprises N-methyl pyrrolidone.
Wherein the organic solvent comprises isopropanol and/or ethanol.
In order to solve the above technical problem, the present application adopts a further technical solution of providing a graphite-like phase carbon nitride material having a nitrogen vacancy density, which is produced by any one of the above production methods.
The beneficial effect of this application is: distinguished from the prior art, the present application provides a graphite-like phase carbon nitride material having a nitrogen vacancy density by reducing graphite-like phase carbon nitride (g-C), and a method for preparing the same3N4) The content of nitrogen in the material can be increased by3N4Conductivity of the material, thereby making the graphite-like phase carbon nitride (g-C)3N4) Exhibits higher current density when field emission is performed. By adopting the mode, the graphite-like phase carbon nitride material prepared by the method can show better field emission performance, and the problem of g-C is solved3N4The problem of low current density in field emission applications expands the g-C3N4Application range in the field of field emission applications.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic flow chart diagram illustrating one embodiment of a method for producing a graphite-like phase carbon nitride material having a nitrogen vacancy density according to the present application;
FIG. 2 is a schematic flow chart diagram illustrating another embodiment of a method for producing a graphite-like phase carbon nitride material having a nitrogen vacancy density according to the present application;
FIG. 3 is a schematic flow chart diagram illustrating a process for preparing a graphite-like phase carbon nitride material having a nitrogen vacancy density according to another embodiment of the present application;
FIG. 4 is a schematic flow diagram of one embodiment of the present application for obtaining graphite-like carbon nitride nanoplates;
FIG. 5 is a schematic structural diagram of a graphite-like phase carbon nitride material having a nitrogen vacancy density according to the present application;
FIG. 6 is a comparative schematic view of TEM images of graphite-like phase carbon nitride materials obtained in example 1, example 2 and comparative example 1 of the present application;
fig. 7 is a comparative schematic view of field emission performance test charts of samples obtained in example 3, example 4, and comparative example 2 of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the examples of this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, the "plural" includes at least two in general, but does not exclude the presence of at least one.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
It should be understood that the terms "comprises," "comprising," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Two-dimensional nanomaterials have a wide application prospect in a plurality of high-performance vacuum fields such as field emission displays and electron emission sources, and thus are receiving much attention. Two of the most important factors for a cathode material suitable for field emission are threshold voltage and current density, with lower threshold voltage representing lower power consumption and higher current density representing higher image definition. Since the field emission performance of the material can be significantly improved by incorporating nitrogen into the carbon-based material, graphite-like phase carbon nitride (g-C) having a structure similar to that of graphene, which can very effectively conduct heat and electricity, is used3N4) Is applied in field emission.
Graphite-like phase carbon nitride (g-C)3N4) Is a stack of sp2Orbital hybridization of a monoatomic structure of carbon and nitrogen atoms, and two-dimensional g-C3N4The nano sheet has large specific surface area, fewer layers and high aspect ratio, thereby having certain electrical conductivity and thermal conductivity.
However, even graphite-like phase carbon nitride (g-C)3N4) The nanoflakes have a structure extremely similar to graphene, g-C3N4Is still considered to be conductiveThe main reason for the poor performance of semiconductors is that carbon in the benzene ring in the structure of the semiconductor is largely replaced by nitrogen, and the nitrogen content is as high as 57.1 wt.%, so that the intrinsic conductivity of the material is low, and the problems of high on-voltage, low current density, poor stability and the like are presented in the field emission application field.
The existing enhanced graphite-like phase carbon nitride (g-C)3N4) Methods for field emission properties, e.g. rapid synthesis of g-C using microwave heating3N4Two-dimensional materials, such that they exhibit a current density of 0.5mA/μm at an electric field strength of 0.5V/μm, however, g-C prepared in this manner3N4The two-dimensional material cannot exhibit a higher current density and cannot further increase the graphite-like phase carbon nitride (g-C)3N4) The field emission performance of (1).
Based on the above circumstances, the present application provides a graphite-like phase carbon nitride material having a nitrogen vacancy density by reducing graphite-like phase carbon nitride (g-C), and a method for preparing the same3N4) The nitrogen content in the material is such that the graphite-like phase carbon nitride (g-C)3N4) Nanoflakes have higher current densities in field emission.
The preparation method of the graphite-like phase carbon nitride material with the nitrogen vacancy density comprises the following steps: obtaining graphite-like phase carbon nitride nanosheets; placing the graphite-like phase carbon nitride nanosheets in a hydrogen atmosphere for reduction to obtain a graphite-like phase carbon nitride material with nitrogen vacancy density; or heating the graphite-like phase carbon nitride nanosheets at a high temperature, and cooling the graphite-like phase carbon nitride nanosheets in the air after heating to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density.
By reducing graphite-like phase carbon nitride (g-C)3N4) The content of nitrogen in the material can be increased by the application3N4Conductivity of the material, thereby making the graphite-like phase carbon nitride (g-C)3N4) The current density is higher when the field emission is carried out, and the field emission performance is better.
The present application will be described in detail below with reference to the drawings and embodiments.
Referring to fig. 1, fig. 1 is a schematic flow chart illustrating an embodiment of a method for producing a graphite-like carbon nitride material having a nitrogen vacancy density according to the present application. As shown in fig. 1, in the present embodiment, the preparation method includes:
s11: obtaining the graphite-like phase carbon nitride nanosheet.
In the present embodiment, the graphite-like carbon nitride nanosheets are a stack of sp-like carbon nitride nanosheets2The single atomic layer structure formed by orbital hybridization of carbon atoms and nitrogen atoms is similar to graphene and carbon nano tubes, and the two-dimensional g-C3N4The nano sheet has the advantages of large specific surface area, fewer layers, high aspect ratio and certain electrical and thermal conductivity.
In particular, since nitrogen has weak donor activity, the incorporation of nitrogen into a carbon-based material can significantly improve the field emission properties of the material, raise the fermi level of the material, lower the work function, and form more sp2And (4) clustering.
Further, g-C3N4The nano-sheet has abundant sp3Orbital hybridized geometric edges, not planar sp2Orbital hybrid structures, and thus a certain number of structural defects, corresponding to g-C3N4The edges of the nanosheets where localized states may exist reduce the electron tunneling barrier and thereby increase g-C3N4Field emission properties of the nanoplatelets.
S12: placing the graphite-like phase carbon nitride nanosheets in a hydrogen atmosphere for reduction to obtain a graphite-like phase carbon nitride material with nitrogen vacancy density; or heating the graphite-like phase carbon nitride nanosheets at a high temperature, and cooling the graphite-like phase carbon nitride nanosheets in the air after heating to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density.
In this embodiment, the graphite-like phase carbon nitride material having a nitrogen vacancy density is compared with the conventional g-C3N4The nitrogen content of the material is greatly reduced, and the intrinsic conductivity of the material is improved, so that the material has higher conductivity.
Unlike the prior art, the present embodiment employs hydrogen (H)2) Atmosphere reduction or high-temperature quenching process for graphiteAnd carrying out nitrogen reduction treatment on the phase carbon nitride nanosheets to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density. By reducing graphite-like phase carbon nitride (g-C)3N4) The content of nitrogen in the material can improve the intrinsic conductivity of the material, thereby improving the g-C3N4The conductive performance of the material is enabled to show higher current density when field emission is carried out, and g-C is enlarged3N4The material has application range in the field emission field.
With further reference to fig. 2, fig. 2 is a schematic flow chart illustrating another embodiment of a method for producing a graphite-like carbon nitride material having a nitrogen vacancy density according to the present application. As shown in fig. 2, in the present embodiment, the preparation method includes:
s21: obtaining the graphite-like phase carbon nitride nanosheet.
In the present embodiment, the graphite-like carbon nitride nanosheets are a stack of sp-like carbon nitride nanosheets2The single atomic layer structure formed by orbital hybridization of carbon atoms and nitrogen atoms is similar to graphene and carbon nano tubes, and the two-dimensional g-C3N4The nano sheet has the advantages of large specific surface area, fewer layers, high aspect ratio and certain electrical and thermal conductivity.
S22: and (3) placing the graphite-like phase carbon nitride nanosheets in a hydrogen atmosphere for reduction, controlling the reduction temperature to be 530-580 ℃ and the reduction time to be 50-70 min, so as to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density.
In the present embodiment, hydrogen (H) is used2) And (3) carrying out nitrogen reduction treatment on the graphite-like phase carbon nitride nanosheets in an atmosphere reduction mode, wherein the obtained graphite-like phase carbon nitride material powder with the nitrogen vacancy density is black.
Referring to fig. 3, fig. 3 is a schematic flow chart illustrating a method for preparing a graphite-like carbon nitride material having a nitrogen vacancy density according to another embodiment of the present disclosure. As shown in fig. 3, in the present embodiment, the preparation method includes:
s31: obtaining the graphite-like phase carbon nitride nanosheet.
In the present embodiment, the graphite-like carbon nitride nanosheets are a stack of sp-like carbon nitride nanosheets2Orbital hybridized carbon atomAnd nitrogen atoms, similar to graphene and carbon nanotubes, two-dimensional g-C3N4The nano sheet has the advantages of large specific surface area, fewer layers, high aspect ratio and certain electrical and thermal conductivity.
S32: and heating the graphite-like phase carbon nitride nanosheets at a high temperature, controlling the heating temperature to be 650-700 ℃, controlling the heating time to be 4-6 min, and cooling the graphite-like phase carbon nitride nanosheets in the air after the heating is finished to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density.
In the embodiment, the high-temperature quenching process is adopted to carry out nitrogen reduction treatment on the graphite-like phase carbon nitride nanosheets, and the obtained graphite-like phase carbon nitride material powder with the nitrogen vacancy density is black.
In the present embodiment, the graphite-like phase carbon nitride nanosheets are heated using a horizontal tube furnace.
Specifically, a horizontal tube test furnace is heated to 650-700 ℃, an alumina crucible with graphite-like phase carbon nitride nanosheets is placed in a target heating area, the heating time is controlled to be 4-6 min, the alumina crucible is taken out immediately after 4-6 min, and the graphite-like phase carbon nitride nanosheets are cooled in the air, so that the graphite-like phase carbon nitride material with the nitrogen vacancy density is obtained.
Wherein, the target heating area is the temperature sensor of the horizontal tube test furnace.
Referring to fig. 4, fig. 4 is a schematic flow chart of an embodiment of obtaining graphite-like carbon nitride nanosheets according to the present application. As shown in fig. 4, in the present embodiment, the method includes:
s41: obtaining the organic matter rich in nitrogen element.
In the present embodiment, the organic substance rich in nitrogen includes any of melamine, dicyandiamide, cyanamide, and urea.
S42: and carrying out thermal polycondensation treatment on the organic matter rich in nitrogen element to obtain the blocky graphite-like phase carbon nitride material.
In this embodiment, the thermal polycondensation temperature is controlled to 530 to 580 ℃ and the thermal polycondensation time is controlled to 230 to 250 min.
In the present embodiment, the bulk graphite-like phase carbon nitride material is yellow.
S43: and grinding the blocky graphite-like phase carbon nitride material to obtain the powdery graphite-like phase carbon nitride material.
S44: and placing the powdery graphite-like phase carbon nitride material in a stripping solvent to obtain mixed liquid.
In the present embodiment, the stripping solvent includes N-methylpyrrolidone.
S45: and carrying out ultrasonic treatment on the mixed liquid to obtain a dispersion liquid.
In this embodiment, the mixed liquid is placed in an ultrasonic field and treated with ultrasonic waves of appropriate frequency and power to ultrasonically strip the powdered graphite-like phase carbon nitride material.
Specifically, the mechanism of ultrasonic stripping is related to cavitation, bubbles caused by cavitation are distributed in the graphite-like phase carbon nitride sheet layer, when the bubbles are broken, micro airflow and vibration waves immediately act on the surface of the graphite-like phase carbon nitride powder, so that stress waves are expanded along the sheet layer, once compression waves are transmitted at the interface of the graphite-like phase carbon nitride powder, the stress waves are reflected back to act on the body, therefore, strong stress caused by breaking of a plurality of micro bubbles acts between the graphite-like phase carbon nitride sheet layers, which is equivalent to a powerful 'sucking disc', and the graphite-like phase carbon nitride sheet layer can be stripped, so that a single-layer or a few-layer graphite-like phase carbon nitride nanosheets can be obtained.
S46: and (3) washing the dispersion liquid by adopting an organic solvent, and drying the washed dispersion liquid in vacuum to obtain the graphite-like phase carbon nitride nanosheet.
In this embodiment, the organic solvent includes isopropyl alcohol and/or ethanol.
In this embodiment, the temperature of the vacuum drying is controlled to be 60 to 100 ℃.
Accordingly, the present application provides a graphite-like phase carbon nitride material having a density of nitrogen vacancies.
Referring to fig. 5, fig. 5 is a schematic structural diagram of a graphite-like carbon nitride material having a nitrogen vacancy density according to the present application.
In the present embodiment, the structural segment of the graphite-like phase carbon nitride material 50 having a nitrogen vacancy density includes carbon 1, nitrogen 2, and nitrogen vacancies 3.
Different from the prior art, the graphite-like phase carbon nitride material with the nitrogen vacancy density provided by the application has the advantages that the nitrogen content is greatly reduced due to the nitrogen vacancies, so that the intrinsic conductivity is higher, the conductivity is also improved, and higher current density can be shown during field emission.
The following non-limiting examples are provided to facilitate an understanding of the embodiments of the present application and are set forth in the detailed description to provide further explanation of the embodiments of the present application.
EXAMPLE 1
Obtaining melamine; carrying out thermal polycondensation treatment on melamine to obtain a blocky graphite-like phase carbon nitride material; grinding the blocky graphite-like phase carbon nitride material to obtain a powdery graphite-like phase carbon nitride material; putting the powdery graphite-like phase carbon nitride material into N-methyl pyrrolidone to obtain mixed liquid; carrying out ultrasonic treatment on the mixed liquid to obtain a dispersion liquid; washing the dispersion with isopropanol and ethanol, and vacuum drying the washed dispersion to obtain graphite-like carbon nitride (g-C)3N4) Nanosheets; g to C3N4The nanosheet is reduced in a hydrogen atmosphere to obtain g-C with nitrogen vacancy density3N4Two-dimensional nanosheets.
Example 2
Obtaining melamine; carrying out thermal polycondensation treatment on melamine to obtain a blocky graphite-like phase carbon nitride material; grinding the blocky graphite-like phase carbon nitride material to obtain a powdery graphite-like phase carbon nitride material; putting the powdery graphite-like phase carbon nitride material into N-methyl pyrrolidone to obtain mixed liquid; carrying out ultrasonic treatment on the mixed liquid to obtain a dispersion liquid; washing the dispersion with isopropanol and ethanol, and vacuum drying the washed dispersion to obtain graphite-like carbon nitride (g-C)3N4) Nanosheets; g to C3N4Heating the nanosheet at high temperature, and cooling in air after heating to obtain g-C with nitrogen vacancy density3N4Two-dimensional nanosheets.
Comparative example 1
Obtaining melamine; carrying out thermal polycondensation treatment on melamine to obtain a blocky graphite-like phase carbon nitride material; grinding the blocky graphite-like phase carbon nitride material to obtain a powdery graphite-like phase carbon nitride material; putting the powdery graphite-like phase carbon nitride material into N-methyl pyrrolidone to obtain mixed liquid; carrying out ultrasonic treatment on the mixed liquid to obtain a dispersion liquid; washing the dispersion with isopropanol and ethanol, and vacuum drying the washed dispersion to obtain graphite-like carbon nitride (g-C)3N4) Nanosheets.
The microscopic morphology of the obtained graphite-like phase carbon nitride material was observed by Transmission Electron Microscopy (TEM) for examples 1 and 2 and comparative example 1.
Specifically, referring to fig. 6, fig. 6 is a schematic diagram showing a TEM image of a graphite-like phase carbon nitride material obtained in example 1, example 2 and comparative example 1 of the present application. Wherein FIG. 6a is g-C having a nitrogen vacancy density in example 1 of the present application3N4TEM image of nanosheets, FIG. 6b is g-C with nitrogen vacancy density of example 2 of the present application3N4TEM image of nanosheets, FIG. 6C is g-C in comparative example 1 of the present application3N4TEM images of the nanoplates.
As can be seen from FIG. 6, hydrogen (H) was used2) g-C with nitrogen vacancy density obtained after nitrogen reduction treatment is carried out on graphite-like phase carbon nitride nanosheets by atmosphere reduction or high-temperature quenching process3N4The nano sheets are all provided with folds, which shows that the number of layers of the material obtained by the graphite-like phase carbon nitride material after the nitrogen reduction treatment and the ultrasonic stripping is less; and due to the use of hydrogen (H)2) g-C with nitrogen vacancy density obtained by reduction in atmosphere3N4The wrinkling of the nanoflakes is more pronounced, indicating that the g-C with nitrogen vacancy density3N4The number of material layers of the nano-thin sheet after ultrasonic stripping is less, namely H2The reduction under the atmosphere is more beneficial to nitrogen evolution of the material, and more single-layer g-C can be stripped3N4A nanoflake; further, it was shown that when N-methylpyrrolidone was used as a stripping solvent, the solvent was used for g-C3N4The material is mechanically stripped to obtain better stripping effect.
The elements of the obtained graphite-like phase carbon nitride material were measured by atomic emission spectrometry (ICP) for examples 1 and 2 and comparative example 1, and the measurement results are shown in table 1:
TABLE 1
Figure BDA0002789964200000111
As can be seen from the above table, hydrogen (H) is used2) g-C with nitrogen vacancy density obtained after nitrogen reduction treatment is carried out on graphite-like phase carbon nitride nanosheets by atmosphere reduction or high-temperature quenching process3N4The nitrogen content in the nanoflakes all decreased, indicating that hydrogen (H) was used2) The nitrogen can be effectively reduced by the atmosphere reduction or high-temperature quenching process; further, the lower nitrogen content of the material in example 1 indicates that hydrogen (H) is used2) Atmospheric reduction pair g-C3N4The nitrogen reduction effect of the material is more obvious.
Example 3
Preparing the following raw materials by weight: graphite-like phase carbon nitride (g-C) having nitrogen vacancy density3N4) Nanoflakes, 52 parts, wherein the g-C has a nitrogen vacancy density3N4The nano-flake is prepared by adopting hydrogen (H)2) Preparing by atmosphere reduction; 13 parts of ethyl cellulose; terpineol, 35 parts; g-C having a nitrogen vacancy density3N4Mixing the nano-flakes, ethyl cellulose and terpineol according to the raw material ratio, and feeding the mixture into a ball mill for ball milling for 60min to obtain uniform slurry; a small amount of the slurry was coated on a copper substrate under nitrogen (N)2) Calcining and removing slurry under atmosphere, controlling the calcining temperature to be 420 ℃, and controlling the calcining timeThe time is 6 h.
Example 4
Preparing the following raw materials by weight: graphite-like phase carbon nitride (g-C) having nitrogen vacancy density3N4) Nanoflakes, 52 parts, wherein the g-C has a nitrogen vacancy density3N4The nano-sheet is prepared by adopting a high-temperature quenching process; 13 parts of ethyl cellulose; terpineol, 35 parts; g-C having a nitrogen vacancy density3N4Mixing the nano-flakes, ethyl cellulose and terpineol according to the raw material ratio, and feeding the mixture into a ball mill for ball milling for 60min to obtain uniform slurry; a small amount of the slurry was coated on a copper substrate under nitrogen (N)2) Calcining and removing slurry under the atmosphere, wherein the calcining temperature is controlled to be 420 ℃, and the calcining time is controlled to be 6 h.
Comparative example 2
Preparing the following raw materials by weight: graphite-like phase carbon nitride (g-C)3N4) 52 parts of nanosheet; 13 parts of ethyl cellulose; terpineol, 35 parts; g to C3N4Mixing the nanosheets, the ethyl cellulose and the terpineol according to the raw material ratio, and feeding the mixture into a ball mill for ball milling for 60min to obtain uniform slurry; a small amount of the slurry was coated on a copper substrate under nitrogen (N)2) Calcining and removing slurry under the atmosphere, wherein the calcining temperature is controlled to be 420 ℃, and the calcining time is controlled to be 6 h.
The samples obtained were subjected to field emission performance tests for examples 3 and 4 and comparative example 2.
Specifically, referring to fig. 7, fig. 7 is a comparison diagram of field emission performance test charts of samples obtained in example 3, example 4 and comparative example 2 of the present application.
In this embodiment, curve 1 is a test chart of field emission performance of the sample obtained in example 3, curve 2 is a test chart of field emission performance of the sample obtained in example 4, and curve 3 is a test chart of field emission performance of the sample obtained in comparative example 2.
As can be seen from FIG. 7, g-C having a nitrogen vacancy density at the same electric field strength3N4Compared with non-nitrogen-reduced g-C3N4Has the advantages of higher current density,and g-C having a nitrogen vacancy density3N4Higher current densities were also exhibited at lower turn-on voltages, indicating modified g-C3N4The two-dimensional material has better field emission performance; further, hydrogen (H) is used2) Atmosphere reduced g-C3N4When the turn-on voltage is 2.1V/mum and the field strength is 4.52V/mum, the voltage can show 4.3mA/cm2Current density of (2), indicating the use of hydrogen (H)2) Atmosphere reduced g-C3N4Can exhibit extremely excellent field emission performance.
Unlike the prior art, the present embodiment employs hydrogen (H)2) And (3) carrying out nitrogen reduction treatment on the graphite-like phase carbon nitride nanosheets by an atmosphere reduction or high-temperature quenching process to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density. By reducing graphite-like phase carbon nitride (g-C)3N4) The content of nitrogen in the material can improve the intrinsic conductivity of the material, thereby improving the g-C3N4The conductive performance of the conductive material enables the conductive material to show higher current density when the starting voltage is lower during field emission, and g-C is enlarged3N4The application range in the field of field emission.
The above description is only for the purpose of illustrating embodiments of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application or are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.

Claims (10)

1. A method for producing a graphite-like phase carbon nitride material having a nitrogen vacancy density, the method comprising:
obtaining graphite-like phase carbon nitride nanosheets;
placing the graphite-like phase carbon nitride nanosheets in a hydrogen atmosphere for reduction to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density; or the like, or, alternatively,
and heating the graphite-like phase carbon nitride nanosheets at a high temperature, and cooling the graphite-like phase carbon nitride nanosheets in the air after heating to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density.
2. The preparation method according to claim 1, wherein the step of reducing the graphite-like phase carbon nitride nanosheets in a hydrogen atmosphere to obtain the graphite-like phase carbon nitride material having a nitrogen vacancy density specifically comprises:
and (3) placing the graphite-like phase carbon nitride nanosheets in a hydrogen atmosphere for reduction, controlling the reduction temperature to be 530-580 ℃ and the reduction time to be 50-70 min, so as to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density.
3. The preparation method according to claim 1, wherein the step of heating the graphite-like phase carbon nitride nanosheets at a high temperature and cooling the graphite-like phase carbon nitride nanosheets in air after the heating is completed to obtain the graphite-like phase carbon nitride material having the nitrogen vacancy density specifically comprises:
and heating the graphite-like phase carbon nitride nanosheets at a high temperature, controlling the heating temperature to be 650-700 ℃, controlling the heating time to be 4-6 min, and cooling the graphite-like phase carbon nitride nanosheets in the air after heating is completed to obtain the graphite-like phase carbon nitride material with the nitrogen vacancy density.
4. The preparation method according to claim 1, wherein the step of obtaining graphite-like phase carbon nitride nanosheets specifically comprises:
obtaining organic matters rich in nitrogen elements;
carrying out thermal polycondensation treatment on the organic matter rich in the nitrogen element to obtain a blocky graphite-like phase carbon nitride material;
grinding the blocky graphite-like phase carbon nitride material to obtain a powdery graphite-like phase carbon nitride material;
placing the powdery graphite-like phase carbon nitride material in a stripping solvent to obtain mixed liquid;
carrying out ultrasonic treatment on the mixed liquid to obtain a dispersion liquid;
and washing the dispersion liquid by adopting an organic solvent, and drying the washed dispersion liquid in vacuum to obtain the graphite-like phase carbon nitride nanosheet.
5. The preparation method according to claim 4, wherein the step of performing thermal polycondensation treatment on the nitrogen-rich organic matter to obtain the bulk graphite-like phase carbon nitride material specifically comprises:
and carrying out thermal polycondensation treatment on the organic matter rich in the nitrogen element, controlling the thermal polycondensation temperature to be 530-580 ℃, and controlling the thermal polycondensation time to be 230-250 min, so as to obtain the blocky graphite-like phase carbon nitride material.
6. The preparation method according to claim 5, wherein the step of washing the dispersion with an organic solvent and vacuum-drying the washed dispersion to obtain the graphite-like phase carbon nitride nanosheets further comprises:
and controlling the temperature of vacuum drying to be 60-100 ℃.
7. The method according to claim 4, wherein the nitrogen-rich organic substance comprises any one of melamine, dicyandiamide, cyanamide, or urea.
8. The production method according to claim 4, wherein the stripping solvent comprises N-methylpyrrolidone.
9. The method of claim 4, wherein the organic solvent comprises isopropanol, and/or ethanol.
10. A graphite-like phase carbon nitride material having a nitrogen vacancy density, characterized in that it is produced by the production method according to any one of claims 1 to 9.
CN202011311437.9A 2020-11-20 2020-11-20 Graphite-like phase carbon nitride material with nitrogen vacancy density and preparation method thereof Pending CN112499604A (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104401948A (en) * 2014-11-17 2015-03-11 长安大学 Preparation method for single-layer graphite-type carbon nitride nanosheet solution

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104401948A (en) * 2014-11-17 2015-03-11 长安大学 Preparation method for single-layer graphite-type carbon nitride nanosheet solution

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PING NIU等: ""Distinctive defects engineering in graphitic carbon nitride for greatly extended visible light photocatalytic hydrogen evolution"", 《NANO ENERGY》 *
PING NIU等: ""Increasing the Visible Light Absorption of Graphitic Carbon Nitride (Melon) Photocatalysts by Homogeneous Self-Modification with Nitrogen Vacancies"", 《ADVANCED MATERIALS》 *

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Application publication date: 20210316