阅读说明：本技术 一种具有良好可见光响应的c6n7氮化碳材料及其制备方法与应用 (C with good visible light response6N7Carbon nitride material and preparation method and application thereof ) 是由 谭华桥 赵鑫宇 于 2020-05-21 设计创作，主要内容包括：一种具有良好可见光响应的C<Sub>6</Sub>N<Sub>7</Sub>氮化碳材料及其制备方法与应用,属于光催化材料技术领域。解决了现有技术中没有C<Sub>6</Sub>N<Sub>7</Sub>结构的氮化碳材料的制备方法的问题。本发明的C<Sub>6</Sub>N<Sub>7</Sub>氮化碳材料的制备方法：将化合物A与化合物B按物质的量比(1-3):1混合均匀,得到的混合物在空气或惰性气氛下,425-700℃反应1h以上,冷却,得到C<Sub>6</Sub>N<Sub>7</Sub>氮化碳材料,其中,化合物A为尿素、单氰胺、硫脲中的一种或多种,化合物B为草酰二胺、草酸中的一种或多种。该C<Sub>6</Sub>N<Sub>7</Sub>氮化碳材料的制备方法简单,成本低,便于大规模生产,制备的C<Sub>6</Sub>N<Sub>7</Sub>氮化碳材料为具有多孔的层状结构,物理化学性质稳定,导电性好,可见光响应性良好,光催化活性高。(C with good visible light response 6 N 7 A carbon nitride material, a preparation method and application thereof, belonging to the technical field of photocatalytic materials. Solves the problem that the prior art does not have C 6 N 7 A method for producing a carbon nitride material having a structure. C of the invention 6 N 7 The preparation method of the carbon nitride material comprises the following steps: uniformly mixing the compound A and the compound B according to the mass ratio (1-3):1, reacting the obtained mixture at 425 ℃ and 700 ℃ for more than 1h in air or inert atmosphere, and cooling to obtain C 6 N 7 The carbon nitride material comprises a compound A and a compound B, wherein the compound A is one or more of urea, cyanamide and thiourea, and the compound B is one or more of oxalyl diamine and oxalic acid. The C is 6 N 7 Of carbon nitride materialsSimple preparation method, low cost, convenient large-scale production and prepared C 6 N 7 The carbon nitride material has a porous layered structure, stable physical and chemical properties, good conductivity, good visible light response and high photocatalytic activity.)

1.C₆N₇The preparation method of the carbon nitride material is characterized by comprising the following steps of:

step one, uniformly mixing a compound A and a compound B according to the mass ratio (1-3) to 1 to obtain a mixture;

the compound A is one or more of urea, cyanamide and thiourea;

the compound B is one or more of oxalyl diamine and oxalic acid;

step two, under the air or inert atmosphere, the mixture obtained in the step one reacts for more than 1h at the reaction temperature of 425 ℃ and 700 ℃, and is cooled to obtain C₆N₇A carbon nitride material.

2. C according to claim 1₆N₇The method for preparing the carbon nitride material is characterized in that the mass ratio of the compound A to the compound B is 2: 1.

3. C according to claim 1₆N₇The preparation method of the carbon nitride material is characterized in that the reaction temperature is 450-650 ℃.

4. C according to claim 1₆N₇The preparation method of the carbon nitride material is characterized in that the reaction time is 3 h.

5. C according to claim 1₆N₇A method for producing a carbon nitride material, characterized in that the temperature is raised to the reaction temperature at a temperature raising rate of 20 ℃/min or less.

6. C according to claim 5₆N₇The preparation method of the carbon nitride material is characterized in that the heating rate is 5 ℃/min.

7. C according to any of claims 1 to 6₆N₇Preparation method of carbon nitride material C₆N₇A carbon nitride material.

8. C of claim 7₆N₇Use of carbon nitride materials as photocatalysts.

9. C according to claim 8₆N₇Use of a carbon nitride material as a photocatalyst, characterized in that C₆N₇Carbon nitride material in photocatalysis hydrogen production, photocatalysis carbon dioxide reduction, photocatalysis nitrogen gas conversion into ammonia gas, photocatalysis diphenyl hydrazine oxidation, photocatalysis benzylamine oxidation, photocatalysis phenol degradation, photocatalysis halogenated phenol degradation, photocatalysis tetracycline degradation, photocatalysis methyl orange degradation, photocatalysis Cr⁶⁺Reduction, photocatalytic removal of NO₂The use of (1).

Technical Field

The invention belongs to the technical field of photocatalytic materials, and particularly relates to a C with good visible light response₆N₇A carbon nitride material, a preparation method and application thereof.

Background

Graphite phase carbon nitride (g-C)₃N₄) Has the advantages of low price, no toxicity, stable physical and chemical properties, relatively high photocatalytic activity and the like, and is an ideal photocatalyst. Has wide application in the aspects of photocatalytic hydrogen production, oxygen production, carbon dioxide reduction, catalytic organic reaction, sewage treatment and environmental protection.

Conventional g-C₃N₄The forbidden band width is about 2.88eV, only visible light with the wavelength less than or equal to 460nm can be absorbed, and the specific surface area is low, the photogenerated carriers are quickly compounded, and the conductivity is poor, thereby limiting the g-C to a certain extent₃N₄The practical application of (1). For this purpose, a series of methods, for example: morphology, structure regulation, doping or covalent modification, composite construction of heterojunctions with other semiconductor materials, and the like are reported successively to improve g-C₃N₄Photocatalytic activity of (1). But receive g-C₃N₄Sp in self structure³The limitation of N connection, the conjugation, visible light absorption, and the transmission and separation of photogenerated carriers have not been developed in a breakthrough manner. Thus, g-C was fundamentally changed₃N₄The development of a novel carbon nitride material with novel structure, high conjugation, good stability and wide visible light response range becomes an important challenge in the fields of photocatalysis and materials.

Recently, a series of heptazine ring-based carbon nitride materials with novel structures are predicted, a series of optimization and theoretical prediction are carried out on the structures and the physical and chemical properties of the materials, and the results show that the C of the heptazine ring directly connected through a C-C bond₆N₇Is a potentially excellent class of photocatalysts. Unfortunately, their synthesis has not been reported in the literature to date.

Disclosure of Invention

The invention aims to solve the problem that the prior art does not have C₆N₇The technical problem of the preparation method of the carbon nitride material with the structure is to provide C with good visible light response₆N₇A carbon nitride material, a preparation method and application thereof.

C of the invention₆N₇Preparation method of carbon nitride materialThe method comprises the following steps:

step one, uniformly mixing a compound A and a compound B according to the mass ratio (1-3) to 1 to obtain a mixture;

the compound A is one or more of urea, cyanamide and thiourea;

the compound B is one or more of oxalyl diamine and oxalic acid;

step two, under the air or inert atmosphere, the mixture obtained in the step one reacts for more than 1h at the reaction temperature of 425 ℃ and 700 ℃, and is cooled to obtain C₆N₇A carbon nitride material.

Preferably, the mass ratio of compound a to compound B is 2: 1.

Preferably, the reaction temperature is 450-.

Preferably, the reaction time is 3 h.

The temperature is preferably raised to the reaction temperature at a temperature raising rate of 20 ℃/min or less, and more preferably at a temperature raising rate of 5 ℃/min.

The present invention also provides the above-mentioned compound C₆N₇Preparation method of carbon nitride material C₆N₇A carbon nitride material.

The present invention also provides the above-mentioned compound C₆N₇Use of carbon nitride materials as photocatalysts.

Preferably, C is₆N₇Carbon nitride material in photocatalysis hydrogen production, photocatalysis carbon dioxide reduction, photocatalysis nitrogen gas conversion into ammonia gas, photocatalysis diphenyl hydrazine oxidation, photocatalysis benzylamine oxidation, photocatalysis phenol degradation, photocatalysis halogenated phenol degradation, photocatalysis tetracycline degradation, photocatalysis methyl orange degradation, photocatalysis Cr⁶⁺Reduction, photocatalytic removal of NO₂The use of (1).

Compared with the prior art, the invention has the beneficial effects that:

c of the invention₆N₇The carbon nitride material is prepared from nitrogen-rich small molecule containing single carbon atom, urea, mononitrile amine or thiourea, and oxalyl diamine or oxalic acid with C-C connection at a certain ratioExample mixing, by simple high temperature thermal polymerization, C is first achieved₆N₇The visible light catalytic activity of the photocatalyst is systematically studied. The preparation method is simple, low in cost and convenient for large-scale production.

C of the invention₆N₇The carbon nitride material has a porous layered structure, stable physical and chemical properties, good conductivity, good visible light response and high photocatalytic activity.

C of the invention₆N₇The carbon nitride material is used for photocatalytic hydrogen production, photocatalytic carbon dioxide reduction, photocatalytic nitrogen conversion into ammonia gas, photocatalytic diphenyl hydrazine and benzylamine oxidation, photocatalytic phenol, halogenated phenol, tetracycline and methyl orange degradation, and photocatalytic Cr⁶⁺Reduction and photocatalytic removal of NO and NO₂In addition, the method has great potential application value. Through test detection, under the irradiation of visible light, the photocatalytic hydrogen production amount of the carbon nitride material prepared by the method is 6 times that of carbon nitride prepared by taking urea as a precursor and 34 times that of carbon nitride prepared by taking melamine as the precursor; c prepared by the invention₆N₇In the reaction of catalyzing the oxidation of diphenyl hydrazine and degrading halogenated phenol by light, the conversion rate and the selectivity of the carbon nitride material are close to 100 percent.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is apparent that the drawings in the following disclosure are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

In FIG. 1, (a) and (b) are both C prepared in example 3 of the present invention₆N₇Scanning electron micrographs of carbon nitride, (C) and (d) are both C prepared in inventive example 3₆N₇Transmission electron micrographs of carbon nitride material;

FIG. 2 shows a graph of C prepared in example 3 of the present invention₆N₇Atomic force microscopy of carbon nitride;

FIG. 3 is the thickness of the solid line of FIG. 2 swept across the nanoplatelets;

FIG. 4 is C prepared according to example 3 of the present invention₆N₇X-ray energy spectrum analysis of carbon nitride;

FIG. 5 is C prepared according to example 3 of the present invention₆N₇X-ray powder diffraction pattern (XRD) of carbon nitride;

FIG. 6 shows a graph of C prepared in example 3 of the present invention₆N₇Solid carbon nuclear magnetic spectrum of carbon nitride;

FIG. 7 shows a graph of C prepared in example 3 of the present invention₆N₇Liquid carbon nuclear magnetic spectrum of carbon nitride;

in FIG. 8, (a) and (b) are each C prepared in example 3 of the present invention₆N₇X-ray photoelectron spectroscopy (XPS) fine spectra of C and N of carbon nitride;

FIG. 9 shows a graph of C prepared in example 3 of the present invention₆N₇Infrared spectroscopy of carbon nitride;

FIG. 10 is C prepared according to example 3 of the present invention₆N₇Raman spectrum of carbon nitride;

FIG. 11 is C prepared according to example 3 of the present invention₆N₇N of carbon nitride₂Adsorption curve diagram;

in FIG. 12, (a) is C prepared in example 3 of the present invention₆N₇UV-VISIBLE SOLID DIFFUSION SPECTRUM OF CARBON NITRIDE, wherein (b) is C prepared in EXAMPLE 3 of THE INVENTION₆N₇Carbon nitride forbidden band width; (c) c prepared for inventive example 3₆N₇Schottky curve of carbon nitride; (d) c prepared for inventive example 3₆N₇A valence band photoelectron spectrum of carbon nitride;

FIG. 13 is C prepared according to example 3 of the present invention₆N₇Electron paramagnetic resonance spectroscopy of carbon nitride;

FIG. 14 shows a graph of C prepared in example 3 of the present invention₆N₇Transient surface photovoltage spectra of carbon nitride;

FIG. 15 is C prepared according to example 3 of the present invention₆N₇Electrochemical impedance spectroscopy of carbon nitride;

FIG. 16 shows an embodiment of the present inventionExample 3 preparation of C₆N₇Photocurrent response of carbon nitride;

FIG. 17 is C prepared according to example 3 of the present invention₆N₇A line graph of a photocatalytic hydrogen evolution reaction of carbon nitride;

FIG. 18 is C prepared according to example 3 of the present invention₆N₇The relationship between the quantum efficiency of carbon nitride and the spectral absorption wavelength;

FIG. 19 is C prepared according to example 3 of the present invention₆N₇Detecting a spectrogram of the superoxide radical by using electron paramagnetic resonance in a photocatalytic diphenyl hydrazine oxidation experiment by using carbon nitride;

FIG. 20 shows C prepared in examples 1-5 of the present invention₆N₇X-ray powder diffraction of carbon nitride;

FIG. 21 shows C prepared in examples 1-5 of the present invention₆N₇A solid diffuse reflectance spectrum of carbon nitride;

FIG. 22 shows C prepared in examples 1-5 of the present invention₆N₇Photocatalytic hydrogen production data of carbon nitride;

FIG. 23 is C prepared according to example 6 of the present invention₆N₇X-ray powder diffraction pattern of carbon nitride;

FIG. 24 is C prepared according to example 6 of the present invention₆N₇A solid diffuse reflectance spectrum of carbon nitride;

FIG. 25 is C prepared according to example 6 of the present invention₆N₇Photocatalytic hydrogen production data of carbon nitride;

FIG. 26 is C prepared according to example 7 of the present invention₆N₇X-ray powder diffraction of carbon nitride;

FIG. 27 is C prepared according to example 7 of the present invention₆N₇A solid diffuse reflectance spectrum of carbon nitride;

FIG. 28 is C prepared according to example 8 of the present invention₆N₇X-ray powder diffraction of carbon nitride;

FIG. 29 shows a graph of C prepared in example 8 of the present invention₆N₇A solid diffuse reflectance spectrum of carbon nitride;

FIG. 30 shows C prepared in examples 7 and 8 of the present invention₆N₇Photocatalysis of carbon nitrideHydrogen production data;

FIG. 31 shows a drawing C of the present invention₆N₇Synthetic scheme for the preparation of carbon nitride.

Detailed Description

For a further understanding of the invention, preferred embodiments of the invention are disclosed below in conjunction with the detailed description, but it is to be understood that this disclosure is only intended to further illustrate features and advantages of the invention, and is not intended to limit the claims to the invention.

C of the invention₆N₇The preparation method of the carbon nitride comprises the following steps:

step one, uniformly mixing a compound A and a compound B according to the mass ratio (1-3) to 1 to obtain a mixture;

step two, under the air or inert atmosphere, the mixture obtained in the step one reacts for more than 1h at the reaction temperature of 425 ℃ and 700 ℃, and is cooled to obtain C₆N₇A carbon nitride material.

In the technical scheme, in the first step, the compound A is one or more of urea, cyanamide and thiourea which are mixed according to any proportion, the compound B is one or more of oxalyl diamine and oxalic acid which are mixed according to any proportion, and the mass ratio of the compound A to the compound B is preferably 2: 1. The mode of mixing uniformly is not particularly limited, and it is usually grinding mixing uniformly.

In the technical scheme, in the second step, the reaction temperature must be controlled to be 425-700 ℃, and if the temperature is lower than 400 ℃, heptazine ring cannot be formed; if the temperature is above 700 ℃, C₆N₇Carbon nitride material is unstable leading to thermal decomposition; the preferred reaction temperature is 450-650 ℃. The reaction time is preferably 3 hours. The heating apparatus usually employs a muffle furnace. Since the yield is higher when the temperature is raised to the reaction temperature at a temperature raising rate of 20 ℃/min or less, the temperature is preferably raised to the reaction temperature at a temperature raising rate of 20 ℃/min or less, and more preferably at a temperature raising rate of 5 ℃/min.

Taking urea as an example, the invention C₆N₇The production route of the carbon nitride material is shown in fig. 31.

C of the invention₆N₇The preparation principle of the carbon nitride material is as follows: oxalyldiamide (compound B) can be condensed with urea (compound A) and then deaminated by dehydration to form a heptazine ring, i.e. C, connected by a C-C single bond₆N₇Ring to obtain C₆N₇A carbon nitride material.

The present invention also provides the above-mentioned compound C₆N₇Preparation method of carbon nitride material C₆N₇A carbon nitride material.

The present invention also provides the above-mentioned compound C₆N₇Use of carbon nitride materials as photocatalysts. Specifically, the carbon nitride material is used for photocatalytic hydrogen production, photocatalytic carbon dioxide reduction, photocatalytic nitrogen conversion into ammonia gas, photocatalytic diphenylhydrazine oxidation, photocatalytic benzylamine oxidation, photocatalytic phenol degradation, photocatalytic halogenated phenol degradation, photocatalytic tetracycline degradation, photocatalytic methyl orange degradation, photocatalytic Cr degradation⁶⁺Reduction, photocatalytic removal of NO₂The use of (1).