CN109761207B

CN109761207B - 3D graphite phase carbon nitride material and preparation method thereof

Info

Publication number: CN109761207B
Application number: CN201910090066.7A
Authority: CN
Inventors: 姜德胜; 严鹏程; 徐丽; 李赫楠
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2019-01-30
Filing date: 2019-01-30
Publication date: 2022-06-21
Anticipated expiration: 2039-01-30
Also published as: CN109761207A

Abstract

The invention belongs to the technical field of material preparation, photocatalysis and photoelectrocatalysis, and discloses a 3D graphite phase carbon nitride material and a preparation method thereof. The ionic liquid 1-alkyl-3-methylimidazole halogen salt can be used as a template agent and a dispersing agent, and the 3D spherical Carbon Nitride (CN) is successfully prepared by a method of combining an ionic liquid soft template method with a precursor after calcination and hydrothermal treatment. The 3D spherical CN has smaller forbidden bandwidth than the common block CN, improves the utilization rate of light, improves the easy recombination of the light-induced electrons and holes, thereby improving the performance of the CN and widening the application range of the CN. The method takes the basic chemical raw materials as the starting raw materials to prepare the high-performance catalyst, has the advantages of rich raw materials, high preparation yield, low cost, no toxicity, no harm, environmental friendliness, simple process and easy batch production.

Description

3D graphite phase carbon nitride material and preparation method thereof

Technical Field

The invention belongs to the technical field of material preparation and photocatalysis and photoelectrocatalysis, and relates to a preparation method of a three-dimensional (3D) graphite phase carbon nitride material.

Background

Graphite phase Carbon Nitride (CN) is used as a novel polymer semiconductor material, has an environment-friendly, high chemical stability, good antibacterial property, an adjustable band gap structure and excellent optical/electrical performance, and has attracted extensive attention of scientific researchers. Currently, CN has therefore been widely used in photocatalytic water cracking, photocatalytic pollutant degradation, artificial photosynthesis, carbon dioxide reduction, and the like. However, the recombination of photo-generated electron-hole pairs is still very severe, and the utilization rate of light is low, which also limits the wider application of the photo-generated electron-hole pairs. In order to further improve the performance of CN, researchers have tried strategies such as structural design, element doping, heterojunction formation with other elements, and filling defect creation. In particular, in terms of the design of the nano structure of CN, the structures such as porous, layered, nano-sheet, nano-rod, nano-tube and quantum dot are prepared, which have been reported to increase the specific surface area, improve the visible light absorption performance, promote mass transfer, expose more active sites and improve the performance. According to research, it is found that these unique structures are mainly prepared by hard templates and soft templates. In contrast, hard templates often require cumbersome synthetic steps and toxic chemicals to remove the template. The soft template does not need to be removed, so that the production complexity is reduced, and the production cost is further reduced. CN materials prepared with soft templates so far include 3D assembled nanostructures, porous nanosheets, laver layered structures, worm-like porous structures, etc. Therefore, it can be concluded that the construction of 3DCN by ionic liquid halide salts as soft templates is feasible.

Disclosure of Invention

The invention aims to provide a preparation method of 3D CN, which solves the problems that CN photon-generated carriers are easy to recombine and the light utilization rate is low. The preparation method is simple and the cost is low.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of 3D CN specifically comprises the following steps:

(1) weighing melamine and ionic liquid 1-alkyl-3-methylimidazole halogen salt, putting the melamine and ionic liquid into a polytetrafluoroethylene lining reaction kettle, adding deionized water, stirring uniformly, transferring into an oven for reaction, centrifugally collecting, washing with absolute ethyl alcohol and deionized water for several times, and drying in the oven to obtain a precursor;

the structural formula of the 1-alkyl-3-methylimidazole halogen salt is as follows:

wherein, R is one of ethyl, propyl, butyl, amyl, hexyl, octyl, dodecyl, tetradecyl and hexadecyl, and X is one of chlorine, bromine or iodine;

(2) and (2) putting the precursor obtained in the step (1) into an alumina crucible, covering the alumina crucible with a cover, moving the alumina crucible into a muffle furnace, heating to 650 ℃ at a certain heating rate in an air atmosphere, and keeping the temperature for 3-5h to obtain the 3D graphite phase carbon nitride material, namely 3D CN powder.

In the step (1), the dosage proportion of melamine, ionic liquid 1-alkyl-3-methylimidazole halogen salt and deionized water is 2-3 g: 0.5-2 mol: 30-40 mL.

In the step (1), the reaction temperature in the oven is 160-200 ℃, and the reaction time is 12-14 h; the drying temperature in the oven is 40-80 deg.C, and the drying time is 12-18 h.

In the step (2), the heating rate is 1-5 ℃/min.

The invention has the beneficial effects that:

(1) the invention utilizes ionic liquid 1-alkyl-3-methylimidazole halide salt as a template agent and a dispersing agent, and successfully prepares the 3D spherical CN by combining an ionic liquid soft template method with a precursor after hydrothermal calcination.

(2) The forbidden bandwidth of the 3D spherical CN is smaller than that of the common block CN, so that the utilization rate of light is improved, and the phenomenon that the light-generated electrons and holes are easy to recombine is improved, thereby improving the performance of the CN. The ionic liquid is used as a soft template agent, so that the complex steps in a hard template method are avoided, the contact with organic toxic substances is avoided, and the production cost is reduced. The method takes basic chemical raw materials as starting raw materials to prepare the high-performance catalyst, and has the advantages of rich raw materials, high preparation yield, low cost, no toxicity, no harm and environmental friendliness. In addition, the preparation process is simple and easy for batch production.

Drawings

Figure 1 is an X-ray diffraction (XRD) pattern of a 3D CN material.

FIG. 2 is a Fourier Infrared Spectroscopy (FT-IR) plot of 3D CN material.

FIG. 3 is a Scanning Electron Microscope (SEM) image of a 3D CN material, wherein a is a SEM image of the 3D CN material, and b is a SEM image of the CN material.

FIG. 4 is a solid ultraviolet Diffuse Reflectance (DRS) plot (a) of a 3D CN material; and (b) a corresponding forbidden band width diagram.

Fig. 5 is a graph of photocurrent in buffer for 3D CN material.

Detailed Description

The test methods used in the following examples are all conventional methods unless otherwise specified.

Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

Example 1:

step 1, preparation of a precursor:

3g of melamine and 0.5mol of ionic liquid 1-hexadecyl-3-methylimidazolium bromide are weighed and placed into a clean polytetrafluoroethylene lining reaction kettle, and 35mL of deionized water is added. After stirring evenly, the mixture is moved to an oven to react for 12 hours at 200 ℃. And (4) centrifuging and collecting. Washing with absolute ethyl alcohol and deionized water for several times, and drying in a drying oven at 40 ℃ for 12h to obtain the precursor.

Step 2, preparation of 3D CN:

2g of the precursor obtained in the step 1 is put into an alumina crucible, and a cover is covered. The powder was transferred to a muffle furnace and heated to 500 ℃ at a rate of 2 ℃ per minute in an air atmosphere for 4 hours to obtain 3D CN powder.

Example 2:

step 1, preparation of a precursor:

weighing 4g of melamine and 1.0mol of ionic liquid 1-hexadecyl-3-methylimidazolium chloride, putting the melamine and the ionic liquid into a clean polytetrafluoroethylene lining reaction kettle, and adding 30mL of deionized water. After being stirred uniformly, the mixture is moved to an oven to react for 12 hours at 180 ℃. And (4) centrifuging and collecting. Washing with absolute ethyl alcohol and deionized water for several times, and drying in a 50 ℃ oven for 8h to obtain the precursor.

Step 2, preparation of 3D CN:

3g of the precursor obtained in the step 1 is put into an alumina crucible, and a cover is covered. The powder was transferred to a muffle furnace and heated to 550 ℃ at a rate of 2 ℃ per minute in an air atmosphere for 3 hours to obtain 3D CN powder.

Example 3:

step 1, preparation of a precursor:

2g of melamine and 2mol of ionic liquid 1-hexadecyl-3-methylimidazolium bromide are weighed and placed into a clean polytetrafluoroethylene-lined reaction kettle, and 40mL of deionized water is added. After stirring uniformly, moving to an oven for reaction at 160 ℃ for 14 h. And (4) centrifuging and collecting. Washing with absolute ethyl alcohol and deionized water for several times, and drying in an oven at 80 ℃ for 18h to obtain the precursor.

Step 2, preparation of 3D CN:

3g of the precursor obtained in the step 1 is put into an alumina crucible, and a cover is covered. The powder was transferred to a muffle furnace and heated to 650 ℃ at a rate of 3 ℃ per minute in an air atmosphere for 5 hours to obtain 3D CN powder.

Figure 1 is an X-ray diffraction (XRD) pattern of a 3D CN material. As can be seen from the figure, 3D CN and CN have the same diffraction signature peaks, indicating the nature of both crystalline phases. Wherein, the characteristic peak of 13.11 degrees corresponds to the (100) crystal face of the graphite phase carbon nitride, and the characteristic peak belongs to the (002) crystal face. The strength of the characteristic peak of the 3D CN is obviously weaker than that of the CN, and the 13.11-degree characteristic peak of the CN almost disappears, which shows that the thickness of the 3D CN prepared by the ionic liquid soft template method is obviously superior to that of the CN.

FIG. 2 is a Fourier Infrared Spectroscopy (FT-IR) plot of 3D CN material. As can be seen from the figure, the peak positions of 3D CN and CN are consistent with the peak shapes, indicating that having the same ionic liquid soft template method does not destroy the main structure of CN. Wherein, is located at 810cm^-1The characteristic peak of (A) is attributed to the respiratory vibration of the s-triazine ring; 900-1800cm^-1One class of peaks belongs to the vibrational peaks of C ═ N and C — N heterocycles; 3000-3600cm^-1The peak at (a) is mainly caused by the N — H stretching vibration.

Fig. 3 is a Scanning Electron Microscope (SEM) image of the 3D CN material. Wherein, the figure a is the SEM image of 3D CN, and the figure b is the SEM image of CN. From figure a it can be seen that the nanosheets were successfully assembled into a spherical structure, forming a 3D CN. Panel b shows CN as a nano-platelet structure. This shows that the ionic liquid 1-hexadecyl-3-methylimidazolium bromide can be used as a soft template agent for preparing 3D spherical CN.

FIG. 4 is a solid ultraviolet Diffuse Reflectance (DRS) plot (a) of a 3D CN material; the corresponding forbidden band width diagram (b). It can be seen from fig. a that 3D CN has stronger absorption than CN in both visible and ultraviolet regions, and in addition, 3D CN shows narrower band gap than CN (fig. b). This shows that 3D CN can utilize light more efficiently to generate more photogenerated electron-hole pairs, which is beneficial to the separation of photogenerated electrons and holes, and makes it have better photoelectric properties.

FIG. 5 is a photo-amperometric graph of 3D CN material in 0.1mol/L phosphate buffer. Under the irradiation of light, different materials respond to light differently, and the generated photocurrent intensity is also different. The ability to separate photogenerated carriers of different materials can therefore be demonstrated by producing photocurrents of different intensities. As can be seen from the figure, 3D CN has a higher photocurrent value than CN, which indicates that 3DCN has faster charge transfer capability than CN, promotes efficient separation of photo-generated electrons from holes, and thus has better performance.

Claims

1. A preparation method of a 3D graphite phase carbon nitride material is characterized by comprising the following steps: the method comprises the following steps:

2. The method of claim 1, wherein the method comprises: in the step (1), the dosage proportion of melamine, ionic liquid 1-alkyl-3-methylimidazole halogen salt and deionized water is 2-3 g: 0.5-2 mol: 30-40 mL.

3. The method of claim 1, wherein the method comprises: in the step (1), the reaction temperature in the oven is 160-200 ℃, and the reaction time is 12-14 h; the drying temperature in the oven is 40-80 deg.C, and the drying time is 12-18 h.

4. The method of claim 1, wherein the method comprises: in the step (2), the heating rate is 1-5 ℃/min.