CN110339853A - C3N5 material and its preparation method and application - Google Patents

Abstract

_The invention relates to a _C3N5 material preparation method and application thereof, and belongs to the technical field of photocatalysis. The technical problem solved by the present invention is to provide a kind of C ₃ N ₅ preparation method of material, the method comprises the following steps: a, 3-amino-1,2,4-triazole and six-membered nitrogen-heterocyclic ring in weight ratio 1 : 0.8～1.2 mixing to obtain a mixed powder, wherein the six-membered nitrogen heterocyclic ring is at least one of cyanuric acid and barbituric acid; b, heating up the mixed powder at 480～520°C Keep it warm for 2.5-3.5 hours, take it out after cooling, wash and dry to obtain C ₃ N ₅ material. When preparing the C ₃ N ₅ material, the present invention adopts 3-amino-1,2,4-triazole and a specific six-membered nitrogen heterocycle as raw materials, and the preparation method is simple, and the C ₃ N ₅ material thus obtained , which has good photocatalytic activity and can be widely used as a photocatalyst.

Description

C3N5 material and its preparation method and application

technical field

_The invention relates to a _C3N5 material and its preparation method and application, and belongs to the technical field of photocatalysis.

Background technique

Photocatalytic technology is a technology that uses photocatalysts to catalyze reactions under light irradiation. It is a green technology that has important application prospects in the fields of energy and the environment. Photocatalyst is the key to photocatalytic technology. It is a general term for chemical substances that can play a catalytic role under the excitation of photons. Semiconductor photocatalysts can be excited to generate electrons and holes under the irradiation of light, and redox reactions occur on the semiconductor surface. So as to realize the decomposition of water or the decomposition of organic pollutants, and realize the utilization and transformation of light energy.

As a new type of semiconductor material, C ₃ N ₅ has become a research hotspot due to its unique composition, structure and visible light catalytic activity. Compared with the existing more researched C ₃ N ₄ materials, C ₃ N ₅ has higher diffusion-limited current density and lower overpotential, which makes it have better photocatalytic performance. At present, there are some reports on the preparation methods of C ₃ N ₅ , but there are few reports on its specific structure, and the C ₃ N ₅ materials prepared by different methods have different photocatalytic activities, which may be due to the different methods brought about by the difference in its structure.

C ₃ N ₅ can be prepared by self-assembly of 5-amino-1H-tetrazole (5-ATTZ), for example: In Young Kim et al. in the literature "Ordered mesoporous C ₃ N ₅ with triazole and triazine skeletons and its graphene composites" (Dr.In YoungKim, Sungho Kim, Dr.Xiaoyan Jin, Dr.Selvarajan Premkumar, Dr.Goutam Chandra, Dr.Nam-Suk Lee, Prof.Gurudas P.Mane, Prof. Seong-Ju Hwang, Prof. Siva Umapathy, Prof. Ajayan Vinu. Ordered Mesoporous C3N5 with a Combined Triazole and TriazineFramework and Its Graphene Hybrids for the Oxygen Reduction Reaction(ORR)[J].Angewandte Chemie,2018,130(52).)

The preparation of C ₃ N ₅ can also be prepared by using 3-amino-1,2,4-triazole as raw material. For example, in patent CN109562940A, C ₃ N ₅ materials. The photocatalytic performance of the material prepared by this method needs to be further improved.

And Zhang Youyu of Hunan Normal University studied the C ₃ N ₅ material prepared from 3-amino-1,2,4-triazole with the assistance of NaOH, and found that with the increase of NaOH concentration, the N of gC ₃ N ₅ The vacancies gradually increase, showing excellent photocatalytic and photoelectrochemical properties. (For details, see the literature "Porous graphitic carbon nitride with controllable nitrogen vacancies: an ideal catalyst for enhancing the visible light degradation of pollutants", Haiyan Wang, Mingxia Li, Huan Li, Qiujun Lu, Youyu Zhang, ShouzhuoYao. Porous graphitic carbon nitride with controllable nitrogen vacancies: Aspromising catalyst for enhanced degradation of pollutant under visible light[J].Materials&Design,2018.) In addition, they also studied 3-amino-1,2,4-triazole as raw material with the assistance of KBr The C ₃ N ₅ material was prepared, and it was found that compared with the directly prepared material, the C ₃ N ₅ material obtained with the assistance of KBr also showed significantly superior photocatalytic performance. (For details, see the literature "Salt-directed synthesis of mesoporous rod-like gC ₃ N ₅ : as an excellent photocatalyst for the degradation of organic pollutants", Wang, Haiyan, Li, Mingxia, Lu, Qiujun, et al. A mesoporousrod-like g-C3N5synthesized by salt-guided strategy: as a superior photocatalyst for degradation of organic pollutant [J]. ACS Sustainable Chemistry & Engineering.)

Contents of the invention

The first technical problem to be solved by the present invention is to provide a preparation method of C ₃ N ₅ material, and the material prepared by the method shows better photocatalytic performance compared with the existing method.

_The preparation method of the _C3N5 material of the present invention comprises the following steps:

a. Mixing: Mix 3-amino-1,2,4-triazole and six-membered nitrogen heterocycle at a weight ratio of 1:0.8 to 1.2 to obtain a mixed powder, wherein the six-membered nitrogen heterocycle is At least one of cyanuric acid and barbituric acid;

b. Calcination: heat up the mixed powder, keep it at 480-520° C. for 2.5-3.5 hours, take it out after cooling, wash and dry to obtain a C ₃ N ₅ material.

Preferably, the specific operation of step a is: add 3-amino-1,2,4-triazole and six-membered nitrogen heterocycle into absolute ethanol, stir for 1-3 hours, then sonicate for 0.5-1.5 hours, 60- Dry at 80°C to obtain a powder after mixing. It is more preferred to stir for 2h, then sonicate for 1h, and dry at 70°C.

Preferably, in step a, the six-membered nitrogen heterocycle is cyanuric acid. More preferably, 3-amino-1,2,4-triazole and cyanuric acid are mixed in a weight ratio of 1:1.

Another preferred, in step a, the six-membered nitrogen heterocyclic ring is cyanuric acid and barbituric acid. More preferably, by weight ratio, 3-amino-1,2,4-triazole:cyanuric acid:barbituric acid=1:1:0.1.

Preferably, in step b, the heating rate is 3-8°C/min, preferably 5°C/min.

As a preferred solution, step c is carried out after step a, and step c is: add the mixed powder into the auxiliary agent solution, stir evenly, then dry, and then carry out step b with the dried powder; the auxiliary agent Sodium hydroxide or potassium bromide.

Preferably, the concentration of the auxiliary agent solution is 0.05-0.15 g/mL, more preferably the concentration of the auxiliary agent solution is 0.1 g/mL.

Preferably, the weight ratio of auxiliary agent to 3-amino-1,2,4-triazole is 1:10-20, more preferably the weight ratio of auxiliary agent to 3-amino-1,2,4-triazole is 1 :15.

The second technical problem solved by the present invention is to provide a C ₃ N ₅ material.

The C ₃ N ₅ material of the present invention is prepared by the above method. It can be seen from the ultraviolet diffuse reflectance and fluorescence emission spectra that the photocatalytic activity of the material is better than that of the C ₃ N ₅ material prepared by the existing method.

The present invention also provides the application of the C ₃ N ₅ material described in the present invention in photocatalyst.

The C ₃ N ₅ material of the invention has better photocatalytic activity and can be used in photocatalysts. The C ₃ N ₅ material of the present invention can be used alone as a photocatalyst, or mixed with other photocatalysts.

Compared with the prior art, the present invention has the following beneficial effects:

When preparing the C ₃ N ₅ material, the present invention uses 3-amino-1,2,4-triazole mixed with a specific six-membered nitrogen heterocycle as a raw material. The preparation method is simple, and the C ₃ N ₅ material thus obtained , which has good photocatalytic activity and can be widely used as a photocatalyst.

Description of drawings

Fig. 1 is the XRD patterns of C ₃ N ₅ prepared in Examples 1-4 and Comparative Examples 1-2 of the present invention.

Fig. 2 is the ultraviolet diffuse reflectance spectrum of C ₃ N ₅ prepared in Examples 1-4 and Comparative Examples 1-2 of the present invention.

Fig. 3 is a fluorescence emission spectrum of C ₃ N ₅ prepared in Examples 1-4 and Comparative Examples 1-2 of the present invention under excitation at 366 nm.

Detailed ways

_The preparation method of the _C3N5 material of the present invention comprises the following steps:

a. Mixing: Mix 3-amino-1,2,4-triazole and six-membered nitrogen heterocycle at a weight ratio of 1:0.8 to 1.2 to obtain a mixed powder, wherein the six-membered nitrogen heterocycle is At least one of cyanuric acid and barbituric acid;

b. Calcination: heat the mixed powder at 480-520° C. for 2.5-3.5 hours, take it out after cooling, wash and dry to obtain a C ₃ N ₅ material.

Step a is mainly to mix the raw materials according to the proportion. Preferably, the specific operation of step a is: add 3-amino-1,2,4-triazole and six-membered nitrogen heterocycle to absolute ethanol, stir for 1～ 3h, then sonicate for 0.5-1.5h, and dry at 60-80°C to obtain a mixed powder; preferably stir for 2h, then sonicate for 1h, and dry at 70°C.

As one of the implementations, in step a, the six-membered nitrogen heterocycle is cyanuric acid. Preferably, 3-amino-1,2,4-triazole and cyanuric acid are mixed in a weight ratio of 1:1.

As another embodiment, in step a, the six-membered nitrogen heterocycle is cyanuric acid and barbituric acid. Studies have shown that the photocatalytic activity of the _C3N5 material obtained after adding ₃ -amino-1,2,4-triazole, cyanuric acid and barbituric acid is better than that of only adding 3-amino-1 , the addition of 2,4-triazole and cyanuric acid, namely barbituric acid, is beneficial to improve the photocatalytic properties of the synthesized materials. Preferably, by weight, 3-amino-1,2,4-triazole:cyanuric acid:barbituric acid=1:1:0.1.

Step b is the process of obtaining the C ₃ N ₅ material by calcination. The calcination of this step does not require a protective gas and can be carried out in the air. The operation is simple and there is no special requirement for the calcination equipment. For example, the mixed powder can be directly put into the muffle furnace for heating and calcination.

Preferably, in step b, the heating rate is 3-8°C/min, preferably 5°C/min.

As a preferred solution, step c is performed after step a, and step c is: add the mixed powder into the auxiliary agent solution, stir evenly, then dry, and then perform step b on the dried powder; the auxiliary agent Sodium hydroxide or potassium bromide. After adding additives, the performance of the obtained C ₃ N ₅ material is better.

Preferably, the concentration of the auxiliary agent solution is 0.05-0.15 g/mL, more preferably the concentration of the auxiliary agent solution is 0.1 g/mL.

Preferably, the weight ratio of auxiliary agent to 3-amino-1,2,4-triazole is 1:10-20, more preferably the weight ratio of auxiliary agent to 3-amino-1,2,4-triazole is 1 :15.

The C ₃ N ₅ material of the present invention is prepared by the above method. It can be seen from the ultraviolet diffuse reflectance and fluorescence emission spectra that the photocatalytic activity of the material is better than that of the C ₃ N ₅ material prepared by the existing method.

The present invention also provides the application of the C ₃ N ₅ material described in the present invention in photocatalyst.

The C ₃ N ₅ material of the invention has better photocatalytic activity and can be used in photocatalysts. The C ₃ N ₅ material of the present invention can be used alone as a photocatalyst, or mixed with other photocatalysts.

The specific implementation of the present invention will be further described below in conjunction with the examples, and the present invention is not limited to the scope of the examples.

Example 1

Weigh 5g of 3-amino-1,2,4-triazole and 5g of cyanuric acid into a beaker and add 100mL of absolute ethanol, then stir the suspension at ambient temperature for 2h, then sonicate at room temperature Processing 1h. Then the suspension was dried in an oven at 70°C to obtain a powder, which was put into a 50mL crucible with a lid, moved to a muffle furnace at a rate of 5°C/min to 500°C and then kept for 3 hours. After cooling, put the sample into a beaker and add 100mL of distilled water, then place it in an ultrasonic machine for ultrasonic dispersion for 3h, then centrifuge and dry the sample to obtain a C ₃ N ₅ material, which is designated as 3-C-1. The XRD spectrum of the material is shown in Figure 1, the ultraviolet diffuse reflectance spectrum is shown in Figure 2, and the fluorescence emission spectrum under 366nm excitation is shown in Figure 3.

Example 2

Weigh 5g of 3-amino-1,2,4-triazole, 5g of cyanuric acid and 0.5g of barbituric acid into a beaker and add 100mL of absolute ethanol, then put the suspension at ambient temperature Stir for 2 h, then sonicate for 1 h at room temperature. Then the suspension was dried in an oven at 70 °C to obtain a white powder, which was put into a 50 mL crucible with a lid, moved to a muffle furnace at a heating rate of 5 °C/min to 500 °C and then kept for 3 h. After cooling, put the sample into a beaker and add 100mL of distilled water, then place it in an ultrasonic machine for ultrasonic dispersion for 3h, then centrifuge the sample and dry it to obtain a C ₃ N ₅ material, which is designated as 3-C-1-2. The XRD spectrum of the material is shown in Figure 1, the ultraviolet diffuse reflectance spectrum is shown in Figure 2, and the fluorescence emission spectrum under 366nm excitation is shown in Figure 3.

Example 3

Weigh 4.5g of 3-amino-1,2,4-triazole and 4.5g of cyanuric acid into a beaker and add 100mL of absolute ethanol, then stir the suspension at ambient temperature for 2h, then at room temperature Ultrasonic treatment for 1h. Then the suspension was dried in an oven at 70°C to obtain a powder, and KBr solution (0.3g of KBr was added to 3mL of distilled water) was added and stirred evenly, then dried in an oven at 80°C to obtain a solid, which was transferred into a 50mL In a crucible with a lid, move to a muffle furnace to raise the temperature to 500°C at a rate of 5°C/min, and then keep it warm for 3h. After cooling, put the sample into a beaker and add 100mL of distilled water, then place it in an ultrasonic machine for ultrasonic dispersion for 3h, wash the sample several times, centrifuge and dry to obtain a C ₃ N ₅ material, which is designated as 3-CK-1. The XRD spectrum of the material is shown in Figure 1, the ultraviolet diffuse reflectance spectrum is shown in Figure 2, and the fluorescence emission spectrum under 366nm excitation is shown in Figure 3.

Example 4

Weigh 4.5g of 3-amino-1,2,4-triazole, 4.5g of cyanuric acid and 0.45g of barbituric acid into a beaker and add 100mL of absolute ethanol, then place the suspension in ambient Stir at room temperature for 2 h, then sonicate for 1 h at room temperature. Then the suspension was dried in an oven at 70°C to obtain a powder, and KBr solution (0.3g of KBr was added to 3mL of distilled water) was added and stirred evenly, then dried in an oven at 80°C to obtain a solid, which was transferred into a 50mL In a crucible with a lid, move to a muffle furnace to raise the temperature to 500°C at a rate of 5°C/min, and then keep it warm for 3h. After cooling, put the sample into a beaker and add 100mL of distilled water, then put it into an ultrasonic machine for ultrasonic dispersion for 3h, wash the sample several times, centrifuge and dry to obtain a C ₃ N ₅ material, denoted as 3-CK-1-2 . The XRD spectrum of the material is shown in Figure 1, the ultraviolet diffuse reflectance spectrum is shown in Figure 2, and the fluorescence emission spectrum under 366nm excitation is shown in Figure 3.

Comparative example 1

Weigh 6g of 3-amino-1,2,4-triazole into a 50mL crucible with a lid, move to a muffle furnace to raise the temperature to 500°C at a rate of 5°C/min, and then keep it warm for 3h. After cooling, put the sample into a beaker and add 100mL of distilled water, then place it in an ultrasonic machine for ultrasonic dispersion for 3h, then centrifuge and dry the sample to obtain a C ₃ N ₅ material, which is designated as 3-C. The XRD spectrum of the material is shown in Figure 1, the ultraviolet diffuse reflectance spectrum is shown in Figure 2, and the fluorescence emission spectrum under 366nm excitation is shown in Figure 3.

Comparative example 2

Weigh 4.5g of 3-amino-1,2,4-triazole into a beaker, add KBr solution (0.3g of KBr into 3mL of distilled water) and stir evenly, then put it in an oven at 80°C to dry to obtain a solid , moved it into a 50mL crucible with a lid, moved it to a muffle furnace, raised the temperature to 500°C at a rate of 5°C/min, and then kept it for 3h. After cooling, put the sample into a beaker and add 100mL of distilled water, then put it into an ultrasonic machine for ultrasonic dispersion for 3h, wash the sample several times, centrifuge and dry to obtain a C ₃ N ₅ material, which is denoted as 3-CK. The XRD spectrum of the material is shown in Figure 1, the ultraviolet diffuse reflectance spectrum is shown in Figure 2, and the fluorescence emission spectrum under 366nm excitation is shown in Figure 3.

Fig. ₁ is the XRD spectrum of the _C3N5 prepared by Examples 1-4 and Comparative Examples 1-2 of the present invention. As can be seen from Fig. ₁ , it is different from the _C3N5 material prepared by the existing method Compared with Comparative Examples 1-3), the XRD diffraction peak of the material prepared by the method of the present invention is consistent with the diffraction peak position of the C ₃ N ₅ material prepared by the existing method. It can be seen that the present invention successfully prepared the C ₃ N ₅ material , and the XRD diffraction peak of the C ₃ N ₅ material obtained by the present invention is wider than that of the C ₃ N ₅ material prepared by the existing method, indicating that the crystal form has decreased and the specific surface area has increased, which is beneficial to the improvement of photocatalytic performance .

Fig. ₂ is the ultraviolet diffuse reflectance spectrum of _C3N5 prepared by Examples 1-4 and Comparative Examples 1-2 of the present invention. It can be seen from the spectrum that compared with the _{C3N5 material} prepared by the existing method , The material prepared by the method of the present invention has a wider absorption spectrum range, which is more conducive to realizing photocatalysis under visible light or sunlight.

Fig. 3 is a fluorescence emission spectrum of C ₃ N ₅ prepared in Examples 1-4 and Comparative Examples 1-2 of the present invention under excitation at 366 nm. It is well known to those skilled in the art that photocatalysts will generate electrons and holes after being excited by light, and some of the electrons and holes will play a redox role, and the other part will recombine, and the energy will be released in the form of light. Therefore, the lower the intensity of fluorescence emission, the lower the electron-hole recombination rate, indicating the higher photocatalytic activity. As can be seen from Figure ₃ , the _C3N5 material prepared by the method of the present invention has a fluorescence emission intensity lower than that of the _C3N5 material prepared by the existing method, indicating that the _{C3N5 material} obtained by the method _of the present invention has High photocatalytic activity. The photocatalytic activity of 3-C-1-2 was better than that of 3-C-1, and that of 3-CK-1-2 was better than that of 3-CK-1, indicating that barbituric acid and three The photocatalytic activity of C ₃ N ₅ materials with polycyanuric acid is higher than that with only cyanuric acid added. In addition, the photocatalytic activity of 3-CK-1 is better than that of 3-C-1, and the photocatalytic activity of 3-CK-1-2 is better than that of 3-C-1-2, indicating that the addition of auxiliary agent potassium bromide helps to improve the photocatalytic activity of the material.

Claims (10)

1. The preparation method of C ₃ N ₅ material, is characterized in that, comprises the steps: a. Mixing: Mix 3-amino-1,2,4-triazole and six-membered nitrogen heterocycle at a weight ratio of 1:0.8 to 1.2 to obtain a mixed powder, wherein the six-membered nitrogen heterocycle is At least one of cyanuric acid and barbituric acid; b. Calcination: heat up the mixed powder, keep it at 480-520° C. for 2.5-3.5 hours, take it out after cooling, wash and dry to obtain a C ₃ N ₅ material. 2. The preparation method of C ₃ N ₅ materials according to claim 1, characterized in that: the specific operation of step a is: adding 3-amino-1,2,4-triazole and six-membered azacyclic Stir in water and ethanol for 1-3 hours, then sonicate for 0.5-1.5 hours, and dry at 60-80°C to obtain a mixed powder; preferably stir for 2 hours, then sonicate for 1 hour, and dry at 70°C. 3. The preparation method of C ₃ N ₅ materials according to claim 1, characterized in that: in step a, the six-membered nitrogen heterocycle is cyanuric acid, preferably 3-amino-1,2,4-triazole Mix with cyanuric acid at a weight ratio of 1:1. 4. C according to claim 1 The preparation method of ₃ N ₅ materials is characterized in that: in step a, the six-membered nitrogen heterocycle is cyanuric acid and barbituric acid, preferably by weight, 3-amino -1,2,4-triazole:cyanuric acid:barbituric acid=1:1:0.1. 5 . The preparation method of C ₃ N ₅ material according to claim 1 , characterized in that: in step b, the heating rate is 3-8° C./min, preferably 5° C./min. 6. The preparation method of C ₃ N ₅ material according to any one of claims 1-5, characterized in that step c is carried out after step a, and step c is: adding the mixed powder into the auxiliary agent solution in, and stir evenly, then dry, and then carry out step b to the dried powder; the auxiliary agent is sodium hydroxide or potassium bromide. 7. The preparation method of C ₃ N ₅ material according to claim 6, characterized in that: the concentration of the auxiliary agent solution is 0.05-0.15g/mL, preferably the concentration of the auxiliary agent solution is 0.1g/mL . 8. The preparation method of C ₃ N ₅ material according to claim 6, characterized in that: the weight ratio of auxiliary agent to 3-amino-1,2,4-triazole is 1:10-20, preferably auxiliary agent The weight ratio to 3-amino-1,2,4-triazole is 1:15. 9. The C ₃ N ₅ material prepared by the method for preparing the C ₃ N ₅ material according to any one of claims 1-8. 10. The application of the C ₃ N ₅ material according to claim 9 in photocatalysts.