CN108584892A - A kind of preparation method and applications of crystalline phase azotized carbon nano particle - Google Patents

Abstract

The invention discloses a preparation method and application of crystalline carbon nitride nanoparticles, belonging to the field of material preparation. Using cyanamide, dicyandiamide, melamine, ammonium thiocyanate, thiourea, urea, etc. as precursors, it is calcined to generate bulk carbon nitride, and then the bulk carbon nitride is mixed with molten salt and calcined to form crystal phase Carbon nitride, after removing the molten salt, is refluxed with an alkali solution to obtain crystalline carbon nitride nanoparticles. The carbon nitride nanoparticle prepared by the invention is a crystalline substance, has a nanoscale particle size, and is uniformly distributed and exists stably in an aqueous solution. The invention has simple process, low cost, meets actual production needs, and has great application potential in the aspects of nanometer materials, solar cells, sensors, biological imaging and thin film device manufacturing.

Description

A kind of preparation method and application of crystalline carbon nitride nanoparticles

technical field

The invention belongs to the field of material preparation, and in particular relates to a preparation method and application of crystalline carbon nitride nanoparticles.

Background technique

Carbon Nitride (Carbon Nitride) has aroused widespread interest as a metal-free, environmentally friendly material. It is used in the photolysis of water to produce hydrogen (Nat. (Adv.Mater. 2009, 21, 1609), organic photosynthesis (J. Am. Chem. Soc. 2010, 132, 16299), and thin-film devices (Angew. Chem. 2015, 127, 6395) solar cells (J. Am. . Chem. Soc., 2014, 136,13486), LEDs (Adv. Opt. Mater., 2015, 3, 913), sensors (Angew. Chem., Int.Ed. 2010, 49, 9706) and Bioimaging (Angew. Chem. 2016, 128, 3736) and other aspects have been extensively studied. However, the carbon nitride prepared by the traditional method has a bulk structure, and there are problems such as large particles, incomplete polymerization, low crystallinity, and difficulty in film formation, which limit the application prospects of carbon nitride materials.

Contents of the invention

The object of the present invention is to provide a method for preparing crystalline carbon nitride nanoparticles and its application against the deficiencies of the prior art. The carbon nitride nano particles prepared in the invention are crystalline substances with nano-scale particle size, uniformly distributed and stably exist in the aqueous solution. The invention has simple process, low cost, meets actual production needs, and has great application potential in the aspects of nanometer materials, solar cells, sensors, bioimaging and thin film device manufacturing.

To achieve the above object, the present invention adopts the following technical solutions:

A method for preparing crystalline carbon nitride nanoparticles: using carbonitride as a precursor, calcining to generate bulk carbon nitride, then mixing the bulk carbon nitride with molten salt and calcining to generate crystalline carbon nitride, After removing the molten salt, the alkaline solution is refluxed to obtain crystalline carbon nitride nanoparticles.

The preparation method of the crystalline carbon nitride nanoparticles, the specific steps are:

(1) Calcining the precursor in an air or nitrogen atmosphere at 400-600°C for 2-6 hours to obtain bulk carbon nitride;

(2) Grinding and mixing the bulk carbon nitride obtained in step (1) with molten salt;

(3) Calcining the mixture obtained in step (2) in an air or nitrogen atmosphere at 500-600°C for 2-6 hours to generate crystalline carbon nitride;

(4) removing molten salt from the crystalline carbon nitride obtained in step (3);

(5) Reflux the solid powder obtained in step (4) in the alkali solution for 6-12 hours, and then remove the alkali solution to obtain crystalline carbon nitride nanoparticles.

The precursor includes one of cyanamide, dipolycyanamide, melamine, ammonium thiocyanate, thiourea and urea.

Described molten salt is lithium chloride or lithium bromide; Or is the mixture of potassium chloride and lithium chloride; Or is the mixture of potassium bromide and lithium bromide; In described molten salt, the mass ratio of potassium salt and lithium salt is :40-50: 40-50.

In step (2), the mass ratio of bulk carbon nitride to molten salt is 1-10:100.

The molten salt removal in step (4) is: ultrasonically disperse the crystalline carbon nitride obtained in step (3) in water, remove the aqueous solution and then dry to obtain solid powder.

A crystalline carbon nitride nanoparticle prepared by the above-mentioned preparation method has a particle size of 2-6nm and an emission spectrum of 440nm.

An application of the crystalline phase carbon nitride nano-particles as described above: used for photocatalytic decomposition of water to produce hydrogen.

Significant advantage of the present invention is:

The carbon nitride particle prepared by the invention is a crystalline substance with a nanometer particle size, and is uniformly distributed and exists stably in an aqueous solution. The whole production process is simple and easy to control, low energy consumption, low cost, meets actual production needs, and has great application potential in nanomaterials, solar cells, sensors, bioimaging and thin film device manufacturing.

Description of drawings

Fig. 1 is the Fourier transform infrared spectrogram of the crystal phase carbon nitride nanoparticle gained in embodiment 1;

Fig. 2 is the Raman spectrogram of the crystalline phase carbon nitride nanoparticle of embodiment 1 gained;

Fig. 3 is the fluorescence emission spectrum of the crystal phase carbon nitride nanoparticle gained in embodiment 2;

Fig. 4 is the transmission electron microscope figure of the crystalline carbon nitride nanoparticle of embodiment 2 gained;

Fig. 5 is the high-resolution transmission electron microscope picture of the crystal phase carbon nitride nanoparticle gained in embodiment 2;

Fig. 6 is a comparison diagram of the activity of the crystalline carbon nitride nanoparticles obtained in Example 2 and the bulk carbon nitride prepared by direct thermal polymerization of melamine.

Detailed ways

Below are several embodiments of the present invention to further illustrate the present invention, but the present invention is not limited thereto.

Example 1

Firstly, 2 g of dipolycyanamide was weighed and placed in an alumina crucible with a lid, and calcined for 2 h in an air atmosphere at a temperature of 400° C. After natural cooling, the sample was taken out and ground into powder to obtain bulk carbon nitride powder. Weigh 0.5g of bulk carbon nitride powder and 20g of molten salt (a mixture of potassium chloride and lithium chloride) to grind evenly, and calcinate at 600°C for 2 hours in a nitrogen atmosphere, and the solid obtained after natural cooling is ultrasonically dispersed in water. Suction filtration and drying to obtain crystalline carbon nitride. Weigh 0.2 g of crystalline carbon nitride, reflux in 100 mL of 0.1 M sodium hydroxide solution for 12 h, and dialyze to remove the supernatant to obtain crystalline carbon nitride nanoparticles.

Example 2

Firstly, 4 g of melamine was weighed and placed in an alumina crucible with a lid, and calcined for 4 h in a nitrogen atmosphere at a temperature of 500° C. After natural cooling, the sample was taken out and ground into powder to obtain bulk carbon nitride powder. Weigh 0.2g of bulk carbon nitride powder and 20g of molten salt (a mixture of potassium bromide and lithium bromide) to grind evenly, calcinate in a nitrogen atmosphere at 500°C for 2h, and the solid obtained after natural cooling is ultrasonically dispersed in water and removed by centrifugation Dry the supernatant to obtain crystalline carbon nitride. Weigh 0.2 g of crystalline carbon nitride, reflux in 100 mL of 0.1 M potassium hydroxide solution for 12 hours, and centrifuge to remove the supernatant to obtain crystalline carbon nitride nanoparticles.

Example 3

Firstly, 20 g of urea was weighed and placed in an alumina crucible with a cover, and calcined for 4 h in an air atmosphere at a temperature of 400° C. After natural cooling, the sample was taken out and ground into powder to obtain bulk carbon nitride powder. Weigh 2g of bulk carbon nitride powder and 20g of molten salt (a mixture of potassium chloride and lithium chloride), grind them evenly, and calcinate them at 600°C for 2 hours in a nitrogen atmosphere. After filtering and drying, crystalline carbon nitride was obtained. Weigh 0.2 g of crystalline carbon nitride, reflux in 100 mL of 0.1 M sodium hydroxide solution for 12 h, and then dialyze to remove the alkali solution to obtain crystalline carbon nitride nanoparticles.

FIG. 1 is a Fourier transform infrared spectrogram of the crystalline carbon nitride photon nanoparticles obtained in Example 1. FIG. The signals in the intervals of 800cm ^-1 and 1000~1700cm ^-1 in the figure correspond to the breathing vibration of the oxazine ring and the stretching vibration of the aromatic CN heterocycle, respectively.

FIG. 2 is the Raman spectrum of the crystalline carbon nitride nanoparticles obtained in Example 1. 1100~1700cm ^-1 in the figure is the asymmetric CN stretching vibration.

Fig. 3 is the fluorescence emission spectrum diagram of the crystalline carbon nitride nanoparticles obtained in Example 2, and its fluorescence emission peak is located near 440nm.

4 is a transmission electron microscope image of the crystalline carbon nitride nanoparticles obtained in Example 2. It can be seen from the figure that the prepared crystalline carbon nitride has a nanoscale particle size, and the particle size is 2-6nm.

5 is a high-resolution transmission electron microscope image of the crystalline carbon nitride nanoparticles obtained in Example 2. Obvious lattice fringes can be seen from the figure, and the spacing of the lattice fringes is 0.36nm, indicating that it is a crystalline substance.

Fig. 6 is a comparison diagram of the activity of the crystalline carbon nitride nanoparticles obtained in Example 2 and the bulk carbon nitride prepared by direct thermal polymerization of melamine. It can be seen from the figure that the hydrogen production rate of crystalline carbon nitride nanoparticles is about 3.5 times higher than that of bulk carbon nitride.

The above is only a preferred embodiment of the present invention, all changes in the type and amount of precursors made according to the patent scope of the present invention, changes in the type, mixing ratio and amount of molten salt, the type and concentration of alkaline solution And the change of consumption, the change of calcination temperature and atmosphere all should belong to the scope of the present invention.

Claims (8)

1. a kind of preparation method of crystalline phase azotized carbon nano particle, it is characterised in that：Using carboritride as presoma, through calcining Body phase carbon nitride is generated, calcining generation crystalline phase carbonitride, passes through again after removing fused salt after then mixing body phase carbon nitride with fused salt Aqueous slkali reflow treatment obtains crystalline phase azotized carbon nano particle.

2. the preparation method of crystalline phase azotized carbon nano particle according to claim 1, it is characterised in that：The specific steps are：

（1）By presoma under air or nitrogen atmosphere, 400-600 DEG C of calcining 2-6h, body phase carbon nitride is obtained；

（2）By step（1）Obtained body phase carbon nitride and fused salt ground and mixed is uniform；

（3）By step（2）Obtained mixture generates crystalline phase nitridation under air or nitrogen atmosphere, 500-600 DEG C of calcining 2-6h Carbon；

（4）By step（3）Obtained crystalline phase carbonitride removes fused salt；

（5）By step（4）Obtained solid powder is flowed back in aqueous slkali after 6-12h, is removed aqueous slkali, is obtained crystalline phase carbonitride Nano particle.

3. the preparation method of crystalline phase azotized carbon nano particle according to claim 1 or 2, it is characterised in that：Before described It includes one kind in cyanamide, cyanamid dimerization, melamine, thiocyanic acid amine, thiocarbamide, urea to drive body.

4. the preparation method of crystalline phase azotized carbon nano particle according to claim 1 or 2, it is characterised in that：Described is molten Salt is lithium chloride or lithium bromide；Or the mixture for potassium chloride and lithium chloride；Or the mixing for potassium bromide and lithium bromide Object.

5. the preparation method of crystalline phase azotized carbon nano particle according to claim 2, it is characterised in that：Step（2）Middle body The mass ratio of phase carbon nitride and fused salt is：1-10:100.

6. the preparation method of crystalline phase azotized carbon nano particle according to claim 2, it is characterised in that：Step（4）It is described Removing fused salt be：By step（3）Obtained crystalline phase carbonitride ultrasonic disperse in water is dried after removing aqueous solution, consolidate Body powder.

7. crystalline phase azotized carbon nano particle made from a kind of preparation method as claimed in claim 1 or 2, it is characterised in that：It is brilliant The grain size of phase carbon nitride nano particle is in 2 ~ 6nm, and emission spectrum is in 440nm.

8. a kind of application of crystalline phase azotized carbon nano particle as claimed in claim 7, it is characterised in that：For photocatalysis Decomposition Water hydrogen making.