Hollow porous carbon nitride nanospheres composite loaded with AgBr nanoparticles, preparation method thereof, and its application in dye degradation

Abstract

A hollow porous carbon nitride nanospheres composite loaded with AgBr nanoparticles, preparation method thereof, and its application in dye degradation are disclosed. Using silica nanosphere with core-shell structure as a template and hydrogen cyanamide as precursor, melting to enter the pores of mesoporous silica, after calcination, the silica template is etched with ammonium bifluoride to obtain hollow porous carbon nitride nanospheres; dispersing hollow porous carbon nitride nanospheres in deionized water, adding silver nitrate and sodium bromide in sequence, and obtaining silver bromide nanoparticles by in-situ ion exchange method, stirring, washing and centrifuging to obtain the hollow porous carbon nitride nanospheres composite. The hollow porous carbon nitride prepared by the template method has good photocatalytic effect on dye degradation after composite with silver bromide; and it has the advantages of easy production of raw materials, good stability, reusability, etc. It has application prospects in the treatment of dyes.

Claims

1. A preparation method of hollow porous carbon nitride nanospheres composite loaded with AgBr nanoparticles, comprising the following steps: (1) using silica nanosphere with core-shell structure as a template and hydrogen cyanamide as precursor to prepare hollow porous carbon nitride nanospheres after reaction, calcination and template removal; (2) dispersing said hollow porous carbon nitride nanospheres in deionized water, adding silver nitrate and sodium bromide in sequence, to obtain hollow porous carbon nitride nanospheres composite loaded with AgBr nanoparticles, wherein in step (2), in the hollow porous carbon nitride nanospheres composite loaded with AgBr nanoparticles, the mass ratio of hollow porous carbon nitride to silver bromide is 5:3; the reaction is carried out in the dark, and the reaction time is 4 hours.

2. The preparation method of hollow porous carbon nitride nanospheres composite loaded with AgBr nanoparticles according to claim 1, wherein in step (1), the mass ratio of silica to hydrogen cyanamide is 1:5; the temperature of the reaction is 60 C., and the time is 24 h; said calcination is carried out under argon protection, and the heating rate is 5 C./min during calcining, the calcination time is 4 h, the calcination temperature is 550 C.; the template is etched using ammonium bifluoride; the etching time is 12 h.

3. The preparation method of hollow porous carbon nitride nanospheres composite loaded with AgBr nanoparticles according to claim 1, wherein in step (1), mixing water, ammonia water, ethanol, then adding tetraethyl orthosilicate, stirring to obtain a silica core solution; adding a mixture of tetraethyl orthosilicate and tetramethoxysilane dropwise, after standing; and then centrifugation, washing, drying, and calcination to obtain silica nanosphere with core-shell structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1. TEM images of the silica after calcination at 550 C.

(2) FIG. 2. SEM images of the hollow porous carbon nitride nanospheres after calcination at 550 C.

(3) FIG. 3. TEM images of the hollow porous carbon nitride nanospheres after calcination at 550 C.

(4) FIG. 4. SEM images of AgBr nanoparticles loaded on the surface of hollow porous carbon nitride nanospheres.

(5) FIG. 5. TEM images of AgBr nanoparticles loaded on the surface of hollow porous carbon nitride nanospheres.

(6) FIG. 6. Catalytic effect diagram of hollow porous carbon nitride nanospheres with different loadings of silver bromide nanoparticles.

(7) FIG. 7. Catalytic cycle diagram of hollow porous carbon nitride nanospheres loaded with silver bromide nanoparticles.

DETAILED DESCRIPTION OF THE INVENTION

(8) Implementation 1

(9) Synthesis of the SiO.sub.2 with Core-Shell Structure, Comprising the Following Steps:

(10) 10 mL ultrapure water and 3.5 g aqueous ammonia were added into round-bottom flask including 58.5 g ethanol solution. After stirring for 30 min at 30 C., 5.6 mL TEOS was added into the above-prepared mixture quickly and the mixture kept stirring for 1 h to yield uniform silica spheres. To create a mesoporous silica shell, a mixture solution containing 5.83 g TEOS and 2.62 g C.sub.18 TMOS was added into above solution drop by drop. Then, the mixed solution was kept static for 1 h. The resulting reaction solution was centrifuged, washed, dried, then calcined at 550 C. for 6 h. Washed with a 1-M HCl solution, washed with ethanol and dried at 80 C.

(11) Implementation 2

(12) Synthesis of Hollow Porous Carbon Nitride Nanospheres (HCNS), Comprising the Following Steps:

(13) 1 g SiO.sub.2 powder and 5 g thawy cyanamide were fully mixed, reacting for 1 h at 60 C. Then treating by ultrasonic treatment for 4 h, reacting at 60 C. for one night. The resultant was centrifuged and dried in air to obtain a white powder that was put into a crucible to calcine under flowing Ar to obtain HCNS, raising the temperature to 550 C. with a heating rate of 4.4 C./min, calcining for 4 h. By calcination, the present invention obtains HCNS having a large specific surface area.

(14) FIG. 1 showed the TEM images of silica with core-shell structure. FIG. 2 showed the SEM images of hollow porous carbon nitride nanospheres. FIG. 3 showed the TEM images of HCNS, the hollow sphere structure can be seen from the figure, and the distribution is more uniform.

(15) Implementation 3

(16) Loading AgBr Nanoparticles onto the Surface of Hollow Porous Carbon Nitride Nanospheres, Comprising the Following Steps:

(17) A given amount of HCNS (obtained in Implementation 2) was dispersed in 8 mL deionized water, and the suspension was sonicated for 30 min. Then, 85 mg AgNO.sub.3 was added into above suspension and stirred for 1 h in the dark. Then, 51.5 mg NaBr was dissolved in 5 mL water and added dropwise into the above mixture, which was stirred for 3 h in the dark. The resulting products were centrifuged and washed and dried at 60 C. for one night, to obtain hollow porous carbon nitride nanospheres loaded with AgBr nanoparticles, noted as HCNS/AgBr. Different mass ratios composite materials were obtain according to the different mass of hollow porous carbon nitride nanospheres added, and noted as HCNS/AgBr10, HCNS/AgBr30, HCNS/AgBr60, HCNS/AgBr90.

(18) FIG. 4 showed the SEM images of AgBr nanoparticles loaded on the surface of hollow porous carbon nitride nanospheres. FIG. 5 showed the TEM images of AgBr nanoparticles loaded on the surface of hollow porous carbon nitride nanospheres. It can be seen from the figure that the silver bromide has a smaller particle size and a more uniform distribution.

(19) Implementation 4

(20) Photocatalytic Activity, Comprising the Following Steps:

(21) 0.1 g photocatalysts, hollow porous carbon nitride nanospheres composite loaded with AgBr nanoparticles, were put into 100 mL OG (25 ppm) in a reactor. Stir for 30 min at in the dark to get adsorption equilibrium. Degradation by 300 W xenon lamp, sampling 3 mL at certain time intervals, obtaining centrifugation solution for UV-vis spectroscopy analysis.

(22) FIG. 6 shows the effect of degradation of acid orange G with different mass ratios; FIG. 7 shows a cycle diagram of the number of catalyst (HCNS/AgBr60).