A honeycomb-like tremella-like structure morphology photocatalyst and a preparation method thereof

Abstract

The application discloses a honeycomb-like tremella-like structure morphology photocatalyst and a preparation method thereof. On the basis of preparing graphite phase carbon nitride by a pyrolysis method, the carbon nitride is introduced into the preparation process of a bismuth silicate heterostructure to modify the hetero-bismuth silicate. The carbon nitride is used to form a porous plate structure on the bismuth silicate nanosheet and simultaneously induce the growth of the bismuth silicate nanosheet. The originally stacked nanosheets are peeled off from each other and then self-assembled to form a flower-like tremella-like structure, so as to prepare a honeycomb-like tremella-like structure morphology sheet stack photocatalyst. The method has the advantages of simple process, short cycle, simple equipment and low cost. The obtained composite material has good powder dispersity and high photocatalytic performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photocatalysts, and particularly relates to a honeycomb-like tremella-like structure morphology photocatalyst and a preparation method thereof. BACKGROUND

[0002] In recent years, water pollution has become an important problem of global environmental pollution, which has seriously threatened human health and social development. In the aspect of water pollution treatment, photocatalytic technology can utilize solar energy to degrade pollutants in dye wastewater into inorganic small molecules to solve the problem of water pollution, so the technology has been widely concerned. Bismuth silicate has good dielectricity, thermoelectricity and nonlinear opticality, and is expected to become a high-efficiency photocatalyst, but its hydrophobicity and low surface area greatly limit the practical application, so it is particularly important to reasonably modify it from the surface properties and morphology. At present, whether it is a single-component photocatalyst or a composite heterojunction catalyst material, the morphology is mostly in the form of thick sheet accumulation, the surface area cannot be limited, and the active sites cannot be effectively exposed, which further limits the degradation efficiency of pollutants. SUMMARY

[0003] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a honeycomb-like tremella-like structure morphology photocatalyst and a preparation method thereof, which has the advantages of simple process, simple equipment requirement, good dispersibility of the prepared material, uniform particle size distribution of the obtained composite photocatalyst, smaller and thinner sheet structure, more active sites, which can effectively improve the light utilization rate and improve the photocatalytic activity.

[0004] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0005] A preparation method of a honeycomb-like tremella-like structure morphology photocatalyst, comprising the following steps:

[0006] Step 1: mixing Bi(NO3)3·5H2O, ethylene glycol and deionized water to prepare A liquid; mixing Na2SiO3·9H2O and deionized water to prepare B liquid, slowly adding B liquid into A liquid to obtain bismuth silicate hydrothermal precursor;

[0007] Step 2: preparing carbon nitride;

[0008] Step 3: adding the carbon nitride into the bismuth silicate hydrothermal precursor, uniformly dispersing, then transferring into a polytetrafluoroethylene inner liner and placing into a hydrothermal kettle for hydrothermal reaction, after reaction, cooling to room temperature, washing with deionized water and anhydrous ethanol alternately, drying, grinding and calcining to obtain carbon nitride-heterogeneous bismuth silicate heterojunction photocatalyst, i.e. the honeycomb-like tremella-like structure morphology photocatalyst.

[0009] In one embodiment, the mass concentration of Bi(NO3)3·5H2O in the A liquid is 60% to 80%, and the mass concentration of Na2SiO3·9H2O in the B liquid is 20% to 50%. The molar concentration of the AB liquid is controlled to be 0.3 mol / L to 1.2 mol / L.

[0010] In one embodiment, the amount of Bi(NO3)3·5H2O in the A liquid is 0.001 mol to 0.01 mol, and the amount of ethylene glycol is 5 mL to 10 mL, and the mixture is stirred for 10 min to 40 min; the amount of Na2SiO3·9H2O in the B liquid is 0.001 mol to 0.01 mol, and the amount of deionized water is 5 mL to 10 mL, and the stirring time is 10 min to 40 min; the B liquid is slowly added into the A liquid, and stirred for 10 min to 20 min to obtain a bismuth silicate hydrothermal precursor, and the amount of carbon nitride added in the step 3 is 0.1 g to 0.3 g.

[0011] In one embodiment, in the step 2, the urea is placed in a crucible, sealed and placed in a muffle furnace, and calcined at a temperature of 500 ℃ to 700 ℃ under an air atmosphere at a temperature increasing rate of 10 ℃ / min to 20 ℃ / min for 2 h to 5 h to obtain a bulk carbon nitride.

[0012] In one embodiment, in the step 3, the carbon nitride is added into the bismuth silicate hydrothermal precursor, stirred for 10 min to 30 min, then placed in an ultrasonic cleaner for ultrasonic treatment for 10 min to 30 min, and then continuously stirred until uniformly dispersed, and the drying condition is 60 ℃ for 8 h to 10 h.

[0013] In one embodiment, the filling ratio in the hydrothermal kettle is 40% to 70%.

[0014] In one embodiment, the hydrothermal reaction condition is 100 ℃ to 200 ℃ for 8 h to 10 h, and the calcination is carried out in a muffle furnace at a temperature of 300 ℃ to 500 ℃ for 1 h to 5 h.

[0015] The application also claims protection to a honeycomb-like tremella-like structure morphology photocatalyst prepared by the above preparation method. The honeycomb-like tremella-like structure morphology photocatalyst can be used for degrading organic dyes, antibiotics and the like.

[0016] Compared with the prior art, the application has the following beneficial effects:

[0017] 1. Bismuth silicate is a new type of semiconductor photocatalyst, which has good dielectric property, piezoelectricity, non-toxicity, chemical stability and the like, and is a high-efficiency photocatalyst due to its unique two-dimensional layered structure and electronic configuration.

[0018] 2, the introduction of carbon nitride induces the growth of bismuth silicate to change the micro-morphology: during the growth of bismuth source and silicon source at high temperature, bismuth silicate often grows in a specific direction, resulting in thick layers and large size. The introduction of carbon nitride into the reaction process can destroy the preferred growth of bismuth silicate, effectively increase the nucleation site, and guide the crystal growth on the surface of the crystal nucleus. The process controls the crystal morphology, and the nucleation rate is greater than the crystal growth rate, so that the original stacked nanosheets are peeled off and self-assembled to form a tremella-like structure. After further heat treatment, the high temperature makes part of the C-N bond break, and the carbon nitride escapes, so that the tremella-like structure is distorted and a large number of pores are generated, forming a porous plate structure on the nanosheet, which is beneficial to the attachment of pollutants, thereby obtaining a honeycomb-like tremella structure photocatalyst.

[0019] 3, the modified bismuth silicate photocatalyst introduced by carbon nitride is easy to form a porous structure, i.e. a honeycomb-like tremella structure, and the gap distance between the pores is small, which can further promote the combination between carbon nitride and bismuth silicate, thereby more efficiently forming a heterojunction, avoiding the invalid heterostructure between thick sheet morphology, reducing the recombination rate of photo-generated electrons and holes while improving the utilization rate of sunlight. In the photocatalytic process, the electrons on the conduction band are excited to form photo-generated electrons and holes. h + and·O 2- is converted into free radicals that are beneficial to the catalytic reaction, further improving the photocatalytic performance of the composite.

[0020] 4, the preparation process of the present application is simple, the prepared powder has uniform particle size distribution and light agglomeration, the synergistic effect of the heterojunction interface and the honeycomb-like tremella structure enhances the photocatalytic activity, the prepared powder has good dispersibility and good ability to degrade organic dyes and part of antibiotics. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a SEM image of a honeycomb-like tremella structure photocatalyst.

[0022] Figure 2 is a photocatalytic degradation curve of a honeycomb-like tremella structure photocatalyst for degrading rhodamine B. DETAILED DESCRIPTION

[0023] The embodiments of the present application will be described in detail below with reference to the drawings and examples. The technical solutions of the present application are not limited to the specific embodiments listed below, but also include any combination of the specific embodiments.

[0024] A honeycomb-like tremella structure photocatalyst and a preparation method thereof, which is a modified bismuth silicate hetero-photocatalytic material prepared by using carbon nitride as a template, specifically comprising the following steps:

[0025] Step 1, dissolve 0.001 mol-0.01 mol of Bi (NO3) 3·5H2O in 5 mL-10 mL of a mixed solution of ethylene glycol and deionized water, stir for 10 min-40 min to obtain solution A; dissolve 0.001 mol-0.01 mol of Na2SiO3·9H2O in 5 mL-10 mL of deionized water, stir for 10 min-40 min to obtain solution B. Slowly add solution B into solution A and stir for 10 min-20 min to obtain a bismuth silicate hydrothermal precursor.

[0026] Step 2, place urea in a crucible, seal it in a muffle furnace, and heat it to 500℃-700℃ at a heating rate of 10℃ / min-20℃ / min under air atmosphere for 2h-5h to obtain bulk carbon nitride. This step realizes the pyrogenic preparation of graphite phase carbon nitride.

[0027] Step 3, take a small amount of carbon nitride powder and add it to the bismuth silicate hydrothermal precursor, stir for 10 min-30 min, then place it in an ultrasonic cleaner and ultrasonic for 10 min-30 min, continue to stir until it is evenly dispersed, then transfer it to a polytetrafluoroethylene liner and place it in a hydrothermal kettle, hydrothermal reaction at 100℃-200℃ for 8h-10h. After the reaction, cool it to room temperature, wash it with deionized water and anhydrous ethanol alternately, dry it at 60℃ for 8h-10h, grind it, and calcine it in a muffle furnace at 300℃-500℃ for 1h-5h to obtain a carbon nitride-heterogeneous bismuth silicate heterogeneous photocatalytic material.

[0028] This step introduces graphite phase carbon nitride into the preparation process of bismuth silicate heterostructure to modify the heterogeneous bismuth silicate. The carbon nitride forms a porous plate structure on the bismuth silicate nanosheet and induces its growth, causing the originally stacked nanosheets to peel off each other and then self-assemble into a flower-like agaric structure, thereby preparing a honeycomb-like agaric structure morphology sheet layer stacking photocatalyst. The introduction of carbon nitride into bismuth silicate for compounding and regulation, on the one hand, a spatial potential difference will be formed between the energy band structure of carbon nitride and bismuth silicate, thereby better transferring photo-generated carriers and further inhibiting the recombination of photo-generated electrons and holes, on the other hand, the introduction of carbon nitride forms a porous structure on the bismuth silicate nanosheet and induces its mutual peeling and regrowth, thereby forming a honeycomb-like agaric morphology, exposing more active sites and improving the photocatalytic performance of the material. This method is simple in process, short in cycle, simple in equipment, and low in cost. The obtained composite material has good powder dispersity and exhibits high photocatalytic performance.

[0029] The following are several embodiments of the present application.

[0030] Example 1

[0031] (1) 0.005 mol of Bi(NO3)3·5H2O was dissolved in 7 mL of a mixed solution of ethylene glycol and deionized water, and stirred for 20 min to obtain solution A; 0.005 mol of Na2SiO3·9H2O was dissolved in 7 mL of deionized water, and stirred for 20 min to obtain solution B. Solution B was slowly added to solution A, and stirred for 20 min to obtain a bismuth silicate hydrothermal precursor.

[0032] (2) Urea was placed in a crucible, sealed, and placed in a muffle furnace, and calcined at 600℃ for 3 h at a heating rate of 15℃ / min under air atmosphere to obtain bulk carbon nitride.

[0033] (3) A small amount (about 0.3 g) of carbon nitride powder was added to the bismuth silicate hydrothermal precursor, stirred for 10 min, then placed in an ultrasonic cleaner for 10 min, and continued to be stirred until uniformly dispersed. Then it was transferred to a polytetrafluoroethylene liner, and placed in a hydrothermal kettle, and hydrothermally reacted at 120℃ for 8 h. After the reaction, it was cooled to room temperature, washed with deionized water and anhydrous ethanol alternately, dried at 60℃ for 8 h, ground, and calcined in a muffle furnace at 350℃ for 2 h to obtain carbon nitride-heterogeneous bismuth silicate heterogeneous photocatalytic material.

[0034] Figure 1 Figure is a SEM image of the catalyst obtained in this example, and it can be seen that the obvious sheet structure is attached to the porous carbon nitride nanosheet, and the two are closely combined. The diameter of the holes in the honeycomb-like nanosheet is 0.2 nm-0.5 nm, and the sheet layer grows outward on the nanosheet, the sheets are peeled off from each other, and are stacked together to form a silver ear-like structure, and the assembly form is very compact, with a diameter of 2 μm-3 μm. The silver ear-like structure provides more active sites, which can improve the photocatalytic performance.

[0035] In the process of industrial production, a lot of industrial wastewater may be produced, which includes many organic dyes, and in some cases, antibiotic residues may also exist. The photocatalyst prepared under the preparation conditions of the present application can degrade the pollutants in the industrial pollution wastewater, and reduce the pollution to the environment.

[0036] Figure 2 Figure is the photocatalytic degradation curve of the catalyst obtained in this example in a solution containing organic dye rhodamine B and degrading the same. In the experiment, 30 mL of rhodamine B was taken, with a concentration of 10 mg / L, and 3 mg of catalyst was added. After the addition, the photocatalytic reaction was carried out for 150 min, including 60 min of dark reaction and 90 min of light reaction. It can be seen that under the condition of light for 90 min, the degradation rate is as high as 99.8%. Combined with the SEM image, this is due to the porous structure after calcination, which exposes more active sites, and realizes higher catalytic degradation effect.

[0037] Example 2

[0038] (1) 0.007 mol of Bi(NO3)3·5H2O was dissolved in 9 mL of a mixed solution of ethylene glycol and deionized water, and stirred for 20 min to obtain solution A; 0.007 mol of Na2SiO3·9H2O was dissolved in 9 mL of deionized water, and stirred for 20 min to obtain solution B. Solution B was slowly added to solution A, and stirred for 15 min to obtain a bismuth silicate hydrothermal precursor.

[0039] (2) Urea was placed in a crucible, sealed, and placed in a muffle furnace, and calcined at 550℃ at a heating rate of 15℃ / min under an air atmosphere for 2 h to obtain bulk carbon nitride.

[0040] (3) A small amount (about 0.5 g) of carbon nitride powder was added to the bismuth silicate hydrothermal precursor, stirred for 15 min, then placed in an ultrasonic cleaner and ultrasonically cleaned for 15 min, and then continuously stirred until uniformly dispersed. Then, it was transferred to a polytetrafluoroethylene liner, and placed in a hydrothermal kettle, and hydrothermally reacted at 150℃ for 10 h. After the reaction, it was cooled to room temperature, washed with deionized water and anhydrous ethanol alternately, dried at 60℃ for 8 h, ground, and calcined in a muffle furnace at 400℃ for 3 h to obtain carbon nitride-hetero bismuth silicate hetero photocatalytic material.

[0041] In more embodiments of the present application, the aforementioned parameters were combined in different types, for example, in step 1), Bi(NO3)3·5H2O was selected at 0.001 mol, 0.005 mol, and 0.01 mol, respectively, ethylene glycol was selected at 5 mL, 8 mL, and 10 mL, respectively, and Na2SiO3·9H2O was selected at 0.001 mol, 0.005 mol, and 0.01 mol, respectively. The results proved that bismuth silicate hydrothermal precursors could be prepared.

[0042] Similarly, in step 2), the heating rate was selected at 10℃ / min, 15℃ / min, and 20℃ / min, the holding temperature was selected at 500℃, 600℃, and 700℃, and the holding time was selected at 2 h, 4 h, and 5 h. The results proved that bulk carbon nitride could be prepared.

[0043] Similarly, in step 3), during the hydrothermal reaction, the temperature was selected at 100℃, 150℃, and 200℃, and the time was selected at 8 h, 9 h, and 10 h. The results proved that carbon nitride-hetero bismuth silicate hetero photocatalytic material could be prepared.

[0044] The above embodiments are preferred embodiments of the present application, but the embodiments of the present application are not limited by the above embodiments, and any changes, substitutions, combinations, simplifications, etc. made on the basis of the principles or spirit of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for preparing a honeycomb-tremella-like structure morphology photocatalyst, characterized in that, It comprises the following steps: Step 1, Bi(NO3)3·5H2O, ethylene glycol and deionized water are mixed to prepare A liquid; Na2SiO3·9H2O and deionized water are mixed to prepare B liquid, and B liquid is slowly added into A liquid to obtain bismuth silicate hydrothermal precursor; the amount of Bi(NO3)3·5H2O in the A liquid is 0.001 mol~0.01 mol, and the amount of ethylene glycol is 5 mL~10 mL, and the mixture is stirred for 10 min~40 min; the amount of Na2SiO3·9H2O in the B liquid is 0.001 mol~0.01 mol, and the amount of deionized water is 5 mL~10 mL, and the mixture is stirred for 10 min~40 min; B liquid is slowly added into A liquid and stirred for 10 min~20 min to obtain bismuth silicate hydrothermal precursor; Step 2, prepare carbon nitride; Step 3, the amount of carbon nitride added into the bismuth silicate hydrothermal precursor is 0.1 g~0.3 g, and the carbon nitride is uniformly dispersed, and then transferred into a polytetrafluoroethylene liner and placed in a hydrothermal kettle for hydrothermal reaction under the condition of 100℃~200℃ for 8 h~10 h, and after reaction, cooled to room temperature, washed with deionized water and anhydrous ethanol alternately, dried, ground and calcined to obtain carbon nitride-heterogeneous bismuth silicate heterogeneous photocatalytic material, i.e. the honeycomb-like tremella-like structure morphology photocatalyst.

2. The method for preparing the honeycomb-like tremella-like structure morphology photocatalyst according to claim 1, characterized in that, In step 1, the mass concentration of Bi(NO3)3·5H2O in A liquid is 60%~80%, and the mass concentration of Na2SiO3·9H2O in B liquid is 20%~50%.

3. The method for preparing the honeycomb-shaped, silver ear-like structure photocatalyst according to claim 1, characterized in that, In step 2, the urea is placed in a crucible, sealed and placed in a muffle furnace, and calcined at a temperature of 500℃~700℃ under air atmosphere at a heating rate of 10℃ / min~20℃ / min for 2 h~5 h to obtain bulk carbon nitride.

4. The method of claim 1, wherein the method comprises the steps of: (a) mixing the silver salt with the reducing agent; (b) adding the base to the mixture; (c) adding the surfactant to the mixture; (d) adding the solvent to the mixture; and (e) stirring the mixture until the desired morphology is obtained. In step 3, the carbon nitride is added into the bismuth silicate hydrothermal precursor, stirred for 10 min~30 min, then ultrasonically cleaned for 10 min~30 min, and then continuously stirred until uniformly dispersed, and the drying condition is 60℃ for 8 h~10 h.

5. The method of claim 1, wherein the method comprises the steps of: (a) mixing the silver salt with the reducing agent; (b) adding the base to the mixture; (c) adding the surfactant to the mixture; (d) adding the solvent to the mixture; and (e) stirring the mixture until the desired morphology is obtained. The filling ratio in the hydrothermal kettle is 40%~70%.

6. The method of claim 1, wherein the method comprises the steps of: (a) mixing the silver salt with the reducing agent; (b) adding the base to the mixture; (c) adding the surfactant to the mixture; (d) adding the solvent to the mixture; and (e) stirring the mixture until the desired morphology is obtained. The calcination is carried out in a muffle furnace at a temperature of 300℃~500℃ for 1 h~5 h.

7. The honeycomb-like tremella-like structure morphology photocatalyst prepared by the preparation method of any one of claims 1 to 6.

8. The application of the honeycomb-like tremella-like structure morphology photocatalyst of claim 7 for degrading organic dyes.

9. The application of the honeycomb-like tremella-like structure morphology photocatalyst of claim 7 for degrading antibiotics.

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