CN114984993B - N, S quantum dot/bismuth tungstate composite photocatalyst, and preparation method and application thereof - Google Patents

Abstract

The invention discloses an N, S quantum dot/bismuth tungstate composite photocatalyst, a preparation method and application thereof, and belongs to the technical field of photocatalytic materials. Coral Bi is mixed according to the dosage ratio of 80-120 mg to 10-100 mg to 20-30 ml ₂ WO ₆ And dissolving the N and S quantum dots in methanol, carrying out ultrasonic treatment for 60-80 min, stirring and heating until the sample is completely dried, and obtaining the N and S quantum dot/bismuth tungstate composite photocatalyst. According to the invention, the N, S quantum dots are loaded on the bulk bismuth tungstate, and the prepared N, S quantum dot/bismuth tungstate composite photocatalyst has the advantages of stable structure, high catalytic activity and high repeatability, and can meet the requirements of laboratories and industries. The photocatalytic degradation performance of the material can be obviously improved, and a new scheme is provided for solving the environmental pollution.

Description

An N,S quantum dot/bismuth tungstate composite photocatalyst and its preparation method and application

Technical field

The invention belongs to the technical field of photocatalytic materials, and specifically relates to an N,S quantum dot/bismuth tungstate composite photocatalyst and its preparation method and application.

Background technique

With the development of economy, two major problems, energy crisis and environmental pollution, have seriously affected people's production and life. How to alleviate the energy crisis and protect the deteriorating environment has attracted the attention of many researchers. Currently, photocatalytic technology is considered to be one of the most promising methods to solve the above problems. As a green, economical and efficient technology, photocatalytic technology can directly convert solar energy into chemical energy to achieve photocatalytic degradation of organic/inorganic pollutants, photocatalytic water splitting to generate _H2 and photocatalytic organic synthesis.

Contents of the invention

In view of the above-mentioned problems existing in the prior art, the first technical problem to be solved by the present invention is to provide an N,S quantum dot/bismuth tungstate composite photocatalyst; the second technical problem to be solved by the present invention is to provide N,S quantum dots. Preparation method of dot/bismuth tungstate composite photocatalyst; the third technical problem to be solved by the present invention is to provide the application of N,S quantum dot/bismuth tungstate composite photocatalyst.

In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

An N,S quantum dot/bismuth tungstate composite photocatalyst is loaded with N,S quantum dots on bismuth tungstate.

The preparation method is as follows: dissolve coral-like Bi ₂ WO ₆ and N,S quantum dots in methanol, stir and heat until completely dry, to obtain N,S quantum dots/bismuth tungstate composite photocatalyst.

Further, the dosage ratio of coral-like Bi ₂ WO ₆ , N,S quantum dots and methanol is 80 to 120 mg: 10 mg to 100 mg: 20 to 30 ml.

Specifically: dissolve coral-like Bi ₂ WO ₆ and N, S quantum dots in methanol according to the dosage ratio, ultrasonic for 60 to 80 minutes, then stir and heat until the sample is completely dry to obtain N, S quantum dots/bismuth tungstate composite photocatalyst .

Among them, the preparation method of N, S quantum dots is: mix citric acid monohydrate, cysteamine hydrochloride and water according to the dosage ratio of 7 to 12mmol: 5 to 10mmol: 5 to 10m1, and stir for 10 to 20 minutes until completely dissolved. After reacting at 60-80°C for 24-48 hours, transfer the liquid to a high-pressure reactor and react at 180-250°C for 2-4 hours; after cooling to room temperature, wash and freeze-dry to obtain brown powder, namely N, S quantum dots.

The preparation method of coral-like Bi ₂ WO ₆ is:

S1. Dissolve Bi(NO ₃ ) ₃ ·5H ₂ O and Na ₂ WO ₄ ·2H ₂ O in water respectively to obtain solution A and solution B; add solution B to A drop by drop, and continue stirring for 24 to 48 hours. Wash and dry to obtain Bi ₂ WO ₆ precursor;

Further, the dosage ratio of Bi(NO ₃ ) ₃ ·5H ₂ O and water is 10～30mmol:20～40ml; the dosage ratio of Na ₂ WO ₄ ·2H ₂ O and water is 5～25mmol:10～30ml; solution A contains concentrated nitric acid solution, and the volume ratio of concentrated nitric acid solution to water is 3~8ml:20~40ml;

S2. Mix Bi ₂ WO ₆ precursor and NaNO ₃ -KNO ₃ mixed salt at a mass ratio of 1:3 to 1:7, and grind evenly; put the mixture into a muffle furnace and calcine at 300 to 450°C 3 ~6h; finally, the product is repeatedly washed with distilled water and dried at 60~80°C for 12~24h to obtain coral-like Bi ₂ WO ₆ .

Application of the N,S quantum dot/bismuth tungstate composite photocatalyst in environmental photocatalysis.

Compared with the existing technology, the beneficial effects of the present invention are:

(1) The N,S quantum dot/bismuth tungstate composite photocatalyst prepared by the present invention has a stable structure, high catalytic activity and high repeatability, and can meet laboratory and industrial needs.

(2) By loading N, S quantum dots on bulk bismuth tungstate, the present invention can significantly improve the photocatalytic degradation performance of the material.

Description of the drawings

Figure 1 is the XRD pattern of the N,S quantum dot/bismuth tungstate composite photocatalyst prepared in Example 2;

Figure 2 is a UV-vis DRS diagram of the N,S quantum dot/bismuth tungstate composite photocatalyst prepared in Example 2;

Figure 3 is a photocatalytic degradation performance diagram of the N,S quantum dot/bismuth tungstate composite photocatalyst prepared in the present invention;

Figure 4 is a degradation cycle stability chart of the N,S quantum dot/bismuth tungstate composite photocatalyst prepared in Example 2.

Detailed ways

The present invention will be further described below with reference to specific embodiments. These examples are only used to illustrate the invention and are not intended to limit the scope of the invention. Without departing from the spirit and essence of the present invention, any modifications or substitutions made to the method, steps or conditions of the present invention shall fall within the scope of the present invention. Unless otherwise specified in the following examples, the technical means used in the examples are conventional means well known to those skilled in the art.

Example 1

A preparation method of N,S quantum dots/bismuth tungstate composite photocatalyst, including the following steps:

(1) Dissolve 9.5mmol citric acid monohydrate and 8.8mmol cysteamine hydrochloride in 8ml distilled water, stir for 10min until completely dissolved, react at 80°C for 24h, then transfer the liquid to a polytetrafluoroethylene-lined stainless steel high-pressure In the kettle, react at 200°C for 3.5 hours; after cooling to room temperature, wash and freeze-dry to obtain brown powder, namely N,S quantum dots.

(2) Dissolve 20mmolBi(NO ₃ ) ₃ ·5H ₂ O in 20ml distilled water, add 5ml concentrated nitric acid solution, and obtain solution A; dissolve 10mmolNa ₂ WO ₄ ·2H ₂ O in 10ml distilled water, and obtain solution B under magnetic stirring. , add solution B dropwise to solution A, continue stirring for 24 hours, then wash and dry to obtain the Bi ₂ WO ₆ precursor;

(3) Mix the Bi ₂ WO ₆ precursor and the NaNO ₃ -KNO ₃ mixed salt at a mass ratio of 1:5 and grind them evenly; put the mixture into a muffle furnace and calcine at 350°C for 4 hours; finally, wash the product repeatedly with distilled water , dried at 80°C for 12 hours to obtain coral-like Bi ₂ WO ₆ .

(4) Dissolve 100 mg of Bi ₂ WO ₆ and 10 mg of N, S quantum dots in 20 ml of methanol; ultrasonic for 60 minutes, then stir and heat until the sample is completely dry to obtain the N, S quantum dots/bismuth tungstate composite photocatalyst, recorded is N, S/BW-0.1.

Example 2

A preparation method of N,S quantum dots/bismuth tungstate composite photocatalyst, including the following steps:

(1) Dissolve 9.5mmol citric acid monohydrate and 8.8mmol cysteamine hydrochloride in 8ml distilled water, stir for 10min until completely dissolved, react at 80°C for 24h, then transfer the liquid to a polytetrafluoroethylene-lined stainless steel high-pressure In the kettle, react at 200°C for 3.5 hours; after cooling to room temperature, wash and freeze-dry to obtain brown powder, namely N and S quantum dots.

(2) Dissolve 20mmolBi(NO ₃ ) ₃ ·5H ₂ O in 20ml distilled water, add 5ml concentrated nitric acid solution, and obtain solution A; dissolve 10mmolNa ₂ WO ₄ ·2H ₂ O in 10ml distilled water, and obtain solution B under magnetic stirring. , add solution B dropwise to solution A, continue stirring for 24 hours, then wash and dry to obtain the Bi ₂ WO ₆ precursor;

(3) Mix the Bi ₂ WO ₆ precursor and the NaNO ₃ -KNO ₃ mixed salt at a mass ratio of 1:5 and grind them evenly; put the mixture into a muffle furnace and calcine at 350°C for 4 hours; finally, wash the product repeatedly with distilled water , dried at 80°C for 12 hours to obtain coral-like Bi ₂ WO ₆ .

(4) Dissolve 100 mg of Bi ₂ WO ₆ and 20 mg of N, S quantum dots in 20 ml of methanol; ultrasonic for 60 minutes, then stir and heat until the sample is completely dry to obtain the N, S quantum dots/bismuth tungstate composite photocatalyst, recorded is N, S/BW-0.2.

Figure 1 is the XRD pattern of the photocatalyst; Figure 2 is the UV pattern of the photocatalyst; Figure 1 illustrates that the prepared material successfully supports N, S quantum dots, and Figure 2 illustrates that N, S quantum dots can increase visible light absorption.

Example 3

A preparation method of N,S quantum dots/bismuth tungstate composite photocatalyst, including the following steps:

(1) Dissolve 9.5mmol citric acid monohydrate and 8.8mmol cysteamine hydrochloride in 8ml distilled water, stir for 10min until completely dissolved, react at 80°C for 24h, then transfer the liquid to a polytetrafluoroethylene-lined stainless steel high-pressure In the kettle, react at 200°C for 3.5 hours; after cooling to room temperature, wash and freeze-dry to obtain brown powder, namely N and S quantum dots.

(2) Dissolve 20mmolBi(NO ₃ ) ₃ ·5H ₂ O in 20ml distilled water, add 5ml concentrated nitric acid solution, and obtain solution A; dissolve 10mmolNa ₂ WO ₄ ·2H ₂ O in 10ml distilled water, and obtain solution B under magnetic stirring. , add solution B dropwise to solution A, continue stirring for 24 hours, then wash and dry to obtain the Bi ₂ WO ₆ precursor;

(3) Mix the Bi ₂ WO ₆ precursor and the NaNO ₃ -KNO ₃ mixed salt at a mass ratio of 1:5 and grind them evenly; put the mixture into a muffle furnace and calcine at 350°C for 4 hours; finally, wash the product repeatedly with distilled water , dried at 80°C for 12 hours to obtain coral-like Bi ₂ WO ₆ .

(4) Dissolve 100 mg of Bi ₂ WO ₆ and 30 mg of N, S quantum dots in 20 ml of methanol; ultrasonic for 60 minutes, then stir and heat until the sample is completely dry to obtain the N, S quantum dots/bismuth tungstate composite photocatalyst, recorded For N, S/BW-0.3.

Example 4

A preparation method of N,S quantum dots/bismuth tungstate composite photocatalyst, including the following steps:

(1) Dissolve 9.5mmol citric acid monohydrate and 8.8mmol cysteamine hydrochloride in 8ml distilled water, stir for 10min until completely dissolved, react at 80°C for 24h, then transfer the liquid to a polytetrafluoroethylene-lined stainless steel high-pressure In the kettle, react at 200°C for 3.5 hours; after cooling to room temperature, wash and freeze-dry to obtain brown powder, namely N and S quantum dots.

(2) Dissolve 20mmolBi(NO ₃ ) ₃ ·5H ₂ O in 20ml distilled water, add 5ml concentrated nitric acid solution, and obtain solution A; dissolve 10mmolNa ₂ WO ₄ ·2H ₂ O in 10ml distilled water, and obtain solution B under magnetic stirring. , add solution B dropwise to solution A, continue stirring for 24 hours, then wash and dry to obtain the Bi ₂ WO ₆ precursor;

(3) Mix the Bi ₂ WO ₆ precursor and the NaNO ₃ -KNO ₃ mixed salt at a mass ratio of 1:5 and grind them evenly; put the mixture into a muffle furnace and calcine at 350°C for 4 hours; finally, wash the product repeatedly with distilled water , dried at 80°C for 12 hours to obtain coral-like Bi ₂ WO ₆ .

(4) Dissolve 100 mg of Bi ₂ WO ₆ and 40 mg of N, S quantum dots in 20 ml of methanol; ultrasonic for 60 minutes, then stir and heat until the sample is completely dry to obtain the N, S quantum dots/bismuth tungstate composite photocatalyst, recorded For N, S/BW-0.4.

Figure 3 is a comparison of the degradation performance test of the prepared N,S quantum dot/bismuth tungstate composite photocatalyst and the original bismuth tungstate sample. In the experiment of degrading the organic dye RhB (10mg/L), a 250W xenon lamp and a 420nm cut-off filter were used as visible light sources. The photocatalyst was dispersed in 50mL RhB solution and stirred in the dark for 30 minutes to achieve adsorption equilibrium. After 2 hours, 4 mL of reaction solution was extracted from the reactor every 20 minutes. After the reaction was completed, it was filtered with a 0.45 μm membrane filter to remove all photocatalytic materials. Each photocatalytic performance was measured with a UV-visible spectrophotometer (PG, UH-4150) at 554 nm. The results show that the photocatalytic degradation rate of the N,S quantum dot/bismuth tungstate composite photocatalyst is significantly higher than that of the original bismuth tungstate sample. The prepared N,S quantum dot/bismuth tungstate composite photocatalyst has good photocatalytic performance. Degradation performance.

Figure 4 is a degradation cycle stability chart of the N,S quantum dots/bismuth tungstate composite photocatalyst prepared in Example 2. It can be seen from the figure that the N,S quantum dots/bismuth tungstate composite photocatalyst has excellent cycle performance. It has good application prospects.

Claims (9)

1. The preparation method of the N, S quantum dot/bismuth tungstate composite photocatalyst is characterized by comprising the following steps of:

1) Mixing citric acid monohydrate, cysteamine hydrochloride and water, stirring until the mixture is completely dissolved, reacting, and freeze-drying to obtain N, S quantum dots;

2) Bi (NO) ₃ ) ₃ ·5H ₂ O and Na ₂ WO ₄ ·2H ₂ O is dissolved in water respectively to obtain a solution A and a solution B; dropwise adding the solution B into the solution A, stirring, filtering, washing and drying to obtain Bi ₂ WO ₆ A precursor;

3) Bi is mixed with ₂ WO ₆ Precursor and NaNO ₃ -KNO ₃ Mixing the mixed salts according to the mass ratio, calcining at high temperature, washing and drying to obtain coral Bi ₂ WO ₆ ；

4) Coral Bi ₂ WO ₆ And dissolving the N, S quantum dots in methanol, stirring and heating until the N, S quantum dots are completely dried to obtain the N, S quantum dots/bismuth tungstate composite photocatalyst; wherein coral Bi ₂ WO ₆ The dosage ratio of the N, S quantum dots to the methanol is 80-120 mg/10 mg-100 mg/20-30 ml.

2. The method for preparing the N, S quantum dot/bismuth tungstate composite photocatalyst as claimed in claim 1, wherein in the step 1), citric acid monohydrate, cysteamine hydrochloride and water are used in a ratio of 7-12 mmol:5-10 ml.

3. The method for preparing the N, S quantum dot/bismuth tungstate composite photocatalyst as claimed in claim 1, wherein in the step 1), the reaction is performed at 60-80 ℃ for 24-48 h, and then at 180-250 ℃ for 2-4 h.

4. The method for preparing the N, S quantum dot/bismuth tungstate composite photocatalyst as claimed in claim 1, wherein in the step 2), bi (NO ₃ ) ₃ ·5H ₂ The dosage ratio of O to water is 10-30 mmol to 20-40 ml; na (Na) ₂ WO ₄ ·2H ₂ The dosage ratio of O to water is 5-25 mmol to 10-30 ml; the solution A contains concentrated nitric acid solution, and the volume ratio of the concentrated nitric acid solution to water is 3-8 ml to 20-40 ml.

5. The method for preparing the N, S quantum dot/bismuth tungstate composite photocatalyst as claimed in claim 1, wherein in the step 2), stirring is carried out for 24-48 hours, and then filtering, washing and drying are carried out.

6. The method for preparing the N, S quantum dot/bismuth tungstate composite photocatalyst as claimed in claim 1, wherein in the step 3), bi ₂ WO ₆ Precursor and NaNO ₃ -KNO ₃ The mass ratio of (2) is 1:3-1:7.

7. The method for preparing the N, S quantum dot/bismuth tungstate composite photocatalyst as claimed in claim 1, wherein in the step 3), the calcination temperature is 300-450 ℃, the calcination time is 3-6 h, the drying temperature is 60-80 ℃, and the drying time is 12-24 h.

8. The N, S quantum dot/bismuth tungstate composite photocatalyst prepared by the method of any one of claims 1 to 7.

9. The use of the N, S quantum dot/bismuth tungstate composite photocatalyst as claimed in claim 8 in ambient photocatalysis.