CN116351454A - Bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots, and preparation and application thereof - Google Patents

Abstract

The invention discloses a bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots, and preparation and application thereof, comprising bismuth oxychloride with a {010} crystal face mainly exposed and nitrogen-doped carbon quantum dots, wherein the nitrogen-doped carbon quantum dots are anchored on the {010} crystal face exposed by bismuth oxychloride. {010} bismuth oxychloride is an ultrathin irregular nano-sheet structure, and the mass percentage of the doped carbon quantum dots is 0.01% -0.08%. The photocatalyst is prepared by mixing bismuth nitrate pentahydrate with nitrogen-doped carbon quantum dot solution, adjusting pH by alkaline solution, and performing hydrothermal reaction, wherein the nitrogen-doped carbon quantum dot solution is prepared by performing hydrothermal reaction on ammonium citrate and ethylenediamine. The catalyst expands the photoresponse range by utilizing the synergistic effect of the high-energy exposed crystal face and the nitrogen doped carbon quantum dots, promotes the migration of photo-generated carriers and accelerates the generation of surface oxidation-reduction reaction, achieves the aim of improving the photocatalytic performance of bismuth oxychloride, has the degradation efficiency of 85.2% in wastewater polluted by antibiotics, and has the advantages of stable photocatalytic performance, strong corrosion resistance and the like.

Description

Bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots and its preparation and application

technical field

The invention belongs to the technical field of photocatalysis, and in particular relates to a bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots and its preparation and application.

Background technique

Antibiotics are one of the most popular multifunctional drugs because they can be used not only in disease treatment, infection prevention but also in promoting the growth of animals and plants, etc. The resulting abuse of antibiotics has led to a large amount of antibiotic residues entering aquatic ecosystems through soil erosion, animal manure and wastewater discharge, seriously threatening ecological security and human health. The application of semiconductor photocatalysis technology to degrade toxic and harmful persistent pollutants such as antibiotics in water is of great significance to solve the problem of water pollution. However, weak photoresponsiveness and low utilization of photogenerated carriers are still the bottlenecks in the design of semiconductor photocatalysts. Therefore, it is of great significance to actively develop efficient and renewable photocatalysts with visible light response to fully utilize solar energy.

Bismuth oxychloride has been considered as an effective photocatalyst for pollutant degradation due to its high chemical stability, unique layered structure, corrosion resistance, and good photocatalytic performance. However, the limited light absorption ability, high recombination rate of photogenerated electron-hole pairs, and slow surface reactions hinder their further applications.

Contents of the invention

In order to overcome the deficiencies in the prior art, the present invention provides a bismuth oxychloride-based photocatalyst with wide photoresponse range, high photogenerated electron-hole separation efficiency, high photocatalytic activity, good stability and corrosion resistance, and its preparation method and application.

In order to achieve the above object, the present invention first proposes a bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots, including bismuth oxychloride and nitrogen-doped carbon quantum dots, and the main exposed crystal plane of the bismuth oxychloride is {010 } crystal plane, the nitrogen-doped carbon quantum dots are anchored on the {010} crystal plane exposed by bismuth oxychloride, and the mass percentage of the nitrogen-doped carbon quantum dots is 0.01% to 0.08%,

Preferably, the mass percentage content of the nitrogen-doped carbon quantum dots is 0.02%.

Preferably, the diameter of the nitrogen-doped carbon quantum dot is <10nm.

Preferably, the bismuth oxychloride whose main exposed crystal plane is the {010} crystal plane has an ultra-thin irregular nanosheet structure.

Based on a general inventive concept, the present invention also provides a method for preparing a bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots, comprising the following steps:

S1. Add bismuth nitrate pentahydrate and nitrogen-doped carbon quantum dot solution to glycerol-water mixed solvent, and ultrasonically stir until a uniform mixed solution is formed;

S2. Add saturated sodium chloride solution dropwise to the mixed solution obtained in step S1, and stir evenly with ultrasonic;

S3, adding a certain concentration of alkaline solution dropwise to the mixed solution obtained in step S2 to adjust the pH to 5-7;

S4. Hydrothermally treating the mixed solution obtained in step S3 to obtain {010} bismuth oxychloride anchored by nitrogen-doped carbon quantum dots.

Preferably, the molar ratio of bismuth nitrate pentahydrate to nitrogen-doped carbon quantum dot solution in the S1 step is 1:0.002-0.008; the ultrasonic dispersion time is 15 min-40 min; the stirring time is 15 min-40 min.

Preferably, an excess saturated sodium chloride solution is added in the step S2; the ultrasonic dispersion time is 15 min to 40 min; the stirring time is 15 min to 40 min.

Preferably, the alkaline solution in step S3 is any one of sodium hydroxide solution or potassium hydroxide solution.

Preferably, in the step S4, the hydrothermal reaction temperature is 120-180° C., and the reaction time is 5-10 h.

Preferably, the preparation method of nitrogen-doped carbon quantum dots comprises the following steps: mixing ammonium citrate, ethylenediamine and water to obtain a precursor solution; performing a hydrothermal reaction on the precursor solution, and collecting the reacted solution The dialysis reaction is carried out to obtain a nitrogen-doped carbon quantum dot solution. Wherein, the molar ratio of ammonium citrate and ethylenediamine is 8-15:5-10, and the hydrothermal reaction temperature is 160-200°C; the hydrothermal reaction time is 3-8h; in the dialysis reaction, the solution and The volume ratio of ultrapure water is 1:80~120, and the dialysis time is 20~28h.

Based on a general inventive concept, the present invention also provides an application of a nitrogen-doped carbon quantum dot-anchored bismuth oxychloride photocatalyst in the catalytic degradation of antibiotics in wastewater, comprising the following steps:

S1: Mix the {010} bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots with wastewater containing antibiotic pollutants, and stir;

S2: Perform photocatalytic reaction under light conditions to complete the degradation of antibiotic pollutants;

Preferably, the photocatalyst is added in an amount of 0.2 g to 1.0 g per liter of wastewater containing organic pollutants.

Preferably, the antibiotic pollutant is ciprofloxacin.

Preferably, the initial concentration of the ciprofloxacin pollutant is 5mg/L-20mg/L; the light condition λ≥420nm; the photocatalytic reaction time ≥60min.

The main mechanism of action of the photocatalyst provided by the invention is:

The crystal facet effect is considered to promote the occurrence of surface redox reactions by regulating the coordination and arrangement of surface atoms. The up-conversion effect of nitrogen-doped carbon quantum dots can convert low-energy incident light into high-energy light emission, which helps to improve the utilization of solar energy. Therefore, utilizing the synergistic effect of facet regulation and anchoring of nitrogen-doped carbon quantum dots is of great significance for improving the photocatalytic performance of bismuth oxychloride.

Aiming at defects such as limited photoresponse ability of bismuth oxychloride, high recombination rate of photogenerated electron-hole pairs, and slow surface reaction, the present invention creatively adjusts the main exposed crystal plane of bismuth oxychloride to {010} high-energy crystal plane, and Nitrogen-doped carbon quantum dots are anchored on the crystal surface, and the synergistic effect of the high-energy exposed crystal surface and nitrogen-doped carbon quantum dots is used to expand the photoresponse range, promote the migration of photogenerated carriers, and accelerate the occurrence of surface redox reactions, thereby achieving The purpose of improving the photocatalytic performance of bismuth oxychloride. Specifically, the bismuth oxychloride exposed on the {010} crystal plane has a large surface area and open channel characteristics, which can provide more space for the loading of nitrogen-doped carbon quantum dots. Therefore, loading nitrogen-doped carbon quantum dots on the surface of bismuth oxychloride exposed to the {010} crystal plane can promote the formation of an effective heterojunction channel between nitrogen-doped carbon quantum dots and bismuth oxychloride, so as to better play Electron conductivity properties of nitrogen-doped carbon quantum dots. In addition, the terminal bismuth atoms with more exposed {010} crystal faces can be used as active sites for photocatalytic reactions, and the upconversion performance of nitrogen-doped carbon quantum dots can effectively improve the photoresponsiveness of photocatalysts. Therefore, the constructed nitrogen-doped carbon quantum dot-anchored {010} bismuth oxychloride photocatalyst exhibits excellent visible light absorption ability and photocatalytic performance. In addition, in the present invention, when the {010} bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots is applied to degrade antibiotic pollutants under simulated visible light (λ≥420nm) conditions, it shows a very excellent degradation effect, which can effectively Degradation of antibiotic pollutants in wastewater.

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

(1) The present invention provides a {010} bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots. First, the main exposed crystal planes of bismuth oxychloride nanosheets are adjusted to {010} crystal planes, and then Anchoring nitrogen-doped carbon quantum dots on {010} bismuth oxychloride nanosheets has the advantages of wide photoresponse range, high photogenerated electron-hole separation efficiency, high photocatalytic activity, good stability, and corrosion resistance. A new type of composite photocatalyst with excellent performance, by mixing {010} bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots with wastewater containing antibiotic pollutants, after stirring and photocatalytic reaction, antibiotic pollution in wastewater can be realized The effective degradation of pollutants has the advantages of stable photocatalytic performance, strong corrosion resistance, and high efficiency of pollutant degradation, and has a good practical application prospect.

(2) In the {010} bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots of the present invention, the main exposed crystal plane of bismuth oxychloride is optimized to be the {010} crystal plane, which is more conducive to nitrogen-doped carbon quantum dots The anchoring on the surface of bismuth oxychloride and the promotion of sufficient contact between the two can obtain more excellent photocatalytic performance, because the nitrogen-doped carbon quantum dots can be anchored on the {010} crystal plane of bismuth oxychloride. A covalent ring along the direction of [Bi2O2]2 ⁺ → N-CQDs → Cl- is formed at the heterojunction interface, which is beneficial to the directional transfer of electrons to form an interfacial electric field, which is beneficial to the transfer of photogenerated charges, making the prepared Photocatalysts have more excellent photocatalytic properties.

(3) In the {010} bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots of the present invention, the mass percentage of nitrogen-doped carbon quantum dots is optimized to be 0.01-0.08%. When the content of nitrogen-doped carbon quantum dots is too small, a small amount of nitrogen-doped carbon quantum dots is not enough to form an interfacial electric field that is conducive to charge transfer, and it is difficult to achieve effective separation and migration of photogenerated electron holes in bismuth-rich bismuth oxychloride nanosheets , and excessive nitrogen-doped carbon quantum dots will destroy the effective heterojunction cross-section, thereby reducing the photocatalytic activity. In particular, when the mass percentage of nitrogen-doped carbon quantum dots is 0.01% to 0.08%, the obtained {010} bismuth oxychloride photocatalyst anchored by cobalt nitrogen-doped carbon quantum dots has more excellent photocatalytic performance.

(4) The main exposed crystal plane of bismuth oxychloride controlled by alkaline solution is {010} high-energy crystal plane in the present invention; ammonium citrate, ethylenediamine and water are used as raw materials to obtain a crystal with a light-absorbing range by adopting a simple hydrothermal reaction. Nitrogen-doped carbon quantum dots with wide width and high light absorption efficiency; it has the advantages of simple synthesis method, low raw material cost, less energy consumption, short time consumption, easy control of conditions, and no by-products that pollute the environment during the preparation process. It is suitable for continuous large-scale mass production and is convenient for industrialized utilization.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

Fig. 1 is {010} bismuth oxychloride nanosheets (BOC-010), {001} bismuth oxychloride nanosheets (BOC-001) and {010} chlorine anchored by nitrogen-doped carbon quantum dots in Experimental Example 1 of the present invention. Scanning electron microscope images of bismuth oxide nanosheets (10NBOC-010), where Figure 1a is BOC-001, Figure 1b is BOC-010, and Figure 1c is 10NBOC-010;

Figure 2 shows {010} bismuth oxychloride nanosheets (BOC-010), {001} bismuth oxychloride nanosheets (BOC-001) and {010} chlorine anchored by nitrogen-doped carbon quantum dots in Experimental Example 2 of the present invention. TEM images of bismuth oxide nanosheets (10NBOC-010), where Figure 2a is BOC-001, Figure 2b is BOC-010, and Figure 2c is 10NBOC-010;

Figure 3 shows {010} bismuth oxychloride nanosheets (BOC-010), {001} bismuth oxychloride nanosheets (BOC-001), and {010} chlorine anchored by nitrogen-doped carbon quantum dots in Experimental Example 3 of the present invention. UV-Vis diffuse reflectance spectra of bismuth oxide nanosheets (10NBOC-010) and {001} bismuth oxychloride nanosheets anchored by nitrogen-doped carbon quantum dots (10NBOC-001);

Figure 4 shows {010} bismuth oxychloride nanosheets (BOC-010), {001} bismuth oxychloride nanosheets (BOC-001), and {010} chlorine anchored by nitrogen-doped carbon quantum dots in Experimental Example 4 of the present invention. Transient photocurrent maps of bismuth oxide nanosheets (10NBOC-010) and {001} bismuth oxychloride nanosheets (10NBOC-001) anchored by nitrogen-doped carbon quantum dots;

Figure 5 is a synergistic effect diagram of {010} bismuth oxychloride nanosheets (10NBOC-010) anchored by nitrogen-doped carbon quantum dots in Experimental Example 5 of the present invention, wherein Figure 5a is a three-dimensional differential charge density diagram of 10NBOC-010, Fig. 5b is the planar average differential charge density map of 10NBOC-010;

Fig. 6 is the result of the efficiency of BOC-010, BOC-001, 6NBOC-010, 10NBOC-010, 14NBOC-010 and 10NBOC-001 in Experimental Example 6 of the present invention to degrade antibiotic pollutants, wherein Fig. 6a is {010} bismuth oxychloride Nanosheets (BOC-010), {001} bismuth oxychloride nanosheets (BOC-001), {010} bismuth oxychloride nanosheets anchored by nitrogen-doped carbon quantum dots (6NBOC-010, 10NBOC-010, 14NBOC- 010) and nitrogen-doped carbon quantum dot anchored {001} bismuth oxychloride nanosheets (10NBOC-001) photocatalytic degradation of ciprofloxacin wastewater under visible light irradiation conditions corresponding to the time-degradation efficiency relationship diagram; Figure 6b shows the degradation coefficients of different materials BOC-010, BOC-001, 6NBOC-010, 10NBOC-010, 14NBOC-010 and 10NBOC-001.

Detailed ways

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will describe in detail with reference to the drawings and specific embodiments.

The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Without departing from the spirit and essence of the present invention, any modifications or substitutions made to the methods, steps or conditions of the present invention fall within the scope of the present invention.

If not specified, the technical means used in the examples are conventional means well known to those skilled in the art; if not specified, the reagents used in the examples are all commercially available.

Example 1

Preparation of nitrogen-doped carbon quantum dots

The specific preparation process of nitrogen-doped carbon quantum dots: add 10 mmol ammonium citrate to 20 mL ultrapure water, and stir until dissolved, then add 670 μL ethylenediamine dropwise. After stirring for 30 min, the mixed solution was sealed in a stainless steel reactor and placed in an oven at 200° C. for 5 h. After the reaction kettle was naturally cooled to room temperature, the resulting solution was dialyzed (MWCO 1000) for 24 hours at a volume ratio of solution: ultrapure water = 1:100, and finally an aqueous solution of N-CQDs with a concentration of about 0.5M was obtained.

Example 2

Preparation of bismuth oxychloride photocatalyst whose main exposed crystal plane is {010} plane

S1. Under stirring conditions, sequentially add 0.486 g of bismuth nitrate pentahydrate and 25 mL of ultrapure water into 25 mL of glycerol solution, and ultrasonically stir until a uniform mixed solution is formed;

S2. Add 5 mL of saturated NaCl solution dropwise to the mixed solution prepared in step S1, and ultrasonically stir until a uniform mixed solution is formed;

S3. Adjust the pH of the mixed solution obtained in step S2 to 6 with sodium hydroxide solution;

S4. Transfer the mixed solution with pH=6 obtained in step S3 to a 100mL stainless steel autoclave, conduct a hydrothermal reaction at 160°C for 6 hours, cool, centrifuge, wash with deionized water and ethanol, and dry to obtain the main exposed crystal planes It is a bismuth oxychloride photocatalyst on the {010} plane, named BOC-010.

Comparative example 1

Preparation of bismuth oxychloride photocatalyst whose main exposed crystal plane is {001} plane

S1. Under stirring conditions, sequentially add 0.486 g of bismuth nitrate pentahydrate and 25 mL of ultrapure water into 25 mL of glycerol solution, and ultrasonically stir until a uniform mixed solution is formed;

S2. Add 5 mL of saturated NaCl solution dropwise to the mixed solution prepared in step S1, and ultrasonically stir until a uniform mixed solution is formed;

S3. Transfer the mixed solution obtained in step S2 to a 100mL stainless steel autoclave, conduct a hydrothermal reaction at 160°C for 6 hours, cool, centrifuge, wash with deionized water and ethanol, and dry to obtain the main exposed crystal plane as {001 } surface bismuth oxychloride photocatalyst named BOC-001.

Example 3

Preparation of {010} bismuth oxychloride photocatalyst 6NBOC-010 anchored by nitrogen-doped carbon quantum dots

In this embodiment, the mass percentage of nitrogen-doped carbon quantum dots in the {010} bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots is 0.01%, and the mass percentage of {010} bismuth oxychloride nanosheets Mineral content is 99.99%.

Bismuth oxychloride nanosheets whose main exposed crystal face is the {010} plane are used as the carrier, and nitrogen-doped carbon quantum dots are anchored on the {010} bismuth oxychloride nanosheets. The preparation method is as follows:

S1. Under stirring conditions, add 0.486g of bismuth nitrate pentahydrate, 6mL of nitrogen-doped carbon quantum dot solution and 25mL of ultrapure water in sequence in 25mL of glycerol solution, and ultrasonically stir until a uniform mixed solution is formed;

S2. Add 5 mL of saturated NaCl solution dropwise to the mixed solution prepared in step S1, and ultrasonically stir until a uniform mixed solution is formed;

S3. Adjust the pH of the mixed solution obtained in step S2 to 6 with sodium hydroxide solution;

S4. Transfer the mixed solution with pH=6 obtained in step S3 to a 100mL stainless steel autoclave, conduct a hydrothermal reaction at 160°C for 6 hours, cool, centrifuge, wash with deionized water and ethanol, and dry to obtain the main exposed crystal planes It is a bismuth oxychloride photocatalyst on the {010} plane, named 6NBOC-010.

Example 4

Preparation of {010} bismuth oxychloride photocatalyst 10NBOC-010 anchored by nitrogen-doped carbon quantum dots

In this embodiment, the nitrogen-doped carbon quantum dot anchored {010} bismuth oxychloride photocatalyst has a mass percentage of nitrogen-doped carbon quantum dots of 0.02%, and a mass percentage of {010} bismuth oxychloride nanosheets The component content is 99.98%, and the preparation method is as follows:

S1. Under stirring conditions, add 0.486g of bismuth nitrate pentahydrate, 10mL of nitrogen-doped carbon quantum dot solution and 25mL of ultrapure water in sequence in 25mL of glycerol solution, and ultrasonically stir until a uniform mixed solution is formed;

S2. Add 5 mL of saturated NaCl solution dropwise to the mixed solution prepared in step S1, and ultrasonically stir until a uniform mixed solution is formed;

S3. Adjust the pH of the mixed solution obtained in step S2 to 6 with sodium hydroxide solution;

S4. Transfer the mixed solution with pH=6 obtained in step S3 to a 100mL stainless steel autoclave, conduct a hydrothermal reaction at 160°C for 6 hours, cool, centrifuge, wash with deionized water and ethanol, and dry to obtain the main exposed crystal planes It is a bismuth oxychloride photocatalyst on the {010} plane, named 10NBOC-010.

Example 5

Preparation of {010} bismuth oxychloride photocatalyst 14NBOC-010 anchored by nitrogen-doped carbon quantum dots

In this embodiment, the mass percentage of nitrogen-doped carbon quantum dots in the {010} bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots is 0.03%, and the mass percentage of {010} bismuth oxychloride nanosheets The component content is 99.97%, and the preparation method is as follows:

S1. Under stirring conditions, add 0.486g of bismuth nitrate pentahydrate, 14mL of nitrogen-doped carbon quantum dot solution and 25mL of ultrapure water in sequence in 25mL of glycerol solution, and ultrasonically stir until a uniform mixed solution is formed;

S2. Add 5 mL of saturated NaCl solution dropwise to the mixed solution prepared in step S1, and ultrasonically stir until a uniform mixed solution is formed;

S3. Adjust the pH of the mixed solution obtained in step S2 to 6 with sodium hydroxide solution;

S4. Transfer the mixed solution with pH=6 obtained in step (3) to a 100mL stainless steel autoclave, conduct a hydrothermal reaction at 160°C for 6 hours, cool, centrifuge, wash with deionized water and ethanol, and dry to obtain the main exposure Bismuth oxychloride photocatalyst whose crystal plane is {010} plane is named 14NBOC-010.

Comparative example 2

Preparation of {001} bismuth oxychloride photocatalyst 10NBOC-001 anchored by nitrogen-doped carbon quantum dots

In this comparative example, the mass percent content of nitrogen-doped carbon quantum dots in the {001} bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots is 0.02%, and the mass percent of {010} bismuth oxychloride nanosheets Mineral content is 99.98%.

Using bismuth oxychloride nanosheets whose main exposed crystal plane is the {001} plane as a carrier, {001} bismuth oxychloride nanosheets are anchored with nitrogen-doped carbon quantum dots. The preparation method is as follows:

S1. Under stirring conditions, add 0.486g of bismuth nitrate pentahydrate, 10mL of nitrogen-doped carbon quantum dot solution and 25mL of ultrapure water in sequence in 25mL of glycerol solution, and ultrasonically stir until a uniform mixed solution is formed;

S1. Add 5 mL of saturated NaCl solution dropwise to the mixed solution prepared in step S1, and ultrasonically stir until a uniform mixed solution is formed;

S1. Transfer the mixed solution obtained in step S2 to a 100mL stainless steel autoclave, conduct a hydrothermal reaction at 160°C for 6 hours, cool, centrifuge, wash with deionized water and ethanol, and dry to obtain the main exposed crystal plane as {010 } surface bismuth oxychloride photocatalyst, named 10NBOC-001.

Experimental example 1

Investigate the structural characteristics of BOC-001, BOC-010, 10NBOC-010

For {001} bismuth oxychloride photocatalyst (BOC-001), {010} bismuth oxychloride photocatalyst (BOC-010), nitrogen-doped carbon quantum dots anchored on {010} bismuth oxychloride nanosheets (10NBOC-010 ) scanning electron microscope to investigate the structural characteristics of these three materials, the results are shown in Figure 1, Figure 1(a) shows that the structural characteristics of {001} bismuth oxychloride photocatalyst is a two-dimensional sheet-like tetragonal structure, Figure 1(b ) shows that the structure of {010} bismuth oxychloride photocatalyst is an ultrathin irregular nanosheet structure. It can be seen from Fig. 1(c) that nitrogen-doped carbon quantum dots are anchored on the surface of {010} bismuth oxychloride nanosheets , compared with the {010} bismuth oxychloride nanosheet structure shown in Fig. 1(b), the loading of nitrogen-doped carbon quantum dots does not change the structure of {010} bismuth oxychloride nanosheets.

Experimental example 2

Investigating the exposure characteristics of crystal planes of BOC-010, BOC-001, and 10NBOC-010

Inspection of {010} bismuth oxychloride nanosheets (BOC-010), {001} bismuth oxychloride nanosheets (BOC-001) and {010} bismuth oxychloride nanosheets anchored by nitrogen-doped carbon quantum dots by transmission electron microscopy (10NBOC-010) facet exposed features.

The results are shown in Figure 2, where a is BOC-001, b is BOC-010, and c is 10NBOC-010. It can be seen from Figure 2a that the clear lattice fringes of BOC-001 with a interplanar spacing of 0.275 nm correspond to the {110} atomic plane perpendicular to the {001} atomic plane, that is, the main exposed crystal plane of BOC-001 is the {001} crystal plane ; It can be seen from Figure 2b that the (002) atomic plane with a lattice spacing of 0.37nm can be clearly observed, that is, BOC-010 is mainly surrounded by {010} planes. It can be seen from Fig. 2c that nitrogen-doped carbon quantum dots with a diameter of about 8 nm are distributed on the surface of {010} bismuth oxychloride.

Experimental example 3

Investigate the photoresponse performance of BOC-010, BOC-001, 10NBOC-010, 10NBOC-001

{010} bismuth oxychloride nanosheets (BOC-010), {001} bismuth oxychloride nanosheets (BOC-001), and {010} bismuth oxychloride anchored by nitrogen-doped carbon quantum dots by UV-vis diffuse reflectance spectroscopy Nanosheets (10NBOC-010) and {001} bismuth oxychloride nanosheets (10NBOC-001) anchored by nitrogen-doped carbon quantum dots were tested for photoresponse performance.

The result is shown in Figure 3. The light absorption edges of BOC-010 and BOC-001 are 351nm and 375nm, respectively. After anchoring nitrogen-doped carbon quantum dots, the absorption edge of 10NBOC-001 has a slight red shift (360nm), and 10NBOC-010 also has a slight red shift (390nm). Nitrogen-doped carbon quantum dots can broaden the absorption edge of bismuth oxychloride Photoresponsive range but limited action. However, focusing on the photoresponse of the catalyst to wavelengths from 280nm to 800nm, it can be seen that after loading nitrogen-doped carbon quantum dots, the light absorption intensity of 10NBOC-010 in this range is significantly stronger than that of 10NBOC-001. This is mainly because nitrogen-doped carbon quantum dots can act as photosensitizers and act as light-absorbing centers of photocatalysts, and the interfacial charge transfer effect between nitrogen-doped carbon quantum dots and bismuth oxychloride {010} crystal planes can also promote light absorption. Performance improvements.

Experimental example 4

Investigation of the photogenerated carrier migration performance of BOC-010, BOC-001, 10NBOC-010, 10NBOC-001

The prepared {010} bismuth oxychloride nanosheets (BOC-010), {001} bismuth oxychloride nanosheets (BOC-001), and {010} oxychloride anchored by nitrogen-doped carbon quantum dots were investigated by electrochemical experiments. Bismuth nanosheets (10NBOC-010) and {001} bismuth oxychloride nanosheets (10NBOC-001) anchored by nitrogen-doped carbon quantum dots were used to detect the mobility of photogenerated carriers.

The result is shown in Figure 4. The carrier separation efficiency of BOC-010 is lower than that of BOC-001, but the carrier separation efficiency of 10NBOC-010 is better than that of 10NBOC-001 when the same amount of nitrogen-doped carbon quantum is loaded. This phenomenon indicates that nitrogen-doped carbon quantum dots and {010} crystal planes of bismuth oxychloride have a synergistic effect in promoting carrier separation.

Experimental example 5

Investigation of the synergistic effect of nitrogen-doped carbon quantum dots and {010} facets of bismuth oxychloride anchored by nitrogen-doped carbon quantum dots in {010} bismuth oxychloride nanosheets (10NBOC-010)

Analysis of nitrogen-doped carbon quantum dots and {010} crystal planes of bismuth oxychloride nanosheets (10NBOC-010) anchored by nitrogen-doped carbon quantum dots by calculating the three-dimensional and in-plane average differential charge densities synergy.

The results are shown in Figure 5. In Figure 5a, a covalent ring along the direction of [Bi ₂ O ₂ ] ²⁺ →N-CQDs→Cl ^- can be observed, which is conducive to the directional transfer of electrons and the formation of an interfacial electric field; it can be seen from Figure 5b , the electrons of the nitrogen-doped carbon quantum dots in the 10NBOC-010 composite interface are transferred to the bismuth oxychloride {010} crystal plane, thereby forming an interface electric field pointing from the nitrogen-doped carbon quantum dots to the bismuth oxychloride {010} crystal plane , which is conducive to the transfer of photogenerated charges at the heterointerface of 10NBOC-010 under light conditions.

Experimental example 6

Investigate the efficiency of BOC-010, BOC-001, 6NBOC-010, 10NBOC-010, 14NBOC-010 and 10NBOC-001 in degrading antibiotic pollutants

Utilize materials BOC-010, BOC-001, 6NBOC-010, 10NBOC-010, 14NBOC-010 and 10NBOC-001 to degrade ciprofloxacin (CIP) in water, including the following steps:

S1. Weigh {010} bismuth oxychloride photocatalyst (BOC-010), {001} bismuth oxychloride photocatalyst (BOC-001), {010} bismuth oxychloride anchored by nitrogen-doped carbon quantum dots (6NBOC- 010, 10NBOC-010, 14NBOC-010) and {001} bismuth oxychloride (10NBOC-001) anchored by nitrogen-doped carbon quantum dots (0.02g), were added to 50mL of ciprofloxacin at a concentration of 10mg/L (CIP) wastewater, magnetically stirred for one hour in the dark to reach adsorption equilibrium

S2. Turn on the light source (xenon lamp), irradiate with visible light (λ≥420nm) to carry out the photocatalytic reaction for 60 minutes, and complete the degradation of CIP in the wastewater.

S3. Take 3 mL of the photocatalytic degradation solution in the reaction vessel every 10 minutes, filter it with a 0.45 μm filter head, and detect the degradation efficiency of the filtrate with an ultraviolet-visible spectrophotometer.

The results are shown in Figure 6, and Figure 6a shows the corresponding time-degradation efficiency of BOC-010, BOC-001, 6NBOC-010, 10NBOC-010, 14NBOC-010 and 10NBOC-001 in photocatalytic degradation of CIP wastewater under visible light irradiation conditions relationship diagram. In the figure, Ct represents the concentration of degraded CIP, and C represents the initial concentration of CIP.

It can be seen from Fig. 6 that the degradation efficiency of {010} bismuth oxychloride photocatalyst (BOC-010) to CIP is 33.9% after photocatalytic reaction for 60 min.

The nitrogen-doped carbon quantum dot-anchored {010} bismuth oxychloride photocatalyst (6NBOC-010) had a photocatalytic degradation efficiency of 76.9% for CIP after 60 min of photocatalytic reaction.

The nitrogen-doped carbon quantum dot-anchored {010} bismuth oxychloride photocatalyst (10NBOC-010) had a photocatalytic degradation efficiency of 85.2% for CIP after 60 min of photocatalytic reaction.

The nitrogen-doped carbon quantum dot-anchored {010} bismuth oxychloride photocatalyst (14NBOC-010) had a photocatalytic degradation efficiency of 80.4% for CIP after 60 min of photocatalytic reaction.

The degradation efficiency of {001} bismuth oxychloride photocatalyst (BOC-001) to CIP was 9.4% in photocatalytic reaction for 60min.

The degradation efficiency of {001} bismuth oxychloride photocatalyst (10NBOC-001) to CIP was 63.4% in photocatalytic reaction for 60min.

It can be seen that the order of degradation efficiency from high to low is: nitrogen-doped carbon quantum dot anchored {010} bismuth oxychloride photocatalyst (10NBOC-010) > nitrogen-doped carbon quantum dot anchored {010} oxychloride photocatalyst Bismuth photocatalyst (14NBOC-010) > {010} bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots (6NBOC-010) > {001} bismuth oxychloride photocatalyst (10NBOC-001) > {010} chlorine Bismuth Oxide Photocatalyst (BOC-010)>{001} Bismuth Oxychloride Photocatalyst (BOC-001).

Figure 6b shows the degradation coefficients of BOC-010, BOC-001, 6NBOC-010, 10NBOC-010, 14NBOC-010 and 10NBOC-001 treatments.

When the mass percentage of nitrogen-doped carbon quantum dots in {010} bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots is 0.02%, and the mass percentage of {010} bismuth oxychloride nanosheets is 99.98% In addition, the mass percentage of nitrogen-doped carbon quantum dots is too high or too low will significantly affect the degradation efficiency of the material.

The above description is a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. A bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots, characterized in that it comprises bismuth oxychloride and nitrogen-doped carbon quantum dots, and the main exposed crystal face of the bismuth oxychloride is {010}, so The nitrogen-doped carbon quantum dots are anchored on the exposed {010} crystal plane of bismuth oxychloride, and the mass percentage of the nitrogen-doped carbon quantum dots is 0.01-0.08%. 2. The nitrogen-doped carbon quantum dot anchored bismuth oxychloride photocatalyst according to claim 1, characterized in that the diameter of the nitrogen-doped carbon quantum dot is <10nm. 3. The nitrogen-doped carbon quantum dot anchored bismuth oxychloride photocatalyst according to claim 1, characterized in that the bismuth oxychloride is an ultra-thin irregular nanosheet structure. 4. A preparation method of a nitrogen-doped carbon quantum dot-anchored bismuth oxychloride photocatalyst, characterized in that, comprising the following steps: S1. Add bismuth nitrate pentahydrate and nitrogen-doped carbon quantum dot solution to a mixed solvent of glycerol and water, and ultrasonically stir until a uniform mixed solution is formed; S2. Add saturated sodium chloride solution dropwise to the mixed solution obtained in step S1, and stir evenly with ultrasonic; S3, adding an alkaline solution dropwise to the mixed solution obtained in step S2 to adjust the pH to 5-7; S4. The mixed solution obtained in step S3 is subjected to hydrothermal reaction, cooled, centrifuged, washed with deionized water and ethanol, and dried to obtain {010} bismuth oxychloride anchored by nitrogen-doped carbon quantum dots. 5. The preparation method according to claim 4, characterized in that, the molar ratio of bismuth nitrate pentahydrate and nitrogen-doped carbon quantum dot solution in the S1 step is 1:0.002～0.008; The volume ratio of alcohol to water is 1:0.5~1. 6. The preparation method according to claim 4, characterized in that, in the step S3, the alkaline solution is any one of sodium hydroxide solution or potassium hydroxide solution. 7. The preparation method according to claim 4, characterized in that, in the step S4, the hydrothermal reaction temperature is 120-180° C., and the reaction time is 5-10 h. 8. A bismuth oxychloride photocatalyst anchored by nitrogen-doped carbon quantum dots as claimed in any one of claims 1 to 3 or a nitrogen-doped photocatalyst prepared by the preparation method according to any one of claims 4 to 7. Application of bismuth oxychloride photocatalyst anchored by carbon quantum dots in the catalytic degradation of antibiotics in wastewater. 9. application according to claim 8, is characterized in that, described photocatalyst degrades the antibiotic in waste water and comprises the following steps: the bismuth oxychloride photocatalyst anchored by described nitrogen-doped carbon quantum dot and containing antibiotic pollutant Wastewater is mixed, stirred, and photocatalytic reaction is carried out under light conditions to complete the degradation of antibiotic pollutants; The photocatalyst is added in an amount of 0.2g-1.0g per liter of antibiotic-containing wastewater. 10. application according to claim 9, is characterized in that, described antibiotic pollutant is ciprofloxacin, and the initial concentration of described ciprofloxacin pollutant is 5mg/L～20mg/L; λ≥420nm; the photocatalytic reaction time≥60min.

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