WO2024088432A1

WO2024088432A1 - N-doped bismuth oxycarbonate composite graphite-phase carbon nitride material, and preparation method therefor and use thereof

Info

Publication number: WO2024088432A1
Application number: PCT/CN2023/129058
Authority: WO
Inventors: 华英杰; 贾仕豪; 王崇太; 韩慧敏
Original assignee: 海南师范大学
Priority date: 2023-10-25
Filing date: 2023-11-01
Publication date: 2024-05-02
Also published as: CN117380245A

Abstract

An N-doped bismuth oxycarbonate composite graphite-phase carbon nitride material, and a preparation method therefor and the use thereof, which belong to the technical field of photocatalytic materials for degrading wastewater pollutants. An N-doped bismuth oxycarbonate is synthesized by means of a hydrothermal method, and the N-doped bismuth oxycarbonate and graphite-phase carbon nitride are then condensed and refluxed by means of an electrostatic adsorption method to synthesize the N-doped bismuth oxycarbonate composite graphite-phase carbon nitride material. The N-doped bismuth oxycarbonate and the graphite-phase carbon nitride are effectively compounded, and the N-doped bismuth oxycarbonate and the graphite-phase carbon nitride are compounded to form an S-shaped heterojunction structure by means of the interaction between the N-doped bismuth oxycarbonate and the graphite-phase carbon nitride, such that the light absorption range can be widened, the light absorption intensity can be enhanced, the separation and transfer of photon-generated carriers can be promoted, and the photocatalytic degradation performance of organic dyes, antibiotics and phenolic pollutants in environmental water is further improved.

Description

A N-doped bismuth oxycarbonate composite graphite phase carbon nitride material and its preparation method and application

Technical Field

The invention belongs to the technical field of photocatalytic materials for degrading wastewater pollutants, and particularly relates to an N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material and a preparation method and application thereof.

Background technique

The increasing environmental pollution and the growing demand for clean energy are serious problems facing the world. Many strategies and solutions have been adopted to solve the above problems. Among them, photocatalytic technology has great potential in solving the current energy crisis and environmental degradation. Among various semiconductor photocatalytic materials, bismuth oxycarbonate is a promising photocatalyst because of its attractive morphology and excellent photochemical stability. However, the photocatalytic performance of bismuth oxycarbonate is limited by the following two reasons: (1) the wide band gap of bismuth oxycarbonate leads to poor visible light capture ability; (2) the electron-hole pairs generated by photocatalysis have a fast recombination rate in bismuth oxycarbonate, which limits its photocatalytic activity. Therefore, improving the photocatalytic efficiency of monomeric bismuth oxycarbonate remains a serious problem.

An effective way to improve the photocatalytic performance of single semiconductors is to utilize the synergistic effect between two promising semiconductors to construct a heterojunction. The close contact interface between the semiconductors, well-matched band energy and crystal plane coupling can effectively promote the separation and transfer of photogenerated electron-hole pairs, thereby accelerating surface photochemical reactions. Compared with traditional heterojunctions, new S-type heterojunction photocatalysts have attracted widespread attention due to their inherent advantages in band structure. The construction of S-type heterojunctions has become one of the effective methods to improve the photocatalytic performance of single semiconductors.

Based on this, the present invention proposes a method to improve the shortcomings of limited visible light response and fewer active sites of photocatalysts by constructing an S-type heterojunction in monomeric bismuth oxycarbonate.

Summary of the invention

In order to solve the above technical problems, the present invention proposes a N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material and its preparation method and application. The present invention synthesizes N-mixed bismuth oxycarbonate with uniform morphology by hydrothermal method, and synthesizes N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material by condensation reflux method using electrostatic adsorption method, effectively composites N-mixed bismuth oxycarbonate with graphite phase carbon nitride, and forms an effective and environmentally friendly S-type heterojunction of N-mixed bismuth oxycarbonate and monomer photocatalyst, overcoming the shortcomings of limited visible light response and fewer active sites of monomer photocatalyst, thereby generating more photogenerated carriers, and further improving the performance of photocatalytic degradation of organic dyes, antibiotics and phenolic pollutants in environmental water.

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

One of the technical solutions of the present invention:

A preparation method of an N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material comprises the following steps: synthesizing N-mixed bismuth oxycarbonate by a hydrothermal method, and condensing and refluxing the N-mixed bismuth oxycarbonate and graphite phase carbon nitride by an electrostatic adsorption method to synthesize the N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material.

Further, the hydrothermal synthesis of N-heterobismuth carbonate specifically includes the following steps:

Ammonium bismuth citrate and urea are placed in deionized water and stirred, and then polyvinyl pyrrolidone is added and stirred continuously, followed by hydrothermal treatment, centrifugation, washing and drying to obtain the N-heterobismuth carbonate.

Furthermore, the usage ratio of the ammonium bismuth citrate, urea and polyvinyl pyrrolidone is 2mmol:10mmol:600mg.

Furthermore, the temperature of the hydrothermal treatment is 60° C. and the time is 12 hours.

Furthermore, the process of synthesizing the N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material by condensing and refluxing the N-mixed bismuth oxycarbonate and graphite phase carbon nitride by electrostatic adsorption method specifically includes the following steps:

The graphite phase carbon nitride is dispersed with a methanol aqueous solution to obtain a suspension, the N-heterobismuth oxycarbonate is added to the suspension and stirred to obtain a mixture, the mixture is condensed and refluxed, and the N-heterobismuth oxycarbonate composite graphite phase carbon nitride material is obtained after washing and drying.

Furthermore, the concentration of the graphite phase carbon nitride in the suspension is 3-15wt%, and preferably 10wt%.

Furthermore, the usage ratio of the suspension to the N-heterobismuth oxycarbonate is 150 mL: 1 g.

Furthermore, the condensation reflux temperature is 75° C. and the time is 4 hours.

More specifically, the present invention provides a method for preparing a N-doped bismuth oxycarbonate composite graphite phase carbon nitride material, comprising the following steps:

Step S1: Preparation of N-heterobismuth oxycarbonate

2 mmol of ammonium bismuth citrate and 10 mmol of urea were placed in deionized water, and stirred at high speed for 40 min with a stirrer at a speed of 7000-8000 rpm, and then 600 mg of polyvinyl pyrrolidone was added to the above solution, and the high-speed stirring was continued for 50 min. After the stirring was completed, the solution was sealed in a 100 mL high-pressure reactor, and then hydrothermally treated at 60° C. for 12 h, and finally centrifuged, and washed with water and ethanol at 7000 rpm for 5 min, three times each, and dried for 12 h to obtain N-heterobismuth carbonate (p-BOC);

Step S2: Preparation of graphite phase carbon nitride

10 g of urea was placed in a 50 mL crucible and heated to 550° C. at a heating rate of 10° C. per minute in a muffle furnace. The temperature was maintained for 4 h. After the temperature of the muffle furnace was cooled, the urea was taken out and ground to obtain graphite phase carbon nitride (gC ₃ N ₄ );

Step S3: Preparation of N-doped bismuth oxycarbonate composite graphite phase carbon nitride material

Deionized water and methanol solution are mixed in a volume ratio of 1:1 to obtain a methanol aqueous solution, graphite phase carbon nitride is added to the methanol aqueous solution, and a completely dispersed suspension is obtained after ultrasonic treatment for 30 minutes, wherein the concentration of graphite phase carbon nitride in the suspension is 3-15wt%, 1gp-BOC is introduced into 150mL of the above suspension, and magnetic stirring is performed for 24 hours to obtain a mixture, and finally the mixture is evaporated, condensed and refluxed for 4 hours at 75°C as an ambient temperature under continuous stirring conditions, and the mixture is taken out and washed with water and ethanol at 7000rpm for 5 minutes, three times each, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain the N-heterocarbonate bismuth composite graphite phase carbon nitride material. Material (CN/p-BOC).

As a new type of organic photocatalyst, graphite carbon nitride has attracted much attention due to its inherent physical and chemical properties. The electronic structure and surface properties of graphite carbon nitride also make it a photocatalyst with potential applications for degrading pollutants and generating renewable energy. Its two-dimensional structure can provide a good contact plane with other semiconductors, and nanojunctions are more easily formed. In addition, the layered structure can promote the transfer of photogenerated charges on a tight interface, which is expected to improve the photocatalytic performance compared with a single photocatalyst.

The VB and CB of graphite carbon nitride are approximately 1.40 and -1.21 eV, respectively, and the VB and CB of N-heterobismuth carbonate are 1.48 and -0.78 eV, respectively. It can be seen that the band gaps of graphite carbon nitride and N-heterobismuth carbonate materials can be cross-matched to form a composite photocatalyst, which can achieve directional carrier migration and promote the separation of photogenerated electron-hole pairs, thereby enhancing photocatalytic activity. Combining these two semiconductors into a composite photocatalyst promotes directional carrier migration and achieves rapid separation of photogenerated electron-hole pairs, thereby enhancing photocatalytic activity.

The second technical solution of the present invention:

An N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material prepared by the above preparation method has a SEM image of a peony flower shape.

The third technical solution of the present invention:

Application of the above N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material in photocatalytic degradation of organic dyes, antibiotics or phenolic pollutants.

Compared with the prior art, the present invention has the following advantages and technical effects:

1. The present invention synthesizes uniform N-type bismuth carbonate by hydrothermal method, and synthesizes N-type bismuth carbonate and graphite carbon nitride into a composite material by condensation reflux using electrostatic adsorption method, thereby forming an effective and environmentally friendly S-type heterojunction of N-type bismuth carbonate composite graphite carbon nitride, which overcomes the disadvantages of monomer photocatalyst. It overcomes the shortcomings of limited visible light response and fewer active sites, accelerates charge separation, generates more photogenerated carriers, and improves the spectral response range of monomer photocatalysts, thereby achieving efficient visible light catalytic oxidation activity and further improving the photocatalytic degradation of organic dyes, antibiotics and phenolic pollutants in environmental water. It has the advantages of high photocatalytic efficiency, simple and fast method, and economy and environmental protection.

2. When preparing N-bismuth oxycarbonate composite graphite phase carbon nitride material, the present invention controls the ratio of graphite phase carbon nitride to N-bismuth oxycarbonate, thereby obtaining a composite material with a suitable energy band structure and optimal photocatalytic activity, thereby effectively improving the photocatalytic performance of the monomer.

3. The present invention utilizes the interaction between N-doped bismuth oxycarbonate and graphite-phase carbon nitride to compound N-doped bismuth oxycarbonate and graphite-phase carbon nitride to form an S-type heterojunction structure, which can broaden the light absorption range, enhance the light absorption intensity, and promote the separation and transfer of photogenerated carriers, thereby improving the photocatalytic degradation performance of the composite material.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

FIG1 is a schematic diagram of a synthesis process for preparing N-bismuth oxycarbonate composite graphite phase carbon nitride material (CN/p-BOC) in Example 1 of the present invention;

FIG2 is an SEM image of p-BOC, CN and 10 wt% CN/p-BOC prepared in Example 1 of the present invention, wherein a is p-BOC, b is CN, and c and d are 10 wt% CN/p-BOC at different magnifications;

FIG3 is a TEM image of p-BOC, CN and 10 wt% CN/p-BOC prepared in Example 1 of the present invention, wherein a is p-BOC, b is CN, and c and d are 10 wt% CN/p-BOC at different magnifications;

Figure 4 shows the photocatalytic degradation performance of the N-heterocarbonate bismuth composite graphite phase carbon nitride material prepared in different proportions under visible light for dye RhB (a), antibiotic TC (b) and CIP (c) and the degradation performance of all samples Kinetic curve of RhB (d).

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

All raw materials used in the embodiments of the present invention are purchased from commercial sources.

The technical solution of the present invention is further illustrated by the following embodiments.

Example 1

Step S1: Preparation of N-heterobismuth oxycarbonate

Step S2: Preparation of graphite phase carbon nitride

10 g of urea was placed in a 50 mL crucible and heated to 550° C. at a heating rate of 10° C. per minute in a muffle furnace. The temperature was maintained for 4 h. After the temperature of the muffle furnace was cooled, the urea was taken out and ground to obtain graphite phase carbon nitride (gC ₃ N ₄ , referred to as CN).

Deionized water and methanol solution are mixed in a volume ratio of 1:1 to obtain 150 mL of methanol aqueous solution, graphite phase carbon nitride is added to the methanol aqueous solution, and a completely dispersed suspension is obtained after ultrasonic treatment for 30 minutes, wherein the concentration of graphite phase carbon nitride in the suspension is 10 wt%, 1 g p-BOC is introduced into 150 mL of the above suspension, and a mixture is obtained by magnetic stirring for 24 hours. Finally, the mixture is evaporated, condensed and refluxed at 75°C as the ambient temperature under continuous stirring conditions for 4 hours, the mixture is taken out and washed with water and ethanol at 7000 rpm for 5 minutes, three times each, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain N-heterocarbonate bismuth composite graphite phase carbon nitride material (10wt% CN/p-BOC).

The schematic diagram of the synthesis process of preparing N-bismuth oxycarbonate composite graphite phase carbon nitride material (CN/p-BOC) in Example 1 of the present invention is shown in Figure 1.

Example 2

Same as Example 1, except that the concentration of graphite phase carbon nitride in the suspension is 3wt%, and the obtained 3wt%CN/p-BOC.

Example 3

Same as Example 1, except that the concentration of graphite phase carbon nitride in the suspension is 5 wt %, resulting in 5 wt % CN/p-BOC.

Example 4

Same as Example 1, except that the concentration of graphite phase carbon nitride in the suspension is 15 wt %, resulting in 15 wt % CN/p-BOC.

1. Morphology analysis

In order to verify the morphology and crystal phase characteristics of the N-mixed bismuth carbonate composite graphite phase carbon nitride material prepared by the present invention, the sample obtained in Example 1 was photographed with a thermal field emission scanning electron microscope (model: JSM-7001F) and a transmission electron microscope (model: JEOL JSM-2010). The results are shown in Figures 2 and 3. Figure 2 is a SEM image, a is the p-BOC prepared in Example 1, b is the CN prepared in Example 1, c and d are 10wt% CN/p-BOC prepared in Example 1 at different magnifications, and Figure 3 is a TEM image, a is the p-BOC prepared in Example 1, b is the CN prepared in Example 1, and c and d are 10wt% CN/p-BOC prepared in Example 1.

As can be seen from Figure 2, pure p-BOC is in the shape of a 3D peony flower ball with a diameter of about 1.3 μm, while CN shows a typical layered structure, indicating that it contains one or more layers of stacked graphite-like structures. The morphology of the 10wt% CN/p-BOC prepared in Example 1 is that the 3D p-BOC is wrapped by a CN layer with a two-dimensional structure, further indicating that CN is wrapped on p-BOC and the interface between CN and p-BOC is tight. The inset of Figure 3d shows that the lattice spacing of the 10wt% CN/p-BOC prepared in Example 1 is 0.273nm, corresponding to the (110) plane of p-BOC. The above results show that CN and p-BOC are closely connected, making it easier to form a heterostructure, which is beneficial to the transfer of photogenerated carriers and thus enhances the photocatalytic activity.

2. Performance Test

10 mg/L of dye RhB (rhodamine), antibiotic TC and antibiotic CIP were used as target pollutants for photocatalytic degradation to evaluate the visible light catalytic oxidation activity of the material prepared in the embodiment of the present invention.

1. Visible light catalytic oxidation activity of RhB

50 mg of samples (p-BOC prepared in Example 1, 10 wt% CN/p-BOC prepared in Example 1, 3 wt% CN/p-BOC prepared in Example 2, 5 wt% CN/p-BOC prepared in Example 3, and 15 wt% CN/p-BOC prepared in Example 4) were respectively placed in a photocatalytic reactor, and 100 mL of RhB (λ>400 nm) was photodegraded under a 250 W xenon lamp, and a blank control group (RhB) without adding a catalyst sample was set up.

A flowing cooling water system was used to maintain the temperature at 30 °C to avoid thermal catalysis. Before xenon lamp irradiation, the solution was magnetically stirred for 30 min to allow the photocatalyst to reach adsorption-desorption equilibrium on the material surface. After turning on the lamp, 3 mL of the solution was taken at intervals of 15 min, centrifuged and filtered through 0.2 μm polyethersulfone to remove particles for subsequent analysis. The concentration changes of the target pollutants were measured using a UV-visible spectrophotometer at the maximum absorption wavelengths of 554, 358 and 276 nm.

The results of the visible light photocatalytic oxidation activity measurement of RhB are shown in Figure 4a.

2. Visible light catalytic oxidation activity of TC

50 mg of samples (p-BOC and 10 wt% CN/p-BOC prepared in Example 1) were placed in a photocatalytic reactor, and 100 mL of TC (λ>400 nm) was photodegraded under a 250 W xenon lamp. A blank control group (TC) without adding a catalyst sample was set up.

Visible light photocatalytic oxidation activity of p-BOC and 10 wt% CN/p-BOC prepared in Example 1 for TC The measurement results are shown in Figure 4b.

3. Visible light catalytic oxidation activity of CIP

50 mg of samples (p-BOC and 10 wt% CN/p-BOC prepared in Example 1) were placed in a photocatalytic reactor, and 100 mL of CIP (λ>400 nm) was photodegraded under a 250 W xenon lamp. A blank control group (CIP) without adding a catalyst sample was set up.

The results of the visible light photocatalytic oxidation activity measurement of p-BOC and 10 wt % CN/p-BOC prepared in Example 1 for CIP are shown in FIG. 4 c .

4. Kinetic curve of RhB degradation

The kinetic curve results of RhB degradation by the samples (p-BOC prepared in Example 1, 10 wt% CN/p-BOC prepared in Example 1, 3 wt% CN/p-BOC prepared in Example 2, 5 wt% CN/p-BOC prepared in Example 3, and 15 wt% CN/p-BOC prepared in Example 4) and the blank group (Blank) are shown in Figure 4d.

According to FIG. 4 , it can be seen that the 10 wt % CN/p-BOC prepared in Example 1 has the best performance in degrading various pollutants.

The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

A method for preparing an N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material, characterized in that the N-mixed bismuth oxycarbonate is synthesized by a hydrothermal method, and the N-mixed bismuth oxycarbonate and graphite phase carbon nitride are condensed and refluxed by an electrostatic adsorption method to synthesize the N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material.
The method for preparing the N-bismuth oxycarbonate composite graphite phase carbon nitride material according to claim 1 is characterized in that the hydrothermal synthesis of N-bismuth oxycarbonate specifically comprises the following steps:

Ammonium bismuth citrate and urea are placed in deionized water and stirred, and then polyvinyl pyrrolidone is added and stirred continuously, followed by hydrothermal treatment, centrifugation, washing and drying to obtain the N-heterobismuth carbonate.
The method for preparing N-heterobismuth oxycarbonate composite graphite phase carbon nitride material according to claim 2 is characterized in that the amount ratio of the ammonium bismuth citrate, urea and polyvinyl pyrrolidone is 2mmol:10mmol:600mg.
The method for preparing N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material according to claim 2 is characterized in that the temperature of the hydrothermal treatment is 60° C. and the time is 12 hours.
The method for preparing the N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material according to claim 1 is characterized in that the process of synthesizing the N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material by condensing and refluxing the N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material by an electrostatic adsorption method specifically comprises the following steps:

The graphite phase carbon nitride is dispersed with a methanol aqueous solution to obtain a suspension, the N-heterobismuth oxycarbonate is added to the suspension and stirred to obtain a mixture, the mixture is condensed and refluxed, and the N-heterobismuth oxycarbonate composite graphite phase carbon nitride material is obtained after washing and drying.
The method for preparing the N-bismuth oxycarbonate composite graphite phase carbon nitride material according to claim 5, characterized in that the concentration of the graphite phase carbon nitride in the suspension is 3-15wt%.
The method for preparing the N-heterobismuth oxycarbonate composite graphite phase carbon nitride material according to claim 5 is characterized in that the usage ratio of the suspension to the N-heterobismuth oxycarbonate is 150 mL: 1 g.
The method for preparing the N-mixed bismuth oxycarbonate composite graphite phase carbon nitride material according to claim 5, Characterized in that the condensation reflux temperature is 75°C and the time is 4 hours.
A N-bismuth oxycarbonate composite graphite phase carbon nitride material prepared by the preparation method according to any one of claims 1 to 8.
Application of the N-heterobismuth oxycarbonate composite graphite phase carbon nitride material described in claim 9 in photocatalytic degradation of organic dyes, antibiotics or phenolic pollutants.