阅读说明：本技术 一种石墨烯基锌掺杂钼酸铋催化剂的制备方法及其光催化应用 (Preparation method and photocatalytic application of graphene-based zinc-doped bismuth molybdate catalyst ) 是由 何光裕 陈海群 王强 赵宜涛 陈群 朱俊武 付永胜 于 2021-10-15 设计创作，主要内容包括：本发明属于光催化降解领域,涉及一种石墨烯基锌掺杂钼酸铋催化剂的制备方法及其光催化应用。具体步骤为：将氧化石墨置于溶剂中超声分散均匀,将预处理的硝酸铋和钼酸钠混合溶液滴加至上述分散液中,并搅拌均匀,再向其中加入一定量的乙酸锌,通过搅拌使体系充分混合均匀,调节pH,最后进行溶剂热反应,在抽滤、洗涤和干燥后研磨得到石墨烯基铋系纳米复合材料。本发明的制备方法简单,原材料廉价易得,绿色环保,其对水中环丙沙星的的降解中表现出极高的光催化降解效率。(The invention belongs to the field of photocatalytic degradation, and relates to a preparation method and photocatalytic application of a graphene-based zinc-doped bismuth molybdate catalyst. The method comprises the following specific steps: placing graphite oxide in a solvent for uniform ultrasonic dispersion, dropwise adding a pretreated bismuth nitrate and sodium molybdate mixed solution into the dispersion, uniformly stirring, adding a certain amount of zinc acetate, fully and uniformly mixing the system by stirring, adjusting the pH value, finally carrying out solvothermal reaction, and grinding after suction filtration, washing and drying to obtain the graphene-based bismuth nano composite material. The preparation method is simple, the raw materials are cheap and easy to obtain, the environment is protected, and the degradation of the ciprofloxacin in water shows high photocatalytic degradation efficiency.)

1. A preparation method of a graphene-based zinc-doped bismuth molybdate catalyst is characterized by comprising the following steps: comprises the steps of (a) preparing a mixture of a plurality of raw materials,

placing graphite oxide in a solvent 1, and uniformly dispersing by ultrasonic to obtain a graphene oxide solution; adding bismuth nitrate and sodium molybdate into the solvent 2, and uniformly stirring to obtain a solution 3;

dripping the solution 3 into the graphene oxide solution, and uniformly stirring; adding zinc solution, stirring again to fully and uniformly mix the system, and adjusting the pH value to obtain mixed solution;

and uniformly stirring the mixed solution, carrying out a solvothermal reaction, carrying out suction filtration, washing and drying, and grinding to obtain the graphene-based zinc-doped bismuth molybdate nano composite material.

2. The method of claim 1, wherein the graphene-based zinc-doped bismuth molybdate catalyst comprises: the mass ratio of graphene oxide to solvent in the graphene oxide solution is 1: 1090-4360.

3. The method of claim 1, wherein the graphene-based zinc-doped bismuth molybdate catalyst comprises: the mass ratio of the bismuth nitrate to the sodium molybdate is 6-2: 1; the mass ratio of the total solute of the bismuth nitrate and the sodium molybdate to the solvent 2 is 1: 10 to 20.

4. The method of claim 1, wherein the graphene-based zinc-doped bismuth molybdate catalyst comprises: the solvent 1 and the solvent 2 are one or more of water, ethanol, glycol and the like.

5. The method of claim 1, wherein the graphene-based zinc-doped bismuth molybdate catalyst comprises: the zinc solution is a solution containing zinc ions, including but not limited to zinc acetate.

6. The method of claim 1, wherein the graphene-based zinc-doped bismuth molybdate catalyst comprises: the molar ratio of zinc ions to bismuth nitrate in the zinc solution in the mixed solution is 0-1: 9, and the mass ratio of graphene oxide to the total graphene-based zinc-doped bismuth molybdate catalyst is 0-1: 13.

7. The method of claim 1, wherein the graphene-based zinc-doped bismuth molybdate catalyst comprises: and adjusting the pH value of the mixed solution to 5-9.

8. The method of claim 1, wherein the graphene-based zinc-doped bismuth molybdate catalyst comprises: the reaction temperature of the solvothermal reaction is 120-200 ℃, and the solvothermal reaction time is 12-24 h.

9. The method of claim 8, wherein the graphene-based zinc-doped bismuth molybdate catalyst comprises: the solvothermal reaction temperature is 160 ℃, and the solvothermal reaction time is 20 h.

10. The photocatalytic application of the product prepared by the preparation method of the graphene-based zinc-doped bismuth molybdate catalyst according to claims 1 to 9 is characterized in that: the application comprises that the ciprofloxacin is used for photocatalytic degradation.

Technical Field

The invention belongs to the technical field of photocatalytic degradation, and particularly relates to a preparation method and photocatalytic application of a graphene-based zinc-doped bismuth molybdate catalyst.

Background

Today, rapid development of industrialization and urbanization leads to global energy shortage, and a large amount of toxic and harmful chemical pollutants are discharged to the environment around us. Therefore, there is a need to find new green technologies to solve the above mentioned energy and environmental crisis. Semiconductor photocatalytic technology is considered as one of safe and effective methods for solving global energy shortage and environmental pollution. The semiconductor photocatalytic material can effectively utilize solar energy to thoroughly decompose organic matters into CO₂Inorganic micromolecules such as water and the like, and no secondary pollution is caused; meanwhile, water can be directly decomposed by utilizing the photocatalysis technology to prepare clean energy hydrogen, so that the two problems of energy shortage and environmental pollution are fundamentally solved.

The semiconductor photocatalysis technology has high performance and mineralization efficiency in the aspect of antibiotic treatment. Among various photocatalytic materials, bismuth-based semiconductors exhibit a good effect of photodegradation of antibiotics due to their excellent visible light absorption and high chemical stability. Wherein, Bi₂MoO₆Has lower band gap and unique layered structure, and is one kind of promising photocatalytic material. However, since Bi₂MoO₆Has the defects of fast carrier recombination, slow carrier migration, weak visible light response, easy agglomeration and the like, and Bi₂MoO₆The use as a photocatalyst is limited.

Scientific researchers have demonstrated that the agglomeration of nanomaterials can be inhibited by loading the nanomaterials on a carrier. Graphene, as a two-dimensional carbon-based nanomaterial, has a very large specific surface area, good adsorbability and a very high electron mobility, and has become the first choice for carriers. A small amount of metal ions are doped in the semiconductor catalyst, so that a shallow potential capture well of a photo-generated electron-hole pair can be formed, photo-generated electrons on a conduction band and photo-generated holes on a valence band can be captured, the photo-generated electrons and the holes can be effectively separated, the recombination probability of the electrons and the holes is reduced, and the aim of improving the photocatalytic activity of the semiconductor is fulfilled.

Disclosure of Invention

This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.

The present invention has been made keeping in mind the above problems occurring in the prior art.

Therefore, the invention aims to provide a simple solvent method for preparing the efficient graphene-based bismuth-system nano composite material, and the Zn with the best photocatalytic performance is prepared by taking reduced graphene oxide as a carrier and doping zinc ions_0.1Bi_1.9MoO₆/RGO₅A nanocomposite; the invention also provides application of the material in photocatalytic degradation of ciprofloxacin as a pollutant in water.

To solve the above technical problem, according to an aspect of the present invention, the present invention provides the following technical solutions: a preparation method of a graphene-based zinc-doped bismuth molybdate catalyst comprises the following steps,

placing graphite oxide in a solvent 1, and uniformly dispersing by ultrasonic to obtain a graphene oxide solution; adding bismuth nitrate and sodium molybdate into the solvent 2, and uniformly stirring to obtain a solution 3;

dripping the solution 3 into the graphene oxide solution, and uniformly stirring; adding zinc solution, stirring again to fully and uniformly mix the system, and adjusting the pH value to obtain mixed solution;

and uniformly stirring the mixed solution, carrying out a solvothermal reaction, carrying out suction filtration, washing and drying, and grinding to obtain the graphene-based zinc-doped bismuth molybdate nano composite material.

As a preferable embodiment of the preparation method of the graphene-based zinc-doped bismuth molybdate catalyst, the preparation method comprises the following steps: the mass ratio of graphene oxide to solvent in the graphene oxide solution is 1: 1090-4360.

As a preferable embodiment of the preparation method of the graphene-based zinc-doped bismuth molybdate catalyst, the preparation method comprises the following steps: the mass ratio of the bismuth nitrate to the sodium molybdate is 6-2: 1; the mass ratio of the total solute of the bismuth nitrate and the sodium molybdate to the solvent 2 is 1: 10 to 20.

As a preferable embodiment of the preparation method of the graphene-based zinc-doped bismuth molybdate catalyst, the preparation method comprises the following steps: the solvent 1 and the solvent 2 are one or more of water, ethanol, glycol and the like.

As a preferable embodiment of the preparation method of the graphene-based zinc-doped bismuth molybdate catalyst, the preparation method comprises the following steps: the zinc solution is a solution containing zinc ions, including but not limited to zinc acetate.

As a preferable embodiment of the preparation method of the graphene-based zinc-doped bismuth molybdate catalyst, the preparation method comprises the following steps: the molar ratio of zinc ions to bismuth nitrate in the zinc solution in the mixed solution is 0-1: 9, and the mass ratio of graphene oxide to the total graphene-based zinc-doped bismuth molybdate catalyst is 0-1: 13.

As a preferable embodiment of the preparation method of the graphene-based zinc-doped bismuth molybdate catalyst, the preparation method comprises the following steps: and adjusting the pH value of the mixed solution to 5-9.

As a preferable embodiment of the preparation method of the graphene-based zinc-doped bismuth molybdate catalyst, the preparation method comprises the following steps: the reaction temperature of the solvothermal reaction is 120-200 ℃, and the solvothermal reaction time is 12-24 h.

As a preferable embodiment of the preparation method of the graphene-based zinc-doped bismuth molybdate catalyst, the preparation method comprises the following steps: the solvothermal reaction temperature is 160 ℃, and the solvothermal reaction time is 20 h.

As a preferred scheme of the photocatalytic application of the product prepared by the preparation method of the graphene-based zinc-doped bismuth molybdate catalyst, the preparation method comprises the following steps: the application comprises that the ciprofloxacin is used for photocatalytic degradation.

The invention has the beneficial effects that:

zn prepared by the invention_0.1Bi_1.9MoO₆The size of the zinc ion doped composite material is 70-80nm, and when graphene is introduced, Zn is added_0.1Bi_1.9MoO₆/RGO₅The composite size is reduced and the components are uniformly distributed. In the course of photocatalytic degradation, Zn_0.1Bi_1.9MoO₆/RGO₅The complex being favored by electrons from Zn_0.1Bi_1.9MoO₆Transfer to graphene sheets, increase the specific surface area of the composite, expose more active sites and increase the photocatalytic performance of the composite material. In addition, the composite material is doped with zinc, graphene and Bi₂MoO₆Has good synergistic effect, thereby increasing the photocatalytic performance of the composite material.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:

FIG. 1 is Zn_0.1Bi_1.9MoO₆/RGO₅、Zn_0.1Bi_1.9MoO₆、Bi₂MoO₆XRD patterns of RGO and GO; wherein, the horizontal coordinate refers to the scanning angle of XRD, and each peak refers to different crystal planes;

FIG. 2 is a TEM image of different materials, wherein (a) is Bi₂MoO₆And (b) is Zn_0.1Bi_1.9MoO₆/RGO₅(ii) a It can be seen from FIG. (a) that Bi₂MoO₆The size of the nano-sheets is approximately 180-200nm, and the nano-sheets are stacked with each other, and the agglomeration phenomenon occurs. However, as can be seen from the graph (b), Zn_0.1Bi_1.9MoO₆/RGO₅In the composite Bi₂MoO₆Is significantly reduced, approximately 70-80nm, and grows relatively uniformly on the RGO lamellae, indicating that the addition of RGO solves Bi well₂MoO₆The nano-sheets are easy to agglomerate. This is probably because RGO has a large specific surface area and is advantageous for Bi₂MoO₆Growth of the nanoplatelets, which will increase Zn_0.1Bi_1.9MoO₆/RGO₅The contact of the compound and reactants in the reaction is beneficial to the photocatalytic degradation of CIP.

FIG. 3 shows Bi obtained₂MoO₆、Bi₂MoO₆/RGO、Zn_0.1Bi₂MoO₆And Zn_0.1Bi_1.9MoO₆/RGO₅The composite material is used for photocatalytic degradation of ciprofloxacin under the irradiation of visible light.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with examples are described in detail below.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

The steps used in the present invention for measuring the degradation rate are as follows:

10mg of the nanomaterial/nanocomposite prepared was added to 40mL of CIP solution (10mg/L), and the mixture was stirred without turning on the lamp until an adsorption-desorption equilibrium was established. Then, an 800W xenon lamp (plus an ultraviolet filter (>400nm)) was used as the light source in the catalytic reaction. 3mL of the solution was collected for 30min each and centrifuged, and then the concentration of the supernatant was measured by a UV-visible spectrophotometer (200-800 nm).

Wherein, C₀And C_tThe CIP concentrations are given at reaction times 0 and t, respectively.

The solution containing zinc ions used in the present invention is zinc acetate.

Sodium molybdate dihydrate (Na) used in the examples of the present invention₂MoO₄·2H₂O), zinc acetate dihydrate (Zn (CH)₃COO)₂·2H₂O), bismuth nitrate pentahydrate (Bi (NO)₃)₃·5H₂O), ethanol (C)₂H₆O), ethylene glycol (C)₂H₆O₂) And sodium hydroxide (NaOH) were purchased from the national pharmaceutical group chemical reagents, Inc. (China), and were analytically pure unless otherwise specified.

The Graphite Oxide (GO) used in the examples of the present invention was prepared by a modified Hummer process.

Comparative example 1:

weighing 0.87g of bismuth nitrate and 0.24g of sodium molybdate in 20mL of ethylene glycol, stirring vigorously, then adding 0.044g of zinc acetate, and stirring for 2 hours to obtain a mixed solution;

regulating the pH of the mixed solution to be neutral by using 5M NaOH, stirring for 2h, and finally carrying out solvothermal reaction at the reaction condition of 160 ℃ for 20 h;

taking out the hydrothermal kettle, carrying out suction filtration, washing and drying to obtain Zn_0.1Bi_1.9MoO₆And (3) nano materials.

Prepared Zn_0.1Bi_1.9MoO₆The nano material degrades ciprofloxacin in water under visible light to measure the photocatalytic activity of the nano material, and the degradation rate of ciprofloxacin within 2h is found to be over 51 percent.

Comparative example 2:

0.49g of graphite oxide is put into 40mL of deionized water and subjected to ultrasonic treatment to be uniformly dispersed;

weighing 0.87g of bismuth nitrate and 0.24g of sodium molybdate in 20mL of ethylene glycol, violently stirring, dropwise adding the bismuth nitrate and the sodium molybdate into graphite oxide, and stirring for 2 hours to obtain a mixed solution;

regulating the pH of the mixed solution to be neutral by using 5M NaOH, stirring for 2h, and finally carrying out solvothermal reaction at the reaction condition of 160 ℃ for 20 h;

taking out the hydrothermal kettle, and performing suction filtration, washing and drying to obtain Bi₂MoO₆/RGO₅A nanocomposite material.

The prepared Bi₂MoO₆/RGO₅The nano composite material degrades ciprofloxacin in water under visible light to measure the photocatalytic activity of the ciprofloxacin, and the degradation rate of the ciprofloxacin within 2h is found to be over 44%.

Comparative example 3:

weighing 0.87g of bismuth nitrate and 0.24g of sodium molybdate in 20mL of ethylene glycol, and stirring for 2 hours to obtain a mixed solution;

regulating the pH of the mixed solution to be neutral by using 5M NaOH, stirring for 2h, and finally carrying out solvothermal reaction at the reaction condition of 160 ℃ for 20 h;

taking out the hydrothermal kettle, and performing suction filtration, washing and drying to obtain Bi₂MoO₆And (3) nano materials.

The prepared Bi₂MoO₆The nano material degrades ciprofloxacin in water under visible light to measure the photocatalytic activity of the nano material, and the degradation rate of ciprofloxacin within 2h is found to be over 26%.

Example 1:

weighing graphite oxide with different masses in 40mL of deionized water and carrying out ultrasonic treatment to uniformly disperse the graphite oxide;

weighing 0.87g of bismuth nitrate and 0.24g of sodium molybdate in 20mL of ethylene glycol, violently stirring, and dropwise adding into an oxidized graphite solution; then adding 0.044g of zinc acetate, and stirring for 2 hours to obtain a mixed solution;

regulating the pH of the mixed solution to be neutral by using 5M NaOH, stirring for 2h, and finally carrying out solvothermal reaction at the reaction condition of 160 ℃ for 20 h;

taking out the hydrothermal kettle, carrying out suction filtration, washing and drying to obtain Zn_0.1Bi_1.9MoO₆/RGO_nA nanocomposite material. Different nanocomposites were tested for their photocatalytic activity by degrading ciprofloxacin in water under visible light, with specific results as shown in table 1.

Table 1 ciprofloxacin degradation rates within 2h for different nanocomposites.

As can be seen from the data in table 1 and comparative example 1, the addition of graphite oxide can increase the specific surface area of the catalyst, expose more active sites, and inhibit the recombination of photogenerated carriers. However, the addition is too little, the improvement of the degradation rate is not obvious, and a better experimental effect is not achieved; when the amount of the added graphene is too large and the graphene loading exceeds 5%, the degradation rate tends to decrease, probably because the excessive graphene causes agglomeration and thus active sites to decrease.

Example 2:

weighing 0.49g of graphite oxide in 40mL of deionized water and carrying out ultrasonic treatment to uniformly disperse the graphite oxide;

weighing 0.87g of bismuth nitrate and 0.24g of sodium molybdate in 20mL of ethylene glycol, violently stirring, and dropwise adding into an oxidized graphite solution; adding zinc acetate with different mass, and stirring for 2h to obtain a mixed solution;

regulating the pH of the mixed solution to be neutral by using 5M NaOH, stirring for 2h, and finally carrying out solvothermal reaction at the reaction condition of 160 ℃ for 20 h;

taking out the hydrothermal kettle, carrying out suction filtration, washing and drying to obtain Zn_0.1Bi_1.9MoO₆/RGO_nA nanocomposite material. Different nanocomposites were tested for their photocatalytic activity by degrading ciprofloxacin in water under visible light, with specific results as shown in table 2.

Table 2 ciprofloxacin degradation rates within 2h for different nanocomposites.

When the Zn doping amount is increased from 0 to 0.1, the photocatalytic performance of the composite is in an upward trend. This is probably because the doping of Zn not only can increase the transfer rate of charges, but also can effectively inhibit the recombination of photogenerated electron-hole pairs. When the doping amount of Zn exceeds 0.1, Zn_xBi_2-xMoO₆/RGO₅The photocatalytic activity of (b) is rather decreased. On the one hand, excessive Zn forms an additional recombination center, so that the recombination rate of the photo-generated charges is increased. In another aspect, excess Zn is doped in Bi₂MoO₆Defect positions are introduced into the crystal, so that the distortion is serious, and the photocatalytic activity of the compound is reduced.

Example 3:

weighing graphite oxide in 40mL of deionized water and carrying out ultrasonic treatment to uniformly disperse the graphite oxide;

weighing 0.87g of bismuth nitrate and 0.24g of sodium molybdate in 20mL of ethylene glycol, violently stirring, and dropwise adding into an oxidized graphite solution; adding zinc acetate, and stirring for 2h to obtain a mixed solution;

regulating the pH of the mixed solution to be neutral by using 5M NaOH, stirring for 2h, and finally carrying out solvothermal reaction at the reaction condition of 160 ℃ for 20 h;

taking out the hydrothermal kettle, carrying out suction filtration, washing and drying to obtain Zn_0.1Bi_1.9MoO₆/RGO_nA nanocomposite material. Different nanocomposites were tested for their photocatalytic activity by degrading ciprofloxacin in water under visible light, with specific results as shown in table 2.

Table 2 ciprofloxacin degradation rates within 2h for different nanocomposites.

It is known from the examples and comparative examples that doping of zinc can effectively separate photo-generated electrons and holes, reduce the possibility of recombination of the electrons and the holes, and thus improve the photocatalytic activity of a semiconductor, and addition of graphene oxide can inhibit the agglomeration of bismuth molybdate, so that more active sites are exposed on the surface. As can be seen from table 3, the mass ratio of the two components is 11: 1, the synergistic effect with bismuth molybdate is maximized, so that the degradation rate is highest, and the degradation efficiency is improved.

Zn prepared by the invention_0.1Bi_1.9MoO₆The size of the zinc ion doped composite material is 70-80nm, and when graphene is introduced, Zn is added_0.1Bi_1.9MoO₆/RGO₅The composite size is reduced and the components are uniformly distributed. In the course of photocatalytic degradation, Zn_0.1Bi_1.9MoO₆/RGO₅The complex being favored by electrons from Zn_0.1Bi_1.9MoO₆Transferring to the graphene sheet, increasing the specific surface area of the composite, exposing more active sites and increasing the photocatalytic performance effect of the composite material. In addition, the composite material is doped with zinc, graphene and Bi₂MoO₆Has good synergistic effect, thereby increasing the photocatalytic performance of the composite material.

It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.