Nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material as well as preparation method and application thereof
阅读说明：本技术 一种氧化镍纳米片和钼酸铋纳米纤维异质结光催化材料及其制备方法与应用 (Nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material as well as preparation method and application thereof ) 是由 卢启芳 薛义松 顾洪旭 郭恩言 魏明志 陈德宏 于 2020-12-18 设计创作，主要内容包括：本发明提供了一种氧化镍纳米片和钼酸铋纳米纤维异质结光催化材料及其制备方法与应用,该方法包括步骤：将聚丙烯腈加入N,N-二甲基甲酰胺中,搅拌均匀,得到聚丙烯腈溶胶,经静电纺丝,得聚丙烯腈纤维膜；将五水硝酸铋和钼源加入溶剂中,搅拌均匀,得混合溶液A,之后加入聚丙烯腈纤维膜,进行溶剂热反应；经冷却、过滤、洗涤、干燥、煅烧,得到钼酸铋纳米纤维；将镍源、六亚甲基四胺、柠檬酸钠溶于去离子水中,得混合溶液B,之后加入钼酸铋纳米纤维,进行反应；经冷却、过滤、洗涤、干燥、煅烧,即得。本发明制备的光催化材料可以有效分离和输送光生载流子,具有较高的光催化效率,对四环素等具有良好的光催化降解效果。(The invention provides a nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material as well as a preparation method and application thereof, wherein the method comprises the following steps: adding polyacrylonitrile into N, N-dimethylformamide, stirring uniformly to obtain polyacrylonitrile sol, and performing electrostatic spinning to obtain a polyacrylonitrile fiber membrane; adding bismuth nitrate pentahydrate and a molybdenum source into a solvent, uniformly stirring to obtain a mixed solution A, and then adding a polyacrylonitrile fiber membrane for solvothermal reaction; cooling, filtering, washing, drying and calcining to obtain the bismuth molybdate nano-fiber; dissolving a nickel source, hexamethylenetetramine and sodium citrate in deionized water to obtain a mixed solution B, and then adding bismuth molybdate nano fibers for reaction; cooling, filtering, washing, drying and calcining to obtain the catalyst. The photocatalytic material prepared by the invention can effectively separate and transport photon-generated carriers, has higher photocatalytic efficiency, and has good photocatalytic degradation effect on tetracycline and the like.)
1. A nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material is characterized in that the microscopic morphology of the photocatalytic material is that the nickel oxide nanosheet is loaded on the surface of a bismuth molybdate nanofiber;
the diameter of the bismuth molybdate nanofiber is 100-150nm, the length of the bismuth molybdate nanofiber is 5-20 mu m, and the thickness of the nickel oxide nanosheet is 10-20 nm.
2. The preparation method of the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material of claim 1, comprising the steps of:
(1) adding polyacrylonitrile into N, N-dimethylformamide, uniformly stirring to obtain polyacrylonitrile sol, and performing electrostatic spinning to obtain a polyacrylonitrile fiber membrane;
(2) adding bismuth nitrate pentahydrate and a molybdenum source into a solvent, uniformly stirring to obtain a mixed solution A, then adding the polyacrylonitrile fiber membrane obtained in the step (1) into the mixed solution A, and carrying out solvothermal reaction; after the reaction is finished, cooling, filtering, washing, drying and calcining to obtain the bismuth molybdate nano-fiber;
(3) adding a nickel source, hexamethylenetetramine and sodium citrate into deionized water to obtain a mixed solution B, and then adding the bismuth molybdate nano-fibers obtained in the step (2) for reaction; after the reaction is finished, cooling, filtering, washing, drying and calcining are carried out, so as to obtain the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material.
3. The method for preparing nickel oxide nanosheets and bismuth molybdate nanofiber heterojunction photocatalytic material as claimed in claim 2, wherein the polyacrylonitrile in step (1) has a weight average molecular weight of 15 to 25 ten thousand, preferably 15 ten thousand; the mass ratio of the polyacrylonitrile to the volume of the N, N-dimethylformamide is (0.8-1.0) g: (8-10) mL.
4. The preparation method of the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material as claimed in claim 2, wherein the electrostatic spinning in step (1) is performed under the following process conditions: the temperature is 20-25 ℃, the receiving distance of electrostatic spinning is 10-20cm, the ejection rate is 1.0-1.5mL/h, the voltage is 20-25kV, and the relative humidity is 10-30%.
5. The method for preparing nickel oxide nanosheets and bismuth molybdate nanofiber heterojunction photocatalytic material as claimed in claim 2, wherein in step (2) the molybdenum source is ammonium molybdate or sodium molybdate; the solvent is a mixed solution of ethylene glycol and absolute ethyl alcohol, and the volume ratio of the ethylene glycol to the absolute ethyl alcohol in the mixed solution is 1: (1-2).
6. The method for preparing a nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material as claimed in claim 2, wherein the molar ratio of the Bi element to the Mo element in the mixed solution a in step (2) is 2: 1; the concentration of the bismuth nitrate pentahydrate in the mixed solution A is 0.01-0.02 mmol/mL; the adding amount of the polyacrylonitrile fiber membrane in the mixed solution A is 1-2 mg/mL.
7. The method for preparing nickel oxide nanosheets and bismuth molybdate nanofiber heterojunction photocatalytic materials as claimed in claim 2, wherein the solvothermal reaction in step (2) is carried out at a temperature of 140-180 ℃ for 16-24 h;
the cooling is to naturally cool the reaction solution to room temperature; the washing is to wash the product obtained by filtering for 3-5 times by using deionized water and absolute ethyl alcohol respectively in turn; the drying is to dry the product obtained by washing at 40-60 ℃ for 6-12 h; the calcination temperature is 500-600 ℃, the heating rate is 1-5 ℃/min, and the heat preservation time is 60-120 min.
8. The method for preparing a nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material as claimed in claim 2, wherein the nickel source in step (3) is nickel acetate or nickel nitrate hexahydrate;
the molar ratio of the nickel source to the hexamethylenetetramine is (1-2): 1, preferably 1: 1; the molar ratio of the nickel source to the sodium citrate is (5-15): 1, preferably 10: 1; the concentration of the nickel source in the mixed solution B is 0.002-0.005 mmol/mL;
the molar ratio of the Ni element in the nickel source to the Bi element in the bismuth molybdate nano-fiber is 1: (1-4).
9. The method for preparing the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material as claimed in claim 2, wherein the reaction temperature in step (3) is 70-100 ℃ and the reaction time is 7-12 h;
the cooling is to naturally cool the reaction solution to room temperature; the washing is to wash the product obtained by filtering for 3-5 times by using deionized water and absolute ethyl alcohol respectively in turn; the drying is to dry the product obtained by washing at 40-60 ℃ for 6-12 h; the calcination temperature is 300-400 ℃, the heating rate is 1-5 ℃/min, and the heat preservation time is 60-120 min.
10. The use of the nickel oxide nanosheets and the bismuth molybdate nanofiber heterojunction photocatalytic material of claim 1 for photocatalytic degradation of tetracycline.
Technical Field
The invention relates to a nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material as well as a preparation method and application thereof, and belongs to the technical field of inorganic photocatalytic materials.
Background
Since the 21 st century, the industrialization process is accelerating, the living standard of people is increasing, and the problems of energy crisis and environmental pollution caused by the improvement are becoming serious. Among them, water pollution seriously damages ecological balance and threatens human living environment and life health, so that control and treatment of water pollution become one of the major problems to be solved urgently in human society. The semiconductor photocatalysis technology has the advantages of low cost, environmental protection, energy conservation, high efficiency and the like, and has wide application prospect in the aspect of treating water pollution.
TiO semiconductor has been found since Showa in 19722Since electrodes are capable of photolyzing water to generate oxygen and hydrogen under irradiation of ultraviolet light, various TiO-based electrodes have been reported2But due to TiO2The forbidden band width of the photocatalyst is large, and the photocatalyst can only absorb ultraviolet light which accounts for about 4% of the solar spectrum, so that the utilization rate of sunlight is low, and the practical application of the photocatalyst in the field of photocatalysis is limited. In order to fully utilize visible light, which is a major part of sunlight, it is necessary to develop a photocatalyst having a visible light response.
Bi2MoO6The photocatalyst is a typical Aurivillius type layered compound, has a proper band gap and good visible light absorption capacity, and is an ideal photocatalyst capable of removing pollutants by photocatalysis by using visible light. But Bi of a single component2MoO6There are also some disadvantages: such as low quantum yield,The photo-generated electron-hole pairs are easy to recombine, the carrier transmission efficiency is low, and the like, and the defects limit the photocatalytic activity and are not beneficial to the practical application, so that the photo-generated electron-hole pairs need to be modified. The conventional modification methods include morphology control (see: Journal of Power Sources,2016,331,481-486), heterojunction construction (see: Applied Catalysis B: Environmental,2019,250,313-324), ion doping (see: Journal of Physics and Chemistry of Solids,2019,129,209-216), among others, wherein the reports on heterojunction construction are the most. For example: chinese patent document CN104096558A provides a ZnO/Bi2MoO6The composite photocatalyst is prepared with zinc acetate, bismuth nitrate and sodium molybdate as material and through mechanical stirring to mix homogeneously, regulating pH value of the solution and hydrothermal reaction to prepare ZnO/Bi in one step2MoO6A composite photocatalyst, ZnO as a wide bandgap n-type semiconductor, and n-type Bi2MoO6An n-n heterojunction is formed which has a relatively low efficiency in separating photogenerated carriers. Chinese patent document CN111135838A provides a Bi2MoO6And Co (OH)2Constructing a heterostructure-forming composite, said sheet-like Co (OH)2And spherical Bi2MoO6In the process of solvothermal reaction, the Bi in the heterogeneous structure is jointly assembled into a spherical structure to form a heterogeneous structure2MoO6The size of the ball and the size of the ball after forming the heterojunction reach the micron level and have no nanometer effect.
NiO as a wide band gap semiconductor has excellent electronic and optical properties and high chemical stability, can be used for photocatalytic degradation of pollutants, but has a larger band gap so that the NiO only responds to ultraviolet light, and the construction of a heterojunction is the simplest and most effective method for widening the photoresponse range.
Therefore, by constructing NiO nano-sheet and Bi2MoO6The nanofiber heterojunction can widen the photoresponse range, can form a built-in electric field, and improves the separation efficiency and the mobility of a photon-generated carrier, so that the overall photocatalytic efficiency is improved. In addition, the two-dimensional NiO nano-sheet has a large surface area, and can effectively adsorb pollutants, so that the pollutant degradation efficiency is improved. So far, there is little about NiO/Bi2MoO6The heterojunction is reported. The invention is therefore proposed.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material as well as a preparation method and application thereof. The bismuth molybdate nano-fiber in the photocatalytic material has a low-temperature phase and a high-temperature phase at the same time to form an in-phase heterojunction, so that a photo-generated carrier can be effectively separated, and the separation and conveying efficiency of the photo-generated carrier can be further improved after the nickel oxide nano-sheet and the bismuth molybdate nano-fiber are compounded, so that more photo-generated electrons and holes react with pollutants, and the photocatalytic material has excellent photocatalytic performance.
Description of terms:
spinning receiving distance: distance of the electrospinning needle to the receiving device.
Room temperature: having a meaning well known in the art, meaning 25. + -. 5 ℃.
The technical scheme of the invention is as follows:
the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material is characterized in that the nickel oxide nanosheet is loaded on the surface of a bismuth molybdate nanofiber in a microscopic form.
According to the invention, the diameter of the bismuth molybdate nano-fiber is 100-150nm, the length of the bismuth molybdate nano-fiber is 5-20 μm, and the thickness of the nickel oxide nano-sheet is 10-20 nm.
According to the invention, the preparation method of the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material comprises the following steps:
(1) adding polyacrylonitrile into N, N-dimethylformamide, uniformly stirring to obtain polyacrylonitrile sol, and performing electrostatic spinning to obtain a polyacrylonitrile fiber membrane;
(2) adding bismuth nitrate pentahydrate and a molybdenum source into a solvent, uniformly stirring to obtain a mixed solution A, then adding the polyacrylonitrile fiber membrane obtained in the step (1) into the mixed solution A, and carrying out solvothermal reaction; after the reaction is finished, cooling, filtering, washing, drying and calcining to obtain the bismuth molybdate nano-fiber;
(3) adding a nickel source, hexamethylenetetramine and sodium citrate into deionized water to obtain a mixed solution B, and then adding the bismuth molybdate nano-fibers obtained in the step (2) for reaction; after the reaction is finished, cooling, filtering, washing, drying and calcining are carried out, so as to obtain the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material.
Preferably, according to the invention, the polyacrylonitrile in the step (1) has a weight average molecular weight of 15 to 25 ten thousand; more preferably 15 ten thousand.
Preferably, according to the invention, the mass of polyacrylonitrile to volume of N, N-dimethylformamide in step (1) is (0.8-1.0) g: (8-10) mL.
According to the present invention, the electrostatic spinning in step (1) preferably comprises the following process conditions: the temperature is 20-25 ℃, the receiving distance of electrostatic spinning is 10-20cm, the ejection rate is 1.0-1.5mL/h, the voltage is 20-25kV, and the relative humidity is 10-30%.
Preferably, according to the present invention, the molybdenum source in step (2) is ammonium molybdate or sodium molybdate.
According to the present invention, preferably, the solvent in the step (2) is a mixed solution of ethylene glycol and absolute ethyl alcohol, and the volume ratio of the ethylene glycol to the absolute ethyl alcohol in the mixed solution is 1: (1-2).
Preferably, in the step (2), the molar ratio of the Bi element to the Mo element in the mixed solution a is 2: 1; the concentration of the bismuth nitrate pentahydrate in the mixed solution A is 0.01-0.02 mmol/mL.
According to the invention, the adding amount of the polyacrylonitrile fiber membrane in the mixed solution A in the step (2) is preferably 1-2 mg/mL.
According to the invention, the temperature of the solvothermal reaction in the step (2) is 140-180 ℃, and the reaction time is 16-24 h.
According to the invention, the cooling in the step (2) is preferably to naturally cool the reaction solution to room temperature; the washing is to wash the product obtained by filtering for 3-5 times by using deionized water and absolute ethyl alcohol respectively in turn; the drying is to dry the product obtained by washing at 40-60 ℃ for 6-12 h; the calcination temperature is 500-600 ℃, the heating rate is 1-5 ℃/min, and the heat preservation time is 60-120 min.
Preferably according to the invention, the nickel source in step (3) is nickel acetate or nickel nitrate hexahydrate.
Preferably according to the invention, the molar ratio of the nickel source to hexamethylenetetramine in step (3) is (1-2): 1, more preferably 1: 1; the molar ratio of the nickel source to the sodium citrate is (5-15): 1, more preferably 10: 1; the concentration of the nickel source in the mixed solution B is 0.002-0.005 mmol/mL.
Preferably, in step (3), the molar ratio of the Ni element in the nickel source to the Bi element in the bismuth molybdate nanofibers is 1: (1-4).
According to the invention, the reaction temperature in the step (3) is 70-100 ℃, and the reaction time is 7-12 h.
According to the invention, the cooling in the step (3) is preferably to naturally cool the reaction solution to room temperature; the washing is to wash the product obtained by filtering for 3-5 times by using deionized water and absolute ethyl alcohol respectively in turn; the drying is to dry the product obtained by washing at 40-60 ℃ for 6-12 h; the calcination temperature is 300-400 ℃, the heating rate is 1-5 ℃/min, and the heat preservation time is 60-120 min.
According to the invention, the application of the nickel oxide nanosheet and the bismuth molybdate nanofiber heterojunction photocatalytic material is used for photocatalytic degradation of tetracycline.
All chemicals used in the present invention were analytically pure and were not further processed.
The invention has the following technical characteristics and beneficial effects:
1. the bismuth molybdate nano-fibers in the photocatalytic material prepared by the invention have a low-temperature phase and a high-temperature phase at the same time, form a homogeneous and heterogeneous phase, and can effectively separate photon-generated carriers, so that the photocatalytic activity of the material is improved, and the performance of the material is better than that of single-phase bismuth molybdate obtained by an electrostatic spinning method; the p-type nickel oxide nanosheets and the n-type bismuth molybdate nanofibers form a p-n heterostructure, so that the separation and conveying efficiency of photo-generated carriers can be further improved, more photo-generated electrons and holes are reacted with pollutants, the photocatalytic activity of the material is further improved, and the photocatalytic efficiency is enhanced, so that the photocatalytic material prepared by the method has excellent photocatalytic performance, the degradation efficiency of the photocatalytic degradation of tetracycline can reach 90%, and the photocatalytic degradation of tetracycline is better than that of bismuth molybdate nanofibers.
2. The nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material prepared by the method is uniform in shape, good in continuity and easy to control; the prepared nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material is green and pollution-free, can be recycled by a sedimentation method, and further reduces the cost.
3. The preparation method is simple, the process equipment is simple, and the operation is easy.
Drawings
Fig. 1 is an X-ray diffraction spectrum of the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material prepared in example 1 and the bismuth molybdate nanofiber prepared in example 1.
FIG. 2 is a scanning electron micrograph of the bismuth molybdate nanofibers prepared in example 1; wherein a is a low power Scanning Electron Microscope (SEM) photograph; and b is a high-power Scanning Electron Microscope (SEM) picture.
FIG. 3 is a transmission electron micrograph of the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material prepared in example 1; wherein a is a low power Transmission Electron Microscope (TEM) photograph; b is a high power Transmission Electron Microscope (TEM) photograph.
Fig. 4 is an absorbance curve of photocatalytic degradation of tetracycline by applying the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material prepared in example 1 of application example 1 under simulated sunlight.
Fig. 5 is a graph showing the absorbance of the bismuth molybdate nanofibers prepared in comparative example 1 in application example 1 in simulated sunlight for photocatalytic oxidation degradation of tetracycline.
Fig. 6 is a graph of degradation efficiency of a triple cycle test for degrading tetracycline under simulated sunlight by applying the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material prepared in example 1 of application example 1.
Fig. 7 is a graph of degradation efficiency of the bismuth molybdate nanofiber prepared in comparative example 1 in application example 1 in a simulated three-cycle solar degradation tetracycline degradation test.
Detailed Description
The invention will now be further illustrated by means of specific examples and figures, without however limiting the scope of the invention as claimed.
The raw materials used in the examples are conventional raw materials, and the equipment used is conventional equipment, all of which are commercially available.
The electrostatic spinning device adopts a common electrostatic spinning machine on the market; the propeller is a conventional plastic syringe;
the Polyacrylonitrile (PAN) used in the examples had an average weight average molecular weight of 15 ten thousand.
Example 1
Nickel oxide nanosheet and bismuth molybdate nanofiber (NiO/Bi)2MoO6) The preparation method of the heterojunction photocatalytic material comprises the following steps:
(1) weighing 1g of Polyacrylonitrile (PAN), adding the Polyacrylonitrile (PAN) into a beaker containing 9mL of N, N-Dimethylformamide (DMF), and uniformly stirring to obtain polyacrylonitrile sol; and adding the polyacrylonitrile sol into a plastic injector with a stainless steel needle head, spraying the polyacrylonitrile sol into a receiving plate, wherein the receiving distance between the stainless steel needle head of the injector and the receiving plate is 15cm, the spraying speed of the polyacrylonitrile sol is 1.0mL/h, the voltage is 20kV, the electrostatic spinning temperature is controlled at 25 ℃, and the relative humidity is 20%, so that the polyacrylonitrile fiber membrane is obtained.
(2) 0.028mmol ammonium molybdate (molecular formula is (NH))4)6Mo7O24·4H2O) and 0.4mmol of bismuth nitrate pentahydrate are added into a mixed solvent consisting of 10mL of ethylene glycol and 20mL of absolute ethyl alcohol, the mixture is uniformly stirred, the obtained mixed solution A is poured into a reaction kettle, 40mg of polyacrylonitrile fiber membrane prepared in the step (1) is added, the mixture reacts for 24 hours at 160 ℃, then the mixture is naturally cooled to room temperature and filtered, solid products obtained by filtering are respectively washed for 5 times by deionized water and absolute ethyl alcohol, and then the products obtained by washing are dried for 12 hours in a drying oven at 60 ℃; then placing the dried product in a high temperature furnace, heating to 500 ℃ at the heating rate of 1 ℃/min, and preserving the temperature for 120min, namelyObtaining bismuth molybdate (Bi)2MoO6) And (3) nano fibers.
(3) Weighing 0.25mmol of nickel acetate, 0.25mmol of Hexamethylenetetramine (HMT) and 0.025mmol of sodium citrate, adding the nickel acetate, the Hexamethylenetetramine (HMT) and the sodium citrate into a round-bottom flask containing 60mL of deionized water to obtain a mixed solution B, and adding 0.125mmol of Bi prepared in the step (2)2MoO6The preparation method comprises the following steps of (1) reacting nano fibers at 90 ℃ for 8 hours, naturally cooling to room temperature, filtering, washing solid products obtained by filtering with deionized water and absolute ethyl alcohol for 5 times respectively, and drying the washed products in a drying oven at 60 ℃ for 12 hours to obtain solid samples; placing the dried solid sample in a high-temperature furnace, raising the temperature to 300 ℃ at the heating rate of 2 ℃/min, and preserving the temperature for 120min to obtain the nickel oxide nano-sheet and the bismuth molybdate nano-fiber (NiO/Bi)2MoO6) A heterojunction photocatalytic material.
Bismuth molybdate (Bi) prepared in this example2MoO6) Nanofibers, and nickel oxide nanosheets and bismuth molybdate nanofibers (NiO/Bi)2MoO6) The X-ray diffraction pattern (XRD) of the heterojunction photocatalytic material is shown in fig. 1. As can be seen from FIG. 1, Bi2MoO6Bi appears in the sample2MoO6The low temperature phase (JCPDS No.21-0102) and the high temperature phase (JCPDS No.22-0112) form a homogeneous heterogeneous structure; NiO/Bi2MoO6Bi appears in the sample2MoO6The low temperature phase (JCPDS No.21-0102) and the high temperature phase (JCPDS No.22-0112) of (4) constitute a homogeneous heterogeneous structure, and a diffraction peak of NiO (JCPDS No.73-1519) appears.
Bismuth molybdate (Bi) prepared in this example2MoO6) The Scanning Electron Microscope (SEM) of the nanofibers is shown in fig. 2. As can be seen from FIG. 2, Bi2MoO6The diameter of the nano-fiber is 100-150nm, and the fiber has uniform appearance and good continuity.
Nickel oxide nanosheets and bismuth molybdate nanofibers (NiO/Bi) prepared in this example2MoO6) A Transmission Electron Microscope (TEM) of the heterojunction photocatalytic material is shown in fig. 3. As can be seen from FIG. 3, the NiO nano-sheets successfully grow on the surface of the bismuth molybdate nanofiber, the morphology is uniform and continuous, and the NiO nano-sheetsThe thickness of the bismuth molybdate nano-fiber is 10-20nm, and the diameter of the bismuth molybdate nano-fiber is 100-150 nm.
Example 2
Nickel oxide nanosheet and bismuth molybdate nanofiber (NiO/Bi)2MoO6) The preparation method of the heterojunction photocatalytic material comprises the following steps:
(1) weighing 1g of Polyacrylonitrile (PAN), adding the Polyacrylonitrile (PAN) into a beaker containing 9mL of N, N-Dimethylformamide (DMF), and uniformly stirring to obtain polyacrylonitrile sol; and adding the polyacrylonitrile sol into a plastic injector with a stainless steel needle head, spraying the polyacrylonitrile sol into a receiving plate, wherein the receiving distance between the stainless steel needle head of the injector and the receiving plate is 15cm, the spraying speed of the polyacrylonitrile sol is 1.0mL/h, the voltage is 20kV, the electrostatic spinning temperature is controlled at 25 ℃, and the relative humidity is 20%, so that the polyacrylonitrile fiber membrane is obtained.
(2) Weighing 0.2mmol of sodium molybdate and 0.4mmol of bismuth nitrate pentahydrate, adding the sodium molybdate and the bismuth nitrate pentahydrate into a mixed solvent consisting of 10mL of ethylene glycol and 20mL of absolute ethyl alcohol, uniformly stirring, pouring the obtained mixed solution A into a reaction kettle, adding 40mg of the polyacrylonitrile fiber membrane prepared in the step (1), reacting at 180 ℃ for 24h, naturally cooling to room temperature, filtering, washing solid products obtained by filtering with deionized water and absolute ethyl alcohol for 5 times respectively, and then drying the washed products in a drying oven at 60 ℃ for 12 h; then the dried product is put into a high temperature furnace, then the temperature is raised to 500 ℃ at the heating rate of 2 ℃/min, and the temperature is preserved for 120min, thus obtaining the bismuth molybdate (Bi)2MoO6) And (3) nano fibers.
(3) Weighing 0.25mmol of nickel nitrate hexahydrate, 0.25mmol of Hexamethylenetetramine (HMT) and 0.025mmol of sodium citrate, adding the nickel nitrate hexahydrate, the Hexamethylenetetramine (HMT) and the sodium citrate into a round-bottom flask containing 60mL of deionized water to obtain a mixed solution B, and adding 0.125mmol of Bi prepared in the step (2)2MoO6The preparation method comprises the following steps of (1) reacting nano fibers at 90 ℃ for 10 hours, naturally cooling to room temperature, filtering, washing solid products obtained by filtering with deionized water and absolute ethyl alcohol for 5 times respectively, and drying the washed products in a drying oven at 60 ℃ for 12 hours to obtain solid samples; placing the dried solid sample in a high temperature furnace, heating to 300 deg.C at a heating rate of 1 deg.C/min, and maintaining for 120min to obtain the final productTo nickel oxide nanosheets and bismuth molybdate nanofibers (NiO/Bi)2MoO6) A heterojunction photocatalytic material.
Example 3
Nickel oxide nanosheet and bismuth molybdate nanofiber (NiO/Bi)2MoO6) The preparation method of the heterojunction photocatalytic material comprises the following steps:
(1) weighing 1g of Polyacrylonitrile (PAN), adding the Polyacrylonitrile (PAN) into a beaker containing 10mL of N, N-Dimethylformamide (DMF), and uniformly stirring to obtain polyacrylonitrile sol; and adding the polyacrylonitrile sol into a plastic injector with a stainless steel needle head, spraying the polyacrylonitrile sol into a receiving plate, wherein the receiving distance between the stainless steel needle head of the injector and the receiving plate is 15cm, the spraying speed of the polyacrylonitrile sol is 1.0mL/h, the voltage is 20kV, the electrostatic spinning temperature is controlled at 25 ℃, and the relative humidity is 20%, so that the polyacrylonitrile fiber membrane is obtained.
(2) Weighing 0.25mmol of sodium molybdate and 0.5mmol of bismuth nitrate pentahydrate, adding the sodium molybdate and the bismuth nitrate pentahydrate into a mixed solvent consisting of 10mL of ethylene glycol and 20mL of absolute ethyl alcohol, uniformly stirring, pouring the obtained mixed solution A into a reaction kettle, adding 50mg of the polyacrylonitrile fiber membrane prepared in the step (1), reacting at 160 ℃ for 24h, naturally cooling to room temperature, filtering, washing solid products obtained by filtering with deionized water and absolute ethyl alcohol for 5 times respectively, and then drying the washed products in a drying oven at 60 ℃ for 12 h; then the dried product is put into a high temperature furnace, then the temperature is raised to 500 ℃ at the heating rate of 1 ℃/min, and the temperature is preserved for 120min, thus obtaining the bismuth molybdate (Bi)2MoO6) And (3) nano fibers.
(3) Weighing 0.25mmol of nickel nitrate hexahydrate, 0.25mmol of Hexamethylenetetramine (HMT) and 0.025mmol of sodium citrate, adding the nickel nitrate hexahydrate, the Hexamethylenetetramine (HMT) and the sodium citrate into a round-bottom flask containing 60mL of deionized water to obtain a mixed solution B, and adding 0.25mmol of Bi prepared in the step (2)2MoO6The preparation method comprises the following steps of (1) reacting nano fibers at 100 ℃ for 12 hours, naturally cooling to room temperature, filtering, washing solid products obtained by filtering with deionized water and absolute ethyl alcohol for 5 times respectively, and drying the washed products in a drying oven at 60 ℃ for 12 hours to obtain solid samples; placing the dried solid sample in a high temperature furnace, and then heating at the speed of 2 ℃/minRaising the speed to 300 ℃, and preserving the heat for 120min to obtain the nickel oxide nano-sheet and the bismuth molybdate nano-fiber (NiO/Bi)2MoO6) A heterojunction photocatalytic material.
Example 4
Nickel oxide nanosheet and bismuth molybdate nanofiber (NiO/Bi)2MoO6) The preparation method of the heterojunction photocatalytic material comprises the following steps:
(1) weighing 0.8g of Polyacrylonitrile (PAN), adding the Polyacrylonitrile (PAN) into a beaker containing 8mL of N, N-Dimethylformamide (DMF), and uniformly stirring to obtain polyacrylonitrile sol; and adding the polyacrylonitrile sol into a plastic injector with a stainless steel needle head, spraying the polyacrylonitrile sol into a receiving plate, wherein the receiving distance between the stainless steel needle head of the injector and the receiving plate is 15cm, the spraying speed of the polyacrylonitrile sol is 1.0mL/h, the voltage is 20kV, the electrostatic spinning temperature is controlled at 25 ℃, and the relative humidity is 20%, so that the polyacrylonitrile fiber membrane is obtained.
(2) 0.021mmol ammonium molybdate (molecular formula is (NH)4)6Mo7O24·4H2O) and 0.3mmol of bismuth nitrate pentahydrate are added into a mixed solvent consisting of 15mL of ethylene glycol and 15mL of absolute ethyl alcohol, the mixture is uniformly stirred, the obtained mixed solution A is poured into a reaction kettle, 30mg of the polyacrylonitrile fiber membrane prepared in the step (1) is added, the mixture reacts for 20 hours at the temperature of 140 ℃, then the mixture is naturally cooled to the room temperature and filtered, solid products obtained by filtering are respectively washed for 5 times by deionized water and absolute ethyl alcohol, and then the products obtained by washing are dried for 12 hours in a drying oven at the temperature of 60 ℃; then the dried product is put into a high temperature furnace, then the temperature is raised to 500 ℃ at the heating rate of 1 ℃/min, and the temperature is preserved for 60min, thus obtaining the bismuth molybdate (Bi)2MoO6) And (3) nano fibers.
(3) Weighing 0.15mmol of nickel acetate, 0.15mmol of Hexamethylenetetramine (HMT) and 0.015mmol of sodium citrate, adding the nickel acetate, the Hexamethylenetetramine (HMT) and the sodium citrate into a round-bottom flask containing 60mL of deionized water to obtain a mixed solution B, and then adding 0.075mmol of Bi prepared in the step (2)2MoO6Nano-fiber, reacting at 70 deg.C for 7h, naturally cooling to room temperature, filtering, washing the solid product with deionized water and anhydrous ethanol for 5 times, and drying at 60 deg.CDrying in a drying oven for 12h to obtain a solid sample; placing the dried solid sample in a high-temperature furnace, raising the temperature to 300 ℃ at the heating rate of 1 ℃/min, and preserving the temperature for 60min to obtain the nickel oxide nano-sheet and bismuth molybdate (NiO/Bi)2MoO6) A nanofiber heterojunction photocatalytic material.
Comparative example 1
The bismuth molybdate (Bi) prepared in example 12MoO6) The nanofibers are the photocatalytic material of comparative example 1.
Application example 1
Photocatalytic degradation of tetracyclines
Nickel oxide nanosheets and bismuth molybdate nanofibers (NiO/Bi) prepared in example 12MoO6) The heterojunction photocatalytic material and the bismuth molybdate nano-fiber prepared in the comparative example 1 are applied to a tetracycline photocatalytic degradation experiment, the used simulated light source is an 800W xenon lamp, the concentration of a tetracycline solution is 10mg/L, and the steps are as follows:
40mg of the photocatalysts (NiO/Bi) obtained in example 1 and comparative example 1 were added2MoO6、Bi2MoO6Nano-fiber) are respectively dispersed into 40mL of 10mg/L tetracycline solution, and then the tetracycline solution is placed in a dark box for stirring and adsorption for 30min to reach adsorption balance; then, a xenon lamp simulating a sunlight source is turned on to irradiate the solution, 5mL of the solution is taken every 30min, the photocatalyst is separated by a centrifuge (8000rpm,5min), and the supernatant is taken and the absorbance is tested by a UV-2550 spectrophotometer. After the reaction is completed, the catalyst is recovered.
FIG. 4 shows nickel oxide nanosheets and bismuth molybdate nanofibers (NiO/Bi) prepared in example 12MoO6) An absorbance curve of the heterojunction photocatalytic material for photocatalytic degradation of tetracycline in simulated sunlight, and fig. 5 is an absorbance curve of the bismuth molybdate nanofiber prepared in comparative example 1 for photocatalytic degradation of tetracycline in simulated sunlight, with a detection wavelength of 200-500 nm. Comparing fig. 4 and 5, it can be seen that the nickel oxide nanosheets and the bismuth molybdate nanofiber heterojunction photocatalytic material prepared in example 1 have an excellent photocatalytic degradation effect on tetracycline.
Application example 2
The photocatalytic materials prepared in example 1 and comparative example 1 were subjected to a cycle performance test for photocatalytic degradation of tetracycline.
The degradation efficiency graph of the nickel oxide nanosheet and the bismuth molybdate nanofiber heterojunction photocatalytic material prepared in example 1 to tetracycline repeatedly recycled under simulated sunlight for three times is shown in fig. 6; the graph of the degradation efficiency of the bismuth molybdate nanofiber prepared in the comparative example 1 to tetracycline after repeated cyclic utilization under simulated sunlight for three times is shown in fig. 7.
As can be seen from fig. 6 and 7, the first degradation efficiency of the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material prepared in example 1 is as high as 90%, and after three times of cyclic utilization, the photocatalytic efficiency of the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material prepared in example 1 is 89%; the first degradation efficiency of the bismuth molybdate nanofiber prepared in the comparative example 1 is 51%, after the bismuth molybdate nanofiber prepared in the example is recycled for three times, the photocatalytic efficiency of the bismuth molybdate nanofiber is 47.7%, and the degradation efficiency of the sample is reduced by 3.3%.
It can be seen through comparison that the nickel oxide nanosheet and bismuth molybdate nanofiber heterojunction photocatalytic material prepared in example 1 has a more excellent photocatalytic degradation effect on tetracycline, has good stability, can be recycled, and greatly reduces production cost.
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