阅读说明：本技术 高效可见光驱动复合纳米催化剂及其制备方法和用途 (High-efficiency visible light driven composite nano catalyst and preparation method and application thereof ) 是由 崔艳萍 曹俊港 吴若杰 叶骞 多雪文 王海力 于 2020-07-27 设计创作，主要内容包括：本发明公开了一种高效可见光驱动复合纳米催化剂,还公开了一种高效可见光驱动复合纳米催化剂的制备方法,以模板法脉冲电沉积技术为手段,借助不同孔径的PC膜作为纳米线的生长模板,在不同配比的络合剂中,脉冲电沉积目标金属材料,完成纳米线成长,将模板移除后,氯化纳米线,在纳米线表面形成AgCl外壳,最终得到可磁性分离的复合纳米催化剂,还提供一种高效可见光驱动复合纳米催化剂在三价砷预氧化、降解有机物、杀菌处理领域中的用途。本发明借助零价铁的顺磁性,合成磁性光催化纳米材料,克服铁氧化物磁性纳米材料易自团聚的缺点。(The invention discloses a high-efficiency visible light driven composite nano catalyst and a preparation method thereof, wherein a template method pulse electrodeposition technology is used as a means, PC films with different apertures are used as growth templates of nanowires, target metal materials are subjected to pulse electrodeposition in complexing agents with different proportions to finish nanowire growth, after the templates are removed, the nanowires are chlorinated, AgCl shells are formed on the surfaces of the nanowires, and finally the magnetically separable composite nano catalyst is obtained. The invention synthesizes the magnetic photocatalysis nano material by virtue of paramagnetism of zero-valent iron, and overcomes the defect that the iron oxide magnetic nano material is easy to self-agglomerate.)

1. The efficient visible light driven composite nano catalyst is characterized by comprising a metal nanowire core and an AgX shell coated on the metal nanowire core, wherein the metal nanowire core is one of Fe-Ag segmented nanowires and Fe nanowires, and X is one of Cl, Br and I.

2. A preparation method of a high-efficiency visible light driven composite nano catalyst is characterized in that a template method is adopted for pulse electrodeposition to prepare metal nanowires, after a template is removed, AgCl shells are coated on the surfaces of the metal nanowires, and the composite nano catalyst is obtained.

3. The method for preparing the high efficiency visible light driven composite nanocatalyst of claim 2, wherein the electrodeposition solution used for electrodeposition is one or both of an Ag electrodeposition electrolyte containing thiourea and an Fe electrodeposition electrolyte containing sodium citrate.

4. The method for preparing the high-efficiency visible light driven composite nano catalyst according to claim 3, wherein the concentration of thiourea in the Ag electrodeposition electrolyte is 0.1-0.45 mol/L, and the concentration of the silver-containing substance is 2.0-7.0 mmol/L; the concentration of sodium citrate in the Fe electrodeposition electrolyte is 0.1-0.5 mol/L, and the concentration of ferrous sulfate is 0.2-0.5 mol/L.

5. The method for preparing the high-efficiency visible light driven composite nano catalyst as claimed in claim 2, wherein the electrodeposition is performed by adopting a three-electrode system connected with an electrochemical workstation, a PC template is taken as a working electrode, a platinum mesh electrode is taken as a counter electrode, a saturated calomel electrode is taken as a reference electrode, and the electrolytic cell is composed of polytetrafluoroethylene capable of fixedly replacing a PC membrane.

6. The method for preparing the high-efficiency visible light driven composite nano catalyst according to claim 3, wherein after the Ag electrodeposition electrolyte is added, the electrodeposition pulse period parameters are applied as follows: t is t_off＝0～20s，I＝-2～0mA，t_onThe deposition time is 10-40 s and 0-90 min.

7. The method for preparing the high-efficiency visible light driven composite nano catalyst according to claim 3, wherein after adding the Fe electrodeposition electrolyte, the electrodeposition pulse period parameters are applied: t is t_off＝0～20s，I＝-4.5～0mA，t_onThe deposition time is 0-40 s and 0-30 min.

8. The preparation method of the efficient visible light driven composite nano catalyst as claimed in claim 2, wherein after the electrodeposition is completed, the PC membrane on the PC template is taken out, repeatedly washed with deionized water, dissolved with dichloromethane, and placed for 2-12 h after being subjected to ultrasonic treatment for 10-30 s, so that the dispersed and independent metal nanowires can be obtained.

9. The preparation method of the high-efficiency visible light driven composite nano catalyst as claimed in claim 2, wherein the specific process of coating the AgCl shell on the surface of the metal nanowire is as follows: adding PVP solution as a dispersing agent, stirring for 5min, and dropwise adding 5.0-10.0 mmol/L AgNO₃Stirring the solution for 60min, and dropwise adding 5.0-10.0 mmol/L FeCl₃Stirring the solution for 60min, ultrasonically cleaning the solution by using deionized water, and centrifuging the solution to obtain a precipitate to obtain the composite nano catalyst.

10. The application of the high-efficiency visible light driven composite nano catalyst in the field of trivalent arsenic preoxidation;

the application of the high-efficiency visible light driven composite nano catalyst in the field of degrading organic matters;

an application of a high-efficiency visible light driven composite nano catalyst in the field of sterilization treatment.

Technical Field

The invention relates to the technical field of nano material preparation. More specifically, the invention relates to a high-efficiency visible light driven composite nano catalyst, a preparation method and application thereof.

Background

In recent years, photocatalysis is a green technology which is a research hotspot in the field of energy and environment nowadays. The Ag/AgX (X ═ halogen element, Cl, Br, I) photocatalyst has good visible light absorption due to noble metal plasma resonance effect, and overcomes the defect of TiO₂In view of the problem of low solar light utilization efficiency, the photocatalyst exhibits high photocatalytic activity for organic substances, and has become a new subject of research on visible light catalytic materials in recent years. However, Ag/AgX has the problems of high price, difficult separation from water and the like. Researchers turned their eyes to the development of magnetic silver-based photocatalytic materials that respond to visible light. The magnetic material is compounded with the silver-based photocatalyst with high-efficiency photocatalytic activity, so that the catalytic activity of the catalyst under visible light and the stability of the material are improved, the consumption of noble metal is reduced, the cost is saved, the photocatalyst can be quickly separated and recovered from a reaction solution, and the research of the photocatalytic technology is made to make a breakthrough progress. The current research is mainly focused on a few iron oxide magnetic materials, such as Fe₃O₄、Fe₂O₃、MFe₂O₄Iron oxide nanoparticles (such as (M ═ Zn, Ni, Co, Cu)) as core and coating activityAnd further obtaining the magnetic nano-particles with the core-shell structure by using the substances. The synthesis method is single, only the nano material in the shape of particles can be synthesized, and the iron oxide nano particles are easy to self-agglomerate and are not beneficial to the photocatalysis performance of the material. There is no research report on the composition of the magnetic zero-valent iron and the silver-based optical driving material at home and abroad.

Disclosure of Invention

An object of the present invention is to solve at least the above problems and to provide at least the advantages described later.

The invention also aims to provide a high-efficiency visible light driven composite nano catalyst, a preparation method of the high-efficiency visible light driven composite nano catalyst and application of the high-efficiency visible light driven composite nano catalyst, and magnetic photocatalytic nano materials are synthesized by virtue of paramagnetism of zero-valent iron. The defect that the iron oxide magnetic nano material is easy to self-agglomerate is overcome, and the magnetic photocatalytic nano material can be quickly separated, recycled and reused through an external magnetic field. The method can effectively reduce the treatment cost and material loss, realize long-term cyclic utilization of the visible light driving material and reduce secondary pollution.

To achieve these objects and other advantages in accordance with the present invention, there is provided a high efficiency visible light driven composite nanocatalyst including a metal nanowire core and an AgX shell coated on the metal nanowire core, wherein the metal nanowire core is one of Fe-Ag segmented nanowires and Fe nanowires, and X is one of Cl, Br, and I.

The preparation method comprises the steps of preparing the metal nanowire by adopting a template method through pulse electrodeposition, removing the template, and coating an AgCl shell on the surface of the metal nanowire to obtain the composite nano catalyst.

Preferably, the electrodeposition solution used in the electrodeposition is one or both of an Ag electrodeposition electrolyte containing thiourea and an Fe electrodeposition electrolyte containing sodium citrate.

Preferably, the concentration of thiourea and the concentration of silver-containing substances in the Ag electrodeposition electrolyte are respectively 0.0-0.45 mol/L and 2.0-7.0 mmol/L; the concentration of sodium citrate in the Fe electrodeposition electrolyte is 0.1-0.5 mol/L, and the concentration of ferrous sulfate is 0.2-0.5 mol/L.

Preferably, the electrodeposition is completed by adopting a three-electrode system connected with an electrochemical workstation, a PC template is taken as a working electrode, a platinum mesh electrode is taken as a counter electrode, a saturated calomel electrode is taken as a reference electrode, and the electrolytic cell is composed of polytetrafluoroethylene capable of fixing and replacing a PC membrane.

Preferably, after addition of the Ag electrodeposition electrolyte, the electrodeposition pulse cycle parameters are applied: t is t_off＝0～20s，I＝-2～0mA，t_onThe deposition time is 10-40 s and 0-90 min.

Preferably, after the addition of the Fe electrodeposition electrolyte, the electrodeposition pulse cycle parameters are applied: t is t_off＝0～20s，I＝-4.5～0mA，t_onThe deposition time is 0-40 s and 0-30 min.

Preferably, after the electrodeposition is finished, taking out the PC membrane on the PC template, repeatedly washing with deionized water, dissolving with dichloromethane, carrying out ultrasonic treatment for 10-30 s, and then standing for 2-12 h to obtain the independently dispersed metal nanowires.

Preferably, the specific process of coating the AgCl shell on the surface of the metal nanowire comprises the following steps: adding PVP solution as a dispersing agent, stirring for 5min, and dropwise adding 5.0-10.0 mmol/L AgNO₃Stirring the solution for 60min, and dropwise adding 5.0-10.0 mmol/L FeCl₃Stirring the solution for 60min, ultrasonically cleaning the solution by using deionized water, and centrifuging the solution to obtain a precipitate to obtain the composite nano catalyst.

The application of the high-efficiency visible light driven composite nano catalyst in the field of trivalent arsenic preoxidation;

the application of the high-efficiency visible light driven composite nano catalyst in the field of degrading organic matters;

an application of a high-efficiency visible light driven composite nano catalyst in the field of sterilization treatment.

The invention at least comprises the following beneficial effects:

the preparation method is simple, the preparation cost of the photocatalytic material with the plasma effect is greatly reduced, the obtained material is uniform in size, strong in paramagnetism and high in photocatalytic oxidation performance, magnetic recovery is easy to realize, and the service life and the reproducibility are excellent;

compared with common noble metal semiconductor materials, the introduction of the zero-valent iron not only reduces the material cost and is beneficial to industrial application, but also endows the material with magnetism, so that the material can be quickly and simply recovered by applying a magnetic field;

the magnetic particles selected in the invention are zero-valent iron, and compared with the iron oxide serving as the magnetic particles in the prior art, the zero-valent iron is less prone to agglomeration and has better dispersibility in the solution, so that the catalytic efficiency in practical application is improved;

the one-dimensional linear material is obtained by adopting the template method through electrodeposition, and compared with the granular magnetic material widely adopted at present, the one-dimensional structure is more beneficial to improving the material performance.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a scanning electron microscope image of a segmented Fe-Ag nanowire according to example 1 of the present invention;

FIG. 2 is a scanning electron micrograph of Fe-Ag @ AgCl nanowires of example 1 of the present invention;

FIG. 3 is a scanning electron microscope image of Fe @ AgCl nanowires of example 2 of the invention.

Detailed Description

The present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.

It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified.

< example 1>

Step one, preparing an electrodeposition electrolyte.

During electrochemical deposition, the selection of the complexing agent is most important. The addition of the complexing agent can promote the slow progress of the whole electrodeposition processThereby obtaining an effective, dense nanowire material. On the basis of multiple attempts, thiourea is respectively adopted and selected as Ag by comparing the action effects of different complexing agents⁺Ag electrodeposition electrolyte of complexing agent and Fe selected from sodium citrate²⁺Fe of complexing agent electrodeposits electrolyte.

Ag electrodeposition electrolyte: weighing 17.127g of thiourea, adding deionized water, stirring until the thiourea is completely dissolved, weighing 1.091g of silver sulfate white solid, adding the silver sulfate white solid into the solution, stirring at room temperature until the solid is completely dissolved, placing the solution into a 500ml volumetric flask, adding deionized water, and titrating to a scale mark;

fe electrodeposition electrolyte: 73.525g of sodium citrate is weighed and added into deionized water, after stirring until the sodium citrate is completely dissolved, 69.508g of ferrous sulfate solid is weighed and added into the solution, the solution is stirred at room temperature until the solid is completely dissolved, the solution is black green, the solution is transferred into a 500ml volumetric flask, and the deionized water is added to dilute and titrate the solution to a scale mark.

And step two, preparing the Fe-Ag segmented nanowire by using a template method through pulse electrodeposition.

A traditional three-electrode system is adopted, an electrolytic cell is composed of polytetrafluoroethylene capable of fixing and replacing a PC membrane, and the volume of the electrolytic cell is 100 mL. The PC film was fixed on a metal plate as a working electrode (working area: 2.54 cm)²) Platinum mesh electrode (20 mm. times.20 mm) as counter electrode and Saturated Calomel Electrode (SCE) as reference electrode. The three-electrode system is connected with an electrochemical workstation to control the pulse electrodeposition.

The pulsed electrodeposition process consists of two parts. Step one, 100ml of Ag electrodeposition electrolyte is added into the electrolytic cell, a counter electrode and a reference electrode are respectively inserted, and electrodeposition pulse period parameters are applied: t is t_off＝20s，I＝-2mA，t_onDeposition time was 90min for 20 s. And secondly, replacing the Ag electrodeposition solution in the electrolytic cell with 100ml Fe electrodeposition solution, and applying electrodeposition pulse period parameters: t is t_off＝20s，I＝-4.5mA，t_onDeposition time 30min, 30 s. The platinum mesh of the counter electrode should be kept parallel to the PC membrane during the process. And applying a magnetic stirrer to the solutionStirring is carried out to reduce concentration polarization in the electrodeposition process and ensure the uniform deposition of the metal nanowires. And after the electrodeposition is finished, taking out the PC membrane, and repeatedly washing the PC membrane by using deionized water to remove the redundant solution on the surface. And then, dissolving the diaphragm by using dichloromethane, carrying out ultrasonic treatment for 30s, and standing the diaphragm dissolved solution for 12h to obtain the Fe-Ag segmented nanowire which is independent in dispersion. Then, the Fe-Ag segmented nanowires are repeatedly subjected to ultrasonic cleaning and centrifugation for 3 times by using an ethanol solution, so that residual PC films are removed, and a small amount of ethanol is used for storing the Fe-Ag segmented nanowires.

And step three, chlorination of the nanowires.

Ultrasonically cleaning Fe-Ag nanowire with deionized water, centrifuging for 3 times, dispersing in 2.5ml of deionized water, adding 100 mu l of PVP solution as a dispersing agent, electrically stirring for 5min, and dropwise adding 2ml of 8mmol/LAgNO₃The solution is stirred for 60min electrically, and then 2.5ml of 7mmol/L FeCl which is newly prepared is added dropwise₃And (3) electrically stirring the solution for 60min, ultrasonically cleaning the solution by using deionized water, and centrifuging the solution for 3 times to finally obtain the one-dimensional magnetic Fe-Ag @ AgCl nanowire.

< example 2>

Step one, the preparation of the electrodeposition electrolyte, the preparation method of which is the same as example 1, except that the concentration of thiourea in the Ag electrodeposition electrolyte is 0.1mol/L, the concentration of the silver-containing substance is 2.0mmol/L, the concentration of sodium citrate in the Fe electrodeposition electrolyte is 0.1mol/L, and the concentration of ferrous sulfate is 0.2 mol/L.

And step two, preparing the Fe-Ag segmented nanowire by using a template method through pulse electrodeposition.

The three-electrode system of example 1 was used.

The pulsed electrodeposition process consists of two parts. Step one, 100ml of Ag electrodeposition electrolyte is added into the electrolytic cell, a counter electrode and a reference electrode are respectively inserted, and electrodeposition pulse period parameters are applied: t is t_off＝0s，I＝0mA，t_onDeposition time was 15min, 10 s. And secondly, replacing the Ag electrodeposition solution in the electrolytic cell with 100ml Fe electrodeposition solution, and applying electrodeposition pulse period parameters: t is t_off＝0s，I＝0mA，t_onDeposition time 10min, 10 s. Should be kept in alignment during the processThe platinum mesh of the electrode should be parallel to the PC membrane. And a magnetic stirrer is used for stirring the solution so as to reduce concentration polarization in the electrodeposition process and ensure the uniform deposition of the metal nanowires. And after the electrodeposition is finished, taking out the PC membrane, and repeatedly washing the PC membrane by using deionized water to remove the redundant solution on the surface. And then, dissolving the diaphragm by using dichloromethane, carrying out ultrasonic treatment for 10s, and standing the diaphragm dissolved solution for 2h to obtain the Fe-Ag segmented nanowire which is independent in dispersion. Then, the Fe-Ag segmented nanowires are repeatedly subjected to ultrasonic cleaning and centrifugation for 3 times by using an ethanol solution, so that residual PC films are removed, and a small amount of ethanol is used for storing the Fe-Ag segmented nanowires.

And step three, chlorination of the nanowires.

Ultrasonically cleaning Fe-Ag nanowire with deionized water, centrifuging for 3 times, dispersing in 2.5ml of deionized water, adding 100 mu l of PVP solution as a dispersing agent, electrically stirring for 5min, and dropwise adding 2ml of 5mmol/LAgNO₃The solution is stirred for 60min electrically, and then 2.5ml of 5mmol/L FeCl which is newly prepared is added dropwise₃And (3) electrically stirring the solution for 60min, ultrasonically cleaning the solution by using deionized water, and centrifuging the solution for 3 times to finally obtain the one-dimensional magnetic Fe-Ag @ AgCl nanowire.

< example 3>

Step one, the preparation of the electrodeposition electrolyte, the preparation method of which is the same as example 1, except that the concentration of thiourea in the Ag electrodeposition electrolyte is 0.15mol/L, the concentration of the silver-containing substance is 5mmol/L, the concentration of sodium citrate in the Fe electrodeposition electrolyte is 0.3mol/L, and the concentration of ferrous sulfate is 0.3 mol/L.

And step two, preparing the Fe-Ag segmented nanowire by using a template method through pulse electrodeposition.

The three-electrode system of example 1 was used.

The pulsed electrodeposition process consists of two parts. Step one, 100ml of Ag electrodeposition electrolyte is added into the electrolytic cell, a counter electrode and a reference electrode are respectively inserted, and electrodeposition pulse period parameters are applied: t is t_off＝10s，I＝-1mA，t_onDeposition time was 45min for 40 s. And secondly, replacing the Ag electrodeposition solution in the electrolytic cell with 100ml Fe electrodeposition solution, and applying electrodeposition pulse period parameters: t is t_off＝10s，I＝-2.5mA，t_onDeposition time 15min, 40 s. The platinum mesh of the counter electrode should be kept parallel to the PC membrane during the process. And a magnetic stirrer is used for stirring the solution so as to reduce concentration polarization in the electrodeposition process and ensure the uniform deposition of the metal nanowires. And after the electrodeposition is finished, taking out the PC membrane, and repeatedly washing the PC membrane by using deionized water to remove the redundant solution on the surface. And then, dissolving the diaphragm by using dichloromethane, carrying out ultrasonic treatment for 30s, and standing the diaphragm dissolved solution for 12h to obtain the Fe-Ag segmented nanowire which is independent in dispersion. Then, the Fe-Ag segmented nanowires are repeatedly subjected to ultrasonic cleaning and centrifugation for 3 times by using an ethanol solution, so that residual PC films are removed, and a small amount of ethanol is used for storing the Fe-Ag segmented nanowires.

And step three, chlorination of the nanowires.

Ultrasonically cleaning Fe-Ag nanowire with deionized water, centrifuging for 3 times, dispersing in 2.5ml of deionized water, adding 100 mu l of PVP solution as a dispersing agent, electrically stirring for 5min, and dropwise adding 2ml of 10mmol/LAgNO₃The solution is stirred for 60min electrically, and then 2.5ml of 10mmol/L FeCl which is newly prepared is added dropwise₃And (3) electrically stirring the solution for 60min, ultrasonically cleaning the solution by using deionized water, and centrifuging the solution for 3 times to finally obtain the one-dimensional magnetic Fe-Ag @ AgCl nanowire.

< example 4>

The preparation steps of the one-dimensional magnetic iron-based photocatalytic nanomaterial Fe @ AgCl nanowire are the same as those of example 1, wherein the difference is that only Fe electrodeposition electrolyte is adopted for pulse electrodeposition in the step two.

< example 5>

The one-dimensional magnetic Fe-Ag @ AgCl nanowire is added into dye wastewater, organic wastewater and a liquid environment containing trivalent arsenic respectively, under the action of visible light, a large amount of active oxygen free radicals can be rapidly generated, and the active oxygen free radicals can be made to contain 10⁷The CFU/mL of the escherichia coli solution is reduced to be within the range of 0-10CFU/mL within 60 minn; the effective removal rate of 2.0mg/L methylene blue solution in 60minn reaches more than 92 percent; 10.0mg/L of As (III) achieves effective removal within 120 minn.

The one-dimensional magnetic Fe @ AgCl nanowires are respectively added into dye wastewater, organic wastewater and a liquid environment containing trivalent arsenic, so that the dye wastewater and the organic wastewater can be subjected to oxidation treatment, and the trivalent arsenic can be subjected to pre-oxidation treatment and water sterilization and disinfection treatment.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable to various fields of endeavor for which the invention may be embodied with additional modifications as would be readily apparent to those skilled in the art, and the invention is therefore not limited to the details given herein and to the embodiments shown and described without departing from the generic concept as defined by the claims and their equivalents.