CN102583566A - Preparation method for bismuth ferrate nano fibers - Google Patents

Abstract

The invention discloses a preparation method for bismuth ferrate nano fibers and aims to solve the technical problem that the traditional photocatalytic material has a wide band gap. The invention adopts the technical scheme which comprises the following steps of: dissolving citric acid in deionized water to form a citric acid solution; adding ferric nitrate and bismuth nitrate into the citric acid solution, stirring the mixture until the mixture is clear and transparent, after standing the solution, heating and stirring the solution in a water-bath pot, adding polyvinylpyrrolidone into the solution, continuously stirring until the polyvinylpyrrolidone is completely dissolved, keeping the concentration of the polyvinylpyrrolidone, performing electrostatic spinning by using an injection pump and a high-pressure power supply, and collecting the fibers by using a monocrystalline wafer; and after drying the collected fibers in a drying box, calcining the fibers at consistent temperature in a muffle furnace to obtain the bismuth ferrate nano fibers. The band gap of the bismuth ferrate nano fibers prepared by the preparation method is reduced from 3.2 to 3.4ev in the background technology to below 2.1ev.

Description

Preparation method of bismuth ferrite nanofiber

technical field

The invention relates to a method for preparing nanofibers, in particular to a method for preparing bismuth ferrite nanofibers.

Background technique

Photocatalytic materials are chemical substances that can play a catalytic role under the excitation of photons, and are extremely important functional materials. Photocatalytic technology is a bionic technology, which is widely used in many cutting-edge fields such as energy conservation and environmental protection, new energy, and biomedicine.

Document "A.K.Alves, F.A.Berutti, F.J.Clemensb, T.Grauleb and C.P.Bergmann, Photocatalytic activity of titania fibers obtained by electrospinning, Materials Research Bulletin, 2009, 44, 312-317" discloses a method for preparing titanium dioxide photocatalytic material, This method adopts the electrospinning method to prepare titanium dioxide photocatalytic material, but the bandgap width of this titanium dioxide photocatalytic material is 3.2-3.4ev, because of the wide bandgap, it cannot absorb visible light very well, and cannot satisfy the high efficiency of sunlight. absorbing requirements.

Contents of the invention

In order to overcome the shortage of existing photocatalytic materials with wide band gaps, the invention provides a method for preparing bismuth ferrite nanofibers. In this method, citric acid is dissolved in deionized water to form a citric acid solution; then ferric nitrate and bismuth nitrate are added to the citric acid solution and stirred until clear and transparent; Polyvinylpyrrolidone, continue to stir until the polyvinylpyrrolidone is completely dissolved, maintain the concentration of polyvinylpyrrolidone, use a syringe pump and a high-voltage power supply to perform electrospinning, and collect the fibers with a single crystal silicon wafer; place the collected fibers in a drying box to dry Then put it into a muffle furnace for heat preservation and calcining to obtain bismuth ferrite nanofibers. This preparation method can reduce the band gap width of the prepared bismuth ferrite nanofibers.

The technical scheme adopted by the present invention to solve its technical problems: a kind of preparation method of bismuth ferrite nanofiber, it is characterized in that comprising the following steps:

(a) dissolving citric acid into deionized water to form a concentration of 0.2 to 0.4 g/mL citric acid solution;

(b) adding ferric nitrate and bismuth nitrate to the citric acid solution and stirring until clear and transparent, wherein the molar ratio of ferric nitrate, bismuth nitrate and citric acid is 2:1:6;

(c) After the solution prepared in step (b) is left to stand for 24 to 72 hours, it is placed in a water bath and heated and stirred at 50 to 90° C. for 3 to 7 hours, and polyethylene with a molecular weight of 1.3×10 ⁶ is added to the solution. Pyrrolidone, continue to stir until the polyvinylpyrrolidone is completely dissolved, so that the concentration of polyvinylpyrrolidone is kept at 0.02-0.05g/mL;

(d) Add the polymer solution prepared in step (c) to a plastic syringe with an inner diameter of 1-3mm and a stainless steel needle, add the syringe to the syringe pump, and start the syringe pump to make the injection flow rate 0.3-0.7mL /h, at the same time, turn on the high-voltage power supply to provide a voltage of 20-30kV to the needle, and collect the fiber with a single crystal silicon wafer;

(e) Place the collected fibers in a drying oven and dry them at 100-150°C for 4-8 hours, then put them in a muffle furnace to raise the temperature to 600-800°C at a heating rate of 1-5°C/min, and keep them warm Calcining for 4-8 hours to obtain bismuth ferrite nanofibers.

The beneficial effect of the present invention is: because this method dissolves citric acid into deionized water to form a citric acid solution; then add ferric nitrate and bismuth nitrate to the citric acid solution and stir until it is clear and transparent, and then place the solution in a water bath Heat and stir in medium, add polyvinylpyrrolidone to the solution, continue to stir until the polyvinylpyrrolidone is completely dissolved, maintain the concentration of polyvinylpyrrolidone, use a syringe pump and a high-voltage power supply to carry out electrospinning, and collect fibers with a single crystal silicon chip; the collected The fibers are placed in a drying oven and dried and then put into a muffle furnace for heat preservation and calcination to obtain bismuth ferrite nanofibers. The band gap width of bismuth ferrite nanofibers prepared by this preparation method is reduced from 3.2 to 3.4ev in the background technology to 2.0～2.1ev.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is the scanning electron microscope spectrum of bismuth ferrite nanofibers prepared in Example 2 of the method of the present invention.

Fig. 2 is a curve of the degradation rate of bismuth ferrite nanofibers prepared in Example 2 of the method of the present invention to methyl orange solution under visible light.

Detailed ways

Example 1, first dissolving citric acid into deionized water to form a citric acid solution with a concentration of 0.2g/mL; then adding iron nitrate and bismuth nitrate to the citric acid solution and stirring until clear and transparent, wherein The molar ratio of the acid is 2: 1: 6; after the solution is allowed to stand for 48 hours, it is placed in a water bath and heated and stirred at 60° C. for 4 hours, and the polyvinylpyrrolidone with a molecular weight of 1.3×10 ⁶ is added to the solution, and the stirring is continued until The polyvinylpyrrolidone is completely dissolved, so that the concentration of polyvinylpyrrolidone is kept at 0.03g/mL; finally, this polymer solution is added to a plastic syringe with an inner diameter of 2 mm and a stainless steel needle, and the syringe is added to the syringe pump, and the The syringe pump makes the injection flow rate 0.3mL/h, and at the same time, turn on the high-voltage power supply to provide a voltage of 20kV to the needle, and collect the fibers with a single crystal silicon wafer; place the collected fibers in a drying oven at 100°C for 8 hours and then put them in a horse. The temperature was raised to 650° C. in a Furnace at a heating rate of 3° C./min, and kept for calcination for 5 hours to obtain bismuth ferrite nanofibers.

After testing, the bandgap width of the bismuth ferrite nanofibers prepared in this example is 2.1 eV.

Example 2, first dissolving citric acid into deionized water to form a citric acid solution with a concentration of 0.4g/mL; then adding ferric nitrate and bismuth nitrate to the citric acid solution and stirring until clear and transparent, wherein ferric nitrate, bismuth nitrate, lemon The molar ratio of the acid is 2: 1: 6; after the solution is allowed to stand for 24 hours, it is placed in a water bath and heated and stirred at 50° C. for 7 hours, and the polyvinylpyrrolidone with a molecular weight of 1.3×10 ⁶ is added to the solution, and the stirring is continued until The polyvinylpyrrolidone is completely dissolved, so that the concentration of polyvinylpyrrolidone is kept at 0.02g/mL; finally, this high polymer solution is added to a plastic syringe with an inner diameter of 1 mm and a stainless steel needle, and the syringe is added to the syringe pump, and the injection pump is started. The syringe pump makes the injection flow rate 0.7mL/h, and at the same time, turn on the high-voltage power supply to provide a voltage of 25kV to the needle, and collect the fibers with a single crystal silicon wafer; place the collected fibers in a drying oven at 130°C for 5 hours and then put them in a horse. The temperature was raised to 750° C. in a Furnace at a heating rate of 1° C./min, and kept for calcination for 4 hours to obtain bismuth ferrite nanofibers.

After testing, the bandgap width of the bismuth ferrite nanofibers prepared in this example is 2.1 eV. It can be seen from the scanning electron microscope spectrum in Fig. 1 that the prepared fiber has a good shape and a diameter of about 2 microns. It can be seen from Figure 2 that the prepared bismuth ferrite nanofibers have more excellent photocatalytic effect than the methyl orange solution without catalyst.

Example 3, first dissolving citric acid into deionized water to form a citric acid solution with a concentration of 0.3g/mL; then adding ferric nitrate and bismuth nitrate to the citric acid solution and stirring until clear and transparent, wherein ferric nitrate, bismuth nitrate, lemon The molar ratio of the acid is 2: 1: 6; after the solution is allowed to stand for 72 hours, it is placed in a water bath and heated and stirred at 70° C. for 6 hours, and the solution is added with polyvinylpyrrolidone with a molecular weight of 1.3×10 ⁶ and continued to stir until The polyvinylpyrrolidone is completely dissolved, so that the concentration of polyvinylpyrrolidone is kept at 0.04g/mL; finally, this polymer solution is added to a plastic syringe with an inner diameter of 3 mm and a stainless steel needle, and the syringe is added to the syringe pump, and the The syringe pump makes the injection flow rate 0.4mL/h, and at the same time, turn on the high-voltage power supply to provide a voltage of 30kV to the needle, and collect the fibers with a single crystal silicon wafer; place the collected fibers in a drying oven at 150°C for 4 hours and then put them in a horse. The temperature was raised to 800° C. in a Furnace at a heating rate of 5° C./min, and kept for calcination for 4 hours to obtain bismuth ferrite nanofibers.

After testing, the bandgap width of the bismuth ferrite nanofibers prepared in this example is 2.05 eV.

Example 4, first dissolving citric acid into deionized water to form a citric acid solution with a concentration of 0.3g/mL; then adding ferric nitrate and bismuth nitrate to the citric acid solution and stirring until clear and transparent, wherein ferric nitrate, bismuth nitrate, lemon The molar ratio of the acid is 2: 1: 6; after the solution is allowed to stand for 36 hours, it is placed in a water bath and heated and stirred at 90° C. for 3 hours, and the solution is added with polyvinylpyrrolidone with a molecular weight of 1.3×10 ⁶ and continued to stir until The polyvinylpyrrolidone is completely dissolved, so that the concentration of polyvinylpyrrolidone is kept at 0.05g/mL; finally, this polymer solution is added to a plastic syringe with an inner diameter of 2mm and a stainless steel needle, and the syringe is added to the syringe pump, and the The syringe pump makes the injection flow rate 0.6mL/h, and at the same time, turn on the high-voltage power supply to provide a voltage of 25kV to the needle, and collect the fibers with a single crystal silicon wafer; place the collected fibers in a drying oven at 140°C for 6 hours and then put them in a horse. The temperature was raised to 600° C. in a Furnace at a heating rate of 4° C./min, and kept for calcination for 8 hours to obtain bismuth ferrite nanofibers.

After testing, the bandgap width of the bismuth ferrite nanofibers prepared in this example is 2.0 eV.

The present invention also makes preparations for the parameter ranges given in the technical solution, all of which have achieved good results.

The bismuth ferrite nanofiber prepared by the method of the invention has good microscopic appearance, and has good degradation effect on methyl orange solution under visible light irradiation. At the same time, the preparation process of the bismuth ferrite nanofiber is simple and easy, so the method for preparing the bismuth ferrite fiber of the present invention is suitable for industrial promotion and large-scale production, and has broad application prospects in new photocatalytic materials.

Claims (1)

1. a bismuth ferrate nano fiber preparation method is characterized in that comprising the steps:

(a) Hydrocerol A is dissolved in the deionized water to form concentration be 0.2～0.4g/mL citric acid solution;

(b) with iron nitrate, Bismuth trinitrate add to stir to clarify in the citric acid solution transparent, the mol ratio 2: 1: 6 of iron nitrate, Bismuth trinitrate, Hydrocerol A wherein;

(c) solution left standstill of step (b) preparation is placed 24～72 hours after, be placed in the water-bath in 50～90 ℃ of heated and stirred 3～7 hours, in solution, adding molecular weight is 1.3 * 10 ⁶Vinylpyrrolidone polymer, continue to be stirred to Vinylpyrrolidone polymer and dissolve fully, make the concentration of Vinylpyrrolidone polymer remain on 0.02～0.05g/mL;

(d) it is 1～3mm that the high polymeric solution that step (c) is prepared adds internal diameter to; Syringe needle is in the plastic injector of stainless steel syringe needle; Syringe is added in the syringe pump; Starting syringe pump, to make the injection flow velocity be 0.3～0.7mL/h, opens high-voltage power supply simultaneously and to syringe needle the voltage of 20～30kV is provided, and collects fiber with monocrystalline silicon piece;

(e) place loft drier to put into retort furnace after 4～8 hours the fiber of collecting and be warming up to 600～800 ℃, and, obtain the bismuth ferrate nano fiber in insulation calcining 4～8 hours with the heat-up rate of 1～5 ℃/min 100～150 ℃ of dryings.

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