A method for regulating the spacing of orderly arranged nanowires

Abstract

The present invention provides a method for regulating the spacing of orderly arranged nanowires, comprising the following steps: preparing silver nanowires of uniform size, washing, adjusting the pH value after dispersion, adding dopamine, reacting, washing the obtained reaction product, ultrasonically dispersing it in a solvent, assembling an orderly nanowire film using a Langmuir-Blodgett assembly method, and then soaking it in a potassium hydroxide solution and taking it out. The method can regulate the spacing between nanomaterials at a microscopic scale and can be prepared on a large scale.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material assembly, and in particular relates to a method for regulating the spacing of orderly arranged nano wires. Background Art

[0002] In recent years, as the requirements for computer chip processing accuracy continue to increase, photolithography technology has received more and more attention. High-precision photolithography is to etch materials at the nanoscale to obtain the desired nanostructure. However, photolithography equipment is expensive and key technologies are blocked by foreign companies. By using Langmuir-Blodgett assembly technology, nanomaterials at the microscale can be micro-regulated at the macro level, so that nanomaterials are arranged in order between the two phase interfaces, and then the arranged nanomaterials can be transferred to different substrates according to needs.

[0003] For example, the document "Journal of the American Chemical Society" (J.Am.Chem.Soc. 2017, Vol. 139, p. 9221) reported that the Langmuir-Blodgett assembly technique was used to orderly assemble silver nanowires and tungsten oxide nanowires to obtain an orderly arranged nanowire film. In addition, the orderly arrangement of nanowires will bring about certain performance improvements. For example, the document "Journal of the American Chemical Society" (J.Am.Chem.Soc. 2019, Vol. 141, p. 10729) reported that the Langmuir-Blodgett assembly technique was used to orderly assemble platinum nanotubes. Under the same conditions, the assembled orderly arranged platinum nanotubes have significantly improved performance in electrocatalytic methanol oxidation compared to disordered platinum nanotubes. The prior art generally uses microfluidics or photolithography technology to design and adjust nanostructures to prepare nanomaterial films with adjustable spacing, but these methods have long processes and high costs, and cannot prepare nanomaterial films with controllable spacing on a large scale and efficiently. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a method for regulating the spacing between orderly arranged nanowires, which method can regulate the spacing between nanomaterials at a microscopic scale and can be prepared on a large scale.

[0005] The present invention provides a method for regulating the spacing of orderly arranged nanowires, comprising the following steps:

[0006] Silver nanowires of uniform size are prepared, washed, and the pH value is adjusted after dispersion, and then dopamine is added to react. The reaction product is washed, ultrasonically dispersed in a solvent, and an ordered nanowire film is assembled using the Langmuir-Blodgett assembly method, and then immersed in a potassium hydroxide solution and taken out.

[0007] In the present invention, the preparation of silver nanowires with uniform size preferably comprises the following steps:

[0008] Mix polyvinyl pyrrolidone and glycerol, heat to 98-103° C., cool, add silver nitrate, then add sodium chloride solution, heat to 200-220° C., stop heating, add deionized water, cool, and obtain silver nanowires.

[0009] In the present invention, the reaction time is 5.5 to 6.5 hours. In a specific embodiment, the reaction time is 6 hours.

[0010] In the present invention, the solvent includes N,N-dimethylformamide and chloroform. In the present invention, after the reaction product is washed, N,N-dimethylformamide is added first, and then chloroform is added.

[0011] In the present invention, the mass ratio of the silver nanowires to dopamine is 14:1 to 10. In a specific embodiment, the amount of each group of silver nanowires is 0.14 g; the mass ratio of the silver nanowires to dopamine is 14:1; or 14:2; or 14:4; or 14:6; or 14:8; or 14:10.

[0012] The pH value is adjusted by using tris(hydroxymethyl)aminomethane; the mass ratio of tris(hydroxymethyl)aminomethane to dopamine is 2:(1-10). In a specific embodiment, the mass ratio of tris(hydroxymethyl)aminomethane to dopamine is 2:1; or 1:2; or 2:4; or 2:6; or 2:8; or 2:10.

[0013] In the present invention, the concentration of the potassium hydroxide solution is 0.9-1.1 mol / L. The potassium hydroxide solution etches away the polydopamine on the surface of the silver nanowires to expose the silver nanowires. In a specific embodiment, the concentration of the potassium hydroxide solution is 1 mol / L.

[0014] In the present invention, the soaking time is 2.5 to 3.5 minutes.

[0015] In the present invention, the spacing between nanowires in the ordered nanowire film is 8 to 50 nm. In a specific embodiment, the spacing between nanowires in the ordered nanowire film is 8 nm, 15 nm, 24 nm, 35 nm, 42 nm and 50 nm.

[0016] The present invention provides a method for regulating the spacing of orderly arranged nanowires, comprising the following steps: preparing silver nanowires of uniform size, washing, adjusting the pH value after dispersion, adding dopamine, reacting, washing the obtained reaction product, ultrasonically dispersing it in a solvent, assembling an orderly nanowire film using a Langmuir-Blodgett assembly method, and then soaking it in a potassium hydroxide solution and taking it out. The method can regulate the spacing between nanomaterials at a microscopic scale and can be prepared on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the XRD spectrum of silver nanowires in an embodiment of the present invention;

[0018] Figure 2 A transmission electron microscope image of silver nanowires in an embodiment of the present invention;

[0019] Figure 3 This is a transmission image of dopamine coated on the silver nanoparticle surface (bottle No. 6);

[0020] Figure 4 Transmission electron microscopy images of ordered silver nanowires with uniform spacing were obtained to control the polydopamine wrapping with different thicknesses;

[0021] Figure 5 A photo schematic of the transfer of coated silver nanowires onto carbon paper after assembly using the Langmuir-Blodgett technique;

[0022] Figure 6 Faradaic efficiency test curves for the electrocatalytic reduction of carbon monoxide by carbon dioxide with ordered silver nanowires of different spacings. DETAILED DESCRIPTION

[0023] In order to further illustrate the present invention, a method for regulating the spacing between orderly arranged nanowires provided by the present invention is described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0024] Example 1

[0025] 1. Synthesis of silver nanowires

[0026] Weigh 2.93 g of polyvinyl pyrrolidone (molecular weight approximately equal to 30,000) and add it to a 250 ml three-necked flask, then add 95 ml of propylene glycol, stir and heat to 100°C to completely dissolve the polyvinyl pyrrolidone, then cool to room temperature. Add 0.79 g of silver nitrate to the flask, then weigh 29.5 mg of sodium chloride and dissolve it in 0.25 ml of deionized water and 5 ml of glycerol, then add it to the flask. Heat and stir the solution to 210°C, then stop heating, add 100 ml of deionized water, cool and centrifuge to obtain silver nanowires.

[0027] 2. Polydopamine coated silver nanowires

[0028] Take 6 portions of 10 ml silver nanowires, wash them twice with deionized water by centrifugation, and then disperse them in 20 ml deionized water. Then add the 6 portions of silver nanowires to 6 conical flasks and number the conical flasks in sequence. Then add 0.5 ml of tris(hydroxymethylaminomethane) solution (20 mg dissolved in 0.5 ml deionized water) to each conical flask, and then add different amounts of dopamine according to the number of the conical flasks. Add 10 mg of dopamine to bottle No. 1, 20 mg of dopamine to bottle No. 2, 40 mg of dopamine to bottle No. 3, 60 mg of dopamine to bottle No. 4, 80 mg of dopamine to bottle No. 5, and 100 mg of dopamine to bottle No. 6. All dopamine is first dissolved in 0.5 ml of deionized water and then added to the conical flask. Shake evenly and then react at room temperature for 6 hours.

[0029] 3. Assembly and etching

[0030] After the above reaction is completed, take 5 ml of the nanowire solution in the conical flask No. 1 and wash it with deionized water by centrifugation, then add 1 ml of N,N-dimethylformamide, and then shake and ultrasonicate to disperse the nanowires in N,N-dimethylformamide, and then add 1 ml of chloroform and shake evenly. Then inject deionized water into the LB instrument, and then drop the dispersed nanowires onto the water surface, squeeze the nanowires until wrinkles appear on both sides of the nanowire film on the liquid surface, let it stand for 10 minutes, and then transfer the nanowire film to the transmission copper mesh and carbon paper respectively. Then immerse the transmission copper mesh and carbon paper in 1 mol per liter potassium hydroxide solution for 3 minutes, and then take it out. Then repeat the same operation to prepare the nanowires in the remaining conical flasks into nanowire films, and the obtained films are recorded as: nanowire film-1, nanowire film-2, nanowire film-3, nanowire film-4, nanowire film-5 and nanowire film-6.

[0031] The present invention tests the performance of the prepared nanowire film, and the results are shown in Figure 6 ,Depend on Figure 6It can be seen that silver nanowires with different spacings can be used as reducing agents for the electrocatalytic reduction of carbon dioxide. The ratio of carbon monoxide in the obtained catalytic reduction product to the total catalytic reduction product (i.e., the Faraday efficiency) is affected by the spacing of the nanowires.

[0032] As can be seen from the above embodiments, the present invention provides a method for regulating the spacing of orderly arranged nanowires, comprising the following steps: preparing silver nanowires of uniform size, washing, adjusting the pH value after dispersion, adding dopamine, reacting, washing the obtained reaction product, ultrasonically dispersing it in a solvent, assembling an orderly nanowire film using the Langmuir-Blodgett assembly method, and then soaking it in a potassium hydroxide solution and taking it out. This method can regulate the spacing between nanomaterials at a microscopic scale and can be prepared on a large scale.

[0033] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for regulating the spacing of orderly arranged nanowires, comprising the following steps: Silver nanowires of uniform size are prepared, washed, and the pH value is adjusted after dispersion, and then dopamine is added to react, and the reaction time is 5.5 to 6.5 hours. The obtained reaction product is washed, ultrasonically dispersed in a solvent, and the solvent includes N, N-dimethylformamide and chloroform. An ordered nanowire film is assembled using a Langmuir-Blodgett assembly method, and then immersed in a potassium hydroxide solution and taken out; The mass ratio of the silver nanowires to dopamine is 14:1-10; the pH value is adjusted using tris(hydroxymethyl)aminomethane; the mass ratio of tris(hydroxymethyl)aminomethane to dopamine is 2:(1-10); The spacing between nanowires in the ordered nanowire film is 8 to 50 nm.

2. The method according to claim 1, characterized in that The concentration of the potassium hydroxide solution is 0.9-1.1 mol / L.

3. The method according to claim 1, characterized in that The soaking time is 2.5 to 3.5 minutes.

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