CN103240422A - Method for preparing composite heterostructure of zinc oxide nano rods and silver micron plate - Google Patents

Abstract

The invention relates to a method for preparing a zinc oxide nanorod-silver microdisk composite heterogeneous structure. In the water-formamide solution reaction system of silver nitrate and ascorbic acid, dextran sodium sulfate is used as a regulator to prepare silver microdiscs with holes. plate; then deposit the zinc oxide seed crystal on the silver micro plate, and then spin-coat the silver plate with the seed crystal on the conductive glass sheet, wash and dry it, and place it in the ethanol of hexamethylenetetramine and zinc nitrate The silver microdisk zinc oxide nanorod array is grown in the solution, and the product is obtained after fully washing with water and drying naturally. The product prepared by the present invention is an advanced heterogeneous composite structure in which zinc oxide nanorod arrays are grown on silver microdiscs with holes, wherein the diameter of the silver microdiscs is ~4 microns, and the zinc oxide nanorod arrays have an adjustable size and structure. The preparation method has controllable structure, good repeatability, stable product properties and superior photocatalytic performance.

Description

Method for preparing zinc oxide nanorod-silver microdisk composite heterostructure

technical field

The invention relates to a method for preparing a structure-controllable semiconductor-metal novel composite material, in particular to a method for preparing an advanced composite heterostructure of zinc oxide nanorods-silver microdisks.

Background technique

Nanocomposites with heterogeneous structures can obtain novel physical and chemical properties and multifunctional properties that single materials do not have, so they have broad application prospects in many fields "Synthesis of Branched'nanotrees'by Controlled Seeding of Multiple Branching Events"[ Dick, KA; Deppert, K.; Larsson, MW; Martensson, T.; Seifert, W.; Wallenberg, LR; Samuelson, L. Nat. Mater. 3, 380-384. (2004)]. Among them, metal-semiconductor heterojunction composites have unique optical, electrical, and magnetic properties. Taking noble metals (such as Ag) and wide-gap oxide semiconductors (ZnO) as examples, due to the unique surface plasmon resonance effect (Surface Plasmon Resonance, SPR) of noble metals, the metal-semiconductor composite material after compounding noble metals can realize the detection of visible light. Response to "Ultrafast Plasmon-Induced Electron Transfer from Gold Nanodots into TiO ₂ Nanoparticles" [Furube, A., Du, L., Hara, K., Katoh, R. and Tachiya, MJ Am.Chem.Soc.129, 14852-14853 .(2007)]; moreover, the phenomenon of interface charge separation formed by noble metals and semiconductors due to different Fermi levels "Catalysis with TiO ₂ /Gold Nanocomposites.Effect of Metal Particle Size on the Fermi Level Equilibration" [Subramanian, V., Wolf, EEand Kamat, PV.J.Am.Chem.Soc., 126, 4943-4950.(2004)], the composite material will have higher photoelectric activity.

Most of the noble metal-zinc oxide composite materials prepared so far are (a) the noble metal is deposited in situ on the surface of the semiconductor material or (b) dispersed in the semiconductor material, and these simple composite structures have some disadvantages. The first is that the composite material has a narrow range of light absorption: the previously reported noble metal-semiconductor composite materials respond to light mainly in the ultraviolet (<400nm) and part of the visible light region (500-700nm), and the response to infrared light is very limited. (700-2500nm), which will directly affect the ability of the material to utilize long-wavelength light; secondly, the charge transport capacity in the metal-semiconductor composite structure is low, and the charge recombination rate is high: as described in (a) and (b) above In this case, because the metal or semiconductor particles are isolated from each other, there is no effective way for photogenerated electrons and holes to be efficiently transported and released, and the dense structure of the composite material is not conducive to the penetration and adsorption of electrons and hole acceptors, resulting in The chance of charge recombination increases and the catalytic activity decreases. In response to the above problems and analysis, we designed a new nano-synthesis route, using seed crystal deposition and orientation growth technology, to prepare a semiconductor-noble metal (zinc oxide nanorod-silver microdisk) based on one-dimensional and two-dimensional nanostructure elements. The heterogeneous composite structure is expected to realize the broad-spectrum absorption and high-efficiency electron transport of the material at the same time.

Contents of the invention

The purpose of the present invention can be achieved through the following technical solutions: the purpose of the present invention is to overcome the lack of material performance caused by the current semiconductor-metal composite material due to structural defects, and prepare an oxide compound with special structure and performance through a new synthesis method. Advanced heterogeneous composites of zinc nanorods-silver microdisks.

A method for preparing a zinc oxide nanorod-silver microdisc composite heterostructure, comprising the following steps:

(1) Weigh dextran sodium sulfate and dissolve it in the mixed solution of water and formamide, then successively add ascorbic acid and silver nitrate of equimolar concentration into the mixed solution under stirring, and then stand at room temperature for 24 hours to obtain For the silver microdisc product with holes, the product is centrifuged, washed and dried, then soaked in a 0.1 g/L polyvinylpyrrolidone aqueous solution for 4 hours, and the polyvinylpyrrolidone is adsorbed on the silver disc;

(2) Anhydrous zinc acetate is dissolved in dehydrated alcohol, is mixed with the solution of 10 mmol/liter, and the ethanolic solution of the potassium hydroxide that concentration is 30 mmol/liter joins in the above-mentioned solution dropwise, at 60 Continue stirring for 2 hours at °C to prepare a zinc oxide seed solution;

(3) Disperse the silver microdisks adsorbed by polyvinylpyrrolidone in step (1) into the zinc oxide seed crystal solution in step (2), soak for 4 hours, then spin-coat the silver microdiscs adsorbed with zinc oxide seed crystals on the conductive surface On a glass slide, dry in an oven for 1 hour to remove ethanol;

(4) Place the conductive glass sheet adsorbed with zinc oxide seeds in a mixed aqueous solution of zinc nitrate hexahydrate and hexamethylenetetramine at an equimolar concentration, and control the reaction temperature to 85°C to grow zinc oxide nanorods , take out the substrate, wash it, and dry it to obtain a zinc oxide nanorod-silver microdisc advanced heterogeneous composite structure.

The volume ratio of water to formamide in the mixed solution described in step (1) is 5:(4-5), and the concentration of dextran sodium sulfate in the mixed solution is 0.01 g/ml.

The molar concentration of ascorbic acid and silver nitrate described in step (1) is 0.2 mol/liter, and the ascorbic acid and silver nitrate mol ratio of adding are 1: 1; The concentration of ascorbic acid and silver nitrate in mixed solution is 2 mmol/l Lift.

The molecular weight of dextran sodium sulfate described in step (1) is 40000, and the molecular weight of described polyvinylpyrrolidone is 12000.

The volume ratio of the ethanol solution of anhydrous zinc acetate and the ethanol solution of potassium hydroxide in step (2) is (1.8-2): 1.

The mol ratio of zinc nitrate hexahydrate and hexamethylenetetramine described in the step (4) is 1: 1; The concentration of zinc nitrate hexahydrate and hexamethylenetetramine in the mixed aqueous solution is 2～10 mmol/L.

The reaction time for the growth of zinc oxide nanorods in step (4) is 2 to 24 hours.

The diameter of the silver microdisk in the prepared zinc oxide nanorod-silver microdisk advanced heterogeneous composite structure is 1-4 microns, the rod diameter of the zinc oxide nanorod is 20-200 nanometers, the length is 100-1800 nanometers, and the shape is tubular , tapered or rod-shaped.

Compared with the prior art, the zinc oxide nanorod-silver microdisc advanced heterogeneous composite structure synthesized by the method adopted in the present invention has good crystallization; the zinc oxide nanorod array endows the material with a high specific surface area and an open structure, which is beneficial to Adsorption and exchange with environmental substances; the plasmon resonance effect of silver microdisks enables the composite material to absorb visible light, broadening the absorption spectrum of the material; at the same time, zinc oxide nanorods and silver nanodisks act as one-dimensional and two-dimensional charge transport approach, so that the composite material has unique electron stereoscopic transport characteristics; due to the above-mentioned advantages in structure and composition, ZnO nanorods-silver discs showed superior photoelectric activity in the test of photocatalytic degradation of pollutants. Moreover, the preparation method is controllable, the repeatability is good, and the product properties are stable, and can be widely used as photocatalysts, electrode materials for solar cells and lithium batteries, high-efficiency electrode materials for microelectronic devices and sensors, and the like.

Description of drawings

Figure 1 is the scanning electron micrograph (A-B), transmission electron microscope (C-D), X-ray diffraction pattern (E) and scanning electron micrograph (F-G) of the silver microdisk with holes before zinc oxide seed crystal deposition and zinc oxide seed crystal deposition .

Figure 2 is the scanning electron micrographs (A, C-D) and X-ray diffraction pattern (B) of the advanced heterogeneous composite structure of the ZnO array grown on the silver microdisk and the low magnification (E) and high magnification of a single ZnO nanorod Resolution (F) TEM photo.

Fig. 3 is a scanning electron micrograph of an advanced heterogeneous composite structure in which zinc oxide arrays are grown on silver microdisks. Wherein (A-B): the growth time is 2 hours; (C-E): the growth time is 24 hours.

Detailed ways

A method for preparing a zinc oxide nanorod-silver microdisc composite heterostructure, comprising the following steps:

(1) Take the dextran sodium sulfate that molecular weight is 40000 and dissolve in the mixed solution that water and formamide are 5: (4-5) by volume ratio, the concentration of dextran sodium sulfate in the mixed solution is 0.01 g/ml, and then add equimolar concentration and equal volume of ascorbic acid and silver nitrate into the mixed solution successively under stirring, the molar concentration of ascorbic acid and silver nitrate is 0.2 mol/liter, and the concentration of ascorbic acid and silver nitrate in the mixed solution is equal to 2 mmol/liter, then stand at room temperature for 24 hours to obtain a silver microdisc product with holes, the product is centrifuged and washed with water and dried, then soaked in an aqueous solution of 0.1 g/liter of polyvinylpyrrolidone (molecular weight is 12000) 4 hours, the polyvinylpyrrolidone is adsorbed on the silver plate;

(2) Anhydrous zinc acetate is dissolved in dehydrated alcohol, is mixed with the solution of 10 mmol/liter, and the ethanol solution of the potassium hydroxide that concentration is 30 mmol/liter is added dropwise in the above-mentioned solution, anhydrous The volume ratio of the ethanol solution of zinc acetate to the ethanol solution of potassium hydroxide is (1.8-2): 1, and then continuously stirred at 60°C for 2 hours to prepare a zinc oxide seed solution;

(3) Disperse the silver microdisks adsorbed by polyvinylpyrrolidone in step (1) into the zinc oxide seed crystal solution in step (2), soak for 4 hours, then spin-coat the silver microdiscs adsorbed with zinc oxide seed crystals on the conductive surface On a glass slide, dry in an oven for 1 hour to remove ethanol;

(4) The conductive glass sheet that is adsorbed with the zinc oxide seed crystal is placed in the mixed aqueous solution of zinc nitrate hexahydrate and hexamethylenetetramine of equimolar concentration, the concentration of zinc nitrate hexahydrate and hexamethylenetetramine The molar ratio is 1:1, the concentration of zinc nitrate hexahydrate and hexamethylenetetramine in the mixed aqueous solution is 2-10 mmol/L, and the reaction temperature is controlled at 85°C to grow zinc oxide nanorods for 2-24 hours , take out the substrate, wash, and dry to obtain a zinc oxide nanorod-silver microdisc advanced heterogeneous composite structure, wherein the diameter of the silver microdisk is 1-4 microns, the diameter of the zinc oxide nanorod is 20-200 nanometers, and the length It is 100-1800 nanometers, and the shape is tubular, pointed or rod-shaped.

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

Example 1

Weigh 0.1 gram of dextran sodium sulfate (molecular weight 40,000) and dissolve it in the mixed solution of water and formamide, then mix 0.1 milliliter of ascorbic acid and 0.1 milliliter of silver nitrate with equimolar concentration (0.2 mol/liter) successively under stirring Add it into the mixed solution and let it stand at room temperature for 24 hours to prepare a silver microdisc product with holes. The product was centrifuged, washed with water, dried and soaked in 0.1 g/L polyvinylpyrrolidone (PVP, molecular weight 12000) aqueous solution for 4 hours, so that PVP was adsorbed on the silver plate. At the same time, another 125 milliliters of 10 mmol/L zinc acetate in ethanol was added dropwise to 65 mL of 30 mmol/L potassium hydroxide in ethanol, and the mixture was continuously stirred at 60° C. for 2 hours. A zinc oxide seed solution is prepared. Then the PVP-treated silver microdiscs were dispersed into the above-mentioned zinc oxide seed crystal solution, soaked for 4 hours to fully adsorb the zinc oxide crystal seeds (its microstructure is shown in Figure 1). Then spin-coat the silver disc with zinc oxide seed crystals adsorbed on the conductive glass, place it in an oven to dry for 1 hour, and then place it in 20 ml of 10 mmol/L zinc nitrate hexahydrate and hexamethylenetetramine aqueous solution In the method, zinc oxide nanorods are grown, and after the reaction is carried out at 85° C. for 8 hours, the substrate is taken out, cleaned, and dried to obtain a zinc oxide nanorod-silver microdisk advanced heterogeneous composite structure. The ZnO nanorods in this product were ~80 nm in diameter and 1-1.2 microns in length (Figure 2).

Example 2

Weigh 0.1 gram of dextran sodium sulfate (molecular weight 40,000) and dissolve it in the mixed solution of water and formamide, then mix 0.1 milliliter of ascorbic acid and 0.1 milliliter of silver nitrate with equimolar concentration (0.2 mol/liter) successively under stirring Add it into the mixed solution and let it stand at room temperature for 24 hours to prepare a silver microdisc product with holes. The product was centrifuged, washed with water, dried and soaked in 0.1 g/L polyvinylpyrrolidone (PVP, molecular weight 12000) aqueous solution for 4 hours, so that PVP was adsorbed on the silver plate. At the same time, another 125 milliliters of 10 mmol/L zinc acetate in ethanol was added dropwise to 65 mL of 30 mmol/L potassium hydroxide in ethanol, and the mixture was continuously stirred at 60° C. for 2 hours. A zinc oxide seed solution is prepared. Then the PVP-treated silver microdiscs were dispersed into the above-mentioned zinc oxide seed crystal solution, soaked for 4 hours to fully adsorb the zinc oxide seed crystals. Then spin-coat the silver disc with zinc oxide seed crystals adsorbed on the conductive glass, place it in an oven to dry for 1 hour, and then place it in 20 ml of 10 mmol/L zinc nitrate hexahydrate and hexamethylenetetramine aqueous solution In the method, zinc oxide nanorods are grown, and after the reaction is carried out at 85° C. for 2 hours, the substrate is taken out, washed, and dried to obtain a zinc oxide nanorod-silver microdisk advanced heterogeneous composite structure. The ZnO nanorods in this product have a diameter of ~30 nm and a length of 600-800 nm (A-B in Figure 3).

Example 3

Weigh 0.1 gram of dextran sodium sulfate (molecular weight 40,000) and dissolve it in the mixed solution of water and formamide, then mix 0.1 milliliter of ascorbic acid and 0.1 milliliter of silver nitrate with equimolar concentration (0.2 mol/liter) successively under stirring Add it into the mixed solution and let it stand at room temperature for 24 hours to prepare a silver microdisc product with holes. The product was centrifuged, washed with water, dried and soaked in 0.1 g/L polyvinylpyrrolidone (PVP, molecular weight 12000) aqueous solution for 4 hours, so that PVP was adsorbed on the silver plate. At the same time, another 125 milliliters of 10 mmol/L zinc acetate in ethanol was added dropwise to 65 mL of 30 mmol/L potassium hydroxide in ethanol, and the mixture was continuously stirred at 60° C. for 2 hours. A zinc oxide seed solution is prepared. Then the PVP-treated silver microdiscs were dispersed into the zinc oxide seed crystal solution, soaked for 4 hours to fully absorb the zinc oxide seed crystals. Then spin-coat the silver disc with zinc oxide seed crystals adsorbed on the conductive glass, place it in an oven to dry for 1 hour, and then place it in 20 ml of 10 mmol/L zinc nitrate hexahydrate and hexamethylenetetramine aqueous solution In the process, zinc oxide nanorods are grown, and after the reaction is carried out at 85° C. for 24 hours, the substrate is taken out, cleaned, and dried to obtain a zinc oxide nanorod-silver microdisk advanced heterogeneous composite structure. The ZnO nanorods in this product have a diameter of ~150 nm and a length of 1.8 microns, and the nanorods have tapered tips (C-E in Figure 3), a feature that is expected to find important applications in field emission.

Example 4

A method for the advanced heterogeneous composite structure of zinc oxide nanorods-silver microdisks with holes, the method comprising the following steps:

1) Take by weighing 0.1 gram of dextran sodium sulfate (molecular weight 40000) and dissolve it in the mixed solution of water and formamide, then successively mix 0.1 milliliter of ascorbic acid and 0.1 milliliter of ascorbic acid of equimolar concentration (0.2 mol/liter) and 0.1 milliliter of Silver nitrate was added to the mixed solution, and then left to stand at room temperature for 24 hours to obtain a silver microdisc product with holes. Centrifuge the product, wash it with water three times, soak it in 0.1 g/L polyvinylpyrrolidone (PVP, molecular weight 12000) aqueous solution for 4 hours after drying, so that PVP is adsorbed on the silver plate.

(2) A certain amount of anhydrous zinc acetate was dissolved in 125 ml of absolute ethanol to prepare a solution of 10 mmol/L. Next, 65 ml of 30 mmol/L potassium hydroxide ethanol solution was added dropwise to the above solution, and the stirring was continued at 60° C. for 2 hours to prepare a zinc oxide seed solution;

(3) Disperse the PVP-treated silver microdiscs in step (1) into the zinc oxide seed crystal solution in step (2), soak for 4 hours to fully absorb the zinc oxide seed crystals. Then spin-coat the silver disk with zinc oxide seed crystals adsorbed on the conductive glass sheet, and dry it in an oven for 1 hour to remove ethanol before use;

(4) the conductive glass sheet that is adsorbed with zinc oxide seed crystal is placed in the aqueous solution of zinc nitrate hexahydrate and hexamethylenetetramine of 20 milliliters of 2 mmoles/liter, carries out the growth of zinc oxide nanorod, reacts in After 5 hours at 85° C., the substrate was taken out, washed, and dried to obtain a zinc oxide nanorod-silver microdisk advanced heterogeneous composite structure. The zinc oxide nanorods in the product have a diameter of 50-100 nanometers and a length of 100-200 nanometers, and the tips of the nanorods are in a concave bowl-shaped structure.

Example 5

A method for the advanced heterogeneous composite structure of zinc oxide nanorods-silver microdisks with holes, the method comprising the following steps:

1) Take by weighing 0.1 gram of dextran sodium sulfate (molecular weight 40000) and dissolve it in the mixed solution of water and formamide, then successively mix 0.1 milliliter of ascorbic acid and 0.1 milliliter of ascorbic acid of equimolar concentration (0.2 mol/liter) and 0.1 milliliter of Silver nitrate was added to the mixed solution, and then left to stand at room temperature for 24 hours to obtain a silver microdisc product with holes. Centrifuge the product, wash it with water three times, soak it in 0.1 g/L polyvinylpyrrolidone (PVP, molecular weight 12000) aqueous solution for 4 hours after drying, so that PVP is adsorbed on the silver plate.

(2) A certain amount of anhydrous zinc acetate was dissolved in 125 ml of absolute ethanol to prepare a solution of 10 mmol/L. Next, 65 ml of 30 mmol/L potassium hydroxide ethanol solution was added dropwise to the above solution, and the stirring was continued at 60° C. for 2 hours to prepare a zinc oxide seed solution;

(3) Disperse the PVP-treated silver microdiscs in step (1) into the zinc oxide seed crystal solution in step (2), soak for 4 hours to fully absorb the zinc oxide seed crystals. Then spin-coat the silver disk with zinc oxide seed crystals adsorbed on the conductive glass sheet, and dry it in an oven for 1 hour to remove ethanol before use;

(4) the conductive glass sheet that is adsorbed with zinc oxide seed crystal is placed in the aqueous solution of zinc nitrate hexahydrate and hexamethylenetetramine of 20 milliliters of 5 mmoles/liter, carries out the growth of zinc oxide nanorod, reacts in After 5 hours at 85° C., the substrate was taken out, washed, and dried to obtain a zinc oxide nanorod-silver microdisk advanced heterogeneous composite structure. The diameter of the zinc oxide nanorod in the product is 20-150 nanometers, the length is 150-300 nanometers, and the tip of the nanorod is in a tubular structure.

Compared with the prior art, the synthesis method adopted in the present invention is an advanced heterogeneous composite structure (Fig. 2-3) in which zinc oxide nanorod arrays are grown on silver microdisks with holes, and the diameter of the silver microdisks is ~4 Micron, the diameter of the nanorod in the zinc oxide nanorod array is 20-200 nanometers, the length is 100-1800 nanometers, and the shape is tubular, pointed and rod-shaped. The preparation method has controllable structure, good repeatability, stable product properties and superior photocatalytic performance. Therefore, it can be used in many fields such as photocatalysis, solar cells, lithium batteries, microelectronic devices, and gas sensing.

Claims (8)

1. prepare the method for zinc oxide nano rod-Yin micron dish composite heterogenous junction structure, it is characterized in that this method may further comprise the steps:

(1) taking by weighing dextran sulfate sodium is dissolved in the mixed solution of water and formamide, then under agitation successively will wait ascorbic acid and the silver nitrate of molar concentration to add in the mixed solution, left standstill 24 hours in room temperature then, make silver micron dish product with holes, product centrifugation and washing were soaked in after drying in the aqueous solution of polyvinylpyrrolidone of 0.1 grams per liter 4 hours, polyvinylpyrrolidone is adsorbed on the silver plate;

(2) anhydrous zinc acetate is dissolved in the absolute ethyl alcohol, be mixed with 10 mMs/liter solution, with concentration be 30 mMs/liter the ethanolic solution of potassium hydroxide dropwise join in the above-mentioned solution, continue down to stir 2 hours in 60 ℃, prepare zinc oxide crystal seed solution;

(3) the silver micron with polyvinylpyrrolidone absorption in the step (1) coils in the zinc oxide crystal seed solution that is distributed in the step (2), soaked 4 hours, then the silver plate that is adsorbed with zinc oxide crystal seed is spun on the electro-conductive glass sheet, removed ethanol in 1 hour at oven drying;

(4) the electro-conductive glass sheet that will be adsorbed with zinc oxide crystal seed such as places at the zinc nitrate hexahydrate of molar concentration and the mixed aqueous solution of six methylene tetramines, the control reaction temperature is 85 ℃ of growths of carrying out zinc oxide nano rod, take out substrate, clean, drying namely obtains zinc oxide nano rod-Yin micron and coils senior Heterogeneous Composite structure.

2. the method for preparing zinc oxide nano rod-Yin micron dish composite heterogenous junction structure according to claim 1, it is characterized in that, the volume ratio of water and formamide is 5 in the mixed solution described in the step (1): (4-5), the concentration of dextran sulfate sodium in mixed solution is 0.01 grams per milliliter.

3. the method for preparing zinc oxide nano rod-Yin micron dish composite heterogenous junction structure according to claim 1, it is characterized in that, the molar concentration of the ascorbic acid described in the step (1) and silver nitrate is 0.2 mol, and the ascorbic acid of adding and silver nitrate mol ratio are 1: 1; Ascorbic acid and the silver nitrate concentration in mixed solution be 2 mMs/liter.

4. the method for preparing zinc oxide nano rod-Yin micron dish composite heterogenous junction structure according to claim 1 is characterized in that the molecular weight of the dextran sulfate sodium described in the step (1) is 40000, and the molecular weight of described polyvinylpyrrolidone is 12000.

5. the method for preparing zinc oxide nano rod-Yin micron dish composite heterogenous junction structure according to claim 1 is characterized in that, the volume ratio of the ethanolic solution of the ethanolic solution of anhydrous zinc acetate and potassium hydroxide is (1.8-2) in the step (2): 1.

6. the method for preparing zinc oxide nano rod-Yin micron dish composite heterogenous junction structure according to claim 1 is characterized in that the mol ratio of the zinc nitrate hexahydrate described in the step (4) and six methylene tetramines is 1: 1; Zinc nitrate hexahydrate and the concentration of six methylene tetramines in mixed aqueous solution be 2～10 mMs/liter.

7. the method for preparing zinc oxide nano rod-Yin micron dish composite heterogenous junction structure according to claim 1 is characterized in that, the reaction time of zinc oxide nano rod growth is 2～24 hours in the step (4).

8. the method for preparing zinc oxide nano rod-Yin micron dish composite heterogenous junction structure according to claim 1, it is characterized in that, the diameter that the zinc oxide nano rod for preparing-Yin micron coils silver micron dish in the senior Heterogeneous Composite structure is 1～4 micron, the excellent diameter of zinc oxide nano rod is 20～200 nanometers, length is the 100-1800 nanometer, is shaped as tubulose, cone-shaped or bar-shaped.

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