TWI495617B - A method for preparing powdered zinc oxide nanowires - Google Patents

Description

Method for preparing powder type zinc oxide nanowire

The invention relates to a method for preparing a powder type zinc oxide nanowire, in particular to a two-stage thermal oxidation treatment, and a powder type oxidation for heating and cooling treatment by setting a position of a zinc-containing metal sheet in a high-temperature furnace. The method of zinc nanowires.

Nowadays, there are cases of powder type zinc oxide nanowire preparation and application on sensors and photocatalysts, but the preparation process is complicated and expensive. Presented by Chinese scholars Y. Zhang, K. Yu, D. Jiang, Z. Zhu, H. Geng, and L. Luo, Zinc oxide nanorod and nanowire for humidity sensor, Applied Surface Science 242, 212-217 (2005) In this document, a zinc oxide nanowire has been grown on a tantalum substrate by a gas-liquid-solid method in which an equal amount of zinc oxide powder and graphite powder are mixed in a quartz boat and placed. In the quartz tube, argon and oxygen are introduced, and the reaction is carried out at a temperature of 450 ° C to 600 ° C for one hour, and then the system is naturally lowered to room temperature, that is, the zinc oxide nanowire is grown on the prepared substrate. However, this system directly grows the zinc oxide nanowire on the sparse electrode, and can only make a small area sensor and requires the use of two gases.

Chinese scholars Q.Qi, T.Zhang, Q.Yu, R.Wang, Y.Zeng, L.Liu, and H.Yang, Properties of humidity sensing ZnO nanorods-base sensor fabricated by screen-printing, Sensors and Actuators B In this document proposed by 133, 638-643 (2008), a zinc oxide nano column as a flower shape is synthesized by a wet chemical method as a humidity sensor material. This wet chemical method was to mix a 0.05 M aqueous solution of zinc nitrate (Zn(NO ₃ ) ₂ ) with an aqueous solution of 0.05 M hexamethylenetetramine (CH ₂ ) ₆ N ₄ ) and stir for 5 minutes. The mixed solution is then heated at a temperature of 90 ° C for 3 hours, then the white product is separated, washed with deionized water and alcohol, and heated to 60 ° C in air, like a flower-shaped zinc oxide nano column. It can be synthesized. This zinc oxide nano column process is complicated and time consuming, which is a major drawback.

In the literature proposed by the Chinese scholars WYWu, JMTing, and PJHuang, Electrospun ZnO nanowires as gas sensors for ethanol detection, Nanoscale Res Lett 4, 513-517 (2009), electrospinning is utilized. The method of synthesizing zinc oxide nanowires as a resistive alcohol sensor material. The method first prepares a gel of zinc acetate (Zinc Acetate) and polyvinyl acetate (PVA), and the gel is placed in a syringe. The syringe is connected to a high voltage (15 kV) power source as a positive electrode. The negative electrode is a crucible wafer on which an elongated electrode is formed and placed on an aluminum foil. After supplying a voltage of 15 kV, the electrically converted nanowire polymer was formed on a tantalum wafer, and then subjected to a calcination method at 600 ° C for 7 hours to convert the nanowire polymer into an inorganic zinc oxide nanowire. The process of this zinc oxide nanowire is also very complicated and time consuming.

In addition, the Republic of China Patent No. TW I242540 discloses a method for producing a zinc oxide nanowire by adding zinc powder having a diameter of 10 μm or less to a reaction tank, and introducing argon gas into the reaction tank to make a reaction tank. Continue to rotate and stir the zinc powder to prevent oxidation of the zinc powder; after heating to 400 °C, stop the entry of argon and steam. After the gas is continuously heated to 500 ° C, the temperature is maintained at a reaction temperature, and the reaction temperature may be 400 ° C to 500 ° C to reduce the reaction between the zinc powder and the water vapor to generate a zinc oxide nanowire body. In this method, an alternate combination of an inert gas and water vapor is required, so that the hardware piping is complicated and unpredictable in preparation time, and there is still room for improvement.

The main object of the present invention is to provide a method for preparing a powder type zinc oxide nanowire, which uses two-stage heating to thermally oxidize a zinc-containing metal sheet in air, and then continues to perform high temperature treatment under vacuum to synthesize A powdered zinc oxide nanowire is produced.

A secondary object of the present invention is to provide a method for preparing a powder type zinc oxide nanowire, which preliminarily reacts the surface of the zinc-containing metal sheet with an organic acid and cools it before heating the zinc-containing metal sheet to allow Nai The rice noodles are formed after high temperature treatment.

Another object of the present invention is to provide a method for preparing a powder type zinc oxide nanowire which controls the placement position of a zinc-containing metal sheet in a high temperature furnace to ensure that the zinc-containing metal sheet can be sequentially placed in a high temperature furnace. Apply cooling and heat treatment.

In order to achieve the above object, the present invention discloses a method for preparing a powder type zinc oxide nanowire, the method comprising: immersing a zinc-containing metal sheet in an organic acid solution; and disposing the zinc-containing metal sheet to a Above the quartz plate; placing the quartz plate in a high temperature furnace; heating the zinc-containing metal piece to a first temperature, causing the zinc-containing metal piece to be in contact with the air in the high-temperature furnace to oxidize to form a surface of zinc oxide The vacuum is applied to continue heating the zinc-containing metal sheet to a second temperature under vacuum to oxidize the zinc oxide by annealing; and after cooling, the powder type zinc oxide nanowire can be synthesized. The prepared powder type zinc oxide nanowire can be further utilized, for example, by coating. It can be attached to the electrode to form a high-sensitivity sensing element, and can also be used as a material for a piezoelectric micro-generator, or as a photocatalyst for air cleaners and tamper-proof materials.

1‧‧‧High temperature furnace

2‧‧‧Quartz tube

21‧‧‧Endpoint

3‧‧‧Quartz plate

4‧‧‧Zinc-containing metal sheet

5‧‧‧Cooling device

6‧‧‧Exhaust device

S1‧‧‧Step one

S2‧‧‧Step 2

S3‧‧‧Step three

S4‧‧‧Step four

S5‧‧‧Step five

S6‧‧‧Step six

The first figure is a flow chart of the steps of the present invention; the second figure is a schematic diagram of placing a zinc-containing metal sheet in a high-temperature furnace in the present invention; and a third figure: it is an overall operation in the present invention. Schematic diagram of the equipment.

For a better understanding and understanding of the features and advantages of the present invention, the preferred embodiments and the detailed description are as follows: First, please refer to the first figure, which is the present invention. The operation step comprises: step S1: soaking a zinc-containing metal piece in an organic acid solution; step S2: dislocating the zinc-containing metal piece onto a quartz plate; and step S3: placing the quartz plate in a In the high temperature furnace; step S4: heating the zinc-containing metal sheet to a first temperature, causing the zinc-containing metal sheet to be oxidized by contacting with air in the high-temperature furnace to form a surface of zinc oxide; step S5: vacuuming The zinc-containing metal sheet is further heated to a second temperature under vacuum to cause the zinc oxide to be annealed to be cracked; and in step S6: after the temperature is lowered, a stable powder type zinc oxide nanowire is formed.

With reference to the above steps, please refer to the operation equipment shown in the second figure and the third figure. When preparing the powder type zinc oxide nanowire, the zinc-based metal sheet 4 is taken as the material, and the zinc-containing metal sheet 4 is used. In the case of a thin sheet, the area can be adjusted as needed, thus facilitating mass production. The material is not limited to a pure zinc metal sheet, and other metal sheets such as zinc-carbon alloy sheets containing zinc may be used as long as they can react with oxygen to synthesize zinc oxide crystals during thermal oxidation. Just fine. The present invention first immerses the zinc-containing metal sheet 1 in an organic acid solution before placing it in the quartz tube 2. The type of the organic acid is not particularly limited, and the present invention is 0.3 M oxalic acid (C ₂ H ₂ O ₄ ) was used as a material, and after soaking for about 10 minutes, it was transferred to a quartz plate 3.

Next, the quartz plate 3 is placed in the high temperature furnace 1 to be heated. The high temperature furnace 1 heats the quartz tube 2 penetrating the center thereof, so that the quartz plate 3 is placed in the quartz tube 2, and the cooling device 5 is provided at both ends of the quartz tube 2, and has a function of cooling. As shown in the third figure, a portion of both ends of the quartz tube 2 is exposed outside the high temperature furnace 1, and the cooling device 5 is located at the end point 21 of the quartz tube 2.

When the quartz plate 3 is placed in the high temperature furnace 1, the quartz plate 3 is placed in the quartz tube 2, and the distance from the cooling device 5 is also important; if the operator places the quartz plate 3 In the center of the high temperature furnace 1, that is, the position farthest from the cooling device 5 at both ends, the failure rate is greatly increased, because the present invention requires cooling treatment before heating, so the position of the quartz plate 3 is close to the cooling device 5, However, it is not exposed to the outside of the high temperature furnace 1 to achieve a balance between cooling and subsequent heat treatment.

After the quartz plate 3 is placed, the process proceeds to step S4, that is, the zinc-containing metal piece 4 is heated to a first temperature, which is not high as long as it can be higher than the melting point of the organic acid used. Taking the melting point of oxalic acid as an example, the first temperature is controlled to be greater than 190 ° C, and the purpose is to accelerate the surface of the zinc-containing metal sheet 4 to occur in the air. The process of oxidation to form zinc oxide. In order to achieve the purpose of oxidation, the quartz tube 2 has not been evacuated to a vacuum state during this stage.

After the quartz plate 3 and the zinc-containing metal piece 4 are indirectly heated in the high-temperature furnace through the heating quartz tube 2 to the first temperature for about several tens of minutes, the process proceeds to step S5, and the inside of the quartz tube 2 is evacuated and under vacuum. Heating of the zinc-containing metal sheet 4 to a second temperature is continued. The second temperature is above 680 ° C, so that the surface on which the zinc oxide is formed is cleaved, and then cooled back to room temperature to synthesize a stable powder type zinc oxide, which is a structure of a nanowire.

The cooling process after the second temperature annealing process can be cooled to room temperature by natural cooling without limiting the operation of the cooling device 5.

The invention has high efficiency, and the whole time for heating the zinc-containing metal sheet 4 is not more than 50 minutes, and the preparation of the powder type zinc oxide nano-wire can be completed in one hour, which is not complicated in the operation of the deposition method in the past and waste time. . The prepared powder type zinc oxide nanowire can be further coated with a solution on a desired substrate as a sensor element, a generator element or a photocatalytic element. The powder type zinc oxide nanowire can be used as a high-sensitivity sensor element because of its many surface oxygen defects and oxygen cavities, and the photo-degradation efficiency of the dye is also relatively high, which can be combined with a smart circuit design. Used in a variety of mechanical equipment, such as dehumidifiers, air purifiers, gas explosion-proof devices or gas detectors.

The method for preparing a powder type zinc oxide nanowire disclosed by the present invention is subjected to two-stage thermal oxidation, and is skillfully controlled by a zinc-containing metal sheet in a high-temperature furnace to control the zinc-containing metal sheet. Heating and cooling treatment allows the zinc oxide nanowire to be synthesized quickly, with efficiency, quality and cost. The present invention undoubtedly provides an economical and practical method for preparing a powder type zinc oxide nanowire.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and the variations, modifications, and modifications of the shapes, structures, features, and spirits described in the claims of the present invention. All should be included in the scope of the patent application of the present invention.

S1‧‧‧Step one

S2‧‧‧Step 2

S3‧‧‧Step three

S4‧‧‧Step four

S5‧‧‧Step five

S6‧‧‧Step six

Claims (9)

A method for preparing a powder type zinc oxide nanowire, the method comprising: immersing a zinc-containing metal sheet in an organic acid solution; disposing the zinc-containing metal sheet onto a quartz plate; and placing the quartz plate on a high temperature furnace; heating the zinc-containing metal sheet to a first temperature, causing the zinc-containing metal sheet to be oxidized by contact with air in the high-temperature furnace to form a surface of zinc oxide, the first temperature being below 190 degrees Celsius And vacuuming and continuing to heat the zinc-containing metal sheet to a second temperature under vacuum, and oxidizing the zinc oxide to form a powder type zinc oxide nanowire, the second temperature being 680 degrees Celsius or more. The method of claim 1, wherein the first temperature is greater than a melting point of the organic acid contained in the organic acid solution. The method of claim 1, wherein the high temperature furnace has a quartz tube, a portion of both ends of the quartz tube is exposed outside the high temperature furnace, and a cooling device is located at an end of the quartz tube. The method of claim 3, wherein the quartz plate is placed in the quartz tube and is adjacent to the cooling device but is not exposed to the high temperature furnace. The method of claim 3, wherein the cooling device cools the zinc-containing metal sheet after the quartz plate is placed in the high temperature furnace. The method of claim 3, wherein the quartz tube is connected to an air extraction device that draws the interior of the quartz tube into a vacuum. The method of claim 1, wherein the organic acid is oxalic acid (C2H2O4). The method of claim 1, wherein the zinc-containing metal sheet is heated for no more than 50 minutes. The method of claim 1, wherein after the zinc oxide is lysed by annealing, the film is further cooled to room temperature to form a powder type zinc oxide nanowire.