JP3994158B2 - Molybdenum disulfide nanoflower and its production method - Google Patents
Molybdenum disulfide nanoflower and its production method Download PDFInfo
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- JP3994158B2 JP3994158B2 JP2003068297A JP2003068297A JP3994158B2 JP 3994158 B2 JP3994158 B2 JP 3994158B2 JP 2003068297 A JP2003068297 A JP 2003068297A JP 2003068297 A JP2003068297 A JP 2003068297A JP 3994158 B2 JP3994158 B2 JP 3994158B2
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- molybdenum disulfide
- nanoflowers
- molybdenum
- production method
- field emission
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【０００１】
【発明の属する技術分野】
この出願の発明は、二硫化モリブデンノフラワーに関するものである。さらに詳しくは、この出願の発明は、優れた電界放出特性を有する、電界放出用材料として有用な二硫化モリブデンナノフラワーとその製造方法に関するものである。
【０００２】
【従来の技術】
小さい曲率半径を有するナノサイズのナノチューブ、ナノワイヤー等は、その先端部に電界が集中しやすいため、電子放出材料（エミッター）として有望である。このことから、カーボンナノチューブ、針状の炭化珪素ナノロッド、タングステンナノロッド、三酸化モリブデンナノベルト等のナノ構造物について電界放出特性の検討が盛んに行われている。そして、上記ナノ構造物は、大画面のフラットパネルディスプレイへの応用に多大な関心が持たれている。
【０００３】
また、ナノチューブは、その先端が開いていると、電界放出特性が飛躍的に向上することが報告されている。
【０００４】
一方、二硫化モリブデンのナノ構造物については、電気化学的な水素の吸脱着用電極、固体潤滑剤等への応用が検討されている（たとえば、非特許文献１、２参照）。
【０００５】
【非特許文献１】
J.Chen外，ジャーナル・オブ・アメリカン・ケミカルソサイエティ(J.Am.Chem.Soc)，2001年，第123巻，第11813頁
【非特許文献２】
L.Rapoport外，ネイチャー(Nature)，1997年，第387巻，第791頁
【０００６】
【発明が解決しようとする課題】
この出願の発明は、上述の従来技術に鑑みてなされたものであり、優れた電界放出特性を有する、電界放出用材料として有用な二硫化モリブデンナノフラワーとその製造方法を提供することを解決すべき課題としている。
【０００７】
【課題を解決するための手段】
この出願の発明は、上記の課題を解決するものとして、100〜200ナノメートルの幅と数ナノメートルの厚さの花弁状構造物が数千枚集合していることを特徴とする二硫化モリブデンナノフラワー（請求項１）を提供する。
【０００８】
またこの出願の発明は、酸化モリブデン薄膜を硫黄の蒸気雰囲気中で950〜1000℃に加熱し、請求項１記載の二硫化モリブデンナノフラワーを作製することを特徴とする二硫化モリブデンナノフラワーの製造方法（請求項２）を提供する。
【０００９】
【発明の実施の形態】
この出願の発明の二硫化モリブデンナノフラワーとその製造方法は、上記のとおりの特徴を有するものであるが、以下に実施例を示し、この出願の発明の二硫化モリブデンナノフラワーとその製造方法についてさらに詳しく説明する。
【００１０】
【実施例】
グラファイト製るつぼの中に硫黄粉末を入れ、るつぼの上方約１cmのところにモリブデン箔（１０mm×１０mm×0.1mm）を配置した。これら硫黄粉末及びモリブデン箔を出発原料として赤外線照射炉を用い、モリブデン箔は950〜1000℃に、硫黄粉末は300〜350℃に２０分間加熱した。モリブデン箔が酸化されて生成した酸化モリブデンの表面の薄層が、発生した硫黄の蒸気により還元された。
【００１１】
生成物についてＸ線回折で調べた結果、格子定数ａ＝3.16Å、ｃ＝12.3Åの六方晶系の二硫化モリブデン相が形成していることが確認された。また、生成物を走査型電子顕微鏡で観察した結果、生成物は、図１（ａ）（ｂ）に示したような花状の形状をしており、大きさは数百ナノメートルであった。このナノフラワーは、数千枚の花弁状物から構成されており、一枚の花弁の大きさは、幅が約100〜200ナノメートルで、厚さが数ナノメートルであった。
【００１２】
以上のナノフラワーが付着しているモリブデン箔から少量のナノフラワーを剥がし取り、アルコールに分散して１５分間超音波処理を行った。この分散液は、次いでカーボン膜の付いた銅グリッドに滴下して乾燥させた。Ｘ線エネルギー拡散スペクトロメーターと電子エネルギー損失スペクトロメーターを付属した高分解能透過型電子顕微鏡を用い、ナノフラワーの結晶構造及び化学組成の分析を行った。ナノフラワーは、超音波処理中でも形状が破壊されず、安定であった。
【００１３】
図２に示したように、電子エネルギー損失スペクトルの測定結果から、ナノフラワーの化学組成は、モリブデン(227eV)と硫黄原子(165eV)からなることが判明した。また、電子線回折の結果から、純粋な六方晶系の二硫化モリブデン相であることが確認された。
【００１４】
図３は、代表的なナノフラワーの高分解能透過型電子顕微鏡像であるが、六方晶系の二硫化モリブデンの(002)結晶底面の縞模様が明りょうに観察される。花弁状物を構成している層の数は、先端に向かうにつれて減少し、先端部では、５層より少なく、厚さは約１〜３ナノメートルであった。
【００１５】
断面積１mm2の棒状のアルミニウム探針を陽極とし、二硫化モリブデンナノフラワーを陰極として2.0×１０-7Torrの真空中で電界放出特性を測定した。０〜1100Ｖの電圧を印加し、陽極とナノフラワー間の距離を100〜150μｍまで変化させた時の電流密度を測定した結果を図４に示した。
【００１６】
１０μＡ/cm2、１０ｍＡ/cm2の電流密度を生じさせるのに要する電圧をそれぞれ開始電圧、閾値電圧と定義すると、二硫化モリブデンナノフラワーは、開始電圧が4.5〜5.5Ｖ/μｍ、閾値電圧が7.6〜8.6Ｖ/μｍであることが判明した。このように、二硫化モリブデンナノフラワーが優れた電界放出特性を示すのは、花弁の先端が非常に薄く、かつ開いていることによる。
【００１７】
もちろん、この出願の発明は、以上の実施例によって限定されるものではない。細部については様々な態様が可能であることはいうまでもない。
【００１８】
【発明の効果】
以上詳しく説明した通り、この出願の発明によって、優れた電界放出特性を有する、電界放出用材料として有用な二硫化モリブデンナノフラワーと、これを実現する製造方法が提供される。
【図面の簡単な説明】
【図１】（ａ）（ｂ）は、それぞれ、実施例で得られた二硫化モリブデンナノフラワーの走査型電子顕微鏡像である。
【図２】実施例で得られた二硫化モリブデンナノフラワーの電子エネルギー損失スペクトルである。
【図３】実施例で得られた二硫化モリブデンナノフラワーの高分解能透過型電子顕微鏡像である。
【図４】実施例で得られた二硫化モリブデンナノフラワーの電界放出特性（電圧と電流密度の関係）を示したグラフである。[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to molybdenum disulfide noflower. More specifically, the invention of this application relates to a molybdenum disulfide nanoflower useful as a field emission material having excellent field emission characteristics and a method for producing the same.
[0002]
[Prior art]
Nano-sized nanotubes, nanowires, and the like having a small radius of curvature are promising as electron emission materials (emitters) because the electric field tends to concentrate on their tips. For this reason, field emission characteristics are actively studied for nanostructures such as carbon nanotubes, needle-shaped silicon carbide nanorods, tungsten nanorods, and molybdenum trioxide nanobelts. And the said nanostructure has great interest in the application to the flat panel display of a big screen.
[0003]
In addition, it has been reported that the field emission characteristics of a nanotube are dramatically improved when the tip of the nanotube is open.
[0004]
On the other hand, applications of molybdenum disulfide nanostructures to electrochemical hydrogen adsorption / desorption electrodes, solid lubricants, and the like have been studied (for example, see Non-Patent
[0005]
[Non-Patent Document 1]
J. Chen et al., Journal of American Chemical Society (J. Am. Chem. Soc), 2001, Vol. 123, p. 11813 [Non-patent Document 2]
L. Rapoport et al., Nature, 1997, Vol. 387, p. 791 [0006]
[Problems to be solved by the invention]
The invention of this application has been made in view of the above-described prior art, and solves the problem of providing molybdenum disulfide nanoflowers having excellent field emission characteristics and useful as a field emission material, and a method for producing the same. It should be a challenge.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the invention of this application is characterized in that several thousand petal-like structures having a width of 100 to 200 nanometers and a thickness of several nanometers are assembled. Nanoflowers (Claim 1) are provided.
[0008]
Further, the invention of this application is to manufacture molybdenum disulfide nanoflowers, wherein the molybdenum oxide thin film is heated to 950 to 1000 ° C. in a sulfur vapor atmosphere to produce the molybdenum disulfide nanoflowers according to
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The molybdenum disulfide nanoflowers of the invention of this application and the method for producing the same have the characteristics as described above, but the examples are shown below, and the molybdenum disulfide nanoflowers of the invention of this application and the method for producing the same. This will be described in more detail.
[0010]
【Example】
Sulfur powder was placed in a graphite crucible, and a molybdenum foil (10 mm × 10 mm × 0.1 mm) was placed about 1 cm above the crucible. An infrared irradiation furnace was used with these sulfur powder and molybdenum foil as starting materials, the molybdenum foil was heated to 950 to 1000 ° C., and the sulfur powder was heated to 300 to 350 ° C. for 20 minutes. A thin layer on the surface of molybdenum oxide formed by oxidizing the molybdenum foil was reduced by the generated sulfur vapor.
[0011]
As a result of examining the product by X-ray diffraction, it was confirmed that a hexagonal molybdenum disulfide phase having lattice constants a = 3.16Å and c = 12.3Å was formed. Further, as a result of observing the product with a scanning electron microscope, the product had a flower shape as shown in FIGS. 1 (a) and 1 (b), and the size was several hundred nanometers. . This nanoflower was composed of thousands of petals, and the size of one petal was about 100 to 200 nanometers in width and several nanometers in thickness.
[0012]
A small amount of nanoflowers were peeled off from the molybdenum foil to which the above nanoflowers were attached, dispersed in alcohol, and subjected to ultrasonic treatment for 15 minutes. The dispersion was then dropped onto a copper grid with a carbon film and dried. The crystal structure and chemical composition of nanoflowers were analyzed using a high-resolution transmission electron microscope with an X-ray energy diffusion spectrometer and an electron energy loss spectrometer. Nanoflowers were stable without being destroyed in shape even during ultrasonic treatment.
[0013]
As shown in FIG. 2, the measurement result of the electron energy loss spectrum revealed that the chemical composition of the nanoflower is composed of molybdenum (227 eV) and sulfur atom (165 eV). The result of electron beam diffraction confirmed that it was a pure hexagonal molybdenum disulfide phase.
[0014]
FIG. 3 is a high-resolution transmission electron microscope image of a typical nanoflower, and the stripe pattern on the bottom surface of the (002) crystal of hexagonal molybdenum disulfide is clearly observed. The number of layers composing the petals decreased toward the tip, with less than 5 layers at the tip and a thickness of about 1-3 nanometers.
[0015]
The field emission characteristics were measured in a vacuum of 2.0 × 10 −7 Torr using a rod-shaped aluminum probe having a cross-sectional area of 1 mm 2 as an anode and molybdenum disulfide nanoflowers as a cathode. FIG. 4 shows the results of measuring the current density when a voltage of 0 to 1100 V was applied and the distance between the anode and the nanoflower was changed from 100 to 150 μm.
[0016]
When the voltage required to generate a current density of 10 μA / cm 2 and 10 mA / cm 2 is defined as a start voltage and a threshold voltage, respectively, molybdenum disulfide nanoflowers have a start voltage of 4.5 to 5.5 V / μm and a threshold voltage of It was found to be 7.6 to 8.6 V / μm. Thus, the reason why the molybdenum disulfide nanoflowers exhibit excellent field emission characteristics is that the tips of the petals are very thin and open.
[0017]
Of course, the invention of this application is not limited by the above embodiments. Needless to say, various details are possible.
[0018]
【The invention's effect】
As described in detail above, the invention of this application provides molybdenum disulfide nanoflowers having excellent field emission characteristics and useful as a field emission material, and a production method for realizing the same.
[Brief description of the drawings]
FIGS. 1A and 1B are scanning electron microscopic images of molybdenum disulfide nanoflowers obtained in Examples, respectively.
FIG. 2 is an electron energy loss spectrum of molybdenum disulfide nanoflowers obtained in the examples.
FIG. 3 is a high-resolution transmission electron microscope image of molybdenum disulfide nanoflowers obtained in the examples.
FIG. 4 is a graph showing field emission characteristics (relationship between voltage and current density) of molybdenum disulfide nanoflowers obtained in Examples.
Claims (2)
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP6175596B2 (en) * | 2014-01-31 | 2017-08-02 | 博 久保田 | Method for producing hydrogen production catalyst |
| CN103924213A (en) * | 2014-04-29 | 2014-07-16 | 清华大学 | Method for preparing molybdenum disulfide film for field emission device |
| CN105366725B (en) * | 2014-08-29 | 2017-02-15 | 中国科学院大连化学物理研究所 | Method for hydro-thermally synthesizing MoS2 nanoflower with sulfur-containing biological reagent as sulfur source |
| CN106830082B (en) * | 2017-01-10 | 2019-03-01 | 四川大学 | A kind of method that controllable magnanimity prepares molybdenum disulfide nano band |
| JP6614471B1 (en) | 2018-03-19 | 2019-12-04 | Dic株式会社 | Molybdenum sulfide, production method thereof, and hydrogen generation catalyst |
| CN109745929B (en) * | 2019-03-13 | 2021-06-08 | 江南大学 | Preparation method of molybdenum oxide/molybdenum disulfide core-shell microspheres |
| WO2021059325A1 (en) | 2019-09-24 | 2021-04-01 | Dic株式会社 | Molybdenum sulfide powder and method for producing same |
| EP4292985A1 (en) | 2021-02-09 | 2023-12-20 | Dic Corporation | Metal-doped molybdenum sulfide powder and production method therefor |
| CN114768530B (en) * | 2022-04-29 | 2023-03-28 | 中国工程物理研究院材料研究所 | Application of molybdenum disulfide in hydrogen isotope electrolytic separation |
| CN114854387B (en) * | 2022-05-24 | 2023-02-03 | 中国石油大学(北京) | Nano flower-nano sheet dual-inorganic nano profile control and flooding system and application thereof |
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