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Catechol-assisted Hydrothermal Synthesis of ZnO Micro/Nanostructures

Author: SunJie
Tutor: ShaoChangLu
School: Northeast Normal University
Course: Materials Physics and Chemistry
Keywords: ZnO Hydrothermal Nanostructures Catechol-assisted Photoluminescence
CLC: O614.241
Type: Master's thesis
Year: 2012
Downloads: 21
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Abstract


Over the past decade, the synthesis and functionalization of nanostructures haveattracted great interest due to their significant potential application. Many kinds ofsemiconductor nanowires and nanotubes such as Si, GaN, CdS, Se, etc. have beenprepared. Semiconductor oxide nanomaterials, such as ZnO, Ga2O3, In2O3and SnO2,have been hot subjects because of the wide use as basic materials for transparentconducting films, photoelectronics, and gas sensors. Among them, ZnO is of interestfor low-voltage and short wavelength electrooptical devices such as light emittingdiodes and diode lasers due to its wide band gap （3.2eV） and large exciton bindingenergy of60meV. Many interesting nanostructures of ZnO including nanobelts,nanobridges, nanonails, and nanoribbons have been fabricated by thermal evaporationof oxide powders. However, these methods are very difficult to control the course ofcrystallization. This makes the products to obtain relatively poor size uniformity andlow crystallinity, which to some extent limit their use in many applications. Therefore,increasing attention is being paid to develop effective and facile synthetic strategiesfor the synthesis of ZnO materials with controlled size and morphology, whichstrongly affect their properties.Hydrothermal method, as an important method for wet chemistry, has beenemployed for the preparation of ZnO materials in the last decade, and particles withnarrow size distribution, little or no microagglomeration, well crystallization andphase homogeneity can be obtained. Under the hydrothermal condition, the growthrate and the orientation control is a contradiction: as the concentration of growth unitsincreases, the growth rate will also increase, while the growth orientation tends to beconfused. To achieve high growth rate and good orientation simultaneously is the goalof many materialists. In the present paper, a surfactant assisted hydrothermal methodis found to be able to promote the formation of ZnO crystal and control the orientationof products at the same time. Aatechol, which has been generally used as chelatingagent to synthesize mesoporous materials, is introduced to hydrothermal process tofavor the erosion of zinc and control the morphology of ZnO crystals.In this work, a facile and effective catechol-assisted hydrothermal method had beenemployed to synthesis of ZnO nanostructures with good crystallinity. The morphologyand structure were studied by scanning electron microscopy （SEM）, X-ray diffraction（XRD）, Energy Dispersive X-ray Spectrometry （EDS） and Photoluminescence （PL） analytic technology, respectively. The results showed that the catechol played aimportant role to directing the size and morphology of the as-prepared ZnOnanostructures, because of the formation of Zn-catechol chelates could slow down thegrowth rate of the ZnO nanostructures during the hydrothermal process.

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CLC: > Mathematical sciences and chemical > Chemistry > Inorganic Chemistry > Metal elements and their compounds > Section II group metal element and its compounds > The zinc Vice family (Ⅱ B group metal elements ) > Zinc Zn
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