Preparation of ZnO Nanowires in a Neutral Aqueous System: Concentration Effect on the Orientation Attachment Process

Abstract

ZnO nanowires with diameters in the range of 10 to 30 nm and lengths of ca. several micrometers are prepared with the use of ZnO nanoparticles as building blocks. The length and diameter of the ZnO nanowires can be controlled by the variation of the concentration of the nanoparticles in the orientation attachment process. A plausible mechanism for the concentration‐controlled orientation attachment process is suggested. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Temperature‐Controlled Synthesis and Photocatalytic Performance of ZnO Nanoplatelets

“…Precursor Synthesis and Characterization: Zn(hfa) 2 ÁTMEDA was synthesized according to a recently described literature procedure [32]. The compound was subsequently purified by vacuum sublimation (90°C, 10 -2 mbar), until its melting point fell in the range 106-108°C (yield for the complete synthesis = 63 %).…”

“…[8,10,18] The oppositely charged ions produce a spontaneous polarization along this direction, [1,2,10] as well as a divergence in surface energies, [24] thereby resulting in an anisotropic growth. This phenomenon was further enhanced by the continuous water supply during the deposition, resulting in a preferential interaction of -OH groups with the positively charged, Zn 2+ -terminated (001) polar ZnO surface, [1,9,14] thus favoring precursor decomposition (see above) and a faster growth along the wurtzite <001> direction.…”

“…In this work, we report for the first time the catalyst-free CVD of ZnO nanoplatelets on Si(100) from Zn(hfa) 2 ÁTMEDA, a second-generation source, whose synthesis was recently proposed by Ni et al [32] Such a precursor possesses a high volatility, and prevents undesired oligomerization phenomena thanks to the complete saturation of the Zn II coordination sphere. [32] To the best of our knowledge, despite the use of various base-stabilized Zn(hfa) 2 in CVD processes having already been reported, [32] the chosen compound has never been adopted, to date, in CVD applications.…”

“…ZnO, an n-type, wide band gap semiconductor (E g = 3.4 eV), [1][2][3][4] is one of the most important functional oxides for its interesting chemico-physical properties, such as large exciton binding energy (60 meV), [5][6][7][8] optical transparency, UV emission and electric conductivity, together with a good stability and low toxicity. [7,[9][10][11] On this basis, zinc oxide is extensively considered for various applications, from optoelectronics to energetics, sensing, and photocatalysis.…”

“…[9,10,14,21,[24][25][26] Up to date, 1D and 2D ZnO-based nanomaterials have been prepared by both liquid-and gas-phase techniques, including solvothermal routes, sol-gel, impregnation, laser-assisted methods, evaporation, pyrolysis, and CVD. [2][3][4][5][6][7][8][9][10][13][14][15][16]18,19,24,[26][27][28][29][30] In spite of the relevant number of studies on these topics, a thorough understanding and control of the basic growth mechanism still remains a significant challenge. [27,28] To this regard, CVD processes have received considerable attention for the synthesis of supported nanosystems with tailored properties, even on large-area substrates.…”