Various nanostructures such as porous nanorods and hierarchical n

Various nanostructures such as porous nanorods and hierarchical nanostructures consisting of porous nanosheets or crystalline nanorods could be synthesized by add to your list employing ethanol in the oleic-acid-dissolving solvent Inhibitors,Modulators,Libraries mixture instead of n-hexane, by controlling the addition of NaOH, or by mild heating of the solutions. Our main focus was directed at studying the effect of size, crystallinity, surface area, morphology, and nano-porosity of the various nanostructures on the gas response and linearity of the resulting gas sensors.2.?Experimental SectionThe morphologies of Zn-precursors were controlled by changing the reaction steps and reaction temperatures. Three Zn-precursors with different morphologies were prepared: hierarchical structures assembled from nanosheets (referred as ��H-NS�� precursor); thin nanorods (��NR�� precursor); hierarchical structures assembled from thick nanorods (��H-NR�� precursor).
These were converted into the corresponding ZnO nanostructure-like morphologies by heat treatment at 500 ��C for 1 h, and will be referred to hereafter as the ��H-NS��, ��NR�� and ��H-NR�� nanostructures, respectively.2.1. Preparation of H-NS PrecursorsZn(NO3)2?6H2O (2.38 g, Inhibitors,Modulators,Libraries >99%, Kanto Chemical, Japan) was dissolved in deionized water Inhibitors,Modulators,Libraries (160 mL) after which ethanol (C2H5OH, 40 mL, 99%, Sigma Aldrich, USA) and oleic acid (C18H34O2, 1.28 g, >99%, Sigma Aldrich, USA) were added to the solution in sequence with stirring. While ethanol and oleic acid are miscible with each other, oleic acid is insoluble in aqueous solution.
Thus, water-insoluble and ethanol-soluble surfactant (oleic acid) was provided continuously and gradually by the forced stirring of the emulsion mixture of the oleic-acid-dissolved ethanol solution and the dissolved Zn-precursor aqueous solution. After 50% NaOH aqueous solution (6.4 g, Samchun Chemical Inhibitors,Modulators,Libraries Co., Korea) was instantaneously poured into the mixture, the resulting emulsion was stirred for 1 h at room temperature.2.2. Preparation of NR Precursors50% NaOH aqueous solution (6.4 g) was dissolved in deionized water (160 mL). Then Zn(NO3)2?6H2O (2.38 g) dissolved in ethanol (40 mL) and oleic acid (1.28 g) were instantaneously poured into the solution in sequence. The solution was reacted for 1 h with continuous stirring.2.3. Preparation of H-NR PrecursorsZn(NO3)2?6H2O (2.38 g) was dissolved in deionized water (200 mL).
After the instantaneous addition of 50% NaOH solution (9.6 g), the solution was heated at 90 ��C for 1 h. The resultant products were collected by centrifugation, washed several times with deionized water and ethanol, and dried at room temperature.2.4. CharacterizationThe phase and crystallinity of the powders were analyzed by X-ray diffraction Drug_discovery (XRD, Rigaku D/MAX-2500 V/PC). The morphology of the powders was investigated using field-emission scanning electron microscopy (FE-SEM, S-4800, Hitachi Co. Ltd., Japan).

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