Surfactant free hydrothermally derived ZnO nanowires, nanorods, microrods and their characterization

Abstract

a b s t r a c tZnO nanowires, nanorods and microrods have been prepared by an organic-free hydrothermal process using ZnSO 4 and NaOH/NH 4 OH solutions. The powder X-ray diffraction (PXRD) patterns reveal that the ZnO nano/microrods are of hexagonal wurtzite structure. The Fourier transform infrared (FT-IR) spectrum of ZnO powder shows only one significant spectroscopic band at around 417 cm À 1 associated with the characteristic vibrational mode of Zn-O bonding. The thickness 75-300 nm for ZnO nanorods and 0.2-1.8 mm for microrods are identified from SEM/TEM images.UV-visible absorption spectra of ZnO nano/microrods show the blue shift. The UV band and green emission observed in photoluminescence (PL) spectra are due to free exciton emission and singly ionized oxygen vacancy in ZnO. Finally, the mechanism for organicfree hydrothermal synthesis of the ZnO nano/microrods is discussed.

Recovery of Zn from wastewater of zinc plating industry by precipitation of doped ZnO nanoparticles

“…In accordance with the X-ray data, the precipitates consist mainly of ZnO. Sample 40_9_4 shows an intensive absorbance band at 417 cm -1 attributed to the characteristic vibrational mode of Zn-O bonding (Nagaraju et al 2010) and a much weaker band at 580 cm -1 . Additional very weak bands at 713, 872, 1135, 1400 and 1498 cm -1 correspond to a very small amount of low crystalline ZnCO 3 (smithsonite), and very weak bands at 445, 470, 1626, 3200 and 3400 cm -1 are assigned to traces of Zn(OH) 2 .…”

Blue-shifted and picosecond amplified UV emission from aqueous chemical grown ZnO microrods

“…The shift may be due to the relative contributions of the excitonic recombination and its longitudinal optical (LO) phonon replicas and/or to the thermal effects caused by laser heating [26][27][28]. In contrast with ZnO micro/nanostructures similarly fabricated by ACG method [4][5][6][7][8][9][10][11]14,15] and to those prepared by different techniques [29][30][31], the microrods do not exhibit any visible defect-related emissions. This result implies that the as-prepared ZnO microrod samples are of good optical quality.…”

“…7(b)) is made up of tetrahedrally coordinated zinc (Zn 2+ ) and oxygen (O 2À ) ions stacked alternately along the c-axis. The Zn-terminated and O-terminated sides produce net positively-charged and negatively-charged surfaces, respectively [11]. With the dissociative nature of the ACG method and the polarity of the ZnO crystal structure, the ZnO microrods would then follow a typical hexagonal crystal habit (Fig.…”

“…Among the techniques used, the aqueous chemical growth (ACG) method (often referred to as hydrothermal method or solution route) is a low cost, simple, and effective way to fabricate hexagonal and crystalline ZnO micro/nanostructures. Using tabletop equipment and few chemical precursors, ZnO rods [3][4][5][6][7][8][9], flowers or multipods [10][11][12], stars [13], prisms [14], and nanoparticles [15] are produced with high yield at relatively low temperatures. ZnO microrods prepared by ACG, for example, can be isolated and can be used for device fabrication [16].…”

Effect of growth conditions on zinc oxide nanowire array synthesized on Si (100) without catalyst

“…ZnO nanostructures can be grown in a wide variety of morphologies such as nanowires, nanorods, nanotetrapods, nanobelts, nanorings, and nanocombs [10][11][12][13][14][15][16]. Among them nanowires and nanorods grown by vapor deposition techniques as well as solution based methods have attracted much attention because they provide a direct path for charge transport [17] and have high surface to volume ratio (high surface area).…”