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Abstract: In this paper we present a systematic study on the morphological variation of ZnO nanostructure by varying the pH of precursor solution via solution method. Zinc acetate dihydrate and sodium hydroxide were used as a precursor, which was refluxed at 90°C for an hour. The pH of the precursor solution (zinc acetate di hydrate) was increased from 6 to 12 by the controlled addition of sodium hydroxide (NaOH). Morphology of ZnO nanorods markedly varies from sheet-like (at pH 6) to rod-like structure of zinc oxide (pH 10–12). Diffraction patterns match well with standard ZnO at all pH values. Crystallinity and nanostructures were confirmed by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) pattern, which indicates structure grew along [0001] direction with an ideal lattice fringes distance 0.52nm. FTIR spectroscopic measurement showed a standard peak of zinc oxide at 464cm−1. Amount of H+ and OH− ions are found key to the structure control of studied material, as discussed in the growth mechanism. [Copyright &y& Elsevier]

Abstract: Rosette-like structures of ZnO were synthesized at low temperature (60°C) using solution process over 20min of time. Hydroxylamine hydrochloride was used as capping agent with zinc nitrate hexahydrate and sodium hydroxide. Transition from triangular shaped plate like particles to rosette-like structure and to individual nanorods is observed with increasing refluxing temperature. Single-crystalline nature with wurtzite hexagonal phase is confirmed from transmission electron microscopic observations. Photoelectron spectroscopic measurement presented spectra close to the standard bulk ZnO, with an O 1s peak composed of surface adsorbed O–H group, O2− in the oxygen vacancies on ZnO structure and ZnO. [Copyright &y& Elsevier]

Abstract: Faceted nanoparticles of zinc oxide were successfully achieved via thermal annealing of hydrozincite (Zn5(CO3)2(OH)6) powder at different annealing temperatures, i.e. 300, 500 700 and 900°C in air for 2h using sol–gel method by refluxing for 6h at 70°C. Zinc acetate dihydrate (Zn(CH3COO)2·2H2O) was used as precursor with urea (NH2CONH2) for the synthesis of hydrozincite. The morphological observations by field emission scanning electron microscope indicated increase in particle size from 20 to 300nm with increase in the annealing temperatures. High resolution TEM and SAED measurement indicate the distance between two lattice fringes is ∼0.52nm corresponding to (0001) fringes. A standard peak of zinc oxide was observed at 457cm−1 from the FTIR analysis. Thermo gravimetric analysis (TGA) revealed that the primary weight loss starts at ∼130°C due to solvent evaporation and the secondary weight loss due to phase transition from hydrated zinc oxide to zinc oxide was observed at ∼290°C. [Copyright &y& Elsevier]

Abstract: Effect of the structure-directing agent on the floral (depicting flower) morphological variation of ZnO is systematically studied and presented here. Flowery decorated (resembling flower) zinc oxide structure composed of hexagonal nanorods (sharp tips and wider bases) was synthesized at 90°C using zinc acetate dihydrate and sodium hydroxide at various concentrations of hydroxylamine hydrochloride for 12h by solution method. Single crystalline nature with the wurtzite hexagonal phase remained unaltered with increasing concentration of hydroxylamine hydrochloride while the morphology changes from nanorod to plate like structure. Photoelectron spectroscopic measurement presented spectra close to the standard bulk ZnO, with an O 1s peak composed of surface adsorbed OO2− in the oxygen vacancies on ZnO structure and ZnO. At higher concentration (0.8M), surface adsorbed Oncreases while other component decreases because of the changes in the nucleation and surface energy. Results clearly indicate that hydroxylamine hydrochloride works as a structure-directing agent without affecting other properties. [Copyright &y& Elsevier]

Abstract: Single crystalline needle-shaped zinc oxide nanorods were synthesized via sonochemical methods using zinc acetate dihydrate and sodium hydroxide at room temperature. Morphological investigation revealed that the nanoneedles are of hexagonal surfaces along the length. The typical diameter and length vary from 120 to 160nm and 3 to 5μm, respectively. Sonication time appears to be a critical parameter for the shape determination. Detailed structural characterization confirmed that the nanorods are single crystalline with wurtzite hexagonal phase. A standard peak of zinc oxide was observed at 520cm−1 from the Fourier transform infrared spectroscopy. The ultra-violet visible and room temperature photoluminescence (PL) spectroscopic results demonstrate that the synthesized material has good optical properties. [Copyright &y& Elsevier]

Abstract: Hydrothermal growth of hexagonal ZnO nanorods on the annealed titanate nanotube films is reported as a function of molar ratio of Zn(NO3)2 and methenamine (1:1–1:4). The molar ratio of 1:4 results in a dense and thinner rod in comparison with other molar ratios. Corn-like structures of the rods are believed to be due to the higher amine concentration. Raman peaks at 437 and 331cm−1 are assigned to E2 and E2H–E2L modes. Near band gap edge and green photoluminescence emission indicates the structural and oxygen vacancy. O 1s peak is found built-up of sub-peaks at 530.62, 531.8 and 532.84eV corresponding to O2− on normal wurtzite structure and OH and oxygen vacancies of ZnO, respectively. [Copyright &y& Elsevier]

Abstract: A p–n heterostructure diode of polyaniline (PANI) and ZnO nanoparticles was prepared by the electrophoretic deposition of PANI on ZnO nanoparticles thin film coated fluorine doped tin oxide (FTO) glass at room temperature. The morphological, structural and optical studies substantiated the penetration, bonding and the interaction of PANI molecules with ZnO nanoparticles thin film substrates. The prominent blue shift in UV-Vis spectra indicated the strong interaction between ZnO and PANI through the decreased degree of orbital overlap between electrons of the phenyl rings with the lone pair of the nitrogen atom in the PANI molecules. The characteristics of PANI/ZnO heterostructure diode showed weak rectifying behavior with non-linear nature of curve of PANI/ZnO heterostructure device. The typical ohmic behavior was observed by the characterization of PANI/ZnO heterostructure at the interface of PANI and ZnO thin film layer without top Pt thin layer contact. [Copyright &y& Elsevier]