Solution phase synthesis of Na0.28V2O5 nanobelts into nanorings and the electrochemical performance in Li battery

In this paper, we are the first to report a simple one step hydrothermal method to synthesize Na0.28V2O5 nanorings/nanobelts without using any organic surfactant/solvents at 130-160 degrees C for 1-2 days. The obtained products have been characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, morphology by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and electrochemical discharge-charge test for lithium battery. XRD pattern exhibit a monoclinic Na0.28V2O5 structure. FTIR spectrum shows band at 958 cm(-1) is assigned to V=O stretching vibration, which is sensitive to intercalation and suggests that Na+ ions are inserted between the vanadium oxide layers. TEM analyses reveal that the products consist of nanorings of width about 500 nm and thickness of about 100 nm with inner diameter of 5-7 mu m. Nanobelts of width 70-100 nm and several tens of micrometers in length are observed. The electrochemical results show that nanorings/nanobelts exhibit an initial discharge capacity of 320 mAh g(-1) and its capacity still retained 175 mAh g(-1) even after 69 cycles. We have discussed the possible growth mechanism for the formation of nanorings/nanobelts. (c) 2012 Elsevier Ltd. All rights reserved

Simple non-basic solution route for the preparation of zinc oxide hollow spheres

Despite considerable efforts undertaken in a rapidly developing area of materials research, controlled synthesis of nanostructured ZnO is still a matter of intensive research. Herein, we report a facile base free approach for the fabrication of nanostructured ZnO hollow spheres. In the synthesis, ethylene glycol has been introduced as solvent and crystal-growth modifier and zinc acetate has been used as zinc precursor and also a source of soft template. ZnO nanoparticles of diameter â¼25 nm are assembled into highly regular hollow spheres. The powder X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL) and UV-visible spectroscopy have been used to characterize the crystal structure, morphology, composition and optical properties. Powder XRD pattern of ZnO confirms the formation of the wurtzite structure. Presence of oxygen deficiency in the prepared ZnO product is revealed by Raman and EDS studies. Strong emission at 422 nm with three weak emissions at 400, 484 and 529 nm were observed by PL spectrum. The growth mechanism for the formation of ZnO hollow spheres has been discussed on the basis of the growth model for the polar ZnO crystals. © 2012 Elsevier B.V

Synthesis of single crystalline (NH4)2V6O16·1.5H2O nest-like structures

Novel nest-like (NH4)2V6O16·1.5H2O structures made of nanobelts have been synthesized by a facile hydrothermal approach. The powder X-ray diffraction pattern of the sample reveals the monoclinic crystalline phase of (NH4)2V6O16·1.5H2O. The scanning electron microscopy images of the sample obtained at 130 °C for 3 days exhibit nest-like morphology. The transmission electron microscopy result reveals that the nanobelts have a smooth surface. The selected area electron diffraction pattern of the nanobelts indicates single crystalline nature. The two major weight losses occur in thermogravimetric analysis which correspond to the removal of water and ammonia molecules. Further, calcination of the (NH4)2V6O16·1.5H2O product results in the formation of orthorhombic phase of shcherbianite V2O5

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

ZnO nanowires, nanorods and microrods have been prepared by an organic-free hydrothermal process using ZnSO4 and NaOH/NH4OH 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-1 associated with the characteristic vibrational mode of Zn-O bonding. The thickness 75-300 nm for ZnO nanorods and 0.2-1.8 μm 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 organic-free hydrothermal synthesis of the ZnO nano/microrods is discussed. © 2010 Elsevier Ltd. All rights reserved

Flowering and fruit set in vanilla (Vanilla planifolia Andr.)

Cultivation of vanilla (Vanilla planifolia Andr.) is becoming increasingly popular in recent years in the hill zone of Karnataka, India. &nbsp

Comparison of the photocatalytic degradation of trypan blue by undoped and silver-doped zinc oxide nanoparticles

Zinc oxide (ZnO) and silver doped zinc oxide (ZnO:Ag) nanoparticles were prepared using nitrates of zinc and silver as oxidizers and ethylene diaminetetraacetic acid (EDTA) as a fuel via low-temperature combustion synthesis (LCS) at 500 degrees C. X-ray diffraction (XRD) pattern indicates the presence of silver in the hexagonal wurtzite structure of ZnO. Fourier transform infrared (FTIR) spectrum indicates the presence of Ag-Zn-O stretching vibration at 510 cm(-1). Transmission electron microscopy (TEM) images shows that the average particle size of ZnO and ZnO:Ag nanoparticles were found to be 58 nm and 52 nm, respectively. X-ray photoelectron spectroscopy (XPS) data clearly indicates the presence of Ag in ZnO crystal lattice. The above characterization techniques indicate that the incorporation of silver affects the structural and optical properties of ZnO nanoparticles. ZnO:Ag nanoparticles exhibited 3% higher photocatalytic efficiency than pure ZnO nanoparticles. ZnO:Ag nanoparticles show better photocatalytic activity for the degradation of trypan blue (TrB) compared to undoped ZnO nanoparticles. (C) 2014 Elsevier Ltd. All rights reserved