Formation of Crystalline Na2V6O16·3H2O Ribbons into Belts and Rings

Single-​cryst. nanobelts and nanorings of Na2V6O16·3H2O structures have been facilely synthesized through a direct hydrothermal reaction between NaVO3 and H3PO4, without the addn. of any harmful solvents or surfactants. The anal. techniques of SEM, transmission electron microscopy (TEM)​, powder X-​ray diffraction, TGA, energy-​dispersive X-​ray spectroscopy, FTIR spectroscopy, high-​resoln. TEM, and selected-​area electron diffraction have been used to characterize the morphol., compn., and structure of the synthesized products. The Na2V6O16·3H2O nanobelts are up to several hundreds of micrometers in length and 100-​300 nm in thickness, and for nanorings, the diams. are 4.5-​6.5 μm. H3PO4 plays a key role in maintaining the pH of the soln. as well as producing PO43-​ ions in soln. The chem. reactions and a possible growth mechanism involved in the formation of Na2V6O16·3H2O nanobelts and nanorings are briefly discussed

Nanostructural zinc oxide hollow spheres: A facile synthesis and catalytic properties

The development of reproducible procedures for the synthesis and organization of nanostructured metal oxides is important in order to exploit the unique properties of these materials for practical applications. The present work describes the transformation of Zn(NH3)4] 2+ into hollow structured ZnO materials through solvothermal decomposition. An increase in ammonia concentration in the reaction medium, significantly changes the morphology of ZnO from spheres made of nanoparticles (20-30 nm) to hollow spheres composed of nanorods (200-350 nm) or to free microrods as evidenced from scanning and transmission electron micrographs (SEM/TEM). The powder X-ray diffraction (XRD) pattern of ZnO confirms formation of the wurtzite structure. Raman and Energy-dispersive spectroscopic (EDS) studies indicate the presence of oxygen deficiency in ZnO. The investigation on the catalytic behavior of ZnO in the synthesis of (4-methoxyphenyl)(phenyl) methanone (MPPM) by Friedel-Crafts acylation of anisole with benzoyl chloride has also been carried out. The results reveal that the prepared ZnO could produce �98 of yield compared to 41 produced by commercial ZnO. © 2010 Elsevier B.V. All rights reserved

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

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

Morphological Evolution of (NH4)(0.5)V2O5 center dot mH(2)O Fibers into Belts, Triangles, and Rings

In this contribution, single-crystalline (NH4)(0.5)V2O5 center dot mH(2)O xerogels made of belts, rings, triangles, and ovals have been synthesized using a surfactant-free hydrothermal method. The analytical techniques of scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR), high-resolution TEM (HRTEM), and selected area electron diffraction (SAED) have been used to characterize the morphology, composition, and structure of the as-prepared products. On the basis of SEM and TEM observations, we suggested that the as-prepared (NH4)(0.5)V2O5 center dot mH(2)O rings, triangles, and ovals have been formed by connecting two ends of the vanadium oxide sheet made of edge and corner sharing VO5 square pyramids. The as-prepared (NH4)(0.5)V2O5 center dot mH(2)O nanobelts are up to several hundreds of micrometers long, 402-551 nm wide, and 235-305 nm thick. The thickness and width of the rings are respectively similar to 454 nm and similar to 1 mu m. Triangles with three unequal sides having a thickness of similar to 143 nm and a width of similar to 1 mu m were also formed. The crystalline orthorhombic phase of shcherbianite V2O5 was obtained on calcination of (NH4)(0.5)V2O5 center dot mH(2)O at 350 degrees C for 2 h. The SEM image of this V2O5 product retains the parent morphology of the preheated compound. A possible reaction mechanism and the growth process involved in the formation of belts/rings/triangles and ovallike microstructures are discussed

Studies on the synthesis of CdCO3 nanowires and porous CdO powder

In the present study, we demonstrate the self transformation of aqueous cadmium acetate into CdCO3 nanowires through hydrothermal reaction. The reaction temperature and the volume ratio of water to ethanol were found to be crucial for the formation of CdCO3 nanowires. The nanowires are of single crystal in nature having width ⼠17-30 nm as observed from selected area electron diffraction (SAED) pattern and transmission electron microscopic (TEM) results. The major weight loss found in thermogravimetric analysis (TGA) corresponds to the formation of CdO and CO2. The powder X-ray diffraction (PXRD) patterns of CdCO3 and CdO are respectively indexed to pure rhombohedral and cubic phases. The photoluminescence (PL) spectrum of CdO exhibits an emission peak at 483 nm due to the transition between the valence and conduction bands. © 2009 Elsevier B.V. All rights reserved

Vanadium pentoxide nanobelts: One pot synthesis and its lithium storage behavior

In this paper, we report a synthesis, characterization and electrochemical properties of V 2O 5 nanobelts. V 2O 5 nanobelts have been prepared via hydrothermal treatment of commercial V 2O 5 in acidic (HCl/H 2SO 4) medium at relatively low temperature (160 °C). The hydrothermally derived products have been characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photo electron spectroscopy (XPS), UV-Vis spectroscopy, Scanning/Transmission electron microscopy (SEM/TEM). XRD pattern of V 2O 5 nanobelts show an orthorhombic phase. From the FTIR spectrum, the peak observed at 1018 cm -1 is characteristic of the stretching vibration mode of the terminal vanadyl, V = O. The UV-Vis absorption spectrum of V 2O 5 nanobelts show maximum absorbance at 430 nm, which was blue-shifted compared to that of bulk V 2O 5. TEM micrographs reveal that the products consist of nanobelts of 40-200 nm in thickness and several tens of micrometers in length. The electrochemical analysis shows an initial discharge capacity of 360 mAh g -1 and its almost stabilized capacity is reached to 250 mAh g -1 after 55 cycles. A probable reaction mechanism for the formation of orthorhombic V 2O 5 nanobelts is proposed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

An efficient and a novel route for the synthesis of titania via solution combustion of peroxotitanic acid

Despite considerable efforts undertaken in a rapidly developing area of materials research, synthesis of TiO2 nano-powder via green methodologies has a great scientific importance. Here, we present a novel green approach for the synthesis of TiO2 nano-powder by solution combustion process using titanium peroxo complex and tartaric acid (TA) as an intial precursor. The water-soluble peroxo–α-hydroxy–carboxylato titanium complex, an intermediate precursor mass at external temperature of 500 °C, resulted in the oxide of pure anatase phase. This green process involves universal green solvent hydrogen peroxide and it minimizes the time, energy and cost of the production of TiO2