Continuous hydrothermal synthesis and crystallization of magnetic oxide nanoparticles

2002 ◽  
Vol 17 (9) ◽  
pp. 2410-2416 ◽  
Author(s):  
Linda J. Cote ◽  
Amyn S. Teja ◽  
Angus P. Wilkinson ◽  
Z. John Zhang
Keyword(s):  
Hydrothermal Synthesis ◽  
Elevated Temperatures ◽  
Metal Salt ◽  
Oxide Nanoparticles ◽  
Precipitation Reaction ◽  
Ambient Conditions ◽  
Magnetic Oxide ◽  
Synthesis Of Nanoparticles ◽  
Uniform Particles ◽  
Metal Salt Solution

The continuous hydrothermal synthesis of nanoparticles of two metal oxides (α–Fe2O3 and Co3O4) is described. Two variations of the technique were investigated, involving the precipitation reaction between a metal salt solution and a hydroxide solution at ambient conditions and at elevated temperatures. Elevated temperatures resulted in more uniform particles of α–Fe2O3 and Co3O4, although the actual sizes of the particles were apparently unaffected by the temperature. This behavior was attributed to the species present in solution and the solubilities of the cation(s), both of which were calculated via a thermodynamic model for the systems under study.

scholarly journals Correction: An anionic and cationic surfactant-assisted hydrothermal synthesis of cobalt oxide nanoparticles as the active electrode material for supercapacitors

2021 ◽  
Author(s):  
R. R. Samal ◽  
Aneeya K. Samantara ◽  
S. Mahalik ◽  
J. N. Behera ◽  
B. Dash ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Cobalt Oxide ◽  
Cationic Surfactant ◽  
Electrode Material ◽  
Oxide Nanoparticles ◽  
Active Electrode ◽  
Cobalt Oxide Nanoparticles ◽  
Surfactant Assisted

Correction for ‘An anionic and cationic surfactant-assisted hydrothermal synthesis of cobalt oxide nanoparticles as the active electrode material for supercapacitors’ by R. R. Samal et al., New J. Chem., 2021, 45, 2795–2803; DOI: 10.1039/D0NJ05088A.

scholarly journals Recent advances in the electrochemical construction of heterocycles

2014 ◽  
Vol 10 ◽  
pp. 2858-2873 ◽  
Author(s):  
Robert Francke
Keyword(s):  
Heterocyclic Compounds ◽  
Elevated Temperatures ◽  
Ring Formation ◽  
Environmentally Benign ◽  
Heterocyclic Chemistry ◽  
Ambient Conditions ◽  
Recent Developments ◽  
Strong Acids ◽  
Selection Of ◽  
Made In

Due to the fact that the major portion of pharmaceuticals and agrochemicals contains heterocyclic units and since the overall number of commercially used heterocyclic compounds is steadily growing, heterocyclic chemistry remains in the focus of the synthetic community. Enormous efforts have been made in the last decades in order to render the production of such compounds more selective and efficient. However, most of the conventional methods for the construction of heterocyclic cores still involve the use of strong acids or bases, the operation at elevated temperatures and/or the use of expensive catalysts and reagents. In this regard, electrosynthesis can provide a milder and more environmentally benign alternative. In fact, numerous examples for the electrochemical construction of heterocycles have been reported in recent years. These cases demonstrate that ring formation can be achieved efficiently under ambient conditions without the use of additional reagents. In order to account for the recent developments in this field, a selection of representative reactions is presented and discussed in this review.

An anionic and cationic surfactant-assisted hydrothermal synthesis of cobalt oxide nanoparticles as the active electrode material for supercapacitors

2021 ◽  
Vol 45 (5) ◽  
pp. 2795-2803
Author(s):  
R. R. Samal ◽  
Aneeya K. Samantara ◽  
S. Mahalik ◽  
J. N. Behera ◽  
B. Dash ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Cobalt Oxide ◽  
Cationic Surfactant ◽  
Electrode Material ◽  
Cobalt Hydroxide ◽  
Oxide Nanoparticles ◽  
Active Electrode ◽  
Schematic Representation ◽  
Cobalt Oxide Nanoparticles ◽  
Surfactant Assisted

Schematic representation of surfactant action for synthesis of cobalt hydroxide and oxide.

scholarly journals Preparation and Characterization of Some Nanometal Oxides Using Microwave Technique and Their Application to Cotton Fabrics

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
M. Gouda ◽  
A. Aljaafari ◽  
Y. Al-Fayz ◽  
W. E. Boraie
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Cotton Fabric ◽  
Metal Salt ◽  
Metal Oxide Nanoparticles ◽  
High Energy ◽  
Cotton Fabrics ◽  
Oxide Nanoparticles ◽  
Limiting Oxygen Index ◽  
Cobalt Oxide Nanoparticles

The objective of this paper is the synthesis of some nanometal oxides via microwave irradiation technique and their application to augment multifunctional properties of cotton fabric. Cotton fabrics containing nanometal oxides were prepared via a thiol-modification of cotton fabric samples and then dipped into the metal salt solutions precursors and transferred to the microwave oven. The surface morphology and quantitative analysis of the obtained modified cotton fabrics containing nanometal oxides were studied by scanning electron microscopy coupled with high energy dispersive X-ray (SEM-EDX). The shape and distribution of nanometal oxide inside the fabric samples were analyzed by transmission electron microscopy of cross-section fabric samples. The iron oxide nanoparticles had a nanosphere with particle size diameter 15–20 nm, copper oxide nanoparticles had a nanosphere with particle size diameter 25–30 nm, and cobalt oxide nanoparticles had a nanotube-like shape with a length of 100–150 nanometer and a diameter of ~58 nanometer, whereas the manganese oxide nanoparticles had a linear structure forming nanorods with a diameter of 50–55 nanometer and a length of 70–80 nanometers. Antibacterial activity was evaluated quantitatively against gram-positive bacteria such asStaphylococcus aureusand gram-negative bacteria such asEscherichia coli, UV-protection activity was analyzed using UV-DRS spectroscopy, and flame retardation of prepared fabric samples was evaluated according to the limiting oxygen index (LOI). Results revealed that the prepared fabric sample containing nanometal oxide possesses improved antibacterial, LOI, and UV-absorbing efficiency. Moreover, the metal oxide nanoparticles did not leach out the fabrics by washing even after 30 laundering washing cycles.

scholarly journals Mixed Metal-Antimony Oxide Nanocomposites: Low pH Water Oxidation Electrocatalysts with Outstanding Durability at Ambient and Elevated Temperatures

2021 ◽  
Author(s):  
Luke Sibimol ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany Kerr ◽  
Jiban Kangsabanik ◽  
...  
Keyword(s):  
Water Oxidation ◽  
High Performance ◽  
Density Functional ◽  
High Stability ◽  
Proton Exchange Membrane ◽  
Elevated Temperatures ◽  
Antimony Oxide ◽  
Proton Exchange ◽  
Efficient Production ◽  
Ambient Conditions

Proton-exchange membrane water electrolysers provide many advantages for the energy-efficient production of H<sub>2</sub>, but the current technology relies on high loadings of expensive iridium at the anodes, which are often unstable in operation. To address this, the present work scrutinises the properties of antimony-metal (Co, Mn, Ni, Fe, Ru) oxides synthesised as flat thin films by a solution-based method for the oxygen evolution reaction in 0.5 M H<sub>2</sub>SO<sub>4</sub>. Among the non-noble-metal catalysts, only cobalt-antimony and manganese-antimony oxides demonstrate high stability and reasonable activity under ambient conditions, but slowly lose activity at elevated temperatures. The ruthenium-antimony system is highly active, requiring an overpotential of 0.39 ± 0.03 and 0.34 ± 0.01 V to achieve 10 mA cm<sup>-2</sup> at 24 ± 2 and 80 °C, respectively, and remaining remarkably stable during one-week tests at 80 °C. The <i>S</i>-number for this catalyst is higher than that for the high-performance benchmark Ir-based systems. Density functional theory analysis and physical characterisation reveal that this high stability is supported by the enhanced hybridisation of the oxygen p- and metal d-orbitals induced by antimony, and can arise from two distinct structural scenarios: either formation of an antimonate phase, or nanoscale intermixing of metal and antimony oxide crystallites.

The Vibrational Spectra of NH4VO3 at Elevated Temperatures and Pressures

1987 ◽  
Vol 42 (7) ◽  
pp. 843-852 ◽  
Author(s):  
A . M. Heyns ◽  
M. W. Venter ◽  
K.-J. Range
Keyword(s):  
Hydrogen Bonds ◽  
Temperature Dependence ◽  
Vibrational Spectra ◽  
Elevated Temperatures ◽  
Structural Data ◽  
Volume Effect ◽  
Ambient Conditions ◽  
Hydrogen Bond Interactions ◽  
Diamond Anvil ◽  
Pressure Changes

Abstract Results obtained from the vibrational spectra of NH4VO3 and its deuterated analogues show that at least two types of hydrogen bond interactions can be identified at am bient conditions. In accordance with the structural data on NH4VO3 (F. C. Hawthorne and C. Calvo, J. Solid State Chem. 22, 157 (1977)) these interactions are assigned to normal, strong hydrogen bonds and weaker bifurcated ones, respectively. The temperature dependence of some of the N -H bands indicates that the normal hydrogen bonds decrease in strength with increasing temperatures, while the bifurcated ones tend to increase in strength. The NH4+ ions do not show fluxional behaviour at ambient conditions and even the bifurcated hydrogen bonds are of the type that is dominated by acceptor strength of the anions and not by a volume effect. The Ram an active NH4+ vibrations are very weak compared to the V - O modes and could not all be observed in the highpressure diamond anvil cell. The temperature dependence of the V - O Ram an active modes suggests that changes in the crystals of NH4VO3 brought about by the application of heat mainly involve the O -V -O angles, while pressure changes are mostly accommodated by changes in the V -O bridging bonds and O -V -O bridging angles.

Supercritical Hydrothermal Synthesis of Nanoparticles

2004 ◽  
Vol 2004 (0) ◽  
pp. 225-230
Author(s):  
Seiichi TAKAMI ◽  
Satoshi OHARA ◽  
Mitsuo UMETSU ◽  
Takao TSUKADA ◽  
Tadafumi ADSCHIRI
Keyword(s):  
Hydrothermal Synthesis ◽  
Synthesis Of Nanoparticles ◽  
Supercritical Hydrothermal Synthesis

scholarly journals Recent Advances in the Synthesis and Stabilization of Nickel and Nickel Oxide Nanoparticles: A Green Adeptness

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Muhammad Imran Din ◽  
Aneela Rani
Keyword(s):  
Nickel Oxide ◽  
Green Synthesis ◽  
Biological Effects ◽  
Cost Effective ◽  
Synthetic Methods ◽  
Biological Behavior ◽  
Oxide Nanoparticles ◽  
Nickel Oxide Nanoparticles ◽  
Synthesis Of Nanoparticles ◽  
Synthesis Properties

Green protocols for the synthesis of nanoparticles have been attracting a lot of attention because they are eco-friendly, rapid, and cost-effective. Nickel and nickel oxide nanoparticles have been synthesized by green routes and characterized for impact of green chemistry on the properties and biological effects of nanoparticles in the last five years. Green synthesis, properties, and applications of nickel and nickel oxide nanoparticles have been reported in the literature. This review summarizes the synthesis of nickel and nickel oxide nanoparticles using different biological systems. This review also provides comparative overview of influence of chemical synthesis and green synthesis on structural properties of nickel and nickel oxide nanoparticles and their biological behavior. It concludes that green methods for synthesis of nickel and nickel oxide nanoparticles are better than chemical synthetic methods.

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