Tran Thai Hoa

Monodisperse Uniform CeO2 Nanoparticles

Ceria nanostructure-based catalysts have attracted much attention in recent years because of their unique physiochemical properties. Herein, we have presented a simple two-phase approach for the synthesis of ceria nanocrystals. Structural and morphological characterization by XRD and TEM showed that the as-synthesized monodisperse CeO2 nanoparticles NPs had cubic fluorite crystal structure with average particle size about 6.75 nm. The effects of hydrothermal temperature, annealing time, and concentration of cerium nitrate on the nanostructures of the products were also investigated and discussed. In addition, the CeO2 nanocrystals proved to be an effective catalyst for the photodegradation of blue methylene under UV illumination.Ceria nanostructure-based catalysts have attracted much attention in recent years because of their unique physiochemical properties. Herein, we have presented a simple two-phase approach for the synthesis of ceria nanocrystals. Structural and morphological characterization by XRD and TEM showed that the as-synthesized monodisperse CeO 2 nanoparticles (NPs) had cubic fluorite crystal structure with average particle size about 6.75 nm. The effects of hydrothermal temperature, annealing time, and concentration of cerium nitrate on the nanostructures of the products were also investigated and discussed. In addition, the CeO 2 nanocrystals proved to be an effective catalyst for the photodegradation of blue methylene under UV illumination.

A novel approach for synthesis of hierarchical mesoporous Nd 2 O 3 nanomaterials

Abstract A novel route to the fabrication of hierarchical mesoporous Nd 2 O 3 nanostructures including nanospheres and nanoporous network was described. Their structure and morphology evolution of the as-synthesized materials were determined by various techniques such as scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier transforminfrared spectra, nitrogen adsorption/desorption isotherm, and a formation mechanism was proposed. The results revealed that the Nd 2 O 3 nanospheres had the diameter of 300 nm, which were composed of small primary nanoparticles (NPs) with the size of 10 nm. The nanoporous structure also formed the NPs of ca . 10 nm which were connected with each other to form a three-dimensional (3D) texture. This simple and mild approach to fabricate hierarchical mesoporous Nd 2 O 3 nanostructures could be easily scaled up and potentially extended to synthesize other oxide hierarchical structures.

Synthesis of Gold Nanoparticles Stabilized in Dextran Solution by Gamma Co-60 Ray Irradiation and Preparation of Gold Nanoparticles/Dextran Powder

Gold nanoparticles (AuNPs) in spherical shape with diameter of 6–35 nm stabilized by dextran were synthesized by γ-irradiation method. The AuNPs were characterized by UV-Vis spectroscopy and transmission electron microscopy. The influence of pH, Au3

The theoretical study on nickel(II) amide complexes of carbon and carbene: new suggested molecules as fertilizers for plants

Quantum chemical calculations at the gradient-corrected (BP86) density-functional theory (DFT) with various basis sets (SVP, TZVPP, TZ2P+) are carried out to calculate for the first time the bonding situation of nickel(II) amide complexes of carbon Ni(NH 2 ) 2 –C(PH 3 ) 2 ( Ni2-CP2 ) and carbene Ni(NH 2 ) 2 –NHC Me ( Ni2-NHC Me ). The nature of the (NH 2 ) 2 Ni–C(PH 3 ) 2 and (NH 2 ) 2 Ni–NHC Me bonds was analyzed with charge- and energy decomposition methods. The calculated equilibrium structure of carbon complex Ni2-CP2 shows that ligand C(PH 3 ) 2 ( CP 2 ) are bonded in a tilted orientation relative to the fragment Ni(NH 2 ) 2 with the bending angle, α, of Ni2-CP2 is 146.1°. In contrast to this, the carbene complex Ni2-NHC Me possesses end-on-bonded NHC Me ligand with the bending angle, α, is 180°. The bond dissociation energy (BDE) for the Ni2-CP2 bond is slightly higher than for the Ni2-NHC Me bond. The low-valent chemistry of nickel(II) amide in Ni2-CP2 always receives electrons from the s lone-pair orbital of C(PH 3 ) 2 and the Ni-C bond has a small contribution from (NH 2 ) 2 Ni←C(PH 3 ) 2 π-donation. Although the carbon ligand has two lone-pairs orbitals for donation but the structure of carbon complex exhibits an unusual bonding at nickel(II) amide fragment. The EDA-NOCV results suggest that the CP2 ligand in the Ni2-CP2 is very strong s-donor and strong π-donor. The NHC Me ligand has only one lone pair for donation and the NHC Me ligand in the Ni2-NHC Me is strong s-donor and strong π-donor. The first results of this work not only give details the structures and chemical bonding of the molecules investigated, but also open up a field of research in the preparation of new molecules as fertilizers for plants. Keywords. Carbon, carbene, BDE; DFT; Bond dissociation energies (BDEs); Energy decomposition analysis (EDA); Natural Orbitals for Chemical Valence (NOCV).

Facile synthesis of α-Fe{sub 2}O{sub 3} nanoparticles for high-performance CO gas sensor

Highlights: • We have demonstrated a facile method to prepare Fe{sub 2}O{sub 3} nanoparticles. • The gas sensing properties of α-Fe{sub 2}O{sub 3} have been invested. • The results show potential application of α-Fe{sub 2}O{sub 3} NPs for CO sensors in environmental monitoring. - Abstract: Iron oxide nanoparticles (NPs) were prepared via a simple hydrothermal method for high performance CO gas sensor. The synthesized α-Fe{sub 2}O{sub 3} NPs were characterized by X-ray diffraction, nitrogen adsorption/desorption isotherm, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). The SEM, TEM results revealed that obtained α-Fe{sub 2}O{sub 3} particles had a peanut-like geometry with hemispherical ends. The response of the α-Fe{sub 2}O{sub 3} NPs based sensor to carbon monoxide (CO) and various concentrations of other gases were measured at different temperatures. It found that the sensor based on the peanut-like α-Fe{sub 2}O{sub 3} NPs exhibited high response, fast response–recovery, and good selectivity to CO at 300 °C. The experimental results clearly demonstrated the potential application of α-Fe{sub 2}O{sub 3} NPs as a good sensing material in the fabrication of CO sensor.

Preparation and characterization of superparamagnetic Fe3O4-chitosan nanocomposites

In this study, superparamagnetic nanocomposite Fe 3 O 4 -chitosan has been prepared by two step method. The Fe 3 O 4 nanoparticles were prepared by a co-precipitation process and subsequently coated with chitosan. The magnetite nanoparticles and chitosan coated magnetic nanoparticles were characterized by XRD, IR and TEM. The magnetic properties were measured with homemade vibrating sample magnetometer (VSM) and evaluated in terms of saturation magnetization and coercivity. The results revealed that typical iron oxide nanoparticles were Fe 3 O 4 with a core diameter of 15-20 nm. Magnetie nanoparticles were formed inside the chitosan matrix through possible binding of iron ions to NH 2 group of chitosan. The Fe 3 O 4 -chitosan nanoparticles with core-shell structure exhibit superparamagnetic properties and highly dispersed nano magnetite particles with diameters around 15 nm. Keywords: Fe 3 O 4 , chitosan, superparamagnetic nanocomposite, two step method.

Synthesis, characterization, and gas-sensing properties of alpha-Fe2O3 prepared from Fe3O4-alginate

In this study, nanocomposite Fe 3 O 4 –alginate has been prepared by so-called two step method. The crystal structures and morphologies of as-synthesized nanopaticles (NPs) were characterized X-ray diffraction, and scanning electron microscopy. The surface states of Fe 3 O 4 -alginate NPs were characterized by Fourier transform infrared spectra. a-Fe 2 O 3 was fabricated from the nanocomposite Fe 3 O 4 -alginate by heat treatment in air atmosphere at 600 o C and their gas sensing properties were investigated. The performance of the a-Fe 2 O 3 in the detection of toxic and flammable gases such as carbon oxide, ammonia, liquefied petroleum gas, ethanol, and hydrogen was evaluated. The Fe 2 O 3 based gas sensors exhibited high sensitivity and a response time of less than a minute to analytic gases. Keywords: Fe 2 O 3 , Fe 3 O 4 , gas sensor, alginate.

A study on the synthesis of gold nanoparticles using water soluble chitosan as reducing/stabilizing agent

Gold nanoparticles have been synthesized by utilizing water soluble chitosan (WSC) as reducing and stabilizing agent. The colloidal gold nanoparticles were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). The results showed that the morphology of gold nanoparticles was spherical in shape with diameters of about 6-17 nm. The colloidal gold nanoparticles were stable and had a plasmon absorption band with maximum wavelength in the range of 520-526 nm. Effects of concentration of Au 3+ , concentration of water soluble chitosan on the size and plasmon absorption band were also investigated. The size of gold nanoparticles could be enlarged from 14 up to about 35 nm by using seed growth method. Keywords: Gold nanoparticles, synthesis, water soluble chitosan, seed growth.