Controllable synthesis, characterization, and electrochemical properties of manganese oxide nanoarchitectures

2008 ◽  
Vol 23 (3) ◽  
pp. 780-789 ◽  
Author(s):  
Lichun Zhang ◽  
Liping Kang ◽  
Hao Lv ◽  
Zhikui Su ◽  
Kenta Ooi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electrochemical Properties ◽  
Manganese Oxide ◽  
Manganese Oxides ◽  
Hydrothermal Reaction ◽  
Reaction Times ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
Hydrothermal Temperature ◽  
Transmission Electron

Flowerlike manganese oxide microspheres and cryptomelane-type manganese oxide nanobelts were selectively synthesized by a simple decomposition of KMnO4 under mild hydrothermal conditions without using template or cross-linking reagents. The effect of varying the hydrothermal times and temperatures on the nanostructure, morphology, compositional, and electrochemical properties of the obtained manganese oxides was investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies showed that the flowerlike manganese oxide microspheres could be obtained at relatively low hydrothermal temperatures, while high hydrothermal temperatures were favorable for the formation of cryptomelane-type manganese oxide nanobelts. A morphology and crystalline evolution of the nanostructures was observed as the hydrothermal temperature was increased from 180 to 240 °C. On the basis of changing the temperatures and hydrothermal reaction times, the formation mechanism of cryptomelane-type manganese oxide nanobelts is discussed. Cyclic voltammetry (CV) was used to evaluate the electrochemical properties of the obtained manganese oxide nanostructures, and the results show that the electrochemical properties depend on their shape and crystalline structure. This easily controllable, template-free, and environmentally friendly method has the potential for being used in syntheses of manganese oxide nanomaterials with uniform morphologies and crystal structures.

Facile Controlled Synthesis of Manganese Oxide Hierarchical Microspheres by Hydrothermal Method

2011 ◽  
Vol 688 ◽  
pp. 107-115 ◽  
Author(s):  
Dong Yan Li ◽  
Yun Fa Chen
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Reaction ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Formation Mechanisms ◽  
X Ray Diffraction ◽  
Tem Analysis ◽  
Hydrothermal Temperature ◽  
Transmission Electron ◽  
Hierarchical Microspheres

MnO2hierarchical microsphere has been synthesized by a facile and direct hydrothermal reaction between KMnO4and HCl without the aids of catalysts, surfactants or templates. The as-prepared microsphere, as characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) analysis and nitrogen adsorption and desorption, is in form of K0.27MnO2(H2O )0.54, with a flower-like hierarchical microsphere structure and a BET surface area value of 52 m2/g. The morphology of the product can be simply tailed by controlled by reaction temperature or period and crystallinity can be modified by changing the concentrate of KMnO4. In general, excessive KMnO4and low hydrothermal temperature are favor to forming flower-like hierarchical structure. Besides, the formation mechanisms of the hierarchical schemes are proposed.

Characterization of Hydroxyapatite by Electron Microscopy

2005 ◽  
Vol 11 (6) ◽  
pp. 516-523 ◽  
Author(s):  
V. Rodríguez-Lugo ◽  
J. Sanchez Hernández ◽  
Ma. J. Arellano-Jimenez ◽  
P.H. Hernández-Tejeda ◽  
S. Recillas-Gispert
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Reaction Times ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Transmission Electron ◽  
Magnesian Calcite ◽  
Scanning Electron

The obtention of hydroxyapatite (HAp) is reported using brushite (CaHPO4·2H2O) and the skeleton of a starfish (Mellita eduardobarrosoi sp. nov.), primarily composed of magnesian calcite ((Ca,Mg)CO3) as precursors. Stoichiometric amounts of both were reacted under hydrothermal conditions: a pressure of 5.8 MPa and a temperature of 200°C for 2, 4, 6, 8, 10, and 20 h of reaction times. The samples obtained were characterized by means of scanning electron microscopy, X-ray diffraction, infrared spectroscopy, and transmission electron microscopy. Two defined populations of HAp fibers were found: A bundle of fibers 75 μm in length and 1–13 μm in diameter, and a second bundle of fibers 5 μm in length and less than 0.5 μm in diameter. Furthermore, an increase in HAp formation and a Ca/P ratio as a function of reaction time were observed. The growth mechanism of HAp is also discussed.

Effect of hydrothermal dwell time on the diameter-controlled synthesis and magnetic property of MnO2 nanorods

2014 ◽  
Vol 28 (06) ◽  
pp. 1450045 ◽  
Author(s):  
Arbab Mohammad Toufiq ◽  
Fengping Wang ◽  
Qurat-ul-Ain Javed ◽  
Yan Li
Keyword(s):  
Electron Microscopy ◽  
Reaction Time ◽  
Dwell Time ◽  
Hydrothermal Reaction ◽  
Ferromagnetic Behavior ◽  
X Ray Diffraction ◽  
Hydrothermal Route ◽  
Transmission Electron ◽  
Facile Hydrothermal Route ◽  
Hydrothermal Reaction Time

In this paper, single crystalline 1D tetragonal MnO 2 pen-type nanorods were synthesized by varying the dwell time through a facile hydrothermal route at a reaction temperature of 250°C. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies showed that the diameter of MnO 2 nanorods decreases from 460 nm to 250 nm with the increase in hydrothermal reaction time from 5 h to 15 h. Field-emission scanning electron microscopy (FESEM) and TEM studies revealed the evolution of improved surface morphology of MnO 2 nanorods that are prepared with longer hydrothermal reaction time. The magnetic properties of the products were evaluated using vibrating sample magnetometer (VSM) at room temperature, which showed that the as-prepared samples exhibit weak ferromagnetic behavior. The effect of diameter on the magnetization values was observed and discussed in detail.

Evolution of Crystalline Phase and Morphology of the Products Formed during the Hydrothermal Synthesis of Y2O3 Powders

2011 ◽  
Vol 189-193 ◽  
pp. 1275-1279
Author(s):  
Ying Wang ◽  
Gao Yang Zhao ◽  
Li Yuan
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Treatment ◽  
Crystalline Phase ◽  
Hydrothermal Reaction ◽  
Yttrium Nitrate ◽  
Temperature Reaction ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
X Ray ◽  
Transmission Electron

The crystalline phase and morphology of the products formed during the synthesis of yttrium oxide via the hydrothermal treatment yttrium nitrate were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Products with high OH/NO3ratios are formed with the increasing of hydrothermal treatment. The crystalline phases are evolved from Y2(OH)5.14(NO3)0.86•H2O toY4O(OH)9(NO3) and finally Y(OH)3. The hydrothermal reaction conditions play an important role in the synthesis of the microstructures. Results show the particle size and final morphology of samples could be controlled by reaction temperature, reaction time, and OH-concentration. Sheets, hexagonal and needle-like Y2O3powders are obtained with the hydrothermal treatment of yittrium nitrate at 180 oC to 200oC for 2-8 hours at pH 9-13.

Hydrothermal Synthesis and Morphology Evolution of Perovskite PbTiO3 Crystals with Different Lead Sources

2013 ◽  
Vol 745-746 ◽  
pp. 309-314 ◽  
Author(s):  
Si Min Yin ◽  
Gang Xu ◽  
Zhao Hui Ren ◽  
Chun Ying Chao ◽  
Ge Shen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Hydrothermal Reaction ◽  
Reaction System ◽  
Morphology Evolution ◽  
X Ray Diffraction ◽  
Reaction Route ◽  
X Ray ◽  
Transmission Electron ◽  
Lead Source

Perovskite lead titanate crystals with various morphologies were successfully synthesized via a hydrothermal reaction route with different lead sources. X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) were employed to characterize the phase composition and the morphology of the synthesized products. In order to investigate the effect of the lead source on the phase formation and morphology evolution of the synthesized pervoskite PbTiO3 crystals, PbO, PbF2, PbSO4 and Pb (CH3COO)3 ·3H2O, were used as starting precursor lead source introduced into the hydrothermal reaction system, respectively. Accordingly, perovskite PbTiO3 brken cubes, irregular particles, cubic particles, and microplates were obtained, respectively. Based on the experimental results, the effect of lead source was simply discussed.

H2 Uptake and Synthesis of the Li-dispersed Manganese Oxide Nanotubes

2007 ◽  
Vol 7 (11) ◽  
pp. 4033-4036 ◽  
Author(s):  
Jin Bae Lee ◽  
Soon Chang Lee ◽  
Hae Jin Kim
Keyword(s):  
Electron Microscopy ◽  
Manganese Oxide ◽  
Hydrogen Adsorption ◽  
Gravimetric Method ◽  
Anodic Aluminum Oxide Template ◽  
Outer Diameter ◽  
X Ray Diffraction ◽  
Anodic Aluminum ◽  
Transmission Electron ◽  
Potential Applications

Well aligned Li-dispersed manganese oxide nanotubes were prepared using LiNO3, Mn(NO3)2 · xH2O and an anodic aluminum oxide template by solvent-free method for potential applications in H2 storage. The obtained nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The analyses revealed the Mn2O3 nanotubes to have a cubic structure with a uniform length, 40–50 nm in wall thickness and 250 ± 10 nm in the outer diameter. The level of H2 adsorption was determined using the gravimetric method. The Li-dispersed manganese oxide nanotubes showed a 0.26 wt% for the amount of hydrogen adsorption at 77 K under 4.5 MPa.

Preparation and Spectral Properties of PVP-Modified ZnO Nanorods

2008 ◽  
Vol 368-372 ◽  
pp. 329-332 ◽  
Author(s):  
Yang Feng Huang ◽  
Han Ning Xiao ◽  
Shu Guang Chen
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Reaction ◽  
Uv Spectroscopy ◽  
Zno Nanorods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uv Emission ◽  
Transmission Electron ◽  
Light Region ◽  
Uv Absorption Spectrum

ZnO nanorods were prepared by a hydrothermal reaction in the presence or absence of PVP (polyvinyl pyrrolidone). The obtained products were characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, UV-Vis absorption (UV) spectroscopy and photoluminescence (PL) spectroscopy. The results suggest that PVP plays an important role in the preparation of ZnO nanorods. The UV absorption spectrum showed PVP increases the UV-shielding ability but doesn’t influence the transparency in the visible light region. A weak UV emission at 353 nm of PL spectra exhibit the surface of ZnO nanorods is passivated and oxygen-related defects is supplied by PVP.

Structure and Photoluminescent Properties of Microstructural YBO3 : Eu3+ Nanocrystals

2007 ◽  
Vol 7 (2) ◽  
pp. 593-601 ◽  
Author(s):  
Guohui Pan ◽  
Hongwei Song ◽  
Lixin Yu ◽  
Zhongxin Liu ◽  
Xue Bai ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Luminescent Properties ◽  
Radiative Transition ◽  
Surface Site ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
Hydrothermal Temperature ◽  
Transmission Electron ◽  
Site Selective ◽  
Radiative Transition Rate

YBO3 : Eu3+ nanocrystals (NCs) were prepared by a hydrothermal method and characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The results demonstrate that morphology and structure of the NCs varied strongly with hydrothermal temperature. Their luminescent properties were investigated in comparison to the bulk. A large number of NO&minus3 groups were adsorbed at the surface of hydrothermal products, which acted as luminescent killers; Two symmetry sites of Eu3+ ions in NCs, the interior and the surface sites, were identified by the site-selective excitation and time-resolved emission experiments; The intensity ratio of 5D0–7F2 to 5D0–7F1 of Eu3+ at the surface site increased greatly than that at the interior site; as a result, the chromaticity was improved; The total radiative transition rate of 5D0–ΣJ7Fj for Eu3+ at the surface site was 3–5 times larger than that at the interior.

Prepare of the New Structure PbTiO3 Nanowires and the Study of the Reversible Bending

2013 ◽  
Vol 331 ◽  
pp. 522-526
Author(s):  
Jiang Wang ◽  
Jian Li ◽  
You Wen Wang
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stainless Steel ◽  
Hydrothermal Reaction ◽  
The Self ◽  
X Ray Diffraction ◽  
Electron Backscattered Diffraction ◽  
X Ray ◽  
Transmission Electron

When the self-made with Teflon lined with stainless steel reaction kettle is used to produce PbTiO3 nanowires with the adoption of hydrothermal reaction , PbTiO3 nanowires with new structure can be made when Pb/Ti equals 2.2. Observed through the Transmission Electron Microscopy (TEM), the bending feature of the PbTiO3 nanowires can be observed for several times when X-ray diffraction (XRD) and Electron Backscattered Diffraction (EBSD) are used to analyse and test the crystal structure of the nanowires. The result of the study shows that the degree of the bending of the PbTiO3 nanowires varies with the intensity of the electron beam from the Transmission Electron Microscopy, and its process can be reversible.

The Preparation and Properties of Seawater Purification and Resource Recycling Function Materials

2011 ◽  
Vol 233-235 ◽  
pp. 677-679
Author(s):  
Qi Huang ◽  
Wei Ma ◽  
Mei Han
Keyword(s):  
Electron Microscopy ◽  
Manganese Oxide ◽  
Spinel Structure ◽  
Lithium Manganese Oxide ◽  
Phenol Removal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resource Recycling ◽  
Lithium Manganese ◽  
Transmission Electron

A kind of manganese oxide which could purify seawater arisesed at the historic moment. Lithium manganese oxide was synthesized by coprecipitation method and the manganese oxide was prepared by extracting lithium from lithium manganese oxide. The characteristics of the manganese oxide were studied by X-ray diffraction and transmission electron microscopy. The characteristics showed that the manganese oxide was pure spinel structure and about 100 nm in length. There were experiments to study the effects of oil and phenol removal in the seawater. At the same time recycling lithium from seawater was tested. The results showed that the manganese oxide could not only remove oil and phenol but also recycle lithium.

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