scholarly journals One-Pot Microwave-Assisted Synthesis of Graphene-Supported PtCoM (M = Mn, Ru, Mo) Catalysts for Low-Temperature Fuel Cells

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1431
Author(s):  
Antanas Nacys ◽  
Teofilius Kilmonis ◽  
Virginija Kepenienė ◽  
Aldona Balčiūnaitė ◽  
Raminta Stagniūnaitė ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Microwave Assisted Synthesis ◽  
Electrochemical Characteristics ◽  
One Pot ◽  
Molar Ratios ◽  
Microwave Assisted ◽  
Transmission Electron ◽  
Low Temperature Fuel Cells ◽  
A Current

In this study, one-pot microwave-assisted synthesis was used to fabricate the graphene (GR)-supported PtCoM catalysts where M = Mn, Ru, and Mo. The catalysts with the molar ratios of metals Pt:Co:Mn, Pt:Co:Ru, and Pt:Co:Mo equal to 1:3:1, 1:2:2, and 7:2:1, respectively, were prepared. Catalysts were characterized using Transmission Electron Microscopy (TEM). The electrocatalytic activity of the GR-supported PtCoMn, PtCoRu, and PtCoMo catalysts was evaluated toward methanol oxidation in an alkaline medium employing cyclic voltammetry and chrono-techniques. The most efficient electrochemical characteristics demonstrated the PtCoMn/GR catalyst with a current density value of 144.5 mA cm−2, which was up to 4.8 times higher than that at the PtCoRu(1:2:2)/GR, PtCoMo(7:2:1)/GR, and bare Pt/GR catalysts.

Microwave-assisted synthesis of various gallium oxyhydroxide nanorods and their controllable conversion into different gallium oxide polymorphs

2009 ◽  
Vol 24 (7) ◽  
pp. 2268-2275 ◽  
Author(s):  
Suxiang Ge ◽  
Lizhi Zhang ◽  
Huimin Jia ◽  
Zhi Zheng
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gallium Oxide ◽  
Disodium Salt ◽  
Microwave Assisted Synthesis ◽  
X Ray Diffraction ◽  
Microwave Assisted ◽  
Transmission Electron ◽  
Oxide Nanorods ◽  
Microwave Assisted Method

Various α-GaOOH nanorods were synthesized through a microwave-assisted method at 80 °C. In the synthesis, Ga(NO3)3 was used as the gallium source, and urea, L-cysteine, and EDTA disodium salt were used as the additives. The thermal decomposition of the as-prepared α-GaOOH nanorods could selectively produce α-, β-, and ε-Ga2O3 nanorods. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and cathodoluminescence were used to characterize the resulting samples. On the basis of characterization results, the possible growth mechanisms of these various GaOOH nanorods were proposed. This study provides a controllable method to prepare various gallium oxyhydroxide and gallium oxide nanorods.

scholarly journals Fast Microwave-Assisted Synthesis and Photoluminescence of CaWO4Nanocrystals

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Quanguo Li ◽  
Yanhua Shen ◽  
Taohai Li
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Microwave Assisted Synthesis ◽  
X Ray ◽  
Microwave Assisted ◽  
Transmission Electron ◽  
Ft Ir ◽  
Microwave Assisted Method

In this work, CaWO4nanoparticles have been synthesized by microwave-assisted method at a low temperature of 120°C. The as-prepared powders were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). It is found that the reaction time played an important role in the morphology controlling and crystallinity level of CaWO4crystals. The effects of photoluminescent properties have a great relationship with crystallinity.

Synthesis Route towards Fine and Monodisperse Ni Nanoparticles via Hot-Injection Approach

2013 ◽  
Vol 393 ◽  
pp. 146-151 ◽  
Author(s):  
N.R. Nik Roselina ◽  
Aziz Azizan ◽  
Koay Mei Hyie ◽  
C.M. Mardziah ◽  
Salmiah Kasolang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Size Distribution ◽  
Reaction Rate ◽  
Fine Particles ◽  
Synthesis Temperature ◽  
Ni Nanoparticles ◽  
One Pot ◽  
Transmission Electron ◽  
Hot Injection

Manipulation of adding sequences have been found to influence the reaction rate, thus made it easier to produced controllable Ni nanoparticles. Hot-injection approach shown capability to significantly reduce the production time of Ni nanoparticles compared to the conventional one-pot synthesis. With minor modification on conventional polyol method, narrow, monodispersed and highly yield spherical nickel (Ni) nanoparticles were successfully produced at synthesis temperature of 60°C. Three mixing methods were investigated to study its efficiency towards producing rapid and narrower size distribution of Ni nanoparticles. Reduction processes were proposed each of the method. As-synthesized Ni nanoparticles were characterized with Transmission Electron Microscopy (TEM), Scanning Transmission Electron Microscopy (STEM) and Fourier transform infrared spectroscopy (FTIR) to analyze the size, morphology and interaction of reactants. Fine particles size distribution revealed that when hydrazine was first heated, reaction rate improved tremendously.

scholarly journals Biomineralization of Monohydrocalcite Induced by the Halophile Halomonas smyrnensis WMS‐3

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 632 ◽  
Author(s):  
Pan ◽  
Zhao ◽  
Tucker ◽  
Zhou ◽  
Jiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Carbon Isotope ◽  
Extracellular Polymeric Substances ◽  
Salt Lake ◽  
Stable Carbon Isotope ◽  
Ion Concentration ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Halomonas Smyrnensis

The halophilic bacterium Halomonas smyrnensis from a modern salt lake used in experiments to induce biomineralization has resulted in the precipitation of monohydrocalcite and other carbonate minerals. In this study, a Halomonas smyrnensis WMS‐3 (GenBank:MH425323) strain was identified based on 16S rDNA homology comparison, and then cultured in mediums with 3% NaCl concentration to induce monohydrocalcite at different Mg/Ca molar ratios of 0, 2, 5, 7, and 9. The growth curve of WMS‐3 bacteria, pH values, NH4+ concentration, HCO3− and CO32− concentration, carbonic anhydrase (CA) activity, and the changes in Ca2+ and Mg2+ ion concentration were determined to further explore the extracellular biomineralization mechanism. Moreover, the nucleation mechanism of monohydrocalcite on extracellular polymeric substances (EPS) was analyzed through studying ultrathin slices of the WMS‐3 strain by High resolution transmission electron microscopy (HRTEM), Selected area election diffraction (SAED), Scanning transmission electron microscopy (STEM), and elemental mapping, besides this, amino acids in the EPS were also analyzed. The results show that pH increased to about 9.0 under the influence of ammonia and CA activity. The precipitation ratio (%, the ratio of the mass/volume concentration) of the Ca2+ ion was 64.32%, 62.20%, 60.22%, 59.57%, and 54.42% at Mg/Ca molar ratios of 0, 2, 5, 7, and 9, respectively, on the 21st day of the experiments, and 6.69%, 7.10%, 7.74%, 8.09% for the Mg2+ ion concentration at Mg/Ca molar ratios 2, 5, 7, and 9, respectively. The obtained minerals were calcite, Mg‐rich calcite, aragonite, and hydromagnesite, in addition to the monohydrocalcite, as identified by X-ray diffraction (XRD) analyses. Monohydrocalcite had higher crystallinity when the Mg/Ca ratio increased from 7 to 9; thus, the stability of monohydrocalcite increased, also proven by the thermogravimetry (TG), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC) analyses. The C=O and C–O–C organic functional groups present in/on the minerals analyzed by Fourier transform infrared spectroscopy (FTIR), the various morphologies and the existence of P and S determined by scanning electron microscope-energy dispersive spectrometer (SEM‐EDS), the relatively more negative stable carbon isotope values (−16.91‰ to −17.91‰) analyzed by a carbon isotope laser spectrometer, plus the typical surface chemistry by XPS, all support the biogenesis of these mineral precipitates. Moreover, Ca2+ ions were able to enter the bacterial cell to induce intracellular biomineralization. This study is useful to understand the mechanism of biomineralization further and may provide theoretical reference concerning the formation of monohydrocalcite in nature.

scholarly journals Microwave-assisted synthesis and characterization of microstar shaped zinc oxide

Quimica Hoy ◽  
2012 ◽  
Vol 2 (3) ◽  
pp. 3
Author(s):  
Idalia Gómez ◽  
Miguel José Yucam´án ◽  
Flor Palomar
Keyword(s):  
Electron Microscopy ◽  
Zinc Oxide ◽  
Microwave Assisted Synthesis ◽  
Stoichiometric Ratio ◽  
Crystalline Materials ◽  
Microwave Assisted ◽  
Transmission Electron ◽  
Synthesis Procedure ◽  
Post Synthesis

A microwave-assisted solution-phase approach has been applied for the synthesis ofzinc oxide microstructures. Toe synthesis procedure was carried out by using the reagents: Zinc ni trate and Methenamine, at stoichiometric ratio. Analysis by means ofX-ray Diffraction (XRD) shows a crystalline phase in hexagonal wurtzite arrangement for ZnO. The presence ofmicrostar shaped zinc oxide (2-3μm) with nanorods,f50nm) arranged has been confirmed from High Resolution Scanning Electron Microscopy (HRSEM). The formation of nanorods was confirmed by Transmission Electron Microscopy. In Raman spectroscopy a red shift was detected in the microstructures compared with ZnO bulk. High crystalline materials without additional post-synthesis treatrnent were found.

A Study of Gaseous and Organic Inclusions in Copper Electrodeposit by Transmission Electron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 644-645
Author(s):  
S. Nakahara ◽  
A. Staudinger
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Copper Film ◽  
Organic Additive ◽  
Sulfate Electrolyte ◽  
Copper Sheet ◽  
Transmission Electron ◽  
Copper Electrodeposit ◽  
A Current

It was recently shown (1) that gaseous and organic inclusions in electrodeposits can he detected "by transmission electron microscopy (TEM) using a through-focus imaging technique. In this study, we have investigated the sites for incorporation of inclusions and their spacial distribution in copper electrodeposit by TEM.A copper film was electrodeposited on an annealed OFHC copper sheet in a sulfate electrolyte (200 g/l CuSo4-5H2O, 50 g/l H2So4) containing 5 M Mol./l O-phenanthroline as an organic additive. Plating was carried out at room temperature and at a current density of 5 MA/cm2.In order to detect gaseous and organic inclusions, all copper deposits were examined in overfocussed as well as underfocussed conditions. In each case, stereo-pairs(2) were obtained. Figures 1 and 2 show stereo-pairs of the deposited copper film taken in overfocussed and underfocussed conditions, respectively.

Rapid Synthesis of Uniform CdSe Nanorods by a Microwave-Assisted Solvothermal Method in Ethylenediamine

2020 ◽  
Vol 20 (10) ◽  
pp. 6495-6499
Author(s):  
Maokun Han ◽  
Ruijuan Qi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Solvothermal Method ◽  
X Ray Diffraction ◽  
Rapid Synthesis ◽  
X Ray ◽  
Microwave Assisted ◽  
Aspect Ratios ◽  
Transmission Electron ◽  
Cdse Nanorods

A rapid microwave-assisted solvothermal method is reported for the synthesis of uniform CdSe nanorods in ethylenediamine (EDA) using CdCl2 and elemental Se as reactants. The resultant nanorods have a diameter of approximately 10 nm and a length of approximately 300 nm. Our experiments show that the concentrations of EDA and CdCl2 play important roles in product morphology. The well-dispersed CdSe nanorods with high aspect ratios were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), UV-vis absorption and photoluminescence (PL).

scholarly journals Facile one-pot synthesis of water-soluble fcc FePt3 alloy nanostructures

2020 ◽  
Vol 2 (10) ◽  
Author(s):  
Melek Kızaloğlu Akbulut ◽  
Christina Harreiß ◽  
Mario Löffler ◽  
Karl J. J. Mayrhofer ◽  
Michael Schöbitz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Water Soluble ◽  
Alloy Nanoparticles ◽  
One Pot ◽  
X Ray ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

Abstract Proccessible FePt3 alloy nanoparticles with sizes smaller than 50 nm open the avenue to novel magnetic sensor, catalytic and biomedical applications. Our research objective was to establish a highly scalable synthesis technique for production of single-crystalline FePt3 alloy nanoparticles. We have elaborated a one-pot thermal decomposition technique for the synthesis of superparamagnetic FePt3 nanoparticles (FePt3 NPs) with mean sizes of 10 nm. Subsequent tiron coating provided water solubility of the FePt3 NPs and further processibility as bidental ligands enable binding to catalyst surfaces, smart substrates or biosensors. The chemical composition, structure, morphology, magnetic, optical and crystallographic properties of the FePt3 NPs were examined using high resolution transmission electron microscopy, high-angle annular dark field-scanning transmission electron microscopy, scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy mapping, Fourier transform infrared-attenuated total reflection, X-ray powder diffraction, X-ray photoelectron spectroscopy, vibrating sample magnetometry and UV–Vis absorption spectroscopy.

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