scholarly journals Supercapacitors based on graphene/pseudocapacitive materials

2017 ◽  
Vol 82 (4) ◽  
pp. 411-416
Author(s):  
Denis Sacer ◽  
Magdalena Kralj ◽  
Suzana Sopcic ◽  
Milica Kosevic ◽  
Aleksandar Dekanski ◽  
...  

Composites of graphene and SnO2 were successfully prepared by a single step simultaneous synthesis of SnO2 and reduction of graphene oxide (GO). Three different compositions of precursor solution resulted in different composite materials containing graphene and SnO2. The reaction was realized by microwave-assisted hydrothermal synthesis. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) gave insight into the morphology and composition of the obtained materials. Good capacitive/pseudocapacitive properties of the obtained material suitable for supercapacitor application were registered by cyclic voltammetry, from where specific capacitance values up to 93 F g-1 were determined.

2011 ◽  
Vol 284-286 ◽  
pp. 746-749
Author(s):  
Chong Hai Deng ◽  
Han Mei Hu ◽  
Ming Di Yang

In this paper, we reported a facile microwave-assisted green chemical route to prepare pure, uniform, and monodispersed Cu2O octahedron wrapped by the {111} faces by using glucose as a reducing agent. X-ray diffraction (XRD), energy dispersive X-ray spectrometry(EDX) and field emission scanning electron microscopy (FESEM) were used to characterize the as-synthesized products. It was found that the morphology and structure of Cu2O crystals were greatly affected by the concentration of NaOH. A solid-solution-solid growth mechanism was possibly proposed on the basis of the comparative experimental results.


2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
Lai zhenyu ◽  
Qian Jueshi ◽  
Lu Zhongyuan ◽  
Li Qian ◽  
Zou Qiulin

Dittmarite was obtained using MgO and (NH4)2HPO4as raw materials via microwave-assisted hydrothermal method for 3 min at 120°C. The resulting samples were investigated by X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetry-differential thermal analysis. The results indicate that dittmarite can be rapidly synthesized by microwave-assisted hydrothermal method. With higher temperature and longer reaction time, highly crystallized dittmarite can be obtained. Pure dittmarite can be synthesized for 3 min at 120°C, which is faster than with the use of any other reported methods.


e-Polymers ◽  
2017 ◽  
Vol 17 (3) ◽  
pp. 243-248 ◽  
Author(s):  
Weidong Han ◽  
Bin Ding ◽  
Mira Park ◽  
Fuhai Cui ◽  
Su-Hyeong Chae ◽  
...  

AbstractPoly(vinyl pyrrolidone) (PVP)/La3+/Zr4+ precursor nanofibrous membranes (LZPNM) with various Zr contents were synthesized via a simple electrospinning method. By controlling the Zr incorporation, the tensile properties of precursor membranes dramatically change from 0.77 to 1.73 MPa. Meanwhile, the average diameters of precursor nanofibers increase with the increase of Zr contents (from 283 to 535 nm). In addition, flexible La2O3-ZrO2 nanofibrous membranes (LZNM) were obtained by calcination of corresponding precursor membranes. Furthermore, the structures and morphologies of the precursor membranes were investigated using X-ray powder diffraction analysis (XRD) and field-emission scanning electron microscopy (FE-SEM). The surface functional groups and thermal properties of the precursor membranes were measured via Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA).


2016 ◽  
Vol 6 (1) ◽  
pp. 17
Author(s):  
Saule Kudaikulova ◽  
Galina Boiko ◽  
Bulat Zhubanov ◽  
N. Ashurov ◽  
Sh. Sodykov ◽  
...  

The formulation of macromolecular blends on the basis of polyimides using one step catalytic polycyclocondensation is reported. Polymers with active functional groups (polyacrylamide, polycaproamide) have been suggested as catalysts for the reaction of alicyclic dianhydrides with aromatic diamines in protolytic medium. Films made from macromolecular blends of synthesized polymers have been investigated by X-ray diffractometry and scanning electron microscopy. It has been shown that single step formation of polyimide on the polymer matrix presents the possibility to prepare thin structured disperse blends in comparison with simple mixing of homopolymers.


Nano Hybrids ◽  
2015 ◽  
Vol 9 ◽  
pp. 24-32
Author(s):  
Suresh Sagadevan

Bismuth tungstate (Bi2WO6) nanoparticles were synthesized by microwave assisted method. The prepared nanoparticles were investigated by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy and dielectric studies. The formation of Bi2WO6nanoparticles was confirmed by X-ray diffraction (XRD). The morphology of Bi2WO6nanoparticle was characterized using scanning electron microscopy SEM. The optical properties were studied by the UV-Visible absorption spectrum. The dielectric properties of Bi2WO6nanoparticles were studied. The activation energy was calculated from AC conductivity studies.Key words: Bi2WO6nanoparticles, XRD, SEM, TEM, UV analysis, Dielectric studies and AC conductivity studies


Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.


Author(s):  
M. L. Zimny ◽  
A. C. Haller

During hibernation the ground squirrel is immobile, body temperature reduced and metabolism depressed. Hibernation has been shown to affect dental tissues varying degrees, although not much work has been done in this area. In limited studies, it has been shown that hibernation results in (1) mobilization of bone minerals; (2) deficient dentinogenesis and degeneration of alveolar bone; (3) presence of calculus and tears in the cementum; and (4) aggrevation of caries and pulpal and apical tooth abscesses. The purpose of this investigation was to study the effects of hibernation on dental tissues employing scanning electron microscopy (SEM) and related x-ray analyses.


Author(s):  
Yun Lu ◽  
David C. Joy

High resolution scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA) were performed to investigate microparticles in blended cements and their hydration products containing sodium-rich chemical wastes. The physical appearance of powder particles and the morphological development at different hydration stages were characterized by using high resolution SEM Hitachi S-900 and by SEM S-800 with a EDX spectrometer. Microparticles were dispersed on the sample holder and glued by 1% palomino solution. Hydrated bulk samples were dehydrated by acetone and mounted on the holder by silver paste. Both fracture surfaces and flat cutting sections of hydrating samples were prepared and examined. Some specimens were coated with an 3 nm thick Au-Pd or Cr layer to provide good conducting surfaces. For high resolution SEM S-900 observations the accelerating voltage of electrons was 1-2 KeV to protect the electron charging. Microchemical analyses were carried out by S800/EDS equipped with a LINK detector of take-off angle =40°.


Author(s):  
M.G. Baldini ◽  
S. Morinaga ◽  
D. Minasian ◽  
R. Feder ◽  
D. Sayre ◽  
...  

Contact X-ray imaging is presently developing as an important imaging technique in cell biology. Our recent studies on human platelets have demonstrated that the cytoskeleton of these cells contains photondense structures which can preferentially be imaged by soft X-ray imaging. Our present research has dealt with platelet activation, i.e., the complex phenomena which precede platelet appregation and are associated with profound changes in platelet cytoskeleton. Human platelets suspended in plasma were used. Whole cell mounts were fixed and dehydrated, then exposed to a stationary source of soft X-rays as previously described. Developed replicas and respective grids were studied by scanning electron microscopy (SEM).


Author(s):  
Howard S. Kaufman ◽  
Keith D. Lillemoe ◽  
John T. Mastovich ◽  
Henry A. Pitt

Gallstones contain precipitated cholesterol, calcium salts, and proteins. Calcium (Ca) bilirubinate, palmitate, phosphate, and carbonate occurring in gallstones have variable morphologies but characteristic windowless energy dispersive x-ray (EDX) spectra. Previous studies of gallstone microstructure and composition using scanning electron microscopy (SEM) with EDX have been limited to dehydrated samples. In this state, Ca bilirubinates appear as either glassy masses, which predominate in black pigment stones, or as clusters, which are found mostly in cholesterol gallstones. The three polymorphs of Ca carbonate, calcite, vaterite, and aragonite, have been identified in gallstones by x-ray diffraction, however; the morphologies of these crystals vary in the literature. The purpose of this experiment was to study fresh gallstones by environmental SEM (ESEM) to determine if dehydration affects gallstone Ca salt morphology.Gallstones and bile were obtained fresh at cholecystectomy from 6 patients. To prevent dehydration, stones were stored in bile at 37°C. All samples were studied within 4 days of procurement.


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