A Comparative Study of Potentiostatic and Potentiodynamic Method in the Synthesis of MnO2 Films for Electrochemical Capacitors

2011 ◽  
Vol 239-242 ◽  
pp. 501-505 ◽  
Author(s):  
Ling Bin Kong ◽  
Rui Juan Bai ◽  
Yong Chun Luo ◽  
Long Kang
Keyword(s):  
Specific Capacitance ◽  
Nickel Foam ◽  
Three Dimensional ◽  
High Rate ◽  
X Ray Diffraction ◽  
Ac Impedance Spectroscopy ◽  
X Ray ◽  
Rate Discharge ◽  
High Rate Discharge ◽  
Potentiodynamic Method

Nanostructured ε-manganese dioxide films are deposited directly on three-dimensional nickel foam (NF) from 0.25 M Mn(CH3COO)2 by means of the potentiostatic method (PSM) and potentiodynamic method (PDM). The prepared MnO2 films are characterized by X-ray diffraction and scanning electron microscopy. The electrochemical properties of MnO2 films are investigated by cyclic voltammetry (CV), charge-discharge tests, and alternating current (AC) impedance spectroscopy. The results show that the PSM-MnO2 films exhibit higher specific capacitance and better high-rate discharge ability, which are more promising for applications in supercapacitor than PDM-MnO2 films. The specific capacitance of PSM-MnO2 films is about 664 F g-1 at 5.5 A g-1, which is higher than many reported values.

scholarly journals Binder free three-dimensional sulphur/few-layer graphene foam cathode with enhanced high-rate capability for rechargeable lithium sulphur batteries

Nanoscale ◽  
2014 ◽  
Vol 6 (11) ◽  
pp. 5746-5753 ◽  
Author(s):  
Kai Xi ◽  
Piran R. Kidambi ◽  
Renjie Chen ◽  
Chenlong Gao ◽  
Xiaoyu Peng ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Rate Capability ◽  
High Rate ◽  
High Rate Capability ◽  
Capacity Retention ◽  
Layer Graphene ◽  
Binder Free ◽  
Rate Discharge ◽  
Few Layer Graphene ◽  
High Rate Discharge

A novel ultra-lightweight 3-D Li-S battery cathode has been synthesised by loading sulphur on to an interconnected 3-D network of few-layered graphene. The battery shows high rate discharge capacity retention for up to 400 cycles.

Synthesis of Three Dimensional Graphene/Multiwalled Carbon Nanotubes Nanocomposites Hydrogel and Investigation of their Electrochemical Properties as Electrodes of Supercapacitors

2015 ◽  
Vol 1094 ◽  
pp. 222-228
Author(s):  
Lei Zhou ◽  
Da Wei He ◽  
Hong Lu Wu ◽  
Zeng Hui Qiu
Keyword(s):  
Carbon Nanotubes ◽  
Specific Capacitance ◽  
Multiwalled Carbon Nanotubes ◽  
Synthesis Method ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Multiwalled Carbon ◽  
X Ray ◽  
Transmission Electron ◽  
Reduced Graphene

A facile synthesis method of three dimensional reduced graphene oxide (RGO)/multiwalled carbon nanotubes (MWCNTs) hydrogel was introduced. Hydrogel samples which were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM) and examined by X-ray diffraction (XRD) have been used as the electrode of supercapacitor. Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) were used to investigate the Supercapacitors which we have fabricated. Because MWCNTs inserting into layers of RGO homogeneously prevent the layers of RGO from stacking and enlarge the specific surface area of graphene, the specific capacitance of RGO/MWCNTs material has been greatly improved. At the current density of 0.2A/g, the specific capacitance of RGO/MWCNTs electrode is about 176F/g, which means a 52% increasement compared to which of pure RGO material electrode. And the specific capacitance of RGO/MWCNTs also achieves a good rate property.

A facile synthesis of three dimensional graphene sponge composited with sulfur nanoparticles for flexible Li–S cathodes

2016 ◽  
Vol 18 (32) ◽  
pp. 22146-22153 ◽  
Author(s):  
Chao Lin ◽  
Chaojiang Niu ◽  
Xu Xu ◽  
Ke Li ◽  
Zhengyang Cai ◽  
...  
Keyword(s):  
Self Assembly ◽  
Three Dimensional ◽  
High Rate ◽  
Sulfur Cathode ◽  
Facile Synthesis ◽  
Capacity Retention ◽  
Assembly Method ◽  
Graphene Sponge ◽  
Rate Discharge ◽  
High Rate Discharge

A novel 3DGS was fabricatedviaa reduction induced self-assembly method. When used as a sulfur cathode, it shows high rate discharge capacity retention up to 500 cycles.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

scholarly journals An investigation of polyhedral deformation in two mixed-metal diarsenates: SrZnAs2O7and BaCuAs2O7

2015 ◽  
Vol 71 (4) ◽  
pp. 330-337 ◽  
Author(s):  
Sabina Kovač ◽  
Ljiljana Karanović ◽  
Tamara Đorđević
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
General Formula ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Open Framework ◽  
Geometrical Characteristics ◽  
Barium Copper

Two isostructural diarsenates, SrZnAs2O7(strontium zinc diarsenate), (I), and BaCuAs2O7[barium copper(II) diarsenate], (II), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction. The three-dimensional open-framework crystal structure consists of corner-sharingM2O5(M2 = Zn or Cu) square pyramids and diarsenate (As2O7) groups. Each As2O7group shares its five corners with five differentM2O5square pyramids. The resulting framework delimits two types of tunnels aligned parallel to the [010] and [100] directions where the large divalent nine-coordinatedM1 (M1 = Sr or Ba) cations are located. The geometrical characteristics of theM1O9,M2O5and As2O7groups of known isostructural diarsenates, adopting the general formulaM1IIM2IIAs2O7(M1II= Sr, Ba, Pb;M2II= Mg, Co, Cu, Zn) and crystallizing in the space groupP21/n, are presented and discussed.

Electrospun graphene-wrapped Na6.24Fe4.88(P2O7)4 nanofibers as a high-performance cathode for sodium-ion batteries

2017 ◽  
Vol 19 (26) ◽  
pp. 17270-17277 ◽  
Author(s):  
Yubin Niu ◽  
Maowen Xu ◽  
Chunlong Dai ◽  
Bolei Shen ◽  
Chang Ming Li
Keyword(s):  
Discharge Capacity ◽  
High Performance ◽  
Electronic Conductivity ◽  
Sodium Ion ◽  
High Rate ◽  
Sodium Ion Batteries ◽  
Rate Discharge ◽  
High Rate Discharge

Na6.24Fe4.88(P2O7)4 is one of the intensively investigated polyanionic compounds and has shown high rate discharge capacity, but its relatively low electronic conductivity hampers the high performance of the batteries.

A new model for packing of type-I collagen molecules in the native fibril

1981 ◽  
Vol 1 (10) ◽  
pp. 801-810 ◽  
Author(s):  
Karl A. Piez ◽  
Benes L. Trus
Keyword(s):  
Type I Collagen ◽  
Hexagonal Lattice ◽  
Three Dimensional ◽  
Equatorial Region ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Left Handed ◽  
Crystal Model ◽  
Collagen Molecules

A specific fibril model is presented consisting of bundles of five-stranded microfibrils, which are usually disordered (except axially) but under lateral compression become ordered. The features are as follows (where D = 234 residues or 67 nm): (1) D-staggered collagen molecules 4.5 D long in the helical microfibril have a left-handed supercoil with a pitch of 400–700 residues, but microfibrils need not have helical symmetry. (2) Straight-tilted 0.5-D overlap regions on a near-hexagonal lattice contribute the discrete x-ray diffraction reflections arising from lateral order, while the gap regions remain disordered. (3) The overlap regions are equivalent, but are crystallographically distinguished by systematic displacements from the near-hexagonal lattice. (4) The unit cell is the same as in a recently proposed three-dimensional crystal model, and calculated intensities in the equatorial region of the x-ray diffraction pattern agree with observed values.

Enhanced Hydrogen Storage Kinetics of Melt Spun Nanocrystalline and Amorphous Mg2Ni-Type Alloy by Substituting Ni with Co

2011 ◽  
Vol 399-401 ◽  
pp. 1419-1424
Author(s):  
Yang Huan Zhang ◽  
Guo Fang Zhang ◽  
Xia Li ◽  
Zhong Hui Hou ◽  
Yin Zhang ◽  
...  
Keyword(s):  
Melt Spinning ◽  
Cast Alloy ◽  
Nanocrystalline Structure ◽  
Amorphous Structure ◽  
High Rate ◽  
Desorption Kinetics ◽  
Type Alloy ◽  
Nanocrystalline And Amorphous ◽  
Rate Discharge ◽  
High Rate Discharge

The nanocrystalline and amorphous Mg2Ni1-xCox (x=0, 0.1, 0.2, 0.3, 0.4) alloys were prepared by melt-spinning technique. The structures of the alloys were studied by XRD, SEM and HRTEM. The hydrogen absorption and desorption kinetics and the high rate discharge ability (HRD) of the alloys were measured. The results show that the as-spun Co-free alloy holds a typical nanocrystalline structure, whereas the as-spun alloys containing Co display a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. The substitution of Co for Ni evidently improves the hydriding and dehydriding kinetics and the HRD of the alloys. With an increase in the amount of Co substitution from 0 to 0.4, the HRD value rises from 52.9% to 60.3% for the as-cast alloy, and from 65.9% to 76.0% for the as-spun (30 m/s) alloy.

scholarly journals Acemetacin cocrystals and salts: structure solution from powder X-ray data and form selection of the piperazine salt

IUCrJ ◽  
2014 ◽  
Vol 1 (2) ◽  
pp. 136-150 ◽  
Author(s):  
Palash Sanphui ◽  
Geetha Bolla ◽  
Ashwini Nangia ◽  
Vladimir Chernyshev
Keyword(s):  
Hydrogen Bonds ◽  
Dissolution Rate ◽  
Aqueous Medium ◽  
Acid Amide ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Reference Drug ◽  
X Ray ◽  
Time Period ◽  
Solid Form

Acemetacin (ACM) is a non-steroidal anti-inflammatory drug (NSAID), which causes reduced gastric damage compared with indomethacin. However, acemetacin has a tendency to form a less soluble hydrate in the aqueous medium. We noted difficulties in the preparation of cocrystals and salts of acemetacin by mechanochemical methods, because this drug tends to form a hydrate during any kind of solution-based processing. With the objective to discover a solid form of acemetacin that is stable in the aqueous medium, binary adducts were prepared by the melt method to avoid hydration. The coformers/salt formers reported are pyridine carboxamides [nicotinamide (NAM), isonicotinamide (INA), and picolinamide (PAM)], caprolactam (CPR),p-aminobenzoic acid (PABA), and piperazine (PPZ). The structures of an ACM–INA cocrystal and a binary adduct ACM–PABA were solved using single-crystal X-ray diffraction. Other ACM cocrystals, ACM–PAM and ACM–CPR, and the piperazine salt ACM–PPZ were solved from high-resolution powder X-ray diffraction data. The ACM–INA cocrystal is sustained by the acid...pyridine heterosynthon and N—H...O catemer hydrogen bonds involving the amide group. The acid...amide heterosynthon is present in the ACM–PAM cocrystal, while ACM–CPR contains carboxamide dimers of caprolactam along with acid–carbonyl (ACM) hydrogen bonds. The cocrystals ACM–INA, ACM–PAM and ACM–CPR are three-dimensional isostructural. The carboxyl...carboxyl synthon in ACM–PABA posed difficulty in assigning the position of the H atom, which may indicate proton disorder. In terms of stability, the salts were found to be relatively stable in pH 7 buffer medium over 24 h, but the cocrystals dissociated to give ACM hydrate during the same time period. The ACM–PPZ salt and ACM–nicotinamide cocrystal dissolve five times faster than the stable hydrate form, whereas the ACM–PABA adduct has 2.5 times faster dissolution rate. The pharmaceutically acceptable piperazine salt of acemetacin exhibits superior stability, faster dissolution rate and is able to overcome the hydration tendency of the reference drug.

Influence of Temperature on Self-Discharge and High-Rate Discharge Characteristics of La-Rich AB5-Based MH Alloy Electrode

2010 ◽  
Vol 654-656 ◽  
pp. 2835-2838 ◽  
Author(s):  
Huai Ying Zhou ◽  
Pei Pei Wang ◽  
Zhong Min Wang ◽  
Rui Ping Zou ◽  
Cheng Yuan Ni
Keyword(s):  
High Rate ◽  
Alloy Electrode ◽  
Discharge Process ◽  
Discharge Characteristics ◽  
Discharge Current Density ◽  
Influence Of Temperature ◽  
Capacity Loss ◽  
Influence Of Temperature On ◽  
Rate Discharge ◽  
High Rate Discharge

The influence of temperature on self-discharge and high-rate discharge characteristics of MmNi3.65(CoAlMn)1.35 alloy electrode has been investigated by way of simulated battery tests. Self-discharge behaviors of the MH electrode were measured using two methods: continuous mode self-discharge and step mode self-discharge. The results indicate that both reversible and irreversible capacity loss of MH electrode are mainly affected by temperature and storage time. When tested at 323K, the gross capacity loss after storage for 4 days is 30.88%, 15.02% at 273K and 20.09% at 303K, respectively. SEM analysis has shown that some needle corrosion products are formed on the surface of MH electrode, especially following storage at high temperature. The efficiency of high-rate discharge process is related closely to its discharge current density (DCD) adopted in tests, discharged capacities decreased with increasing DCD, and the electrode performed good high-rate discharge behavior at 303 K. Cyclic voltammetry (CV) analysis has indicated that near linear relationships between Ip and Scan rate (v) have been observed in the three temperature cases. The calculated values of hydrogen diffusion coefficient (D) within the electrode, are 1.479×10-8 cm2 / s at 273K, 2.437×10-8 cm2 / s at 303K, and 3.156×10-8 cm2 / s at 323K, respectively.

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