scholarly journals Effect of Concentration on the Charge Storage Kinetics of Nanostructured MnO2 Thin-Film Supercapacitors Synthesized by the Hydrothermal Method

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6124
Author(s):  
Aviraj M. Teli ◽  
Sonali A. Beknalkar ◽  
Sachin A. Pawar ◽  
Deepak P. Dubal ◽  
Tukaram D. Dongale ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Photoelectron Spectroscopy ◽  
Rate Capability ◽  
High Specific Capacitance ◽  
Charge Storage ◽  
Cyclic Voltammogram ◽  
X Ray ◽  
Diffusion Controlled ◽  
Amorphous Manganese Oxide ◽  
Kinetics Of

In this study, amorphous manganese oxide (MnO2) nanostructured thin films were synthesized by a simple hydrothermal method. It is well known that the nanostructure plays a crucial role in energy storage applications. Herein, MnO2 nanostructures ranging from plates to flakes were synthesized without the use of any hard or soft templates. The 4+ oxidation state of Mn was confirmed by X-ray photoelectron spectroscopy. The MnO2 nanoflake structure has a specific surface area of 46 m2g−1, which provides it with an excellent rate capability and an exactly rectangular cyclic voltammogram (CV) curve. The MnO2 nanoflake electrode has a high specific capacitance of about 433 Fg−1, an energy density of 60 Whkg−1 at 0.5 mAcm−2, and an excellent cyclic stability of 95% over 1000 CV cycles in 1 M aq. Na2SO4. Kinetics analysis of the charge storage in the nanoflake MnO2 sample shows a 55.6% diffusion-controlled contribution and 44.4% capacitive-controlled contribution to the total current calculated at a scan rate of 100 mVs−1 from the CV curve.

scholarly journals Boron and Nitrogen Co-Doped Porous Carbons Synthesized from Polybenzoxazines for High-Performance Supercapacitors

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 657 ◽  
Author(s):  
Bai ◽  
Ge ◽  
Bai
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Chemical Activation ◽  
Rate Capability ◽  
Weight Ratio ◽  
High Specific Capacitance ◽  
Porous Carbons ◽  
Element Analysis ◽  
X Ray ◽  
Co Doped

Boron and nitrogen co-doped porous carbons (BNPC-X) were synthesized from boron-containing polybenzoxazines through carbonization and chemical activation, where X represents the weight ratio of boric acid to benzoxazine resin. The as-prepared BNPC-X were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, element analysis and electrochemical measurements. The results show that the BNPC-0.15 possesses relatively high weight fractions of boron (2.97 wt %) and nitrogen (2.43 wt %), a homogeneous pore distribution, and remarkable electrochemical capacitive performance. It exhibits high specific capacitance (286 F·g−1 at 0.05 A·g−1), excellent rate capability (at A·g−1), and good charge–discharge stability (>92% capacitance retention after 1,000 cycles at 1.0 A·g−1) in 6 M KOH aqueous solution.

Ternary Composite of Molybdenum Disulfide-Graphene Oxide-Polyaniline for Supercapacitor

2021 ◽  
Author(s):  
Ke Qu ◽  
Yuqi Bai ◽  
Miao Deng
Keyword(s):  
Graphene Oxide ◽  
Molybdenum Disulfide ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Light Emitting Diode ◽  
Rate Capability ◽  
Energy Storage And Conversion ◽  
Carbon Paper ◽  
Power Sources ◽  
X Ray

Abstract The ever-increasing need for small and lightweight power sources for use in portable or wearable electronic devices has spurred the development of supercapacitors as a promising energy storage and conversion system. In this work, a simple, facile and easy-to-practice method has been developed to employ carbon paper (CP) as the support to coat molybdenum disulfide (MoS2) and graphene oxide (GO), followed by electrodeposition of polyaniline (PANI) to render CP/MoS2-GO-PANI. The preparation parameters, such as amounts of MoS2, GO and number of aniline electropolymerization cycles, have been optimized to render CP/MoS2-GO-PANI the best capacitive performance. The as-prepared optimal CP/MoS2-GO-PANI is characterized by X-ray powder diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. The supercapacitive properties of CP/MoS2-GO-PANI as an electrode have been evaluated electrochemically via cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy testing. CP/MoS2-GO-PANI delivers a specific capacitance of 255.1 F/g at 1.0 A/g and exhibits excellent rate capability under larger current densities. Moreover, a symmetrical supercapacitor is assembled and three are connected in series to power a light-emitting diode for ~15 minutes, demonstrating the promising application potential of CP/MoS2-GO-PANI-based supercapacitor.

High-rate capability of Na2FePO4F nanoparticles by enhancing surface carbon functionality for Na-ion batteries

2017 ◽  
Vol 5 (35) ◽  
pp. 18707-18715 ◽  
Author(s):  
Jesse S. Ko ◽  
Vicky V. T. Doan-Nguyen ◽  
Hyung-Seok Kim ◽  
Xavier Petrissans ◽  
Ryan H. DeBlock ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Rate Capability ◽  
High Rate ◽  
Charge Storage ◽  
High Rate Capability ◽  
Surface Carbon ◽  
Reduced Graphene ◽  
Kinetics Of

Na-ion charge-storage kinetics of polyol-derived Na2FePO4F are enhanced by using a nanocomposite comprising nanoparticles and reduced graphene oxide.

GROWTH OF OXIDE LAYER ON GERMANIUM (011) SUBSTRATE UNDER DRY AND WET ATMOSPHERES

1999 ◽  
Vol 06 (06) ◽  
pp. 1053-1060 ◽  
Author(s):  
N. TABET ◽  
J. AL-SADAH ◽  
M. SALIM
Keyword(s):  
Simple Model ◽  
Oxide Film ◽  
Growth Kinetics ◽  
Photoelectron Spectroscopy ◽  
Early Stage ◽  
X Ray ◽  
Apparent Thickness ◽  
Different Temperatures ◽  
Kinetics Of

X-ray Photoelectron Spectroscopy (XPS) has been used to investigate the oxidation of (011) Ge substrates. The sample surfaces were CP4-etched, then annealed in situ, at different temperatures, for various durations. Dry and wet atmospheres were used. The oxidation rate during the early stage was increased by the presence of moisture in the atmosphere. A simple model was used to define and determine an apparent thickness of the oxide film from XPS measurements. The time dependence of the apparent thickness is consistent with a partial coverage of the surface by oxide islands. The growth kinetics of the oxide islands obeys a nearly cubic law.

scholarly journals Enhanced removal of hexavalent chromium by different acid-modified biochar derived from corn straw: behavior and mechanism

2020 ◽  
Vol 81 (10) ◽  
pp. 2270-2280
Author(s):  
Yonggang Xu ◽  
Tianxia Bai ◽  
Yubo Yan ◽  
Yunfeng Zhao ◽  
Ling Yuan ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Hydrogen Ion ◽  
Corn Straw ◽  
Order Model ◽  
Freundlich Model ◽  
X Ray ◽  
Modified Biochar ◽  
Before And After ◽  
Pseudo Second Order ◽  
Kinetics Of

Abstract It is of great significance to remove Cr(VI) from water as a result of its high toxicity. Biochar from corn straw was modified by different acids (HNO3, H2SO4 and H3PO4) to remove Cr(VI) from aqueous solution. To estimate the removal mechanisms of Cr(VI) by the acid-modified biochars, batch experiments were performed in the light of contact time, Cr(VI) concentration, and pH, and the characteristics of acid-modified biochars before and after Cr(VI) adsorption were investigated by Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS). The adsorption kinetics of Cr(VI) by acid-modified biochars were consistent with the pseudo-second-order model, and the adsorption isotherm obeyed the Freundlich model. Furthermore, the acid- modified biochars could supply more oxygen-containing functional groups (-COOH and -OH) as electron donor (e−) and hydrogen ion (H+) to enhance the reduction of Cr(VI) to Cr(III), resulting in enhanced removal of Cr(VI). HNO3-modified biochar exhibited the highest removal efficiency of Cr(VI). In general, the acid modifition of biochar was an effective method to increase the removal of Cr(VI).

On the Mechanism of Milling Induced Disordering in AlFe

1996 ◽  
Vol 460 ◽  
Author(s):  
M. T. Clavaguera-Mora ◽  
J. Zhu ◽  
M. Meyer ◽  
L. Mendoza-Zelis ◽  
F. H. Sanchez ◽  
...  
Keyword(s):  
Long Range ◽  
Milling Time ◽  
Continuous Heating ◽  
X Ray Diffraction ◽  
Mechanical Grinding ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Diffusion Controlled ◽  
Transmission Mössbauer Spectroscopy ◽  
Kinetics Of

ABSTRACTThe evolution of the B2-AlFe phase during mechanical grinding in Ar has been examined as a function of milling time by X-Ray diffraction, transmission Mössbauer spectroscopy and differential scanning calorimetry. Short and long range disorder was observed to increase with the mechanical treatment up to the attainment of a steady state. The evolution of the long range order parameter and of the local atomic configurations at Fe sites were analyzed in terms of possible mechanisms for milling induced disordering. The kinetics of the thermal reordering was studied under continuous heating and isothermal calorimetrie regimes. Modeling of the reordering processes by diffusion controlled growth of pre-existing ordered grains is presented as well as the estimated values of both the enthalpy and the activation energy of the reordering process. The results are consistent with a non uniform distribution of disorder throughout the sample and will be compared with preceding information on related systems.

X-ray photoelectron spectroscopy study of the growth kinetics of biomimetically grown hydroxyapatite thin-film coatings

2010 ◽  
Vol 256 (23) ◽  
pp. 7178-7185 ◽  
Author(s):  
K. McLeod ◽  
S. Kumar ◽  
N.K. Dutta ◽  
R.St.C. Smart ◽  
N.H. Voelcker ◽  
...  
Keyword(s):  
Thin Film ◽  
Growth Kinetics ◽  
Photoelectron Spectroscopy ◽  
Spectroscopy Study ◽  
X Ray ◽  
Film Coatings ◽  
Thin Film Coatings ◽  
Kinetics Of

scholarly journals Study on the Phase Transformation Kinetics of Sol-Gel DrivedTiO2Nanoparticles

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
H. Mehranpour ◽  
M. Askari ◽  
M. Sasani Ghamsari ◽  
H. Farzalibeik
Keyword(s):  
Activation Energy ◽  
Phase Transformation ◽  
Sol Gel ◽  
Rutile Phase ◽  
Transformation Kinetics ◽  
X Ray ◽  
Prepared Nanoparticles ◽  
Phase Transformation Kinetics ◽  
Diffusion Controlled ◽  
Kinetics Of

Titanium dioxide nanopowders were synthesized by the diffusion controlled sol-gel process (LaMer model) and characterized by DTA-TG, XRD, and SEM. The preparedTiO2nanoparticles have uniform size and morphology, and the phase transformation kinetics of obtained material was studied by interpretation of the X-ray diffraction patterns peaks on the base of Avrami equation. The stating point of anatase-rutile phase transformation temperature in the prepared nanoparticles was found between 100 and200°C. A decreasing trend on the intensity of X-ray peaks of anatase phase was observed up to600°Cwhen the presence of the rutile phase became predominant. Results indicated that the transition kinetics of the diffusion controlled prepared nanoparticles was begun at low temperature, and it can be concluded that the nucleation and growth sites in these particles were more than other. However, it has been found that the nucleation activation energy of rutile phase was 20 kj/mol, and it is the lowest reported activation energy.

FERROMAGNETIC RESONANCE STUDY OF AMORPHOUS AND NANOCRYSTALLINE Fe81B13.5Si3.5C2 RIBBONS

2009 ◽  
Vol 23 (16) ◽  
pp. 3391-3402
Author(s):  
WEERAPHAT PON-ON ◽  
PONGTIP WINOTAI ◽  
I-MING TANG
Keyword(s):  
Ferromagnetic Resonance ◽  
Resonance Line ◽  
Isothermal Annealing ◽  
Amorphous Matrix ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffusion Controlled ◽  
Nano Grains ◽  
Relative Change ◽  
Kinetics Of

The nanocrystallization process in amorphous Fe 81 B 13.5 Si 3.5 C 2 ribbons caused by isothermal annealing below the crystallization temperature is studied. X-ray diffraction and Mossbauer spectroscopy measurements are used to identify the formation of new Fe containing compounds such as the ribbons annealed at various temperatures. The ferromagnetic resonance measurements for an as-cast ribbon and the 495°, 525°C and 600°C annealed ribbons exhibit a resonance line at 63.64 mT for φ = 0°. The sample annealed at 425°C shows two resonance peaks at 95.45 mT and 295.46 mT. These are due to the nanocrystalline α– Fe(Si) phase. The resonance-line widths are seen to broaden after the ribbons are annealed at 495°C and 525°C, at which time, the amorphous matrix crystallizes into nano-grains of α– Fe(Si) , t– Fe 2 B and t– Fe 3 B phases. The kinetics of the crystallization is discussed in terms of the relative change in the line width of the samples annealed at 495°C for different annealing times. These results yielded an Avrami exponent, n of 0.84 which is consistent with diffusion-controlled growth with a nucleation rate close to zero.

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