scholarly journals Low Temperature Synthesis of MnO2/Graphene Nanocomposites for Supercapacitors

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Hao Huang ◽  
Guangren Sun ◽  
Jie Hu ◽  
Tifeng Jiao
Keyword(s):  
Electron Microscopy ◽  
Specific Capacitance ◽  
Electrochemical Impedance ◽  
Composite Electrodes ◽  
X Ray Diffraction ◽  
Graphene Nanocomposites ◽  
Long Cycle Life ◽  
Transmission Electron ◽  
Capacitive Properties ◽  
Lower Temperature

MnO2/graphene nanocomposites were synthesized through a simple route in a water-reflux condenser system. The as-prepared composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman microscope, and Brunauer-Emmett-Teller surface area analysis. Capacitive properties of the synthesized composite electrodes were investigated via cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectrometry in a 0.5 M Na2SO4electrolyte. Results show that this method can control the morphology and structure of MnO2loaded onto the graphene sheets. Because excessive MnO2enwrapping graphene would affect the overall conductivity, the composite prepared by lower temperature has better characteristics of supercapacitor. 60-MnO2/graphene composite (48 wt% MnO2) displays the specific capacitance as high as 350 F/g at 1000 mA/g, which is higher than that of 100-MnO2/graphene (302 F/g), and it is almost two times higher than that of MnO2(163 F/g). Furthermore, the composite exhibits excellent long cycle life along with ~93% specific capacitance retained after 5000 cycle tests.

scholarly journals Substitution of Acetylene Black by Using Modified Flake Graphite Applied in Activated Carbon Supercapacitors

2018 ◽  
Vol 160 ◽  
pp. 03005
Author(s):  
Peng Zhao ◽  
Chunmei He ◽  
Wencheng Hu
Keyword(s):  
Electron Microscopy ◽  
Activated Carbon ◽  
Electrochemical Impedance ◽  
Normal Pressure ◽  
Acetylene Black ◽  
Flake Graphite ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Capacitive Properties ◽  
Methyl Pyrrolidone

Flake graphite was mechanically modified at different times in N-methyl pyrrolidone under normal pressure. The results of the scanning electron microscopy, X-ray diffraction, and transmission electron microscopy suggested that the structure of the flake graphite was modified. The crystallinity of the flake graphite, and many defects were introduced into the material. The evaluation of capacitor performance by cyclic voltammetry, galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy was also performed. Results showed that the electrochemical performance of flake graphite was strongly enhanced, particularly when it was exfoliated for 6 h. Moreover, the electrochemical capacitive properties of activated carbon were obviously enhanced through the substitution of acetylene black by flake graphite modified for 6 h.

Few-Layered MoS2 Nanostructures for Highly Efficient Visible Light Photocatalysis

NANO ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. 1650114 ◽  
Author(s):  
Dan Li ◽  
Jianwei Li ◽  
Caiqin Han ◽  
Xinsheng Zhao ◽  
Haipeng Chu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Electrochemical Impedance ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
Electrochemical Impedance Spectra ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Hole Pair

Few-layered MoS2 nanostructures were successfully synthesized by a simple hydrothermal method without the addition of any catalysts or surfactants. Their morphology, structure and photocatalytic activity were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, electrochemical impedance spectra and UV-Vis absorption spectroscopy, respectively. These results show that the MoS2 nanostructures synthesized at 180[Formula: see text]C exhibit an optimal visible light photocatalytic activity (99%) in the degradation of Rhodamine B owing to the relatively easier adsorption of pollutants, higher visible light absorption and lower electron–hole pair recombination.

Preparation and Properties of TiO2(B)/Graphene Nanocomposites as Anode Materials Fo Lithium-Ion Batteries

2014 ◽  
Vol 875-877 ◽  
pp. 183-186 ◽  
Author(s):  
Yi Ping Tang ◽  
Shi Ming Wang ◽  
Jia Feng Ding ◽  
Guang Ya Hou ◽  
Guo Qu Zheng
Keyword(s):  
Electron Microscopy ◽  
Electrochemical Performance ◽  
Anode Materials ◽  
Graphene Nanosheets ◽  
Coulombic Efficiency ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
Graphene Nanocomposites ◽  
Transmission Electron ◽  
Uniform Diameter

In this work, TiO2(B) nanotubes with uniform diameter were prepared by the simple route of hydrothermal synthesis, and graphene nanosheets were added to form TiO2(B)/graphene nanocomposites, the two kinds of materials were comparatively studied as anode materials. The morphology and crystal structure were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The electrochemical performance was evaluated by galvanostatic chargedischarge tests. The results show that the nanocomposite electrode material has good electrochemical performance due to the contributions of graphene. At the current density of 50mA/g, the capacity of TiO2(B)/graphene is 135.8 mAh/g, and the coulombic efficiency is 61.8%, after 10 charge-discharge cycles it still retains 113.2mAh/g . However, TiO2(B) anode reduces rapidly to 65.6 mAh/g.

Laccase Biosensor Based on Ag-Doped TiO2 Nanoparticles on CuCNFs for the Determination of Hydroquinone

NANO ◽  
2016 ◽  
Vol 11 (12) ◽  
pp. 1650132 ◽  
Author(s):  
Jie Yang ◽  
Dawei Li ◽  
Zengyuan Pang ◽  
Qufu Wei
Keyword(s):  
Electron Microscopy ◽  
Storage Stability ◽  
Electrochemical Impedance ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
New Material ◽  
And Storage

A novel nanomaterial composed of copper and carbon nanofibers (CuCNFs) decorated with Ag-doped TiO2 (Ag–TiO[Formula: see text] nanoparticles was prepared through electrospinning, carbonization and solvothermal treatment. The composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS). The obtained composites were mixed with laccase and Nafion to construct novel hydroquinone biosensor. The electrochemical behavior of the novel biosensor was studied using cyclic voltammetry (CV) and chronoamperometry. The results demonstrated that the biosensor possessed a wide detection linear range (1.20–176.50[Formula: see text][Formula: see text]M), a good selectivity, repeatability, reproducibility and storage stability. This work provides a new material to design more efficient laccase (Lac) based biosensor for hydroquinone detection.

CuWO4 Nanoparticles: Investigation of Dielectric, Electrochemical Behaviour and Photodegradation of Pharmaceutical Waste

2019 ◽  
Vol 19 (11) ◽  
pp. 7026-7034 ◽  
Author(s):  
M. Thiruppathi ◽  
M. Vahini ◽  
P. Devendran ◽  
M. Arunpandian ◽  
K. Selvakumar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Electrochemical Impedance ◽  
Electrochemical Behaviour ◽  
Diclofenac Sodium ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Transmission Electron ◽  
Pharmaceutical Waste

The hydrothermally synthesized CuWO4 nanoparticles (NPs) were characterized with different analysis such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), Energy Dispersive X-ray Spectroscopy (EDX), Cyclic Voltammetry (CV), UV-Visible and Photoluminescence (PL) analysis. The prepared CuWO4 NPs were examined with Electrochemical Impedance Spectroscopy (EIS). SEM images show that CuWO4 NPs are highly spherical shaped morphology and porous in nature. The optical band gap of prepared CuWO4 NPs is found to be 2.12 eV. Photodegradation of diclofenac sodium (DFS) (medical waste) in the aqueous medium with CuWO4 NPs under visible light irradiation shows 98% degradation. The CuWO4 NPs was stable up to 5th cycle it can be used as a reusable photocatalyst for the DFS degradation. The electrical conductivity and dielectric properties of the CuWO4 NPs at room temperature is analyzed by EIS studies. The bulk conductivity value of the prepared nanoparticles is 1.477×10-5 S/cm at room temperature. The conductivity of CuWO4 NPs is found to be due to electrons movement. The CuWO4 NPs shows higher photocatalytic and electrocatalytic activity for decomposition of DFS and methanol electro-oxidation in alkaline medium respectively.

scholarly journals Alignment ofTiO2(Anatase) Crystal of Dye-Sensitized Solar Cells by External Magnetic Field

2013 ◽  
Vol 2013 ◽  
pp. 1-6
Author(s):  
Na-Yeong Hong ◽  
Hyunwoong Seo ◽  
Min-Kyu Son ◽  
Soo-Kyoung Kim ◽  
Song-Yi Park ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Electrochemical Impedance ◽  
Dye Sensitized Solar Cells ◽  
Energy Conversion Efficiency ◽  
X Ray Diffraction ◽  
Solar Simulator ◽  
Dye Sensitized ◽  
Transmission Electron ◽  
The Magnetic Field

In this study, magnetic field (B) was applied on TiO2(anatase) of dye-sensitized solar cell (DSC) for alignment of crystal. Magnetic field was applied on TiO2when deposited TiO2on the fluorine tin oxide (FTO) was dried at 373 K for crystalline orientation. And applying time ofBwas varied 0~25 min. Characteristics of the magnetic field applied TiO2films were analyzed by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). Current-voltage characteristics were also analyzed using solar simulator, and it was confirmed that the energy conversion efficiency of 41% was increased. Finally, it was identified that the magnetic field affected orientation of TiO2, resulting in the enhancement of the performance of the DSC.

Preparation of Nickel and Manganese Dioxide by Co-Precipitation and its Electrochemical Capacitive Properties

2015 ◽  
Vol 814 ◽  
pp. 86-90
Author(s):  
Qian Qian Li ◽  
Run Hua Fan ◽  
Yu Jun Bai ◽  
Chuan Bing Cheng ◽  
Gui Fang Liu ◽  
...  
Keyword(s):  
Specific Capacitance ◽  
Manganese Oxides ◽  
Electrochemical Impedance ◽  
Spherical Particles ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Capacitive Properties ◽  
Co Precipitation ◽  
Redox Capacitance

The precursor nickel and manganese carbonates were synthesized by co-precipitation with sodium carbonate as precipitant, and then nickel and manganese oxides were gained after calcination. The phase and morphology of the synthesized product were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the electrochemical characterization was performed using cyclic voltammetry (CV), galvanostatic charge–discharge tests (GCD) and electrochemical impedance spectroscopy (EIS) in a 6mol/L KOH aqueous solution electrolyte. The result showed that the products were the mixture of nickel and manganese oxides and solid solution. nanoparticles and spherical particles were gained by controlling the molar ratio of nickel and manganese. All of the samples exhibited typical Faradic redox capacitance. The specific capacitance was different with the change of nickel and manganese molar ratio. The specific capacitance (Cs) reached 130F/g at 1A/g when the ratio was 2:1.

scholarly journals Photocatalytic Reduction of CO2Using TiO2-Graphene Nanocomposites

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Jinghua Liu ◽  
Yinghua Niu ◽  
Xiong He ◽  
Jingyao Qi ◽  
Xin Li
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Chemical Method ◽  
X Ray Diffraction ◽  
Graphene Nanocomposites ◽  
X Ray ◽  
Transmission Electron ◽  
Simple Chemical ◽  
Adsorption Desorption

TiO2-graphene (TiO2-RGO) nanocomposites were preparedviaa simple chemical method by using graphene oxide (GO) and TiO2nanoparticles as starting materials. The morphologies and structural properties of the as-prepared composites were characterized by X-ray diffraction, Raman spectroscopy, N2adsorption-desorption measurements, and transmission electron microscopy. TiO2-RGO nanocomposites exhibited great photocatalytic activity toward reduction of CO2into CH4(2.10 μmol g−1 h−1) and CH3OH (2.20 μmol g−1 h−1), which is attributed to the synergistic effect between TiO2and graphene.

PREPARATION AND CHARACTERIZATION OF A POLY(PYRROLYL METHANE)/MULTIWALLED CARBON NANOTUBES COMPOSITES

NANO ◽  
2013 ◽  
Vol 08 (06) ◽  
pp. 1350063
Author(s):  
JINXIAN LIN ◽  
PAN WANG ◽  
YUYING ZHENG
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Electrode System ◽  
X Ray Diffraction ◽  
Multiwalled Carbon ◽  
Transfer Resistance ◽  
Transmission Electron

A poly(pyrrolyl methane) (Poly[pyrrole-2, 5-diyl(4-methoxybenzylidane)], PPDMOBA)/multiwalled carbon nanotubes (MWNTs) composites are fabricated by in situ chemical polycondensation of pyrrole and 4-methoxybenzaldehyde on MWNTs. The structure, morphology, thermal stability and electrical property of the resulting composites are investigated via fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and a four-probe method. The electrochemical performance of the composites is determined in a three-electrode system using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. FTIR, FESEM and TEM confirm that the composites have been successfully prepared, and PPDMOBA is uniformly dispersed in MWNTs. Electrical conductivity of PPDMOBA/MWNTs composites is 1.39 S cm-1, which is significantly larger than that of pristine PPDMOBA. The specific capacitance and charge transfer resistance of the composites is 56 F g-1 (1 mA cm-2) and 0.3Ω, respectively.

Synthesis and Densification of Nanometric Ce0.8Sm0.2O1.9-δ

2006 ◽  
Vol 972 ◽  
Author(s):  
Vincenzo Esposito ◽  
Marco Fronzi ◽  
Enrico Traversa
Keyword(s):  
Electron Microscopy ◽  
Liquid Phase ◽  
Electrochemical Impedance ◽  
Liquid Phase Sintering ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Conventional Sintering ◽  
Eis Measurements ◽  
Co Precipitation

AbstractNanometric 20% molar Sm-doped ceria (SDC20) powders were synthesized by tetrametylethylen ammine (TMDA) co-precipitation method. SDC20 was sintered in several conditions to control the final microstructure. Fast firing and conventional sintering were performed. LiNO3was used as an additive to promote liquid phase sintering of ceria at low temperatures (900-1200°C). Powders and dense pellets were analysed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy (EIS) measurements were performed on dense pellets in air to estimate the contribution of grain boundary and bulk to the electrical conductivity. Liquid phase sintering produced the densest samples with the highest conductivity.

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