Effects of the Pre-Freezing Time on the Structures and Electrochemical Performances of Co-B Alloys

2011 ◽  
Vol 391-392 ◽  
pp. 1085-1089 ◽  
Author(s):  
Chuan Wu ◽  
Chun Hui Pang ◽  
Feng Wu ◽  
Ying Bai ◽  
Chi Chen ◽  
...  
Keyword(s):  
Cycling Performance ◽  
Area Measurement ◽  
Bet Surface Area ◽  
Electrochemical Performances ◽  
Freezing Time ◽  
Drying Method ◽  
X Ray Diffraction ◽  
Surface Area Measurement ◽  
A Current ◽  
Discharge Test

A series of Co-B alloys with uniform nanoparticles were prepared via a vacuum freeze-drying method, which the precursors of Co-B alloys were prepared by the reduction of bivalent cobalt chloride with aqueous sodium borohydride solution. The alloys were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and brunauer emmett teller (BET) surface area measurement. The electrochemical activities of Co-B samples were examined by charge-discharge test. This work studied the influence of pre-freezing time on the microstructure and electrochemical performance. The sample pre-freezing for 3 hours exhibits the best cycling performance than others, the discharge capacity increase to its maximum 438mAh/g, and it still remained 232 mAh/g after 60 cycles at a current of 50 mAh/g; while those of samples pre-freezing for 1 hour and 5 hours are 399 mAh/g and 413mAh/g, respectively.

Preparation and Electrochemical Performance of Mn3O4/GR Composites Electrode Material in Supercapacitors

2019 ◽  
Vol 807 ◽  
pp. 50-56
Author(s):  
Yun Long Zhou ◽  
Zhi Biao Hu ◽  
Li Mei Wu ◽  
Jiao Hao Wu
Keyword(s):  
Room Temperature ◽  
Raw Materials ◽  
Precipitation Method ◽  
Electrochemical Performances ◽  
Manganese Sulfate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Precipitation ◽  
A Current ◽  
Discharge Test

Using hydrated manganese sulfate and general type graphene (GR) as raw materials, Mn3O4/GR composite has been successfully prepared by the liquid phase chemical co-precipitation method at room temperature. X-ray diffraction (XRD) was used to investigate the phase structure of Mn3O4powder and Mn3O4/GR composite; The electrochemical performances of the samples were elucidated by cyclic voltammetry and galvanostatic charge-discharge test in 0.5 mol/L Na2SO4electrolyte. The results show that the Mn3O4/GR composite possesses graphene phase and good reversibility; the composite also displays a specific capacitance of 318.8 F/g at a current density of 1 A/g.

Preparation of Co-Ni Mixed Oxide/Graphene Composite and its Electrochemical Performances as Supercapacitor Material

2017 ◽  
Vol 727 ◽  
pp. 775-780 ◽  
Author(s):  
Yun Long Zhou ◽  
Chen Hao Zhao ◽  
Zhi Biao Hu ◽  
Xue Yan Huang ◽  
Kai Yu Liu ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Mixed Oxides ◽  
Electrochemical Performances ◽  
X Ray Diffraction ◽  
Galvanostatic Charge ◽  
X Ray ◽  
Graphene Composite ◽  
A Current ◽  
Charge Discharge ◽  
Discharge Test

The Co-Ni mixed oxides/graphene composite has been prepared using the solution based oxidation route. The structures of bare Co-Ni mixed oxides and Co-Ni mixed oxides/graphene composite is clearly studied by X-ray diffraction. The electrochemical properties of Co-Ni mixed oxides/graphene composite are investigated by Cyclic Voltammetry (CV) and galvanostatic charge discharge test. The result shows that, the NiO phase has not been detected in the composite, and the graphene composite delivers a discharge capacity of 353.6 F/g at a current density of 0.32 A g-1.

scholarly journals The Effect of Using H4P2O7 as Phosphorus Source for Synthesizing Vanadyl Pyrophosphate Catalysts

2017 ◽  
Vol 6 (3) ◽  
pp. 207
Author(s):  
Y.H. Taufiq-Yap ◽  
A. Raslan ◽  
R. Irmawati
Keyword(s):  
Surface Area ◽  
Area Measurement ◽  
Bet Surface Area ◽  
Vanadyl Pyrophosphate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Area Measurement ◽  
Phosphorus Source ◽  
Temperature Programmed ◽  
Two Peaks

<p>Vanadyl pyrophosphate (VO)<sub>2</sub>P<sub>2</sub>O<sub>7</sub> catalysts synthesized via VOPO<sub>4</sub>·2H<sub>2</sub>O were investigated by using BET surface area measurement, X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Temperature-Programmed Techniques (TPD and TPRS). H<sub>3</sub>PO<sub>4</sub> and H<sub>4</sub>P<sub>2</sub>O<sub>7</sub> were used as the phosphorus source. Only pyrophosphate phase was observed for both final catalysts after 75 hours of calcination in a reaction flow of <em>n</em>-butane/air mixture (0.75% <em>n</em>-butane/air). However, catalyst derived from H<sub>4</sub>P<sub>2</sub>O<sub>7</sub> based preparation (denoted VPD<sub>pyro</sub>) exhibit better crystallinity and slightly higher BET surface area compared to the H<sub>3</sub>PO<sub>4</sub> based preparation (denoted VPD<sub>ortho</sub>). The nature of the oxidants for both catalysts was investigated by O<sub>2</sub>-TPD. For VPD<sub>pyro</sub>, TPD showed an oxygen peak maximum at 986 K and a shoulder at 1003 K, whereas for VPD<sub>ortho</sub>, the oxygen was desorbed as two peaks maxima at 966 and 994 K. The total amount of oxygen desorbed thermally from VPD<sub>pyro</sub> (3.60×10<sup>20</sup> atom×g<sup>-1</sup>) is higher than that obtained for VPD<sub>ortho</sub> (3.07×10<sup>20</sup> atom×g<sup>-1</sup>). VPD<sub>pyro</sub> displayed a slightly improved activity and selectivity for <em>n</em>-butane oxidation. A proper amount of V<sup>5+</sup> species may have an effect on the enhancement of the catalytic activity.</p>

Vanadium-doped titania-pillared montmorillonite clay as a catalyst for selective catalytic reduction of NO by ammonia

Clay Minerals ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 665-672 ◽  
Author(s):  
K. Bahranowski ◽  
J. Janas ◽  
T. Machej ◽  
E. M. Serwicka ◽  
L. A. Vartikian
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Pillared Clay ◽  
Area Measurement ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Reduction Of No ◽  
Pillared Montmorillonite ◽  
Doped Titania

AbstractA series of V-doped titania-pillared clay catalysts, characterized by ICP-AES chemical analysis, X-ray diffraction, BET surface area measurement, and ESR spectroscopy, have been tested in the selective catalytic reduction of NO by NH3. An ESR analysis shows that V dopant is anchored to the titania pillars. Vanadyl species with differing degrees of in-plane V-O π-covalent bonding are produced depending on the method of sample preparation. Polymeric V species appear as the V content is increased. Catalytic performance of these systems depends on the method of preparation and on the V content. The best catalyst, converting 90-100% NO in the temperature range 523-623 K, is obtained by exchange of pillared montmorillonite with vanadyl ions, at an extent of exchange below the level where significant amounts of polymeric V species appear. The co-pillared catalyst, containing vanadyl centres characterized by a higher degree of in-plane ncovalent bonding (according to ESR), is less selective than the exchanged samples.

Fast Microwave Synthesis Lithium Vanadium Phosphate Using Peg as a Novel Carbon Source

2012 ◽  
Vol 455-456 ◽  
pp. 884-888
Author(s):  
Ji Yan ◽  
Zhi Yuan Tang ◽  
Hui Xia Ren ◽  
Li Ma
Keyword(s):  
Carbon Source ◽  
Cathode Material ◽  
Microwave Synthesis ◽  
Electrochemical Impedance ◽  
Cycling Performance ◽  
Lithium Vanadium Phosphate ◽  
X Ray Diffraction ◽  
Vanadium Phosphate ◽  
Electrochemical Tests ◽  
Discharge Test

The Li3V2(PO4)3/C cathode material is prepared by fast microwave synthesis route using PEG as carbon source. The samples were characterized by X-ray diffraction (XRD), galvanostatically charge/discharge test and electrochemical impedance spectroscopy (EIS). XRD result shows that the material was well crystallized and the structure was indexed as a monoclinic Li3V2(PO4)3/C. The electrochemical tests of material exhibit good cycling performance, which delivered a high initial discharge of 125.2 mAh g-1 at 0.2C and the retention of capacity was 92.4% after 50 cycles. From this study, the PEG-based microwave preparation method is regarded as a feasible route for the preparation of Li3V2(PO4)3/C cathode material.

Electrochemical Performance Cr Doped Spinel LiMn2O4 Cathode for Lithium Ion Batteries

2014 ◽  
Vol 636 ◽  
pp. 49-53
Author(s):  
Si Qi Wen ◽  
Liang Chao Gao ◽  
Jia Li Wang ◽  
Lei Zhang ◽  
Zhi Cheng Yang ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Lithium Ion Batteries ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Lithium Ion ◽  
Cycling Performance ◽  
Cycle Performance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Discharge Test

To improve the cycle performance of spinel LiMn2O4as the cathode of 4 V class lithium ion batteries, spinel were successfully prepared using the sol-gel method. The dependence of the physicochemical properties of the spinel LiCrxMn2-xO4(x=0,0.05,0.1,0.2,0.3,0.4) powders powder has been extensively investigated by using X-ray diffraction (XRD), scanning electron microscope (SEM), charge-discharge test and electrochemical impedance spectroscopy (EIS). The results show that as Mn is replaced by Cr, the initial capacity decreases, but the cycling performance improves due to stabilization of spinel structure. Of all, the LiCr0.2Mn1.8O4has best electrochemical performance, 107.6 mAhg-1discharge capacity, 96.1% of the retention after 50 cycles.

Synthesis, Characterization and Capacitive Behaviors of Nanoporous Carbons Obtained by Using the Template of Zeolite-13X/MCM-48 Biporous Molecular Sieve

2011 ◽  
Vol 688 ◽  
pp. 326-333
Author(s):  
Huan Xu ◽  
Qiu Ming Gao
Keyword(s):  
Molecular Sieve ◽  
Furfuryl Alcohol ◽  
Chemical Vapor ◽  
Casting Process ◽  
Cycling Performance ◽  
Electrochemical Performances ◽  
X Ray Diffraction ◽  
Nanoporous Carbons ◽  
Zeolite 13X ◽  
Transmission Electron

Zeolite-13X/MCM-48 biporous molecular sieve has been synthesized in the mode of overgrowth of MCM-48 on the surface of pre-added zeolite 13X. This kind of biporous molecular sieve has been taken as the template to prepare nanoporous carbons by a two-step casting process with furfuryl alcohol and acetonitrile as the precursors. The structures and textures are characterized by X-ray diffraction, nitrogen sorption at 77 K and high-resolution transmission electron microcopy. The electrochemical performances of the as-prepared porous carbons were tested by cyclic voltammetry and galvanostatic charge-discharge cycling in aqueous electrolyte. One of the carbon samples (labeled as C3-3) which is prepared by adding 5% zeolite-13X in the MCM-48 sol as the template and conducting acetonitrile chemical vapor deposition for 4 h after the impregnation of furfuryl alcohol. The C3-3 nanoporous carbon keeps the structure ordering and has the capacitance of 197 F g-1 at 2 mV s-1. The cycling performance of this carbon sample is excellent, which can maintain above 90% capacitance after 1000 cycles at 1 A g-1.

Characterization of Nanosilica of Tapioca Peel as Adsorbent for Biomethane Storage System

2015 ◽  
Vol 1125 ◽  
pp. 266-270
Author(s):  
Hasnizah binti Habibun ◽  
Shareena Fairuz binti Abdul Manaf ◽  
Nur Hashimah Alias ◽  
Nur Shahidah Ab Aziz ◽  
Fazlena Hamzah
Keyword(s):  
Physical Properties ◽  
Metal Oxides ◽  
Surface Area ◽  
Storage System ◽  
Physical Structure ◽  
Area Measurement ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Adsorption And Desorption ◽  
Adsorption And Desorption Performance

Biomethane is an alternative and renewable source that occurred naturally which produced from the anaerobic digestion of organic matter. It can be used as the electricity power generation, water heating and also vehicle fuel. In this study, the characteristics of the nanosilica of the tapioca peel as an adsorbent on the structural and physical properties to store the biomethane were investigated. To enhance the adsorption and desorption performance as well as the structural and physical properties, the nanosilica was modified with the metal oxides. The metal oxides that have been used to modify the nanosilica adsorbent are zinc (II) oxide (ZnO) and nickel (II) oxide (NiO). Both of the modified and unmodified nanosilica structural properties were characterized by using X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). While, the physical properties of both of the modified and unmodified nanosilica were characterized by using Brunauer, Emmet, Teller (BET) surface area measurement. The effects of both types of metal oxides with different concentration were investigated. Based on the results obtained, the structural and physical characteristics of the nanosilica were affected by the different metal oxides loading. It have been identified that 1% ZnO modified nanosilica has highest BET surface area (8.32 m2/g) with pore volume (19.23 cc/g) and pore size (82.8 nm). Thus, it concluded that 1% ZnO modified nanosilica improved the structural and physical structure. Hence, it enhances the capacity of methane adsorption and desorption prior to storage system.

scholarly journals The Improved Photocatalytic Properties of Methylene Blue for V2O3/CNT/TiO2Composite under Visible Light

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Ming-Liang Chen ◽  
Won-Chun Oh
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Photocatalytic Degradation ◽  
Area Measurement ◽  
Bet Surface Area ◽  
Multiwall Carbon Nanotube ◽  
X Ray Diffraction ◽  
Vanadyl Acetylacetonate ◽  
X Ray ◽  
Transmission Electron

Multiwall carbon nanotube (MWCNT), vanadyl acetylacetonate (V(acac)3), and titaniumn-butoxide (TNB) were used as carbon, vanadium oxide, and titanium oxide precursor to prepare V2O3/CNT/TiO2composite. The obtained composite was characterized by BET surface area measurement, X-ray diffraction, transmission electron microscopy, and energy dispersive X-ray analysis. In addition, we used methylene blue (MB) solution under condition of visible light irradiation to determine their photocatalytic degradation efficiency. In conclusion, the V2O3/CNT/TiO2composite had excellent photocatalytic degradation for MB solution under visible light.

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