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Wenjiang Ding - One of the best experts on this subject based on the ideXlab platform.
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Hydrogen storage and hydrolysis properties of core-shell structured Mg-MFx (M=V, Ni, La and Ce) nano-composites prepared by arc Plasma Method
Journal of Power Sources, 2017Co-Authors: Jianfeng Mao, Jianxin Zou, Xiaoqin Zeng, Wenjiang DingAbstract:Abstract In this work, core-shell structured Mg-MF x (M = V, Ni, La and Ce) nano-composites are prepared by using arc Plasma Method. The particle size distribution, phase components, microstructures, hydrogen sorption properties of these composites and hydrolysis properties of their corresponding hydrogenated powders are carefully investigated. It is shown that the addition of MF x through arc Plasma Method can improve both the hydrogen absorption kinetics of Mg and the hydrolysis properties of corresponding hydrogenated powders. Among them, the Mg-NiF 2 composite shows the best hydrogen absorption properties at relatively low temperatures, which can absorb 3.26 wt% of H 2 at 373 K in 2 h. Such rapid hydrogen absorption rate is mainly due to the formation of Mg 2 Ni and MgF 2 on Mg particles during arc evaporation and condensation. In contrast, measurements also show that the hydrogenated Mg-VF 3 composite has the lowest peak desorption temperature and the fastest hydrolysis rate among all the hydrogenated Mg-MF x composites. The less agglomeration tendency of Mg particles and VO 2 covered on MgH 2 particles account for the reduced hydrogen desorption temperature and enhanced hydrolysis rate.
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Hydrogen storage properties of Mg–TiO2 composite powder prepared by arc Plasma Method
Transactions of Nonferrous Metals Society of China, 2014Co-Authors: Yin-cheng Pan, Jianxin Zou, Xiaoqin Zeng, Wenjiang DingAbstract:Abstract Mg-based Mg–TiO2 composite powder was prepared by arc Plasma evaporation of the Mg+5%TiO2 mixture followed by passivation in air. ICP, XRD and SEM techniques were used to characterize the composition, phase components and microstructure of the composite powder. The hydrogen sorption properties of the composite powder were investigated by DSC and PCT techniques. According to the data from PCT measurements, the hydrogenation enthalpy and entropy changes of the composite powder are calculated to be −71.5 kJ/mol and −130.1 J/(K·mol), respectively. Besides, the hydrogenation activation energy is determined to be 77.2 kJ/mol. The results indicate that TiO2 added into Mg by arc Plasma Method can act as a catalyst to improve the hydrogen sorption kinetic properties of Mg.
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A comparison study of Mg–Y2O3 and Mg–Y hydrogen storage composite powders prepared through arc Plasma Method
Journal of Alloys and Compounds, 2014Co-Authors: Sheng Long, Jianxin Zou, Xiaoqin Zeng, Xi Chen, Wenjiang DingAbstract:Abstract In this study, two Mg based hydrogen storage composite powders, Mg–Y 2 O 3 and Mg–Y, were prepared through arc Plasma Method followed by in situ passivation. The composition, phase component, and hydrogen storage properties of the two powders were analyzed by using ICP, XRD, PCT and DTA techniques. ICP analyses revealed a reduction in Y content of both powders when compared to their initial composition, especially for the Mg–Y powder (from 25 wt% down to 0.58 wt%). XRD results showed the presence of Y 2 O 3 both in the Mg–Y 2 O 3 and the Mg–Y powders. PCT analyses showed that the hydrogen storage capacity of the Mg–Y 2 O 3 powder is higher than that of the Mg–Y powder. Based on van’t Hoff equation, the hydrogenation enthalpies of the Mg–Y 2 O 3 and Mg–Y powders are determined to be −75.4 and −71.8 kJ/mol H 2 , respectively. DTA measurements showed that the onset dehydriding temperature of the hydrogenated Mg–Y 2 O 3 powder is lower than that of the hydrogenated Mg–Y powder. The above results indicated that Y 2 O 3 has a good catalytic effect on the hydrogen sorption in Mg and the effect can be better achieved in the arc evaporated Mg–Y 2 O 3 composite powder.
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study on the hydrogen storage properties of core shell structured mg re re nd gd er nano composites synthesized through arc Plasma Method
International Journal of Hydrogen Energy, 2013Co-Authors: Xiaoqin Zeng, Xi Chen, Yanjun Ying, Si Zhou, Wenjiang DingAbstract:Abstract Mg based Mg–Rare earth (RE) hydrogen storage nano-composites were prepared through an arc Plasma Method and their composition, phase components, microstructure and hydrogen sorption properties were carefully investigated. It is shown that the Mg–RE composites have special metal-oxide type core–shell structure, that is, ultrafine Mg(RE) particles are covered by nano-sized MgO and RE 2 O 3 . In comparison to pure Mg powders prepared using the same Method, the hydrogen absorption kinetics can be significantly improved through minor addition of RE to Mg. In addition, the Mg–RE composite powders show better anti-oxidation ability than pure Mg powders, resulting in the increased hydrogen storage capacity of Mg–RE powders over pure Mg powders. In particular, the hydrogenation enthalpy can be increased and the dehydriding temperature can be reduced through minor addition of Er. The experimental results show that both the RE in solid solution state in Mg and the RE 2 O 3 nano-grains covered on Mg particles contribute to the improved hydrogen storage thermodynamic, kinetic and anti-oxidation properties of Mg ultrafine particles.
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Hydrogen storage properties of a Mg–Ce oxide nano-composite prepared through arc Plasma Method
Journal of Alloys and Compounds, 2013Co-Authors: Sheng Long, Jianxin Zou, Xiaoqin Zeng, Yana Liu, Wenjiang DingAbstract:Abstract Mg based Mg–Ce oxide nano-composite powders were prepared through arc Plasma evaporation of Mg–5 wt.%CeO2 mixture followed by passivation in air. ICP, XRD, TEM and PCT techniques were used to characterize the composition, phase components, microstructure and hydrogen sorption properties of the composite. It is shown that CeO2 transformed into Ce2O3 after arc evaporation and nanoscale Ce2O3 particles are attached on the surface of Mg particles, forming a core–shell structured metal-oxide nano-composite. The hydrogenation and dehydrogenation enthalpies of the composite are calculated to be −71 kJ/mol H2 and 75.41 kJ/mol H2, respectively, while the activation energy for hydrogen absorption is 47.75 kJ/mol H2. In addition, the composite can absorb 4.07 wt.% of hydrogen at 323 K in 10 h. These results revealed that the minor addition of Ce oxide in Mg through arc Plasma Method is able to improve significantly the hydrogen absorption kinetics of Mg.
S. Roth - One of the best experts on this subject based on the ideXlab platform.
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2-D localization in single wall carbon nanotube network synthesized by arc-Plasma Method
Synthetic Metals, 1999Co-Authors: Gyu-tae Kim, Jin Gyu Park, Y.w. Park, Kun Liu, G. Düsberg, S. RothAbstract:Abstract Resistivity ρ(T) and magnetoresistance (MR), ((ρ(H)-ρ(H=0))/ρ(H=0), of the entangled single wall carbon nanotube (SWCN) network are studied. The temperature dependence of the resistivity shows the negative dρ/dT from T=4.2K to 300K, which fits well to the 2-dimensional variable range hopping (VRH) (ρ(T)=ρ 0 exp((T 0 /T) 1/3 )) formula with T 0 = 259.2 K. The overall MR shows a negative H 2 behavior at low magnetic field. At T≤3.8K and high magnetic field, the negative MR turns to be positive. The positive MR becomes saturating for H>10 Tesla. The negative MR with a positive upturn can be decomposed into a positive contribution from the 2-dimensional spin-dependent VRH and a negative contribution from the 2-dimensional weak localization (WL). Moreover we report the interesting chain-like ring structures found from the by-products of SWCNs synthesized by the arc-Plasma Method.
A. Anukaliani - One of the best experts on this subject based on the ideXlab platform.
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Characterization of undoped and Co doped ZnO nanoparticles synthesized by DC thermal Plasma Method
Physica B: Condensed Matter, 2011Co-Authors: M. Nirmala, A. AnukalianiAbstract:Abstract ZnO nanopowders doped with 5 and 10 at% cobalt were synthesized and their antibacterial activity was studied. Cobalt doped ZnO powders were prepared using dc thermal Plasma Method. Crystal structure and grain size of the particles were characterized by X-ray diffractometry and optical properties were studied using UV–vis spectroscopy. The particle size and morphology was observed by SEM and HRTEM, revealing rod like morphology. The antibacterial activity of undoped ZnO and cobalt doped ZnO nanoparticles against a Gram-negative bacterium Escherichia coli and a Gram-positive bacterium Bacillus atrophaeus was investigated. Undoped ZnO and cobalt doped ZnO exhibited antibacterial activity against both E. coli and Staphylococcus aureus but it was considerably more effective in the cobalt doped ZnO.
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Optical and electrical properties of undoped and (Mn, Co) co-doped ZnO nanoparticles synthesized by DC thermal Plasma Method
Superlattices and Microstructures, 2011Co-Authors: M. Nirmala, P. Smitha, A. AnukalianiAbstract:Abstract The undoped and (Mn, Co) co-doped ZnO nanopowders were synthesized through DC thermal Plasma Method. The pellets of this powder were annealed at 450, 550 and 650 °C for 1 h. Structural, chemical and optical properties of the samples were studied by XRD, SEM, EDX, UV–Vis and PL analysis. XRD spectra showed that all the samples were hexagonal wurtzite structure and as the annealing temperature increases the material becomes purer and more crystalline. It is seen that the optical band gap decreases when the ZnO is doped with manganese and cobalt. Photoluminescence intensity varies with doping because of the increment of oxygen vacancies. DC conductivity studies of the pellets were carried out at different temperatures (25–100 °C) and it was found that the activation energy for the electrical transport is high for (Mn, Co) co-doped ZnO than undoped ZnO.
Benny Selle - One of the best experts on this subject based on the ideXlab platform.
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bonding configuration and density of defects of sioxhy thin films deposited by the electron cyclotron resonance Plasma Method
Journal of Applied Physics, 2003Co-Authors: San E Andres, G Gonzalezdiaz, F J Lopez, I. Martil, Jörg Röhrich, Wolfgang Bohne, A. Prado, D. Bravo, M Fernandez, Benny SelleAbstract:The composition, bonding configuration, hydrogen content, and paramagnetic defects of SiOxHy thin films were studied. Films were deposited by the electron cyclotron resonance Plasma Method at room temperature using SiH4 and O2 as precursor gases. The film composition was measured by heavy ion elastic recoil detection analysis and energy dispersive x-ray spectroscopy. Suboxide films with compositions ranging from SiO2 to SiH0.38 were obtained. Infrared spectroscopy showed the presence of different Si–O and Si–H vibration modes. The usual estimation of the oxygen to silicon ratio by the wave number of the Si–O–Si stretching band was not accurate for films far from stoichiometry. These off-stoichiometric films also showed a broader Si–O–Si stretching peak than the stoichiometric ones, indicating a higher bonding disorder. The position of the Si–O–Si bending and rocking modes did not depend on the film composition. On the other hand, the peak position of the Si–H modes were found strongly dependent on the Si ...
Ji Liang - One of the best experts on this subject based on the ideXlab platform.
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Investigation of carbon nanotube deposits and their formation conditions by an arc-Plasma Method in water
Nanotechnology, 2004Co-Authors: Yuan Yao, Rui Wang, Da Zhong Wei, Ji LiangAbstract:In a DC arc-Plasma Method, in deionized water, used to synthesize multi-walled carbon nanotubes (MWCNTs), hard deposits collected on the surface of the cathode are the main product rich in MWCNTs and they are easier to collect than the products collected in water. The top surface of the deposit bestrewed with column-shaped clumps also gives a hint as to potential applications of the field emission. In order to increase the yield of the deposits on the cathode surface, different parameters are used to investigate their formation. An auto-formed chamber between two electrodes during the arc discharge is found to have a determining effect on the formation of deposits on the cathode surface. Deposits are examined using SEM and TEM to investigate their structure and the CNTs in them.