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Thị Trấn Na Sầm, Vietnam

Vu T.H.T.,Key Laboratory for Petrochemical and Refinery Technologies | Tran T.T.T.,Key Laboratory for Petrochemical and Refinery Technologies | Le H.N.T.,Key Laboratory for Petrochemical and Refinery Technologies | Tran L.T.,Key Laboratory for Petrochemical and Refinery Technologies | And 3 more authors.
Electrochimica Acta | Year: 2015

In this work, Pt-SiO2/graphene nanocomposites have been synthesized under solvothermal conditions and investigated as electrocatalysts for methanol oxidation. Structure and morphology of these catalysts are characterized by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and nitrogen adsorption/desorption studies. The Pt and SiO2 contents of these nanocomposites are determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Their electrocatalytic properties are investigated by cyclic voltammetry, chronoamperometry, chronopotentiometry and electrochemical impendence spectroscopy. The as-prepared nanocomposites show the improved catalytic performance, better stability and good antiposoining ability compared with Pt supported on graphene catalyst. Particularly, the catalyst containing 9.24% of SiO2 exhibits the best electrocatalytic performance for methanol oxidation with mass activity of 1047 mA mg-1. © 2015 Elsevier Ltd. All rights reserved.

Zamfir M.R.,Sungkyunkwan University | Nguyen H.T.,Sungkyunkwan University | Nguyen H.T.,Institute of Chemistry and Materials Science | Moyen E.,Sungkyunkwan University | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

After more than 20 years of steady progress, lithium-ion batteries still exhibit modest energy capacities that seem to have reached their asymptotic values with the present combination of graphite at the anode and insertion oxide or phosphate materials at the cathode. New applications, particularly for all-electric vehicles are pushing the development of electrode materials with higher Li storage capabilities, for both electrodes. Silicon, which exhibits the highest known Li-alloying capacity is one of the most promising anode materials. However, Li alloying with Si is accompanied by a large volume change which induces cracking and rapid pulverization of Si-based anodes. Significant improvements in the anode's lifetime as well as charge-discharge rates have been obtained over the past few years by employing Si nanostructures, particularly nanowires. In this paper, we present the main synthesis methods for Si nanowires as well as the alloying properties of Li with Si and review how the use of Si-based nanowires has evolved, thanks to sophisticated material/structure combinations, including core-shell nanowires, composites as well as hollowed nanotube-like approaches. © 2013 The Royal Society of Chemistry.

Nam N.D.,PetroVietnam University | Vaka M.,Deakin University | Tran Hung N.,Institute of Chemistry and Materials Science
Journal of Power Sources | Year: 2014

To gain high hardness, good thermal stability and corrosion resistance, multicomponent TiAlSiN coating has been developed using different deposition methods. In this study, the influence of Al and Si on the electrochemical properties of TiN-coated 316L stainless steel as bipolar plate (BP) materials has been investigated in simulated proton exchange membrane fuel cell environment. The deposited TiN, TiAlN and TiAlSiN possess high hardness of 23.9, 31.7, 35.0 GPa, respectively. The coating performance of the TiN coating is enhanced by Al and Si addition due to lower corrosion current density and higher Rcoating and Rct values. This result could be attributed to the formation of crystalline-refined TiN(200), which improves the surface roughness, surface resistance, corrosion performance, and decreased passive current density. © 2014 Elsevier B.V. All rights reserved.

Nguyen H.T.,Sungkyunkwan University | Nguyen H.T.,Institute of Chemistry and Materials Science | Zamfir M.R.,Sungkyunkwan University | Duong L.D.,Sungkyunkwan University | And 3 more authors.
Journal of Materials Chemistry | Year: 2012

Amongst other requirements, a good anode for Li-ion battery applications must exhibit dimensional stability upon Li insertion, as well as chemical inertness with respect to the electrolyte. This latter characteristic is usually provided by the so-called solid electrolyte interphase (SEI), a passivating film that is formed at the end of the first lithiation step, originating from the partial reduction of the electrolyte and Li salt. However, silicon, which exhibits the highest known capacity for Li alloying, possesses none of the above attributes when used as an anode material. Actually, the large volume expansion of Si upon alloying with Li induces a mechanical instability of the SEI film, which therefore fails to provide its protective role. In this paper, we have studied the effect of thin alumina deposits on top of Si-based nanowires. A thin alumina deposit will act as a substitute for the SEI, preventing electrolyte decomposition. We observe that even if alumina films crack during lithiation-delithiation steps of the Si-based nanowires, they still provide some kind of protection, prolonging the lifetime of the anode. Using Al 2O3-coated Si-based nanowires, we have been able to obtain a lifetime of 1280 cycles when the capacity of the anode was limited to 1200 mA h g-1. We also show that uncoated Si nanowires degrade more rapidly when cycled under identical conditions. © The Royal Society of Chemistry 2012.

Khue D.N.,Institute of Chemistry and Materials Science | Chat N.V.,Institute of Chemistry and Materials Science | Minh D.B.,Institute of Chemistry and Materials Science | Lam T.D.,Vietnam Academy of Science and Technology | And 2 more authors.
Materials Science and Engineering C | Year: 2013

Comparison was observed for degradation and mineralization of the explosive 2,4,6-trinitroresorcine (TNR) in different photochemical systems TNR/UV, TNR/UV/TiO2, TNR/UV/H2O2, TNR/UV/O3, TNR/UV/TiO2/H2O2 and TNR/UV/TiO 2/O3 using High Performance Liquid Chromatography coupled with Mass Spectrometry (HPLC/MS) and Total Organic Carbon (TOC) analysis. Addition of oxidizing agents such as H2O2 or O3 accelerated the rate of TNR conversion and mineralization. Highest reaction rate was obtained in TNR/UV/TiO2/H2O2 system. The intermediate products were characterized and identified by LS-MS technique. The similarity in intermediate products of TNR suggested the analogous reaction pathways of the TNR degradation by these different systems. © 2013 Elsevier B.V.

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