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ABSTRACT: a b s t r a c t One of the biggest challenges of 21st century is to develop power-ful electrochemical energy devices (EEDs). The EEDs such as fuel cells, supercapacitors, and Li-ion batteries are among the most promising candidates in terms of power-densities and energy-den-sities. The nanostructured materials (NSMs) have drawn intense attention to develop highly efficient EEDs because of their high sur-face area, novel size effects, significantly enhanced kinetics, and so on. In this review article, we briefly introduce general synthesis, fabrication and their classification as zero-dimensional (0D), one dimensional (1D), two-dimensional (2D) and three-dimensional (3D) NSMs. Subsequently, we focus an attention on recent progress in advanced NSMs as building blocks for EEDs (such as fuel cells, supercapacitors, and Li-ion batteries) based on investigations at the 0D, 1D, 2D and 3D NSMs.
Progress in Materials Science 05/2012; 57(4):724-803. · 18.22 Impact Factor
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ABSTRACT: High-quality, free-standing, and vertically interconnected three-dimensional (3-D) graphitic nanosheets (GNSs) were synthesized
over the surface of hemispherical carbon particles/GaN at 700°C by microwave plasma chemical vapor deposition (CVD) in presence
of methane gas, whereas the hemispherical carbon particles have been directly deposited on GaN/sapphire template. The GNSs
are ∼1–5nm in thickness and have a graphitic flake structure on hemispherical carbon particles. The vertically interconnected
3-D GNSs on hemispherical carbon particles have been characterized by scanning electron microscopy, transmission electron
microscopy, selective area electron diffraction pattern, X-ray diffraction, atomic force microscopy, Raman spectroscopy, X-ray
photoelectron spectroscopy, and nitrogen gas adsorption-Brunauer-Emmet-Teller. The present CVD approach is capable of producing
large quantities of GNSs with high purity. Moreover, a high-purity free-standing and vertically interconnected 3-D GNSs on
hemispherical carbon particles have an enormous potential for applications in electronic devices, biological sensors, gas
uptake and storage, fuel cells, lithium ion batteries, and more.
KeywordsMicrowave plasma CVD–Graphitic nanosheets–Electron microscopy–Surface properties
Plasmonics 04/2012; 6(1):67-73. · 2.99 Impact Factor
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ABSTRACT: Perfect platinum (Pt) nanocubes with high density have been synthesized by controlled reduction of hexachloroplatinic acid
in the presence of H2SO4 and HCl, employing a pair of low-resistivity fastened silicon (FS) wafers at room temperature. The presence of the additive
charges (induced by prior etching of the silicon surface with HF to remove any SiO2 layer) between the interfaces of the FS surface results in a high charge density and facilitates fast deposition of Pt nanoparticles
via electroless plating. The charge density, stirring time, and homogeneity of the aqueous solution influenced the geometrical
shapes of the Pt nanoparticles. The parameters were finely tuned in order to control the nucleation and growth rates and obtain
perfect Pt nanocubes. The perfect Pt nanocubes were single crystalline with exposed {100} facets. Per equivalent Pt surface
areas, the perfect Pt nanocubes showed enhanced catalytic activity relative to truncated Pt nanocubes or spherical Pt nanoparticles
for the electrooxidation of liquid feed fuels such as methanol and ethanol. Moreover, there a strong correlation was observed
between the optical, electrical, thermal, magnetic, and catalytic properties of the perfect Pt nanocubes which should lead
to a variety of technological applications of these materials.
KeywordsFastened silicon wafers–charge density–Pt nanocubes–catalytic activity–liquid feed fuel cells
Nano Research 04/2012; 4(6):541-549. · 6.97 Impact Factor
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ABSTRACT: Here we demonstrate a facile approach to grow uniform and large area single layer graphene directly over polycrystalline metal foil from fullerene, where fullerene molecules formed rod-like polycrystals in the toluene solvent. The generated pressure on sandwich structures has enhanced the density (scalable) as well as quality of graphene at partially low temperatures.
Chemical Communications 02/2012; 48(24):3003-5. · 6.17 Impact Factor
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ABSTRACT: Nucleation of diamond is of great importance for its growth, and a detailed understanding of the nucleation process is, therefore, desired for many applications. The pretreatment of the substrate surface may impact the initial growth period. This study demonstrates the synthesis of diamond films by microwave plasma chemical vapor deposition on a Pt/SiO2/Si substrate. The Pt particles were deposited on the SiO2/Si surface at room temperature, whereas adamantane was seeded on the SiO2/Si surface by ultrasonic treatment. The Pt particles on the SiO2 surface behave as a catalyst, which adsorb hydrocarbons from adamantane contained plasma and give distinct features of carbon in the early stage deposition. The adamantane transforms not only in the nanodiamond phase but also in other carbon phases, which can then act as nuclei for diamond growth. These kinds of phases enhanced the diamond density at partially low temperature deposition. The presence of an oxide intermediate layer between Pt and Si prevents silicidation as well as SiC in diamond deposition.
07/2011;
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ABSTRACT: A new organic-organic nanoscale composite thin-film (NCTF) dielectric has been synthesized by solution deposition of 1-bromoadamantane and triblock copolymer (Pluronic P123, BASF, EO20-PO70-EO20), in which the precursor solution has been achieved with organic additives. We have used a sol-gel process to make a metal-insulator-metal capacitor (MIM) comprising a nanoscale (10 nm-thick) thin-film on a flexible polyimide (PI) substrate at room temperature. Scanning electron microscope and atomic force microscope revealed that the deposited NCTFs were crack-free, uniform, highly resistant to moisture absorption, and well adhered on the Au-Cr/PI. The electrical properties of 1-bromoadamantane-P123 NCTF were characterized by dielectric constant, capacitance, and leakage current measurements. The 1-bromoadamantane-P123 NCTF on the PI substrate showed a low leakage current density of 5.5 x 10(-11) A cm(-2) and good capacitance of 2.4 fF at 1 MHz. In addition, the calculated dielectric constant of 1-bromoadamantane-P123 NCTF was 1.9, making them suitable candidates for use in future flexible electronic devices as a stable intermetal dielectric. The electrical insulating properties of 1-bromoadamantane-P123 NCTF have been improved due to the optimized dipole moments of the van der Waals interactions.
ChemSusChem 09/2010; 3(9):1051-6. · 6.83 Impact Factor
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ABSTRACT: Platinum (Pt) nanopetals were electrodeposited on highly ordered silicon nanocones (SiNCs) and explored as the electrocatalyst for methanol oxidation reaction (MOR) for direct methanol fuel cells applications. Highly ordered SiNCs array fabricated using the porous anodic aluminum oxide as the template had a high surface area. Well-dispersed Pt nanopetals possessing high electrocatalytic surface area was synthesized by pulse-electrodeposition on the SiNCs. Pt nanopetals loaded on highly ordered SiNC support exhibited very good catalytic activity for MOR and a high tolerance against CO poisoning, as compared to Pt nanoflowers/flat Si, Pt nanoparticles/flat Si, and many previously reported works. The abundance of a large surface area for facile transport of methanol, SiO(2) sites in the vicinity of the SiNCs, as well as less contact area between the Pt nanopetals catalyst and SiNCs are suggested to be the major factors enhancing the electrocatalytic performance of the Pt nanopetal/SiNC electrode. Moreover, we believe this new nanostructure (Pt nanopetals/SiNCs) will enable many new advances in nanotechnology.
ACS Applied Materials & Interfaces 08/2010; 2(8):2231-7. · 4.53 Impact Factor
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ABSTRACT: A 3D nanoporous graphitic carbon (g-C) material is synthesized by using an adamantane (C(10)H(16)) flame, and utilized to support a Pt(50)-Ru(50) alloy catalyst. The physico-chemical properties of the Pt(50)-Ru(50)/3D nanoporous g-C electrode are examined by a range of spectroscopy techniques as well as Brunauer-Emmett-Teller surface area analysis. Cyclic voltammetry measurements are used for electrochemical characterization of the Pt(50)-Ru(50)/3D nanoporous g-C electrode. The electrochemical investigations show that the supported Pt(50)-Ru(50) has excellent activity and stability towards methanol electro-oxidation. Good CO tolerance is also shown, and considered to be due to the presence of Ru nanoparticles. It is proposed that Ru is able to promote the oxidation of strongly adsorbed CO on Pt by supplying an oxygen source: Ru(OH)(ad). Moreover, the presence of 3D nanopores in the g-C support may also contribute to the observed higher current density by virtue of the easy transport of methanol and the oxidation products through these nanopores.
ChemSusChem 04/2010; 3(4):460-6. · 6.83 Impact Factor
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ABSTRACT: A two-dimensional continuous Pt island network was successfully synthesized by pulse-potentiostatic electrodeposition on a flat silicon substrate, which showed markedly enhanced catalytic activity toward methanol electrooxidation and high CO tolerance, probably due to the synergistic effect of the Pt island catalyst and surrounding SiO(2) surface layer.
Chemical Communications 01/2009; · 6.17 Impact Factor
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ABSTRACT: This study pulse-electrodeposits Pt nanoparticles on amorphous carbon-coated silicon nanocones (ACNCs) and explores them as the electrocatalyst for methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) for direct methanol fuel cell applications. The work prepares silicon nanocones on the Si wafer using porous anodic aluminum oxide as the template and then deposits the amorphous carbon layer on the nanocones by microwave plasma chemical vapor deposition. According to Raman scattering and X-ray photoelectron spectroscopies (XPS), the surface of the ACNC support is composed of a nanocrystalline graphitic structure, and rich in oxygen-containing adspecies. The Pt nanoparticles pulse-electrodeposited on the highly ordered ACNC support disperses well with a large electrocatalytic surface area. The Pt/ACNC electrode exhibits excellent electrocatalytic activity and stability toward both MOR and ORR. This study suggests the abundant oxygen-containing surface species and the nanometer size of the Pt catalyst as the two major factors enhancing electrocatalytic performance of Pt/ACNC electrode. The XPS study suggests the occurrence of charge transfer from π-sites of the graphitic structure to the Pt nanoparticle, thereby improving the electrochemical stability of the electrode.
Journal of Power Sources.
