Sustainable energy is currently limited by the ability of materials to store energy and deliver it on demand. Allotropes of carbon are attractive for their potential for use in energy storage due to low weight, high c...
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Using density-functional theory within the generalized gradient approximation, we investigate the energetics of oxygen subsurface adsorption governing the onset of bulk oxidation of Cu(100) surface. It shows that the ...
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Using density-functional theory within the generalized gradient approximation, we investigate the energetics of oxygen subsurface adsorption governing the onset of bulk oxidation of Cu(100) surface. It shows that the presence of boundaries formed from merged missing-row nanodomains mismatched by a half unit-cell leads to preferred oxygen adsorption at the subsurface tetrahedral sites. The resulting Cu-O tetrahedrons along the domain boundary strikingly resemble that of the bulk oxide phase of Cu2O. These results provide direct atomic-scale insight into the microscopic origin of the crystallographic orientation relationships for oxide overlayer growth. Our results also suggest that the oxidation of an atomically flat terrace can still be a heterogeneous nucleation process controlled by defects in the oxygen-chemisorbed adlayer.
Fluorescence Quenching Microscopy has been shown to be an effective means of characterizing graphene on the macroscale. Centimeter-scale CVD-grown pristine and doped graphene were manufactured in a high temperature (1...
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Fluorescence Quenching Microscopy has been shown to be an effective means of characterizing graphene on the macroscale. Centimeter-scale CVD-grown pristine and doped graphene were manufactured in a high temperature (1000°C) furnace on pristine copper substrates. The copper was then etched away in a FeCl3solution and the graphene was coated with DCM-based fluorescent dye before being imaged in a fluorescence microscope. The fluorescence image was then image-processed using modified Matlab software. The resulting image showed clear contrast between the pristine graphene sheet and defects on the graphene surface, which revealed that fluorescence microscopy could determine the quality of a large region of graphene. Also, significant contrast was identified between single-layer and multi-layer regions, showing that this technique is also effective at determining the degree of uniformity within a graphene sample. Lastly, the fluorescence images showed contrast between doped and undoped regions of graphene.
Fabrication of graphene was demonstrated by electrochemical exfoliation of graphite in an ammonium hydroxide solution. The processing parameter of applied voltage was optimized to accomplish graphene productivity and ...
Fabrication of graphene was demonstrated by electrochemical exfoliation of graphite in an ammonium hydroxide solution. The processing parameter of applied voltage was optimized to accomplish graphene productivity and desired chemical composition. Images from the atomic force microscopy showed graphene sheets with lateral sizes of several hundred nanometers. Images from the transmission electron microscopy indicated the existence of stacked graphene sheets with thickness of a few graphene layers. Raman spectroscopy confirmed variation of as-synthesized graphene and bulk graphite. X-ray photoemission spectroscopy suggested the formation of graphene oxide at large voltage.
Silicon nanodevice biosensors have been attracted a lot of attention due to its advantages of label-free, real-time and very high sensitive detection. This study employs self-assembly monolayer (SAM) of methoxy-poly(e...
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ISBN:
(纸本)9781457717666
Silicon nanodevice biosensors have been attracted a lot of attention due to its advantages of label-free, real-time and very high sensitive detection. This study employs self-assembly monolayer (SAM) of methoxy-poly(ethyleneglycol) silane (MPEG-sil) as passivation on Si nanodevices. Ablation of SAM by Joule heating (JH) was performed at n - region of a nanobelt device, where the linker molecules, biotin were modified subsequently. Detection of Alexa dye-labeled Streptavidin (SA) showed that the fluorescence intensity at n - region increased with each 50-μl SA injection and saturated after the 4 th injection. A difference of fluorescence intensity between SAM-ablated device and without passivation is 4.9 fold. Threshold voltage (V th ) shifted ca. 35 mV after the 4 th injection for SAM-ablated device and as-fabricated device exhibited only a 10-mV V th shift. The results indicated that SAM-ablated device possess potential in reduction of sensing time and in increase of sensitivity for low concentration detection.
We review our recent work that employs a series of computational techniques including density functional theory, ab initio molecular dynamics, and classical molecular dynamics to investigate changes in the structure a...
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We have investigated the effect of varying the film thickness on the surface orientation texturing in polycrystalline Si films obtained via mixed-phase solidification (MPS) of initially a-Si precursor films on SiO2. I...
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We have investigated the effect of varying the film thickness on the surface orientation texturing in polycrystalline Si films obtained via mixed-phase solidification (MPS) of initially a-Si precursor films on SiO2. It is found that, for a given number of MPS exposure cycles, the degree of (100)-surface texturing is reduced as the film thickness is increased. We discuss how this trend can be accounted for by the previously proposed thermodynamic model of MPS, wherein a decreasing local solid/liquid interface curvature with increasing film thickness is identified as the primary cause for decreasing the influence which anisotropic solid-Si/SiO2 interfacial energies have on the survivability of the grains. This, in turn, leads to other factors becoming more significant in determining the grains that survive the MPS cycle, thereby reducing the degree of (100)-surface texturing in the resulting films.
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