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Composite number
About: Composite number is a research topic. Over the lifetime, 103455 publications have been published within this topic receiving 1206169 citations.
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01 Apr 2012
TL;DR: The enhancement in photocatalytic performance of the MWCNT/TiO(2) composite is explained in terms of recombination of photogenerated electron-hole pairs, which adds to the global discussion of how CNTs can enhance the efficiency of catalysts.
Abstract: The high rate of electron/hole pair recombination reduces the quantum yield of the processes with TiO2 and represents its major drawback. Adding a co-adsorbent increases the photocatalytic efficiency of TiO2. In order to hybridize the photocatalytic activity of TiO2 with the adsorptivity of carbon nanotube, a composite of multi-walled carbon nanotubes and titanium dioxide (MWCNT/TiO2) has been synthesized. The composite was characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared absorption spectroscopy (FTIR), and diffuse reflectance UV–vis spectroscopy. The catalytic activity of this composite material was investigated by application of the composite for the degradation of methyl orange. It was observed that the composite exhibits enhanced photocatalytic activity compared with TiO2. The enhancement in photocatalytic performance of the MWCNT/TiO2 composite is explained in terms of recombination of photogenerated electron–hole pairs. In addition, MWCNT acts as a dispersing agent preventing TiO2 from agglomerating activity during the catalytic process, providing a high catalytically active surface area. This work adds to the global discussion of how CNTs can enhance the efficiency of catalysts.
906 citations
TL;DR: In this paper, a tetraoctylammonium bromide (TOAB)-capped metal nanoparticles on TiO2 films improved the photocurrent generation and induced a shift in the apparent flat band potential.
Abstract: Noble metal particles of Au, Pt, and Ir were deposited on nanostructured TiO2 film using an electrophoretic approach. The nanocomposite films were characterized by UV-absorption and atomic force microscopy (AFM). The deposition of tetraoctylammonium bromide (TOAB)-capped metal nanoparticles on TiO2 films improved the photocurrent generation and induced a shift in the apparent flat band potential. The TiO2 films modified with TOAB-capped metal nanoparticles were less prone to the electron scavenging by the oxygen in solution. Improved photoelectrochemical performance of semiconductor−metal composite film is attributed to the shift in quasi-Fermi level of the composite to more negative potentials. Continuous irradiation of the composite films over a long period causes photocurrent to decrease as the semiconductor−metal interface undergoes chemical changes. The role of semiconductor−metal composite films in improving the rate of photocatalytic degradation of an azo dye is also discussed.
897 citations
TL;DR: In this article, the authors report the observation of single nanotube fragmentation, under tensile stresses, using nanotubes-containing thin polymeric films, and they estimate that the multi-wall multi-nanotube-matrix stress transfer efficiency is at least one order of magnitude larger than in conventional fiber-based composites.
Abstract: We report the observation of single nanotube fragmentation, under tensile stresses, using nanotube-containing thin polymeric films. Similar fragmentation tests with single fibers instead of nanotubes are routinely performed to study the fiber-matrix stress transfer ability in fiber composite materials, and thus the efficiency and quality of composite interfaces. The multiwall nanotube-matrix stress transfer efficiency is estimated to be at least one order of magnitude larger than in conventional fiber-based composites.
897 citations
TL;DR: The cumulative high-capacity value is attributed to the unique property of the nano V(2)O(5)/CNTs composite, which provides a short diffusion path for Li(+)-ions and an easy access to vanadium redox centers besides the high conductivity of CNTs.
Abstract: Functionalized multiwalled carbon nanotubes (CNTs) are coated with a 4–5 nm thin layer of V2O5 by controlled hydrolysis of vanadium alkoxide. The resulting V2O5/CNT composite has been investigated for electrochemical activity with lithium ion, and the capacity value shows both faradaic and capacitive (nonfaradaic) contributions. At high rate (1 C), the capacitive behavior dominates the intercalation as 2/3 of the overall capacity value out of 2700 C/g is capacitive, while the remaining is due to Li-ion intercalation. These numbers are in agreement with the Trasatti plots and are corroborated by X-ray photoelectron spectroscopy (XPS) studies on the V2O5/CNTs electrode, which show 85% of vanadium in the +4 oxidation state after the discharge at 1 C rate. The cumulative high-capacity value is attributed to the unique property of the nano V2O5/CNTs composite, which provides a short diffusion path for Li+-ions and an easy access to vanadium redox centers besides the high conductivity of CNTs. The composite arc...
867 citations
TL;DR: Transparent and electrically conductive composite silica films were fabricated on glass and hydrophilic SiOx/silicon substrates by incorporation of individual graphene oxide sheets into silica sols followed by spin-coating, chemical reduction, and thermal curing.
Abstract: Transparent and electrically conductive composite silica films were fabricated on glass and hydrophilic SiOx/silicon substrates by incorporation of individual graphene oxide sheets into silica sols followed by spin-coating, chemical reduction, and thermal curing. The resulting films were characterized by SEM, AFM, TEM, low-angle X-ray reflectivity, XPS, UV−vis spectroscopy, and electrical conductivity measurements. The electrical conductivity of the films compared favorably to those of composite thin films of carbon nanotubes in silica.
863 citations