Enhanced Stability Effect in Composite Polymeric Nanofibers Containing Titanium Dioxide and Carbon Nanotubes

Abstract

Composite poly(acrylonitrile) nanofibers containing nanometric TiO 2 particles and multiwalled carbon nanotubes have been prepared by the electrospinning technique. The photocatalytic activity of the composite fibers was measured in the absence of contaminants as well as with acetone, or with the dye rhodamine 6G. TEM images, as well as FTIR measurements, showed that the presence of carbon nanotubes reduced the extent by which the polymeric matrix was degraded upon exposure to UV light. At the same time, no adverse effect on the ability of the photocatalyst to degrade organic molecules was observed, and in the case of rhodamine 6G, an enhanced degradation rate was observed. These apparently contradicting results are explained by a mechanism that is based on the transport of photoinduced charge carriers from the photocatalyst particles to the carbon nanotubes, which may induce a variety of effects, depending on the degradation mechanism and reaction loci.

Effect of Bed Height on the Performance of a Fixed Mo/HZSM‐5 Bed in Direct Aromatization of Methane

“…The second mechanism for reducing recombination in particulate systems is through the spatial separation of charges induced by the presence of surface domains that are made of materials (usually metals or oxides), the Fermi level of which is appropriate for the selective acceptance of one of the charge carriers. In photocatalytic degradation of contaminants, these domains, usually made of Pt,25 Au,26 Ag,27 WO 3 ,28 and carbon nanotubes (CNTs),29 are electron sinks. Such domains are also used in WS, mostly as electron sinks, (e.g.…”

“…Here, because the redox potential of almost all organic compounds is significantly more negative than that of OH radicals, once OH radicals are formed and reach the molecule to be oxidized, no differentiation according to the exact type of the chemical species should be expected 51. Therefore, rate enhancement can be obtained by facilitating adsorption in close proximity to the photocatalytic sites, as demonstrated when using inert substrates, such as zeolites,52 silica,53 activated carbon,54, 55 and even CNTs 29. Moreover, by controlling adsorption, it is possible to achieve specificity, either by selective physisorption at the vicinity of the sites (“adsorb and shuttle”)56–58 or by molecular imprinting on the surface of the photocatalyst 59…”

Nanoscale structures in photocatalysis: Dense films, molecular imprinting and composites

“…A second example for the role of nano-scale structures in photocatalysis is the use of composite nanofibers, made by electrospinning and comprising of a poly(acrylonitrile) (PAN) matrix into which both TiO 2 particles and carbon nanotubes are embedded [ 8 ]. I-V measurements were performed on the various fibers (PAN-TiO 2 , PAN-MWCNT-TiO 2 ) by positioning a SPM conductive tip at specific loci on the fibers and measuring the current as a function of applied bias.…”

Extending the photoelectrocatalytic detection range of KHP by eliminating self-inhibition at TiO2 nanoparticle electrodes

“…Titanium dioxide (TiO 2 ) nanomaterials are considered to be excellent and promising heterogeneous photocatalysts for environmental improvement and analysis due to their environmentally friendly properties and superior oxidation power [1][2][3][4]. Their oxidation capacities arise mainly from photoholes (h + ) and/or active oxygen species (AOS), including radicals that can readily decompose a wide spectrum of organic compounds [5][6][7][8].…”