Mesoporous Titanium Dioxide Nanofibers with a Significantly Enhanced Photocatalytic Activity

Abstract

Mesoporous TiO2 nanofibers with controlled diameter, crystal size, and anatase versus rutile crystal structures are produced by calcination at 500–700 °C of precursor nanofibers of polyvinylpyrrolidone and titanium isopropoxide, obtained from a scalable gas jet fiber spinning process. These TiO2 nanofibers are used in the photocatalytic oxidation of gas‐phase ethanol at room temperature on exposure to UV irradiation. The experimental trends are analyzed using electron–hole (e‐h) charge recombination inferred from high‐intensity photoluminescence emission spectra, specific surface area, crystallinity, and the proportions of anatase and rutile phases. The nanofibers show a photocatalytic activity that is up to an order of magnitude higher than that of commercial‐grade P25 TiO2 nanoparticles because of slower e‐h recombination phenomena in the former. The results show that ethanol undergoes complete oxidation into CO2 and H2O on the nanofibers without the accumulation of the intermediate products acetaldehyde and formic acid.

Fabrication of Hierarchical V2O5 Nanorods on TiO2 Nanofibers and Their Enhanced Photocatalytic Activity under Visible Light

“…[24,26,37] We recentlyd emonstrated high-rate fabrication of mesoporous TiO 2 nanofibers with controlled crystal structuresu sing the needle-tip gas jet fiber (GJF) spinning method [38,39,40] and subsequent high-temperature calcination of precursor fibers. [9,41] The mesoporousT iO 2 nanofibers showeds ignificantly higher photocatalytic activity at room temperatureu nder UV spectrum of the incident light than commercial-grade P25-TiO 2 nanoparticles. In view of this, one can anticipate that the bicomponent V 2 O 5 -TiO 2 heterostructure can be an interesting system for exploring the photocatalytic properties under visible-lighti rradiation.…”

“…by alteringt heir morphology,s urfaces tructure-properties, and the composition. [9,14,16,20] One dimensional( 1D)f ibrousm orphology of SMO nanostructures can have higher photocatalytic efficiency [9,21,22] thanks to their large surface-to-volume ratio, enhanced light scattering and absorption, high transport rate of free electrons along the longitudinal direction, and efficient electron-hole charge utilization with high quantum efficiency.T he bicomponent heterostructures of controlled compositions and heterogeneous materials interfaces are particularly interesting. [23,24,[25][26][27] For example, Lao et al showedanew form of nanorods on nanowire morphologyo fZ nO-In 2 O 3 with heteroepitaxial growth of ZnO nanorods on an In 2 O 3 nanowire core synthesized from vapor transport andc ondensation technique, which are expensive and complex.…”

“…Photocatalytic oxidation can be considered an efficient and cost-effective methodf or this purpose, as someo ft hese processes work even at room temperature. [1,8,9] Several semiconducting metal oxides (SMO) are attractive materials for photocatalysis, such as titanium dioxide (TiO 2 ), vanadium pentoxide (V 2 O 5 ), zinc oxide (ZnO), tungsten oxide (WO 3 ), and tin dioxide (SnO 2 ) [9,10] and offer highp hotocatalytic activitiesa tr oom temperatures. [11] TiO 2 is ap romising photoca-talyst for hydrogen production and find applications as selfcleanings urfaces, as antibacterial materials, or in solar andf uel cells.…”

“…[12,13] TiO 2 particles are naturally abundant and offer strong oxidizingp owerf or decomposition of toxic organic compounds. [9,13] However,t he wide band-gap energy (E g )o fT iO 2 ( % 3.0-3.2 eV) limits itsp hotocatalytic activities to only the UV range of light.Am ajority of high-performance photocatalyst systemsw ork only under UV light, [9] although the natural solar light only contains % 5-7 %U V-light irradiation of the entire solar spectrum,t husl imiting the extent of photocatalytic reactivity in many practical applications. [11] Visible-light-induced photoreactivity of TiO 2 was improved by doping TiO 2 with other metalso rn onmetals, e.g.,m etal particleso fV ,P t, Pd, or Au, or nonmetalc arbon particles, and mixingw ith otherm etal oxides, such as SnO 2 ,Z nO, and V 2 O 5 .…”

“…The quantum yield is af unction of migration of the electrons and holes to the surface serving as the redox sources and is governed by the surface charge-carriert ransfer rate and the recombination rate of the photogenerated electron-hole pairs. [9] An umber of investigations addressed the enhancement of the photocatalytic efficiency of TiO 2…”