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Correlation of Optical Properties, Electronic Structure, and Photocatalytic Activity in Nanostructured Tungsten Oxide
Author(s) -
Ling Min,
Blackman Christopher S.,
Palgrave Robert G.,
SoteloVazquez Carlos,
Kafizas Andreas,
Parkin Ivan P.
Publication year - 2017
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201700064
Subject(s) - materials science , nanorod , tungsten trioxide , photocatalysis , band gap , tungsten , oxide , chemical bath deposition , chemical engineering , nanotechnology , inorganic chemistry , optoelectronics , metallurgy , catalysis , chemistry , organic chemistry , engineering
Tungsten trioxide nanorod arrays are deposited using aerosol assisted chemical vapor deposition. The electronic structure, defect chemistry, optical bandgap, and photocatalytic activity are found to vary progressively with nanorod length. Nanorods less than 1 µm in length show a widening of the optical bandgap (up to 3.1 eV), more disorder states within the bandgap, an absence of reduced tungsten cation states, and increased photocatalytic activity for destruction of a test organic pollutant (stearic acid) compared to nanorods of 2 µm length or greater which possessed bandgaps close to the bulk value for tungsten oxide (2.6–2.8 eV), the presence of reduced tungsten states (W 4+ ), and lower photocatalytic activity. The results indicate that for maximum photocatalytic performance in organic pollutant degradation, tungsten oxide should be engineered such that the bandgap is widened relative to bulk WO 3 to a value above 3 eV; although less photons are expected be absorbed, increases in the overpotential for oxidation reactions appear to more than offset this loss. It is also desirable to ensure the material remains defect free, or the defect concentration minimized, to minimize carrier recombination.