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Shape-enhanced photocatalytic activity of single-crystalline anatase TiO2 (101) nanobelts.

Authors
Wu-NQ; Wang-J; Tafen-D; Wang-H; Zheng-JG; Lewis-JP; Liu-XG; Leonard-SS; Manivannan-A
Source
J Am Chem Soc 2010 May; 132(19):6679-6685
NIOSHTIC No.
20037036
Abstract
Particle size is generally considered to be the primary factor in the design of nanocrystal photocatalysts, because the reduction of particle size increases the number of active sites. However, the benefit from the size reduction can be canceled by a higher electron-hole recombination rate due to the confined space in sphere-shaped nanoparticles. Here we report a mechanistic study on a novel nanobelt structure that overcomes the drawback of sphere-shaped nanoparticles. Single-crystalline anatase TiO2 nanobelts with two dominant surfaces of (101) facet exhibit enhanced photocatalytic activity over the nanosphere counterparts with an identical crystal phase and similar specific surface area. The ab initio density functional theory (DFT) calculations show that the exposed (101) facet of the nanobelts yields an enhanced reactivity with molecular O-2, facilitating the generation of superoxide radical. Moreover, the nanobelts exhibit a lower electron hole recombination rate than the nanospheres due to the following three reasons: (i) greater charge mobility in the nanobelts, which is enabled along the longitudinal dimension of the crystals; (ii) fewer localized states near the band edges and in the bandgap due to fewer unpassivated surface states in the nanobelts; and (iii) enhanced charge separation due to trapping of photogenerated electrons by chemisorbed molecular O-2 on the (101) facet. Our results suggest that the photocatalysis efficiency of nanocrystals can be significantly improved by tailoring the shape and the surface structure of nanocrystals, which provides a new concept for rational design and development of high-performance photocatalysts.
Keywords
Analytical-chemistry; Biological-effects; Chromatographic-analysis; Microscopy; Nanoparticles; Nanotechnology; Nanotubes; Particulate-dust; Particulates; Spectrographic-analysis
Contact
Nianqiang Wu, W Virginia Univ, Department of Mechanical and Aerospace Engineering, WV Nano Initiative, Morgantown, WV 26506
CODEN
JACSAT
Publication Date
20100519
Document Type
Journal Article
Email Address
nick.wu@mail.wvu.edu
Fiscal Year
2010
NTIS Accession No.
NTIS Price
Issue of Publication
19
ISSN
0002-7863
NIOSH Division
HELD
Priority Area
Manufacturing
Source Name
Journal of the American Chemical Society
State
WV
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