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Flutelike Porous Hematite Nanorods and Branched Nanostructures: Synthesis, Characterisation and Application for Gas‐Sensing
Author(s) -
Gou Xinglong,
Wang Guoxiu,
Kong Xiangyang,
Wexler David,
Horvat Joseph,
Yang Juan,
Park Jinsoo
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200701705
Subject(s) - nanorod , nanostructure , materials science , crystallite , chemical engineering , high resolution transmission electron microscopy , transmission electron microscopy , nanotechnology , hematite , porosity , composite material , metallurgy , engineering
Flute‐like porous α‐Fe 2 O 3 nanorods and branched nanostructures such as pentapods and hexapods were prepared through dehydration and recrystallisation of hydrothermally synthesised β‐FeOOH precursor. Transmission electron microscopy (TEM), high‐resolution TEM and selected area electron diffraction analyses reveal that the nanorods, which grow along the [110] direction, have nearly hollow cavities and porous walls with a pore size of 20–50 nm. The hexapods have six symmetric arms with a diameter of 60–80 nm and length of 400–900 nm. The growth direction of the arms in the hexapod‐like nanostructure is also along the [110] direction, and there is a dihedral angle of 69.5 o between adjacent arms. These unique iron oxide nanostructures offer the first opportunity to investigate their magnetic and gas sensing properties. The nanostructures exhibited unusual magnetic behaviour, with two different Morin temperatures under field‐cooled and zero‐field‐cooled conditions, owing to their shape anisotropy and magnetocrystalline anisotropy. Furthermore, the α‐Fe 2 O 3 nanostructures show much better sensing performance towards ethanol than that of the previously reported polycrystalline nanotubes. In addition, the α‐Fe 2 O 3 nanostructure based sensor can selectively detect formaldehyde and acetic acid among other toxic, corrosive and irritant vapours at a low working temperature with rapid response, high sensitivity and good stability.