The
electrical conductivity of carbon nanotubes (CNTs) has been
demonstrated to be highly sensitive to the change of vapor/gas molecules
in the local environment owing to the large specific surface area
and quantum size effect, which enable CNTs to be an ideal sensing
material for next-generation room-temperature gas sensors. However,
the sensing properties of CNT films or networks cannot be maximized
because of the inevitable agglomeration during the fabrication process.
Herein, three-dimensional (3D) SiO2@multiwalled CNTs (MWCNTs)
core–shell nanospheres have been first used to fabricate room-temperature
gas sensors, which were prepared using an electrostatic self-assembly
method. The as-fabricated 3D SiO2@MWCNTs sensor exhibits
a recorded sensitivity of 82.61% toward 1 ppm nitrogen dioxide (NO2) at room temperature, which is 1.97 times higher than that
of devices based on random two-dimensional (2D) MWCNTs. Meanwhile,
the recovery time of ∼44 s is smaller than that of a 2D MWCNT
gas sensor. Such an ultrahigh sensing performance is attributed to
an effective utilization of the large specific surface area of MWCNT
networks with 3D structures. We believe that our findings will contribute
to the further development of high-performance CNT-based sensing devices
and also provide a new approach to fabricate the sensing devices using
one-dimensional nanomaterials.
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