MXenes,
two-dimensional transition metal carbides or nitrides,
have recently shown great promise for gas sensing applications. We
demonstrate that the sensitivity of intrinsically metallic Ti3C2T
x
MXene can be considerably
improved via its partial oxidation in air at 350 °C. The annealed
films of MXene sheets remain electrically conductive, while their
decoration with semiconducting TiO2 considerably improves
their chemiresistive response to organic analytes at low-ppm concentrations
in dry air, which was used to emulate practical sensing environments.
We demonstrate that partially oxidized MXene has a faster and a qualitatively
different sensor response to volatile analytes compared to pristine
Ti3C2T
x
. We fabricated
multisensor arrays of partially oxidized Ti3C2T
x
MXene devices and demonstrate that
in addition to their high sensitivity they enable a selective recognition
of analytes of nearly the same chemical nature, such as low molecular
weight alcohols. We investigated the oxidation behavior of Ti3C2T
x
in air in a wide
temperature range and discuss the mechanism of sensor response of
partially oxidized MXene films, which is qualitatively different from
that of pristine Ti3C2T
x
.
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