Heterojunctions of Ta2O5 and multiwalled
carbon nanotubes (MWCNTs) have been successfully synthesized by a
facile and cost-effective hydrothermal method, with a super thin and
uniform Ta2O5 shell wrapped around the MWCNT.
The combination of Ta2O5 and MWCNTs at the interface
not only modifies the morphology but also forms the p–n heterojunction,
which contributes to the reconstruction of band structure, as well
as the low resistance of matrix and highly chemisorbed oxygen content.
The Ta2O5@MWCNT p–n heterojunction exhibits
ultrasensitive performance to ethanol at room temperature, with a
response of 3.15 toward 0.8 ppm ethanol and a detection limit of 0.173
ppm. The sensor has a high reproducibility at various concentrations
of ethanol, superior selectivity to other gases, and long-term stability.
The strategy of hybriding metal oxide semiconductors with MWCNT promises
to provide a feasible and further developable pathway for high-performance
room-temperature gas sensors.