2 research outputs found
Micropatternable Double-Faced ZnO Nanoflowers for Flexible Gas Sensor
Micropatternable
double-faced (DF) zinc oxide (ZnO) nanoflowers (NFs) for flexible
gas sensors have been successfully fabricated on a polyimide (PI)
substrate with single-walled carbon nanotubes (SWCNTs) as electrode.
The fabricated sensor comprises ZnO nanoshells laid out on a PI substrate
at regular intervals, on which ZnO nanorods (NRs) were grown in- and
outside the shells to maximize the surface area and form a connected
network. This three-dimensional network structure possesses multiple
gas diffusion channels and the micropatterned island structure allows
the stability of the flexible devices to be enhanced by dispersing
the strain into the empty spaces of the substrate. Moreover, the micropatterning
technique on a flexible substrate enables highly integrated nanodevices
to be fabricated. The SWCNTs were chosen as the electrode for their
flexibility and the Schottky barrier they form with ZnO, improving
the sensing performance. The devices exhibited high selectivity toward
NO<sub>2</sub> as well as outstanding sensing characteristics with
a stable response of 218.1, fast rising and decay times of 25.0 and
14.1 s, respectively, and percent recovery greater than 98% upon NO<sub>2</sub> exposure. The superior sensing properties arose from a combination
of high surface area, numerous active junction points, donor point
defects in the ZnO NRs, and the use of the SWCNT electrode. Furthermore,
the DF-ZnO NF gas sensor showed sustainable mechanical stability.
Despite the physical degradation observed, the devices still demonstrated
outstanding sensing characteristics after 10 000 bending cycles
at a curvature radius of 5 mm
Recovery Improvement for Large-Area Tungsten Diselenide Gas Sensors
Semiconducting
two-dimensional transition-metal dichalcogenides are considered promising
gas-sensing materials because of their large surface-to-volume ratio,
excellent electrical conductivity, and susceptible surfaces. However,
enhancement of the recovery performance has not yet been intensively
explored. In this study, a large-area uniform WSe<sub>2</sub> is synthesized
for use in a high-performance semiconductor gas sensor. At room temperature,
the WSe<sub>2</sub> gas sensor shows a significantly high response
(4140%) to NO<sub>2</sub> compared to the use of NH<sub>3</sub>, CO<sub>2</sub>, and acetone. This paper demonstrates improved recovery of
the WSe<sub>2</sub> gas sensor’s NO<sub>2</sub>-sensing performance
by utilizing external thermal energy. In addition, a novel strategy
for improving the recovery of the WSe<sub>2</sub> gas sensor is realized
by reacting NH<sub>3</sub> and adsorbed NO<sub>2</sub> on the surface
of WSe<sub>2</sub>: the NO<sub>2</sub> molecules are spontaneously
desorbed, and the recovery time is dramatically decreased (85 min
→ 43 s). It is expected that the fast recovery of the WSe<sub>2</sub> gas sensor achieved here will be used to develop an environmental
monitoring system platform