The design of multifunctional
nanostructured materials is the key
to the development of smart wearable devices. For instance, nanostructures
endowed with both piezoelectric and photocatalytic activities could
well be the workhorse for solar-light-driven self-cleaning wearable
sensors. In this work, a simple strategy for the assembly of a flexible,
semitransparent piezophotocatalytic system is demonstrated by leveraging
rational wet chemistry synthesis of ZnO-based nanosheets/nanoflowers
(NSs/NFs) under basic pH conditions onto flexible ITO/PET supports.
A KMnO4pretreatment before the ZnO synthesis (seeded ZnO)
allows for the control of the density, size, and orientation of the
NSs/NFs systems compared to the systems produced in the absence of
seeding (seedless ZnO). The electrical response of the sensors is
extracted at a 1 V bias as a function of bending in the interval between
0 and 90°, being the responsivity toward bending significantly
enhanced by the KMnO4treatment effect. The photocatalytic
activity of the sensors is analyzed in aqueous solution (methylene
blue, 25 μM) by a solar simulator, resulting in similar values
between seedless and seeded ZnO. Upon bending the sensor, the photocatalytic
activity of seedless ZnO is almost unaffected, whereas that of seeded
ZnO is improved by about 25%. The sensor’s reusability and
repeatability are tested in up to three different cycles. These results
open up the way toward the seamless integration of bending sensitivity
and photocatalysis into a single device.