In this report, the growth of zinc oxide (ZnO) nanocrystals with various morphologies, nanoflower, nanosheet, and nanorod, on flexible stainless steel (SS) foils to be utilized as photoanodes in photoelectrochemical (PEC) solar cells has been presented. It has been aimed to provide flexibility and adaptability for the next generation systems with the incorporation of SS foils as electrode into PEC cells. Therefore, physical deformation tests have been applied to the prepared ZnO thin film photoanodes. These thin films have been thoroughly characterized before and after straining for better understanding the relationship between the morphology, straining effect and photoelectrochemical efficiency. We observed a notable increase in the maximum incident photon-to-current efficiency (IPCE) and durability of all ZnO photoelectrodes after straining process. The increase in IPCE values by 1.5 and 2.5 folds at 370 nm has been observed for nanoflower and nanorod morphologies, respectively after being strained. The maximum IPCE of 69% has been calculated for the ZnO nanorod structures after straining. Bending of the SS electrodes resulted in the more oriented nanorod arrays compared to its flat counterpart, which improved both the light absorption and also the photo-conversion efficiency drastically. The finite-difference time-domain simulations have also been carried out to examine the optical properties of flat and bent ZnO electrodes. Finally, it has been concluded that SS photoanodes bearing ZnO semiconducting material with nanoflower and nanorod morphologies are very promising candidates for the solar hydrogen generator systems in terms of efficiency, durability, flexibility, and lightness in weight.
Introducing a zinc stannate, ZnSnO3 (ZTO), layer on
hydrothermally grown 3D-zinc oxide (ZnO) nanosheet thin films has
been proven to have a quenching effect on the photoluminescence emissions,
indicating very slow recombination of photoinduced electron–hole
pairs in photoelectrochemical water splitting (PEC) reactions. Motivated
by this, the ZnO/ZTO bilayer system has been used as the electron
transport layer for copper indium gallium sulfide (CIGS)-based photoelectrodes
in PEC applications. Furthermore, the poor photoresistivity of CIGS
has been improved via indium sulfide (In2S3)
deposition. Consequently, the photoelectrode obtained from the inverted
configuration, ZnO/ZTO/CIGS/In2S3, has generated
a photocurrent density of 6.4 mA cm–2 at 0.4 V (vs
Ag/AgCl), exceeding the performance of ZnO NS/CIGS/In2S3 photoelectrodes by three folds. The highest ABPE and IPCE
efficiencies have been calculated as 4.2% and 57%, respectively. More
importantly, two cost-effective nonvacuum techniques for large-scale
thin film fabrications such as chemical bath deposition (CBD) and
ultrasonic spray pyrolysis (USP) methods have been adopted to acquire
photoelectrodes with inverted configurations providing an advantageous
approach for low-cost photoelectrode design for sustainable energy
production.
In this study, zinc oxide (ZnO) powders in two different morphologies, nanowire (NW) and nanoflower (NF), have been synthesized by the hydrothermal method. The eligibility of the pristine ZnO nanopowders as a photo-active material has been revealed by designing P-SC devices via the facile drop-casting method on both glass and plastic substrates in large-area applications. The impact of physical properties and especially defect structures on photo-supercapacitor (P-SC) performance have been explored. Although the dark Coulombic efficiency (CE%) of both NW and NF-based P-SC were very close to each other, the CE% of NW P-SC increased 3 times, while the CE% of NF P-SC increased 1.7 times under the UV-light. This is because the charge carriers produced under light excitation, extend the discharge time, and as confirmed by electron paramagnetic resonance, photoluminescence, and transmission electron microscopy analyses, the performance of P-SCs made from NF powders was relatively low compared to those produced from NW due to the high core defects in NF powders. The energy density of 78.1 mWh kg−1 obtained for NF-based P-SCs is very promising, and the capacitance retention value of almost 100% for 3000 cycles showed that the P-SCs produced from these materials were entirely stable. Compared to the literature, the P-SCs we propose in this study are essential for new generation energy storage systems, thanks to their ease of design, adaptability to mass production for large-area applications, and their ability to store more energy under illumination.
In this study, three
different morphologies, nanoflower (NF), nano
sponge (NS), and nano urchin (NU), of zinc oxide (ZnO) nanostructures
were synthesized successfully via a mild hydrothermal method. After
synthesis, the samples were annealed in the atmosphere at 300, 600,
and 800 °C. Although annealing provides different degradation
kinetics for different morphologies, ZnO NS performed significantly
better than other morphologies for all annealing temperatures we used
in the study. When the photoluminescence, electron paramagnetic resonance
spectroscopy, BET surface, and X-ray diffraction analysis results
are examined, it is revealed that the defect structure, pore diameter,
and crystallinity cumulatively affect the photocatalytic activity
of ZnO nanocatalysts. As a result, to obtain high photocatalytic activity
in rhodamine B (RhB) degradation, it is necessary to develop a ZnO
catalyst with fewer core defects, more oxygen vacancies, near band
emission, large crystallite size, and large pore diameter. The ZnO
NS-800 °C nanocatalyst studied here had a 35.6 × 10–3 min–1 rate constant and excellent
stability after a 5-cycle photocatalytic degradation of RhB.
This work reports
a one-pot chemical bath deposition (CBD) method
for the preparation of selectively grown, morphology-tunable zinc
oxide (ZnO) nanostructures provided via straightforward nanosecond
fiber laser ablation. Nanosecond fiber laser ablation is different
from lithographic methods due to its simple, time saving, and efficient
film scribing abilities. Here, multiple morphologies of the ZnO nanostructures
on the same substrate have been grown via laser ablation of the ZnO
seeding layer. Selective and controlled ablation of the titanium layer,
ZnO growth inhibitor, resulted in systematic growth of nanorod arrays,
while the application of extensive fluence energies resulted in the
penetration of the laser beam until the glass substrate induced the
nanoflake growth within the same CBD environment. The laser penetration
depth has been numerically investigated via COMSOL Multiphysics heat
module simulations, and the optical variations between two nanostructures
(nanorod and nanoflake) have been examined via Lumerical FDTD. The
simultaneous growth of two morphologies served as an efficient tool
for the enhancement of photoluminescence intensities. It increased
the average charge carrier lifetimes of the thin films from approximately
2.01 to 9.07 ns under the same excitation wavelengths. The amplification
in PL performances has been accomplished via the capstone of all-inorganic
halide perovskite (IHP) deposition that brought a successful conclusion
to lifetime responses, which have been increased by 1.4-fold. The
development of IHP sensitized nanoscaled multimorphological ZnO thin
films can, therefore, be used as potential nanomaterials for light-emitting-device
applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.