Green hydrogen production is one of the most desirable
sustainable
goals of the United Nations. Thus, for that purpose, we developed
hematite (α-Fe
2
O
3
), an n-type semiconductor,
a desirable candidate for photoelectrochemical (PEC) water splitting,
enabling hydrogen evolution. High recombination losses, low efficiency,
and large-scale production hinder its potential. To address these
issues, we have fabricated optimized bare and cadmium oxide (CdO)-decorated
hematite thin film nanorod arrays using a throughput radio frequency
(RF) sputtering with efficient water splitting behavior. To the best
of our knowledge, no work has been done so far on the synthesis of
CdO/α-Fe
2
O
3
via RF sputtering for PEC
application. Bare α-Fe
2
O
3
samples, with
a morphology of vertically aligned nanorods, were fabricated with
optimized parameters such as as-deposited 70 nm of Fe, an angle of
deposition of 70°, and an annealing temperature of 600 °C,
which showed a photocurrent density of 0.38 mA/cm
2
at 1.65
V vs reversible hydrogen electrode (RHE). Characterizations depicted
that this unique morphology with high crystallinity directly enhanced
the performance of hematite photoanodes. Further, deposition of 30
nm of cadmium (CdO) on the α-Fe
2
O
3
nanorods
produced a corn-like morphology with CdO nanoparticles (∼2
nm), resulting in 4-times enhancement of the PEC performance (1.2
mA/cm
2
at 1.65 V vs RHE). CdO acted as a co-catalyst, responsible
for satisfactory suppression of recombination and facilitating the
hole transfer, directly enhancing the overall photocurrent density.
This photoanode showed an extremely stable behavior over a period
of 26 h when kept under constant illumination. Furthermore, the CdO-modified
photoanode showed a better dye degradation (98% in 40 min) than the
bare hematite (60% in 40 min), proving to be an efficient photoanode.
To optimize the semiconductor properties of TiVO4 thin
films and enhance their performance, we incorporated cobalt nanoparticles
as an effective co-catalyst consisting of a non-noble metal. Through
an investigation into the impact of cobalt loading on spray pyrolyzed
TiVO4 thin films, we observed a significant enhancement
in the photoelectrochemical (PEC) performance. This was accomplished
by carefully optimizing the concentrations of Co2+ (3 mM)
to fabricate a composite electrode, resulting in a higher photocurrent
density for the TiVO4:Co photoanode. When an applied potential
of 1.23 V (vs RHE) was used, the photocurrent density reached 450
μA/cm2, approximately 5 times higher than that of
bare TiVO4. We conducted a thorough characterization of
the composite structure and optical properties. Additionally, electrochemical
impedance spectroscopy analysis indicated that the TiVO4/Co thin film exhibited a smaller semicircle, indicating a significant
improvement in charge transfer at the interface. In comparison to
bare TiVO4, the TiVO4/Co composite exhibited
a notable improvement in photocatalytic activity when degrading methylene
blue (MB) dye, a widely employed model dye. Under light illumination,
a TiVO4/Co thin film exhibited a notable dye degradation
rate of 97% within a 45 min duration. The scalability of our fabrication
method makes it suitable for large-area devices intended for sunlight-driven
PEC seawater splitting studies.
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