Photoelectrochemical (PEC) water
oxidation using ternary oxide
systems has been considered a promising approach for investigating
the effective utilization of sunlight and the production of green
fuel. Herein, we report a ternary-oxide-based CuWO4/BiVO4/FeCoO
x
film deposited entirely
by RF-magnetron sputtering using homemade ceramic targets. Our CuWO4/BiVO4 photoanode exhibits a significant photocurrent
density of 0.82 mA cm–2 at 1.23 V vs RHE under AM
1.5G illumination, which is a record 382% increase compared to that
of the bare CuWO4 film. To further boost the PEC performance,
we deposited an ultrathin layer of amorphous FeCoO
x
cocatalyst, resulting in a triple CuWO4/BiVO4/FeCoO
x
heterojunction with a
significant reduction in onset potential and a 500% increase in the
photocurrent density of bare CuWO4. Experimental and theoretical
approaches were used to provide insights into the interfacial band
alignment and photoinduced charge carrier pathway across heterojunctions.
Our results reveal noticeable interface potential barriers for charge
carriers at the CuWO4/BiVO4 heterojunction,
potentially limiting its application in tandem systems. Conversely,
the deposition of the FeCoO
x
ultrathin
layer over the CuWO4/BiVO4 heterojunction induces
a p–n junction on the BiVO4/FeCoO
x
interface, which, when
combined with the abundant FeCoO
x
oxygen
vacancies, results in improved charge separation and transport as
well as enhanced photoelectrochemical stability. Our study provides
a feasible strategy for producing photocatalytic heterojunction systems
and introduces simple tools for investigating interface effects on
photoinduced charge carrier pathways for PEC water splitting.
Low temperature processing of environmentally-friendly (K,Na)NbO 3and CoFe 2 O 4-based layered composites has been accomplished by hot pressing, and their electrical, piezoelectric and magnetoelectric properties have been characterized. High quality composite three-layer CoFe 2 O 4 /K 0.5 Na 0.5 NbO 3 /CoFe 2 O 4 structures with defect-free interfaces have been obtained by hot pressing at only 1000 o C, when highly reactive CoFe 2 O 4 powders obtained by Pechini are used. Negligible chemical reactions at, and interdiffusion across interfaces take place during the low temperature processing, while alkali volatilization is also minimized. Dense, crack-free
Magnetoelectric composites are an enabling material technology for a range of novel devices like electrically-tunable magnetic microwave components or room-temperature-operation high-sensitivity magnetic sensors. Among the different approaches under development, cofired ceramic layered composites provide large effective magnetoelectric coefficients and improved reliability. However, miniaturization and processing up-scaling remain an issue. This can be addressed by using tape casting technology to prepare multilayer structures, as it is industrially done for multilayer ceramic capacitors. We report here the processing of ceramic multilayer composites of environmentally-friendly piezoelectric (K 0.5 N a 0.5 ) 0.96 Li 0.04 N b 1−y T a y O 3 and magnetostrictive CoF e 1.75 M n 0.25 O 4 by water-based tape casting. Dense ceramic multilayers with high quality interfaces were obtained, and their func-
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