posted on 2022-01-19, 19:37authored byLuc Driencourt, Benjamin Gallinet
Plasmonic effects have been considered
as a promising way of bringing
the performances of metal oxide water splitting photoelectrodes closer
to their theoretical limit. Optimizing the contribution of plasmonic
effects is far more complex than material selection and needs to include,
in particular, morphological aspects. In this work, we establish practical
design guidelines for enhancing the performances of metal oxide photoanodes
with plasmonic nanoparticles. A previously reported theoretical method
modeling the contribution of optical nanostructures is used to calculate
the photoelectrochemical performances (photocurrent, external quantum
efficiency) and experimentally validated on fabricated devices. New
insights on the contribution of plasmonic nanoparticles are found.
Specifically, the performances are strongly influenced by the illumination
direction, the active material morphology, and the size and position
of the plasmonic scatterers. The light intensity distribution is studied
to understand how plasmonic nanoparticles are modifying the light
absorption in the active material. It is revealed that near-field
hot-spots, exponentially decreasing with the distance to the scatterers,
can beneficially impact the performances only for pure nanoparticles
whereas interference effects are contributing even when the nanoparticles
are covered with a protective shell (e.g., SiO2).