Surface-enhanced spectroscopy techniques are the method-of-choice to
characterize adsorbed intermediates occurring during electrochemical reactions,
which are crucial in realizing a green sustainable future. Characterizing
species with low coverages or short lifetimes have so far been limited by low
signal enhancement. Recently, metasurface-driven surface-enhanced infrared
absorption spectroscopy (SEIRAS) has been pioneered as a promising narrowband
technology to study single vibrational modes of electrochemical interfaces
during CO oxidation. However, many reactions involve several species or
configurations of adsorption that need to be monitored simultaneously requiring
reproducible and broadband sensing platforms to provide a clear understanding
of the underlying electrochemical processes. Here, we experimentally realize
multi-band metasurface-driven SEIRAS for the in-situ study of electrochemical
CO2 reduction on a Pt surface. We develop an easily reproducible and
spectrally-tunable platinum nano-slot metasurface. Two CO adsorption
configurations at 2030 cm-1 and 1840 cm-1 are locally enhanced as a proof of
concept that can be extended to more vibrational bands. Our platform provides a
41-fold enhancement in the detection of characteristic absorption signals
compared to conventional broadband electrochemically roughened platinum films.
A straightforward methodology is outlined starting by baselining our system in
CO saturated environment and clearly detecting both configurations of
adsorption, in particular the hitherto hardly detectable CO bridge
configuration. Then, thanks to the signal enhancement provided by our platform,
we find that the CO bridge configuration on platinum does not play a
significant role during CO2 reduction in an alkaline environment. We anticipate
that our technology will guide researchers in developing similar sensing
platforms.Comment: 21 pages, 4 figure