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Optimization of Au:CuO Nanocomposite Thin Films for Gas Sensing with High-Resolution Localized Surface Plasmon Resonance Spectroscopy
journal contribution
posted on 2020-02-25, 21:13 authored by Manuela Proença, Marco Sampaio Rodrigues, Joel Borges, Filipe VazGas
sensing based on bulk refractive index (RI) changes, has been
a challenging task for localized surface plasmon resonance (LSPR)
spectroscopy, presenting only a limited number of reports in this
field. In this work, it is demonstrated that a plasmonic thin film
composed of Au nanoparticles embedded in a CuO matrix can be used
to detect small changes (as low as 6 × 10–5 RIU) in bulk RI of gases at room temperature, using a high-resolution
LSPR spectroscopy system. To optimize the film’s surface, a
simple Ar plasma treatment revealed to be enough to remove the top
layers of the film and to partially expose the embedded nanoparticles,
and thus enhance the film’s gas sensing capabilities. The treated
sample exhibits high sensitivity to inert gases (Ar, N2), presenting a refractive index sensitivity (RIS) to bulk RI changes
of 425 nm/RIU. Furthermore, a 2-fold signal increase is observed for
O2, showing that the film is clearly more sensitive to
this gas due to its oxidizing nature. The results showed that the
Au:CuO thin film system is a RI sensitive platform able to detect
inert gases, which can be more sensitive to detect noninert gases
as O2 or even other reactive species.