The interaction of incident light with noble metal nanoparticles
engenders a fascinating phenomenon known as localized surface plasmon
resonance (LSPR). This results in the presence of single or multiple
intense absorption bands in the visible to near-infrared spectral
range whose position is affected by the refractive index of the surrounding
medium. In this comprehensive study, we thoroughly investigated the
experimental parameters governing the size, aspect ratio, and optical
properties of hollow gold nanoshells (hAuNSs) synthesized through
the galvanic exchange of cobalt-based nanospheres. Subsequently, we
rigorously determined both the empirical and the theoretical refractive
index sensitivity (RIS) and figure of merit (FoM) of these engineered
nanostructures. Notably, hAuNS with an external diameter of 98 nm
and a shell thickness of 13 nm demonstrated a noteworthy RIS of 360
nm/RIU and an FoM of 2.0 in solution. In contrast, solid gold nanospheres
(sAuNSs) of a similar diameter exhibited a significantly lower RIS
of 136 nm/RIU. Following the transfer of both of these nanostructures
onto glass slides for the development of LSPR sensors, it was intriguing
to note that the RIS and FoM remained largely unaffected. These findings
underscore the potential of these plasmonic nanoparticles as promising
candidates for the design of sensitive solid-phase LSPR sensing devices
