Extinction Coefficient of Plasmonic Nickel Sulfide Nanocrystals and Gold-Nickel Sulfide Core-Shell Nanoparticles

In the presented work, the molar extinction coefficient of plasmonic heazlewoodite (Ni3S2) nanoparticles and Au-Ni3S2 core-shell nanoparticles is determined for the first time. The results are compared to analogously determined extinction coefficients of pure Au nanocrystals (NCs), which themselves correlate very well with existing literature on the subject. The measured extinction coefficients at the localized surface plasmon resonance (LSPR) maximum wavelength of nickel sulfide particles are similar to the values of equally sized Au NCs. Therefore, considering the lower cost of the heazlewoodite material, it could be a reasonable alternative for optical applications of nanoparticles showing a LSPR in the visible regime of the electromagnetic spectrum. Furthermore, this study shows, that by growing a Ni3S2 shell onto a pure Au nanocrystal a highly tuneable optical material with variable LSPR frequency and molar extinction coefficient is obtained.