Localized Surface Plasmon Resonances of Various Nickel Sulfide Nanostructures and Au–Ni₃S₂ Core–Shell Nanoparticles

In this work, we investigate the occurrence of localized surface plasmon resonances (LSPRs) in different nickel sulfide nanostructures. Therefore, spherical and anisotropic nickel sulfide nanoparticles (NPs) are synthesized and analyzed regarding their optical properties by UV/vis/NIR and transient absorption spectroscopy. Furthermore, new pathways for the synthesis of spherical Ni 3 S 2 nanodots with an extremely narrow size distribution, as well as Au–Ni 3 S 2 core–shell NPs with controllable shell thickness, are presented. Our results show that NPs of different metallic nickel sulfide phases like Ni 3 S 2 and Ni 3 S 4 exhibit LSPR bands in the visible regime of the electromagnetic spectrum, which possibly makes them a comparably cheaper alternative to NPs consisting of noble metals like Au and Ag. In case of the presented plasmonic core–shell particles, the resonance frequency of the plasmon can be tuned between those of pure gold and pure Ni 3 S 2 NPs by varying the Ni 3 S 2 shell thickness.