ABSTRACT
Ammonium sulfide ((NH4)2S) exhibits high reactivity as a sulfide reagent in anion exchange reactions that transform CoO to cobalt sulfide nanoparticles (NPs). The faster diffusion of Co(2+) and O(2-) than the incoming S(2-) during the anion exchange causes a significant expansion of the NP voids. The low temperature (70 °C) anion exchange reaction produces amorphous cobalt sulfide NPs with Co : S ratio of ca. 3 : 4, which are converted into crystalline NPs with a major phase of cubic Co3S4 by annealing at high temperature in an organic solution.
ABSTRACT
The layer-by-layer processing of Au/Au(x)Pd(1-x) core/alloy nanoparticles via microwave irradiation (MWI) based hydrothermal heating is described. Alloy shell growth was monitored by the attenuation of surface plasmon resonance (SPR) as a function of shell thickness and composition. Discrete dipole approximation (DDA) correlated the SPR to particle morphology.
