Antimony- and Zinc-Doped Tin Oxide Shells Coated on Gold Nanoparticles and Gold-Silver Nanoshells Having Tunable Extinctions for Sensing and Photonic Applications

This paper reports the synthesis and study of doped metal oxides as the shell in core-shell nanoparticle architectures. Specifically, the paper describes the synthesis of gold nanoparticles (Au NPs) and gold-silver nanoshells (GS-NSs) coated with antimony- and zinc-doped tin oxide (SnO2) shells (i.e., Au@ATO, Au@ZTO, GS-NS@ATO, and GS-NS@ZTO) with a comparison to the undoped SnO2-coated analogues Au@SnO2 and GS-NS@SnO2. The doped tin oxide core-shell nanoparticles prepared here were thoroughly characterized using scanning electron microscopy, transmission electron microscopy, dynamic light scattering, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Separately, their optical properties were evaluated by UV-vis and photoluminescence spectroscopy. The results demonstrate that noble-metal nanoparticles such as Au NPs and GS-NSs, which exhibit strong surface plasmon resonances at visible-to-near-IR wavelengths, can be activated across a broader region of the solar spectrum when used in conjunction with wideband-gap semiconductors. In particular, utilization of a GS-NS core induces near-complete suppression in the electron-hole recombination processes in the tin oxide materials. Potential impacts on sensing and photonic applications are highlighted.