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 (SnO 2 ) shells (i.e., Au@ATO, Au@ZTO, GS-NS@ATO, and GS-NS@ZTO) with a comparison to the undoped SnO 2 -coated analogues Au@SnO 2 and GS-NS@SnO 2 . 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 wide-band-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.