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

Abstract

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, energydispersive 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.

Type-II Heterojunctions in SnO2-Coated TiO2 Core-Shell Nanoparticles

“…The TEM images in Figure 5a and 5b shows the SnO 2 shell comprised of minute polycrystallites. This polycrystalline porous nature of the shell is consistent with SnO 2 synthesized using the sodium stannate method [23][24]27]. The TEM image in Figure 5a also confirmed that the formation of free SnO 2 nanoparticles was limited.…”

“…After the successful synthesis of the TiO 2 NPs, tin oxide shells were grown around these nanoparticles, as outlined in Scheme 1. The synthesis strategy to grow the SnO 2 shells is loosely based on the method reported by Medhi et al [23]. The SnO 2 shells were formed by using an aqueous sodium stannate trihydrate precursor solution.…”

“…Although the number of free SnO 2 NPs decreased, there was still no significant shell growth on the surface of the TiO 2 NPs (see Figure 1d). Typically, in previous studies with metal nanoparticle cores, sodium stannate has been added in a single injection [23,27]. The sodium stannate has been observed to preferentially crystallize as SnO 2 on the surface of Au NPs.…”

“…Hydrothermal treatment is a standard procedure to achieve anatase phase TiO 2 [30]. Interestingly, the SnO 2 shells grown atop the anatase TiO 2 layer adopt the rutile phase [23][24]. The (110), (101), and (211) peaks observed for the nanoparticles with a SnO 2 coating at 2θ = 26.28, 33.71, and 58.51 are characteristic of SnO 2 nanoparticles prepared using this method [23][24].…”

Tuning Cu2O Shell on Gold Nanocube Core Employing Amine-Functionalized Silane for Electrocatalytic Nitrite Detection

“…In the past few decades, the synthesis of single-component noble metal and metal oxide heterostructures has attracted great attention due to their unique size, shape, and composition-controlled properties and their applications in catalysis, sensors, and photonics. − Recently, the combination of noble metals such as Au, Ag, and metal oxides, in particular Cu 2 O, in the form of core–shell nanomaterials has been reported. , Among the metals, Au has attracted greater attention due to its chemical stability and applications in various fields such as catalysis, sensors, and biomedical engineering. − Au nanostructures with different shapes exhibit interesting optical and sensing properties, and particularly the morphology of gold nanocubes (AuNCs) is interesting because various other shapes can be prepared from the AuNC core. − The pristine Au core shows good catalytic activity, which can further be enhanced by synthesizing core–shell NPs of Au as a core and metal oxide as a shell. The enhanced catalytic activity of core–shell nanostructures is observed due to the combination of metal and metal oxide .…”