SnO₂ and F doped SnO₂ (FTO) nanoparticles (NPs) have been synthesized by the hydrothermal method with subsequent annealing at 500 °C. The microstructure and photoluminescence (PL) property of SnO₂ and FTO NPs have been investigated, and an assumption model about the luminescence process of FTO NPs has been proposed. All of the SnO₂ and FTO NPs possess polycrystalline tetragonal rutile structures, and the average size in the range of 16.5–20.2 nm decreases with the increasing of F doping content. The doping element F is shown a uniformly distribution by electron energy loss spectroscopy (EELS) mapping. The oxygen vacancy concentration becomes higher as is verified by Raman and X-ray photoelectron spectra (XPS). There are three kinds of oxygen chemical states in SnO₂ and FTO NPs, in which O_α corresponds to oxygen vacancies. The room temperature PL position is observed to be independent of F doping content. F⁻ may substitute O²⁻ into the SnO₂ lattice by generating $F_O^{+}$ and one extra e⁻, which can combine with $V_O^{+}$ or $V_O^{++}$ to generate $V_O^0$ or $V_O^{+}$ to ensure charge balance.

Tin selenide (SnSe) compound has attracted much attention due to its unprecedented high ZT (∼2.6) in single crystals. The polycrystalline SnSe materials were then prepared to improve the mechanical performance for large-scaled application. However, the ZT values of 0.3–0.8 were much lower due to their poor electrical properties. In the present study, the zone melting method is employed to prepare the polycrystalline SnSe samples, which show highly textured structures and strong anisotropic thermoelectric performance. A maximum power factor (S²σ) of 9.8 μW cm⁻¹ K⁻² was obtained in the polycrystalline samples, which is comparable with that of SnSe single crystals, resulting in a peak ZT of 0.92 at 873 K. The zone-melted ingot was then pulverized into powders and the bulk material was prepared by the spark plasma sintering (SPS) technique. As a result, the ZT value was enhanced to be over 1.0, owing to the slight reduction of lattice thermal conductivity and maintenance of electrical performance. The present investigation indicates that the TE performance of the SnSe compound can be significantly improved by the texture modulation.

Colorimetric detection of glucose using enzyme-mimic nanoparticles (NPs) has been drawing great attention. However, many NPs lack good stability in solution, which results in reduced color change of substrates in colorimetric detection. Liner soluble macromolecules with high cationic density may be suitable candidates for the stabilization of NPs. Herein, we prepared polyethyleneimine-stabilized platinum NPs (Pt_n-PEI NPs) for colorimetric detection of glucose. The platinum NPs (Pt NPs) used in this system had small size (from 3.21 to 3.70 nm) and narrow size distribution. Pt₅₀-PEI NPs had high stability within one week with a hydrodynamic size of ∼25 nm and slightly positive zeta potential. Pt₅₀-PEI NPs-catalyzed oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H₂O₂, generating blue oxidized TMB (oxTMB), which indicated the peroxidase-like property of Pt₅₀-PEI NPs. The optimal condition for this reaction was pH = 4.0 at 30 °C. More importantly, Pt₅₀-PEI NPs were successfully used to detect glucose concentration by a colorimetric method with high selectivity. The established method had a linear concentration range from 10 to 5000 μM with a detection limit of 4.2 μM. For example, the concentration of glucose in saliva was tested to be 0.15 mM using our method. The high stability of Pt₅₀-PEI NPs enhanced the high accessibility of the active center of Pt NPs for substrates and consequent excellent catalytic property. This established method has great potential to be used in various applications for glucose detection in the future.