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The Pd nanoparticles decorated hollow SnO 2 nanofibers (NFs) were synthesized by the electrospinning technique and the wet decorating process. The properties of the sensing material were characterized by X-Ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Compared with the pure SnO 2 NFs gas sensor, the optimum operating temperature of Pd decorated hollow SnO 2 NFs gas sensor dropped to 160 °C from 180 °C. The response to 100 ppm formaldehyde (HCHO) was raised to 18.8 from 5.4. Furthermore, the response-recovery characteristics were enhanced a lot. It is believed that its high gas sensing performance is derived from the hollow structure and the catalysis of Pd nanoparticles. [ABSTRACT FROM AUTHOR]

As a most promising low-cost substitute for the current lithium-ion batteries technology, sodium-ion batteries (SIBs) have aroused particular attentions over the past few years. However, the performance of SIBs is still far from our expectations due to the lack of suitable electrode materials with excellent electrical conductivity, high energy density, long-term cycling stability, and high-rate performance. Herein, ultrafine ZnSe nanoparticles homogeneously confined within N,Se-codoped carbon matrix were constructed via a facile solid state reaction route. By directly using zinc acetate dihydrate, o -vanillin and o -phenylenediamine as starting raw materials, a self-assembly solid state reaction occurred to give rise to a bis-Schiff base complex with zinc (II) at room temperature. After subsequent calcination in the presence of selenium powder at elevated temperature, simultaneous carbonization and selenization took place, resulting to the in-situ formation of ultrafine ZnSe nanoparticles (∼6.5 nm) encapsulated in N,Se-codoped carbon matrix (named as ZnSe⊂NSeC). The unique ZnSe⊂NSeC hybrid demonstrated an impressive sodium storage performance in terms of long-term cycling stability (282 mA h g−1 of charging capacity after 500 cycles at 0.1 A g−1) and excellent rate capability (198 mA h g−1 of charging capacity at 5 A g−1). More importantly, a superb stable charging capacity of 238 mA h g−1 still maintained even after 1200 cycles at 1.0 A g−1. Such strategy may also be used to explore other nanocomposites to boost their energy storage performance. • The ZnSe⊂NSeC hybrid was readily in-situ fabricated via ambient temperature solid state reaction followed by subsequent calcination. • Ultrafine ZnSe NPs were evenly encapsulated in the N,Se-codoped carbon matrix in the ZnSe⊂NSeC hybrid before and after prolonged charge/discharge cycles. • The ZnSe⊂NSeC hybrid exhibited exceptional electrochemical performance for sodium storage. [ABSTRACT FROM AUTHOR]

Abstract: Up-conversion nanoparticles (UCNPs), which can convert a longer wavelength radiation to a shorter wavelength radiation, have great potential use as bio-labels in biological detection. However, these NPs usually cannot be used directly unless their surface is further modified. Herein, we developed a novel and straightforward method for the synthesis of monodisperse NaYF4:Yb,Er/Polymer UCNPs. The resultant UCNPs exhibited a pure hexagonal phase, strong UC fluorescent intensity, and a uniform size of about 40nm, which were characterized by XRD, luminescence spectroscopy and TEM, respectively. FT-IR spectra revealed that these NPs were coated with a layer of hydrophilic polymers (including PVP, PEG, PAA and PEI), thus the NPs could be dispersed in water easily. More importantly, the PAA and PEI coated NPs were functionalized by –COOH and –NH2 groups, respectively, which were expected to be used for further bio-conjugation. [Copyright &y& Elsevier]