Three-dimensional (3D) nanostructures of metal oxides have been widely used for gas sensor devices. In this work, 3D porous SnO2 microstructures constructed by two-dimensional (2D) nanosheets were prepared via a simple hydrothermal process combined with subsequent annealing. Gold (Au) nanoparticles were successfully immobilized onto the surface of SnO2 nanosheets to serve as a sensitizer by a facile solution reduction process. This novel 3D Au/SnO2 microstructure has been investigated for gas senor and exhibits remarkably enhanced sensing performances to ethanol, e.g. high response, fast recovery time and good stability. The possible sensing mechanism is also discussed in terms of the special effect of Au functionalization.

Homogeneous TiO2@C composite nanospheres are synthesized by a direct pyrolysis strategy using Ti-containing organic–inorganic polymers as precursors. The TiO2@C composite nanospheres possess uniform distribution of tiny TiO2 nanoparticles confined in the carbon matrix with a homogeneous structure. The carbon phase can not only improve the conductivity but also prevent the aggregation of TiO2 nanoparticles. When evaluated as anodes for lithium-ion batteries, the TiO2@C nanocomposites demonstrate a high reversible specific capacity of 207 mA h g−1 at 0.5 C (1 C = 250 mA g−1) after 50 cycles and a stable cycling performance in comparison to pure TiO2 nanospheres. This work offers a new pathway for realization of carbon-based composite materials for use as high performance anodes in LIBs.

A facile reactive-template strategy has been developed to fabricate porous SnO2 nanotubes using MnO2 nanorods as the sacrificial template. The formation of nanotubes is based on the redox reaction mechanism, which requires no post-treatment of the MnO2 templates. The morphological and structural characteristics of the samples have been systematically characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal-gravimetric (TG), and N2 adsorption–desorption techniques. A gas-sensor device was constructed using as-prepared SnO2 nanotubes and was tested for its ability to detect ethanol and some other compounds. Because of the porous structure and relative large specific surface area, the SnO2 nanotube sensor manifests remarkably improved sensing performance, including fast response recovery, high sensitivity, and excellent repeatability, suggesting the promising application of the SnO2 nanotube materials.Keywords: gas sensor; high performance; nanotubes; porous; SnO2;

A facile one-pot strategy is developed to fabricate polypyrrole (PPy)/Au nanocomposites, in which Au nanoparticles with an average size of ca. 4.2 nm are uniformly dispersed on PPy. The morphology, structure, and composition of the products were characterized by transmission electronic microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and thermogravimetric analysis. Lysine plays a crucial role in the formation of uniform PPy/Au nanocomposites. Importantly, the PPy/Au nanocomposites have demonstrated great potential for detecting ammonia gas at room temperature, showing enhanced sensor performances in comparison to pure PPy as a result of the funtionalization of Au nanoparticles on PPy. The possible sensing mechanism is also discussed.