Synthesis of porous flower-like SnO_(2)/CdSnO_(3) microstructures with excellent sensing performances for volatile organic compounds

Porous flower-like SnO_(2)/CdSnO_(3) microstructures self-assembled by uniform nanosheets were synthesized using a hydrothermal process followed by calcination,and the sensing performance was measured when a gas sensor,based on such microstructures,was exposed to various volatile organic compound(VOC)gases.The response value was found to reach as high as 100.1 when the SnO_(2)/CdSnO_(3) sensor was used to detect 100 ppm formaldehyde gas,much larger than those of other tested VOC gases,indicating the high gas sensitivity possessed by this sensor especially in the detection of formaldehyde gas.Meanwhile,the response/recovery process was fast with the response time and recovery time of only 13 and 21 s,respectively.The excellent gas sensing performance derive from the advantages of SnO_(2)/CdSnO_(3),such as abundant n-n heterojunctions built at the interface,high available specific surface area,abundant porosity,large pore size,and rich reactive oxygen species,as well as joint effects arising from SnO_(2) and CdSnO_(3),suggesting that such porous flower-like SnO_(2)/CdSnO_(3) microstructures composed of nanosheets have a high potential for developing gas sensors.

Preparation of porous sea-urchin-like CuO/ZnO composite nanostructure consisting of numerous nanowires with improved gas-sensing performance

A sea-urchin-like CuO/ZnO porous nanostructure is obtained via a simple solution method followed by a calcination process.There are abundant pores among the resulting nanowires due to the thermal decomposition of copper-zinc hydroxide carbonate.The specific surface area of the as-prepared CuO/ZnO sample is determined as 31.3 m^(2)·g^(-1).The gas-sensing performance of the sea-urchin-like CuO/ZnO sensor is studied by exposure to volatile organic compound(VOC)vapors.With contrast to a pure porous sea-urchin-like ZnO sensor,the sea-urchin-like CuO/ZnO sensor shows superior gas-sensing behavior for acetone,formaldehyde,methanol,toluene,isopropanol and ethanol.It exhibits a high response of 52.6-100 ppm acetone vapor,with short response/recovery time.This superior sensing behavior is mainly ascribed to the porous nanowireassembled structure with abundant p-n heterojunctions.

Synthesis of porous TiO2 nanowires and their photocatalytic properties

Porous titanium dioxide （ZiO2） nanowires were synthesized via a surfactant-free hydrothermal method followed by acid-washing process and calcination. The structures and morphologies of products were characterized by field emission scanning electron micro- scopy （FESEM）, Transmission electron microscopy （TEM）, X-ray diffraction （XRD）, and Brunauer-Emmett- Teller （BET） N2 adsorption-desorption analyses. The analysis of FESEM suggested the precursor was composed of a vast of uniform nanostructures like wires. The nanowire-like precursor was transformed into the porous nanowire after acid-treatment and calcination at 500~C for 2 h in air. The surface area of as-synthesized TiO2 nanowires calculated by BET is 86.4 m2/g. Furthermore, the photocatalytic properties of synthesized porous TiO2 nanowires were evaluated through the degradation of methylene blue （MB） and Rhodamine B （RhB）. The results clearly suggested that the as-prepared porous TiO2 nanowires showed remarkable photocatalytic performance on the degradation of RhB and MB due to their small size of nanocrystallites and the porous naonstructure.