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Abstract: The hierarchical unloaded and Pd-loaded SnO2 nanostructures, consisting of many aggregative nanorods were prepared by one-step hydrothermal method. A possible formation mechanism of these hierarchical structures was proposed. The butanone sensing properties of the sensors based on unloaded and hierarchical Pd-loaded SnO2 nanorods were investigated. The results indicate that the response of sensor using hierarchical Pd-loaded SnO2 nanorods to 1000ppm butanone was 451 at 250°C, which was about 10 times higher than that of sensor based on unloaded SnO2. Such enhanced gas sensing performances can be attributed to both the chemical and the electrical contribution of Pd loading. [Copyright &y& Elsevier]

Abstract: Novel metal palladium was loaded on γ-Al2O3 using decompression distillation, ultrasonic impregnation, and isometric impregnation. Of these loading methods, isometric impregnation was examined to be the best method for preparing high-performance Pd/Al2O3 catalysts. The observation with transmission electron microscopy demonstrated that Pd nanorods were formed on γ-Al2O3 for the samples preparing with isometric impregnation. The correlation of the morphology of Pd with the loading time was also investigated: Pd catalysts loaded for 2 and 6h had the almost same nanorod morphology and relatively uniform size. Nitrogen adsorption and desorption isotherms indicate that Pd nanorods increased the BET-specific surface area of Pd/γ-Al2O3. The catalytic combustion gas sensor prepared using Pd/γ-Al2O3 via isometric impregnation exhibited high sensitivity to methane as well as fast response and recovery properties. [Copyright &y& Elsevier]

Abstract: ZnO/SnO2 composite materials are synthesized by hydrolyzing SnCl2 on ZnO nanorods via the wet chemical method. The gas sensing studies revealed that ZnO/SnO2 exhibits a high response to NO2 at room temperature under UV light emitting diode illumination. The highest response to NO2 was achieved by the ZnO/SnO2 composite with Zn and Sn molar ratio of 1:1 (ZS3). The resistance of sensor based on ZS3 with UV light stimulation changed 1266-fold to 500ppb NO2 gas at room temperature. Furthermore, the selectivity, as well as response and recovery properties, of the sensor was improved remarkably by UV light irradiation. The ZnO/SnO2 heterojunction model and the increased photo-generated electrons are proposed to elucidate the gas sensing mechanism. [Copyright &y& Elsevier]