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A new type of nonspherical yolk-shell structures in the case of SnO 2 has been successfully prepared by a simple anneal-etching strategy without employing any additional templates or capping agents. The morphological and structural characterization reveals that SnO 2 yolk-shell particles have a hierarchical architecture with penetrable multi-walled surfaces and cuboctahedral shape, where the secondary building blocks are numerous nanoparticles. The synthetic step-dependent evolution process of SnO 2 yolk-shell cuboctahedra is investigated and the possible formation mechanism is also discussed. To demonstrate the merit of unique structure for the fast mass transfer, sensor based on SnO 2 products has been fabricated and the results exhibit excellent sensing performances for toluene detection. It is found that our SnO 2 yolk-shell structures have a response of 28.6–20 ppm toluene at the optimal working temperature of 250 °C, and the response time and recovery time are within 1.8 and 4.1 s, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Cubic ZnSnO3 nanocages, a geometrical cube-shape with a hierarchical structure composed of small nanoparticles as secondary units, are successfully synthesized via a facile hydrothermal process. These ZnSnO3 nanocages have hollow interiors and good-permeation surfaces, and are used for detecting different gases such as ethanol (C2H5OH), formaldehyde (HCHO), and hydrogen sulfide (H2S). These ZnSnO3 nanocages show good response, selectivity, response and recovery characteristics to H2S. It is found that ZnSnO3 nanocages have a response of 17.6–50ppm H2S at the optimal operating temperature of 310°C and the response time is shorter than 20s. [Copyright &y& Elsevier]

Abstract: We report the synthesis of flowerlike ZnO nanostructure using a facile hydrothermal process, and the investigation on the ammonia (NH3)-sensing properties of the pure and palladium (Pd)-sensitized flowerlike ZnO nanostructure. The phase purity, morphology, and structure of the pure and Pd-sensitized ZnO nanostructure are investigated. The characterized results reveal that the flowerlike ZnO has a wurtzite structure and is composed of numerous aggregated single-crystalline ZnO nanorods with a diameter of about 60nm. Having fabricated gas sensors based on the pure and Pd-sensitized flowerlike ZnO, we find that the Pd-sensitized sensor exhibits a response of 45.7–50ppm NH3 at 210°C, which is about 8 times higher than that of pure ZnO at the optimal operating temperature of 350°C. The enhanced NH3-sensing performance demonstrates that the significant decrease in optimal operating temperature and the distinct increase in response are attributed to the sensitization effect of Pd. [Copyright &y& Elsevier]