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Pd-loaded SnO 2 hollow microspheres have been successfully prepared via a facile one-pot hydrothermal route and subsequent Pd-loaded treatment without involving any templates, surfactants, or capping agents. The morphological and structural characterization confirms that Pd-loaded SnO 2 hollow microspheres are hierarchically constructed of numerous well-aligned rodlike SnO 2 subunits with ultrathin diameter of about 5–10 nm and monodisperse Pd particles with several nanometers in size. The time-dependent investigation demonstrates that the formation of hierarchical SnO 2 hollow spheres is driven by Ostwald-ripening mechanism. Furthermore, gas sensors based on pure and Pd-loaded SnO 2 have been fabricated. The Pd-loaded SnO 2 hollow microspheres exhibit relatively lower operating temperature, higher response and selectivity to toluene in comparison with that of pure SnO 2 . Besides structural merits of ultrathin nanorod-assembled hollow and porous structure, the promotion of sensing performances can also be attributed to the contribution of catalytic Pd particles. [ABSTRACT FROM AUTHOR]

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]

The designed preparation of pure and Au-loaded SnO 2 hollow multilayered nanosheets for CO detection has been realized via a rational combination of different purposeful multi-step synthetic route. The synthetic step-dependent shape and structure evolution has been investigated and the formation mechanism for the unique hollow nanosheets is also discussed. The characterized results confirm that flowerlike SnO 2 nanosheets with a polycrystalline rutile structure are assembled from hexagonal mesoporous and multilayered walls, which can further be subdivided into SnO 2 nanoparticles as structural subunits. Furthermore, gas sensors based on the as-prepared pure and Au-loaded SnO 2 have also been fabricated. The Au-loaded SnO 2 hollow nanosheets show significantly lower working temperature, faster response-recovery and improved selectivity to CO in comparison with that of pure SnO 2 . Besides structural merits including hollow and easily penetrated multilayered walls, which facilitate the transport rate and augment the adsorption quantity of gas molecule, the significant improvement of the sensing properties is also attributed to the catalytic effect of Au. [ABSTRACT FROM AUTHOR]

The unique flowerlike SnO 2 hollow nanosheets with multilayer walls have been successfully synthesized by a simple anneal-etching strategy based on flowerlike ZnSn(OH) 6 solid nanosheets. FESEM and TEM observations reveal that this new type of nonspherical SnO 2 hollow structure is composed of hexagonal hollow nanosheets with mesoporous and multilayered interiors, where the secondary building blocks are numerous nanoparticles. Synthetic step-related investigation demonstrates that the formation of flowerlike hollow nanosheets with mesoporous and multilayer walls are ascribed to the final well-preserved shapes of flowerlike ZnSn(OH) 6 solid template and the critical hollowing process in the last etching treatment. The well-aligned porous and multilayer walls of SnO 2 hollow nanosheets retain actual high surface area and surface accessibility, and the improved gas sensing performances can be anticipated. It is found that our SnO 2 nanostructures have a response of 18.3–50 ppm acetone at the optimal working temperature of 300 °C, and the response time and recovery time are within 0.9 and 5.8 s, respectively. [ABSTRACT FROM AUTHOR]