SnO2 Nanoflowers Research Articles

Microwave solvothermal synthesis of flower-like SnS2 and SnO2 nanostructures as high-rate anodes for lithium ion batteries

This paper reports a fast microwave-assisted solvothermal approach to fabricate flower-like SnS2 and SnO2 nanostructures. The synthetic conditions such as microwave-irradiation temperature, reaction time and precursor concentration are found to have critical influences on the product morphologies and sizes. When used as anode materials for rechargeable Li-ion batteries, flower-like SnO2 products exhibit better electrochemical properties than as-prepared flower-like SnS2 materials. A large reversible capacity of 717mAhg−1 is observed for SnO2 nanoflowers with a good cycliability at 100mAg−1. Moreover, SnO2 nanoflowers exhibit superior high-rate performances. Highly stable capacities of 667 and 532mAhg−1 are achieved at 1000mAg−1 and 2000mAg−1 respectively.

Hydrothermal synthesis of novel SnO2 nanoflowers and their gas-sensing properties

Self-assembly of one-dimensional nanoscale building blocks into functional 2D or 3D complex superstructures has stimulated a great deal of interest. In current work, using the hydrothermal method and reagent of hexamethylenetetramine (HMT), we synthesize the SnO2 3D hierarchical nanostructures with an average diameter of 200–400nm, which exhibit flower-like architectures assembled by numerous one-dimensional tetragonal prism nanorods. Further comparative studies demonstrate that the HMT provides nucleation sites for the assembling of the nanorods, which plays a crucial role in producing such unique flower-like architectures. Meantime, a novel growth mechanism is proposed in detail. In property, the prepared SnO2 nanoflowers show excellent gas-sensing performances to ethanol of 50ppm at an optimal temperature as low as 250°C. Such unique architectures may open up an avenue to further enhance the gas-sensing performances of SnO2 nanostructures for future sensor application.

Engineering of Facets, Band Structure, and Gas‐Sensing Properties of Hierarchical Sn2+‐Doped SnO2 Nanostructures

AbstractHierarchical SnO2 nanoflowers, assembled from single‐crystalline SnO2 nanosheets with high‐index (11$ \bar 3 $) and (10$ \bar 2 $) facets exposed, are prepared via a hydrothermal method using sodium fluoride as the morphology controlling agent. Formation of the 3D hierarchical architecture comprising of SnO2 nanosheets takes place via Ostwald ripening mechanism, with the growth orientation regulated by the adsorbate fluorine species. The use of Sn(II) precursor results in simultaneous Sn2+ self‐doping of SnO2 nanoflowers with tunable oxygen vacancy bandgap states. The latter further results in the shifting of semiconductor Fermi levels and extended absorption in the visible spectral range. With increased density of states of Sn2+‐doped SnO2 selective facets, this gives rise to enhanced interfacial charge transfer, that is, high sensing response, and selectivity towards oxidizing NO2 gas. The better gas sensing performance over (10$ \bar 2 $) compared to (11$ \bar 3 $) faceted SnO2 nanostructures is elucidated by surface energetic calculations and Bader analyses. This work highlights the possibility of simultaneous engineering of surface energetics and electronic properties of SnO2 based materials.

Template free synthesis of SnO2nanoflower arrays on Sn foil

The well aligned poppy-flower-like SnO2 nanoflower array on Sn-foil was successfully prepared by a simple solvothermal method without using any template or catalyst. The mixed solvent of aqueous sodium hydroxide and hydrazine hydrate plays a significant role for obtaining the crystalline pure SnO2 nanoflower array. Each petal of the nanoflower consists of the (110) plane of SnO2. The growth of the SnO2 nanoflowers has been described by the formation of layered Sn-hydrazine complexes. The surface defects and the oxygen vacancies of the SnO2 hierarchical nanoflowers are identified by Raman and electron paramagnetic resonance (EPR) spectroscopy and are analyzed in detail by steady state and time resolved photoluminescence spectra.

Porous SnO2 nanoflowers derived from tin sulfide precursors as high performance gas sensors

SnO2 has been confirmed to be a potential sensor to many toxic volatile gases. We report here the synthesis of porous SnO2 nanoflowers by in situ oxidization of SnS and SnS2 precursors with similar morphologies. The as-synthesized SnO2 products were characterized by FESEM, XRD, TEM, UV-vis spectrometry, fluorescence spectrometry and the nitrogen adsorption–desorption technique. Configured as resistor-type chemical sensors, the as-synthesized SnO2 products exhibited excellent sensitivity and fast response/recovery times towards different gases including ethanol, methanol, methanal and acetone. After Pt nanoparticles were loaded, their sensing properties were dramatically increased, indicating their promising applications in detecting toxic volatile organic materials.

Effective solar absorption and radial microchannels of SnO2 hierarchical structure for high photocatalytic activity

Photocatalytic removal of rhodamine B (RhB) and methyl orange (MO) has been studied using the hierarchical SnO2 nanoflowers and SnO2 nanorods under the simulated sunlight irradiation to investigate the influence of morphology on the photocatalytic activity. The hierarchical SnO2 nanoflower catalyst shows higher photocatalytic activity compared with SnO2 nanorod catalyst owing to its larger specific surface area and hierarchical structure, which can promote sunlight absorption and provide radial microchannels for reactant diffusion. The experiment also demonstrates a good photostability and reusability of the SnO2 nanoflower catalyst in photocatalystic degradation.

Pt support of multidimensional active sites and radial channels formed by SnO2 flower-like crystals for methanol and ethanol oxidation

SnO2 nanoflowers and nanorods have been synthesized by the hydrothermal method without using any capping agent. Both types of SnO2 nanostructures are selected as a support of Pt catalyst for methanol and ethanol electrooxidation. The synthesized SnO2 nanostructures and SnO2 supported platinum (Pt/SnO2) catalysts are characterized by X-ray diffraction, scanning electron microscope and high resolution transmission electron microscope. The electrocatalytic properties of the Pt/SnO2 and Pt/C catalysts for methanol and ethanol oxidation have been investigated systematically by typical electrochemical methods. The influence of SnO2 morphology on its electrocatalytic activity is comparatively investigated. The Pt/SnO2 flower-shaped catalyst shows higher electrocatalytic activity and better long-term cycle stability compared with other electrocatalysts owing to the multidimensional active sites and radial channels of liquid diffusion.