National Synchrotron Radiation Facility

China

National Synchrotron Radiation Facility

China

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Ma M.,Beihang University | Ma M.,Langfang Teachers College | Pan Z.,National Synchrotron Radiation Facility | Wang W.,Tsinghua University | And 5 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2013

We report the microstructure, gas-sensing properties of the ordered mesoporous Co3O4 prepared by modified KIT-6 template method. Highly ordered mesoporous nanostructures of the as-prepared products have been characterized by X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), high-resolution transmission electron microscopy (HRTEM) and N2 adsorption/ desorption analysis. We find that the ordered mesoporous Co3O4 enables a significant improvement of sensor response and selectivity to ethanol, which demonstrates the potential use of the ordered mesoporous Co3O4 as alcohol gas-sensing material. Through the analysis of microstructure including HRTEM and N 2 adsorption/desorption, the sensing properties for the ordered mesoporous Co3O4 can be attributed qualitatively to its large specific surface area and porous morphology. Moreover, the results of EXAFS illustrate that the disorder degree and unsaturated bond of the ordered mesoporous Co3O4 increase, which agree well with the results observed in gas sensors. This makes the nanostructured ordered mesoporous Co3O4 a promising sensor material for detecting the alcohol gas. Copyright © 2013 American Scientific Publishers All rights reserved.


Cheng Y.,CAS Fujian Institute of Research on the Structure of Matter | Yan F.,CAS Fujian Institute of Research on the Structure of Matter | Huang F.,CAS Fujian Institute of Research on the Structure of Matter | Chu W.,National Synchrotron Radiation Facility | And 9 more authors.
Environmental Science and Technology | Year: 2010

Bioremediation of Cr(VI) through reduction relies on the notion that the produced Cr(III) may be precipitated or ef?ciently immobilized. However, recent reports suggest that soluble organo-Cr(III) complexes are present in various chromate-reducing bacterial systems. This work was designed to explore the factors that affect the immobilization of Cr(III) in the Ochrobactrum anthropi system. X-ray absorption ?ne structure analysis on the cell debris clearly veri?ed that coordination of Cr(III) occurs on the surfaces via the chelating coordination with carboxyl- and amido-functional groups. However, competitive coordination experiments of Cr(III) revealed that the small molecules such as amino acids and their derivatives or multicarboxyl compounds hold stronger coordination ability with Cr(III) than with cell debris. We speculate that it is the preferential coordination of Cr(III) to the soluble organic molecules in the bacterial culture medium that inhibits effective immobilization of Cr(III) on the cells. On the basis of this understanding, a strategy with two-step control of the medium was proposed, and this achieved successful immobilization of Cr(VI) as Cr(III) by O. anthropi and Planococcus citreus in 5 50 L pilot-scale experiments. © 2010 American Chemical Society.

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