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Xu Q.-F.,Shanghai JiaoTong University | Wang J.-N.,Shanghai Key Laboratory for Metallic Functional Materials
Frontiers of Materials Science in China

Superhydrophobic and transparent coatings have been prepared by self-assembly of dual-sized silica particles from a mixed dispersion. The desirable micro/nano hierarchical structure for superhydrophobicity is constructed simply by adjusting the size and ratio of the dual-sized particles without organic/inorganic templates. The transparency of the prepared coatings is also researched, and the light scattering can be reduced by lowering the ratio of big sub-micro particles while the superhydrophobicity maintains unchanged. When nano particles with a diameter of 50 nm and sub-micro particles with a diameter of 350 nm are assembled, a superhydrophobic property with a water contact angle of 161° is achieved. Additionally, the coated glass is also very transparent. The highest transmittance of the coated glass can reach 85%. Compared to traditional colloid self-assembly approach, which often involves dozens of steps of layer-by-layer processing and organic/inorganic templates, the present approach is much simpler and has advantages for large-scale coating. © 2010 Higher Education Press and Springer-Verlag Berlin Heidelberg. Source

Niu J.J.,Shanghai JiaoTong University | Wang J.N.,Shanghai Key Laboratory for Metallic Functional Materials
Acta Materialia

The dependence on temperature and structure of the electrochemical activity of a catalyst supported on hollow carbon nanocages (HCNCs) with large scales (>5 g h-1) by a simple N2-bubbling floating method is discussed. The effect of gas flow on an HCNC-supported catalyst was systematically studied in our previous work. Here we specify the electrocatalytic activity of the samples with different temperatures and graphite structures under 900 and 1000 °C by cyclic voltammograms. The peak current density of H2-adsorption/desorption is four times higher than that of the commercial Pt/C (Vulcan XC-72). Besides the comparison with commercial carbon, the fuel cell performance was measured. The single fuel cell test for Pt/HCNCs showed a high turn-on voltage of 0.9 V and a relatively high power density of 0.13 W cm-2 under a low temperature of 60 °C and a low gas pressure of 1 atm. © 2009 Acta Materialia Inc. Source

Xu Q.F.,Shanghai JiaoTong University | Wang J.N.,Shanghai Key Laboratory for Metallic Functional Materials | Sanderson K.D.,Pilkington Group Ltd
ACS Nano

Superhydrophobic, highly transparent, and stable organic-inorganic composite nanocoating is successfully prepared by a simple sol-gel dip-coating method. This method involves control of the aggregation of inorganic colloid particles by polymerization and ultrasonic vibration to create the desired micro/nanostructure in the coating. Superhydrophobicity and transparency of the coating can be controlled by adjusting the initial concentration of monomer and the size of aggregates in the sol-gel. Thus, superhydrophobicity and high transparency can be concurrently achieved in a single coating. The prepared coating also possesses good thermal stability. Its superhydrophobicity can be maintained from 20 to 90 °C. © 2010 American Chemical Society. Source

Paiva M.C.,University of Minho | Xu W.,University of Aarhus | Xu W.,Shanghai Key Laboratory for Metallic Functional Materials | Fernanda Proenca M.,University of Minho | And 3 more authors.
Nano Letters

Carbon nanotubes (CNTs), functionalized by a cycloaddition reaction, were studied by ultrahigh vacuum scanning tunneling microscopy (STM). The STM images provided evidence for partial or total unzipping of the outer CNT layer. The formation of graphene ribbons was triggered by the STM tip, under specific operating conditions. A model for the unzipping is proposed, based on the perturbation of the φ-conjugation along the CNT surface induced by the cycloaddition reaction. © 2010 American Chemical Society. Source

Ma J.,Tongji University | Ma J.,Shanghai JiaoTong University | Yu F.,Shanghai JiaoTong University | Wang J.N.,Shanghai Key Laboratory for Metallic Functional Materials
Journal of Materials Chemistry

A simple freeze-smashing method is described to produce water-dispersible single-walled carbon nanotubes (SWCNTs). This is based on freezing SWCNTs in ice and then smashing it in a crusher. After the smashing process, SWCNTs are found to be dispersible in water without any addition of dispersant and destruction of the good graphitic structure. When such SWCNTs are used as a catalyst support for fuel cells, they show much better performance than the original SWCNTs, multi-walled carbon nanotubes and the commercial catalyst from Johnson Matthey Company as well. It is suggested that the present approach might be useful for preparation of water-dispersible single-walled carbon nanotubes in wide areas such as information technology, biomedicine, environmental and energy industries. © The Royal Society of Chemistry 2010. Source

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