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Li W.,Wuxi Shunye Technology Co. | Yang L.-L.,Wuxi Shunye Technology Co. | Lin B.,Huainan Normal University | Isimjan T.T.,Wuxi Shunye Technology Co. | And 4 more authors.
Materials Research Express | Year: 2015

Asimple process is reported of the large-scale synthesis of microspherical mixed phase α-and β-Ni (OH)2 nanofibers produced by precipitation from aqueous NiCl2-NH4OH. These microspheres, with diameters of 20-50 μm, are composed of three-dimensional, nanoporous nanofibers, oriented along the radial direction. The nanofibers have lengths of 300-1000 nm, diameters of 30-50 nmand a specific surface area of 286.4m2 g-1. The effects of temperature and concentration on the morphology of the products were studied systematically, and the nanofiber growth mechanism was investigated. It was found that the nanostructure of Ni(OH)2 could be changed from microspheres to nanoflakes, to nanofibers and nanoparticles, as the NiCl2 concentration is increased from 2 to 8 M, and forNH4OH concentrations from 10 to 14 M. The as-synthesized nanofibers exhibit excellent charge-discharge performance and the highest yet capacitance of 1271 F g-1 for electrochemical supercapacitors, which is much higher than β-Ni(OH)2 nanoplates (797 F g-1) and commercial Ni(OH)2 powder (529.4 F g-1) at 1 A g-1 current density. The results indicate that as-synthesized hierarchical nanofibers, composed of mixed α-and β-Ni(OH)2 phases, are an excellent candidate for energy storage applications. The large-scale commercialization of our laboratory-produced nanofibers is also discussed. © 2015 IOP Publishing Ltd. Source

Wan F.,Wuxi Shunye Technology Co. | Yang D.-Q.,Wuxi Shunye Technology Co. | Sacher E.,Ecole Polytechnique de Montreal
Journal of Materials Chemistry A | Year: 2015

Superhydrophobic (SH) surfaces generally refer to those having a static water contact angle larger than 150° and a slide angle less than 10°, when both the surface and the water droplet are at room temperature. Most such surfaces lose superhydrophobicity when exposed to hot (e.g., >55 °C) water. Our recently published results (Z. J. Yu, J. Y. Yang, W. Fang, Q. Ge, L.-L. Yang, Z.-L. Ding, D.-Q. Yang, E. Sacher and T. T. Isimjan, Journal of Materials Chemistry A, 2014, 2 10639) indicated that hot water superhydrophobicity is maintained when the SH surface temperature is higher than that of the water droplet. Here, we find that carbon nanotubes (CNTs) can be developed into SH surface coatings that repel hot water without any limitation to the surface temperature. Our SEM observations demonstrate that nanostructures formed by CNTs, contributing both a high porosity and a small water droplet contact area, will maintain superhydrophobicity even for hot water. In particular, a composite, made of CNTs and an organic silicone resin binder, shows both excellent hot water repellency and mechanical robustness, which, together, promise potential applications in hot liquid self-cleaning and high efficiency heat transfer. This journal is © The Royal Society of Chemistry 2015. Source

Li W.,Wuxi Shunye Technology Co. | Yang J.,Wuxi Shunye Technology Co. | Yang J.,McGill University | Yang J.,Rosalind and Morris Goodman Cancer Research Center | And 3 more authors.
Materials Research Express | Year: 2015

We report a simple route for the synthesis of several morphologies of self-assembling hierarchical Ni (OH)2 nanostructures, by the reaction of NiSO4 and NH4OH in aqueous solution, at a constant temperature, using neither surfactant nor template. Both morphology and microstructure depend on the concentrations of the reactants, the reaction temperature and the anions (Cl-, .., NO3 - and SO4 2-) present. The nanostructures have been characterized by scanning electron microscopy (SEM) and x-ray diffraction (XRD). When SO4 2-is used, irrespective of the presence of other anions, only microspheres of hierarchical Ni(OH)2 nanosheets are present, suggesting that this anion plays a critical role in microsphere formation. Electrochemical characterizations of Ni(OH)2 nanosheets show good supercapacitor performance, with relatively high capacity and excellent rate capability, indicating that these hierarchical Ni(OH)2 nanosheets are serious candidates for energy storage applications. The growth mechanism for nanosheet formation is discussed, based on SEM observations under different preparation conditions, detailing the transition from nanoparticles to nanowires to nanosheets. The specific surface area and the thickness of our Ni(OH)2 nanosheets have been determined to be 149.6 m2 g-1 and 20-30 nm, respectively. © 2015 IOP Publishing Ltd. Source

Yu Z.-J.,Wuxi Shunye Technology Co. | Yang J.,McGill University | Wan F.,Wuxi Shunye Technology Co. | Ge Q.,Wuxi Shunye Technology Co. | And 5 more authors.
Journal of Materials Chemistry A | Year: 2014

Superhydrophobic surfaces, with water contact angles greater than 150° and slide angles less than 10°, have attracted a great deal of attention due to their self-cleaning ability and excellent water-repellency. It is commonly accepted that a superhydrophobic surface loses its superhydrophobicity in contact with water hotter than 50 °C. Such a phenomenon was recently demonstrated by Liu et al. [J. Mater. Chem., 2009, 19, 5602], using both natural lotus leaf and artificial leaf-like surfaces. However, our work has shown that superhydrophobic surfaces maintained their superhydrophobicity, even in water at 80 °C, provided that the leaf temperature is greater than that of the water droplet. In this paper, we report on the wettability of water droplets on superhydrophobic thin films, as a function of both their temperatures. The results have shown that both the water contact and slide angles on the surfaces will remain unchanged when the temperature of the water droplet is greater than that of the surface. The water contact angle, or the slide angle, will decrease or increase, however, with droplet temperatures increasingly greater than that of the surfaces. We propose that, in such cases, the loss of superhydrophobicity of the surfaces is caused by evaporation of the hot water molecules and their condensation on the cooler surface. © 2014 the Partner Organisations. Source

Wang L.,Kunming University of Science and Technology | Wang L.,Wuxi Shunye Technology Co. | Yang J.,Wuxi Shunye Technology Co. | Yang J.,McGill University | And 7 more authors.
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2016

Both mechanical and chemical durability of superhydrophobic (SH) surfaces are very important properties for industrial applications. In this paper, the durability of the Ultra-Ever Dry, as a commercial SH product, sprayed onto low carbon steel has been systematically studied by sand paper abrasion, waterfall/jet test and immersion in solution of different pH values as well as salt spray test. The results show that the degeneration of superhydrophobicity of the coating during the abrasion was mainly due to the loss of both the top layer of micro-scale bumps and their nanoparticles (NPs). Waterfall/jet impact could also cause the loss of NPs on the micro-scale bumps of the coating, which corresponds with the change of wettability. Different chemical processes elicit complex effects on the SH Surface. The coating is able to maintain its superhydrophobicity in solutions of pH 1-12, whereas a solution of pH 14 causes both chemical change and loss of NPs, and as a result, the loss of the water-repellent property. The salt spray test shows that the pitting corrosion on the surface and the degeneration of superhydrophobicity are mainly induced by morphological and surface chemical changes such as the formation of new Fe-O nanostructures that presented as pit-etching on the coating surface. The results also confirm that surperhydrophobictity degeneration of the SH coating surface by salt spray can be easily recovered through treatment with fluoroalkylsilane (FAS-17). © 2016 Elsevier B.V. Source

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