The shape control of Au nanocrystals is crucial to their catalytic applications and optical properties. Well-defined Au nanodendrites (NDs) have been prepared on a glassy carbon electrode using low-potential synthesis, assisted by ethylenediamine (EDA). The effects of applied potential, deposition time, and HAuCl(4) (or EDA) concentrations on the morphology of the Au deposits are discussed in our work. The growth mechanism can be explained by a two-staged growth of dendrites: initial branching and subsequent dendritic growth. The Au NDs exhibits superior catalytic performance toward ethanol oxidation, in comparison with the polycrystalline Au nanoparticles. The simple and facile synthetic technique can be applied to the construction of other metals with complex hierarchical structures on a large-scale.

Hollow ZnO superstructures have potential technological applications. With this motivation, a simple approach is developed to prepare hollow double-caged peanut-like ZnO hierarchical superstructures with the assistance of apple pectin. The biotemplate-assisted approach concurs with ''green'' chemistry as it is simple and environmentally friendly. The products are characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results reveal that the pectin-directed hydrothermal process is essential to obtain the final products. The morphologies and dimensions of the ZnO structures could be easily tuned by varying the molar ratios of the pectin to zinc ion, the amount of ammonia, the reaction time and the temperature. A possible formation mechanism for the hollow superstructures is described. In addition, the optical properties of the ZnO superstructures were investigated in some detail. The as-prepared samples showed high photocatalytic activity towards methyl orange (MO) under ultraviolet (UV) irradiation.

No abstract

No abstract

Carbon dots (CDs) as versatile carbon-based nanomaterials have attracted increasing attention because of their non-toxicity, good water solubility and photostability, and easy surface functionalization. For their wide application, it is still needed to explore moderate and facile methods for synthesizing CDs from green and inexpensive precursors. In this paper, a moderate method was developed to synthesize water-soluble CDs by ionothermal treatment of cellulose with SO 3 H-functionalized acidic ionic liquid as a catalyst in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). The preparation process was carried out at relatively low temperature in non-pressurized vessel. The synthesized CDs exhibit near-spherical morphology with an average diameter of 8.0 nm, and the surface is carbon and oxygen rich. The CDs have powder-blue fluorescence with excitation-dependent emission behavior and excellent stability. Moreover, the as-prepared CDs were demonstrated as an effective ''turn-off'' fluorescent probe for the selective detection of Hg 2? with a good linear relationship over the concentration range from 6 to 80 lM. The application of acidic ionic liquid should provide a new path for the synthesis of CDs under mild condition.

No abstract

Au NCs with different morphologies were synthesized in DESs by changing water contents, and used as electrocatalysts for ethanol electrooxidation.

In this study, we synthesized a series of pH-sensitive and salt-sensitive N-succinyl-chitosan hydrogels with N-succinyl-chitosan (NSCS) and the crosslinker glycidoxypropyltrimethoxysilane (GPTMS) via a one-step hydrothermal process. The structure and morphology analysis of the NSCS and glycidoxypropyltrimethoxysilane-N-succinyl chitosan hydrogel (GNCH) revealed the close relation between the swelling behavior of hydrogels and the content of crosslinker GPTMS. The high GPTMS content could weaken the swelling capacity of hydrogels and improve their mechanical properties. The hydrogels show high pH sensitivity and reversibility in the range of pH 1.0 to 9.0, and exhibit on-off switching behavior between acidic and alkaline environments. In addition, the hydrogels perform smart swelling behaviors in NaCl, CaCl2, and FeCl3 solutions. These hydrogels may have great potential in medical applications.