We present a facile approach for the fabrication of a nanocomposite comprising α-Fe(2)O(3) nanotubes (NTs) anchored on reduced graphene oxide (rGO) for electrochemical capacitors (ECs). The hollow tubular structure of the α-Fe(2)O(3) NTs presents a high surface area for reaction, while the incorporation of rGO provides an efficient two-dimensional conductive pathway to allow fast, reversible redox reaction. As a result, the nanocomposite materials exhibit a specific capacitance which is remarkably higher (~7 times) than α-Fe(2)O(3) NTs alone. In addition, the nanocomposites show excellent cycling life and large negative potential window. These findings suggest that such nanocomposites are a promising candidate as negative electrodes in asymmetrical capacitors with neutral electrolytes.

Hybrid composites of CdS nanoparticles embedded in sulfonated polystyrene (PS) matrixes have been prepared and characterized. The -SO 3groups acted as the coordination sites for cadmium ion aggregations and nanosized CdS particles were successfully grown in situ at these sites with the release of S 2ions from thioacetamide. The density and size of the nanoparticles were found to be a function of the sulfonate content of PS and the concentration of Cd 2+ feed ions used. Ionic clusterings within the polymer matrix occurred at a sulfonate content of 9.9 mol % and has provided a confined medium for particle growth in uniform size. The optical properties of the prepared CdS-PS hybrid composites were characterized by linear absorption and fluorescence spectra. Z-scan measurement was also employed to investigate the nonlinear optical properties at a wavelength of 532 nm. The results showed that the nonlinear refractive index of the composite varies with the input irradiance, thus indicating not just third-order but possible higher order nonlinearity.

In control! Ag2S nanocrystals of predictable size and shape were synthesized from the precursor Ag(SCOPh) in the presence of an amine. Careful tuning of several parameters, such as the reaction temperature and the ratio of amine to precursor, led to Ag2S nanocrystals of varying morphology (red: nanocubes; blue: faceted nanocrystals; yellow: nanorods) and size. x=particle size. HDA=hexadecylamine.

Three-dimensional self-assembled monolayer (3D SAM) of 1-octanethiol, 1-decanethiol, and 1-dodecanethiol has been formed on copper nanoclusters. The morphology and spectroscopy of the nanoparticles were characterized while the conformation of the 3D SAMs was investigated with thermal and variable-temperature analyses. TEM results suggest the copper clusters consist of a spherical shape of ∼3−5 nm. IR, XPS, and 13C CPMAS NMR results confirm that alkanethiols are chemisorbed via the −SH group and the packing density of the alkanethiols on copper nanoclusters increases with the alkyl chain lengths. The thiol chain is deduced to adopt the all-trans zigzag conformation through the analysis by IR and 13C CPMAS NMR. Low-angle peaks observed in XRD further suggest strong interdigitation among these chains to form superlattice structures. On increasing temperature, VT-FTIR and VT-13C CPMAS NMR depict the disruption of lateral interaction between the chains. This melting of crystalline packing is endothermic but an exothermic peak was observed upon reheating in DSC. We attribute this exothermic “crystallization” to the conformational memory effect of the compact chains. We have found that much higher melting points and enthalpies are obtained on copper nanoclusters as compared to earlier reports on gold and silver clusters.

Monodispersed copper sulfide nanocrystals were synthesized via the decomposition of an air-stable precursor, copper (I) thiobenzoate (CuTB), in the presence of dodecanethiol (DDT). We discover that, by varying the stabilizing agent used (trioctylphosphine or tributylphosphite), we can selectively generate phase-pure roxbyite nanoplates (Cu 1.75 S) or chalcocite faceted nanocrystals (Cu 2 S). We also demonstrate that, under suitable conditions, the roxbyite nanoplates can be forced to grow only in two dimensions, with an aspect ratio (diameter/thickness) tunable between 2.3 and 4.1. To the best of our knowledge, this is the first report for making nanocrystalline copper sulfide with such aspect ratio tunability. Temperature and the [DDT]/[CuTB] ratio were identified to be the important factors for controlling the size of the nanocrystals. To gain more insight to the mechanisms of phase-selective control, we attempted a series of controlled experiments and DFT calculations. It appears that the precursor can undergo two competitive pathways, leading to seeds, and thus the growth, of different crystal phases. This work thus demonstrates a general approach to phase-selective nanocrystals engineering whereby the kinetics of decomposition of a chosen precursor is readily manipulated using activating or stabilizing agents.