Showing papers by "Yunchen Du published in 2014"

Shell thickness-dependent microwave absorption of core-shell Fe3O4@C composites.

Abstract: Core–shell composites, Fe3O4@C, with 500 nm Fe3O4 microspheres as cores have been successfully prepared through in situ polymerization of phenolic resin on the Fe3O4 surface and subsequent high-temperature carbonization. The thickness of carbon shell, from 20 to 70 nm, can be well controlled by modulating the weight ratio of resorcinol and Fe3O4 microspheres. Carbothermic reduction has not been triggered at present conditions, thus the crystalline phase and magnetic property of Fe3O4 micropsheres can be well preserved during the carbonization process. Although carbon shells display amorphous nature, Raman spectra reveal that the presence of Fe3O4 micropsheres can promote their graphitization degree to a certain extent. Coating Fe3O4 microspheres with carbon shells will not only increase the complex permittivity but also improve characteristic impedance, leading to multiple relaxation processes in these composites, thus the microwave absorption properties of these composites are greatly enhanced. Very inte...

Multifunctional polymer–metal nanocomposites via direct chemical reduction by conjugated polymers

Abstract: Noble metal nanoparticles (MNPs) have attracted continuous attention due to their promising applications in chemistry, physics, bioscience, medicine and materials science. As an alternative to conventional solution chemistry routes, MNPs can be directly synthesized through a conjugated polymer (CP) mediated technique utilizing the redox chemistry of CPs to chemically reduce the metal ions and modulate the size, morphology, and structure of the MNPs. The as-prepared multifunctional CP–MNP nanocomposites have shown application potentials as highly sensitive surface enhanced Raman spectroscopy (SERS) substrates, effective heterogeneous catalysts for organic synthesis and electrochemistry, and key components for electronic and sensing devices. In this tutorial review, we begin with a brief introduction to the chemical nature and redox properties of CPs that enable the spontaneous reduction of noble metal ions to form MNPs. We then focus on recent progress in control over the size, morphology and structure of MNPs during the conjugated polymer mediated syntheses of CP–MNP nanocomposites. Finally, we highlight the multifunctional CP–MNP nanocomposites toward their applications in sensing, catalysis, and electronic devices.

γ-irradiation induced one-step synthesis of electromagnetic functionalized reduced graphene oxide–Ni nanocomposites

Abstract: We here demonstrate a facile one-step synthesis of RGO–Ni hybrid materials, where Ni2+ ions and GO are simultaneously reduced by γ-irradiation. RGO–Ni, with Ni nanoparticles well dispersed on the RGO surface, shows a more enhanced EM absorption ability than the individuals.

Multifunctional Polymer—Metal Nanocomposites via Direct Chemical Reduction by Conjugated Polymers

Abstract: Review: syntheses and application of multifunctional conjugated polymer — nobel metal nanocomposites in sensing, catalysis, and electronic devices; 50 refs.

Superhydrophobic Ag nanostructures on polyaniline membranes with strong SERS enhancement

Abstract: We demonstrate here a facile fabrication of n-dodecyl mercaptan-modified superhydrophobic Ag nanostructures on polyaniline membranes for molecular detection based on SERS technique, which combines the superhydrophobic condensation effect and the high enhancement factor. It is calculated that the as-fabricated superhydrophobic substrate can exhibit a 21-fold stronger molecular condensation, and thus further amplifies the SERS signal to achieve more sensitive detection. The detection limit of the target molecule, methylene blue (MB), on this superhydrophobic substrate can be 1 order of magnitude higher than that on the hydrophilic substrate. With high reproducibility, the feasibility of using this SERS-active superhydrophobic substrate for quantitative molecular detection is explored. A partial least squares (PLS) model was established for the quantification of MB by SERS, with correlation coefficient R2 = 95.1% and root-mean-squared error of prediction (RMSEP) = 0.226. We believe this superhydrophobic SERS substrate can be widely used in trace analysis due to its facile fabrication, high signal reproducibility and promising SERS performance.

Chemical deposition of Ag nanostructures on polypyrrole films as active SERS substrates

Abstract: A facile synthesis of homogeneous Ag nanostructures on modified polypyrrole (PPy) films through direct chemical deposition has been demonstrated. The as-prepared Ag nanostructures are highly sensitive and reproducible in the SERS detection of the target analyte, methylene blue (MB).