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Linear- and parallel-aligned gold nanorods (GNRs) were self-assembled on glass substrates and their surface-enhanced Raman scattering effect was investigated. GNRs were prepared by seed-mediated growth method and self-assembled to form linear and parallel aggregation on the substrate. The parallel-aligned GNRs showed weak optical absorption intensities in the visible to infrared wavelength region. On the other hand, the linear-aligned GNRs exhibited strong optical absorption bands peaking at 830 and 2200nm, which are assigned to the weakly coupled surface plasmons of the GNRs. When Rhodamine-6G molecules were adsorbed on the linear-aligned GNRs, strong surface-enhanced Raman scattering spectra were observed.

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Single-crystalline platinum nanocubes with porous morphology were synthesized for the first time by using ethylene glycol, HCl, and polyvinylpyrrolidone as the reducing agents of H2PtCl6. The morphology and size distribution of the Pt particles formed were studied with a high-resolution transmission electron microscope and selected-area electron diffraction pattern. By controlling the material concentrations and reaction temperature and period, Pt single crystals about 5 nm in size were formed in the first stage of the reduction process that had {100} facets, which were stacked one on top of the other, forming porous nanocubes 20-80 nm in length. The synthesized Pt nanocubes exhibited enhanced catalytic activity for methanol oxidation.

The use of plasmonic nanoparticles (NPs) in dye-sensitized solar cells (DSSCs) in an effort to enhance their power conversion efficiencies (PCEs) increases light absorbance of the cells but also affect their electron dynamics. This has contributed to the failure of plasmonic NPs to make the expected high impact of PCE enhancement. Herein, we investigated the wide range effects of plasmonic NPs on the performance of DSSCs, using extended characterization and a systematic approach. We prepared DSSCs using Ag@TiO2 NPs-doped TiO2 photoanodes. Using a wide range doping concentration, we obtained panchromatic enhancement effect with two optimal doping concentrations (0.1 and 1 wt. %).They enhanced PCE via mainly: a) optimal band alignment for efficient charge injection; and b) a balance of the negative and positive effects of plasmonic NPs on cell performance parameters (open circuit voltage, fill factor, charge transfer resistance against recombination, electron life time and charge collection efficiency); respectively. The PCE of the pristine sample increased from 4.66 to 4.88 and 5.00% via these 2 routes, respectively. The major cause of not obtaining very high PCE was charge recombination from high charge density. Thus, these observations might serve as invaluable guidance for the preparation of highly efficient plasmonic DSSCs.

We report studies on the end-to-end assembly of CTAB-stabilized gold nanorods (GNRs) dispersing in an aqueous solution. The addition of sodium citrate to the solution of GNRs with an aspect ratio (AR) of 3 causes the end-to-end assembly accompanied with a red-shift of longitudinal surface plasmon resonance (LSPR) band of the GNRs in the optical extinction spectrum. The red-shift in the LSPR band continues until the solution becomes colorless and transparent, whereas adding CTAB brings the color change to a stop, resulting in the long term-stable LSPR of the end-to-end connected GNRs. Added citrate anions are found to be adsorbed on only the end faces of GNRs so that they are considered to neutralize the surface charge of the GNR ends, resulting in the end-to-end assembly of the GNRs. On the other hand, GNRs with an AR of 16 are end-to-end assembled by decreasing CTAB concentration in the solution. The assembled GNRs are welded at their connecting points by the further decrease of CTAB concentration in the solution. Such end-to-end aggregated GNRs presumably have an advantage of electron conduction, whereas the end-to-end connected GNRs with a slight space between two GNRs could be ideal substrate for surface enhanced Raman spectroscopy.