An integrated electrochromic nanoplasmonic optical switch.

We demonstrate an electrochemically driven optical switch based on absorption modulation of surface plasmon polaritons (SPPs) propagating in a metallic nanoslit waveguide containing nanocrystals of electrochromic Prussian Blue dye. Optical transmission modulation of ∼96% is achieved by electrochemically switching the dye between its oxidized and reduced states using voltages below 1 V. High spatial overlap and long interaction length between the SPP and the active material are achieved by preferential growth of PB nanocrystals on the nanoslit sidewalls. The resulting orthogonalization between the directions of light propagation and that of charge transport from the electrolyte to ultrathin active material inside the nanoslit waveguide offers significant promise for the realization of electrochromic devices with record switching speeds.

Capping polymer-enhanced electrocatalytic activity on Pt nanoparticles: a combined electrochemical and in situ IR spectroelectrochemical study.

Unexpected yet highly remarkable and intriguing observations of the polymer-enhanced electro-catalytic activity of the Pt nanoparticles for electro-oxidations of both methanol and formic acid were reported. In situ FTIR investigation suggests strongly that the observed activity enhancements are highly likely due to the PVP-induced additional reaction pathways. These observations may open up a new paradigm of research in which the protecting/stabilizing organic ligands can now be incorporated as an advantageous part and/or a finer catalytic activity tuner of a nanocatalytic system.

An unexpected enhancement in methanol electro-oxidation on an ensemble of Pt(111) nanofacets: a case of nanoscale single crystal ensemble electrocatalysis.

Pt nanoparticles having the same size ( approximately 10 nm) but different shapes (cubic or octahedral/tetrahedral), as determined by transmission electron microscopy, were synthesized via a polyol-based synthetic procedure. Their respective electrocatalytic activities for methanol oxidation were characterized by cyclic voltammetry and chronoamperometry in both sulfuric and perchloric acid electrolytes, which showed clear shape (surface orientation) dependences. Furthermore, the octahedral/tetrahedral Pt nanoparticles displayed an unexpectedly large enhancement in methanol electro-oxidation activity; about 3-fold increase in transient intrinsic activity and 10-fold increase in CO tolerance steady-state activity when compared to commercial Pt black. Gaseous and methanolic CO adsorption on the synthesized nanoparticles were also investigated by surface-enhanced IR absorption spectroscopy in perchloric acid electrolyte, which suggested that the different trends observed might be related to the electronic effects specific to a given ensemble of the nanofacets.

Plasma enhanced chemical vapor depositions to encapsulate crystals in thin polymeric films: a new approach to controlling drug release rates.

An RF plasma discharge was employed to deposit thin polymeric films on drug particles. This study utilized acetylsalicylic acid (aspirin) crystals and allyl alcohol as polymerizable monomer for this new approach to controlling drug release rates. Release rates of coated and uncoated particles were measured in aqueous solution at a pH of 1.0. The drug release rates could be varied over wide ranges by appropriate control of the polymeric films. These controls included film composition, extent of polymer cross-linking and film thickness. A 360 degrees rotating plasma reactor was employed to provide effective agitation and mixing of the drug particles during the coating operation. The plasma discharge was operated in a pulsed mode to provide improved control of the polymer film compositions and, at the same time, minimize undesirable decomposition of drug molecules. Overall, the results obtained clearly indicate that the pulsed RF plasma coating process developed represents a viable, one-step, solventless route to controlled drug release.