23 research outputs found
Electrochemical Impedance Spectroscopy in Interfacial Studies
An important role of the electrochemical impedance spectroscopy (EIS) is the characterization of the electrical double layer formed at the electrode/electrolyte interfaces. The phenomenological double layer studies with an aqueous and ionic liquid electrolytes are reviewed with a conclusion that the double layer capacitance is frequency dependent as the rule rather than the exception. We discuss the impedance consequences of the nonuniform current distribution along the electrochemical interface, which also contributes to the apparent frequency dependence of the capacitance. Finally we show recent articles on nonconventional EIS techniques with high lateral resolution or enabling fast measurements
A Comparative Plasmonic Study of Nanoporous and Evaporated Gold Films
Previously, we have reported that nanoporous gold (NPG) films prepared by a chemical dealloying method have distinctive plasmonic properties, i.e., they can simultaneously support localized and propagating surface plasmon resonance modes (l-SPR and p-SPR, respectively). In this study, the plasmonic properties of NPG are quantified through direct comparison with thermally evaporated gold (EG) films. Cyclic voltammetry and electrochemical impedance spectroscopy experiments reveal that the NPG films have 4â8.5 times more accessible surface area than EG films. Assemblies of streptavidinâlatex beads generate p-SPR responses on both NPG and EG films that correlate well with the bead density obtained from scanning electron microscopy (SEM) images. A layer-by-layer assembly experiment on NPG involving biotinylated anti-avidin IgG and avidin, studied by l-SPR and SEM, shows that the l-SPR signal is directly linked to the accessibility of the interior of the NPG porosity, an adjustable experimental parameter that can be set by the dealloying condition and time
The Effect of pH on the Electrical Capacitance of PhosphatidylcholineâPhosphatidylserine System in Bilayer Lipid Membrane
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Tailoring the morphology of WOâfilms with substitutional cation doping: Effect on the photoelectrochemical properties
With the aim of improving the performance and extending the range of applications of mesoporous WOâfilms, which were initially developed for the photoelectrochemical oxidation of water, we investigated the effect of a number of dopants (lithium, silicon, ruthenium, molybdenum and tin) upon the transparency, crystallinity, porosity and conductivity of the modified films. Tin, molybdenum and silicon were shown to improve the electrochromic behaviour of the layers whereas ruthenium enhanced considerably the electronic conductivity of the WOâfilms. Interestingly, most of the dopants also affected the film morphology and the size of WOânanocrystals. X-ray photoelectron spectra revealed absence of significant segregation of doping elements within the film. Raman analyses confirmed that the monoclinic structure of WOâfilms does not change upon substitutional cation doping; thus, the crystallinity of WOâfilms is maintained