Gold electrodes capacitance

Mortari, A., Maaroof A., Martin, D. and Cortie, M.B. (2007) Mesoporous gold electrodes for measurement of electrolytic double layer capacitance. Sensors and Actuators B, 123, 262-268. 

M. Vladimir, M. Mirsky, O. Riepl, and O. Wolfbeis, Capacitive monitoring of protein immobilization and antigen—antibody reactions on monomolecular alkylthiol films on gold electrodes. Biosens. Bioelectron. 12, 977-989 (1997). 

Adsorption of cyanide anions can be affected by adsorption of cations. In the solutions containing nonspecifically adsorbed anions, the nature of alkali metal cations was found to influence the measured value of the electrode capacitance at potentials more negative than —0.6 V (versus standard hydrogen electrode (SHE)). At < —l.OV adsorption of CN ions was enhanced in the presence of Li+ and Na+ cations, and inhibited in the presence of Cs+ ions [81]. A combined SERS and density-functional theory has been applied to study cyanide adsorption at Au electrode [82]. The authors have arrived at the conclusion that the polarity of Au—CN bonds falls between that of Au—Cl and Au—Br surface bonds. The binding strength for three different gold surfaces decreased in the order ... 

Adsorption of putidaredoxin on gold electrodes has been studied using dynamic spectroscopic ellipsometry and differential capacitance measurements [307]. In Ref. 307, a method for the measurement of metal surface optical perturbation during protein adsorption at a constant potential has been described. The method is based on the concept that the charged transition layer develops between the electrode substrate and the adsorbate. 

Herbicides, like demestryn, have been determined using a chemosensor based on the MIP film recognition and capacitive transduction [193, 194]. In this determination, photografting polymerization has been demonstrated as an efficient procedure for fabrication of a capacitive chemosensor. This procedure involved immobilization of an initiator on the electrode. In this case, first, an alkanethiol monolayer was self-assembled on the gold electrode. This monolayer was perfectly dielectric. Then, an MIP film was deposited on top of this monolayer by photo-radical polymerization in the acetone solution with benzophenone, 2-acrylamido-2-methyl-1-propane sulphonic acid, /V./V -iriethylenediacrylamide and demestryn used as the initiator, cross-linker, functional monomer and template, respectively. Subsequently, the template was extracted with methanol. The capacitance decreased by 20% upon binding the demestryn analyte by the MIP film. Similarly, a creatine chemosensor was constructed [194],... 

A gold electrode with self-assembled monolayers, in the absence of any redox species, is an almost ideally polarized (i.e., purely capacitive) interface. A Nyquist... 

SPR detection of hybridization and denaturation kinetics for tethered ssDNA thiol on gold was achieved by monitoring the gain or loss of DNA at the interface in the presence of an applied electrostatic field. Redox reactions were avoided and the current measured was limited to the capacitive, non-faradaic charging current, at selected potentials applied to the gold electrode interface, as described by Georgiadis and co-workers [47], The specific DNA thiol monolayer films were robust and could be reused. 

A capacitive sensor with a molecularly imprinted polymer film as a sensitive layer has been reported. The layer was prepared by electropolymerization of phenol on a gold electrode with the template molecule, phenylalanine. The sensor capacitance was decreased by the addition of phenylalanine, but there was almost no change with glycine, tryptophan and phenol. The response time was 15 min (time for a half of the stationary value, 60 min), and the dynamic range was given as 0.5 to... 

Figure 14.5.5 CV charging currents at 0.1 V/s for a bare polycrystalline gold electrode (A 1 cm ) in 1 M Na2S04 [solid line (left current scale)] and coated with a Cig alkyl thiol [coarse dashed line (right current scale) and fine dashed line (left current scale)]. The decrease in capacitance upon coating is by about a factor of 80. [Reprinted from H. O. Finklea, Electroanal Chem., 19, 109 (1996), by courtesy of Marcel Dekker, Inc.]...

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