Chemically modified electrode spectroscopy

Impedance spectroscopy is an effective technique for probing the features of chemically-modified electrodes and for understanding electrochemical reaction rates (87,88). Impedance is the totally complex resistance encountered... 

Summary, Scanning probe microscopy studies of electrodes chemically modified with electroactive transition metal complexes are described. Emphasis is placed on scanning tunneling microscopy and electrochemical scanning tunneling microscopy studies of their structure and dynamics of formation and on electrochemical force spectroscopy studies of their electrochemical potential dependent chemical properties. 

These coated glasses can be used as working electrodes [optically transparent electrodes (OTE)] in standard three-electrode arrangements provided that both glass and coating are chemically and electrochemically stable and inert in the used electrolyte solution and the applied range of electrode potentials. The use of a modified infrared spectroscopy transmission cell equipped with quartz windows for UV-Vis spectroelectrochemistry has been described [18]. Platinum layers deposited onto the quartz served as an optically transparent working electrode and an additional platinum layer served as a pseudo-reference electrode. A counter electrode outside the thin layer zone (in one of the tubes used for solution supply) served as a counter... 

Canah, C., Larsen, L. B., Martinsen, 0. G., Heiskanen, A. (2015). Conductometric analysis in bio-applications a mriversal impedance spectroscopy-based approach using modified electrodes. Sensors Actuators B. Chemical, 212, 544-550. 

Microelectronic technologies have also been used in nitrite biosensors and electrochemical sensors (Suzuki and Taura, 2001 Adhikari and Majumdar, 2004). Ameida et al. (2013) have also developed a method of electrochemical nitrite measurement by means of a gold working electrode covered with 1,2-diaminobenzene (DAB) integrated in a FIA system. This sensor helps improve selectivity, repeatability, stability, and sensitivity. A Nafion/lead-ruthenate pyrochlore electrode chemically modified for determination of NO2 oxidation and NO reduction based on AC-impedance spectroscopy and FIA has also been tested (Zen et al., 2000). Quan and Shin (2010) also tested an electrochemical nitrite biosensor based on co-immobilization of copper-containing nitrite reductase and viologen-modified chitosan (CHIT-V) on a glassy carbon electrode (GCE). 

The ESTM experiment provides actually five measurable quantities tunnelling current, / at the applied voltage, U, and three dimensions, x, y, z. The standard STM can therefore easily be modified by recording the local l-Uy U-zy or /-z characteristics (z is vertical distance of the tip from the electrode surface). Plot of dl/dU or d//dz versus x and y brings additional information on the electronic and chemical surface properties (local work functions, density-of-states effects, etc.), since these manifest themselves primarily as l-U dependences. The mentioned plots are basis of the scanning tunnelling spectroscopy (STS). 

Another advantage of the SERS spectroscopy is to obtain vibrational spectroscopic informations in electrolyte solution under conditions close to the real biological situation. The continuous development of laser sources with new excitation wavelength lines renders it possible to expand the study of adsorbed biomolecules on different metal surfaces which can also be chemically or electrically modified to adjust specific adsorption properties. Such a crucial event in medical applications as the behaviour of implants in contact with blood can be thus envisaged by the study of the adsorption of blood proteins and its physiological consequences. The possibility to monitor the interfacial electric field of the electrode surface can also be used to... 

ABSTRACT The acquisition and analysis of electrochemical impedance spectroscopy (EIS) and electrochemical quartz crystal microbalance (EQCM) data in one cychc potential scan allows a detailed characterization of complex non-stationary eleetrode/eleetrolyte interfaces. Analysis of the EIS-EQCM data-set enables efficient elucidation of physical models of studied systems and determination of their physico-chemical parameters. The underpotential deposition of Pb atomic layers on gold electrodes modified with an atomic layer of Ag has been used as a model system to demonstrate the EIS-EQCM approach. 

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