Indium oxide optically transparent electrode

Delta Technologies 13960 N. 47th St. Stillwater, MN 55802-1234 Indium oxide optically transparent electrodes on glass and quartz... 

Bowden, E. F., Hawkridge, F. M., Chlebowski, J. F., Bancroft, E. E., Thorpe, C., Blount, H. N., Cyclic Voltammetry and Derivative Cyclic Voltabsorptometry of Purified Horse Heart Cytochrome C at Tin-Doped Indium Oxide Optically Transparent Electrodes , J. Am. Chem. Soc. 104 (1982) 7641-7644. 

Figure 18. (A) Cyclic voltammetry of purified cytochrome c at doped indium oxide optically transparent electrodes. Solution contained 73 /uiM cytochrome c, 0.21 M Tris, 0.24 M cacodylic acid, pH 7.0, 0.20 M ionic strength. Electrode area = 0.71 cm. Potential scan rates in mV/s are (a) 100 (b) 50 (c) 20 (d) 10 (e) 5.0 (f) 2.0. (B) Derivative cyclic voltabsorptometry of purified cytochrome c at a tin-doped indium oxide optically transparent electrode. Same conditions as described above. Circles are calculated derivative cyclic voltabsorptometric responses for 73 /iM cytochrome c, formal potential = 0.260 V, n = 1.0, diffusion coefficient of oxidized and reduced cytochrome c = 1.2 x 10 cm /s, difference molar absorptivity at 416 nm = 57,000 cm" formal heterogeneous electron transfer rate constant = 1.0 x 10 cm/s, and electrochemical transfer coefficient = 0.5. Adapted from Reference (126) with permission.

Bowden EF, Hawkridge FM, Chlebowski JF, Bancroft EE, Thorpe C, Blount HN. Cyclic voltammehy and derivative cyclic voltabsorptomehy of purified horse heart cytochrome-C at tin-doped indium oxide optically transparent electrodes. J Am Chem Soc 1982 104 7641-7644. 

The heterogeneous electron transfer kinetics of cytochrome c at tin-doped indium oxide and fluoride-doped tin oxide optically transparent electrodes... 

Figure 33.1a illustrates the idea of the smart window. In this device a layer of electrochromic material and a layer of a transparent ion-conducting electrolyte are sandwiched between two optically transparent electrodes (OTEs). Indium-doped tin oxide on glass is used most commonly as the OTE. This material has very low... 

To learn how to lest if an optically transparent electrode made of indium-tin oxide (ITO) is dirty or over-reduced, and therefore unsuitable for electroanalyses, Just by visual examination. 

Indium-tin oxide (ITO) Tin-doped indium oxide, used as a thin solid film on glass when constructing optically transparent electrodes. 

Fig. 9. 22 Absorption spectrum of ZnO colloids (diameter 29.3 A) in ethanol at different electrode potentials (reference electrode Ag/AgCl). The light was transmitted through an optically transparent electrode (indium tin oxide (ITO) layer on glass). Insert difference spectra between -0.6 and -0.95 V and -0.6 and -1.1 V. (After ref. [64])...

The first studies by UV-visible transmission spectroscopy were carried out using an optically transparent electrode (OTE) such as indium oxide [140,141]. Unfortunately an OTE does not allow the nature and the structure of the electrode material to be changed and these play a key role in electrocatalytic processes. Only reflectance spectroscopy is able to investigate in situ, various electrode materials [142], This was effectively checked for the first time with cobalt porphyrin-doped polypyrrole films using the electroreflectance technique [106,143]. This allowed the characterization of the redox properties of the modified PPy electrode and the determination of the redox potential of the Co"VCo" couple. The catalytic effect towards the ORR was also... 

For combined studies involving spectroscopic methods, in particular, the possibility of using optically transparent electrodes made from glass coated with indium-tin-oxide (ITO) or similar materials, e.g., Sn02/F or Sn02/Sb, should be taken into account (see Chap. Chapter n.6). However, because of their chemical nature, studies of reduction reactions are naturally limited with such electrodes. 

In many spectroelectrochemical studies, optically transparent electrodes, which are transparent to radiation in a particular spectral region, have been widely used. One type of transparent electrode consists of a very thin film of conductive material such as platinum, gold, tin oxide, indium oxide, or carbon, which is deposited on a transparent substrate such as glass (visible), quartz (UV-visible), or germanium (IR). A second type of transparent electrode is the minigrid electrode. 

With optically transparent electrodes (OTE), molecular adsorbates, polymer films, or other modifying layers attached to the electrode surface or being present in the phase adjacent to the electrode can be studied. With opaque electrode materials, internal or external reflection may be applied. Glass, quartz, or plastic substrates coated with a thin layer of semiconductors (indium-doped tin oxide) or conducting metals (gold, platinum) are often used as OTE. The optically transparent electrode is immersed as working electrode in a standard cuvette. 

The polymers are generally deposited on inert substrates such as platinum, gold or glassy carbon electrodes and on indium-tin-oxide (ITO) transparent electrodes for electron spectroscopy. In the latter case differences were observed in the optical spectra of poly(3-methylthiophene) films electrodeposited on electrodes of different surface resistivities [46]. However, electrodepositions have been also performed on other surfaces such as titanium [49] or iron [50]. 

A final class of materials is the optically transparent electrodes based on metal oxides (e.g., indium-tin oxide, ITO). These materials are very popular in the field of energy conversion, as a support for Dye-Sensitive Solar Cells, but the group of Heinemann developed at the end of the 1990s a spectroelectrochemical sensing method based on such transparent electrodes. The method is defined as the coupling of an electrochemical detection with a spectroscopic analysis." " This approach allows for multimode selectivity and is usually applied in the presence of surface modification for preconcentration of the analyte. More recently, porous and optically transparent electrodes have been prepared and applied for combined spectroscopic and electrochemical analysis" " which should lead in a near future to further developments in analytical sciences applied to the environment. 

The changes in the optical absorption spectra of conducting polymers can be monitored using optoelectrochemical techniques. The optical spectmm of a thin polymer film, mounted on a transparent electrode, such as indium tin oxide (ITO) coated glass, is recorded. The cell is fitted with a counter and reference electrode so that the potential at the polymer-coated electrode can be controlled electrochemically. The absorption spectmm is recorded as a function of electrode potential, and the evolution of the polymer s band stmcture can be observed as it changes from insulating to conducting (11). 

In situ UV-visible spectroscopy monitors the energy of electrons within the analyte. While, strictly speaking, all materials change their UV-visible spectrum in accompaniment with electrode reactions (they are said to be electrochromic), the majority of these changes are not discernible by the human eye, and therefore may not be useful to the analyst. Electrodes must be optically transparent for in situ work, with the most commonly used being a thin film of the semiconductor, indium-tin oxide, on glass. 

ECDs operate in the diffuse reflectance mode and the basic requirements for their functionality are (i) a primary electrochromic electrode (e.g. a polymer electrode) deposited on a substrate which is both optically transparent and electrically conducting (generally indium-tin-oxide(ITO)-... 

The electrochemical approach discussed here relies on a number of special properties of indium tin-oxide (ITO) electrodes, which had been used in particular for spectroelectrochemistry since ITO is optically transparent and can be fabricated on glass [28, 29]. The first important attribute of ITO is the ability to access potentials up to about 1.4 V (all potentials versus SSCE) in neutral solution [29]. Second, ITO electrodes do not adsorb DNA appreciably [30], which could be anticipated from the ability of metal oxides to adsorb cationic proteins [31] polyanionic nucleic acids were therefore not expected to adsorb. This property makes ITO quite different from carbon, which allows access to relatively high potentials but strongly adsorbs DNA [32]. Third, the direct oxidation of guanine at ITO is extremely slow, even... 

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