Electrocatalysis, modification

Kohei Uosaki received his B.Eng. and M.Eng. degrees from Osaka University and his Ph.D. in Physical Chemistry from flinders University of South Australia. He vas a Research Chemist at Mitsubishi Petrochemical Co. Ltd. from 1971 to 1978 and a Research Officer at Inorganic Chemistry Laboratory, Oxford University, U.K. bet veen 1978 and 1980 before joining Hokkaido University in 1980 as Assistant Professor in the Department of Chemistry. He vas promoted to Associate Professor in 1981 and Professor in 1990. He is also a Principal Investigator of International Center for Materials Nanoarchitectonics (MANA) Satellite, National Institute for Materials Science (NIMS) since 2008. His scientific interests include photoelectrochemistry of semiconductor electrodes, surface electrochemistry of single crystalline metal electrodes, electrocatalysis, modification of solid surfaces by molecular layers, and non-linear optical spectroscopy at interfaces. 

Professor in 1981 and Professor in 1990. He is also a Principal Investigator of International Center for Materials Nanoarchitectonics (MANA) Satellite, National Institute for Materials Science (NIMS) since 2008. His scientific interests include photoelectrochemistry of semiconductor electrodes, surface electrochemistry of single crystalline metal electrodes, electrocatalysis, modification of solid surfaces by molecular layers, and non-linear optical spectroscopy at interfaces. 

Carbonaceous Surfaces Modification, Characterization, and Uses for Electrocatalysis... 

It has been often stressed that low eoordinated atoms (defeets, steps, and kink sites) play an important role in surfaee ehemistry. The existenee of dangling bonds makes steps and kinks espeeially reaetive, favoring the adsorption of intermediate species on these sites. Moreover, smdies of single-crystal surfaces with a eomplex geometry have been demonstrated very valuable to link the gap between fundamental studies of the basal planes [Pt( 111), Pt( 100), and Pt(l 10)] and applied studies of nanoparticle eatalysts and polycrystalline materials. In this context, it is relevant to mention results obtained with adatom-modified Pt stepped surfaces, prior to discussing the effect of adatom modification on electrocatalysis. 

Schmidt TJ, Stamenkovic V, Arenz M, Markovic NM, Ross PN. 2002. Oxygen electrocatalysis in alkaline electrolyte VtQikl), AuQikl) and the effect of Pd-modification. Electrochim Acta 47 3765-3776. 

Modification of electrodes by electroactive polymers has several practical applications. The mediated electron transfer to solution species can be used in electrocatalysis (e.g. oxygen reduction) or electrochemical synthesis. For electroanalysis, preconcentration of analysed species in an ion-exchange film may remarkably increase the sensitivity (cf. Section 2.6.4). Various... 

The reader may notice many cross-references between the five contributions, which support the view that chemical modification of surfaces, particularly the nanostructuring, is not only interesting for its own sake, but also relevant to a wide range of practice applications. Their seminal role in bioelectrochemistry, bio-sensing, electrocatalysis and electroanalysis among others is clearly evident in this volume. 

Additional information about this Fc GO preparation has been reported elsewhere (112). The intramolecular electron transfer rate constant kmirn calculated using Eq. (36) equals 40 s-1 and is by a factor of 50 higher than that for the randomly modified GO (104). The distance separating the ferrocene unit and FAD in Fc GO is believed to be ca. 19 A, by 2 A shorter than in the most effective electrically contacted enzyme generated by the random modification of GO by ferrocene units. This information supports the hypothesis about the key locations of ferrocene groups that play the dominant role in the electrocatalysis (104). 

Work on the modification of electrode surfaces is of more recent origin, but the research has already gathered considerable momentum. Coordination compounds have not played a unique role in this development, but they have on occasion made important advances possible. Some authors believe that this work will influence the direction of electrochemistry for many years to come. It certainly has implications for electrocatalysis, electronic devices, visual display units and photoelectricity to mention but a few topical objectives which currently drive the research. 

P.M. Armistead and H.H. Thorp, Modification of indium tin oxide electrodes with nucleic acids detection of attomole quantities of immobilized DNA by electrocatalysis, Anal. Chem., 72 (2000) 3764-3770. 

The modification of electrode surfaces with electroactive polymer films provides a means to control interfacial characteristics. With such a capability, one can envisage numerous possible applications, in areas as diverse as electronic devices, sensors, electrocatalysis, energy conversion and storage, electronic displays, and reference electrode systems [1, 2]. With these applications in view, a wide variety of electroactive polymeric materials have been investigated. These include both redox polymers (by which we imply polymers with discrete redox entities distributed along the polymer spine) and conducting polymers (by which we imply polymers with delocalised charge centres on the polymer spine). 

Surface modification of electrodes to facilitate electrocatalysis parallels in many respects the chemistry discussed above for immobilization of catalysts on organic and inorganic materials. However, the objectives are somewhat different in electrode modification. Specifically, the principle objectives in electrode modification are usually to alter electrode stability, to alter the kinetics of reactions at electrode surfaces, or to alter an electrodes electrochemical properties. Electrode modification may involve covalent attachment of electroactive compounds or coating of the electrode surface with a polymeric phase. 

Modifed electrodes have many potential applications. A primaiy interest has been in the area of electrocatalysis. Here, electrodes capable of reducing oxygen to water have been sought for u.se in fuel cells and batteries. Another potential application is in the production of electrochromic devices that change color on oxidation and reduction. Such devices could be used in displays or smtin win-... 

The general concept of chemical modification [55, 56] of electrode surfaces can be attributed by and large to the seminal work of Hubbard and co workers [57] in the early 1970s. Since then, electrode surfaces modified by a wide variety of adsorbed species, including polymers and other types of films have received wide attention not only in electrocatalysis, but also in sensor technology and other applications. 

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