Electrochemistry catalysis

Further Chemical Reactions of Noble Metal Porphyrins Notes on Electrochemistry, Catalysis, and Other Applications... 

The physical and chemical behavior of metal surfaces has been of interest ever since metals were put into use thus metal surfaces have been studied for a much longer period and to a greater extent that semiconductor surfaces. Over the years, studies of metal surfaces played an important role in such fields as metallurgy, electrochemistry, catalysis, and... 

To date, carbon materials play a major role in nanosciences (fullerenes, nanotubes), electronic industry (diamond), metallurgy (graphitic carbon), electrochemistry, catalysis, adsorption, etc, The majority of these applications have arisen because of the existence of a superficial layer of chemically bonded elements. Thus, the surface functional groups determine the self-organization, the chemical stability and the reactivity in adsorptive and catalytic processes. 

Electrochemical promotion (EP) denotes electrically controlled modification of heterogeneous catalytic activity and/or selectivity. This recently discovered phenomenon has made a strong impact on modem electrochemistry/ catalysis/ and surface science. Although it manifests itself also using aqueous electrolytes/ the phenomenon has mainly been investigated in gas-phase reactions over metal and metal oxide catalysts. In the latter case, the catalyst, which is an electron conductor, is deposited in the form of a porous thin film on a solid electrolyte support, which is an ion conductor at the temperature of the catalytic reaction. Application of an electric potential on the catalyst/support interface or, which is equivalent, passing an electric current between catalyst and support, causes a concomitant change also in the properties of the adjacent catalyst/gas interface, where the catalytic reaction takes place. This results in an alteration of the catalytic behaviour, controllable with the applied potential or current. 

Choi WC, Kim DJ, Woo SI. Quaternary Pt-based electrocatalyst for methanol oxidation by combinatorial electrochemistry. Catalysis Today 2002 74 235-40. 

Oxides are very common in nature and play a fundamental role in corrosion, friction, electronic devices and superconductivity. The study of the properties of oxide surfaces has an interdisciplinary nature, being included in several fields of research - not only solid-state chemistry and physics, but also electrochemistry, catalysis, electronics and even geophysics and geology. Nowadays, nanostructured surfaces are used as substrates for growing artificial structures, for example, to make quantum wires or size-controlled clusters. 

Keywords Porphyrins Corroles Huorination Huoropyrroles Macrocycle synthesis Electrochemistry Catalysis... 

The scope of their applications has expanded over the years. They are attracting much interest in many fields of chemistry and industry due to their properties cited above. First seen as an alternative to volatile solvent, they are now used in electrochemistry, catalysis, asymmetric synthesis, extraction, chromatography... (Seddon, 1997 Sheldon, 1993 Cull et al, 2000 Wilkes, 2004 Wasserscheid Keim, 2000 Welton, 1999 Brennecke Maginn, 2001 Fredlake et al., 2004 Henderson Passerini, 2004). 

J. F. Rusling, Electrochemistry and Electrochemical Catalysis in Microemulsions, Plenum Press, 1994, Chapter 2. 

Of these, the most extensive use is to identify adsorbed molecules and molecular intermediates on metal single-crystal surfaces. On these well-defined surfaces, a wealth of information can be gained about adlayers, including the nature of the surface chemical bond, molecular structural determination and geometrical orientation, evidence for surface-site specificity, and lateral (adsorbate-adsorbate) interactions. Adsorption and reaction processes in model studies relevant to heterogeneous catalysis, materials science, electrochemistry, and microelectronics device failure and fabrication have been studied by this technique. 

RAIRS is routinely used for the analysis of chemically modified surfaces - surface systems in electrochemistry [4.277], polymer research [4.266, 4.278], catalysis [4.265, 4.271], selfassembling monolayers [4.267, 4.268], and protein adsorption [4.268, 4.279] have been investigated. 

The wide electrochemical windows of ionic liquids, in combination with their ability to serve as solvents for transition metal catalysts, opens up new possibilities for a combination of electrochemistry and transition metal catalysis. A very exciting first example has recently been published by Bedioui et al. [27]. 

Shimamura, K., Miura, K. Kawashima, A., Asami, K. and Hashimoto, K., Proc. Symp. on Corrosion, Electrochemistry and Catalysis of Metallic Glasses, (Diegle, R. B. and Hashimoto, K., eds.), the Electrochemical Society, Pennington, 232 (1980)... 

Models and theories have been developed by scientists that allow a good description of the double layers at each side of the surface either at equilibrium, under steady-state conditions, or under transition conditions. Only the surface has remained out of reach of the science developed, which cannot provide a quantitative model that describes the surface and surface variations during electrochemical reactions. For this reason electrochemistry, in the form of heterogeneous catalysis or heterogeneous catalysis has remained an empirical part of physical chemistry. However, advances in experimental methods during the past decade, which allow the observation... 

The importance of NEMCA in electrochemistry, surface science and heterogeneous catalysis has been discussed by Bockris,7 Wieckowski,8 Pritchard9 and Haber10 respectively. Electrochemical promotion, or NEMCA, has found its position in recent years as a separate section in practically all new general or graduate level textbooks on electrochemistry13,14 and catalysis.15... 

Due to the interdisciplinary nature of electrochemical promotion, which involves elementary but important concepts from at least five different fields (catalysis, surface science, electrochemistry, solid state ionics, chemical reaction engineering) we have structured the book in such a way to make it possible for readers from all the above fields to follow the entire book. 

Chapter 7 introduces the concept of absolute electrode potential in solid state electrochemistry. This concept has some important implications not only in solid state electrochemistry but also, potentially, in heterogeneous catalysis of supported catalysts. 

Work function, a quantity of great importance in surface science and catalysis, plays a key role in solid state electrochemistry and in electrochemical promotion. As will be shown in Chapter 7 the work function of the gas-exposed surface of an electrode in a solid electrolyte cell can be used to define an absolute potential scale in solid state electrochemistry. 

The electrochemical activation of catalysis, or electrochemical promotion of catalysis (EPOC), or electrochemical promotion, or NEMCA is an exciting phenomenon at the interface of catalysis and electrochemistry. 

---