Electrochemistry general mechanism

Recovery of metals such as copper, the operation of batteries (cells) in portable electronic equipment, the reprocessing of fission products in the nuclear power industry and a very wide range of gas-phase processes catalysed by condensed phase materials are applied chemical processes, other than PTC, in which chemical reactions are coupled to mass transport within phases, or across phase boundaries. Their mechanistic investigation requires special techniques, instrumentation and skills covered here in Chapter 5, but not usually encountered in undergraduate chemistry degrees. Electrochemistry generally involves reactions at phase boundaries, so there are connections here between Chapter 5 (Reaction kinetics in multiphase systems) and Chapter 6 (Electrochemical methods of investigating reaction mechanisms). 

There are some major differences between electrochemical engineering and classical electrochemistry. In conventional electrochemistry the mechanism of the electrode process and its kinetics are often the factors of major concern whereas in electrochemical engineering the actual mechanistic details of the process are usually less important than its specificity or process efficiency. The rate of the process defined either as current efficiency or as a general measure of reactor efficiency, the space-time yield are the main performance criteria. This latter factor determines whether a process is economically or commercially viable since it can be used to compare performance of different electrode designs as well as comparing an electrochemical process with the space-time yields for alternate non-electrochemical technologies. 

As on previous occasions, the reader is reminded that no very extensive coverage of the literature is possible in a textbook such as this one and that the emphasis is primarily on principles and their illustration. Several monographs are available for more detailed information (see General References). Useful reviews are on future directions and anunonia synthesis [2], surface analysis [3], surface mechanisms [4], dynamics of surface reactions [5], single-crystal versus actual catalysts [6], oscillatory kinetics [7], fractals [8], surface electrochemistry [9], particle size effects [10], and supported metals [11, 12]. 

Among well-known medical devices are the mechanical heart valve and the pacemaker. Although medical devices are generally perceived as being either macroscopic or permanent, many, and in some cases all, of the effects (wanted and unwanted) of the devices are derived from interactions at the surface. Indeed, when the devices are made of metals, many, if not most, of the surface effects are electrochemical in nature. This fact is the main subject of this chapter whose role is to outline briefly the manner in which electrochemistry and thus electrochemical deposition are crucial to both the mechanical and materials stability of medical devices. In some cases, entirely new industries have been created around advances in our understanding of the electrochemical processes occurring at surfaces. An additional aim of this chapter is to touch on the ways in which electrochemistry can be used to modify surfaces actively to create a more amicable... 

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