Indirect values redox electrodes

Typically, the reference level for the solution redox potential is chosen to be the normal hydrogen electrode (NHE). Some tabnlations nse the saturated calomel electrode (SCE) as the reference level with the difference between these two scales well-known to be NHE = —0.2412 V versus SCE. The fundamental problem lies in the determination of the absolnte energy of the NHE relative to vacuum. Although a method to determine directly the absolute electrochemical potential of an NHE has not yet been described, a recent indirect measnrement has indicated that it is approximately 4.4 eV below the vacnum level. This value is often used to relate the solution electrochemical potential scale to the solid electrochemical potential scale. It provides the best approximation that is presently available to calculate the... 

A fundamental reason for measuring rates of electron transfer (ET) is to identify the physical-chemical factors that control those rates and to learn how to control those factors. For the past several years we have focused our experimental efforts on the measurement of the heterogeneous electron-transfer rate constant, k° (units s ), for systems where the redox species are covalently attached to the electrode by any of a variety of molecular tethers [1-3]. The indirect laser-induced temperature method, which we developed [4-6], has the capability of measuring k° values as large as 10 s and has proven to be ideally suited for these types of studies. We will show some recent development that we anticipate will allow the measurement of k° values greater than 10 s . ... 

EAB processes are an interfacial phenomenon EABs interact with the electrode inside the biofilm diffusive and reactive layers at the electrode surface. Extracellular electron transfer is directly related to these microscale layers, whereas diffusion processes above these layers are linked indirectly. Thus, we expect that the surface concentrations of the redox-active compounds and the local solution properties inside EABs are more relevant and critical than the corresponding values in the bulk. Correlating and fitting lines to bulk data may have little significance to the fundamental processes occurring inside EABs. Direct measurements inside EABs are preferred, such as measuring pH inside EABs or measuring the spectroelectrochemical properties of EABs [66, 138, 147]. This is especially important because the cell density inside some EABs is not uniformly distributed and predictions based on simple diffusion may not apply [120]. 

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