Platinum electrodes double layers

Climent V, Gomez R, Orts JM, Aldaz A, Fehu JM. 1997. The potential of zero total charge of single-crystal electrodes of platinum group metals. In Korzeniewski C, Conway BE, eds. The Electrochemical Society Proceedings (Electrochemical Double Layer). Pennington, NJ The Electrochemical Society, pp. 222-237. 

Climent V, Coles BA, Compton RG, Feliu JM. 2004. Coulostatic potential transients induced by laser heating of platinum stepped electrodes Influence of steps on the entropy of double layer formation. J Electroanal Chem 561 157-165. 

Kunimatsu K, Golden WG, Seki H, Philpott MR. 1985a. Carbon monoxide adsorption on a platinum electrode studied by polarization modulated FT-IRRAS. 1. Co Adsorbed in the double-layer potential region and its oxidation in acids. Langmuir 1 245 -250. 

The processes classified in the third group are of primary importance in elucidating the significance of electric variables in electrosorption and in the double layer structure at solid electrodes. These processes encompass interactions of ionic components of supporting electrolytes with electrode surfaces and adsorption of some organic molecules such as saturated carboxylic acids and their derivatives (except for formic acid). The species that are concerned here are weakly adsorbed on platinum and rhodium electrodes and their heat of adsorption is well below 20 kcal/mole (25). Due to the reversibility and significant mobility of such weakly adsorbed ions or molecules, the application of the i n situ methods for the surface concentration measurements is more appropriate than that of the vacuum... 

Variations of resistance with frequency can also be caused by electrode polarization. A conductance cell can be represented in a simplified way as resistance and capacitance in series, the latter being the double layer capacitance at the electrodes. Only if this capacitance is sufficiently large will the measured resistance be independent of frequency. To accomplish this, electrodes are often covered with platinum black 2>. This is generally unsuitable in nonaqueous solvent studies because of possible catalysis of chemical reactions and because of adsorption problems encountered with dilute solutions required for useful data. The equivalent circuit for a conductance cell is also complicated by impedances due to faradaic processes and the geometric capacity of the cell 2>3( . 

In the particular cell (Fig. 6.28) generated by the measuring process, it will be only as a special case that the metal Mj (of the electrode/electrolyte interface under study) is identical with the metal M2 (the connecting wires of the measuring instrument). In general, M, and M2 will be different metals, say, platinum and copper. The meeting of the platinum and copper phases produces another double layer and an... 

Thus, when a substituent of interest is incorporated into an olefinic substance and the resulting compound allowed to react with the electrode surface, the substituent becomes connected to the surface.. .. By this means, ionic species have been tethered within the double layer region in order to probe the mechanisms of electrode reactions involving platinum complexes.. . . Alternatively, the electrochemical reactant itself can be connected to the electrode surface, allowing its reactivity to be observed as a function of charge, orientation, and structure, as described here. 

For an electrophysiological experiment you form an electrode from a 5 cm long platinum wire (0.4 mm diameter) by bending it in the shape of a spiral. Calculate the total capacitance of the diffuse electric double layer for aqueous solutions of a monovalent salt at concentrations of 0.1 and 0.001 M. Assume a low surface potential. 

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