Platinum electrodes complex molecules

Deviations from the E1/2-DN curves may occur with EPD molecules which can coordinate in different ways. For instance, nitrobenzene coordinates towards SbCls via an oxygen atom of the nitro group, while towards a soft EPA cation coordination via the aromatic ring appears possible. In the latter case E1/2 values would be determined not by the donicity (97) (measured towards SbCls) but by the r-donor properties of nitrobenzene. Studies of the reduction of Ag+ at the rotating platinum electrode in various EPD solvents indicate that nitrobenzene behaves as a stronger EPD than expected on basis of its donicity 39). In fact, Ag+ forms complexes with various aromatic compounds 46). Specific EPD—EPA interactions were observed in the reduction of Cu+, Ag+... 

Lane, R. T., and Hubbard, A. T. Electrochemistry of chemisorbed molecules. 11, The iiitlu-ence of charged chemisorbed molecules on the electrode reaction.s of platinum complexes. /. Phys. Chem. 1973, 77, 1411-1421. 

Improved kinetics at the positive electrode. The electrochemical reduction of oxygen is also a complex process each molecule requires the transfer of four electrons for complete reduction. Surface intermediates are formed and these lower the kinetic performance of the electrode. Platinum-based electrocatalysts are necessary to allow the reaction to proceed at a useful rate. A more effective and cheaper alternative electrocatalyst is an ongoing research target, as is equally the case for positive electrodes in PEMFCs. 

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