Anthracene, heterogeneous oxidation

The early applications of fast CV mainly focused on the measurement of the peak-potential separation, AEp, for the reduction or oxidation process of aromatic compounds, to obtain the pertinent standard heterogeneous rate constant k° from the relationship given in Table 2 [22]. The largest k° values of about 4 cm s were found for the reduction of aromatic hydrocarbons such as anthracene at a gold electrode in acetonitrile. The peak-potential separation increased from the 58 mV expected for a reversible process at low v to about 100 mV on going to v values of 10 kV s . This also shows that there is no real need for employing extremely large sweep rates in the determination of k° for the majority of compounds. Rather, it is important to ensure that the measurements at the lower sweep rates are not hampered by the contribution from spherical diffusion if a too small UME is used. 

Clegg AD, Rees NV, Klymenko OV, Coles BA, Compton RG (2004) Marcus theory of outer-sphere heterogeneous electron transfer reactions dependence of the standard electrochemical rate constant on the hydrodynamic radius from high precision measurements of the oxidation of anthracene and its derivatives in nonaqueous solvents using the high-speed channel electrode. J Am Chem Soc 126(19) 6185-6192... 

Revolutionary incursion of microelectrodes seems to be the most evident improvement of LSV and CV. The short-range diffusion enables direct plotting of virtual steady-state I — E curves in time intervals less than 1 min with maximum deviation not exceeding 2%. The small interfacial area of microelectrodes results in low interphase capacitance and a corresponding small time constant. This fact permits measurements on the microsecond time scale (cf. [131]). The computer-con-trolled system described in [121] makes possible to evaluate heterogeneous rate constants of 10 m s" order, e.g., for the oxidation of ferrocene or anthracene in acetonitrile. 

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