Accession Number : ADA294323

Title :   Rotating Microdisk Voltammetry in Low Ionic Strength Solutions.

Descriptive Note : Interim rept. Jun-Dec 94,

Corporate Author : UTAH UNIV SALT LAKE CITY DEPT OF CHEMISTRY

Personal Author(s) : Gao, Xiaoping ; White, Henry S.

PDF Url : ADA294323

Report Date : 31 MAR 1995

Pagination or Media Count : 30

Abstract : The influence of the supporting electrolyte concentration on the steady-state voltamnetric behavior of a 12.5 micrometers-radius rotating Pt disk electrode (angular velocity, (omega=0 to 378 radian/s) has been investigated for several electrochemical reactions in acetonitrile solutions. The results demonstrate that the voltammetric response is a strong function of the ratio of the supporting electrolyte and redox concentrations (C(sub elec)/C(sub redox)) as well as the charge of the reactant, (z). For the oxidation or reduction of monovalent and divalent species (e.g., (TRIMETHYLAMMONIO)METHYLferrocene (z = +1) and methylviologen (z = +2)), the observed voltammetric limiting currents are found to increase linearly with (0112,independent of C(sub elec)/C(sub redox). Voltammetric currents corresponding to the oxidation or reduction of neutral reactants (e.g., ferrocene and nitrobenzene (z = 0)) show a more complex dependence on C(sub elec)/C(sub redox). In solutions containing an appreciable quantity of supporting electrolyte, C(sub elec)/C(sub redux) > 0.1, mass-transport limited currents are found to increase linearly with omega (1/2). However, for C(sub elec)/C(sub redox) <0.1, the voltammetric currents decrease with increasing omega. The unusual behavior observed for neutral species in low ionic strength solution is interpreted in terms of the rate of migration of charge-balancing electrolyte ions to the electrode surface, relative to the rate of removal of the same ions by forced convection. jg

Descriptors :   *IONS, *VOLTAMMETRY, *ROTATION, VELOCITY, SOLUTIONS(MIXTURES), METHYL RADICALS, ACETONITRILE, NEUTRAL, CONVECTION, ELECTROCHEMISTRY, SURFACES, ELECTRODES, CHEMICAL REACTIONS, ORGANIC COMPOUNDS, IONIZATION, VALENCE, AMMONIUM COMPOUNDS, DISKS, ELECTROLYTES, LOW STRENGTH, CONCENTRATION(CHEMISTRY), REACTANTS(CHEMISTRY), OXIDATION REDUCTION REACTIONS, ANGULAR MOTION, FERROCENES.

Subject Categories : Physical Chemistry
      Inorganic Chemistry
      Organic Chemistry
      Electricity and Magnetism
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE