Solvent effects on the kinetics of simple electrochemical reactions

摘要: Abstract The electroreduction kinetics of Co(en) 3 3+ (en-ethylenediamine), Co(NH ) 6 , and 5 F 2+ have been investigated atmercury electrodes in aqueous solution six nonaqueous solvents order to explore the influence solvent upon electrode such simple one-electron outer-sphere reactions where composition reactant's coordination sphere remains fixed. Substantial variations experimental rate parameters were observed as was altered; these reflect outer-shell reorganization barrier electron transfer. A phenomenological treatment effects redox is given. It pointed out that double-layer corrected constants k corr can be evaluated at same Galvani potential different with useful accuracy; quantities provide particular insight into chemical solvent. utility separating “intrinsic” “thermodynamic” contributions noted. substantial decreases seen when substituting several non-aqueous for water, traced increases component intrinsic free-energy (Δ G i # os . In contrast, small are predicted by dielectric continuum model under circumstances. These discrepancies between theory experiment ascribed from extensive short-range reorientation molecules. Variations efficiency tunneling within transition state may also a contribution effects.