Effect of uncompensated resistance on the cyclic voltammetric response of an electrochemically reversible surface-attached redox couple: Uniform current and potential across the electrode surface

Abstract

The effect of uncompensated resistance, R u, on the cyclic voltammetric response of an electrochemically reversible surface-attached redox couple is quantified using simulation. When current density and interfacial potential are uniform across the electrode surface, the shift in the peak potential, E peak − E 0′, the peak current, i peak, and uncompensated resistance, R u, can be correlated by a simple, general, empirical expression: E peak - E 0 ′ i peak R u ≅ 2 - exp - 2.61 2 nF RT E peak - E 0 ′ - 0.764 . When the value of ( nF/ RT)∣ E peak − E 0′ ∣ ⇒ 0, ( E peak − E 0′)/ i peak R u ⇒ 2; when the value of ( nF/ RT)∣ E peak − E 0′∣ ⇒ ∞ the value of ( E peak − E 0′)/ i peak R u ⇒ 1.0; these limiting values are independent of the double layer capacitance, C dl. For intermediate values this expression is adequately accurate as long as RTC dl/ n 2 F 2 Γ total ⩽ 0.1.