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

The effect of uncompensated resistance, Ru, 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, Epeak − E0′, the peak current, ipeak, and uncompensated resistance, Ru, can be correlated by a simple, general, empirical expression:Epeak-E0′ipeakRu≅2-exp-2.612nFRTEpeak-E0′-0.764.When the value of (nF/RT)∣Epeak − E0′ ∣ ⇒ 0, (Epeak − E0′)/ipeakRu ⇒ 2; when the value of (nF/RT)∣Epeak − E0′∣ ⇒ ∞ the value of (Epeak − E0′)/ipeakRu ⇒ 1.0; these limiting values are independent of the double layer capacitance, Cdl. For intermediate values this expression is adequately accurate as long as RTCdl/n2F2Γtotal ⩽ 0.1.