Liu, Y.; Aoki, K.J.; Chen, J. Similarity of Heterogeneous Kinetics to Delay of Double-Layer Capacitance Using Chronoamperometry. Electrochem2023, 4, 301-312.
Liu, Y.; Aoki, K.J.; Chen, J. Similarity of Heterogeneous Kinetics to Delay of Double-Layer Capacitance Using Chronoamperometry. Electrochem 2023, 4, 301-312.
Liu, Y.; Aoki, K.J.; Chen, J. Similarity of Heterogeneous Kinetics to Delay of Double-Layer Capacitance Using Chronoamperometry. Electrochem2023, 4, 301-312.
Liu, Y.; Aoki, K.J.; Chen, J. Similarity of Heterogeneous Kinetics to Delay of Double-Layer Capacitance Using Chronoamperometry. Electrochem 2023, 4, 301-312.
Abstract
Chronoamperometric curves of the oxidation of a ferrocenyl derivative by the potential step showed diffusion controlled-like currents less than the Cottrell's equation at a platinum wire electrode. The lower deviation cannot be explained by the Butler-Volmer heterogeneous kinetics, but was ascribed to the negatively capacitive current associated with the redox reaction. The deviation at the fully oxidized potential corresponds to the non-zero concentration at the electrode surface, which cannot be predicted from the Nernst equation. The Nernst equation expresses the relationship of the potential with the activity at the electrode surface rather than the concentration. The diffusion equation provides the relation of the current with the surface concentration rather than the activity. The negative capacitance or the non-zero concentration may arise from structure formation on the electrode owing to the dipole-dipole interaction, which is similar to the generation of the double layer capacitance including frequency dispersion. On this concept, we derive here expressions for the lowered diffusion-controlled current and the time-dependent surface concentration. The negatively capacitive current shows the time-dependence of t-0.9, which is similar to the decay of the double layer capacitive currents. The surface concentration decays with the t-0.4-dependence.
Keywords
heterogeneous kinetics; Butler-Vomer type; delay of the double layer capacitance; frequency dispersion; chnoroanperometry; ferrocenyl derivative; lowered diffusion-controlled current; time-dependent surface concentration; negatively capacitive current
Subject
Chemistry and Materials Science, Analytical Chemistry
Copyright:
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