Voltammetry with forced flow of the solution towards the
electrode surface.
Notes: - Mass transport of a redox species enhanced by convection in this way results in a greater electric current. Convective mass transfer occurs up to the diffusion-limiting layer, within which the mass transfer is controlled by diffusion. Electroactive substance depletion outside the diffusion layer is annulled by convective mass transfer, which results in steady-state sigmoidal wave-shaped current-potential curves.
- A linear potential scan, at sufficiently slow scan rates so as to ensure a steady state response, is usually applied.
- The forced flow can be accomplished by movement either of the solution (solution stirring, or channel flow), or of the electrode (electrode rotation or vibration).
Examples: - Voltammetry at a rotating disc electrode (RDE): the limiting current is described by the Levich equation.
- Measurement in flowing systems with electrochemical detection (ED) (high performance liquid chromatography - ED, capillary zone electrophoresis - ED, flow injection analysis - ED).
Source:
PAC, 2020, 92, 641. 'Terminology of Electrochemical Methods of Analysis (IUPAC Recommendations 2019)' on page 673 (https://doi.org/10.1515/pac-2018-0109)