Hydrodynamic modulation at a rotating disc electrode

A theoretical treatment is presented for experiments involving hydrodynamic modulation at a disc electrode. Analytical expressions are obtained for the phase shift and amplitude of the current compared to those of the rotation speed for both potentiostatic and galvanostatic experiments. The theoretical expressions are found to be in good agreement with previous numerical and experimental results. [1,2]. Expressions are also obtained for the response of the disc current to a step function in rotation speed. Good agreement with experiment is found. This experiment is a general method of measuring diffusion coefficients without having to know the concentration of the electroactive species.