where J is the measured current density, JK and JL are the kinetic and limiting current densities, ω is the angular velocity of the disk, n is the overall number of electrons transferred in oxygen reduction, F is the Faraday constant (96485 C/mol), C0 is the bulk concentration of O2 (1.2 × 10-6 mol cm-3), D0 is the diffusion coefficient of O2 in 0.1 M KOH (1.9 × 10 -5 cm 2 s -1 ), and V is the kinematic viscosity of the electrolyte (0.01 cm 2 s -1 ).