Exxon's Sinfelt Wins 1984 Perkin Medal for Catalysis Research

Simulation of the Polarization Curves for Oxygen Reduction at a Rotating Disk Electrode

“…Table I is a list of parameter values used to simulate the electrochemical reduction of oxygen in 1.0M NaOH solution at 25~ Diffusion coefficient and solubility data for 02 in KOH (24,25) were used since literature values for NaOH were not readily available. The simulation was carried out for (i) the overall reaction scheme for the re- [2], [3], and [4], (ii) the parallel mechanism without peroxide decomposition, given by Eq. [1], [2], and [3], (iii) the consecutive mechanism with and without peroxide decomposition given by Eq.…”

“…The simulation was carried out for (i) the overall reaction scheme for the re- [2], [3], and [4], (ii) the parallel mechanism without peroxide decomposition, given by Eq. [1], [2], and [3], (iii) the consecutive mechanism with and without peroxide decomposition given by Eq. [2], [3], and [4] and Eq.…”

“…At certain values of the kinetic parameters, reaction [1] dominates the competition for 02 at the electrode. Consequently, the fraction of O~ going through the peroxide step by reactions [2] and [3], will be small compared to the former case. The direct 4e-process will prevail and as shown in Fig.…”

“…6-8, a single plateau corresponding to the limiting current density of the 4e process is observed. On the other hand, if reaction [2] dominates the competiton for O~, the two-step 2e-process is likely to prevail, resulting in a polarization curve with a limiting current density corresponding to the 2e-process at lower values of the applied potential and possibly another limiting current density plateau corresponding to the 4e-process at higher values of the applied potential. Between these two extreme cases, polarization curves corresponding to the simultaneous participation of the direct 4e-process and the two-step 2e-process are ob- served.…”

“…This reaction also plays a special role in the corrosion of metals. Other areas in which the reaction has attracted special attention are the production of hydrogen peroxide for use in the pulp and paper industry (2), the development of oxygen depolarizer cathodes for the replacement of hydrogen generating cathodes in the chlor-alkali industry (3), and the extraction of oxygen from air (4).…”