Kinetics and mechanism of oxygen electroreduction in alkaline solutions on xc-72r carbon black modified by products of pyrolysis of cobalt 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin

Cathodic oxygen reduction on XC-72R carbon black modified by products of pyrolysis of cobalt 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin (CoTMPP) (XC-72M) was studied. When XC-72R carbon black is modified, new active centers (ACs) are formed on the surface of the carbon support, on which the direct reaction to OH^- occurs, as shown using the rotating ring-disk electrode technique. The process of oxygen reduction on nonmodified carbon black occurs via the serial path. At low polarizations, the dependence of potential on pH corresponds to the slope of ??30 mV both for the carbon material and modified carbon black. This value is close to the coefficient in the Nernst equation for H₂/HO ₂ ^? . The slow stage of oxygen reduction is the transfer of the first or second electron to the adsorbed molecule. Herewith, the difference in the kinetics and mechanism of oxygen reduction on XC-72R and XC-72M is related to a stronger adsorption interaction of oxygen and ACs on XC-72M. The {ie1113-1} value in the pH range of 12?C14.6 is ?15 to ?20 mV both for XC-72R and XC-72M. In the case of the second halfwave potential on XC-72R, it is ?50 to ?60 mV. The observed effects are explained by a change in the surface state of catalysts at an increase in adsorption of OH^? ions at an increase in pH.