Electrocatalysis of oxygen reduction on Co3O4 and PbCo5Ox synthesized by sol-gel

Co3O4 and PbCo5Ox have been synthesized by the sol-gel method These oxides supported on carbon paste were studied for oxygen reduction in alkaline sol ution (0.5 M KOH), by rotating disc electrode (rde) and rotating ring-disc electrode (rrde) techniques. The surface morphology was studied by scanning electron microscope (SEM), showing a grain size of a 0.5 to 3 mu m. X-ray diffraction pattern (XRD) showed poorly crystallized oxides. From the poten tiodynamic behavior, the kinetic parameters were deduced. Tafel slopes of - 0.103 and -0.124 V dec(-1) were determined for Co3O4 and PbCo5Ox, respectiv ely. Oxygen reduction proceeds via a four-electron transfer reaction, follo wing the reaction pathway: O-2 + 2H(2)O + 4e(-) = 40H(-). These oxides offe r promise as oxygen reduction electrocatalyst combining high activity with good stability.