Jaynal Abedin Molla

THE EFFECT OF PH ON THE ELECTROCATALYTIC PROPERTIES OF ADSORBED METAL IONS

The electrocatalytic behavior of adsorbed lead atoms on mercury towards O2 reduction in neutral electrolyte at ambient temparature is examined. The results shows that O2 reduction on these modified surfaces proceeds through the series mechanism and that the enhancement is mainly due to hydrogen peroxide elimination through reduction and/or heterogeneous chemical decomposition. Measurements performed as a function of pH in the range pH = 4 to pH = 10 indicate that the hydrogen peroxide decomposition reaction slows down as the pH increases. Using cyclic voltammetry and rotating ring-disk techniques, it is demonstrated that for the PbHg system the catalytic species is lead oxide or lead hydroxide.