Abstrato

Quasi-reversible two-electron reduction of oxygen at the reagent-less in situ modified gold electrodes

Md.Rezwan Miah, Md.Nazmul Alam, Md.Shahin Sarkar

Polycrystalline gold (Au (poly)) electrode was in situmodified inmother electrolyte of 0.1MKOHsolution (excluding the addition of other reagents) under stirring the solution with N2 gas for several minutes. Adsorption of some unknown species and enhancement of the chemisorption of OH- ions onto the electrode surface were electrochemically detected. The modified electrode was used for oxygen reduction reaction (ORR). The striking feature of the ORR at the modified electrode is that it transforms the irreversible ORR (at the cleanAu (poly)) into a quasi-reversible reaction with respect to the O2/HO 2 couple having formal potential (E) of -137mV, peak separation (Ep)-126mVand the ratio of cathodic peak current to anodic one ca. 0.9. The cathodic transfer coefficient (c) and heterogeneous electron transfer rate constant (ks) were calculated as 0.36 and 0.45 s-1, respectively.