Quasi-reversible two-electron reduction of oxygen at iodine submonolayer-coated gold electrode in alkaline media

Oxygen reduction reaction (ORR) was investigated using polycrystalline gold (Au (poly)) electrode modified with chemisorbed iodine (I(ads)) submonolayer (sub I(ads)) in O2-saturated 0.1 M KOH solution. The sub I(ads) was tailored by potential-dependent partial reductive desorption of I(ads) from its full monolayer. The Au (1 1 1) facet of the Au (poly) electrode was considered to remain bared at the sub I(ads)/Au (poly) electrode. The interesting finding of the present study is that (unlike the bare Au (poly) electrode) the sub I(ads)/Au (poly) electrode exhibited a quasi-reversible two-electron reduction of O2 in alkaline media. The probable origin of the observed quasi-reversible behavior of the ORR is discussed. Experimental investigations were performed using cyclic and steady-state voltammetric, amperometric and coulometric techniques.