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.