Electrocatalytic reactivity for oxygen reduction at epitaxially grown Pd thin layers of various thickness on Au(111) and Au(100)

Electrochemical reduction of oxygen was studied at the epitaxially grown ul tra thin Pd layers of various thicknesses on Au(111) and Au(100) single cry stal surfaces in 50 mM HClO4 solution saturated by oxygen. The oxygen reduc tion at the Pd thin layers on the gold substrate started at more positive p otential than that at the gold single crystal surfaces even only a submonol ayer of Pd was deposited. The potentials where cathodic current of oxygen r eduction started to increase were dependent on the potentials where the oxi de of the ultra thin Pd layers was reduced. (C) 2000 Elsevier Science Ltd. All rights reserved.