The potentials of zero charge of Pd(111) and thin Pd overlayers on Au(111)

The potential of zero charge (pzc) of Pd(111) has been determined in dilute NaF solutions by measuring the Gouy-Chapman minimum of the double-layer capacity. For a massive Pd(111) single crystal electrode a pzc of -0.12 V vs. SCE has been found. The corresponding values for thin Pd(111) overlayers on Au(111) have also been determined. While the pzc of the first, pseudomorphic Pd layer on Au(111) is -0.09 V vs. SCE, the pzc of a five monolayers thick Pd film on Au(111) is practically identical to the pzc of the massive Pd(111) electrode. By comparing pzc's and work functions for Au(111) and Pd(111), the dipole contribution to the potential drop across the Pd(111)/water interface is estimated. (C) 2002 Elsevier Science B.V. All rights reserved.