SYSTEMATIC TRENDS IN THE CRYSTAL-FACE SPECIFICITY OF INTERFACIAL PARAMETERS - THE CASES OF AG AND AU

An aspect of electrochemistry which is not yet clarified in the literature is the crystal face dependence of the "interfacial parameter" X, which measures the variation of the electron work function PHI of a metal electrode as it comes into contact with the solution (at the potential of zero charge E(sigma=0)). Approaches proposed in the literature are scrutinized, in particular for Ag and Au single-crystal-face electrodes. Recent work function measurements for Ag and pairs of experimental data (PHI and E(sigma=0)) for the same crystal face of Au suggest that strictly quantitative conclusions cannot be reached in that no pairs of data for the same sample exist for Ag, while in the case of Au the pairs of data still refer to differently structured surfaces owing to reconstruction phenomena. Nevertheless, there is consistent evidence that for face-centred cubic metals the interfacial parameter increases in the sequence (111) < (100) < (110). This conclusion enables some predictions to be made for the crystal face specificity of other quantities, which are consistently verified.