Multiparametric electrochemical characterisation of Te–Cu–Pb atomic three-layer structure deposition on polycrystalline gold

Abstract

Successive underpotential deposition of Te ad, Cu ad and Pb ad adlayers in the potentiodynamic mode was used for Te ad/Cu ad/Pb ad atomic three-layer structure assembling on polycrystalline Au support. Layer-by-layer deposition was characterised in each of the stages with potentiodynamic electrochemical impedance spectroscopy (PDEIS) by variations, with the electrode potential E, of double layer pseudocapacitance Q dl, charge transfer resistance R ct and Warburg coefficient A of diffusion impedance. Q dl( E) has shown a strong decrease in the cathodic scan during Te atomic layer deposition on Au, a sharp peak in the subsequent Cu ad deposition on Au/Te ad and an increase in Pb ad deposition on Au/Te ad/Cu ad. The inverses of charge transfer resistance and Warburg coefficient have shown characteristic maxima in R ct - 1 ( E ) and A −1( E) dependencies in all the three stages of Te ad/Cu ad/Pb ad three-layer assembling. The characteristic features in the dependences on the potential of the ac response parameters compensated for insufficient self-descriptiveness of the dc part of the nonstationary interface response in the layer-by-layer deposition. High information density of PDEIS spectra provides better control of electrochemical processes on nonstationary interfaces and this new opportunity can enable wider use of electrochemical approaches for thin-layer structures preparation.