Mechanism for nucleation and growth of electrochemical palladium deposition on an Au(111) electrode

Abstract

The initial kinetics of electrochemical deposition of palladium on an Au(111) electrode in 0.1 M H 2SO 4 solution containing K 2PdCl 4 have been investigated quantitatively by cyclic voltammetry (CV) and potentiostatic current transient measurements. A cathodic current maximum was observed in the initial stage of Pd deposition process in 0.1 mM K 2PdCl 4 solution. The analysis shows that the deposition of palladium in this solution proceeds by an instantaneous nucleation and two-dimensional (2D) growth mode. When the concentration of K 2PdCl 4 became higher, a potential-dependent cathodic current ‘plateau’ after the current maximum was observed. Simple nucleation-growth models cannot fit the transients in the region of the ‘current plateau’. The present current transient results were discussed in comparison with the results obtained by in situ scanning tunneling microscopy (STM).