Underpotential Deposition and Stripping of Lead at Disorganized Monolayer-Modified Gold Electrodes

Abstract

Underpotential deposition (UPD) and stripping of Pb2þ at thiol-based disorganized monolayer-modified gold electrodes was studied by cyclic voltammetry (CV) and electrochemical quartz crystal microgravimetry (EQCM). Electrodes modified with mercaptoacetic acid or mercaptoethane sulfonic acid were studied. Due to the proximity of the potentials for the Pb UPD and thiol reductive desorption, achievement of a UPD-stripping voltammetry methodology for determination of low concentrations of Pb2þ was not successful. However by comparison of the CV and EQCM data and consideration of the possible mass changes per mole electrons transferred in light of the other species present in solution, possible mechanisms are put forward for the deposition and stripping of Pb2þ at thiolmodified electrodes.