Effect of Cl ions and benzylideneacetone/ethanol on the underpotential deposition of zinc in acidic media: cyclic voltammetry and EQCM studies

The influence of chloride ions and a benzylideneacetone (BDA)/ethanol (EtOH) mixture on the underpotential deposition (UPD) of Zn²⁺ ions on Pt electrodes in acidic media was investigated by cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). In the potential region of the UPD of H and Zn, the surface coverage of Zn adatoms on Pt was evaluated based on the correspondence between charge and mass for several different solutions. In the absence of Cl⁻ ions and BDA/EtOH, the maximum surface coverage of the Zn deposited by UPD was 0.29. In addition, in the presence of Cl⁻ ions, the UPD of Zn²⁺ ions occurred simultaneously with the adsorption of Cl⁻, and the presence of Cl⁻ did not modify the quantity of Zn deposited by UPD. In the presence of Cl⁻ ions and BDA/EtOH, the maximum surface coverage of the Zn deposited by UPD was 0.16. The partial inhibition of the UPD of Zn²⁺ ions is associated with the adsorption of BDA/EtOH or products of the decomposition of BDA/EtOH during the UPD process.