EQCM Studies Of Effect Of Additives On Anodic Dissolution And Electrodeposition Of Some Metal

Electrochemical quartz crystal microbalance (EQCM) comprises a quartz crystal microbalance (QCM) combined with the electrochemical instruments. Because the EQCM technique takes the advantages of both the high sensitivity in electrochemical analysis and the in situ surface mass and viscosity sensitivity in the QCM system, it can simultaneously measure the changes of surface mass, current and quantity of charge in a potential scan, revealing more details for the electrochemical fuctions of the ion/ molecular on the electrode surface. At the same time, EQCM can response to the adsorption and desorption of non-electrochemically reactive species and allows us to determine the non-electrochemical process of electrode. Because the unique feature of EQCM, it was widely used in reaction mechanisms on metal electrodes, underpotential deposition of metals, conductive polymers, Biomedical and other fields.The conclusions of this study were:1、The theoretical knowledge、research progress and outlook of QCM and EQCM were reviewed.2、The anodic dissolution and electrodeposition of Cu and effected of1,1,3,3,-Tetramethylthiourea,NNO and Cl- on the processes in acidic media have been investigated by using cyclic voltammetry and EQCM. The experimental results demonstrate that the M/n values of the anodic dissolution and electrodeposition of Cu were 32.2 g / mol and 34.2 g / mol,respectively, showing only one wave corresponding to the 2-electron processes. No Cu+ ions, adsorbed Cu(I) species or intermediate Cu+ was evidenced by in situ EQCM measurements. 1,1,3,3,-Tetramethylthiourea may change the mechanism of the anodic dissolution and electrodeposition of Cu. The M/n values of the anodic dissolution and electrodeposition of Cu in the presence of 1,1,3,3,-Tetramethylthiourea were 63.8 g / mol and 61.7 g / mol,respectively, indicating the 1-electron processes and producing Cu(I) species. The mechanism of the anodic dissolution and electrodeposition of Cu has been put forward. NNO and Cl? both Inhibits the anodic dissolution and electrodeposition of Cu, but NNO and Cl? couldn’t synergistically inhibited the anodic dissolution and electrodeposition of Cu. 3、The influences of PTSA and Cl? on the underpotential deposition(UPD) and the overpotential deposition(OPD) of zinc on Fe/Pt electrode in acidic media were investigated by cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). The results demonstrated that PTSA and Cl? could both absorbe on Fe/Pt Electrode. When PTSA and Cl? coexisted, they promoted the desorption from the electrode each other. PTSA inhibited the underpotential deposition and the overpotential deposition of zinc. Cl? only inhibited the underpotential deposition of zinc but it could not effect the overpotential deposition of zinc. In the studied conditions, the processes of cathode deposition of Zn2+ all were 2- electron processes and PTSA and Cl? didn’t change the mechanism of the process of cathode deposition of Zn2+.4、The influence of NNO and sodium benzoate on the UPD of Zn2+ on Pt electrodes in acidic media was investigated by cyclic voltammetry and electrochemical quartz crystal microbalance. The results demonstrate that the UPD processes of zinc and H were simultaneously. NNO can both inhibit the UPD processes of zinc and H.NNO and sodium benzoate synergistically inhibited the UPD process of zinc.