Electrochemical quartz crystal microbalance study on cyclic electrodeposition of PbS thin-films

Electrochemical quartz crystal microbalance combined with cyclic voltammetr y was used to study the electrodeposition of PbS thin-films on Au surface. The electrodeposition was carried out by cycling between two potentials wit h voltage scan rates of 0.1 and 0.01 V/s. In addition, the electrochemical behaviour of PbS film and the related precursors, PbEDTA(2-) and HS- were s tudied separately. It was found that the reduction of PbEDTA(2-) occurred a t a more positive potential on the PbS surface than on the Au surface. Simi larly, HS- oxidised at a more negative potential on the PbS than on the Au surface. Therefore, the deposition of PbS was proposed to occur by two mech anisms. The first mechanism includes the reduction of PbEDTA(2-) to element al lead which during the oxidation reacts with HS-. In the other mechanism, PbS surface induces the chemical reaction between PbEDTA(2-) and HS. The e lectrodeposited PbS is stable in the potential range of -1.2 to -0.2 V vs. Ag/AgCl, (C) 2001 Elsevier Science B.V. All rights reserved.