EQCM study of electrochemical modification of Bi2S3 films in the Zn2+-containing electrolyte

The electrochemical behavior of Bi2S3 as-deposited on Au using the successive ionic layer adsorption and reaction method has been investigated in the Zn2+-free background and Zn2+-containing electrolytes at different pH by electrochemical quartz crystal microbalance coupled with cyclic voltammetry and Xray photoelectron spectroscopy. It has been shown that when the Bi2S3 film is reduced in the Zn2+-containing electrolyte Zn2+ ions are involved in electrochemical bismuth sulfide reduction and are partially reduced together with the bismuth sulfide film. The bismuth sulfide film initiates the adsorbed Zn2+ ions reduction prior to the traditional overpotential deposition of it. Reduction of Zn2+ ions prior to the overpotential deposition of Zn depends on solution pH: at pH 5 it occurs at more negative potential values and the observed mass changes due to Zn electrodeposition are greater than at solution pH 3. After bismuth sulfide film reduction in the Zn2+-containing electrolyte, Zn was detected as ZnO and metallic Zn at pH 5, while at pH 3 only ZnO was detected. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.