ToF-secondary ion mass-spectrometric study of copper deposition and stripping on directly heated screen-printed gold electrodes

We report about a new kind of directly heated gold electrode. All electrodes including a directly heated gold loop electrode, a Ag pseudo reference, and a carbon counter electrode have been screen-printed on a ceramic alumina substrate. Thermal behaviour was studied by potentiometry using either an external or the integrated reference electrode. Stripping voltammetric copper signals were greatly improved at elevated deposition temperature. Secondary ion mass spectrometric studies (ToF-SIMS) revealed that different negative ionic species of copper complexes can be found on the gold electrode surface as a result of ion bombardment during SIMS analysis like Cu^?, CuCl^? and CuCl₂ ^?. SIMS surface imaging using a fine focussed ion beam over the surface allowed us to obtain ion images (chemical maps) of the analyzed sample. SIMS depth profile analysis of the gold loop electrode was performed after copper deposition at room temperature (23 °C) and at 60 °C. CuCl₂ ^? ion was used for the depth profile studies as it has shown the highest intensity among other observed species. Surface spectroscopic analysis, surface imaging and depth profile analysis have shown that the amount of deposited copper species on the gold loop electrode was increased upon increasing electrode temperature during the deposition step. Therefore, the presence of chloride in the solution will hinder underpotential deposition of Cu(0) and lead to badly defined and resolved stripping peaks.