Copper underpotential deposition on TiO2 electrodes: A voltammetric and electrochemical quartz crystal nanobalance study

In this work, the electrogravimetric behavior of copper electrodeposition on TiO2 electrodes was analyzed. Copper electrodeposition was carried out in 0.1 mol L-1 H2SO4 using several concentrations of CuSO4. The voltammetric curve displays a redox processes. The first redox process occurs in the region of -0.30 at 0.1 V (vs. saturated calomel electrode, SCE) and it is related to bulk Cu electrodeposition and stripping. For this cathodic process, it was observed that the mass gain increases both as the sweep rate decreases and as the concentration of copper increases. The second redox process, which occurs between -0.1 V and 0.35 V (vs. SCE), the stripping charge (and mass) are independent of both sweep rate and CuSO4 concentration and, finally, there is a saturation charge (and saturation mass) as the deposition time is increased. From the saturated mass, obtained using an electrochemical quartz crystal nanobalance, for this electrodeposition process (248 ng cm(-2)) a roughness factor of 1.8 was calculated for the TiO2 film. (C) 2009 Elsevier B.V. All rights reserved.