Copper underpotential deposition on TiO_2 electrodes: A voltammetric and electrochemical quartz crystal nanobalance study

摘要

In this work, the electrogravimetric behavior of copper electrodeposition on TiO_2 electrodes was analyzed. Copper electrodeposition was carried out in 0.1 mol L~(-1) H_2SO_4 using several concentrations of CuSO_4. 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 CuSO_4 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 TiO_2 film.