**2.2 EQCM measurements**

EQCM measurements were conducted using a PAR 273A (Princeton Applied Research) potentiostat-galvanostat coupled to an electrochemical quartz crystal microbalance Seiko model QCA922, both controlled by WinEchem V. 1.5 installed in a personal computer. The quartz crystal resonator was mounted in a home-made acrylic cell (Figure 2). This cell is characterized by the commercial holder of quartz and it is united to made in home solution container, so the sample container also hold the quartz crystal. As the sample container is acrylic only aqueous solutions can be used with this cell.

Fig. 2. Photograph of A) diassembled and B) assembled cell: (a) acrylic sample container, (b) acrylic cell cover, (c) teflon quartz crystal and his container, (d) O-rings, (e) acrylic cover of quartz cristal container, (f) teflon cover of quartz crista container and (g) coin (φ = 0.8 cm).
