All electrochemical measurements were performed, at room temperature, on an USB-based portable electrochemical station m-Stat 100 potentiostat controlled by PSLite 1.6 software and on a carbon screen-printed electrode (CSPE), which integrates the three-electrode system, a carbon working electrode of 4mm diameter as well as a carbon counter and silver (Ag) pseudoreference electrodes (Dropsens, Oviedo, Spain).