σigma high resolution scanning electron microscope

Field Emission Scanning Electron Microscopy (FE-SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) was performed with a ΣIGMA high-resolution scanning electron microscope (Carl Zeiss Microscopy GmbH, Germany). The electrodes' morphological characterization was assessed on the uncoated working electrode surface, using an acceleration potential of 2 kV at a working distance of about 4 mm. Energy-dispersive X-ray analysis (EDX) was performed using a silicon drift detector (Oxford Instruments) coupled with SEM using a working distance of about 8.5 mm and an accelerating potential of 15 kV, analyzing a sampling area ranging from 0.06 to 0.09 mm 2 .

Cyclic Voltammetry (CV), Differential Pulse Voltammetry (DPV), and Electrochemical Impedance Spectroscopy (EIS) measures were performed by using a portable Palmsens 4 Potentiostat/Galvanostat/Impedance Analyzer (Palm Instruments BV, Houten, Netherlands) equipped with PS trace software. Screen-printed electrodes (SPE) with a threeelectrode configuration (working and counter electrode of graphite, and silver as pseudo-reference electrode) from EcoBioServices (Florence, Italy) were used. Absorbance measurements were obtained using a JENWAY 6400 Spectrophotometer from Barloworld Scientific (Staffordshire, UK). Scanning electron microscopy (SEM) and energydispersive X-ray spectroscopy (EDX) was performed with a ΣIGMA high-resolution scanning electron microscope (Carl Zeiss Microscopy GmbH, Germany).