Different electrochemical techniques for the electrosynthesis of poly methylene blue in sodium saccharin aqueous medium

The present work describes the electropolymerization of methylene blue (MB) on transparent fluorine-doped tin oxide (FTO) from an aqueous solution of sodium saccharin. Compact, homogeneous, and adherent films are successfully achieved on FTO by different electrochemical techniques such as cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP). Scanning electron microscopy (SEM) shows that the obtained PMB films are thin and smooth. Raman spectroscopy and X-ray photo-electron spectroscopy (XPS) techniques were used to confirm the chemical composition of poly methylene blue (PMB) deposited on FTO and doped by saccharin counter ions. Optical characterization of PMB was achieved by UV-visible spectroscopy. The PMB presents an absorption in the visible range with an optical band gap of around 1.59 eV, which represents the conduction band and makes the system interesting for photovoltaic applications.