The electrochemical polymerization of methylene blue and properties of polymethylene blue

The electrochemical polymerization of methylene blue in the aqueous solutio ns has been carried out using repeated potential cycling. The scan potentia l was controlled at the region of -0.40 and 1.10 V, and the region of -0.40 and 0.92 V (vs. saturated calomel electrode, SCE). A blue film, i.e., poly methylene blue was formed on the platinum foil, and had a good electrochemi cal activity and reversibility in the pH region of 2.0 and 8.0. There are a n anodic peak and a cathodic peak on the cyclic voltammograms. The currents of both anodic and cathodic peaks are proportional to upsilon(1/2) at the scan rate (upsilon) region of 25 and 600 mV s(-1). The electrochemical prop erty of polymethylene blue polymerized on the platinum foil is different fr om that polymerized on the glassy carbon electrode. The visible spectra of polymethylene blue indicate that the wavelengths of absorption peaks are in dependent of potential at the range between 0.50 and -0.30 V (vs. Ag/AgCl w ith saturated KCl solution) and change a little with pH at the range betwee n 3.0 and 8.0. The W-Visible spectra and Raman spectra of polymethylene blu e are different from those of methylene blue. (C) 1999 Elsevier Science S.A . All rights reserved.