Electrochemical study of glassy carbon electrodes modified with zirconium phosphate and some azine-type redox dyes

Glassy carbon (GC) electrodes were modified with a layer of zirconium phosphate (ZrP), using either direct chemical synthesis onto the surface or a ZrP gel droplet evaporation procedure. The azine-type dyes nile blue A (NB) and toluidine blue O (TB) were immobilized onto the ZrP-modified GC electrodes either by adsorption onto just the formed layer of ZrP or by inclusion into the ZrP matrix during its chemical synthesis. The electrochemical behavior of the GC . Zr . Pdye composite electrodes was studied. For GC . ZrP-modified electrodes prepared by chemical synthesis on the surface, coverage by NE or TB of one or a few monolayers was found, with E,values for these redox couples slightly shifting by ca. 0.05 V to the negative direction. For the GC . ZrP electrodes prepared by gel droplet evaporation, the E-m values for NE and TB appear initially shifted by ca. 0.2 V to the positive direction; however, both cathodic and anodic peaks return to their usual positions on the potential scale during soaking these electrodes in a buffer solution.