Complexations of polyoligothiophenes films with transition metals, and their use for electrocatalysis of ascorbic acid

Chemically modified electrodes prepared by electropolymerization of oligothiophenes such as: 2,2’-bithiophene (BT), 2,2’-bithiophene-5-carboxylic acid (BTCA) and terthiophene aldehyde (TTCHO) on platinum (Pt) electrodes, in acetonitrile solution containing 0.1 M tetrabutylammonium perchlorate (TBAP) and 0.01 M of monomer, are characterized by cyclic volammetry (CV), and X-ray photoelectron spectroscopy (XPS) measurements. By immersing the prepared modified electrodes in transition metals (Cu2+, Co2+ and Ag+) solutions, the metal ions were complexed with films. The electrochemical response shows clearly, the presence of oxidation and reduction peaks corresponding to metallic couple redox. XPS technique reveal that the films complexed with metal ions and determine the mode of the connection with film’s atoms. The obtained polyoligothiophenes-metal modified electrodes exhibited good electrocatalytic properties towards ascorbic acid (AA) oxidation after their complexation with metallic ions. The electrocatalytic response was evaluated by cyclic voltammetry with regard to the film nature, the metallic ion nature, immersion time, ascorbic acid concentration, and other variables. The results reveal that the catalytic activity of Ag+ complexed with BTCA thin-film is the best toward AA oxidation and it can be detected a very low concentration (∼1 μM), of AA in a solution which can be utilized as an efficient electrochemical sensor.