Electrocatalytic oxidation and detection of hydrazine at conducting polymer/lignosulfonate composite modified electrodes

Abstract

Polypyrrole/lignosulfonate (PPy/LS) and PEDOT/lignosulfonate (PEDOT/LS) composites were electrogenerated on a glassy carbon electrode by galvanostatic polymerization. Cyclic voltammograms of the thus obtained composite thin films in neutral buffer solution exhibited well–defined redox couples originating from the quinone/hydroquinone couple in lignosulfonate. The combination of conducting polymers and lignosulfonate produces materials showing remarkable electrocatalytic activity toward the oxidation of hydrazine. At such electrodes the electroxidation of hydrazine occurs at a potential of ca. 0.2V vs. Ag/AgCl, where oxidation is not possible at PEDOT and PPy doped with ClO4− anions. Voltammetric data showed that the electrooxidation of hydrazine was a pure diffusion-controlled reaction and the total number of electrons involved in oxidation of hydrazine was equal to 4. Moreover, the catalytic rate constants (kcat) were estimated using chronoamperometry and found to be 2.6·104 and 6.8·104M−1s−1 for GCE/PPy/LS and GCE/PEDOT/LS, respectively. Amperometric sensitivity values for PPy/LS and PEDOT/LS films at optimal thickness were determined to be 285μAmM−1cm−2 and 137μAmM−1cm−2, respectively.