Electrosynthesized iridium oxide-polymer nanocomposite thin films for electrocatalytic oxidation of arsenic(III)

Nanocomposite materials have been synthesized by electrodeposition of iridium oxide nanoparticles into poly(pyrrole-alkylammonium) films coated by oxidative electropolymerization of a pyrrole-alkylammonium monomer onto carbon electrodes, and characterized by electrochemistry in aqueous electrolytes and by transmission electron microscopy. Iridium oxide-based nanocomposite electrode materials appeared efficient electrocatalysts for the oxidation of arsenic(III) into arsenic(V) species at low potentials, i.e. in the 0.3-0.7 V vs. Ag/AgCl range, and over a large pH range. Bulk electrocatalytic oxidation of arsenite solutions could be performed in the presence of a water-soluble poly(quaternary ammonium) salt acting as the supporting electrolyte and also as an As(V) complexing agent, which allowed the combination of electrocatalytic oxidation of As(III) with the liquid phase polymer-assisted retention (LPR) technique to efficiently remove arsenic from polluted solutions.