Characterization and electrocatalytic application of silver modified polypyrrole electrodes

Abstract

Silvermodified polypyrrole electrodes were prepared with the aim of testing them for the electro oxidation of formaldehyde in alkaline solution. The modification of polypyrrole by immersion in aqueous AgNO3 solution was studied by cyclic voltammeter and vacuum techniques (AES and XPS). The influence of time of immersion and the thickness of the polypyrrole film, prepared by electrochemical polymerization, on the modification of the polymer were examined. The results acquired from both electrochemical and spectroscopic examinations show that immersion of a polypyrrole electrode in a AgNO3 solution results in its modification with silver, which is deposited in the elemental state on the surface. The quantity of silver deposited depends not only on the immersion time but also on the thickness of the polymer film. A modified PPy/Ag electrode exhibits catalytic activity for the electro oxidation of CH2O in NaOH. In spite of the low quantity of silver, the activity of the electrode for this reaction is comparable to that of a polycrystalline silver electrode.

Elektrode od polipirola modifikovanog srebrom (PPy/Ag) ispitivane su za elektrooksidaciju formaldehida u natrijum-hidroksidu. Polipirol je modifikovan samo uranjanjem u rastvor srebro-nitrata, a dobijene elektrode su ispitivane cikličnom voltametrijom i vakuum tehnikama (AES i XPS). Polipirol je dobijen elektrohemijskom polimerizacijom pirola, a ispitivan je uticaj vremena uranjanja i debljine polimernog filma na modifikaciju polimera srebrom. Rezultati dobijeni elektrohemijskim i spektroskopskim ispitivanjima su pokazali da se polipirol uronjen u rastvor srebro-nitrata spontano modifikuje srebrom koje se taloži u elementarnom obliku. Količina nataloženog srebra zavisi ne samo od vremena uranjanja već i od debljine polimernog filma. Modifikovane elektrode PPy/Ag pokazuju katalitičku aktivnost za elektrooksidaciju formaldehida u natrijum-hidroksidu. Aktivnost ovih elektroda i pri malim količinama spontano nataloženog srebra, uporediva je sa aktivnošću polikristalne srebrne elektrode.