Preparation and electrochemical nanogravimetric study on the ruthenium(III) trichloride-polypyrrole nanocomposite

Abstract

Nanocomposites were prepared by in situ redox intercalative polymerization method, in which α-RuCl 3 microcrystals were soaked in pyrrole. Polypyrrole (PP) was formed as a result of the intercalation of pyrrole into the layered structure of RuCl 3 crystal and the reaction between pyrrole and the host material. The appearance of polypyrrole was proven by infrared spectroscopy. The as-formed (PP) z+ (RuCl 3) z− nanocomposites were attached to paraffin-impregnated graphite or gold surfaces and studied by cyclic voltammetry and electrochemical nanogravimetry. The redox behaviour of the composite shows the electrochemical transformations of both the polypyrrole and RuCl 3. The redox waves of PP are similar to those observed for very thin PP films. It attests that the response is originated from monolayer-like PP film situated between RuCl 3 layers. The transport of the charge-compensating ions reflects the variation of the oxidation states of both PP and RuCl 3. The nanocomposites behave as self-doped layers in the potential region when both constituents are charged, i.e., PP is partially oxidized while RuCl 3 is partially reduced, since the electroneutrality is assured by mutual charge compensation. When PP is reduced, cations enter the layer to counterbalance the negative charge resulted from the reduction of Ru(III) to Ru(II). It was also found that the intercalation of water molecules is – albeit still substantial – smaller than that of pure RuCl 3 microcrystals which is related to the presence of PP between the RuCl 3 layers.