Hybrid materials utilizing polyelectrolyte-derivatized carbon nanotubes and vanadium-mixed addenda heteropolytungstate for efficient electrochemical charging and electrocatalysis

Abstract

Preparation and electrochemical behavior of new hybrid materials composed of multi-walled carbon nanotubes (CNTs) that were derivatized with poly(diallyldimethylammonium) chloride and modified with vanadium-mixed addenda Dawson-type heteropolytungstate, [P2W17VO 62]8-, is described here. These nanostructured composite systems exhibited fast dynamics of charge propagation. They were characterized by the transport (effectively diffusional) kinetic parameter of approximately 8 × 10-8 cm-2 s-1/2 and the specific capacitance parameter of 82 F g-1 (at the charging/discharging current of 200 mA g-1). The latter parameter for bare CNTs was found to be only 50 F g-1 under analogous conditions. These observations were based on the results of galvanostatic charging-discharging, cyclic voltammetric, and AC impedance spectroscopic measurements. The improved capacitance properties were attributed to the systems' pseudocapacitive features originating from the fast redox transitions of the [P2W 17VO62]8- polyanions. In addition to the fast redox conduction, the proposed organic-inorganic hybrid materials exhibited interesting electrocatalytic activity toward reduction of bromate in the broad concentration range (sensitivity, 0.24 mA cm-2 mmol-1 dm3). © 2013 The Author(s).