Electrosynthesis of Macroporous Polyaniline−V2O5 Nanocomposites and Their Unusual Magnetic Properties

Abstract

This paper reports a novel two-step one-pot all-electrochemical method for the preparation of interpenetrating conducting-polymer (polyaniline, PANI) semiconducting oxide (V2O5) nanocomposites. In the method, a spongy interconnected PANI network is first deposited on a titanium metal substrate. The electrodeposited PANI network has pores on the order of a few micrometers and is used as a template for the V2O5 component which is also deposited electrochemically. The dimensionality of the amorphous V2O5 that forms can be controlled through control of the current density during the deposition, and this in turn reduces the porosity. As the current density increases and more V2O5 is deposited, Raman and X-ray photoelectron spectroscopy (XPS) indicate that the conductivity of the PANI decreases. Regardless of the current density used in the range 1−5 mA/cm2, the 51V solid-state NMR spectrum of the V2O5 component shows a major resonance at about −8500 ppm which is ascribed to a Knight shift due to interaction of the PANI conduction electrons with the 51V nuclear spin. The magnitude of this 51V Knight shift is unprecedented exceeding by a significant margin any of those previously reported for vanadium oxide compounds.