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

This paper reports a novel two-step one-pot all-electrochemical method for the preparation of interpenetrating conducting-polymer (polyaniline, PANI) semiconducting oxide (V 2 O 5 ) 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 V 2 O 5 component which is also deposited electrochemically. The dimensionality of the amorphous V 2 O 5 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 V 2 O 5 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/cm 2, the 51 V solid-state NMR spectrum of the V 2 O 5 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 51 V nuclear spin. The magnitude of this 51 V Knight shift is unprecedented exceeding by a significant margin any of those previously reported for vanadium oxide compounds.