Sol-gel synthesis and XPS study of vanadium-hydroquinone oxide bronze films

A vanadium – hydroquinone oxide bronze has been synthesized by using a sol gel technology. The V2O5 powder, hydrogen peroxide, and hydroquinone C6H4(OH)2 were used as the starting materials to produce the bronze. At first the vanadium gel was made by the dissolving of vanadium pentoxide powder in hydrogen peroxide at 273 K. Then the solution was heated up to 350 K for the dissociation of peroxide complexes. An aqueous solution of hydroquinone was mixed with the formed gel in molar ratio 0.33:1. In this way the V2O5±δ·nH2O/HQ (HQ-hydroquinone) gel was synthesized. These gels are applied on the Ni pad and dried in an air (wet gel synthesis) or heated up to 580 K in air for 1 h for the water removal from gel (bronze production). The wet gel, as well as a bronze, was investigated by means of XPS method. Analysis of V-O region of XPS spectra shows that vanadium in both cases (wet gel and bronze) is in stable V5+ state. Oxygen in wet gel can be associated with V ions, hydroxide group and water. In bronze oxygen is connected with V and hydrogen (hydroxide). (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)