Structural studies on mixed W–Ce–O nanocomposites by means of EXAFS spectroscopy

Cerium oxide based nanocomposite systems play an important role in oxidation reactions and could be used as advanced anodes for intermediate temperature solid oxide fuel cells (SOFC). Cerium oxide is a major component in the three-way catalysts (TWC) used for the treatment of automotive exhaust gases [1]. The oxygen storage capacity associated with a fast Ce(IV)/Ce(III) redox process, is one of the key properties of this material [2]. Appropriate preparation procedures allow one to deposit nano-sized oxide particles on an active metal support, thus taking advantage of the reactivity of deposited nanoclusters and also the active metal support [3]. The mixed W–Ce–O nanocomposites in different compositions with varying atomic percentages of different elements, were prepared by wet impregnation of CeO2 powder with an aqueous solution containing increasing quantity of (NH4)6(W12O39)·H2O and calcined at 500oC in air. The significant differences in the activity of WO3 and CeO2 make the investigations on WO3 supported on CeO2 interesting and vital insights could be obtained by studying the influence of the supported oxide (WO3) on the surface reactivity of the support (CeO2). In one of our earlier works on Fe2O3 supported on mixed La–Sr–Co–Fe–O oxide, the investigations revealed the diffusion of Fe2O3 into the support leading to the formation of different oxide-based compounds [4]. Therefore, it i