Spillover of primary oxides as a dynamic catalytic effect of interactive hypo-d-oxide supports

The aim of the present paper is to introduce electron conductive and d-d-interactive individual and composite hypo-d-oxides of increased altervalent capacity, or their suboxides (Magneli phases), as catalytic supports and therefrom provide: (i) the Strong Metal-Supports Interaction (SMSI) effect and (ii) dynamic spillover interactive transfer of primary oxides (M-OH) for further electrode reactions and thereby advance the overall electrocatalytic activity. Since hypo-d-oxides feature the exchange membrane properties, the higher the altervalent capacity, the higher the spillover effect. This is the reason why anatase titania has now been doped with a certain amount of colloidal tungstenia (WO3) ingredient, and the latter individually employed as the interactive catalyst support. Potentiodynamic experiments have shown that the reversible peak of the primary oxide growth on Pt, Ru and Au supported upon hypo-d-oxides and suboxides becomes distinctly increased in the charge capacity and shifted to remarkably more negative potential values, so that it starts even within the range of H-adatoms desorption, while its reduction extends until and merge with the UPD of hydrogen atoms. With wet tungstenia-doped titania-supported Pt catalyst in membrane cells, these peaks dramatically increase in their charge capacity and reversibly become shrunk with decreased moisture content in the feeding inert gas mixture, and vice versa. Such distinct potentiodynamic scans in conjunction with some broadened complementary kinetic electrocatalytic improvements, rising from the same hypo-d-oxide and/or suboxide interactive support effects, have been proved to be the best and comparable experimental evidence for the spillover effect of primary oxides. (c) 2007 Elsevier Ltd. All rights reserved.