Stabilization of catalytically active Cu+ surface sites on titanium-copper mixed-oxide films

Abstract

The oxidation of CO is the archetypal heterogeneous catalytic reaction and plays a central role in the advancement of fundamental studies, the control of automobile emissions, and industrial oxidation reactions. Copper-based catalysts were the first catalysts that were reported to enable the oxidation of CO at room temperature, but a lack of stability at the elevated reaction temperatures that are used in automobile catalytic converters, in particular the loss of the most reactive Cu+ cations, leads to their deactivation. Using a combined experimental and theoretical approach, it is shown how the incorporation of titanium cations in a Cu2O film leads to the formation of a stable mixed-metal oxide with a Cu+ terminated surface that is highly active for CO oxidation. Positively active: Copper oxide based structures were the first that could catalyze the oxidation of CO at room temperature. Their deactivation, however, is facile, because the required Cu+ state cannot be preserved under the reaction conditions. The addition of the right amount of titanium leads to mixed CuTiOx films that are thermally and chemically stable and more active CO oxidation catalysts than pure copper oxide materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.