Unraveling the Distinct Effects of CuOx and PtCu alloy Sites in Pt−Cu Bimetallic Catalysts for CO Oxidation at Different Temperature

Abstract

Abstract The crucial role of different active sites in various reactions has been realized, while the distinguishing contribution of various species at different reactive temperature range is still scarcely presented. In this work, PtCu/MgO catalysts were prepared by co-impregnation method, and displayed superior performance compared to the related monometallic Pt/MgO or Cu/MgO catalyst. With the aid of comprehensive characterization techniques, it was discovered that there was an obvious reconstruction of platinum-copper oxide cluster to PtCu alloy-CuOx interface under reductive and oxidized conditions. The synergistic effect between PtCu alloy and CuOx species enables a good CO oxidation activity. In situ DRIFTS/CO-TPR and isotope labeling experiments indicated that the CO oxidation can be motivated at ~ 50 °C on surface CuOx species through M-vK mechanism, in which CuOx can provide abundant active oxygen species. As the increase of reaction temperature, a moderate CO adsorption on PtCu alloy avoids CO toxicity on Pt site and guarantees enough sites for the activation of gases oxygen into active oxygen species to promote CO oxidation by L-H mechanism. This work provides new idea for designing bimetallic catalysts with high performance for the low temperature CO oxidation and related reactions.