Unraveling distinct effects between CuO x and PtCu alloy sites in Pt-Cu bimetallic catalysts for CO oxidation at different temperatures.

In situ exploration of the dynamic structure evolution of catalysts plays a key role in revealing reaction mechanisms and designing efficient catalysts. In this work, PtCu/MgO catalysts, synthesized via the co-impregnation method, outperforms monometallic Pt/MgO and Cu/MgO. Utilizing quasi/in-situ characterization techniques, it is discovered that there is an obvious structural evolution over PtCu/MgO from Pt x Cu y O z oxide cluster to PtCu alloy with surface CuO x species under different redox and CO oxidation reaction conditions. The synergistic effect between PtCu alloy and CuO x species enables good CO oxidation activity through the regulation of CO adsorption and O 2 dissociation. At low temperatures, CO oxidation is predominantly catalyzed by surface CuO x species via the Mars-van Krevelen mechanism, in which CuO x can provide abundant active oxygen species. As the reaction temperature increases, both surface CuO x species and PtCu alloy collaborate to activate gaseous oxygen, facilitating CO oxidation mainly through the Langmuir-Hinshelwood mechanism.