Unraveling distinct effects between CuO 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 PtCuO oxide cluster to PtCu alloy with surface CuO species under different redox and CO oxidation reaction conditions. The synergistic effect between PtCu alloy and CuO species enables good CO oxidation activity through the regulation of CO adsorption and O dissociation. At low temperatures, CO oxidation is predominantly catalyzed by surface CuO species via the Mars-van Krevelen mechanism, in which CuO can provide abundant active oxygen species. As the reaction temperature increases, both surface CuO species and PtCu alloy collaborate to activate gaseous oxygen, facilitating CO oxidation mainly through the Langmuir-Hinshelwood mechanism.