Elucidating the Nature of the Cu(I) Active Site in CuO/TiO₂ for Excellent Low-Temperature CO Oxidation

Stabilized Cu⁺ species have been widely considered as catalytic active sites in composite copper catalysts for catalytic reactions with industrial importance. However, few examples comprehensively explicated the origin of stabilized Cu⁺ in a low-cost and widely investigated CuO/TiO₂ system. In this study, mass producible CuO/TiO₂ catalysts with interface-stabilized Cu⁺ were prepared, which showed excellent low-temperature CO oxidation activity. A thorough characterization and theoretical calculations proved that the strong charge-transfer effect and Ti-O-Cu hybridization in Ti-doped CuO(111) at the CuO/TiO₂ interface contributed to the formation and stabilization of Cu⁺ species. The CO molecule adsorbed on Cu⁺ and reacted directly with Ti doping-promoted active lattice oxygen via a Mars-van Krevelen mechanism, leading to the enhanced low-temperature activity.