Interfacial structures and reactivities of CeO₂/Cu(1 1 1) catalyst with strong interfacial interaction and charge transfer

Interfacial interactions have been recognized as a crucial factor affecting interfacial structures and catalytic performance. Herein, the interfacial structures, interactions, and catalytic properties of CeO₂/Cu(1 1 1) composites including monolayer, bilayer and trilayer CeO₂(1 1 1) on Cu(1 1 1) substrate were comparatively studied by DFT + U calculations. Our results showed that the interfacial interaction between CeO₂(1 1 1) and Cu(1 1 1) substrate increased linearly with the increase of CeO₂(1 1 1) thickness. This trend was well rationalized by analyzing the strong interfacial interactions, which were mainly due to the strong O-Cu chemical bonds formed by the hybridization of O-2p orbitals and Cu-3d orbitals at the interface. Significant charge transfer from Cu(1 1 1) substrate to CeO₂(1 1 1) layer resulted in the charge accumulations of surface O-Ce-O layer in order of ML-CeO₂/Cu(1 1 1) (- 1.06 |e|) > BL-CeO₂/Cu(1 1 1) (- 0.40 |e|) > TL-CeO₂/Cu(1 1 1) (+ 0.36 |e|). The intrinsic activity was further identified by employing CO oxidation as model reaction, and followed the order of BL-CeO₂/Cu(1 1 1) > ML-CeO₂/Cu(1 1 1) > TL-CeO₂/Cu(1 1 1) > ML-CeO₂(1 1 1) > TL-CeO₂(1 1 1) > BL-CeO₂(1 1 1). The results showed that the strong interfacial interaction and charge transfer were key factors for the good stability and excellent catalytic activity of CeO₂/Cu catalyst. All these findings provided insights for the design and application of ceria-based catalysts.