Crystal-Plane-Controlled Selectivity of Cu2O Catalysts in Propylene Oxidation with Molecular Oxygen

The selective oxidation of propylene with O-2 to propylene oxide and acrolein is of great interest and importance. We report the crystal-plane-controlled selectivity of uniform capping-ligand-free Cu2O octahedra, cubes, and rhombic dodecahedra in catalyzing propylene oxidation with O-2: Cu2O octahedra exposing {111} crystal planes are most selective for acrolein; Cu2O cubes exposing {100} crystal planes are most selective for CO2; Cu2O rhombic dodecahedra exposing {110} crystal planes are most selective for propylene oxide. One-coordinated Cu on Cu2O(111), three-coordinated O on Cu2O(110), and two-coordinated O on Cu2O(100) were identified as the catalytically active sites for the production of acrolein, propylene oxide, and CO2, respectively. These results reveal that crystal-plane engineering of oxide catalysts could be a useful strategy for developing selective catalysts and for gaining fundamental understanding of complex heterogeneous catalytic reactions at the molecular level.