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

The selective oxidation of propylene with O2 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 O2: 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. Just plane favoritism: In the catalysis of propylene oxidation with O2 to acrolein, propylene oxide, and CO2, Cu2O octahedra with exposed {111} crystal planes favored the formation of acrolein, Cu2O cubes with exposed {100} crystal planes gave CO2 preferentially, and Cu2O rhombic dodecahedra with exposed {110} crystal planes gave a higher proportion of propylene oxide. The active sites for these reactions were identified as indicated in the scheme.