Crystal‐Plane‐Controlled Surface Chemistry and Catalytic Performance of Surfactant‐Free Cu2O Nanocrystals

Abstract Surfactant‐free Cu 2 O nanocrystals, including cubes exposing {100} crystal planes, octahedra exposing {111} crystal planes, and rhombic dodecahedra exposing {110} crystal planes, were used as model catalysts to study the effect of the crystal plane on the surface chemistry and catalytic performance for CO oxidation of Cu 2 O nanocrystals. The catalytic performance follows the order of octahedra≫rhombic dodecahedra>cubes; this suggests that Cu 2 O(111) is most active in catalyzing CO oxidation among Cu 2 O (111), (110), and (100) surfaces. CO temperature‐programmed reduction results demonstrate that Cu 2 O octahedra are the most easily reduced of the Cu 2 O cubes, octahedra, and rhombic dodecahedra. Diffuse reflectance FTIR spectra show that CO chemisorption on Cu 2 O nanocrystals depends on their shape and the chemisorption temperature. CO chemisorption is strongest on rhombic dodecahedra at 30 °C, but at 150 °C on octahedra. Both the reducibility and chemisorption ability of various Cu 2 O nanocrystals toward CO are consistent with their catalytic performance in CO oxidation. The observed surface chemistry and catalytic performance in CO oxidation of various Cu 2 O nanocrystals can be well correlated with their exposed crystal plane and surface composition/structure. Cu 2 O octahedra expose the {111} crystal plane with coordinated, unsaturated Cu I sites, and thus, are most active in chemisorbing CO and catalyzing CO oxidation. These results nicely demonstrate the crystal‐plane‐controlled surface chemistry and catalytic performance of oxide catalysts.