Shape-Dependent Reducibility of Cuprous Oxide Nanocrystals

In this paper the reducibility of octahedral and cubic Cu 2 O nanocrystals that respectively expose the (111) and (100) crystal planes has been investigated both experimentally and theoretically. Reduced either by H 2 or CO, the reduction temperature of octahedral Cu 2 O nanocrystals is lower than that of cubic Cu 2 O nanocrystals by more than 120 °C, which provides the unambiguous experimental results that the Cu 2 O(111) crystal plane is much more facile to be reduced than the Cu 2 O(100) crystal plane. The DFT calculation results reveal that the different reducibilities of octahedral and cubic Cu 2 O nanocrystals arise from their different surface structures, in which the Cu 2 O(111) surface has coordination unsaturated Cu but the Cu 2 O(100) surface does not. The chemisorption and activation of CO and H 2 are stronger on the Cu 2 O(111) surface than on the Cu 2 O(100) surface. These results provide the convincing evidence for the shape-dependent surface reactivity of oxide nanocrystals.