Catalytic properties of trivalent rare-earth oxides with intrinsic surface oxygen vacancy.

Oxygen vacancy (O v ) is an anionic defect widely existed in metal oxide lattice, as exemplified by CeO 2 , TiO 2 , and ZnO. As O v can modify the band structure of solid, it improves the physicochemical properties such as the semiconducting performance and catalytic behaviours. We report here a new type of O v as an intrinsic part of a perfect crystalline surface. Such non-defect O v stems from the irregular hexagonal sawtooth-shaped structure in the (111) plane of trivalent rare earth oxides (RE 2 O 3 ). The materials with such intrinsic O v structure exhibit excellent performance in ammonia decomposition reaction with surface Ru active sites. Extremely high H 2 formation rate has been achieved at ~1 wt% of Ru loading over Sm 2 O 3 , Y 2 O 3 and Gd 2 O 3 surface, which is 1.5-20 times higher than reported values in the literature. The discovery of intrinsic O v suggests great potentials of applying RE oxides in heterogeneous catalysis and surface chemistry.