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

Oxygen vacancy (O) is an anionic defect widely existed in metal oxide lattice, as exemplified by CeO, TiO, and ZnO. As O 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 as an intrinsic part of a perfect crystalline surface. Such non-defect O stems from the irregular hexagonal sawtooth-shaped structure in the (111) plane of trivalent rare earth oxides (REO). The materials with such intrinsic O structure exhibit excellent performance in ammonia decomposition reaction with surface Ru active sites. Extremely high H formation rate has been achieved at ~1 wt% of Ru loading over SmO, YO and GdO surface, which is 1.5-20 times higher than reported values in the literature. The discovery of intrinsic O suggests great potentials of applying RE oxides in heterogeneous catalysis and surface chemistry.