Abstract
Supports are commonly implemented in the industrial application of heterogeneous catalysts to improve the stability and recyclability of catalysts. The supported catalysts often show the enhanced activity and selectivity in various catalytic reactions. However, the specific contributions of electronic and steric effects to a catalytic system often remain elusive due to the lack of well-defined model systems. In this work, two types of uniform Pd nanocrystals covered by {111} facets in tetrahedral and octahedral shapes, respectively, are synthesized with identical chemical environment and loaded on TiO2 supports to form hybrid structures (Pd{111}-TiO2) towards the application of formic acid decomposition. Our observation suggests that the polarization effect at the interface of Pd-TiO2 enhances its activity in formic acid decomposition. Moreover, the Pd tetrahedrons-TiO2 hybrid structure whose Pd{111}-TiO2 interface possesses a larger angle shows higher catalytic activity, owing to the reduced steric effect as compared to Pd octahedrons-TiO2. This study reveals the nature of interface effects in formic acid decomposition, and provides a guidance for the related catalyst design.