Pd Nanocrystals with Continuously Tunable High-Index Facets as a Model Nanocatalyst

Knowledge of the structure-reactivity relationship of catalysts is usually gained through using well-defined bulk single-crystal planes as model catalysts. However, there exists a huge gap between bulk single-crystal planes and practical nanocatalysts in terms of size, structural complexity, and local environment. Herein, we efficiently bridged this gap by developing a model nanocatalyst based on nanocrystals with continuously tunable surface structures. Pd nanocrystals with finely tunable facets, ranging from a flat {100} low-index facet to a series of {hk0} high-index facets, were prepared by an electrochemical square-wave potential method. The validity of the Pd model nanocatalyst has been demonstrated by structure-reactivity studies of electrocatalytic oxidation of small organic molecules. We further observed that Pd nanocrystals exhibited catalytic performance considerably different from bulk Pd single-crystal planes with the same Miller indices. Such differences were attributed to special catalytic functions conferred by nanocrystal edges. This study paves a promising route for investigating catalytic reactions effectively at the atomic level and nanoscales.