Facet-Dependent Catalytic Activities of Au Nanoparticles Enclosed by High-Index Facets

We employed surface-enhanced Raman scattering as a noninvasive in situ spectroscopic tool to quantitatively study the intrinsic facet-dependent catalytic activities of colloidal subwavelength Au nanoparticles enclosed by various types of well-defined high-index facets using the catalytic hydrogenation of 4-nitrothiophenol as a model reaction. Our results provide compelling experimental evidence on the crucial roles of undercoordinated surface atoms in Au-based heterogeneous catalysis and shed light on the underlying relationship between the atomic-level surface structures and the intrinsic catalytic activities of Au nanocatalysts.