An Atomic‐Level Strategy for Unraveling Gold Nanocatalysis from the Perspective of Aun(SR)m Nanoclusters

An atomic‐level strategy is devised to gain insight into the origin of nanogold catalysis by using atomically monodisperse Au_n(SR)_m nanoclusters as well‐defined catalysts for styrene oxidation. The Au_n(SR)_m nanoclusters are emerging as a new class of gold nanocatalyst to overcome the polydispersity of conventional nanoparticle catalysts. The unique atom‐packing structure and electronic properties of Au_n(SR)_m nanoclusters (<2 nm) are rationalized to be responsible for their extraordinary catalytic activity observed in styrene oxidation. An interesting finding is that quantum size effects of Au_n(SR)_m nanoclusters, rather than the higher specific surface area, play a major role in gold‐catalyzed selective oxidation of styrene. For example, Au₂₅(SR)₁₈ nanoclusters (≈1 nm) are found to be particularly efficient in activating O₂, which is a key step in styrene oxidation, and hence, the ultrasmall Au₂₅ catalyst exhibits higher activity than do larger sizes. This atomic‐level strategy has allowed us to obtain an important insight into some fundamental aspects of nanogold catalysis in styrene oxidation. The ultrasmall yet robust Au_n(SR)_m nanoclusters are particularly promising for studying the mechanistic aspects of nanogold catalysis and for future design of better catalysts with high activity and selectivity for certain chemical processes.