Resolving the puzzle of single-atom silver dispersion on nanosized γ-Al(2)O(3) surface for high catalytic performance

Ag/γ-Al(2)O(3) is widely used for catalyzing various reactions, and its performance depends on the valence state, morphology and dispersion of Ag species. However, detailed anchoring mechanism of Ag species on γ-Al(2)O(3) remains largely unknown. Herein, we reveal that the terminal hydroxyls on γ-Al(2)O(3) are responsible for anchoring Ag species. The abundant terminal hydroxyls existed on nanosized γ-Al(2)O(3) can lead to single-atom silver dispersion, thereby resulting in markedly enhanced performance than the Ag cluster on microsized γ-Al(2)O(3). Density-functional-theory calculations confirm that Ag atom is mainly anchored by the terminal hydroxyls on (100) surface, forming a staple-like local structure with each Ag atom bonded with two or three terminal hydroxyls. Our finding resolves the puzzle on why the single-atom silver dispersion can be spontaneously achieved only on nanosized γ-Al(2)O(3), but not on microsized γ-Al(2)O(3). The obtained insight into the Ag species dispersion will benefit future design of more efficient supported Ag catalysts.