Understanding the Roles of Thiophenol-Ligated Ag-Based\nNanoclusters on TiO<sub>2</sub> during the Catalytic Hydrogenation\nof Nitroarenes

Elucidating\nthe correlations between the core structure of atomically\nprecise nanoclusters and their catalytic activities is fundamentalfor\nexploring highly efficient nanocatalysts. Herein, a series of Ag-based\nnanoclusters protected by 2,4-dimethylphenylthiophenol (specifically\nAg<sub>4</sub>Pd<sub>2</sub>(SPhMe<sub>2</sub>)<sub>8</sub> and Ag<sub>24</sub>M(SPhMe<sub>2</sub>)<sub>18</sub> where M = Ag, Pd, and Pt)\nwere synthesized and deposited on TiO<sub>2</sub> supports as heterogeneous\ncatalysts for the selective hydrogenation of nitroarenes with NaBH<sub>4</sub> as the reductant. It was found that Ag<sub>4</sub>Pd<sub>2</sub>(SPhMe<sub>2</sub>)<sub>8</sub> could spontaneously lose its\nligands during catalysis, leading to the formation of polydispersed\nAgPd nanoparticles. This transformation endows the system with extraordinary\nactivity for driving the hydrogenation of nitroarenes. However, the\nAg<sub>24</sub>M (M = Ag, Pd, and Pt) systems, maintain their core structures during catalysis.\nThey follow the generally reported ligand-mediated hydride-involved\nprocess, with catalytic activities depending on the central atom (Pt\n> Pd > Ag), which affects the hydride transferred from the nanoclusters\nto the reactant to regulate the catalysis.