Understanding the Roles of Thiophenol-Ligated Ag-Based Nanoclusters on TiO2 during the Catalytic Hydrogenation of
Xiaofei Huang1,2, Yutong Xiao1,3, Yulin Li1,2
1Key Laboratory of Green Chemical Process of Ministry of Education, Wuhan Institute of Technology, Wuhan 430205, China.
Abstract:
Elucidating the correlations between the core structure of atomically precise nanoclusters and their catalytic activities is fundamentalfor exploring highly efficient nanocatalysts. Herein, a series of Ag-based nanoclusters protected by 2,4-dimethylphenylthiophenol (specifically Ag4Pd2(SPhMe2)8 and Ag24M(SPhMe2)18 where M = Ag, Pd, and Pt) were synthesized and deposited on TiO2 supports as heterogeneous catalysts for the selective hydrogenation of nitroarenes with NaBH4 as the reductant. It was found that Ag4Pd2(SPhMe2)8 could spontaneously lose its ligands during catalysis, leading to the formation of polydispersed AgPd nanoparticles. This transformation endows the system with extraordinary activity for driving the hydrogenation of nitroarenes. However, the Ag24M (M = Ag, Pd, and Pt) systems, maintain their core structures during catalysis. They follow the generally reported ligand-mediated hydride-involved process, with catalytic activities depending on the central atom (Pt > Pd > Ag), which affects the hydride transferred from the nanoclusters to the reactant to regulate the catalysis.
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