Atomically Precise Alkynyl-Protected Metal Nanoclusters as a Model Catalyst: Observation of Promoting Effect of Surface Ligands on Catalysis by Metal Nanoparticles

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• 作者：Yu Wang ; Xian-Kai Wan ; Liting Ren ; Haifeng Su ; Gang Li ; Sami Malola ; Shuichao Lin ; Zichao Tang ; Hannu Häkkinen ; Boon K Teo ; Quan-Ming Wang ; Nanfeng Zheng
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：March 16, 2016
• 年：2016
• 卷：138
• 期：10
• 页码：3278-3281
• 全文大小：313K
• ISSN：1520-5126

文摘

Metal nanoclusters whose surface ligands are removable while keeping their metal framework structures intact are an ideal system for investigating the influence of surface ligands on catalysis of metal nanoparticles. We report in this work an intermetallic nanocluster containing 62 metal atoms, Au₃₄Ag₂₈(PhC≡C)₃₄, and its use as a model catalyst to explore the importance of surface ligands in promoting catalysis. As revealed by single-crystal diffraction, the 62 metal atoms in the cluster are arranged as a four-concentric-shell Ag@Au₁₇@Ag₂₇@Au₁₇ structure. All phenylalkynyl (PA) ligands are linearly coordinated to the surface Au atoms with staple “PhC≡C–Au–C≡CPh” motif. Compared with reported thiolated metal nanoclusters, the surface PA ligands on Au₃₄Ag₂₈(PhC≡C)₃₄ are readily removed at relatively low temperatures, while the metal core remains intact. The clusters before and after removal of surface ligands are used as catalysts for the hydrolytic oxidation of organosilanes to silanols. It is, for the first time, demonstrated that the organic-capped metal nanoclusters work as active catalysts much better than those with surface ligands partially or completely removed.