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

Abstract

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.

The tetrahedral structure and luminescence properties of Bi-metallic Pt1Ag28(SR)18(PPh3)4 nanocluster

“…11,20a,21b,22–26 The synthetic methods used to prepare bimetallic NCs can be roughly classified into two strategies: (1) the co-reduction of two metal precursors ( e.g. complexes) in one-pot reactions 7,11,20,21b,22b,24 and (2) doping mono-metallic NCs (which serve as templates) with heteroatom complexes. 25a,29–32 For the synthesis of mono-metallic NCs, the thiol etching-induced transformation method is commonly used, 19,33 which gives rise to NCs with novel structures and distinct properties.…”

Engineering Surface Ligands of Noble Metal Nanocatalysts in Tuning the Product Selectivity

“…The surface ligands are demonstrated to be detrimental to the catalytic activity in many examples [20][21][22][23][24][25][26][27]. The formation of SAMs is often considered to block the surface accessibility, leading to a decrease in the accessibility of catalytic sites [20,23], although there are many reported examples showing that surface ligands do not depress catalytic activity of metal NPs [28][29][30][31]. This will not be our focus but will be briefly discussed in the outlook.…”

On-demand Hydrogen Production from Organosilanes at Ambient Temperature Using Heterogeneous Gold Catalysts

“…In addition, the use of heterogeneous catalysts should allow easy separation from organosilane, leading to on/off-switching of H 2 -production. Several heterogeneous catalysts for the hydrolytic oxidation of organosilanes have been reported28293031323334353637. However, these catalysts were developed for the synthesis of organosilanols, and no attention has been paid for the utilization of heterogeneous catalysts for H 2 -production through hydrolytic oxidation of inexpensive organosilanes such as PMHS and TMDS.…”