Unique size-dependent nanocatalysis revealed at the single atomically precise gold cluster level

Abstract

Atomically precise metal clusters have attracted increasing interest owing to their unique size-dependent properties; however, little has been known about the effect of size on the catalytic properties of metal clusters at the single-cluster level. Here, by real-time monitoring with single-molecule fluorescence microscopy the size-dependent catalytic process of individual Au clusters at single-turnover resolution, we study the size-dependent catalytic behaviors of gold (Au) clusters at the single-cluster level, and then observe the strong size effect on the catalytic properties of individual Au clusters, in both catalytic product formation and dissociation processes. Surprisingly, indicated by both experiments and density functional theory (DFT) calculations, due to such a unique size effect, besides observing the different product dissociation behaviors on different-sized Au clusters, we also observe that small Au clusters [i.e., Au15(MPA)13; here, MPA denotes 3-mercaptopropionic acid] catalyze the product formation through a competitive Langmuir–Hinshelwood mechanism, while those relatively larger Au clusters [e.g., Au18(MPA)14 and Au25(MPA)18] or nanoparticles catalyze the same process through a noncompetitive Langmuir–Hinshelwood mechanism. Such a size effect on the nanocatalysis could be attributed intrinsically to the size-dependent electronic structure of Au clusters. Further analysis of dynamic activity fluctuation of Au clusters reveals more different catalytic properties between Au clusters and traditional Au nanoparticles due to their different size-dependent structures.

Reaction mechanisms at the homogeneous–heterogeneous frontier: insights from first-principles studies on ligand-decorated metal nanoparticles

“…They initially serve as capping agents to limit the growth and maintain welldispersed small-size metal NPs and can modify shapes themselves, 9,10 which in turn impacts their catalytic performance. [11][12][13] More importantly, such a ligand-metal interface is actually quite dynamic and can potentially (i) open or block catalytic sites on the surface, (ii) alter the exposed metal surface, (iii) change the electronic structure of the metal, (iv) impose stereo-electronic effects on reactants and products, and (v) tune properties on the metal/ligand/solvent boundaries. 14 By analogy with the sergeants-and-soldiers principle, 15,16 its role may be described as a cooperative action of small individuals that contributes to amplify a certain chemical property, such as activity, selectivity, or stability.…”

Small Size Effect and Concentration Response of Gold Nanoparticles in Electrochemiluminescence Reaction

“…Unique chemical properties of AuNPs also include easy to functionalize and immobilize on the surface of the media [5][6][7]. Therefore, AuNPs-based small size effect offer broad special capabilities with multiple applications [8,9]. Especially, AuNPs are often used as a carrier and a marker in detection of ions [10], small molecules [11], proteins [12], DNA [13] and cancerous cells [14], due to their combination with a variety of biological macromolecules.…”

A General Method for Structure Prediction of Metal-Ligand Interfaces of Hybrid Nanoparticles

“…Hybrid metal nanoparticles, consisting of a nano-crystalline metal core and a protecting layer (shell) of organic ligand molecules, have applications in diverse areas such as biolabeling, catalysis, nanomedicine and solar energy. [1][2][3][4][5][6][7][8] The core-shell framework structure of hybrid nanoparticles offers ample opportunities to tune the physico-chemical properties and functionalities of the particles via controlling the size, shape, elemental composition, and structure of the metal core, together with the chemical composition of the ligand shell. The chemical interactions between the metal atoms and ligand molecules at the core-shell interface are in a crucial role since they dictate the atomic-scale structure, stability, and ensuing properties of the particle.…”