Scalable and Precise Synthesis of Thiolated Au_10–12, Au₁₅, Au₁₈, and Au₂₅ Nanoclusters via pH Controlled CO Reduction

Abstract

Large-scale production of thiolated Au nanoclusters (NCs) of tunable sizes is pivotal to realizing their practical applications. Here, we present a simple one-pot synthesis method for gram-scale production of various discretesized Au NCs (Au 10−12 , Au 15 , Au 18 , and Au 25 ) protected by different thiol ligands. The key design in our method is to use a gaseous reducing agent, carbon monoxide (CO), to support a mild reaction environment for a slow and well-controlled growth of Au NCs. The pH of the reaction solution was further used to fine-tune the reduction kinetics for the NC growth, leading to the formation of various sized Au NCs. The monodispersity of our products was verified by a number of characterization techniques (e.g., UV−vis, electrospray ionization (ESI)-MS, and X-ray photoelectron spectroscopy (XPS)). NMR spectroscopy was also used to investigate the structure of as-synthesized thiolated Au NCs, which suggested that Au 18 (SG) 14 NCs adopt a core−shell structure with two binding modes of the thiol ligands. The synthetic strategy developed in this study produced three small thiolated Au NCs (Au 10−12 , Au 15 , and Au 18 ) in large quantities that are not available in the current NC synthesis due to the lack of direct and scalable synthetic protocols.

Au-Edged CuZnSe2Heterostructured Nanosheets with Enhanced Electrochemical Performance

“…With increasing reaction temperature, however, a gradual absorption decrease at 279 nm is observed, whereas the absorption at 310 nm increases ( Figure S9, Supporting Information). [39][40][41] This indicates that the high temperature facilitates the aggregation and fusion of smaller Au clusters into bigger ones. At the same time it can be seen that the direct absorption peak of CuSe at 432 nm also increases, which implies the deposition of Cu on the clusters at higher temperature by increasing the reactivity of the Cu sources.…”

“…Control experiment indicated that Au strongly aggregated in the absence of DT, whereas the CuZnSe 2 domains remained stable, proving the role of DT in stabilizing the Au domains and that of OLA in stabilizing CuZnSe 2 . [39][40][41] Moreover, DT can reduce Au 3+ under moderate heating, thus producing DT-stabilized Au clusters. Although DT is capable to reduce elemental Se in the presence of OLA, as the Au 3+ to Au 0 reduction potential is much higher than that of Se 0 to Se 2− this makes the reduction of Au 3+ by DT more competitive (Table S3, Supporting Information).…”

“…[43][44][45][46] However, the reduction of Se and the appearance of the CuZnSe 2 domains occurs later on in the process than the formation of the Au clusters, again due to the high reduction potential of Au 3+ to Au 0 . [39][40][41][43][44][45][46] Consequently, the formation of Au clusters must occur prior to that of the CuZnSe 2 nanosheets.…”

“…These clusters do not exhibit fl uorescence, which are different from the previously reported DT-stabilized Au clusters. [39][40][41] The adsorption of Cu ions and the subsequent luminescence quenching is the main reason for this. [ 47 ] The XRD pattern showed all characteristic facets of fcc Au, whereas only the (001) facet of CuSe was observed ( Figure S8c, Supporting Information).…”

Towards Rational Design of Nanoparticle Catalysis in Ionic Liquids

“…For example, Au 15 , Au 18 , Au 25 [92], Au 38 [93] and Au 144 NCs [94] can all be prepared, and some of them have been fully characterized by single crystal X-ray diffraction [95]. These clusters break down the barriers between molecular systems and NP systems and are potential catalysts with unusual properties.…”