Photochemical Route for Synthesizing Atomically Precise Metal Nanoclusters from Disulfide

Abstract

Practical approaches to the synthesis of atomically precise metal nanoclusters are in high demand as they provide the structural basis for investigating nanomaterials’ structure–property correlations with atomic precision. The Brust–Schiffrin method has been widely used, while the essential reductive ligands (e.g., thiols) limit the application of this method for synthesizing metal nanoclusters with specific frameworks and surface ligands. In this work, we developed a photochemical route for synthesizing atomically precise metal nanoclusters by applying disulfide, which is a widely available, stable, and environmentally friendly sulfur source. This method enables the construction of structurally diverse metal nanoclusters and especially features the synthesis of PhS-protected metal nanoclusters that were not easily achieved previously and the gram-scale synthesis. A reduction–oxidation cascade mechanism has been revealed for the photochemical route. This work is expected to open up new opportunities for metal nanocluster synthesis and will contribute to the practical applications of this kind of nanomaterial.

Reduction–Oxidation Cascade Strategy for Reforming a Au13-Kerneled Gold Thiolate Nanocluster

“…This, along with the results from the theoretical analysis of the electronic structures and the experimental results on the stability of Au 23 , Au 22 and Au 20 (FigureS13), shows why the quartet tetrahedron Au 14 kernel is considered to be more stable and rigid than the sandwich Au 13 kernel, 50−52 thus restricting the intramolecular rotation and vibration of Au 20 and endowing it with a higher emission intensity.53−55 Moreover, Au 20 contains four chloride atoms, which are not involved in Au 23 and Au 22 . Abundant intramolecular Cl•••H interactions have been observed in Au 20 (FigureS12), which also contribute to the rigidity of the Au 20 nanocluster.56−58 Interestingly, we developed a direct synthesis method for the construction of structurally diversified gold nanoclusters in a very recent work,59 in which a reduction−oxidation cascade mechanism was also revealed. The gold precursor HAuCl 4 was initially reduced by NaBH 4 and then oxidized by the in situ generated sulfur radicals (e.g., PhS•), forming gold nanoclusters.…”

“…53 S12), which also contribute to the rigidity of the Au 20 nanocluster. 56−58 Interestingly, we developed a direct synthesis method for the construction of structurally diversified gold nanoclusters in a very recent work, 59 in which a reduction−oxidation cascade mechanism was also revealed. The gold precursor HAuCl 4 was initially reduced by NaBH 4 and then oxidized by the in situ generated sulfur radicals (e.g., PhS•), forming gold nanoclusters.…”

Photochemical synthesis of group 10 metal nanoclusters for electrocatalysis

“…30–35 Inspired from the pioneer work on the photo-induced construction of metal nanoclusters, 36–39 very recently, we developed a photochemical route for synthesizing atomically precise group 11 metal nanoclusters from disulfides. 40 The mechanism of this method is different from that of the previous methods on photo-induced or two-step reduction synthesis, and undergoes a reduction–oxidation cascade process (Fig. 1B).…”

“…1C). Based on our previous report, 40 NaBH 4 would preliminarily reduce and gather the nickel precursors to Ni aggregates. The subsequential LED irradiation would convert PhSSPh to PhS˙ radicals, which abstract electrons from the polydisperse Ni aggregates to form the monodisperse Ni nanocluster.…”

“…The Ni II precursor is difficult to be oxidized by the PhS˙ radicals, thus resulting in annihilation of the active PhS˙ radicals. 40 Therefore, the reduction–oxidation sequence is also important for the photochemical synthesis. Notably, the photochemical synthesis was conducted under quite mild conditions, circumventing low temperature or inert gas protection that are essential in the conventional methods.…”