Kinetically Controlled, High-Yield Synthesis of Au<sub>25</sub> Clusters

Zhu, Manzhou; Lanni, Eric J.; Garg, Niti; Bier, Mark E.; Jin, Rongchao

doi:10.1021/ja0782448

Cited by 541 publications

(594 citation statements)

References 22 publications

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“…For the synthesis of Au 25 (SR) 18 nanoclusters, a kinetically controlled, size-focusing approach was used. 27 The structure of Au 25 (SR) 18 has been reported in our previous work. 11 Supported Au n (SR) m /MO x (including TiO 2 , CeO 2 , Fe 2 O 3 ) catalysts were prepared as follows: 500 mg of the oxide support (in powder form) was impregnated by soaking the powders in a solution of 5À10 mg Au n (SR) m nanoclusters in CH 2 Cl 2 (ca.…”

Section: Methodsmentioning

confidence: 81%

“…The synthesis of atomically precise Au 25 (SR) 18 (R = CH 2 CH 2 Ph) nanoclusters follows a size-focusing method reported previously, 27 and the crystal structures of anionic and charge-neutral Au 25 (SR) 18 nanoclusters have been determined by X-ray crystallography. 11,24 The oxide-supported catalysts were made by impregnation of metal oxide powder in a solution of Au 25 (SR) 18 nanoclusters (see Experimental Section for details).…”

Section: Resultsmentioning

confidence: 99%

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CO Oxidation Catalyzed by Oxide-Supported Au₂₅(SR)₁₈ Nanoclusters and Identification of Perimeter Sites as Active Centers

et al. 2012

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In this work, we explore the catalytic application of atomically monodisperse, thiolate-protected Au 25 (SR) 18 (where R = CH 2 CH 2 Ph) nanoclusters supported on oxides for CO oxidation.The solution phase nanoclusters were directly deposited onto various oxide supports (including TiO 2 , CeO 2 , and Fe 2 O 3 ), and the as-prepared catalysts were evaluated for the CO oxidation reaction in a fixed bed reactor. The supports exhibited a strong effect, and the Au 25 (SR) 18 /CeO 2 catalyst was found to be much more active than the others. Interestingly, O 2 pretreatment of the catalyst at 150 °C for 1.5 h significantly enhanced the catalytic activity. Since this pretreatment temperature is well below the thiolate desorption temperature (∼200 °C), the thiolate ligands should remain on the Au 25 cluster surface, indicating that the CO oxidation reaction is catalyzed by intact Au 25 (SR) 18 /CeO 2 . We further found that increasing the O 2 pretreatment temperature to 250 °C (above the thiolate desorption temperature) did not lead to any further increase in activity at all reaction temperatures from room temperature to 100 °C. These results are in striking contrast with the common thought that surface thiolates must be removed ; as is often done in the literature work ; before the catalyst can exert high catalytic activity. The 150 °C O 2pretreated Au 25 (SR) 18 /CeO 2 catalyst offers ∼94% CO conversion at 80 °C and ∼100% conversion at 100 °C. The effect of water vapor on the catalytic performance is also investigated. Our results imply that the perimeter sites of the interface of Au 25 (SR) 18 /CeO 2 should be the active centers.The intact structure of the Au 25 (SR) 18 catalyst in the CO oxidation process allows one to gain mechanistic insight into the catalytic reaction.

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Section: Methodsmentioning

confidence: 81%

Section: Resultsmentioning

confidence: 99%

CO Oxidation Catalyzed by Oxide-Supported Au₂₅(SR)₁₈ Nanoclusters and Identification of Perimeter Sites as Active Centers

et al. 2012

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“…We also synthesized a series of molecular Au clusters of Au 25 (SC 2 H 4 Ph) 18 , Au 38 (SC 2 H 4 Ph) 24 and Au 144 (SC 2 H 4 Ph) 60 and employed them as precursors to porous carbon-supported Au nanoparticles with different sizes toward oxygen reduction [63]. The ORR performances of Au 25 (SC 2 H 4 Ph) 18 , Au 38 (SC 2 H 4 Ph) 24 , Au 144 (SC 2 H 4 Ph) 60 and the resulting AuPC-1, AuPC-2 and AuPC-3 samples are summarized in Table 3. One can see that, due to restraint of the surface thiolate ligand, the three molecular Au clusters exhibited relatively low ORR activity with Au 25 (SC 2 H 4 Ph) 18 being the best.…”

Section: Au Clusters For Orrmentioning

confidence: 99%

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

Tang

Wang

2018

Catalysts

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Highly-efficient catalysts for the oxygen reduction reaction (ORR) have been extensively investigated for the development of proton exchange membrane fuel cells (PEMFCs). The state-ofthe-art Pt/C catalysts suffer from high price, limited accessibility of Pt, sluggish reaction kinetics, as well as undesirable long-term durability. Engineering ultra-small noble metal clusters with high surface-to-volume ratios and robust stabilities for ORR represents a new avenue. After a simple introduction regarding the significance of ORR and the recent development of noble metal clusters, the general ORR mechanism in both acidic and basic media is firstly discussed. Subsequently, we will summarize the recent efforts employing Pt, Au, Ag, Pd and Ru clusters, as well as the alloyed bi-metallic clusters for acquiring highly efficient catalysts to enhance both the activity and stability of ORR. Molecular noble metal clusters with definitive composition to reveal the relevant ORR mechanism will be particularly highlighted. Finally, the current challenges, the future outlook, as well as the perspectives in this booming field will be proposed, featuring the great opportunities and potentials to engineering noble metal clusters as highly-efficient and durable cathodic catalysts for fuel cell applications.

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“…Quantum clusters are a new class of nanomaterials with only a few atoms in the core and are represented in terms of the number of core atoms such as Au 8 [6 9], Au 11 [10 14], Au 13 [15 17] or Au 25 [18 25], rather than their core diameter. Having sub-nanometer size, they cannot possess surface plasmon resonance as the density of states is insufficient to create metallicity.…”

mentioning

confidence: 99%

“…Of the various possible clusters synthesized by different methods, some specifi c clusters are extremely stable compared to others. For example, Au 25 SG 18 , where 334 Nano Res (2008) 1: 333 340…”

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confidence: 99%

Two distinct fluorescent quantum clusters of gold starting from metallic nanoparticles by pH-dependent ligand etching

et al. 2008

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Two fl uorescent quantum clusters of gold, namely Au 25 and Au 8 , have been synthesized from mercaptosuccinic acid-protected gold nanoparticles of 4 5 nm core diameter by etching with excess glutathione. While etching at pH ~3 yielded Au 25 , that at pH 7 8 yielded Au 8 . This is the fi rst report of the synthesis of two quantum clusters starting from a single precursor. This simple method makes it possible to synthesize well-defined clusters in gram quantities. Since these clusters are highly fl uorescent and are highly biocompatible due to their low metallic content, they can be used for diagnostic applications. KEYWORDSGold cluster, glutathione, pH, ligand etching, fl uorescence Nanoparticles with a variety of shapes and sizes have been synthesized as they offer numerous possibilities to study size and shape-dependent variations of electronic [1], optical [2], and chemical properties [3 5]. Quantum clusters are a new class of nanomaterials with only a few atoms in the core and are represented in terms of the number of core atoms such as Au 8 This gram-quantity synthetic approach makes it possible to undertake a range of studies on this class of novel materials. Au@MSA in water was mixed with GSH, 1:4 by weight, in air, under constant stirring at 55 °C. The pH of the starting solution was in the range 2.7 3. The UV vis spectrum was measured at regular intervals during etching. The starting material, Au@ MSA showed a surface plasmon resonance at 540 nm ( Fig. 1), characteristic of metallic nanoparticles. It was found that the surface plasmon resonance at 540 nm disappeared gradually within a few hours and new absorption features started to appear. After etching twice with glutathione, stable and well-defined peaks similar to Au 25 were obtained (see Electronic Supplementary Material (ESM), Fig. S-1) and the surface plasmon resonance disappeared completely. The color of the solution changed from dark brown to reddish brown. A precipitate formed when the mixture was cooled to room temperature, due to the formation of a polymeric gold thiolate. This was centrifuged out and methanol was added to the supernatant to precipitate the clusters. After washing with methanol and ethanol in succession, the sample was freeze dried to afford a dark reddish brown powder. It was redissolved in water and its UV-vis spectrum showed peaks characteristic of Au 25 SG 18 ( Fig. 1) with all the well-structured features and characteristic absorption maximum at 672 nm. Thus it can be concluded that the etching of Au@MSA nanoparticles resulted in the formation of highly water-soluble Au 25 clusters. The peak at 672 nm (1.55 eV) arises due to the LUMO HOMO transition which can be called an intra-band (sp sp) transition [19,27]. The features in the lower wavelength region arise due to inter-band transitions (sp d). The etching was also carried out at pH 8. In this case, GSH was added to Au@MSA, 1:4 by weight and the pH was adjusted to 8 by adding NaOH. The color of the solution turned to pale green after 15 20 hours of heating a...

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Kinetically Controlled, High-Yield Synthesis of Au₂₅ Clusters

Cited by 541 publications

References 22 publications

CO Oxidation Catalyzed by Oxide-Supported Au₂₅(SR)₁₈ Nanoclusters and Identification of Perimeter Sites as Active Centers

CO Oxidation Catalyzed by Oxide-Supported Au₂₅(SR)₁₈ Nanoclusters and Identification of Perimeter Sites as Active Centers

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

Two distinct fluorescent quantum clusters of gold starting from metallic nanoparticles by pH-dependent ligand etching

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Kinetically Controlled, High-Yield Synthesis of Au25 Clusters

Cited by 541 publications

References 22 publications

CO Oxidation Catalyzed by Oxide-Supported Au25(SR)18 Nanoclusters and Identification of Perimeter Sites as Active Centers

CO Oxidation Catalyzed by Oxide-Supported Au25(SR)18 Nanoclusters and Identification of Perimeter Sites as Active Centers

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

Two distinct fluorescent quantum clusters of gold starting from metallic nanoparticles by pH-dependent ligand etching

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Product

Resources

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Kinetically Controlled, High-Yield Synthesis of Au₂₅ Clusters

CO Oxidation Catalyzed by Oxide-Supported Au₂₅(SR)₁₈ Nanoclusters and Identification of Perimeter Sites as Active Centers

CO Oxidation Catalyzed by Oxide-Supported Au₂₅(SR)₁₈ Nanoclusters and Identification of Perimeter Sites as Active Centers