There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Metal species with different size (single atoms, nanoclusters, and nanoparticles) show different catalytic behavior for various heterogeneous catalytic reactions. It has been shown in the literature that many factors including the particle size, shape, chemical composition, metal–support interaction, and metal–reactant/solvent interaction can have significant influences on the catalytic properties of metal catalysts. The recent developments of well-controlled synthesis methodologies and advanced characterization tools allow one to correlate the relationships at the molecular level. In this Review, the electronic and geometric structures of single atoms, nanoclusters, and nanoparticles will be discussed. Furthermore, we will summarize the catalytic applications of single atoms, nanoclusters, and nanoparticles for different types of reactions, including CO oxidation, selective oxidation, selective hydrogenation, organic reactions, electrocatalytic, and photocatalytic reactions. We will compare the results o...

Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles.

Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1–3 nm in diameter, often called nanoclusters). This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties of atomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles (such as the s...

Atomically Precise Colloidal Metal Nanoclusters and Nanoparticles: Fundamentals and Opportunities

인공고관절의 세라믹 볼 헤드의 기계적 안정성 평가를 위한 3 차원 유한요소 해석

Atomically precise pieces of matter of nanometer dimensions composed of noble metals are new categories of materials with many unusual properties. Over 100 molecules of this kind with formulas such as Au25(SR)18, Au38(SR)24, and Au102(SR)44 as well as Ag25(SR)18, Ag29(S2R)12, and Ag44(SR)30 (often with a few counterions to compensate charges) are known now. They can be made reproducibly with robust synthetic protocols, resulting in colored solutions, yielding powders or diffractable crystals. They are distinctly different from nanoparticles in their spectroscopic properties such as optical absorption and emission, showing well-defined features, just like molecules. They show isotopically resolved molecular ion peaks in mass spectra and provide diverse information when examined through multiple instrumental methods. Most important of these properties is luminescence, often in the visible–near-infrared window, useful in biological applications. Luminescence in the visible region, especially by clusters prot...

Atomically Precise Clusters of Noble Metals: Emerging Link between Atoms and Nanoparticles

Mass Spectrometry of Au10(4-tert-butylbenzenethiolate)10 Nanoclusters Using Superconducting Tunnel Junction Cryodetection Reveals Distinct Metastable Fragmentation.

Precision synthesis of a CdSe semiconductor nanocluster via cation exchange

http://absimage.aps.org/image/MAR17/MWS_MAR17-2016-002350.pdf

Evolution from the Plasmon to Exciton State in Atomically Precise Gold Nanoparticles

CdTe magic-sized clusters (MSCs) are promising building blocks for semiconductor devices because of their single size, consistent properties, and reproducible synthesis. However, the synthetic conditions for CdTe MSCs vary significantly in different reports, which hinders the general understanding of their formation mechanisms. Here, we employed Cd(oleate)2, trioctylphosphine telluride (TOPTe), and oleylamine, which are commonly used for larger quantum dot (QD) synthesis, as standard reaction precursors, and systematically investigated the effects of solvent, phosphine amount, oleylamine amount, Cd : Te ratio, and temperature on the evolution of MSCs with time. These conditions compose the "reaction coordinates" to map out the "reaction zones" for CdTe MSCs and QDs. We found that CdTe MSCs with the first excitonic transition (E1) at 449 nm can be synthesized in high purity with excess TOPTe using toluene as the solvent at 100 °C. Whereas higher temperature, excess of Cd(oleate)2, or more viscous solvent led to the aggregation of 449 nm MSC into larger magic-sized species with E1 at 469 nm as well as QDs with E1 > 500 nm. Increasing phosphine concentration simply enhanced the rate and yield of CdTe MSCs, while a critical amount of oleylamine was required to "turn on" the MSC formation. Interestingly, the pure 449 nm MSCs were non-emissive, but colorful emissions were observed for the reaction mixtures containing both MSCs and QDs. The emissions could be attributed to a small amount of QDs formed during the reaction. The mapping of reaction zones is a crucial step towards the rational synthesis of CdTe MSCs and further understanding of their formation mechanism.

Chenjie Zeng

Papers

Mass Spectrometry of Au10(4-tert-butylbenzenethiolate)10 Nanoclusters Using Superconducting Tunnel Junction Cryodetection Reveals Distinct Metastable Fragmentation.

Precision synthesis of a CdSe semiconductor nanocluster via cation exchange

Evolution from the Plasmon to Exciton State in Atomically Precise Gold Nanoparticles

Mapping the reaction zones for CdTe magic-sized clusters and their emission properties.

Nanocluster superstructures assembled via surface ligand switching at high temperature