- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Insights into Interfaces, Stability, Electronic Properties, and Catalytic Activities of Atomically Precise Metal Nanoclusters from First Principles
摘要： Atomically precise, ligand-protected metal nanoclusters are of great interest for their well-defined structures, intriguing physicochemical properties, and potential applications in catalysis, biology, and nanotechnology. Their structure precision provides many opportunities to correlate their geometries, stability, electronic properties, and catalytic activities by closely integrating theory and experiment. In this Account, we highlight recent theoretical advances from our efforts to understand the metal?ligand interfaces, the energy landscape, the electronic structure and optical absorption, and the catalytic applications of atomically precise metal nanoclusters. We mainly focus on gold nanoclusters. The bonding motifs and energetics at the gold?ligand interfaces are two main interests from a computational perspective. For the gold?thiolate interface, the ?RS?Au?SR? staple motif is not always preferred; in fact, the bridging motif (?SR?) is preferred at the more open facets such as Au(100) and Au(110). This finding helps understand the diversity of the gold?thiolate motifs for different core geometries and sizes. A great similarity is demonstrated between gold?thiolate and gold?alkynyl interfaces, regarding formation of the staple-type motifs with PhC≡C? as an example. In addition, N-heterocyclic carbenes (NHCs) without bulky groups also form the staple-type motif. Alkynyls and bulky NHCs have the strongest binding with the gold surface from comparing 27 ligands of six types, suggesting a potential to synthesize NHC-protected gold clusters. The energy landscape of nanosystems is usually complex, but experimental progress in synthesizing clusters of the same Au?S composition with different R groups and isomers of the same Aun(SR)m formula have made detailed theoretical analyses of energetic contributions possible. Ligand?ligand interactions turn out to play an important role in the cluster stability, while metastable isomers can be obtained via kinetic control. Although the superatom-complex theory is the starting point to understand the electronic structure of atomically precise gold clusters, other factors also greatly affect the orbital levels that manifest themselves in the experimental optical absorption spectra. For example, spin?orbit coupling needs to be included to reproduce the splitting of the HOMO?LUMO transition observed experimentally for Au25(SR)18?, the poster child of the family. In addition, doping can lead to structural changes and charge states that do not follow the superatomic electron count. Atomically precise metal nanoclusters are an ideal system for understanding nanocatalysis due to their well-defined structures. Active sites and catalytic mechanisms are explored for selective hydrogenation and hydrogen evolution on thiolate-protected gold nanoclusters with and without dopants. The behavior of H in nanogold is analyzed in detail, and the most promising site to attract H is found to be coordinately unsaturated Au atoms. Many insights have been gained from first-principles studies of atomically precise, ligand-protected gold nanoclusters. Interesting and important questions remaining to be addressed are pointed out in the end.
关键词： atomically precise metal nanoclusters,gold nanoclusters,catalytic activities,first principles,metal?ligand interfaces,electronic properties
更新于2025-09-23 15:21:01
-
High-Resolution Shortwave Infrared Imaging of Vascular Disorders Using Gold Nanoclusters
摘要： We synthesized a generation of water-soluble, atomically precise gold nanoclusters (Au NCs) with anisotropic surface containing short dithiol pegylated chain (AuMHA/TDT). These AuMHA/TDT exhibit a high brightness (QY～6%) in the shortwave infrared (SWIR) spectrum with a detection above 1250 nm. Furthermore, they show an extended half-life in blood (t1/2? = 19.54 ±0.05 h) and a very weak accumulation in organs. We also developed a non-invasive, whole-body vascular imaging system in the SWIR window with high-resolution, benefiting from a series of Monte Carlo image processing of the images. The imaging process enabled to improve contrast by one order of magnitude and enhance by 59% the spatial resolution. After systemic administration of these nanoprobes in mice, we can quantify vessel complexity in depth (> 4 mm) allowing to detect very subtle vascular disorders non-invasively in bone morphogenetic 9 (Bmp9) deficient mice. The combination of these anisotropic surface charged gold nanoclusters plus an improved SWIR imaging device allows then a precise mapping at high resolution and in depth of the organization of the vascular network in live animals.
关键词： shortwave infrared fluorescence,bone morphogenetic 9 (Bmp9),gold nanoclusters,vascular disorder,monte carlo restoration imaging processing
更新于2025-09-23 15:21:01
-
Nanophysics in laser-induced cluster systems: topological quantum states in electrical conductivity and features of optical spectraa??theory and experiment for dimensional effects
摘要： Functional physical properties of laser-induced nanocluster structures of different topology in the thin films deposited on solid surface and 3D-crystallic structures by femto-nanoexperiments are studied. Physical basis and specific topology nanocluster view are under our consideration with regard to the functional properties variation (electrophysics + optics) in granular structures. Modeling of electronic energy levels modification due to the topology factors and nonlinear dynamic model for coupled electronic states in the cluster system are carried out. New physical principles for possible application of such structures of topological photonics with different element compositions are discussed.
关键词： Laser-induced nanoclusters,2D–3D-topology structures,Controllable functional properties of the objects,Femto-nanophotonics
更新于2025-09-23 15:21:01
-
[IEEE 2019 20th International Conference on Electronic Packaging Technology(ICEPT) - Hong Kong, China (2019.8.12-2019.8.15)] 2019 20th International Conference on Electronic Packaging Technology(ICEPT) - Self-Assembled Copper Nanoclusters-Based White Light Emitting Diodes With High Performance
摘要： Metal nanoclusters, composed of a few to a hundred atoms, whose size is close to the Fermi wavelength of electrons, have become a new type of phosphor materials due to their unique electronic structure and excellent performance. And metal nanoclusters have been applied in various applications, such as bioimaging, chemical biosensing, optoelectronic devices, etc. At present, researchers have synthesized and studied gold and silver nanoclusters, but Au and Ag nanoclusters have one drawback: expensive. At the same time, copper nanoclusters have attracted people's attention because of their non-toxicity, large Stokes shift and economy. In this paper, we fabricated 1-dodecanethiol (DT)-capped self-assembled copper nanoclusters in colloidal solution with yellow light emission and characterized the prepared self-assembled copper nanoclusters by UV–visible spectra, TEM and PL characterization methods. Self-assembled copper nanoclusters were used as color conversion layers for the manufacture of white light-emitting diodes. The prepared white LED has good color properties, the color rendering index was 79.3, the CIE color coordinates located at (0.3213,0.3255) and the color temperature was 6067K. This indicates that copper nanoclusters show potential for applications in white lighting emitting diodes as a new type of low-cost and superior photoluminescent material candidates.
关键词： Copper Nanoclusters,Photoluminescence,White Light Emitting Diodes,Quantum Dots
更新于2025-09-23 15:21:01
-
On the Formation of Amorphous Ge Nanoclusters and Ge Nanocrystals in GeSixOy Films on Quartz Substrates by Furnace and Pulsed Laser Annealing
摘要： Nonstoichiometric GeO0.5[SiO2]0.5 and GeO0.5[SiO]0.5 germanosilicate glassy films are produced by the high-vacuum coevaporation of GeO2 and either SiO or SiO2 powders with deposition onto a cold fused silica substrate. Then the films are subjected to furnace or laser annealing (a XeCl laser, λ = 308 nm, pulse duration of 15 ns). The properties of the samples are studied by transmittance and reflectance spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy. As shown by analysis of the Raman spectra, the GeO[SiO] film deposited at a substrate temperature of 100°C contains amorphous Ge clusters, whereas no signal from Ge–Ge bond vibrations is observed in the Raman spectra of the GeO[SiO2] film deposited at the same temperature. The optical absorption edge of the as-deposited GeO[SiO2] film corresponds to ~400 nm; at the same time, in the GeO[SiO] film, absorption is observed right up to the near-infrared region, which is apparently due to absorption in Ge clusters. Annealing induces a shift of the absorption edge to longer wavelengths. After annealing of the GeO[SiO2] film at 450°C, amorphous germanium clusters are detected in the film, and after annealing at 550°C as well as after pulsed laser annealing, germanium nanocrystals are detected. The crystallization of amorphous Ge nanoclusters in the GeO[SiO] film requires annealing at a temperature of 680°C. In this case, the size of Ge nanoclusters in this film are smaller than that in the GeO[SiO2] film. It is not possible to crystallize Ge clusters in the GeO[SiO] film. It seems obvious that the smaller the semiconductor nanoclusters in an insulating matrix, the more difficult it is to crystallize them. In the low-temperature photoluminescence spectra of the annealed films, signals caused by either defects or Ge clusters are detected.
关键词： crystallization,pulsed laser annealing,germanosilicate glasses,germanium nanoclusters
更新于2025-09-23 15:21:01
-
A Unique Pair: Ag40 and Ag46 Nanoclusters with the Same Surface but Different Cores for Structure-Property Correlation
摘要： Understanding the optical properties of nanoclusters is one of the central tasks in fundamental research. In this work, two new Ag nanoclusters that have distinctly different cores but a common protecting shell are [Ag40(2,4-DMBT)24(PPh3)8] and [Ag46(2,5-DMBT)24(PPh3)8]2+. Significantly, the Ag40 nanocluster comprises a simple cubic core of Ag8, which is for the first time observed experimentally. Using the Ag40 and Ag46 nanoclusters as a unique pair, we have investigated the effect of core structure on the optical absorption properties of these nanoclusters. The compact core-shell in Ag46 makes the frontier orbitals highly degenerate, whereas the loose core-shell of Ag40 leads to much less degeneracy in the frontier orbits. Also, with the difference in the core structure, these two silver nanoclusters show different catalytic activity in the oxygen reduction reaction. Overall, this work reveals that the core packing mode plays a significant role in determining the optical of metal nanoclusters. The new materials with controlled crystalline phases also hold promise in other applications.
关键词： Ag nanoclusters,crystalline phases,core structure,optical properties,catalytic activity
更新于2025-09-23 15:21:01
-
Alkali Metal Ions: A Secret Ingredient for Metal Nanocluster-Sensitized Solar Cells
摘要： The presence of alkali metal ions (AMIs) during the adsorption of thiolated Au nanoclusters (NCs) onto TiO2 plays a critical role in achieving high power conversion efficiency and suppressing anomalous current?voltage hysteresis in metal nanocluster-sensitized solar cells. This hidden role of the AMIs is intimately related to the adsorption strength between the NCs and TiO2, indicating the importance of seeking a comprehensive understanding of NC?TiO2 interfaces and devising interfacial engineering techniques to support the next advance in light energy conversion applications of NCs.
关键词： alkali metal ions,metal nanoclusters,current?voltage hysteresis,power conversion efficiency,solar cells
更新于2025-09-23 15:21:01
-
Copper nanoclusters @ nitrogen-doped carbon quantum dots-based ratiometric fluorescence probe for lead (II) ions detection in porphyra
摘要： A novel ratiometric fluorescence probe was proposed for detecting lead (II) ions (Pb2+) in porphyra, the approach was based on copper nanoclusters and nitrogen-doped carbon quantum dots (CuNCs-CNQDs). In this probe, the CuNCs delivered the response signal, the fluorescence of which was enhanced by Pb2+ due to the aggregation-induced emission enhancement (AIEE) between Pb2+ and CuNCs. The CNQDs provided the self-calibration signal, whose fluorescence remained almost unchanged in coexistence with Pb2+. According to the change of fluorescence intensity ratio between the fluorophores, CuNCs–CNQDs nanohybrid was used as ratiometric probes for the sensitive detection of Pb2+ in the range of 0.010 to 2.5 mg L-1, with a detection limit of 0.0031 mg L-1. Finally, the probe was successfully applied to detect Pb2+ in porphyra with relative standard deviations (RSDs) lower than 5%. This study provides a straightforward, stable, and sensitive approach for detecting Pb2+ in porphyra.
关键词： Lead (II) ions,Ratiometric fluorescence probe,Aggregation-induced emission enhancement,Copper nanoclusters,Nitrogen-doped carbon quantum dots
更新于2025-09-23 15:21:01
-
Vibrational Properties of Thiolate-Protected Gold Nanoclusters
摘要： Over recent years, the field of thiolate-protected gold nanoclusters has made remarkable progress. The successful determination of the structure of some of these clusters by X-ray crystallography was a milestone in this field. X-ray crystallography is arguably the most important technique in the field up to now, and it enabled the study of structure evolution as a function of cluster size. It also shed light on the structure of the Au?S interface. Recently, it has been realized that thiolate-protected gold clusters are very dynamic systems. Metal atoms and ligands can exchange easily between clusters. Furthermore, the adsorbed ligands bear conformational dynamics. Such dynamic effects call for experimental methods that can cope with it. Future efforts in this field will be directed toward applications of thiolate-protected clusters, and many of them will rely on dissolved clusters. Therefore, structure determination in solution is an important issue, though it is very challenging. The structure of the metal core and the Au?S interface is not expected to change in solution with respect to the crystal. However, the structure of the adsorbed ligand itself is sensitive to the environment and may be different in the solid state and in solution, as has been shown in fact in the past. It is this (dynamic) structure of the ligand that determines the interaction between the cluster and its environment, which is crucial, for example, for sensing applications. Vibrational spectroscopy is a promising technique to characterize thiolate-protected clusters in different environments. A vibrational spectrum is sensitive to structure (conformation) although this information is often 'hidden' in the spectrum, requiring detailed analysis and support from theory to be deciphered. Compared to other techniques like UV?vis spectroscopy and mass spectrometry, vibrational spectroscopy was not extensively used in the field of thiolate-protected clusters, but we believe that the technique will be very valuable for the future developments in the field.
关键词： vibrational spectroscopy,ligand conformation,thiolate-protected gold nanoclusters,Au?S interface,chirality transfer
更新于2025-09-23 15:21:01
-
Aprotinin Encapsulated Gold Nanoclusters: A Fluorescent Bioprobe with Dynamically Nuclear Targeting and Selective Detection of Trypsin and Heavy Metal
摘要： Fluorescence imaging has currently emerged as one of the most frequently used noninvasive imaging technology to selectively monitor biological processes in living systems. In past decades, gold nanoclusters (Au NCs) received increasing attraction because of their intrinsic fluorescence and their inherent biocompatibility. As a stabilizing and reducing agent, an abundant, sustainable and widely used polypeptide derived drug molecule, aprotinin (Ap) is selected for the synthesis of Au nanoclusters (Ap-Au NCs) due to characteristic bioactivity, excellent biocompatibility, biodegradability, nonallergenic character. Herein, Ap encapsulated Au NCs exhibiting desirable red fluorescence feature was facilely produced for the first time, which were subsequently used for cell imaging and detection of various analytes. Much interestingly, dynamically subcellular localization of Ap-Au NCs from the cytoplasm to the nucleus in Hela cells was observed. Afterward, it has shown the selective and quantitative detection of trypsin by using Ap encapsulated Au NCs. Lastly, Ap-Au NCs were readily used for detection of mercury and copper quantitatively. The photoluminescence of the Ap-Au NCs was quenched with the addition of metioned analytes. This study opens crucial insights on the integration of biomolecule with metal nanoclusters, also discusses a multifunctional nanomaterial platform for cell imaging, subcellular targeting, biosensing and drug delivery.
关键词： trypsin detection,gold nanoclusters,aprotinin,cell imaging,heavy metal detection,Fluorescence imaging
更新于2025-09-23 15:21:01