Nanocluster Materials Research Articles

Advancing electrochemical CO2 reduction with group 11 metal nanoclusters for renewable energy solutions

AbstractUnderstanding the intricate relationship between structure and properties is paramount in distinguishing nanocluster (NC) materials from their counterparts. Despite the progress in synthesizing new NCs, the sluggish exploration of their potential applications persists due to the difficulty in stabilizing these materials. However, recent investigations have unveiled their remarkable efficacy as catalysts in electrochemical CO2 reduction reactions, surpassing traditional materials. This discovery, addressing urgent global concerns, has quickly drawn significant attention to this field, leading to its rapid expansion. Hence, there is an urgent need to outline this research landscape and pinpoint effective strategies, marking a significant advancement. In this context, our endeavor is dedicated to offering researchers a thorough understanding of recently synthesized NC materials. We aim to elucidate their distinct structural architectures and associated properties essential for catalyst design. We envision that this systematic review will serve as a guiding beacon for future research endeavors in this burgeoning field.

Evolution of Excited-State Behaviors of Gold Complexes, Nanoclusters and Nanoparticles.

Metal nanomaterials have been extensively investigated owing to their unique properties in contrast to bulk counterparts. Gold nanoparticles (e. g., 3-100 nm) show quasi-continuous energy bands, while gold nanoclusters (<3 nm) and complexes exhibit discrete energy levels and display entirely different photophysical properties than regular nanoparticles. This review summarizes the electronic dynamics of these three types of gold materials studied by ultrafast spectroscopy. Briefly, for gold nanoparticles, their electronic relaxation is dominated by heat dissipation between the electrons and the lattice. In contrast, gold nanoclusters exhibit single-electron transitions and relatively long excited-state lifetimes being analogous to molecules. In gold complexes, the excited-state dynamics is dominated by intersystem crossing and phosphorescence. A detailed understanding of the photophysical properties of gold nanocluster materials is still missing and thus calls for future efforts. The fundamental insights into the discrete electronic structure and the size-induced evolution in quantum-sized nanoclusters will promote the exploration of their applications in various fields.

Structure control and evolution of atomically precise gold clusters as heterogeneous precatalysts.

Metal clusters have distinct features from single atom and nanoparticle (>1 nm) catalysts, making them effective catalysts for various heterogeneous reactions. Nevertheless, the ambiguity and complexity of the catalyst structure preclude in-depth mechanistic studies. The evolution of metal species during synthesis and reaction processes represents another challenge. One effective solution is to precisely control the structure of the metal cluster, thus offering a well-defined pre-catalyst. The well-defined chemical formula and configurations make atomically precise metal nanoclusters optimal choices. To fabricate an atomically precise metal nanocluster-based heterogeneous catalyst with enhanced performance, careful structural design of both the nanocluster and support material, an effective assembling technique, and a pre-treatment method for these hybrids need to be developed. In this review, we summarize recent advances in in the development of heterogeneous catalysts using atomically precise gold and alloy gold nanoclusters as precursors. We will begin with a brief introduction to the structural properties of atomically precise nanoclusters and structure determination of cluster/support hybrids. We will then introduce heterogeneous catalysts prepared from medium size (tens to hundreds of metal atoms) and low nuclearity nanoclusters. We will illustrate how ligand modification, support-cluster interaction, hybrid fabrication, and heteroatom (Pt, Pd Ag, Cu, Cd, Fe) introduction affect the structural properties and pretreatment/reaction-induced structural evolution of gold nanocluster pre-catalysts. Lastly, we will highlight the synthetic method of NCs@MOF hybrids and their effectiveness in circumventing the adverse cluster structural evolution. These findings are expected to shed light on the structure-activity relationship studies and future catalyst design strategies using atomically precise metal nanocluster pre-catalysts.

Nanocluster catalysts for the electrochemical conversion of carbon dioxide

Nanocluster materials for CO2 electroreduction are analyzed with a focus on rational design, considering size effects and stronger interactions with reaction intermediates, electrolytes, and support materials.

Research progress in photocatalytic reduction of CO2 based on metal nanocluster materials

Photocatalytic reduction of carbon dioxide into hydrocarbons with higher added values offers an effective strategy for mitigating greenhouse effects and addressing energy crises. Compared to other CO2 conversion methods, photocatalytic...

An integrated optical and chromogenic probe for tumor cell imaging

Tumor cell heterogeneity determines the prognosis and metastasis of the tumor. It is pivotal to develop an innovative and facile cell imaging probe for cell and tumor tissue imaging. Combined the fluorescent properties, enzyme-like catalytic activity of Au nanocluster materials and the catalytic activity of Iron-based nanoparticles to establish an integrated probe is novel work for tumor cell multi-modal imaging. Herein, we developed a facile method to prepare Au/Fe integrated probe using BSA as a template. By the optimization of the experimental conditions, the Au/Fe integrated multi-functional imaging probe was successfully synthesized. The bio-safety and enzyme-like catalysis were also explored. The results showed that the Au/Fe integrated probe possess good fluorescent, biosecurity and enzyme-like catalysis property. Meanwhile, the Au/Fe integrated probe exhibited excellent tumor cell optical and chromogenic imaging ability. The results suggested that the prepared Au/Fe integrated multi-functional imaging probe is a promising candidate for biolabeling of the biological sample.

Computational exploration of gallium-doped neutral and anionic magnesium nanocluster materials: Ga2Mgnq (n = 1–11; q=0, −1) nanocluster’s properties based on DFT

In this study, using CALYPSO software to search initial structures of the gas-phase Ga2Mgnq (n = 1–11; q=0, −1) nanoclusters in vacuum, both neutral and anionic magnesium nanoclusters doped with two gallium atoms based on DFT were systematically investigated. According to the structural optimization calculations, the ground state structures of Ga2Mgnq nanoclusters evolve from 2D plane structures to 3D tetrahedron-based geometries before stabilizing at 3D triangular prism-based structures. Stability analysis indicates that Ga2Mg8 and Ga2Mg7- are robust and, therefore, could be categorized as "magic" clusters. Based on MOs, DOS and AdNDP computations, it is found that the σ-type chemical bond formed by the hybridization of the s- and p-orbitals of Ga and Mg atoms are responsible for the high stability of Ga2Mg8 and Ga2Mg7-. Furthermore, to provide further support for future experiments, the PES of Ga2Mgnq=−1 (n = 1–11) and IR and Raman spectra of Ga2Mg8 and Ga2Mg7- nanoclusters were also reported.

Observation of Core Phonon in Electron-Phonon Coupling in Au25 Nanoclusters.

Temperature-dependent optical properties are of paramount importance for fundamentally understanding the electron-phonon interactions and phonon modes in atomically precise nanocluster materials. In this work, low-temperature optical absorption spectra of the icosahedral [Au25(SR)18]- nanocluster are measured from room temperature down to liquid helium temperature by adopting a thin-film-based technique. The thin-film measurement is further compared with results from the previous solution-based method. Interestingly, the previously missing core phonon is revealed by a quantitative analysis of the film data through peak deconvolution and fitting of the temperature trend with a theoretical model. The two lowest-energy absorption peaks (at 1.6 and 1.8 eV) of Au25 are determined to couple with the staple-shell phonon (average energy ∼350 cm-1) in the solution state, but in the solid state these electronic transitions couple with the core phonon (average energy ∼180 cm-1). The suppression of the staple-shell phonon in the solid state is attributed to the intracluster and cluster-matrix interactions.

P band intermediate state (PBIS) tailors photoluminescence emission at confined nanoscale interface

The availability of a range of excited states has endowed low dimensional quantum nanostructures with interesting luminescence properties. However, the origin of photoluminescence emission is still not fully understood, which has limited its practical application. Here we judiciously manipulate the delicate surface ligand interactions at the nanoscale interface of a single metal nanocluster, the superlattice, and mesoporous materials. The resulting interplay of various noncovalent interactions leads to a precise modulation of emission colors and quantum yield. A new p-band state, resulting from the strong overlapping of p orbitals of the heteroatoms (O, N, and S) bearing on the targeting ligands though space interactions, is identified as a dark state to activate the triplet state of the surface aggregated chromophores. The UV-Visible spectra calculated by time-dependent density functional theory (TD-DFT) are in quantitative agreement with the experimental adsorption spectra. The energy level of the p-band center is very sensitive to the local proximity ligand chromophores at heterogeneous interfaces.

Osteoporotic Bone Recovery by a Highly Bone-Inductive Calcium Phosphate Polymer-Induced Liquid-Precursor.

Osteoporosis is an incurable chronic disease characterized by a lack of mineral mass in the bones. Here, the full recovery of osteoporotic bone is achieved by using a calcium phosphate polymer‐induced liquid‐precursor (CaP‐PILP). This free‐flowing CaP‐PILP material displays excellent bone inductivity and is able to readily penetrate into collagen fibrils and form intrafibrillar hydroxyapatite crystals oriented along the c‐axis. This ability is attributed to the microstructure of the material, which consists of homogeneously distributed ultrasmall (≈1 nm) amorphous calcium phosphate clusters. In vitro study shows the strong affinity of CaP‐PILP to osteoporotic bone, which can be uniformly distributed throughout the bone tissue to significantly increase the bone density. In vivo experiments show that the repaired bones exhibit satisfactory mechanical performance comparable with normal ones, following a promising treatment of osteoporosis by using CaP‐PILP. The discovery provides insight into the structure and property of biological nanocluster materials and their potential for hard tissue repair.

Ethyl acetate-induced formation of amorphous MoSx nanoclusters for improved H2-evolution activity of TiO2 photocatalyst

Amorphous MoSx has been demonstrated to be a high H2-production cocatalyst towards various photocatalytic materials, and the facile synthetic route of MoSx cocatalyst with a small size is highly required to further improve its H2-evolution performance. In this study, amorphous MoSx nanoclusters (a-MoSx) with a very small size of 0.4–0.7 nm have been successfully loaded on TiO2 surface by an ethyl acetate-induced hydrolysis route. Herein, the MoS42− ions can be gradually and homogeneously transformed into amorphous MoSx nanoclusters on the TiO2 surface to prepare the highly efficient a-MoSx/TiO2 photocatalysts via the gradual hydrolysis of ethyl acetate. The photocatalytic hydrogen-production experimental results reveal that the resulting a-MoSx/TiO2 (5 wt%) photocatalyst achieves the maximum H2-evolution rate (1106 μmol h−1 g−1), which is apparently higher than that of crystalline MoSx-modified TiO2 (94 μmol h−1 g−1) by a factor of 11.71 times. The markedly enhanced H2-evolution rate of the a-MoSx/TiO2 photocatalyst can be attributed to the formation of more unsaturated S atoms in the amorphous MoSx nanoclusters, which can work as effective active sites to boost the interfacial H2-production rate. The present facile method may provide rational ideas for preparing other nanocluster materials for energy and environmental applications.

Synthesis of multivalent sialyllactosamine-carrying glyco-nanoparticles with high affinity to the human influenza virus hemagglutinin

A series of multivalent sialoglyco-conjugated nanoparticles were efficiently synthesized by using highly-branched α-glucuronic acid-linked cyclic dextrins (GlcA-HBCD) as a backbone. The sialoglycoside-moieties, with varying degrees of substitution, could be incorporated onto the preformed nanoparticles. These synthesized particles, which are highly soluble in aqueous solution, were shown to have a spherical nanostructure with a diameter of approximately 15nm. The interactions of the sialoglyco-nanoparticles (Neu5Acα2,6LacNAc-GlcA-HBCDs) with human influenza virus strain A/Beijing/262/95 (H1N1) were investigated using a hemagglutination inhibition assay. The sialoglyco-nanoparticle, in which the number of sialic acid substitution is 30, acted as a powerful inhibitor of virus binding activity. We show that both distance and multiplicity of effective ligand-virus formation play important roles in enhancing viral inhibition. Our results indicate that the GlcA-HBCD backbone can be used as a novel spherical nanocluster material for preparing a variety of glyco-nanoparticles to facilitate molecular recognition.

Metal/Metal-Oxide Nanoclusters for Gas Sensor Applications

The development of gas sensors that are based on metal/metal-oxide nanoclusters has attracted intensive research interest in the last years. Nanoclusters are suitable candidates for gas sensor applications because of their large surface-to-volume ratio that can be utilized for selective and rapid detection of various gaseous species with low-power consuming electronics. Herein, nanoclusters are used as building blocks for the construction of gas sensor where the electrical conductivity of the nanoclusters changes dramatically upon exposure to the target gas. In this review, recent progress in the fabrication of size-selected metallic nanoclusters and their utilization for gas sensor applications is presented. Special focus will be given to the enhancement of the sensing performance through the rational functionalization and utilization of different nanocluster materials.

Synthesis of Li4Ti5O12 nanoclusters for lithium-ion batteries with excellent electrochemical performances

Li4Ti5O12 nanoclusters are successfully prepared by a facile solution-based method and subsequent calcination. The influences of calcination temperatures on the microstructure and electrochemical performance of the products are studied. Results indicate that the sample annealed at 700°C exhibits outstanding rate performances and excellent long-term cycle stabilities. It displays a high initial Coulombic efficiency of 96.0% and a desirable discharge capacity of 176mAhg−1 at 0.1°C between 1.0 and 2.5V (vs. Li/Li+). The discharge capacity at 10°C is as high as 116mAhg−1 with capacity retention of 95.7% over 100cycles. Therefore, this Li4Ti5O12 nanocluster material can be a superior and practical candidate for the anodes of high-power lithium-ion batteries.

Thermal perturbation nucleation and growth of silver molybdate nanoclusters by a dynamic template route

Silver molybdate (Ag2MoO4) nanoclusters were first prepared by a dynamic template route under 20 °C. The heat released from the polymerization of the acrylamide (AM) assisted templates induced high active sites to be generated on the surface of the crystal where more attracted nuclei were adsorbed on. The continuously formed nuclei assembled together and the nanoclusters were formed. The paper provided an explanation for the formation of the Ag2MoO4 nanoclusters through the research on reaction conditions; on the other hand, the comparison of photocatalytic performance and antibacterial properties between the Ag2MoO4 nanoclusters and the Ag2MoO4 crystals of other morphologies showed that the Ag2MoO4 nanoclusters had better photocatalytic and antibacterial activities, which was a preliminary perspective for the application of the nanocluster materials.

Polyoxotungstate nanoclusters supported on silica as an efficient solid-phase microextraction fiber of polycyclic aromatic hydrocarbons

A highly porous silica-supported tungstophosphoric acid (PW) nanocluster was prepared for use in solid-phase microextraction (SPME) of polycyclic aromatic hydrocarbons (PAHs). The PWs represent a class of discrete transition metal-oxide nanoclusters and their structures resemble discrete fragments of metal-oxide structures of definite size and shape. Transition metal-oxide nanoclusters display large structural diversity, and their monodisperse sizes can be tuned from several Angstroms up to 10 nm. The highly porous silica-supported tungstophosphoric acid nanocluster material is found to be capable of efficiently extracting PAHs from aqueous sample solutions. The nanomaterial was immobilized on a stainless steel wire for fabrication of the SPME fiber. Following thermal desorption, the PAHs were quantified by GC-MS. Analytical merits include limits of detection that range from 0.02 to 0.1 pg mL−1 and a dynamic range as wide as from 0.001 to 100 ng mL−1. Under optimum conditions, the repeatability for one fiber (n = 3), expressed as the relative standard deviation, is between 4.3 % and 8.6 %. The method is simple, rapid, and inexpensive. The thermal stability of the fiber and the high relative recovery make this method superior to conventional methods of extraction.

Thermally Robust Au99(SPh)42 Nanoclusters for Chemoselective Hydrogenation of Nitrobenzaldehyde Derivatives in Water

We report the synthesis and catalytic application of thermally robust gold nanoclusters formulated as Au99(SPh)42. The formula was determined by electrospray ionization and matrix-assisted laser desorption ionization mass spectrometry in conjunction with thermogravimetric analysis. The optical spectrum of Au99(SPh)42 nanoclusters shows absorption peaks at ~920 nm (1.35 eV), 730 nm (1.70 eV), 600 nm (2.07 eV), 490 nm (2.53 eV), and 400 nm (3.1 eV) in contrast to conventional gold nanoparticles, which exhibit a plasmon resonance band at 520 nm (for spherical particles). The ceria-supported Au99(SPh)42 nanoclusters were utilized as a catalyst for chemoselective hydrogenation of nitrobenzaldehyde to nitrobenzyl alcohol in water using H2 gas as the hydrogen source. The selective hydrogenation of the aldehyde group catalyzed by nanoclusters is a surprise because conventional nanogold catalysts instead give rise to the product resulting from reduction of the nitro group. The Au99(SPh)42/CeO2 catalyst gives high catalytic activity for a range of nitrobenzaldehyde derivatives and also shows excellent recyclability due to its thermal robustness. We further tested the size-dependent catalytic performance of Au25(SPh)18 and Au36(SPh)24 nanoclusters, and on the basis of their crystal structures we propose a molecular adsorption site for nitrobenzaldehyde. The nanocluster material is expected to find wide application in catalytic reactions.

Nanoscale electron tomography and atomic scale high-resolution electron microscopy of nanoparticles and nanoclusters: A short surveyNanoscale electron tomography and atomic scale high-resolution electron microscopy of nanoparticles and nanoclusters: A short surveyretain-->

The outstanding merits of scanning transmission electron tomography as a technique for the investigation of the internal structure and morphology of nanoparticle and nanocluster materials are summarized with the aid of numerous typical illustrations. Reference is made also to the significant advances that have arisen in probing ultrastructural characteristics of nanoscale solids using aberration-corrected (AC) electron microscopy (EM). Information of a unique kind may be retrieved by combining the imaging and analytical power of ACEM.

Facile Synthesis of Highly Luminescent Mn-Doped ZnS Nanocrystals

Manganese-doped zinc sulfide quantum dots (Mn:ZnS d-dots) with high optical quality, pure dopant emission of 55-65% photoluminescence quantum yield, were synthesized in octadecene media with generic starting materials, namely, zinc (manganese) carboxylic acid salts, S powder, and dodecanethiol (DDT) based on a "nucleation doping" strategy. The optical properties and structure of the obtained Mn:ZnS d-dots have been characterized by UV-vis, photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). The resulting nearly monodisperse d-dots were found to be of spherical shape with a zinc-blende crystal structure. The influences of various experimental variables, including the reaction temperature for the MnS core nanocluster and ZnS host material, the amount of octadecene (ODE)-S, DDT, as well as Zn/Mn ratio have been systematically investigated. The use of DDT as capping ligand ensured the reproducible access to a stable small-sized MnS core. This paves the way for reproducibly obtaining highly luminescent d-dots. Programmed overcoating temperature for growth of ZnS shell was employed to realize balanced diffusion of the Mn ions in the d-dots.

Hopping Conductivity Spectroscopy of Carbon Nanocluster Materials

Procedure of the hopping conductivity ρ∼exp[(T 0/T)α] and magnetoresistance data analysis, which takes into account spin‐polarization contribution and allows finding correct parameters of the localized states, is suggested. This general approach was checked for the nanocluster material synthesized under high (up to 8 GPa) pressure of carbon SWNT mat containing 5% Ni. Experiments for the temperature/field domain 1.8–300 K/70 kOe have confirmed theoretical results, including universal magnetoresistance scaling ln[ρ(H)/ρ(0)] = (T 0/T)α F(H/T). It is found that the interaction with magnetic impurities renormalizes the electron magnetic moment: μ≈0.7μB. In conclusion, a possible way of creation of the carbon nanocluster material with colossal magnetoresistance is suggested.