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The controllable packing of functional nanoparticles (NPs) into crystalline lattices is of interest in the development of NP-based materials. Here we demonstrate that the size, morphology and symmetry of such supercrystals can be tailored by adjusting the surface dynamics of their constituent NPs. In the presence of excess tetraethylammonium cations, atomically precise [Au

As a rapidly developing additive manufacturing technology, fused deposition modeling (FDM) has become widespread in many industry fields. It can fabricate complicated geometries using filament of thermoplastic materials such as PP, polylactic acid, acrylonitrile butadiene styrene, etc. However, poor mechanical properties of raw materials limit their application. Poly-ether-ether-ketone is a type of special engineering plastic with high performance, which could be further reinforced by adding carbon fibers (CFs). During FDM process, the mechanical properties of printed parts are largely subject to careful selection of process parameters. To improve the mechanical properties of PEEK and CF/PEEK 3D-printed parts, the effects of various process parameters including building orientation, raster angle, nozzle temperature, platform temperature, ambient temperature, printing speed, layer thickness, infill density, and number of printed parts on mechanical properties were investigated. The tensile fracture interfaces of printed parts were observed by scanning electron microscope (SEM) to explain the influence mechanism of process parameters. In the single factor experiments, flat and on-edge specimens show the best tensile and flexural strength, respectively; the specimens with raster angle ±45° and 0° show the best tensile and flexural strength, respectively. When the nozzle temperature at 500°C, platform temperature at 200°C, ambient temperature at 150°C, printing speed is 20 mm/s, layer thickness is 0.2 mm, and infill density is 100%, the printed parts exhibit the best mechanical properties.

Au(I)-thiolate complexes are a new class of aggregation-induced emission (AIE) material. Here we demonstrate a new aggregation strategy of water-soluble Au(I)-thiolate complexes induced by cationic polymers at optimized pH values. The generated AIE shows longer wavelengths than the emission induced by other methods.

Derivatization is the fine chemistry that can produce chemical compounds from similar precursors and has been widely used in the field of organic synthesis to achieve diversification of molecular properties and functionalities. Ligand-protected metal nanoclusters (NCs) are metallic molecules with a definite molecular formula, well-defined molecular structure, and molecular-like physical and chemical properties. Unlike organic compounds, which have almost infinite species, until now only hundreds of metal NC species have been discovered, and only a few of them have been structurally resolved. Therefore, the diversification of NC species and functions is highly desirable in nanoscience and nanochemistry. As an efficient approach for generating a library of compounds from a given precursor, derivatization chemistry is not only applicable in producing new organic compounds but also a promising strategy for generating new metal NC species with intriguing properties and functions. The key to the derivatization of metal NCs is to design an efficient derivatization reaction suitable for metal NCs and spontaneously realize the customization of this special macromolecule (metallic molecule) at the atomic and molecular level.In this Account, we use the flagship thiolate-protected NC Au25SR18 (SR denotes a thiolate ligand) as a model to illustrate the derivatization chemistry of metal NCs. In the past 3 years we have developed various derivatization reactions of Au25SR18, including isomerization, redox, ligand addition, alloying, and self-assembly reactions. We discuss the mechanisms that govern these reactions to realize precise customization of the NC structure, size, surface, composition, and interactions. It is particularly noteworthy that advanced techniques such as real-time electrospray ionization mass spectrometry and NMR spectroscopy enable us to have an atomic- and molecular-level understanding of the reaction mechanisms, which will further promote our efforts to design derivatization reactions for metal NCs. Through these delicate derivatization reactions, we can produce Au25SR18 derivatives with new physical, chemical, and biological properties, including electronic structures, photoluminescence, surface reactivity, and antimicrobial properties. Finally, we provide our perspectives on the opportunities and challenges of metal NC derivatization.The derivatization chemistry of metal NCs can not only diversify the properties and functions of metal NCs but also help us understand the structure-property relationship and design principles of metal nanomaterials, which will help advance the research frontier of nanoscience toward atomic precision.

Most inorganic nanoparticles are directly surface-terminated (and -stabilized) by protecting ligands, which could greatly affect the atomic packing and physical/chemical properties of their inorganic cores. Here, we show that the intermolecular interactions between the adsorbed molecules and surface ligands can also affect the core structure of inorganic nanoparticles. Through the coupling/decoupling of cationic surfactants (cetyltrimethylammonium cations, CTA+) and anionic surface ligands (para-mercaptobenzoic acid, p-MBA) in the aqueous phase, we have achieved a reversible transformation between two isomers of [Au25(p-MBA)18]− nanoclusters. The interconversion process between the two isomers shows the characteristics of a reversible nanocluster isomerization process, with a measured forward and backward activation barrier of 1.16 and 1.17 eV, respectively. One of the isomers has the structure similar to the single-crystal data of [Au25(SR)18]− known since 2008. The other isomer features a distinctly different optical absorption spectrum and color change (i.e., reddish brown to dark green) in the solution phase, and its structure is identified to be the one recently predicted and observed in gas phase through density functional theory (DFT) calculations. The two isomers are topologically connected via a simple rotation of the gold core without breaking any Au-S bonds at the metal-ligand interface. Molecular dynamics simulations suggest that the adsorbed CTA+ cations would interact with the p-MBA layer through the CH∙∙∙π interaction and stabilize the more open ligand shell of the new isomer in the forward isomerization process. Interestingly, this principle can also be extended to organic phases by using organo-soluble cations to stimulate the surface interactions. Our research proposes a new approach to control the structure of inorganic nanoparticles, which helps to customize their electronic and optical properties in the solution phase without changing their surface ligands.

L-Lactide is an intermediate for the industrial production of polylactic acid (PLA). The chemical and optical purities of lactide determine the quality of the prepared PLA. It is of great challenge to synthesize L-lactide efficiently with high chemical and optical purities under the conditions applicable for industrial production. With the national plastic reduction order issued, developing biodegradable materials such as PLA has gradually become a hot topic, and the production of upstream lactide is the key technique for the whole industrial chain. This mini-review aims to summarize typical works on the related synthetic technology development in recent years.

Increasing surface charge is a commonly used and efficient strategy to improve the stability of colloidal nanoparticles in solution, but the use of this strategy in metal nanoclusters (NCs) has not...

With the development of the chemical industry, more pollutants are produced in the environment, some of which are difficult to degrade by traditional biological treatment methods. Catalysis can dir...

Two novel low melting pointing metals (LMPMs), Bi-21In-18Pb-12Sn alloy and Ga-13.5Sn alloy as phase change materials (PCMs), were firstly proposed to work for thermal management in aerospace applications. Their phase change characteristics and thermal stability were investigated in comparison with that of conventional paraffin PCMs (i.e. C26H58 and C17H36). The results indicate that the latent heat per unit volume in the LMPMs is higher than that of the paraffin PCMs, leading to much better thermal capacity of the former, and this can effectively reduce the volume proportion of LMPMs in use. LMPMs exhibit excellent thermal conductivity compared with the paraffin PCMs, and this contributes to rapid absorption of the heat released by the temperature-controlled target, and consequently the temperature of the target could remain stable near the phase change temperature. Besides, the Al2O3 coating by the spraying method could act as effective corrosion inhibitor in protecting Al alloy container used for electronic packaging from the liquid Ga-Sn alloy. The temperature control characteristic and temperature gradient of LMPMs consequently could suit the applied requirement of spacecraft device operated in vacuum condition. Therefore, low melting point metals with better thermal conductivity and stability would be promising candidates for PCMs applied in the field of aerospace.

Herein we wish to propose the concept of “element-transfer reaction”, which may afford the access to elemental compounds by transferring certain elements from easily available resources efficiently, concisely and precisely. A good element-transfer reaction with industrial application potential shall not generate waste and is performed under energy-saving and environment-friendly conditions. During the past decade, we have developed a series of methods for the synthesis of fluorine- and selenium-containing compounds via the fluorine- and selenium-transfer reactions, while the redox reactions were considered to be the oxygen- and hydrogen-transfer reactions as well and were also widely studied by our group for producing the high-value-added fine chemicals. Some of these technologies have been successfully industrialized. This review summarizes our staged research results on fluorine-, oxygen-, hydrogen- and selenium-transfer reactions and makes a prospect on the developing trend in the field.

Catalytic oxidation is an important reaction in the fine chemical industry, environment, and energy. In the past few decades, many kinds of catalysts have been produced with promising catalytic performance for oxidation reactions; however, the understanding of the mechanisms is still insufficient due to the complexity of the composition and structure of conventional catalysts. In the past several years, the community has tried to address this problem by using ligand-protected atomically precise gold nanoclusters as model catalysts. Ligand-protected gold nanoclusters possess well-defined molecular formulas and structures, and they could serve as ideal model catalysts to understand the correlations between the composition/structure and the catalytic properties at the atomic level. This feature article provides a systematic overview of the related oxidation reactions and the understanding of the mechanisms based on atomically precise gold nanoclusters.

Plasmonic imaging has exhibited superiority in label-free and fast detection to single nanoparticles due to its high sensitivity and high temporal resolution, which plays an important role in environmental monitoring and biomedical research. As containing plenty of information associated with particle features, plasmonic imaging has been used for identifying the particle sizes, shapes, and permittivity. Yet, the effects of the nanoparticle features on plasmonic imaging are not investigated, which hinders the in-depth understanding to plasmonic imaging and its applications in particle identification. In this work, we analyzed five types of nanoparticles, including polystyrene (PS), Au, silicon nanospheres as well as PS and Ag nanowires. We illustrated the effects of nanoparticle sizes, shapes, and permittivity on spatial resolution, imaging contrast, and interference fringes. We found that nanoparticle sizes and permittivity influenced the imaging contrast. Via introducing size parameter relevant to interference fringes, the connection between particle shape and reduction rate of size parameter is built, and the effects of particle shapes on the interference patterns are revealed. Our research provides a basis for improving the plasmonic imaging and presents guidance for applications on particle identification in nano-detection, biosensor, and environmental monitoring.

Alloy nanoparticles represent one of the most important metal materials, finding increasing applications in diverse fields of catalysis, biomedicine, and nano-optics. However, the structural evolution of bimetallic nanoparticles in their full composition spectrum has been rarely explored at the molecular and atomic levels, imparting inherent difficulties to establish a reliable structure-property relationship in practical applications. Here, through an inter-particle reaction between [Au

Low selectivity and poor activity of photocatalytic CO

The interactions of materials with light determine their applications in various fields. In the past decade, ultrasmall metal nanoclusters (NCs) have emerged as a promising class of optical materials due to their unique molecular-like properties. Herein, the basic principles of optical absorption and photoluminescence of metal NCs, their interactions with polarized light, and light-induced chemical reactions, are discussed, highlighting the roles of the core and protecting ligands/motifs of metal NCs in their interactions with light. The metal core and protecting ligands/motifs determine the electronic structures of metal NCs, which are closely related to their optical properties. In addition, the protecting ligands/motifs of metal NCs contribute to their photoluminescence and chiral origin, further promoting the interactions of metal NCs with light through various pathways. The fundamentals of light-NC interactions provide guidance for the design of metal NCs in optical applications, which are discussed in the second part. In the last section, some strategies are proposed to further understand light-NC interactions, highlighting the challenges and opportunities. It is hoped that this work will stimulate more research on the optical properties of metal NCs and their applications in various fields.

A novel method to synthesize the important lithium-ion battery electrolyte LiPF6 was developed and successfully applied in industrial-level production. In comparison with the conventional synthetic...

Due to high sensitivity and temporal resolution, surface plasmon resonance microscope (SPRM) has been widely used in biological analysis. In this review, we briefly introduced the principle and setup of SPRM. Applications in label-free biological analysis are also indicated, including fast detection to single cells, exosomes, viruses, and molecules, as well as their dynamic behaviors. The limitations of SPRM are also depicted. The methods to improve the focus drift and low spatial resolution are illustrated. Two newly-developed microscopy techniques based on SPRM, i.e. plasmonic scattering microscope and electrochemical impedance microscope, are also described. Finally, a summary of SPRM technique and a bright future outlook is presented.

Ever-harsher service environments in the future will call for systematic studies on service behaviors of high-entropy alloys (HEAs) under multi-field coupling. Instead of focusing solely on service behaviors under conventional conditions, the promoted serration behavior of Al0.1CoCrFeNi HEA, commonly known as Portevin-Le Chatelier (PLC) effect, under coupled electron-heat field was quantitatively analyzed in terms of several characteristic parameters in this work. The obvious PLC phenomenon with severe serration can boost the decrease of tensile strength and elongation in the service environment of coupled electron-heat. Our results indicate that this macroscopic serrated behavior can be rationalized by defect-level microstructural interaction, namely the enhanced repetitive pinning and de-pinning effect of solute atoms on mobile dislocations, according to the mechanism of dynamic strain aging. This was proved by the increased kinking and bowing morphologies of dislocations, as well as abundant stacking faults under coupled electron-heat field.

Summary Sub-stoichiometric reactions are powerful tools for mechanistic analyses because they can stabilize key intermediates in chemical reactions. Here, we develop a multiple-step, sub-stoichiometric reduction platform that can precisely dope required electrons to synthesize atomically precise gold nanoclusters (Au NCs). Only a sub-stoichiometric amount of NaBH4 (equivalent to doping one valence electron into Au NCs) is introduced in each step. In 8 successive steps, we identify a series of stable intermediates whose relative abundance suggests a different growth pathway from previous reports. In addition, detailed analysis of 120 real-time mass spectra during the formation process reveals three meta-stable species. Moreover, the platform also sheds light on the structural evolution of Au NCs during the growth process. This method provides a platform for studying the molecular- and atomic-level evolution of metal NCs (in both size and structure), revealing the reaction dynamics of NC intermediates toward the formation of atomically precise metal NCs.

With the continuous development of ultraviolet technology, the working band of UV detector is more controllable and optional, and the sensitivity has been greatly improved, so it has been widely used in ultraviolet camera, flame detection, welding detection and other fields with its unique advantages, it is of great significance to study the performance of ultraviolet detector parts. In this paper, we designed a set of evaluation and testing devices for detecting the signal-to-noise ratio, resolution, dynamic range and other parameters of ultraviolet ICCD (intensified charge-coupled device) detector after carrying out theoretical evaluation of ultraviolet detection and imaging photoelectric system and studying its related testing technology. In this paper, firstly we analysed the definition and the testing principle of the ultraviolet ICCD detector’s relevant parameters, such as signal-to-noise ratio, resolution, dynamic range, and designed the relevant algorithm model on the basis of that, then designed the supporting related hardware such as: Uniform light source system, test target, dark box, video processing acquisition system, etc. Secondly, based on LabVIEW platform, the software of related data acquisition and analysis is developed, and the video real-time display is realized, and finally the test experiment of signal-to-noise ratio, resolution and dynamic range is carried out to evaluate the performance of UV ICCD detector.

GaAs material has excellent photoelectric properties and is the most sensitive vacuum semiconductor material in the visible light band. GaAs photocathode has become the core component of low-light-level night vision device and been widely used in the field of low-light-level night vision. We systematically analyzed the structural characteristics of the low-light image intensifier and defined the boundary conditions of GaAs electron emission. It provided calculation basis for further analysis of the photoelectric effect of GaAs photocathode. We established GaAs crystal model on first-principle, calculated the energy band structure, and analyzed the mechanism of surface electrons escaping. After photon energy transferring to the electronic, electrons were excited and went out of its orbit, becoming free electrons and gaining initial kinetic energy. According to the experience, we assumed the collision energy loss rate after free electron diffusion process, and calculated number of electron collision in crystal model and displacement distance. Linear displacement distance is electron diffusion length. The initial kinetic energy of electrons excited by GaAs material depends on the energy of incident photons, as well as on the cathode's own temperature. We analyzed the relationship between the electron diffusion length of the material and the temperature. The electron emission characteristics of GaAs material were summarized, which provided technical support for the subsequent process research of this cathode material. GaAs low light image intensifier is made of the following parts: photocathode、 MCP、 screen and high voltage power. Using the elastic collision model, we calculated the energy of the photon transported to the electron transfer. Assuming the collision energy loss rate of electronic diffusion is 20% every time, free electrons crash until photon energy losses. The collision frequency and the moving distance are GaAs material properties. We analyzed the relationship between the temperature and electron diffusion length of GaAs in this paper.

Low selectivity and poor activity of photocatalytic CO2 reduction process are usually limiting factors for its applicability. Herein, a hierarchical electron harvesting system is designed on CoNiP hollow nano-millefeuille (CoNiP NH), which enables the charge enrichment on CoNi dual active sites and selective conversion of CO2 to CH4 . The CoNiP serves as an electron harvester and photonic "black hole" accelerating the kinetics for CO2 -catalyzed reactions. Moreover, the dual sites form from highly stable CoONiC intermediates, which thermodynamically not only lower the reaction energy barrier but also transform the reaction pathways, thus enabling the highly selective generation of CH4 from CO2 . As an outcome, the CoNiP NH/black phosphorus with dual sites leads to a tremendously improved photocatalytic CH4 generation with a selectivity of 86.6% and an impressive activity of 38.7 µmol g-1 h-1 .

Aurophilic interactions (AuI ⋅⋅⋅AuI ) are crucial in directing the supramolecular self-assembly of many gold(I) compounds; however, this intriguing chemistry has been rarely explored for the self-assembly of nanoscale building blocks. Herein, we report on studies on aurophilic interactions in the structure-directed self-assembly of ultrasmall gold nanoparticles or nanoclusters (NCs, 2) staples accompanied by structure modification of the intrinsic Au13 kernel. Such motif reconstruction increases the content of AuI species in the protecting shell of Au NCs, providing the structural basis for directed aurophilic interactions, which promote the self-assembly of Au NCs into well-defined nanoribbons in solution. More interestingly, the compact structure and effective aurophilic interactions in the nanoribbons significantly enhance the luminescence intensity of Au NCs with an absolute quantum yield of 6.2 % at room temperature.

Synthesizing nanomaterials with anisotropic architectures, especially two-dimensional (2D) nanosheets (NSs), is a key focus of materials science research. Metal sulfide nanosheets (MSNSs) are typically obtained involving exfoliation of bulk metal sulfides with layered structures. The synthesis of NSs of intrinsically non-layered metal sulfides has received relatively less attention. Metal alkanethiolates with lamellar structures are now shown to serve as effective scaffolds for constructing NSs. A novel photochemical step was employed to transform 2D metal thiolates into MSNSs. By this strategy the 2D nature of metal thiolate precursors was preserved in the final products, resulting in the successful synthesis of NSs of binary PbS, CdS, and Cu9 S5 , as well as ternary wurtzite CuInS2 , Cu2 SnS3 . Results encourage the wider utilization of photochemical strategies in the synthesis of anisotropic MSNSs.

Ultrasmall metal nanoparticles (NPs) with a well-defined composition and structure, the so-called metal nanoclusters (NCs, usually smaller than 3 nm in size), represent the forefront subclass of functional NPs. In the past two decades, great progress has been made in precision synthesis, cluster structure resolving, and the discovery of the intriguing physical and chemical properties of metal NCs. Metal NCs with unique electronic structure and atomic precision have broad prospects in various applications. However, there is still a lack of systematic and in-depth discussion on the design rules of metal NCs for various applications and effective methods for engineering metal NCs to directly meet application requirements. In this review, we focus our discussions on the correlation between the applications and structures (and the physical and chemical properties) of metal NCs, highlighting the basic principles of structure- and property-oriented applications of metal NCs. This correlation will provide guidance for the design of metal NCs with the desirable properties to meet application needs. First, we introduce the physical and chemical properties of metal NCs, including discrete electronic structure, precise composition, and chirality, which are distinctly different from larger metal NPs (typically > 3 nm). Then, we discuss the efforts on controlled synthesis and modulation of metal NCs from the atomic to molecular level, followed by highlighting structural- and property-oriented applications. Finally, we put forward some ideas for future work of metal NCs for catalysis and biomedical applications.

The design of surface ligands is crucial for ligand-protected gold nanoclusters (Au NCs). Besides providing good protection for Au NCs, the surface ligands also play the following two important roles: i) as the outermost layer of Au NCs, the ligands will directly interact with the exterior environment (e.g., solvents, molecules and cells) influencing Au NCs in various applications; and ii) the interfacial chemistry between ligands and gold atoms can determine the structures, as well as the physical and chemical properties of Au NCs. A delicate ligand design in Au NCs (or other metal NCs) needs to consider the covalent bonds between ligands and gold atoms (e.g., gold-sulfur (Au-S) and gold-phosphorus (Au-P) bond), the physics forces between ligands (e.g., hydrophobic and van der Waals forces), and the ionic forces between the functional groups of ligands (e.g., carboxylic (COOH) and amine group (NH2 )); which form the underlying chemistry and discussion focus of this review article. Here, detailed discussions on the effects of surface ligands (e.g., thiolate, phosphine, and alkynyl ligands; or hydrophobic and hydrophilic ligands) on the synthesis, structures, and properties of Au NCs; highlighting the design principles in the surface engineering of Au NCs for diverse emerging applications, are provided.

Photoinduced syntheses offer significant advantages over conventional thermal strategies, including improved control over reaction kinetics and low synthesis temperatures, affording nanoparticles with nontrivial and thermodynamically unstable structures. However, the photoinduced syntheses of non-metallic nanocrystalline products (such as metal sulfides) have not yet been reported. Herein, we demonstrate the first photoinduced synthesis of ultrafine (sub-2 nm) Ag2S quantum dots (QDs) from Ag nanoparticles at 10 °C. By thorough investigation of the mechanism for the transformation, a fundamental link was established between the intrinsic structures of the molecular intermediates and the final Ag2S products. Our results confirm the viability of low-temperature photochemical approaches in metal sulfide synthesis, and demonstrate a new rule which could be followed in it.

Hydrophobic quaternary AgInZn7S9 nanorods with good visible-light response prepared via high-temperature pyrolysis method were transferred into aqueous solutions by inserting surfactants into their hydrophobic ligand layer for improved photocatalytic H2 production. Photocatalytic H2 evolution tests of AgInZn7S9 nanorods showed that the surfactants on their surfaces have a significant effect on their H2 evolution activities. Specifically, anionic surfactants can promote H2 evolution by enriching protons on the surface of AgInZn7S9 nanorods.

The effect of electric current on Portevin-Le Chatelier (PLC) effect of CoCrFeMnNi high-entropy alloy (HEA) was investigated. Compared with previous studies, PLC effects were firstly observed at much lower temperatures than 275 °C. Theoretical analysis based on the experimental results indicates that the electromigration effect and the increased concentration of vacancies induced by electric current can significantly improve the mobility of solute atoms in CoCrFeMnNi HEA. Together with the increased dislocation density, the enhanced mobility of solute atoms can facilitate the repeated locking and unlocking process of mobile dislocations by the solutes during plastic deformation process. Consequently, this leads to the promoted PLC effect at lower temperatures, which is also supported by TEM analysis and the estimated higher activation energy of 285.4 kJ mol−1 between 275 °C and 325 °C.

A copper(i) cysteine complex generated by mixing Cu(ii) ions with cysteine in aqueous solution greatly enhanced the activity of CdSe photocatalysts for H2 production in aqueous solution under visible light excitation. The complex can enhance the H2 evolution rate by as much as 150 times, by acting as an oxidation co-catalyst and increasing charge carrier lifetimes. The copper(i) cysteine complex can also be applied to enhance the H2 production performance of other semiconductor photocatalyst systems, thereby affording a new research direction in the development of co-catalysts for solar hydrogen production.

The synthesis of atomically precise thiolate-stabilized silver (Ag) nanoclusters is the subject of intense research interest, yet the formation mechanism of such nanoclusters remains obscure. Here, electrospray ionization mass spectrometry is successfully applied to monitor the reaction intermediates formed during the sodium-borohydride-reduction of silver 4-tert-butylbenzenethiolate (AgSPh-tBu). We demonstrate a unique evolution route to thiolate-stabilized Ag nanoclusters mediated by Ag-thiolate clusters. The Ag-thiolate clusters form in the initial stage of reduction contain tens of Ag atoms and similar number of ligands, and they are transformed into Ag17(SPh-tBu)123− and Ag44(SPh-tBu)304− nanoclusters in the later reduction process. The number of Ag atoms in the Ag-thiolate clusters determines the reaction path to each final nanocluster product. A similar mechanism is found when silver 2,4-dimethylbenzenethiolate (AgSPhMe2) is used as precursor. This mechanism differs markedly from the long-established bottom-up evolution process, providing valuable new insights into the synthesis of metal nanoclusters.