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Metallic Nanomaterials (Part A) || 5. Synthesis and characterization of size-controlled atomically precise gold clusters
摘要： In this article, synthetic strategies and characterization methodologies of atomically precise gold clusters have been summarized. The typical and effective synthetic strategies including a systematic “size-focusing” methodology has been developed for attaining atomically precise gold clusters with size control. Another universal synthetic methodology is ligand exchange-induced size/structure transformation (LEIST) based on from one stable size to another. These two methodologies have largely expanded the “universe” of atomically precise gold clusters. Elite of typical synthetic case studies of ligand protected gold clusters are presented. Important characterization techniques of these atomically precise gold clusters also are included. The identification and characterization of gold clusters have been achieved in terms of nuclearity (size), molecular formulation, and geometrical structures by the combination of these techniques. The determination of gold cluster structure based on single crystals is of paramount importance in understanding the relationship of structure–property. The criterion and selection of these typical gold clusters are all “strictly” atomically precise that all have been determined ubiquitously by single crystal diffraction. These related crystallographic data are retrieved from Cambridge Crystallographic Data Centre (CCDC) up to 30th November 2017. Meanwhile, the cutting edge and other important characterization methodologies including electron diffraction (ED), extended X-ray absorption fine structure (EXFAS), and synchrotron sources are briefly reviewed. The new techniques hold the promise of pushing the limits of crystallization of gold clusters. This article is not just an exhaustive and up to date review, generally summarized synthetic strategies, but also a practical guide regarding gold cluster synthesis. We called it a “Cookbook” of ligand protected gold clusters, including synthetic recipes and characterization details.
关键词： alkyne,ligand exchange-induced size/structure transformation,phosphine,“size-focusing” methodology,size-controlled synthesis,thiolate,gold cluster
更新于2025-09-23 15:19:57
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Synthesis and radiation grafting modification of hydroxyl controlled AM/HEMA polymer microspheres
摘要： The, smooth-faced, highly cross-linked, hydroxyl controlled, micrometer-sized polymer micro-spheres of acrylamide (AM) and 2-hydroxyethyl methacrylate (HEMA) were prepared by reverse suspension polymerization. The polymerization parameters showed considerable influence on the morphologies and dispersion of the polymer particles, such as the stirring rate, polymerization temperature, monomer loading, initiator concentration, and crosslinking agent concentration, which makes it flexible to control the hydroxyl number of AM/HEMA microspheres by controlling polymerization conditions. Subsequently, the polymer particles was radiated with 60Co c-rays(dose rate: 4.0 kGy/h) in pure oxygen environment for 24 h, as a result, free radicals are generated on the surface of the polymer microspheres. Afterward, AM was allowed to be graft-polymerized on microspheres AM/HEMA in the manner of “grafting onto,” resulting in the grafted microspheres PAM–AM/HEMA. This work provides optimized parameters to fabricate micron-sized AM/HEMA microspheres, and further expands the functionalization of AM/HEMA microspheres and its application fields.
关键词： polymer microspheres,graft-modification,hydroxyl controlled,Synthesis
更新于2025-09-23 15:19:57
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Temperature-controlled synthesis of hollow, porous gold nanoparticles with wide range light absorption
摘要： An easy synthesis method of hollow, porous gold nanoparticles (AuHP NPs) with controlled diameter and pores sizes and with a wide range of light absorbance (continuous between 500 and 900 nm) is presented together with the explanation of the nanoparticle formation mechanism. The NPs were investigated using transmission electron microscopy (TEM) combined with the selected area electron diffraction patterns, X-ray diffraction and ultraviolet–visible spectroscopy. TEM images showed that changing the synthesis temperature allows to obtain AuHP NPs with sizes from 35 ± 4 nm at 60 °C to 76 ± 8 nm at 90 °C. The effects of nanoscale porosity on the far- and near-field optical properties of the nanoparticles, as well as on effective conversion of electromagnetic energy into thermal energy, were applied in simulated photothermal cancer therapy. The latter one was simulated by irradiation of two cancer cell lines SW480 and SW620 with lasers operating at 650 nm and 808 nm wavelengths. The mortality of cells after using the synthesized AuHP NPs as photosensitizers is between 20 and 50% and increases with the decrease in the diameter of the AuHP NPs. All these attractive properties of the AuHP NPs make them find application in many biomedical studies.
关键词： photothermal therapy,wide range light absorption,temperature-controlled synthesis,hollow porous gold nanoparticles
更新于2025-09-19 17:13:59
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Controlled synthesis and high photocatalytic properties of stannic oxide nanoflowers
摘要： The controllable stannic oxide nanoflowers had been synthesized by hydro-thermal method through changing synthesized reagent and temperature, in this paper. Then the structure and micromorphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Finally, the photocatalytic degradation ability of prepared products was studied by ultraviolet absorption method. The results showed that the prepared products were pure stannic oxide crystals with rutile structure, micromorphology of flower, good dispersibility, uniform size and strong photocatalytic degradation ability.
关键词： nanoflowers,hydro-thermal method,Stannic oxide,photocatalysis,controlled synthesis
更新于2025-09-16 10:30:52
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Carbon nanotube: Controlled synthesis determines its future; 碳纳米管: 可控制备决定未来;
摘要： Carbon nanotubes (CNTs) have received broad attention in the past decades due to their excellent physical and chemical properties and thus been regarded as a powerful candidate for future star-materials. Although various CNT products and their related applications have been demonstrated recently, their performance can hardly meet the researchers’ expectations compared with their theoretical properties. The current predicament is caused by the immature synthesis method, including the basic science and the producing technology. As the synthesis with controlled structures determines its future, this review summarizes the progress on the basic research and industrialization of CNTs in the past decades, including the fine structure control, aggregation status design and scale-up production, and further points out the way for the future development of CNTs combining with specific applications.
关键词： applications,carbon nanotubes,scale-up synthesis,structure-controlled synthesis
更新于2025-09-11 14:15:04
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Shape-controlled synthesis of golf-like, star-like, urchin-like and flower-like SrTiO3 for highly efficient photocatalytic degradation and H2 production
摘要： As a typical perovskite-type metal oxide, SrTiO3 has emerged as a prospective candidate for many fields. However, the synthesis of SrTiO3 with controlled morphology, high surface area, and enhanced photocatalytic activity are still lacking. Herein, a series of porous SrTiO3 with well-controlled morphologies including assembled nanoparticles (ANPs), golf-like particles (GLPs), star-like microspheres (SLMs), urchin-like microspheres (ULMs), and flower-like microspheres (FLMs) were successfully prepared via an ethylene glycol-water mixed solvothermal route. The ratio of VEG/VH2O play an important role in the shape-evolution during the solvothermal reaction. A comparative study of photocatalytic H2 production and photodegradation was performed, and a possible photocatalysis mechanism of SrTiO3 has been proposed. Significantly, the ULMs and FLMs photocatalysts of SrTiO3 with optimized low Pt loading amount (0.075wt.%) exhibited outstanding H2 production rates (8.21 and 7.29 mmol·g-1·h-1) due to its unique structure of high-surface area and defect-rich surface. The facile and shape-controlled synthesis of varied SrTiO3 structures is believed to be useful for the design and application of perovskite.
关键词： Mesoporous SrTiO3,Oxygen vacancy,Photocatalysis,Controlled-synthesis,Morphology evolution
更新于2025-09-11 14:15:04
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Low temperature phase-controlled synthesis of titanium di- and tri-sulfide by atomic layer deposition
摘要： Phase-controlled synthesis of two-dimensional (2D) transition metal chalcogenides (TMCs) at low temperature with a precise thickness control has to date been rarely reported. Here, we report on a process for the phase-controlled synthesis of TiS2 (metallic) and TiS3 (semiconducting) nano-layers by atomic layer deposition (ALD) with precise thickness control. The phase-control has been obtained by carefully tuning the deposition temperature and co-reactant composition during ALD. In all cases, characteristic self-limiting ALD growth behavior with a growth per cycle (GPC) of ~0.16 nm per cycle was observed. TiS2 was prepared at 100 °C using H2S gas as co-reactant, and was also observed using H2S plasma as co-reactant at growth temperatures between 150 and 200 °C. TiS3 was only synthesized at 100 °C using H2S plasma as co-reactant. The S2 species in the H2S plasma, as observed by optical emission spectroscopy, has been speculated to lead to the formation of the TiS3 phase at low temperature. The control between synthesis of TiS2 and TiS3 was elucidated by Raman spectroscopy, X-ray photoelectron spectroscopy, high-resolution electron microscopy, and Rutherford back scattering studies. Electrical transport measurements showed the low resistive nature of ALD grown 2D-TiS2 (1T-phase). Post-deposition annealing of the TiS3 layers at 400 °C in a sulfur-rich atmosphere improved the crystallinity of the film and yielded photoluminescence at ~0.9 eV, indicating the semiconducting (direct bandgap) nature of TiS3. The current study opens up a new ALD-based synthesis route for controlled, scalable growth of transition metal di- and tri-chalcogenides at low temperatures.
关键词： phase-controlled synthesis,low temperature,titanium sulfide,transition metal chalcogenides,atomic layer deposition
更新于2025-09-11 14:15:04