At the 2022 Beijing Winter Olympics, the concept of sustainable development impressed the world. This study is supported by the concept of ecological protection and conservation. The easily available plastic bottled Coca-Cola® was innovatively proposed as a low-cost solvent to greenly exfoliate bulk tungsten disulfide (WS 2 ). First, an overview of two-dimensional (2D) WS 2 was given, summarizing the related reports on its structures and synthesis. Taking into account the yield of 2D flakes, the optimal fabrication environment was figured out. The related characterizations of the cola-synthetic WS 2 were studied. This work opens up a new strategy for the inexpensive and green exfoliation of 2D crystals with a high yield.
Jian-nan Yin,Xin-ying Shi,Huan Zhou,Jing-jing Tang,Ya-ping Dai,Xiao-qin Bai
Fine calcium hypophosphite can be synthesized by sodium hypophosphite and calcium chloride via the replacement reaction, and sodium hypophosphite can be synthesized from phosphorus via the intermediate of Ca(H2PO2)2. Both processes involve the interactive quaternary system of (Ca2+ + Na+)//(Cl– + (H2PO2)− + H2O) and its subsystems. In this study, the (solid + liquid) phase diagrams of the (Ca(H2PO2)2 + H2O) binary system from freezing to boiling point at normal pressure, and (Ca(H2PO2)2 + CaCl2 + H2O), (Ca(H2PO2)2 + NaH2PO2 + H2O) ternary systems at 273.15 K were experimentally determined via the classical isothermal solubility equilibrium method. It was found that (1) one anhydrous salt of Ca(H2PO2)2 occurs in (Ca(H2PO2)2 + H2O) binary systems with temperatures ranging from freezing to boiling points, (2) two solid salts of Ca(H2PO2)2 and CaCl2·6H2O exist in the (Ca(H2PO2)2 + CaCl2 + H2O) system, and (3) Ca(H2PO2)2, NaH2PO2·H2O and one incompatible double salt of NaCa(H2PO2)3 exist in the (Ca(H2PO2)2 + NaH2PO2 + H2O) system, and NaCa(H2PO2)3 has very low solubility and occupies a large solid field in the ternary system.
Controlling the morphology of noble metal nanoparticles can be an effective way to produce nanomaterials with favourable properties. Herein, we report our study on the effects of diffusion rate and reaction kinetics on the morphology of a number of noble metal (Au, Ag, Pd, and Pt) nanoparticles. A glass reactor based on electrochemical reduction or photo-reduction has been designed to achieve control of diffusion and chemical reduction of the different noble metal precursors. The results show that the noble metal nanoparticles with flower-like, core–shell, or wheel-like morphologies could be obtained at a relatively high diffusion rate due to the presence of additional growth of metal precursors on the preformed metal nuclei, while at relatively low diffusion, the as-prepared noble metal nanoparticles are small and quasi-spherical due to the relatively fast reduction of metal precursors. The experimental observations are also confirmed qualitatively by kinetic Monte Carlo (kMC) simulations. Since diffusion and reaction kinetics are universal and key factors in the synthesis of nanomaterials, the findings in this work might provide an effective way to manipulate the morphology of nanomaterials for a given application.
Pei Zhang,Yanlong Wei,Ming Ou,Zhenzhu Huang,Shudong Lin,YuanYuan Tu,Jiwen Hu
The bromide-mediated polyol method has been widely used to synthesize ultrathin silver nanowires , however, the reason why the addition of bromide ions can reduce the diameter of silver nanowires is unclear. To elucidate this mechanism, we have conducted a series of experiments in which the amount of halide ions is kept constant while the ratio of Cl − to Br − ions is varied, to investigate how the halide ions influence the morphology of AgNWs. Based on these experiments and previous studies, we propose herein that the bromide ions fulfill three roles: (i) facilitating the formation of AgBr cubes as nucleation events, (ii) limiting the lateral growth of AgNWs and (iii) enabling the formation of more stable AgBr complexes. Our current study should be useful for enabling size-controlled synthesis of silver nanowires via the bromide-mediated polyol method.
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