Mechanochemical Synthesis of Fe-Based Nanocomposites and Their Application in the Catalytic Formation of Carbon Nanostructures

Author(s):  
B.H. Liu ◽  
J. Ding ◽  
Z.L. Dong ◽  
Zeng Yong Zhong ◽  
Jian Yi Lin ◽  
...  
2006 ◽  
Vol 111 ◽  
pp. 183-186 ◽  
Author(s):  
B.H. Liu ◽  
J. Ding ◽  
Z.L. Dong ◽  
Zeng Yong Zhong ◽  
Jian Yi Lin ◽  
...  

Mechanochemical process was employed to prepare Fe/MgO and Fe/NaCl nanocomposites. The carbon nanostructures (nanotubes and carbon-encapsulated Fe nanoparticles) were successfully synthesized using two nanocomposites as the catalyst. Our wok revealed that the morphology of Fe nanoparticles in the Fe/MgO nanocomposites depended on the distribution and particle size of iron oxides in the precursors. The size of Fe nanoparticles greatly affected their catalytic properties and the morphologies of carbon nanotubes. The successful carbon encapsulation of Fe nanoparticles was achieved by using the mechanochemically derived Fe/NaCl catalyst.


2020 ◽  
Author(s):  
Theodosios Famprikis ◽  
O. Ulas Kudu ◽  
James Dawson ◽  
Pieremanuele Canepa ◽  
François Fauth ◽  
...  

<div> <p>Fast-ion conductors are critical to the development of solid-state batteries. The effects of mechanochemical synthesis that lead to increased ionic conductivity in an archetypical sodium-ion conductor Na<sub>3</sub>PS<sub>4</sub> are not fully understood. We present here a comprehensive analysis based on diffraction (Bragg, pair distribution function), spectroscopy (impedance, Raman, NMR, INS) and <i>ab-initio</i> simulations aimed at elucidating the synthesis-property relationships in Na<sub>3</sub>PS<sub>4</sub>. We consolidate previously reported interpretations about the local structure of ball-milled samples, underlining the sodium disorder and showing that a local tetragonal framework more accurately describes the structure than the originally proposed cubic one. Through variable-pressure impedance spectroscopy measurements, we report for the first time the activation volume for Na<sup>+</sup> migration in Na<sub>3</sub>PS<sub>4</sub>, which is ~30% higher for the ball-milled samples. Moreover, we show that the effect of ball-milling on increasing the ionic conductivity of Na<sub>3</sub>PS<sub>4</sub> to ~10<sup>-4</sup> S/cm can be reproduced by applying external pressure on a sample from conventional high temperature ceramic synthesis. We conclude that the key effects of mechanochemical synthesis on the properties of solid electrolytes can be analyzed and understood in terms of pressure, strain and activation volume.</p> </div>


2018 ◽  
Author(s):  
Erik Leonhardt ◽  
Jeff M. Van Raden ◽  
David Miller ◽  
Lev N. Zakharov ◽  
Benjamin Aleman ◽  
...  

Extended carbon nanostructures, such as carbon nanotubes (CNTs), exhibit remarkable properties but are difficult to synthesize uniformly. Herein, we present a new class of carbon nanomaterials constructed via the bottom-up self-assembly of cylindrical, atomically-precise small molecules. Guided by supramolecular design principles and circle packing theory, we have designed and synthesized a fluorinated nanohoop that, in the solid-state, self-assembles into nanotube-like arrays with channel diameters of precisely 1.63 nm. A mild solution-casting technique is then used to construct vertical “forests” of these arrays on a highly-ordered pyrolytic graphite (HOPG) surface through epitaxial growth. Furthermore, we show that a basic property of nanohoops, fluorescence, is readily transferred to the bulk phase, implying that the properties of these materials can be directly altered via precise functionalization of their nanohoop building blocks. The strategy presented is expected to have broader applications in the development of new graphitic nanomaterials with π-rich cavities reminiscent of CNTs.


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