Feedback Kinetics in Mechanochemistry: The Importance of Cohesive States

Hutchings, Benjamin P.; Crawford, Deborah E.; Gao, Lei; Hu, P.; James, Stuart L.

doi:10.1002/ange.201706723

Cited by 49 publications

(30 citation statements)

References 29 publications

(15 reference statements)

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“…and chemical steps (chemical reactions), both of which are important for the system to evolve toward a given product. 53 , 54 Despite numerous investigations, some of which include in situ measurements and/or innovative designs of the milling equipment, 54 − 59 many blind spots remain regarding both the physics and chemistry of mechanochemical reactions. This is even more true when common techniques like XRD are not informative, as observed here for the four p- and d-block oxides, as well as for the mixed SiO 2 /TiO 2 system.…”

Section: Results and Discussionmentioning

confidence: 99%

Direct ¹⁷O Isotopic Labeling of Oxides Using Mechanochemistry

et al. 2020

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While 17 O NMR is increasingly being used for elucidating the structure and reactivity of complex molecular and materials systems, much effort is still required for it to become a routine analytical technique. One of the main difficulties for its development comes from the very low natural abundance of 17 O (0.04%), which implies that isotopic labeling is generally needed prior to NMR analyses. However, 17 O-enrichment protocols are often unattractive in terms of cost, safety, and/or practicality, even for compounds as simple as metal oxides. Here, we demonstrate how mechanochemistry can be used in a highly efficient way for the direct 17 O isotopic labeling of a variety of s-, p-, and d-block oxides, which are of major interest for the preparation of functional ceramics and glasses: Li 2 O, CaO, Al 2 O 3 , SiO 2 , TiO 2 , and ZrO 2 . For each oxide, the enrichment step was performed under ambient conditions in less than 1 h and at low cost, which makes these synthetic approaches highly appealing in comparison to the existing literature. Using high-resolution solid-state 17 O NMR and dynamic nuclear polarization, atomic-level insight into the enrichment process is achieved, especially for titania and alumina. Indeed, it was possible to demonstrate that enriched oxygen sites are present not only at the surface but also within the oxide particles. Moreover, information on the actual reactions occurring during the milling step could be obtained by 17 O NMR, in terms of both their kinetics and the nature of the reactive species. Finally, it was demonstrated how high-resolution 17 O NMR can be used for studying the reactivity at the interfaces between different oxide particles during ball-milling, especially in cases when X-ray diffraction techniques are uninformative. More generally, such investigations will be useful not only for producing 17 O-enriched precursors efficiently but also for understanding better mechanisms of mechanochemical processes themselves.

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Section: Results and Discussionmentioning

confidence: 99%

Direct ¹⁷O Isotopic Labeling of Oxides Using Mechanochemistry

et al. 2020

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“…Mechanochemical reactions are indeed far from trivial, as they involve both physical steps (mixing of reagents, particle size reduction, creation of reactive surfaces, diffusion of atoms/molecules at the interfaces…) and chemical steps (chemical reactions), both of which are important for the system to evolve towards a given product. [53][54] Despite numerous investigations, some of which include in situ measurements and/or innovative designs of the milling equipment, [54][55][56][57][58][59] many blind spots remain regarding both the physics and chemistry of mechanochemical reactions. This is even more true when common techniques like X-ray diffraction are not informative, as observed here for the four p-and d-block oxides, as well as for the mixed SiO 2 /TiO 2 system.…”

Section: Atomic-level Insight Into Reactions Occurring During Ball-mimentioning

confidence: 99%

Direct 17O-Isotopic Labeling of Oxides Using Mechanochemistry

Chen¹,

Gaillard²,

Mentink-Vigier³

et al. 2019

Preprint

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While oxygen-17 NMR is increasingly being used for elucidating the structure and reactivity of complex molecular and materials systems, much effort is still required for it to become a routine analytical technique. One of the main difficulties for its development comes from the very low natural abundance of oxygen-17, which implies that isotopic labeling is generally needed prior to NMR analyses. However, 17O-enrichment protocols are often unattractive in terms of cost, safety, and/or practicality, even for compounds as simple as metal oxides. Here, we demonstrate how mechanochemistry can be used in a highly efficient way for the direct 17O-isotopic labeling of a variety of s-, p- and d-block oxides which are of major interest for the preparation of functional ceramics and glasses: Li2O, CaO, Al2O3, SiO2, TiO2, and ZrO2. For each oxide, the enrichment step was performed under ambient conditions in less than 1 hour and at low cost, which makes these synthetic approaches highly appealing in comparison to the existing literature. Using high-resolution 17O solid state NMR and Dynamic Nuclear Polarization, atomic-level insight into the enrichment process is achieved, especially for titania and alumina. Indeed, it was possible to demonstrate that enriched oxygen sites are present not only at the surface, but also within the oxide particles. Moreover, information on the actual reactions occurring during the milling step could be obtained by 17O NMR, both in terms of their kinetics and the nature of the reactive species. Finally, it was demonstrated how high resolution 17O NMR can be used for studying the reactivity at the interfaces between different oxide particles during ball-milling, especially in cases when X-ray diffraction techniques are uninformative. More generally, such investigations will be useful not only for producing 17O-enriched precursors efficiently, but also for understanding better mechanisms of mechanochemical processes themselves. <br>

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“…Mechanochemical synthesis is one of the fascinating synthetic approaches with notable simple, rapid, and reproducible properties . Besides, the method is also considered to overcome the problems related to the solution‐based chemistry processes .…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical Synthesis of γ‐Graphyne with Enhanced Lithium Storage Performance

Yang

et al. 2019

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γ‐Graphyne is a new nanostructured carbon material with large theoretical Li+ storage due to its unique large conjugate rings, which makes it a potential anode for high‐capacity lithium‐ion batteries (LIBs). In this work, γ‐graphyne‐based high‐capacity LIBs are demonstrated experimentally. γ‐Graphyne is synthesized through mechanochemical and calcination processes by using CaC2 and C6Br6. Brunauer–Emmett–Teller, atomic force microscopy, X‐ray photoelectron spectroscopy, solid‐state 13C NMR and Raman spectra are conducted to confirm its morphology and chemical structure. The sample presents 2D mesoporous structure and is exactly composed of sp and sp2‐hybridized carbon atoms as the γ‐graphyne structure. The electrode shows high Li+ storage (1104.5 mAh g−1 at 100 mA g−1) and rate capability (435.1 mAh g−1 at 5 A g−1). The capacity retention can be up to 948.6 (200 mA g−1 for 350 cycles) and 730.4 mAh g−1 (1 A g−1 for 600 cycles), respectively. These excellent electrochemical performances are ascribed to the mesoporous architecture, large conjugate rings, enlarged interplanar distance, and high structural integrity for fast Li+ diffusion and improved cycling stability in γ‐graphyne. This work provides an environmentally benign and cost‐effective mechanochemical method to synthesize γ‐graphyne and demonstrates its superior Li+ storage experimentally.

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Feedback Kinetics in Mechanochemistry: The Importance of Cohesive States

Cited by 49 publications

References 29 publications

Direct ¹⁷O Isotopic Labeling of Oxides Using Mechanochemistry

Direct ¹⁷O Isotopic Labeling of Oxides Using Mechanochemistry

Direct 17O-Isotopic Labeling of Oxides Using Mechanochemistry

Mechanochemical Synthesis of γ‐Graphyne with Enhanced Lithium Storage Performance

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Feedback Kinetics in Mechanochemistry: The Importance of Cohesive States

Cited by 49 publications

References 29 publications

Direct 17O Isotopic Labeling of Oxides Using Mechanochemistry

Direct 17O Isotopic Labeling of Oxides Using Mechanochemistry

Direct 17O-Isotopic Labeling of Oxides Using Mechanochemistry

Mechanochemical Synthesis of γ‐Graphyne with Enhanced Lithium Storage Performance

Contact Info

Product

Resources

About

Direct ¹⁷O Isotopic Labeling of Oxides Using Mechanochemistry

Direct ¹⁷O Isotopic Labeling of Oxides Using Mechanochemistry