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Atomic Scale Evolution of Graphitic Shells Growth via Pyrolysis of Cobalt Phthalocyanine
Author(s) -
Zhang Xiaofang,
Yang Feng,
Tian Dongliang,
Zhao Haofei,
Wang Rongming,
Lau WoonMing
Publication year - 2020
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.202001112
Subject(s) - materials science , nanostructure , nanotechnology , cobalt , phthalocyanine , transmission electron microscopy , atomic units , pyrolysis , carbon fibers , chemical engineering , chemical physics , composite material , composite number , chemistry , metallurgy , physics , quantum mechanics , engineering
Nanostructured graphitic‐layer‐materials with precise control of the layer‐nanostructure, are known to surpass many benchmarks in electrical, optical, and mechanical properties. The development of such controlled synthesis is, however, stalled by the difficulty in tracking the exact growth mechanism and dynamics of the layer‐structure. Herein, the growth mechanism of onion‐like graphitic‐layer‐structures with an atomic precision is revealed by pyrolysis in an aberration‐corrected environmental transmission electron microscopy (ETEM). Specifically, the time‐evolution of cobalt phthalocyanine (CoPc), bearing better contact between carbon atoms and metamorphosizing a graphitization‐catalyst, at 850°C in an ETEM are tracked to an intriguing Co‐Co 3 C nanocore enveloped by several graphitic layers. The growth dynamics of this onion‐like graphitic shell comprises, rather unexpectedly, out‐diffusion of carbon atoms from the core to fuel the growth of new outermost shell‐layers, plus lateral/inwards and intrashell/intershell diffusion of carbon atoms to amend shell‐defects. Thus, unusual dynamics of seemingly contracting shell‐expansion and shell‐consolidation is revealed, with the surprising phenomenon of a decrease in the number of atomic shell‐layers in exchange for layer‐perfectness towards the end of the controlled synthesis. These results indicate pyrolysis of an organometallic compound in an ETEM is a paradigm for understanding and developing controlled synthesis of novel high‐quality graphitic‐layer‐materials.