Ultrathin Hexagonal Hybrid Nanosheets Synthesized by Graphene Oxide‐Assisted Exfoliation of β‐Co(OH)2 Mesocrystals |
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Authors: | Dr Suzi Deng Dr Christie Thomas?Cherian Xiao li Liu Hui Ru Tan Li Hsia Yeo Dr Xiaojiang Yu Prof Andrivo Rusydi Prof B V R Chowdari Prof Hai Ming Fan Prof Chorng Haur Sow |
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Institution: | 1. Department of Physics, National University of Singapore, 2 Science Drive 3 117542 (Singapore);2. Shaanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering, Northwest University, Xi'an, Shaanxi 710069 (P.R. China);3. Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link 117602 (Singapore);4. Department of Physics, NUSSNI‐NanoCore and Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link 117603 (Singapore) |
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Abstract: | In the present study, we report the synthesis of a high‐quality, single‐crystal hexagonal β‐Co(OH)2 nanosheet, exhibiting a thickness down to ten atomic layers and an aspect ratio exceeding 900, by using graphene oxide (GO) as an exfoliant of β‐Co(OH)2 nanoflowers. Unlike conventional approaches using ionic precursors in which morphological control is realized by structure‐directing molecules, the β‐Co(OH)2 flower‐like superstructures were first grown by a nanoparticle‐mediated crystallization process, which results in large 3D superstructure consisting of ultrathin nanosheets interspaced by polydimethoxyaniline (PDMA). Thereafter, β‐Co(OH)2 nanoflowers were chemically exfoliated by surface‐active GO under hydrothermal conditions into unilamellar single‐crystal nanosheets. In this reaction, GO acts as a two‐dimensional (2D) amphiphile to facilitate the exfoliation process through tailored interactions between organic and inorganic molecules. Meanwhile, the on‐site conjugation of GO and Co(OH)2 promotes the thermodynamic stability of freestanding ultrathin nanosheets and restrains further growth through Oswald ripening. The unique 2D structure combined with functionalities of the hybrid ultrathin Co(OH)2 nanosheets on rGO resulted in a remarkably enhanced lithium‐ion storage performance as anode materials, maintaining a reversible capacity of 860 mA h g?1 for as many as 30 cycles. Since mesocrystals are ubiquitous and rich in morphological diversity, the strategy of the GO‐assisted exfoliation of mesocrystals developed here provides an opportunity for the synthesis of new functional nanostructures that could bear importance in clean renewable energy, catalysis, photoelectronics, and photonics. |
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Keywords: | cobalt graphene lithium nanostructures X‐ray absorption spectroscopy |
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