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Ulyanov A, Stolbov D, Savilov S. Jellyfish-like few-layer graphene nanoflakes: high paramagnetic response alongside increased interlayer interaction. Z PHYS CHEM 2021. [DOI: 10.1515/zpch-2020-1784] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Jellyfish-like graphene nanoflakes (GNF), prepared by hydrocarbon pyrolysis, are studied with electron paramagnetic resonance (EPR) method. The results are supported by X-ray photoelectron spectroscopy (XPS) data. Oxidized (GNFox) and N-doped oxidized (N-GNFox) flakes exhibit an extremely high EPR response associated with a large interlayer interaction which is caused by the structure of nanoflakes and layer edges reached by oxygen. The GNFox and N-GNFox provide the localized and mobile paramagnetic centers which are silent in the pristine (GNF
p
) and N-doped (N-GNF) samples. The change in the relative intensity of the line corresponding to delocalized electrons is parallel with the number of radicals in the quaternary N-group. The environment of localized and mobile electrons is different. The results can be important in GNF synthesis and for explanation of their features in applications, especially, in devices with high sensitivity to weak electromagnetic field.
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Affiliation(s)
- Alexander Ulyanov
- Department of Chemistry , M. V. Lomonosov Moscow State University , Leninskie gori, 1 , Moscow 119991 , Russia
| | - Dmitrii Stolbov
- Department of Chemistry , M. V. Lomonosov Moscow State University , Leninskie gori, 1 , Moscow 119991 , Russia
| | - Serguei Savilov
- Department of Chemistry , M. V. Lomonosov Moscow State University , Leninskie gori, 1 , Moscow 119991 , Russia
- Russian Academy of Sciences , A. V. Topchiev Institute of Petrochemical Synthesis , 29, Leninsky pr., 29 , Moscow 119991 , Russia
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Choi DS, Kim C, Lim J, Cho SH, Lee GY, Lee HJ, Choi JW, Kim H, Kim ID, Kim SO. Ultrastable Graphene-Encapsulated 3 nm Nanoparticles by In Situ Chemical Vapor Deposition. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1805023. [PMID: 30318636 DOI: 10.1002/adma.201805023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/19/2018] [Indexed: 06/08/2023]
Abstract
Nanoscale materials offer enormous opportunities for catalysis, sensing, energy storage, and so on, along with their superior surface activity and extremely large surface area. Unfortunately, their strong reactivity causes severe degradation and oxidation even under ambient conditions and thereby deteriorates long-term usability. Here superlative stable graphene-encapsulated nanoparticles with a narrow diameter distribution prepared via in situ chemical vapor deposition (CVD) are presented. The judiciously designed CVD protocol generates 3 nm size metal and ceramic nanoparticles intimately encapsulated by few-layer graphene shells. Significantly, graphene-encapsulated Co3 O4 nanoparticles exhibit outstanding structural and functional integrity over 2000 cycles of lithiation/delithiation for Li-ion battery anode application, accompanied by 200% reversible volume change of the inner core particles. The insight obtained from this approach offers guidance for utilizing high-capacity electrode materials for Li-ion batteries. Furthermore, this in situ CVD synthesis is compatible with many different metal precursors and postsynthetic treatments, including oxidation, phosphidation, and sulfidation, and thus offers a versatile platform for reliable high-performance catalysis and energy storage/conversion with nanomaterials.
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Affiliation(s)
- Dong Sung Choi
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Chanhoon Kim
- Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Joonwon Lim
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Su-Ho Cho
- Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Gil Yong Lee
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Ho Jin Lee
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Jang Wook Choi
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea
| | - Heeyeon Kim
- Energy Materials Laboratory, KIER, Daejeon, 34129, Republic of Korea
| | - Il-Doo Kim
- Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Republic of Korea
| | - Sang Ouk Kim
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science and Engineering, KAIST, Daejeon, 34141, Republic of Korea
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Congratulations to Alexander Eychmüller. Z PHYS CHEM 2018. [DOI: 10.1515/zpch-2018-5004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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