Exfoliated graphene ligands stabilizing copper cations

Yamada, Yoshio; Miyauchi, Masato; Kim, Jungpil; Hirose-Takai, Kaori; Sato, Yuta; Suenaga, Kazu; Ohba, Tomonori; Sodesawa, Toshiaki; Sato, Satoshi

doi:10.1016/j.carbon.2011.03.056

Cited by 20 publications

(5 citation statements)

References 10 publications

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“…It is seen that the conversion of formic acid was very stable. This result is in accordance with the data of Yamada et al, 16 who reported that single Cu atoms and small clusters on N-doped graphene sheets are thermally stable until 773 K. Also, Kondo et al 36 compared the stability of monolayer Pt clusters on Ndoped and N-free graphite surfaces under conditions of the H 2 -D 2 exchange reaction and found a much better stability of Pt clusters on the N-doped graphite.…”

Section: Catalytic Studysupporting

confidence: 81%

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Copper on carbon materials: stabilization by nitrogen doping

et al. 2017

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The applicability of Cu/C catalysts is limited by sintering of Cu leading to deactivation in catalytic reactions.We show that the problem of sintering could be resolved by N-doping of the carbon support. Cu nanocatalysts with 1 at% of metal were synthesized by Cu acetate decomposition on N-free and Ndoped (5.7 at% N) mesoporous carbon supports as well as on thermally expanded graphite oxide.Catalytic properties of these samples were compared in hydrogen production from formic acid decomposition. The N-doping leads to a strong interaction of the Cu species with the support providing stabilization of Cu in the form of clusters of less than 5 nm in size and single Cu atoms, which were observed in a significant ratio by atomic resolution HAADF/STEM even after testing the catalyst under harsh conditions of the reaction at 600 K. The mean size of the obtained Cu clusters was by a factor of 7 smaller than that of the particles in the N-free catalyst. The N-doped Cu catalyst possessed good stability in the formic acid decomposition at 478 K for at least 7 h on-stream and a significantly higher catalytic activity than the N-free Cu catalysts. The nature of the strongly interacting Cu species was studied by XPS, XRD and other methods as well as by DFT calculations. The presence of single Cu atoms in the N-doped catalysts should be attributed to their strong coordination by pyridinic nitrogen atoms at the edge of the graphene sheets of the support. We believe that the N-doping of the carbon support will allow expanding the use of Cu/C materials for different applications avoiding sintering and deactivation.

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Section: Catalytic Studysupporting

confidence: 81%

“…15 However, at small concentrations of Cu (1 and 3 wt%), Yamada et al 16 have also shown that N-doping of exfoliated graphene leads to stabilization of atomically dispersed Cu. They proposed that this may take place because of the strong coordination of Cu 2+ ions by N-doped graphene sheets.…”

Section: Introductionmentioning

confidence: 99%

Copper on carbon materials: stabilization by nitrogen doping

et al. 2017

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“…Subnanometer vacancy defects in the basal plane of single-layer nanocarbon materials such as graphene and single-walled carbon nanotubes (SWCNTs) have been intensively studied because of a number of possible applications such as selective ion passage, water desalination, separation of gases, − impregnation of electrolytes, , and ligands to coordinate metal ions. , The most common methods to introduce vacancy defects on carbon materials are reactions with oxygen gas − ,, and ion bombardment followed by oxidation. , Oxygen gas is superior to ion bombardment in terms of the accessibility of oxygen gas from multiple directions and the availability of oxygen gas. Thus, reactions of carbon materials with oxygen gas are still preferred for mass production.…”

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confidence: 99%

Subnanometer Vacancy Defects Introduced on Graphene by Oxygen Gas

et al. 2014

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The basal plane of graphene has been known to be less reactive than the edges, but some studies observed vacancies in the basal plane after reaction with oxygen gas. Observation of these vacancies has typically been limited to nanometer-scale resolution using microscopic techniques. This work demonstrates the introduction and observation of subnanometer vacancies in the basal plane of graphene by heat treatment in a flow of oxygen gas at low temperature such as 533 K or lower. High-resolution transmission electron microscopy was used to directly observe vacancy structures, which were compared with image simulations. These proposed structures contain C═O, pyran-like ether, and lactone-like groups.

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“…The most commonly used metal ions for coordination with functionalized graphene ligands include copper and nickel. 151,152 Graphene can be combined with EMs or functionalized with energetic groups. The first reported case showed that graphene can be a good carrier for laying molecular monolayers of an insensitive explosive, 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), which was attributed to the strong π-π attraction between the TATB and graphene sheets ( Fig.…”

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confidence: 99%