New Pathway for Heterogenization of Molecular Catalysts by Non-covalent Interactions with Carbon Nanoreactors

Lebedeva, Maria A.; Chamberlain, Thomas W.; Schröder, Martin; Khlobystov, Andrei N.

doi:10.1021/cm502986d

Cited by 25 publications

(15 citation statements)

References 51 publications

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“…The perfect geometrical match of truncated icosahedral fullerene cages and the tubular interior of nanotubes provide extremely effective van der Waals interactions that can be as high as 3 eV per molecule . In contrast, although metal complexes have been encapsulated in nanotubes for a wide variety of applications, including catalysis, spintronics, and sensors, very little has been reported about the nature of their interactions with the nanotube cavity. The electric charge, asymmetrical distribution of the electron density, and the irregular shape of metal complexes make this a difficult challenge.…”

Section: Resultsmentioning

confidence: 99%

Direct Measurement of Electron Transfer in Nanoscale Host–Guest Systems: Metallocenes in Carbon Nanotubes

McSweeney

Chamberlain

Baldoni

et al. 2016

Chemistry A European J

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Electron transfer processes play a significant role in host-guest interactions and determine physicochemical phenomena emerging at the nanoscale that can be harnessed in electronic or optical devices as well as biochemical and catalytic systems. We have developed a novel method for qualifying and quantifying the electronic doping of single walled carbon nanotubes (SWNT) using electrochemistry and have established a direct link between these experimental measurements and ab initio DFT calculations. Metallocenes such as cobaltocene and methylated ferrocene derivatives were encapsulated inside SWNT (1.4 nm diameter) and the cyclic voltammetry (CV) performed. The electron transfer between guest-molecules and host-SWNT is measured as a function of shift in the redox potential (E1/2) . Furthermore, the shift in E1/2 is shown to be inversely proportional to the nanotube diameter. For the quantification of the amount of electron transfer from the guestmolecules on the SWNT, a novel method using coulometry was developed allowing the mapping of the density of states (DOS) and the Fermi level of the SWNT. Correlated with theoretical calculations, coulometry provides an accurate indication of n/p-doping of the SWNT.

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Section: Resultsmentioning

confidence: 99%

Direct Measurement of Electron Transfer in Nanoscale Host–Guest Systems: Metallocenes in Carbon Nanotubes

McSweeney

Chamberlain

Baldoni

et al. 2016

Chemistry A European J

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“…This creates localised nanoscale reaction environments, different to the bulk phase, which impart spatial restrictions and thus can significantly impact the yields and distributions of products afforded across a range of preparative chemical transformations, as demonstrated by us and others. [37][38][39][40][41][42][43][44][45][46][47][48]…”

Section: Introductionmentioning

confidence: 99%

Cerium Oxide Nanoparticles Inside Carbon Nanoreactors for Selective Allylic Oxidation of Cyclohexene

et al. 2020

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The confinement of cerium oxide nanoparticles within hollow carbon nanostructures has been achieved and harnessed to control the oxidation of cyclohexene. Graphitised carbon nanofibres (GNF) have been used as the nanoscale tubular host and filled by sublimation of the Ce(tmhd)4 complex (where tmhd = tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)) into the internal cavity, followed by a subsequent thermal decomposition to yield the hybrid nanostructure CeO2@GNF, where nanoparticles are preferentially immobilised at the internal graphitic step-edges of the GNF.Control over the size of the CeO2 nanoparticles has been demonstrated within the range c.a. 4 to 9 nm by varying the mass ratio of the Ce(tmhd)4 precursor to GNF during the synthesis. CeO2@GNF were effective in promoting the allylic oxidation of cyclohexene, in high yield, with timedependent control of product selectivity, at a comparatively low loading of CeO2 of 0.13 mol%.Unlike many of the reports to date where ceria catalyses such organic transformations, we found the encapsulated CeO2 to play the key role of radical initiator due to the presence of Ce 3+ included in the structure, with the nanotube acting as both a host, preserving the high performance of the CeO2 nanoparticles, anchored at the GNF step-edges, over multiple uses, and an electron reservoir, maintaining the balance of Ce 3+ and Ce 4+ centers. Spatial confinement effects ensure excellent stability and recyclability of CeO2@GNF nanoreactors.

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“…The synthetic strategy for hollow graphitic carbon nanofibers (HGCNFs) with nanometer-sized pores or channels is believed to be important for many applicationsfor example, as catalyst or sensor supports, [1][2][3][4][5][6][7] as hydrogen-storage materials, 8 for gas storage, 9 and in electronic and electrochemical devices 10,11 -because of their distinctive one-dimensional (1D) structure, high structural and thermal stability, high surface area, and high electric and thermal conductivity. Several methods, such as the chemical vapor deposition (CVD) approach, [12][13][14] hydrothermal method, [15][16][17][18] and electrospinning technique, have been developed for the synthesis of HGCNFs.…”

Section: Introductionmentioning

confidence: 99%

A Catalytic Etching-Wetting-Dewetting Mechanism in the Formation of Hollow Graphitic Carbon Fiber

Chen

Dong

Qiu

et al. 2017

Chem

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Hollow graphitic carbon nanofibers (HGCNFs) have great promise for many important applications, such as catalysis, sensors, energy conversion, gas storage, and electronic devices. Here, we report a catalytic etching-wettingdewetting mechanism in synthesizing HGCNFs with both hollow sphericallike and tunnel-like pores. With in situ transmission electron microscope imaging, we show that the spherical pores are formed by the evaporation of encapsulated Ni on the surface of amorphous carbon nanofiber and that hollow tunnels are developed through continuous etching of the amorphous carbon under catalysis of Ni nanoparticles. Theoretical calculations and simulations reveal that continuous tunnel etching is driven by the wetting-to-dewetting transition of the Ni-tunnel wall interaction during the catalytic graphitization of the amorphous carbon wall. In a typical application, we demonstrate that the synthesized HGCNFs, with a capacity about three times higher than that of their non-hollow counterparts, are excellent potential candidates for CO 2 capture.

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New Pathway for Heterogenization of Molecular Catalysts by Non-covalent Interactions with Carbon Nanoreactors

Cited by 25 publications

References 51 publications

Direct Measurement of Electron Transfer in Nanoscale Host–Guest Systems: Metallocenes in Carbon Nanotubes

Direct Measurement of Electron Transfer in Nanoscale Host–Guest Systems: Metallocenes in Carbon Nanotubes

Cerium Oxide Nanoparticles Inside Carbon Nanoreactors for Selective Allylic Oxidation of Cyclohexene

A Catalytic Etching-Wetting-Dewetting Mechanism in the Formation of Hollow Graphitic Carbon Fiber

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