In this paper, we have performed the filling of single‐walled carbon nanotubes (SWCNTs) with mean diameters of 1.4 and 1.9 nm synthesized by the arc‐discharge and chemical vapor deposition (CVD) methods, respectively, with silver chloride. The doping effect of the encapsulated compound on SWCNTs is studied by Raman spectroscopy and X‐ray photoelectron spectroscopy. It is shown that the filling of nanotubes with silver chloride leads to p‐doping of SWCNTs accompanied by charge transfer from the SWCNTs to the salt and downshift of their Fermi level. It is found that the filling of SWCNTs synthesized by different methods results in different doping levels of nanotubes. The arc‐discharge 1.4 nm‐diameter SWCNTs have larger doping level than CVD 1.9 nm‐diameter nanotubes. The obtained information about the influence of the filler on the electronic properties of SWCNTs synthesized by different methods is elemental for applications of nanotubes in nanoelectronic devices.
Ensembles of fcc nickel nanowires have been synthesized with defined mean sizes in the interior of single-wall carbon nanotubes. The method allows the intrinsic nature of single-domain magnets to emerge with large coercivity as their size becomes as small as the exchange length of nickel. By means of X-ray magnetic circular dichroism we probe electronic interactions at nickel-carbon interfaces where nickel exhibit no hysteresis and size-dependent spin magnetic moment. A manifestation of the interacting two subsystems on a bulk scale is traced in the nanotube’s magnetoresistance as explained within the framework of weak localization.
The properties of single-walled carbon nanotubes provide them with enormous potential as gas sensors but true effectiveness can really be expected if their interaction with sensing targets can be controlled and their recovery is granted. It is shown here how metallicity-sorted tubes filled with nickel(II) acetylacetonate in the molecular form, and also subsequently transformed into metal clusters encapsulated in the hollow core, are able to unfold two major challenges: tuning the gas-tube interaction and achieving the desorption of NO 2 at ambient temperature. Aiming at the control of the sensitivity of the nanotubes to NO 2 at room temperature, by making use of time resolved photoemission we observed that in semiconducting nanotubes the chemical potential is pinned inside their energy gap shifted to the onset of the conduction band when filled with nanoclusters. This shows that cluster filling is a key to high sensitivity, opening the possibility for a very high desorption at ambient temperature. Fig. 3 (a) Shift of the main peak of the C 1s core level signal in XPS of the semiconducting (blue) vs. metallic (red) hosts with different fillings at the stages listed in Table 1. (b) C 1s shift resulting from a time resolved experiment by exposing the Ni-nc@SC-SWCNTs to NO 2 .This journal is Fig. 4 C 1s core level spectra of Ni-acc@SC-SWCNTs (a) and Ni-acac@M-SWCNTs (b). The spectra correspondingly below (c and d) were recorded after exposure to 80 L of NO 2 . The bottom spectra correspond to Ni-nc@SC-SWCNTs (e) and Ni-nc@M-SWCNTs (f) exposed to 80 L of NO 2 . Molecular models are shown as the inset of each plot. 9756 | J. Mater. Chem. A, 2020, 8, 9753-9759 This journal is
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