High-Density Monodispersed Cobalt Nanoparticles Filled into Multiwalled Carbon Nanotubes

Abstract

Magnetic cobalt-based nanoparticles (NPs) with homogeneous size were selectively cast inside the channel of multiwalled carbon nanotubes (CNTs). The proposed synthesis method allows for filling only the CNTs channel with an unprecedented high density. The CNTs act as “nanoreactors” and provide protection against oxidation.

Magnetically Active Carbon Nanotubes at Work

“…In the same vein, Liu et al. very recently demonstrated the possibility to use amino‐functionalized Co and Fe oxides MNPs@CNTs, produced from the stearate precursors method developed earlier by the same team66 (Figure 5), for magnetic manipulation of cells in‐vitro 102. They were able to show that, depending on the direction and the frequency of the field applied, their hybrids can be either taken up by cells, drive cell motion, or act as a remote “nano‐stirring bar” in the biological media.…”

“…for encapsulating monodisperse 50 nm‐diameter MNPs of Co (Figure 5). 66 For this purpose, cobalt stearate impregnated in open‐tips CNTs was used as a precursor for the thermal transformation reaction 32a. 69 Reference thermal reduction experiments in the absence of the carbon frameworks showed the limited formation of NPs thus confirming the templating role exerted by the nanotube cavity on the nanoparticle synthesis.…”

“… TEM pictures of Co‐based MNPs@CNTs prepared by thermal decomposition of cobalt stearate. Reproduced with permission from reference 66. …”

“…The synergy between MNPs and CNTs can also take place during the synthesis. As discussed above, the inner cavity of CNTs can act as a “nano‐reactor” and template the synthesis of monodisperse Co NPs 66. On the other hand, MNPs can also be used to govern the growth of different types of CNTs.…”

Mesoporous binder-free monoliths of few-walled carbon nanotubes by spark plasma sintering

“…The Raman I D /I G ratio for the monoliths (Table 2) lower than that found prior to consolidation (Table 1), which could reflect the elimination of surface defects and formational defects in the CNT outer walls by a thermal annealing effect during SPS. Indeed, other authors [41,42,46] have reported that oxygen functional groups can be selectively removed from a CNT surface and formational defects can anneal out at relatively low temperatures, below 1600°C, whereas microstructural defects within the MWCNT structure require subsequent annealing at much higher temperatures (typically above 3000°C). The trend, however, is that the I D /I G ratio increases upon the increase in temperature and this density (Fig.…”