Temperature-Dependent Growth of 36 Inner Nanotubes inside Nickelocene, Cobaltocene and Ferrocene-Filled Single-Walled Carbon Nanotubes

Abstract

We have investigated the effects of temperature, diameter and metal catalyst type on the growth of inner nanotubes inside metallocene-filled single-walled carbon nanotubes (SWCNTs). The effects on the yield of different chiralities of inner nanotubes were scrutinized by multifrequency Raman spectroscopy. The investigated diameters range from ~0.7 to 1.3 nm and comprise 36 distinct chiralities. For all three investigated metals (Ni, Co, Fe), there is a linear correlation of growth temperature with nanotube diameter. The common slope for these metals is found to be 40.5 °C/Å. The temperature difference between the largest and the smallest diameter tubes amounts to ~230 °C for all three precursors. The growth temperatures are offset by 34 °C from Ni to Co and another 28 °C from Co to Fe. The quantified correlations of temperature, diameter and metal catalyst type provide the basis for engineering the diameter-specific growth of nanotubes.

Kinetics, Electronic Properties of Filled Carbon Nanotubes Investigated with Spectroscopy for Applications

“…Raman spectroscopy is nondestructive method of investigation of the electronic properties of SWCNTs. The shifts of bands and their modifications are analyzed, and modification of the electronic properties is studied [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 41 , 42 , 43 , 44 , 46 , 47 , 49 , 50 , 51 , 55 , 56 , 57 , 61 , 62 , 63 , 64 , 65 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 ].…”

“…It is found that different fillers lead to changes in electronic structure of nanotubes with n- or p-doping. The insertion of metal halogenides, metal chalcogenides, metallocenes, and metals leads to the Fermi level shift of −0.3–0.4 eV, −0.3 eV, +0.05–0.1 eV, and +0.3 eV [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 41 , 42 , 43 , 44 , 46 , 47 , 49 , 50 , 51 , 55 , 56 , 57 , 61 , 62 , 63 , 64 , 65 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 ]. The encapsulation of rubidium iodide leads to the Fermi level shift of +0.2 eV, i.e., donor doping [ 47 ].…”

Electrochemistry of Carbon Materials: Progress in Raman Spectroscopy, Optical Absorption Spectroscopy, and Applications

“…There is a large field of work on chemically functionalized carbon nanotubes. It was shown that metal halogenide-filled SWCNTs with a decreased [ 145 , 146 , 147 , 148 , 149 , 150 , 151 , 152 , 153 , 154 , 155 , 156 , 157 , 158 , 159 , 160 ] Fermi level, metal chalcogenide-filled SWCNTs [ 161 , 162 , 163 ], metal-filled SWCNTs [ 164 , 165 , 166 ], metal halogenide-filled SWCNTs [ 167 ], and metallocene-filled SWCNTs [ 168 , 169 , 170 , 171 , 172 , 173 , 174 , 175 , 176 , 177 , 178 , 179 , 180 , 181 ] with an increased Fermi level can be used for the electrochemical measurements.…”

“…Raman spectroscopy is used to identify the charge transfer and electronic and vibronic properties of filled SWCNTs [ 181 , 182 , 183 , 184 , 185 ]. Figure 18 shows the Raman spectra of pristine and cobalt iodide-filled SWCNTs obtained at different laser wavelengths [ 238 ].…”

“…XPS is used to identify the direction and value of the Fermi level shift of the filled SWCNTs [ 145 , 146 , 147 , 148 , 149 , 150 , 151 , 152 , 153 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 162 , 163 , 164 , 165 , 166 , 167 , 168 , 169 , 170 , 171 , 172 , 173 , 174 , 175 , 176 , 177 , 178 , 179 , 180 , 181 ]. Figure 19 shows the XPS spectra of pristine and gallium selenide-filled SWCNTs [ 162 ].…”