Conformally coating vertically aligned carbon nanotube arrays using thermal decomposition of iron pentacarbonyl
Schematic of test equipment. A pump and N2 are connected to a Schlenk line to provide vacuum and N2 for purging. Chamber C1 holds the Fe(CO)5 and is connected to the low-pressure chamber, C2, via valve V1. Chamber C3 holds the CNT array and is connected to low-pressure chamber C2 via valve V2. A hot plate set at 220 °C is mounted on a raiser to heat the bottom of C3 after Fe(CO)5 vapor is introduced into C3. The pressure is monitored at the Schlenk line while a noncontact IR sensor monitors the temperature of the CNT array.
SEM micrographs of CNTs after (A) 0 cycles, Ø 15 nm; (B) 5 cycles, Ø 40 nm; (C) 20 cycles, Ø 125 nm. The coated CNTs micrographs were taken from the center of the sample near the bottom of the CNT array. The large amount of curvature is typical of CNTs located near the substrate and is not an artifact from the coating process. All scale bars are set to 200 nm as indicated in (A).
XPS data showing (A) survey scan and (B) 700–740 eV scan across the Fe 2p energies show the presence of primarily iron oxides on the surface of the iron carbonyl treated CNTs.
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