Near‐Quantitative Solid‐State Synthesis of Carbon Nanotubes from Homogeneous Diphenylethynecobalt and –Nickel Complexes

Abstract

Carbon nanotubes (CNTs) have generated a tremendous amount of research interest because of their unique structural, electronic, magnetic, and mechanical properties. [1] Among the various synthetic methods employed for their preparation, chemical vapor deposition (CVD) has emerged to be most effective, and efforts are increasing in applying this technique to pre-growth device fabrication by utilizing (in particular lithographically) [2] patterned catalyst arrays and in situ tube assembly. [2,3] Crucial in this endeavor is the sitespecific batch production of ordered carbon with control of stoichiometry and ultimately morphology. One possible approach to achieving this would be the efficient thermal conversion of a defined, soluble, molecular organometallic precursor composed of both the carbon source and the metal catalyst, placed locospecifically by wetting and drying. Such a strategy would combine the advantages of the floating organometallic catalyst (for example, ferrocene, [Fe(CO) 5 ], etc.) CVD methodology [1d, 4] with a solid-state conversion of carbon precursors. Reports of the latter reveal some serious shortcomings with respect to yield and/or degree of graphitization, extremity of conditions, need for specialized equipment, the requirement of co-reagents, and simplicity of starting materials. [1d, 5] We have described the solid-state thermolysis of a [Co 2 (CO) 6 ]-complexed tetrabenzodehydro [20]annulene and some of its substructures to form ordered carbon material, but this method shared some of these drawbacks, in as much as the highest yields were only about 60 %. The desired product consisted of an (at best) approximately equal mixture of multiwalled tubes (MWNTs)

The Chemistry of Organic Nanomaterials

“…The solid-state pyrolysis of organometallic compounds such as metallo-dehydro[n]annulenes has emerged as a new method for making CNTs (primarily MWNTs). [376][377][378][379] The pyrolysis of an HBC-cobalt complex 141 in the solidstate produces carbon nanotubes ( Figure 13). [380] Nearly quantitative yields of either "bamboo-shaped" or straight nanotubes are obtained.…”

Low temperature synthesis of multiwall carbon nanotubes from carbonaceous solid prepared by sol–gel autocombustion

“…Various methods have been developed for the synthesis of CNTs, such as arc discharge [3], laser vaporization of a graphite electrode in the presence of metal catalysts [4], catalytic decomposition of hydrocarbon vapor over a transition metal incorporated silica or zeolite support [5,6], pyrolysis of metallocene [7], detonation-assisted synthesis [8], etc. Recently, it was reported that CNTs can also be synthesized by solid-phase transformation of carbonaceous materials containing metal particles [9][10][11]. Various kinds of materials, such as carbon black, amorphous carbon, fullerene soot and kinds of polymers can be used as raw materials in the solid-phase transformation synthesis.…”

Nanostrukturierte Kohlenstoffmaterialien aus molekularen Vorstufen

“…Die Autoren vermuteten daher, dass der Prozess mit einer Cyclotrimerisierung des Übergangsmetallkomplexes beginnt. [189] Die Komplexierung von PAKs mit Cobalt-Katalysatoren wurde mit Hexakis(1-dodecylethinyl)-HBC und [Co 2 (CO) 8 ] realisiert, wobei die eigentliche Komplexierung über die Acetylenreste des HBC-Derivats erfolgte. Nach erstem Erhitzen auf 250 8C fand die Pyrolyse bei 600 8C, 800 8C oder 1000 8C statt.…”

“…Mitunter enthielten die Spitzen kleine Cobaltkristalle. [189] ¾hnlich zu der Herstellung von Kohlefasern aus Polyacrylnitril lassen sich Polymere als Vorstufen unter Erhaltung ihrer mesoskopischen Struktur zur Herstellung nanostrukturierter Kohlenstoffmaterialien in der Übergangsmetall-katalysierten Pyrolyse einsetzen. Zum Beispiel synthetisierten Jang und Yoon Nanopartikel bestehend aus Polypyrrol (PPy) mit einem Durchmesser von 62 nm durch Emulsionspolymerisation von Pyrrol mit FeCl 3 .…”