EFFECT OF THE METAL SPECIES COMPOSING PHTALOCYANINE BASED PRECURSORS ON PROPERTIES OF SELF-ALIGNED MULTI-WALLED CARBON NANOTUBES ARRAYS

A. L. CUKIERMAN; D. ZILLI; P. BONELLI

Tel Aviv

Congreso; NanoIsrael 2012 The 3rd International Conference & Exhibition; 2012

Kenes Exhibitions

The effect of the metal species composing phtalocyanine-based precursors on properties of macroscopic self-aligned arrays of carbon nanotubes (CNTs), lab-synthesized by floating catalyst chemical vapor deposition, is investigated. Iron (II) and cobalt (II) phtalocyanines, and identical synthesis conditions (895 ºC, total gas flow rate of 30 cm3/min, H2 molar fraction of 0.5, and reaction time of 90 min) are used. The arrays are subjected to purification sequentiallyinvolving partial oxidation in gas-phase, removal of oxide nano-particles, and ultrasound dispersion. Textural properties of the pristine and purified arrays are evaluated  rom N2 (-196 ºC) adsorption isotherms, and related to morphological features determined by scanning and transmission electron microscopy (SEM, TEM). Thermal stability is ascertained by dynamic thermogravimetric analysis in oxidation conditions, from room temperature up to 1000 ºC. The iron precursor leads to CNTs arrays with BET surface area (55 m2g-1) and total pore volume (0.11 cm3g-1) that almost duplicate the values obtained for those synthesized from the Cocompound. The behavior is related to better alignment and denser structures for the iron precursor-derived arrays (Figure 1), which show narrower interspaces between neighboring CNTs, predominantly contributing to N2 adsorption. After purification, the arrays arising from both precursors show similar textural parameters, owing to pronouncedly disarranged bidimensional structures occasioned by ultrasound dispersion. Furthermore, the pristine and purified CNTs synthesized from the Fe-precursor show higher thermal stability than those involving cobalt. Nevertheless, purification leads to enhance the thermal stability of the arrays regardless of the metallic species involved.3/min, H2 molar fraction of 0.5, and reaction time of 90 min) are used. The arrays are subjected to purification sequentiallyinvolving partial oxidation in gas-phase, removal of oxide nano-particles, and ultrasound dispersion. Textural properties of the pristine and purified arrays are evaluated  rom N2 (-196 ºC) adsorption isotherms, and related to morphological features determined by scanning and transmission electron microscopy (SEM, TEM). Thermal stability is ascertained by dynamic thermogravimetric analysis in oxidation conditions, from room temperature up to 1000 ºC. The iron precursor leads to CNTs arrays with BET surface area (55 m2g-1) and total pore volume (0.11 cm3g-1) that almost duplicate the values obtained for those synthesized from the Cocompound. The behavior is related to better alignment and denser structures for the iron precursor-derived arrays (Figure 1), which show narrower interspaces between neighboring CNTs, predominantly contributing to N2 adsorption. After purification, the arrays arising from both precursors show similar textural parameters, owing to pronouncedly disarranged bidimensional structures occasioned by ultrasound dispersion. Furthermore, the pristine and purified CNTs synthesized from the Fe-precursor show higher thermal stability than those involving cobalt. Nevertheless, purification leads to enhance the thermal stability of the arrays regardless of the metallic species involved.