Study of the effect of orbital on interaction behaviour of SWCNT- metal phthalocyanines composites with ammonia gas

摘要

The present study deals with analysing the effect of central metal atom on interaction behaviour of a composite constituted of two materials, Single walled carbon nanotubes (SWCNT) and metal phthalocyanines (MPcs) (SWCNT-MPc) with ammonia gas. For this purpose, three metal phthalocyanines namely; Magnesium phthalo-cyanine (MgPc), Aluminum phthalocyanine hydroxide (AlPcOH) and Titanyl phthalocyanine (TiOPc) were taken and their variation in resistances with exposure of ammonia gas is taken as detection parameter. The central metal ions of MPcs were chosen so that valence electrons are in s, p and d orbitals respectively. The surface-interface interaction of pristine SWCNT towards ammonia gas was found to increase with better repeatability and stability after addition of MPcs. SWCNT-TiOPc composite exhibited maximum interaction with ammonia vapors (≈ 3 times pristine SWCNT) followed by SWCNT- MgPc (≈ 2 times pristine SWCNT), while AlPcOH had shown faster desorption (≈ 0.5 times faster) as compared to pristine SWCNT during recovery stage. The concept of charge transfer mechanism between SWCNT-MPcs and ammonia gas and varied orbital state accommodating ammonia lone pairs were used to explain interaction studies. Consistencies observed in physics and chemistry analysis highlighted the significance of both these fields to have complete understanding of the interaction phenomena between SWCNT-MPcs and ammonia gas.