Tailoring of the chlorine sensing properties of substituted metal phthalocyanines non-covalently anchored on single-walled carbon nanotubes.

To investigate how central metal tunes the synergetic interactions between substituted metallo-phthalocyanine and single-walled carbon nanotubes in enhancing the gas sensing properties, a comparative study has been performed by varying the central metal ion in fluorinated metal phthalocyanines and single-walled carbon nanotube hybrid. Hybrids of metal(ii)-1,2,3,4,8,9,10,11,15,16,17,18-24,25-hexa-decafluoro-29,31-phthalocyanine/single-walled carbon nanotube (FMPc/SWCNTs-COOH, where M = Co, Zn) have been synthesized through π-π stacking interactions using the solution route. Spectroscopic (FT-IR, UV-vis, XPS and Raman), electron microscopic (TEM and FE-SEM) and TGA investigations have confirmed the successful functionalization and interaction of SWCNTs-COOH with FMPc. Parts per billion (ppb) level Cl-selective chemiresistive gas sensors have been fabricated on glass substrates with precoated gold electrodes by using these hybrids. The responses of various FMPc/SWCNTs-COOH sensors have demonstrated the central metal ion-dependence in the sensitivity of Cl.