CNTs based improved chlorine sensor from non-covalently anchored multi-walled carbon nanotubes with hexa-decafluorinated cobalt phthalocyanines

Abstract

To study the effect of synergetic interactions between metal-phthalocyanine and carbon nanotubes for gas sensing characteristics of carbon nanotubes, we synthesized a hybrid of cobalt(ii)-1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexa-decafluoro-29H,31H-phthalocyanine/multi-walled carbon nanotubes (F16CoPc/MWCNTs-COOH). The as-prepared hybrid was characterized through spectroscopic (FT-IR, UV-vis and Raman), electron microscopic (TEM and FE-SEM) and TGA investigations that confirmed the successful non-covalent anchoring of F16CoPc onto MWCNTs-COOH through π-π stacking interactions. Further, a highly reversible, reproducible, sensitive and Cl2 selective chemiresistive sensor was fabricated using F16CoPc/MWCNTs-COOH hybrid, which exhibited a sensitivity of ∼63% for 2 ppm of Cl2 and a limit of detection as low as 0.05 ppb. A plausible gas sensing mechanism for improved gas sensing characteristics of F16CoPc/MWCNTs-COOH sensor towards Cl2 was explained using Raman, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) studies. Herein, cobalt metal ion is found to play an important role in enhancing gas sensing characteristics of the fabricated sensor.