Metal Porphyrins Functionalized Carbon Nanotubes as Sensor for Some Chemical Vapors

Abstract

The Thesis entitled Metal-Porphyrin Functionalized Carbon Nanotubes as Sensor for Some Chemical Vapors by Swasti Saxena deals with the development of chemical vapor sensors with fast response and recovery times utilizing nanocomposites prepared by non-covalent functionalization of multi-walled carbon nanotubes (MWNTs) with metal-tetraphenylporphyrins (M-TPP) and metal-phthalocyanines (s). Nanosized clusters of M-TPP anchor MWNTs on functionalization with M-TPP and M-Pc as revealed by TEM and SEM images and supported by FTIR and XRD experiments. These nanosized clusters act as receptor for adsorption of chemical vapors which affect the conductivity of MWNTS / M-TPP complex. The details of studies carried out in this thesis are divided in to six chapters. Chapter 1 deals with the introduction to the subject and review of literature. Chapter 2 deals with the different characterization techniques utilized in this work which are: FTIR, TEM, SEM microscopy, X-ray diffraction and conductivity measurements. Information obtainable from each technique is also discussed. The main research work is described in chapters 3 to 5. Chapter 3 deals with the sensors for detection of H2O2 and NO2 vapors. Due to highly toxic nature of H2O2 vapors and use in explosive devices, its level needs to be monitored with reliability. Similarly, nitrogen dioxide (NO2) is a highly reactive and toxic gas from exhaust of vehicles, chimneys etc. The prepared nano-composites have been used to develop sensitive and selective sensors for detection of H2O2 and NO2 vapors. A pair of sensors made from Co-Pc and Cu-Pc functionalized MWNTs composites show opposite electrical responses to H2O2 vapors while their responses are similar to other chemical vapors. The nano-composites have been used to prepare very sensitive sensors for detection of hazardous BTX vapors (Chapter 4). The prepared sensors show differential changes in resistance, response and recovery times on exposure to benzene, toluene or xylene vapors