Synthesis and Characterization of Polyaniline and its Composites for Opto Electrical Sensing Applications

Abstract

Ammonia (NH3) is a widely used chemical in various chemical production, industrial, agriculture (fertilizers), and refrigeration. The need for ammonia sensors arises from the toxic, corrosive, and environmentally damaging properties of NH3. Reliable and efficient ammonia sensors are vital for maintaining safe workplaces, protecting the environment, and complying with safety and environmental regulations. Traditionally, pure organic ammonia sensors (e.g., Polyaniline, Polypyrrole) are advantageous for applications requiring room temperature operation, flexibility and low-cost fabrication, but they are limited by lower stability, slower response, and poor selectivity. Pure inorganic ammonia sensors (e.g., Metal Oxides: ZnO, SnO2) offer high sensitivity, fast response times, and stability in harsh conditions but require high temperatures, making them less suitable for portable, low-power applications and limiting their mechanical flexibility. These drawbacks drive the need for organic-inorganic hybrid sensors, which can combine the best properties of both material types-addressing limitations like poor selectivity, slow response, and environmental instability while providing the higher sensitivity and more stable performance. This thesis investigates the synthesis of pure polyaniline and its composites with ZnO, SnO2, and rGO for improvements in structural, optical, electrical, and gas sensing properties. Polyaniline and its composites with ZnO, SnO2, and rGO offer significant improvements in the sensitivity, response time, and stability of ammonia sensors. These materials are highly desirable for developing reliable and efficient ammonia sensors for industrial, environmental, and safety applications. Polyaniline- based composites show great potential for addressing the limitations of traditional sensors, providing a promising solution for real-time ammonia monitoring. Our study demonstrates notable improvements in the sensing capabilities, as well as enhanced selectivity and stability, of polyaniline composite materials, establishing them as effective solutions for ammonia detection and for ensuring environmental safety and protection.