Carbon and graphene based nanocomposites for gas sensors—Current state and advances

Abstract

After the discovery of carbon nanoforms, carbon nanotube (one dimensional) and tube like nanostructure and graphene (two dimensional) nanosheets have gained immense research curiosity. Further nanotechnological developments have moved towards the formation of carbon nanotube nanocomposites and graphene nanocomposites. For the purpose, various matrices including thermoplastic polymers and conjugated polymers have been used. Methodology is the systematic gathering of the literature and development of a novel review outline, theme, and discussions regarding the discussed topics. Hence, varying conjugated polymers such as polyaniline, polythiophene, poly(3,4-ethylenedioxythiophene), and nonconjugated nylon, poly(ethylene glycol), etc. have been processed using techniques like in situ, solution, electropolymerization, spin coating, etc. In sensors, the nanocomposites need to develop fine nanoparticle dispersion, network formation, and interfacial interactions ultimately supporting the electron or charge transfer in these nanomaterials desirable for the recognition of the gaseous species. Moreover, interactions of the nanocomposite with the analyte molecules define the sensing capabilities of the nanomaterials. Consequently, nanocarbon nanocomposite based gas sensors have been analyzed for conductivity, change in resistance, sensitivity, selectivity, response time, detection limit, and other desirable properties. For future designs, it is recommended to develop high-tech combinations of conjugated polymers like polythiophene derivatives using functional forms of graphene and carbon nanotube. In addition, use of advanced manufacturing techniques like 3D/4D printing and spin coating must be applied to form efficient sensors. In conclusions, this manuscript presents not only comprehensive but also comparative analysis on different gas analysis parameters such as detection limit, concentration, response time, etc. for various nanocomposite sensors. Lastly, the encounters in preparing and applying graphene/carbon nanotube sensors, associated utilizations, and possible future prospects have been discussed.