Gas-sensitive sensors based on polyaniline for monitoring CO, CH4 and NO2 at room temperature

Abstract

This study is dedicated to the 60th anniversary of Professor Bakhytzhan Tastanovich Lesbaev – a leading expert in the fields of combustion, nanomaterials, and functional carbon systems, who has made a significant contribution to the advancement of interdisciplinary research at the intersection of nanotechnology, energy, and environmental science. As industrial growth accelerates and hydrocarbon fuel usage expands, developing advanced sensor materials for tracking toxic emissions from incomplete combustion has become increasingly critical. Among the most hazardous byproducts of hydrocarbon fuel combustion are carbon monoxide (CO), methane (CH₄), and nitrogen dioxide (NO₂). These compounds exhibit high toxicity: carbon monoxide causes hypoxia, methane contributes to the greenhouse effect, and nitrogen dioxide irritates the respiratory tract and participates in the formation of photochemical smog. Moreover, they promote the generation of secondary pollutants, including ozone and fine particulate matter. This work investigates the potential of polymerized polyaniline (PANI) as a gas-sensitive material capable of selectively detecting these gases at room temperature. Experimental data are presented on the response of a PANI-based sensing layer – synthesized via chemical oxidative polymerization – when exposed to both reducing and oxidizing gases. The mechanisms of interaction are analyzed, including doping, charge transfer, and the influence of morphological parameters on sensor response. Key factors affecting sensitivity, selectivity, reproducibility, and operational stability are identified. The obtained results confirm the high efficiency of polyaniline as an active sensing material and substantiate its use in flexible, energy-efficient sensing platforms aimed at environmental monitoring and combustion process optimization with minimized harmful emissions.