Highly sensitive and selective chemiresistor gas/vapor sensors based on polyaniline nanocomposite: A comprehensive review

This review article directs particular attention to some current breakthrough developments in the area of gas sensors based on polyaniline (PANI) nanocomposite. Conducting polymers symbolize a paramount class of organic materials that boost the resistivity towards external stimuli. Nevertheless, PANI-based sensor experiences some disadvantages of relatively low reproducibility, selectivity, and stability. In order to overcome these restrictions, PANI was functionalised or incorporated with nanoparticles (NPs) (metallic or bimetallic NPs, metal oxide NPs), carbon compounds (like CNT or graphene, chalcogenides, polymers), showing improved gas sensing characteristics. It has been suggested that host-guest chemistry combined with the utilization of organic and inorganic analog in nanocomposite may allow for improvement of the sensor performance due to synergetic/complementary effects. Herein, we summarize recent advantages in PANI nanocomposite preparation, sensor construction, and sensing properties of various PANI nanocomposite-based gas/vapor sensors, such as NH3, H2, HCl, NO2, H2S, CO, CO2, SO2, LPG, vapor of volatile organic compounds (VOCs) as well as chemical warfare agents (CWAs). The sensing mechanisms are discussed. Existing problems that may hinder practical applications of the sensors are also discussed.