Potassium Iodide-Functionalized Polyaniline Nanothin Film Chemiresistor for Ultrasensitive Ozone Gas Sensing

Polyaniline (PANI) nanostructures have been widely studied for their sensitivity to atmospheric pollutants at ambient conditions. We recently showed an effective way to electropolymerize a PANI nanothin film on prefabricated microelectrodes, and demonstrated its remarkable sensing performance to be comparable to that of a one-dimensional nanostructure, such as PANI nanowires. In this work, we report further progress in the application of the PANI nanothin film chemiresistive sensor for the detection of ozone (O3) by modifying the film with potassium iodide (KI). The KI-PANI sensor exhibited an excellent sensitivity to O3 (8–180 ppb O3 concentration rage) with a limit of detection of 230 ppt O3, and exquisite selectivity against active chemicals such as nitrogen dioxide (NO2) and sulfur dioxide (SO2). The sensing mechanism of the sensor relied on iodometric chemistry of KI and O3, producing triiodide (I− 3 ) that partially doped and increased electrical conductivity of the PANI film. The sensitivity and selectivity of the KI-functionalized PANI film demonstrates the potential use for KI-PANI-based O3 sensing devices in environmental monitoring and occupational safety.