NH 3 -detecting room temperature PANI-TiO 2 -based flexible gas sensor with EIS-validated sensing mechanism

PANI-metal oxide nanocomposites have been studied extensively to improve sensor performance at room temperature. To date, researchers have utilized PANI-TiO 2 for sensing NH 3, but no elucidation of the sensing mechanism has been reported. In this research work, PANI-TiO 2 nanocomposite-based flexible gas sensor for detecting NH 3 , operating at room temperature, has been investigated. The novelty lies in elucidating the sensing mechanism using electrochemical impedance spectroscopy (EIS) study. Effects of the operating temperature and different humidity levels of the CDA environment on the sensing parameters of the devices are also studied. PANI-TiO 2 (10 wt% TiO 2 with respect to aniline) device showed the best response of 9.88% against 2 ppm of NH 3 at 21 °C. The sensor can detect NH 3 as low as 2 ppm within 10 seconds. A low deviation of 3.5% in sensor response after 100 bending cycles was observed. Further, the sensor maintained a near-consistent response even after seven months of fabrication. Moreover, linearity was observed in the I-V analysis, providing further evidence that devices are ohmic. Furthermore, the contributions of the bulk, grain boundary, depletion region, and resistance between the electrode and the sensing film in the sensor response were identified by the EIS studies.