UV enhanced ammonia gas sensing properties of PANI/TiO2 core-shell nanofibers

TiO2/PANI core-shell nanofiber thin film sensors are fabricated by in-situ chemical polymerization on electrospun TiO2 nanofibers, and evaluated for NH3 gas sensing application with UV irradiation at room temperature (25 degrees C). Fully rutile and 30% anatase-70% rutile mixed phase TiO2 nanofibers are used as n-type core material. PANI as a p-type shell has porous morphology and FE-SEM results reveal that the average thickness of PANI shell is about 20 nm, which is in the order of Debye length resulting a higher sensitivity. Experimental result reveals that the sensor with combined phase core has a higher photo-assisted response. Moreover, the effect of various UV light intensities on TiO2/PANI core-shell nanofiber show maximum response at intermediate UV light intensity. Besides, UV light exposure led to a considerable reduction in recovery and response times to approximately one-fifth of their value. Ammonia sensing property is also evaluated at different humidity levels upon exposure to UV light and shows that higher humidity content leads to increase in sensor response. High sensitivity and low detection limit as low as 50 ppb under high humidity condition and excellent selectivity for various VOCs make the proposed sensor to be a good candidate for breath analysis applications.