Ultrasensitive NH₃ Gas Sensor from Polyaniline Nanograin Enchased TiO₂ Fibers

In this communication, we reported for the first time an ultrasensitive nanostructrued sensor that can detect 50 ppt of NH 3 gas in air. Specifically, nanograins of a p-type conductive polymer, polyaniline (PANI), are enchased on an electrospun n-type semiconductive TiO 2 fiber surface. The resistance of the p−n heterojunctions combining with the bulk resistance of PANI nanograins can function as electric current switches when NH 3 gas is absorbed by PANI nanoparticles. As a result, the sensor sensitivity can be significantly improved. The sensor fabricated in this work is 1000 times more sensitive than the best PANI sensor reported in the literature.