Chemically Functionalized Single-Walled Carbon Nanotubes as Ammonia Sensors

Abstract

This study demonstrates a novel approach toward development of advanced chemical sensors based on chemically functionalized single-walled carbon nanotubes (SWNTs). SWNTs with covalently attached poly( m -aminobenzene sulfonic acid), SWNT-PABS, have shown improved sensor performance for detection of NH 3 . Compared to purified SWNTs, devices fabricated with SWNT-PABS have shown more than 2 times higher change of resistance upon exposure to NH 3 . Importantly, the SWNT-PABS sensors rapidly recover their resistance when NH 3 is replaced with nitrogen. Exposure to NH 3 induces significant changes in the electronic structure of SWNT-PABS, which allow detection of NH 3 at concentrations as low as 5 ppm. Thin film deposited between interdigitated electrodes was explored as a device configuration for development of gas sensors.