Sensitive and Reversible Ammonia Gas Sensor Based on Single-Walled Carbon Nanotubes

Abstract

The present study reports on the fabrication and performance of ammonia sensors based on single-walled carbon nanotubes (SWCNTs) coated with gold nanoparticles (AuNPs). The sensors were subjected to controlled concentrations of ammonia at two temperatures, namely 25 oC and 140 oC, and their response was monitored through successive cycles of ammonia exposure and nitrogen purging. The results demonstrate that the sputtering-based deposition of AuNPs on SWCNTs led to the best sensor performance, characterized by a rapid increase in resistance values upon exposure to ammonia, and efficient recovery at 140 oC. By contrast, the sensor with chemically impregnated AuNPs exhibited a slower response time. Furthermore, a novel device was developed that combined MoS2-AuNPs (sputtering)-SWCNTs, and it showed improved sensor performance compared to the devices with only AuNPs. Overall, the study provides valuable insights into the fabrication and optimization of SWCNT-based ammonia sensors for various applications, especially for detecting and quantifying small amounts of ammonia (concentrations below 1 ppm).