Controlled functionalization of single-walled carbon nanotubes for enhanced ammonia sensing: a comparative study

Electrochemically controllable functionalization of single-walled carbon nanotubes (SWNTs) with poly(N-methyl pyrrole) (P[NMP]) is demonstrated for room temperature gas sensing applications. Comparative investigations reveal that the loading content of the functionalization entity has prominent effects on the sensing characteristics of SWNTs. The optimized sensing backbone (P[NMP]-functionalized SWNTs with 5 mu C deposited charge) exhibited a lower detection limit of 10 ppb and excellent linearity for a detection window of 10 ppb-01 ppm concentration of NH3. The typical response and recovery time of the optimized sensor is on the order of minutes. Finally, a performance comparison of the P[NMP]-functionalized SWNT sensing backbones with the pristine P[NMP] nanowire sensor ensured the well-defined role of SWNTs in the functionalized structure. The proposed sensing mechanism suggests that the synthesis parameters can be manoeuvered for the highest operational efficiency of the sensors.