Electrochemically functionalized single-walled carbon nanotubes for ultrasensitive detection of BTEX vapors

Single-walled carbon nanotubes (SWNTs) have been functionalized electrochemically with porphyrin and were employed as the channel to fabricate the chemical field-effect transistor. Tetraphenylporphyrin was chosen for functionalization purpose. The primary aim of this study was to evaluate the sensing performance of functionalized SWNTs for the detection of BTEX vapor and to understand the underlying mechanism for the detection. The functionalization showed a significant enhancement in the sensing response for all analytes starting from 1.25 ppm to 15 ppm of concentration. A sub-ppm limit of detection was also observed. The systematic study of field effect transistor (FET) measurements indicates that the sensing mechanism is dominated by the electrostatic gating effect.