Discriminative detection of volatile organic compounds using an electronic nose based on TiO2 hybrid nanostructures

Volatile organic compounds (VOCs) are environmental pollutants that pose risks to the human health even at very low concentrations. Therefore, fast and sensitive analytical methods capable to discriminate VOCs are highly demanded. Herein, we have successfully synthetized and characterized TiO2 nanofibers (NF) by electrospinning and TiO2 nanoparticles (NP) by sol-gel method to be employed in an electronic nose (e-nose) for monitoring VOCs. Electrical comparison between TiO2-NF and TiO2-NP indicated that the former presented better electrical response, which can be attributed to the better charge transfer along the nanofiber framework. The TiO2 nanostructures were combined with three different polymers, namely poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), polypyrrole (PPy), and polystyrene sulfonate (PSS), which obtained nanocomposites were deposit by drop casting onto gold interdigitated electrodes and used as sensing units of the e-nose. Electrical impedance spectroscopy measurements were employed to collect the e-nose electrical resistance data, which were treated by Principal Component Analysis (PCA), revealing the system was able to discriminate the three VOCs. Our results indicate that the e-nose system has potential to be employed as a rapid and simple alternative in the detection of VOCs.