Boosting of NO2 gas sensing performances using GO-PEDOT:PSS nanocomposite chemical interface coated on langasite-based surface acoustic wave sensor

Abstract Although the physicochemical properties of graphene oxide-Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (GO-PEDOT:PSS) nanocomposite has widely reported, the urgency of this nanocomposite in the surface acoustic wave (SAW) technology still remains at the infancy stage. In this work, a high response SAW NO2 gas sensor was developed by depositing the GO-PEDOT:PSS nanocomposite on piezoelectric LGS substrate. The pristine LGS SAW sensor has showed a resonant center frequency of 136.10 MHz and it was shifted to 135.78 MHz for the GO-PEDOT:PSS coated LGS SAW sensor. The observed shift in resonance frequency likely due to the mass loading effect of GO-PEDOT:PSS nanocomposite interface. However, under the gas ambient the GO-PEDOT:PSS/LGS SAW sensor exhibited a significant negative differential frequency shift (Δf) of 5.89 kHz to100 ppm of NO2 gas with a good cycling stability, excellent sensitivity and a low detection limit (∼175 ppb) at room temperature (RT), while the pristine GO/LGS and PEDOT:PSS/LGS SAW sensors showed the Δf of about 0.9 kHz and 2.1 kHz, respectively. In addition, under the various relative humidity conditions at RT for 100 ppm of NO2, the GO-PEDOT:PSS/LGS SAW device showed a dominant Δf. Our experimental results divulged that the effect of mass loading is the responsible underlying mechanism for the superior NO2 gas sensing performances. In turn, the predominant mechanism between the chemical interface and NO2 gas molecules on GO-PEDOT:PSS/LGS SAW device has been deliberately discussed in detailed by comparing with chemo-resistive type gas sensing properties These intriguing results indicate that the significance of GO-PEDOT:PSS has a synergetic effect in SAW sensor applications.