Fabrication of Molecularly Imprinted Polymer Films Based on Graphene Oxide and Carbon Nanotubes for Nitrogenous Compound Sensing in Fuel Chemicals

Interdigital electrodes and the newly formed molecularly imprinted polymeric films have been used to track the presence of nitrogenous chemicals like indole carbazole in fuels. Printed circuit boards were used to produce interdigital comb-shaped electrodes with a finger spacing of 130 µm and an electrode width of 300 µm. In imprinted and non-imprinted sensor polymer films, graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) were distributed to enhance the capacitance shift or sensor response. When comparing the signals of the imprinted and non-imprinted layers, there was a significant relative difference when measuring capacitance at a low frequency, or 60 Hz. Both carbazole and indole were present in the measured amounts in the 4–20 ppm range. For both carbazole and indole, it was shown that adding MWCNTs and GO to sensor polymer films dramatically increased sensor responsiveness. The sensor signal was amplified more for GO- rather than CNT-produced sensor layers. This showed that adding GO to polymeric gels results in more uniform layers and that oxygen-bearing functional groups on the surface of GO lead to improved capacitance shift amplification when compared to unmodified CNTs.