Improving the sensitivity of carbon nanotube sensors by benzene functionalization

The detection of dissociated gas species, generated either by plasma or partial discharge, is of great interest because the dissociated species can alter inherent potential of a gas: for example, the insulating characteristics of SF6. Here we report that the sensitivity of carbon nanotubes (CNTs) about dissociated species of SF6 substantially increases by functionalizing with benzene. The sensors were prepared by the dielectrophoretic deposion of CNTs on microelectrodes. The target analytes were chemisorbed on the benzene-functionalized CNTs, and the sensors also could be regenerated by annealing at around 400 °C. The sensor response was analytically described by the modified Langmuir isotherm model. Through the density functional theory calculations, we identified that SOF3 was particularly influential on the electronic structure of the benzene-functionalized CNTs whereas SOF1, SOF2, SO2F2, and HF showed negligible effects. The proposed functionalization methodology provides insight into how to increase sensitivity of carbon nanotube sensors for the detection of dissociated SF6 species.