Effect of dispersant on chain formation capability of TiO2 nanoparticles under low frequency electric fields for NO2 gas sensing applications

In this study, the effect of Dolapix CE64 as dispersant on the deposition mechanism and chain formation of TiO2 nanoparticles in the different frequencies under non-uniform AC electric field was investigated. The optical microscope (OM) images of the deposition patterns obtained at the frequency of 1 Hz and 100 Hz in non-aqueous media one containing dispersant and the other being dispersant free revealed that the addition of charge inducing agents (dispersant) has drastically changed deposition mechanism enabling particles to enter the gap leaving the electrodes surfaces uncoated. At 10 kHz, it was observed that by the introduction of Dolapix CE64 the TiO2 nanoparticles were able to form chain-like patterns along the electric field lines bridging the interelectrode gap. The obtained pearl chain formation (PCF) was employed to fabricate an NO2 gas sensor which showed a good response to the target gas at 450, 500 and 550 ˚C.