Liquid Exfoliated NiO Nanosheets for Trace Level Detection of Acetone Vapors.

Acetone, a colorless volatile organic compound (VOC), is exhaled in large concentrations in the breath of diabetic patients. In this paper, a simple liquid exfoliation technique-based few-layered NiO (111) plane exposed nanosheets (diameter 125 nm) were synthesized [in dimethylformamide (DMF) as solvent] and used as highly selective trace level (15–450 ppm) acetone sensors. The sensors were found to be fast (response and recovery time of 82 and 80 s, respectively) and repetitive with a maximum response of 196% (for 450 ppm acetone). The limit of detection of the device is 830 ppb. The operating temperature of the sensor was optimized at 200 °C in comparison to other reported NiO-based VOC sensors mainly due to high surface energy aiding oxygen adsorption at a lower temperature. An “assistive binding model” is proposed to explain sensor performance in the presence of humid air. The model showed positive sensitivity and binding coefficients (${s}_{a} = {0.242}$ ppm−1 and ${k}_{{{aw}}} = {2.04} \times 10^{-{3}}$), proposing a synergistic effect of water on the sensor response for acetone vapors. [ABSTRACT FROM AUTHOR]