Reduced graphene oxide (rGO) decorated NiO-SnO2 nanocomposite based sensor towards room temperature diabetic biomarker detection

In the present work, reduced graphene oxide (rGO) decorated NiO-SnO2 nanocomposites were synthesized by using a facile sol-gel process and their structural (XRD, FTIR, Raman), morphological (BET, FESEM, TEM), and optical (UV-Vis, PL) characterizations were carried out. The as-synthesized NiO-SnO2 nanocomposite exhibited an enhancement of surface area after the incorporation of rGO and this substantial increment was expected to be beneficial for gas sensing at room temperature. Therefore, Taguchi-type sensors were fabricated and deployed for the detection of VOCs. The optimized sensor containing similar to 3 wt% rGO in NiO-SnO2 nanocomposite demonstrated an excellent sensing response (Rg/Ra similar to 7.8) towards similar to 10 ppm acetone at room temperature (30 +/- 5 degrees C) with response and recovery time of similar to 10 s and similar to 30 s respectively. It also exhibited good reproducibility and stability over similar to 3 months. Additionally, this sensor selectively detected trace concentration (< 1 ppm) of acetone in exhaled human breath (ethanol present in a healthy person's exhaled breath is insignificant), which is a non-invasive biomarker of diabetes. The sensing performance was analyzed from an electronic transportation point-of-view and consequent band structure modulation. The electrical property of the sensing material was illustrated using impedance spectroscopy to support the sensing mechanism.