Impedance spectroscopy analysis on reduced graphene oxide and CeO2 nanocomposites coated on screen-printed alumina substrate for highly selective H2S gas detection at room temperature

Abstract

Impedance spectroscopic-based gas sensing analysis is a highly sensitive technique. Impedance and its fitted RC circuits provide us with fundamental information about grain boundary, grain bulk, and the interface between sensing film and electrode contact. In this work, an n-CeO2/rGO composite-based gas sensing film with high selectivity, sensitivity, stability and moisture resistance potency for the detection of H2S was developed on screen-printed alumina substrate using a drop casting process, and the H2S gas sensing performance was evaluated using electrochemical impedance spectroscopy (EIS) at various temperatures. The n-CeO2/rGO-3 composite produced stable and rapid responses towards H2S with a response of 97.41 % for 50 ppm of H2S gas at the optimum temperature of room temperature (27 °C). The LOD and LOQ were calculated and found to be ∼0.9 and ∼2.9 ppm for n-CeO2 and n-CeO2/rGO-3 composites, respectively. The superior selectivity with interfering gases such as NH3, H2, SO2 and CO, response and recovery time (∼9s and ∼12s), long-time stability and gas sensing mechanism were investigated. This impedance-based gas sensor development opens up the path for the fabrication of n-CeO2/rGO composite-based H2S gas sensors for future applications.