AC characterization of three-dimensional reduced graphene oxide/molybdenum disulfide nanorose hybrids for ethanol vapor detection

A novel AC impedance study on three-dimensional hybrid structures of graphene sheets/MoS 2 nanorose (GMS) toward ethanol vapor detection is presented in this work. These defective 3D hybrid porous structures are sensitive to the presence of different gases as a result of charge transfer with gas species, as well as a change in the effective capacitance of the system. The sensing behavior of the samples is investigated throughout time-dependent impedance measurement and electrochemical impedance spectroscopy (EIS). The sensor response is estimated at about 20% to 10 ppm ethanol vapor, with the response and recovery times about 3.2 s and 0.8 s, respectively. Sensing mechanism proposed to describe the EIS impedance spectra involves three different procedures: charge transfer, double layer formation and diffusion process. Moreover, these processes are probed using equivalent circuits modeled by the impedance spectra curves.