I-V characteristics and adsorption properties of ZnO/rGO/ZnO for gas sensing detection

Abstract

The heterostructure consisting of zinc oxide and reduced graphene oxide (ZnO/rGO/ZnO) is prepared on cotton fabric by repeated immersion and magnetron sputtering. In addition, the gas selectivity of the sample is analyzed based on I-V characteristics under different gas atmospheres (air, methanal, ethanol, acetone and toluene). Compare with that in air atmosphere, the I-V characteristic curve under toluene gas atmosphere changes significantly, and the current decreased significantly. The experimental results show that the samples exhibit high selectivity. In order to study the intrinsic physical characteristics of the heterostructure after gas adsorption, the band structures, density of states (DOS), adsorption energy (Ead) and charge density difference (CDD) are calculated based on density function theory (DFT). The existence of rGO results in a high electrical conductivity, which is consistent with the experimental results. Meanwhile, toluene has the highest Ead (-0.85 eV) and charge transfer (0.67 e). The charge transfer results prove that a large number of electrons are transferred from the surface of the heterostructure to the vicinity of toluene molecules, which leads to a change in the electrical conductivity of the heterostructure. Based on the excellent gas selectivity, the application of cotton-based ZnO/rGO/ZnO structure in gas sensing field is promoted.