Development of the Zn-ZnO(Nw)@CuMnO₂ Heterojunction by Low Temperature Zn Foil Oxidation for Gas Sensor Fabrication

In this study, the Zn-ZnO(Nw)@CuMnO2 heterostructure was successfully achieved by deposition of a bidimensional CuMnO2 film on the ZnO nanowires (NWs) layer, by the spin coating method. The novelty of this research is related to the growth of ZnO NWs by thermal oxidation at low temperatures, below the melting point of the Zn foil in a controlled atmosphere consisting of a mixed flow gas, Ar and O-2. The structural and morphological properties of the heterostructures were assessed by XRD, UV-Vis, and SEM techniques. The as-obtained gas sensors based on Zn-ZnO(Nw)@CuMnO2 heterostructures were tested to detect 400 ppm. CO2 concentration at variable testing temperatures inside the testing chamber. The maximum sensibility value of 85.5% was obtained at the lowest operating temperature of 150 degrees C for the ZnONw5@CMO sensor, and when the temperature was increasing to 200 degrees C the sensibility response of 95.4% was recorded for the ZnONw7@CMO sensor. Current-voltage and current-time measurements were performed under different conditions to assess the heterojunction behavior and sensibility of the gas sensor.