Fabrication, characterization and exploration of cobalt (II) ion doped, modified zinc oxide thick film sensor for gas sensing characteristics of some pernicious gases

Abstract

The present research deals with the synthesis of zinc oxide (ZnO) nanoparticles by the co-precipitation (CPT) method. The CPT method was successfully utilized for the synthesis of ZnO nanoparticles. The structural properties of undoped ZnO and cobalt doped ZnO were confirmed by employing an X-ray diffraction (XRD) study, from which the average particle size for each prepared material was calculated from the Debye Scherer formula. The average particle size confirms the nano range fabrication of undoped and cobalt doped ZnO material. The surface characteristics, morphology, texture, and porosity properties of undoped ZnO and cobalt doped ZnO were investigated from scanning electron microscopy (SEM). The elemental composition was investigated from energy dispersive spectroscopy (EDS). The High-resolution transmission electron microscopy (HRTEM) results revealed the hexagonal phase of prepared material. Furthermore, the undoped ZnO and 5% cobalt doped ZnO gas sensors prepared by screen printing technology were utilized for gas sensing purposes for testing the gases like H2S, NO2, SO2, and methanol. For the gases examined, the cobalt modified ZnO sensor proved to be quite effective, especially for H2S and NO2 gas vapors. The Co2+ doped ZnO sensor showed 70.12% sensitivity for H2S gas at 150 0C and 68.75% gas response for NO2 gas vapors at 120 0C. In addition, the cobalt modified sensor was also investigated for reusability test to get concrete gas response results with the time interval of 15 days. In conclusion, it can be mentioned that the cobalt doped ZnO thick film sensor is a promising sensor for H2S and NO2 gas vapors.