Zinc oxide nano-crystals assisted for carbon dioxide gas sensing; prepared by solvothermal and sonochemical methods

ZnO nanostructures of different methods and sizes were grown in a controlled manner using a simple hydrothermal and sonochemical technique. Controlling the content of concentration and temperature of the reaction mixture, spherical nanoparticles ZnO structures could be synthesized at temperatures 100-150 °C with excellent reproducibility in solvothermal and at different power and time in sonochemical methods. These ZnO nanostructures have been tested for CO2 gas monitoring by depositing them as thick films on an inter-digitated alumina substrate and evaluating the surface resistance of the deposited layer as a function of operating temperature and CO2 concentrations. The gas sensitivity tests have demonstrated that the ZnO nanostructures, spherical morphology, exhibit high sensitivity to CO2 proving their applicability in gas sensors. The role of the nanostructure on the sensing properties of ZnO is also discussed.