Single step synthesis of ZnO nanostructure thick films and its application as CO gas sensor

Single step synthesis of ZnO nanostructure thick films gas sensor has been adopted by using zinc metal as precursor. The ZnO was coated directly onto the alumina substrate by just spreading zinc powder using glass slides and then firing at 700°C for 1,2 and 3 hour and the film nicely adhere to the substrate. The surface morphology was studied using SEM which revealed the formation of different structures such as tetrapods, nanowires and porous structure onto the substrate. The crystal structure of ZnO was observed through X-ray diffraction to be hexagonal wurzite but containing small amount of zinc. UV Absorption spectroscopy shows the blue shift in the wavelength than the bulk ZnO, while blue emission is observed Photoluminescence Spectroscopy with the defect states at the near band edge. Also Raman Spectroscopy was performed in order to study the vibrational modes of ZnO nanostructures in the wavelength range of 200–1100nm. Thus prepared ZnO thick films were tested for 50–150ppm of CO gas in static chamber of volume 24 liters.