Synthesis, characterisation and gas sensing application of nano ZnO material

Abstract

Zinc oxide (ZnO) nanomaterial was synthesised by hydrothermal method. The formation of ZnO nanoparticles were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and UV studies. XRD analysis confirmed the powder to be ZnO with wurtzite structure, with crystallite size ranging from 5 to 25 nm. Observation from TEM images confirmed that the grains were nearly hexagonal rod type in nature with sizes from 22 to 56 nm. The thick films of nano ZnO were prepared by screen-printing technique in desired pattern. The surface morphology of the films was studied by scanning electron microscopy (SEM). The gas sensing performance of the materials have been investigated for various interfering gases such as CO, Cl2, NH3 and H2S etc at operating temperature varying from 50°C to 400°C. The results indicate that the nano ZnO material thick film showed much better gas response than the usual ZnO materials to H2S gas (100ppm) at 250°C. The nanoshaped hexagonal rod would improve the sensitivity and selectivity of the sensors. The selectivity, response and recovery time of the sensor were measured and presented. ZnO nanomaterial is excellent potential candidates for gas sensors.