Fabrication and investigation of TiO1.5/ZnO nanocomposite nanosensor for detection of CO and CH4 gases

Abstract

In this study, a Zn thin film was deposited on a quartz substrate by DC magnetron sputtering. ZnO nanoparticles were then synthesized by thermal oxidation of this thin film in the air at 700°C for 1 h. Afterward, structural properties of nanostructured ZnO films were studied through XRD spectroscopy, FESEM, EDX and AFM images. Results indicated that the prepared nanosized ZnO particles, which have a porous form with a wurtzite structure, are uniformly distributed on the surface and that the features of porosity and uniformity can greatly improve the sensing properties of ZnO sensors. Then, a thin film of Ti was deposited on ZnO by DC magnetron sputtering, and, subsequently, 100 nm of Au electrodes were used to cover it by evaporation method. Finally, the sample was sintered in airflow at 150°C for 1 h, and the TiO1.5 nanoparticles were formed from sputtered Ti thin film in the uncovered area between Au contacts. Prepared sensors were tested at 300°C of substrate for different concentrations of CH4 and CO gases. Experiments indicated that compared to similar ZnO sensors, the sensitivity of the TiO1.5/ZnO nanosensor to CH4 and CO gases significantly improved, whereas it is not influenced by H2 gas. These data suggest that gas detection by TiO1.5/ZnO nanocomposite, produced by optimizing the manufacturing conditions, can detect minuscule traces of CH4 and CO gases with very high sensitivity and stability as well as better response (Rgas/Rair) in comparison with previous ZnO-based sensors.