Enhanced gas sensing performance of ZnO and Pt-doped ZnO nanostructured films by chemical spray pyrolysis

This study focuses on the preparation and characterization of zinc oxide (ZO) and platinum-doped zinc oxide (PtZO) nanostructured thin films using the chemical spray pyrolysis technique. Structural and morphological properties of the films were investigated via X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). To understand the semiconducting nature and carrier dynamics, UV-Vis spectroscopy, electrical conductivity measurements, and a static gas sensing system were employed. The films exhibited crystallization in the hexagonal wurtzite structure with a preferred orientation along the (002) plane. FESEM images revealed the presence of small bright particles, particularly abundant in the 5 wt% Pt-doped ZO thin film, indicating the presence of platinum catalysts. Electrical conductivity measurements confirmed the semiconducting nature of the films. Optical parameters such as band gap and absorption index were obtained from UV-Vis spectroscopy. Gas sensing performance towards liquefied petroleum gas (LPG) showed that the 5 wt% Ptdoped ZO thin film exhibited a high response (69.9) to a 50 ppm concentration of LPG at 350 degrees C. The gas response and recovery times were observed to be 8 s and 12 s, respectively. These results are attributed to interactions between LPG molecules and adsorbed oxygen species on the sensor surface. Platinum atoms on the oxide surface facilitate the formation of oxygen vacancies and the dissociation of oxygen molecules at low temperatures, leading to increased adsorption and reaction with LPG molecules. This results in significant changes in the sensor's resistance, thereby amplifying the sensor response. The findings demonstrate the potential of Pt-doped ZO thin films for practical gas sensing applications.