Liquefied petroleum gas sensing performance of solochemically synthesized ZnO nanorods: Role of precursors and fractal analysis

Nanorods of ZnO were grown successfully using a template free solochemical route using zinc chloride, zinc nitrate and zinc acetate precursors at 70 °C. The structural and morphological analysis of synthesized all ZnO samples were tested by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscopy (TEM) techniques. Whole pattern fitting of XRD patterns shows less strain in unit cell is observed in case of ZnO sample synthesized from zinc chloride precursor. Variations in aspect ratios of ZnO nanorods synthesized using different precursors were observed from TEM results. The ZnO nanorods composed thin films were fabricated via spin coating technique and its liquefied petroleum gas (LPG) sensing performance was investigated. The surface topographical studies and fractal analysis of these films were examined by atomic force microscopy (AFM). These results reveals that thin film composed ZnO nanorods prepared using zinc chloride precursor possess average roughness ~133 nm and fractal dimension ~ 2.42, which is higher than other films. This film exhibits maximum gas response ~502 towards 50 ppm LPG, along with low response and recovery time, repeatability, great selectivity as compared with thin films synthesized from other precursors. The reason of enhancement of gas response for ZnO thin film synthesized using precursor zinc chloride as compared to zinc acetate and zinc nitrate is explained on the basis of aspect ratio and fractal roughness. The LPG sensing mechanism towards ZnO nanorod is also discussed.