Physicochemical investigations of Pd2+ substituted ZnO nanoflowers for liquefied petroleum gas sensing.

Present study portrays, physicochemical investigations of pristine and Pd²⁺ modified ZnO nanoflowers (NFs) compositional series [Zn_(1−x)Pd_xO NFs; where x = 0, 0.01, 0.03, 0.05, and 0.07] synthesized via sol–gel reaction route. X-ray diffractogram of all the compositions displayed hexagonal wurtzite type crystallinity with P6₃mc space group without any traces of impurities as confirmed from Rietveld refinement technique. It was found that the average crystallite size increased from 32 to 74 nm with Pd²⁺ intrusion in the crystal lattice framework of ZnO. FESEM micrographs depicted that the surface morphology of pure and Pd modified compositions exhibit flower-shaped surface morphology. The optical properties of as-synthesized NFs were carried out using UV–vis spectroscopy and it was observed that optical energy bandgap (E_g) decreased minutely by Pd²⁺ doping. To determine the gas sensing behavior of synthesized NFs, the prepared gel during material fabrication was used to cast thin films. The thin films were calcined at 600 °C for LPG gas sensing activity and it was observed that the transient curve shows a high response for the composition x = 0.03 for the concentration of 2000 ppm. The present result illustrates that synthesized NFs showed potential candidature for LPG gas sensing. The present study reveals synthesized NFs showed potential candidature for LPG gas sensing 80 °C with a gas sensitivity of 315%. [ABSTRACT FROM AUTHOR]