Solid-state synthesis strategy of ZnO nanoparticles for the rapid detection of hazardous Cl2

In the present study, rapid and highly efficient solid-state synthesis strategy has been successfully employed for the synthesis of zinc oxide nanoparticles (ZnO NPs). Herein, prepared ZnO NPs are characterized and used for the fabrication of highly sensitive, selective, and accountable gas sensors. Structural elucidation, surface composition, and morphological investigations of as-synthesized ZnO NPs respectively, are carried out using X-ray diffraction, Raman spectroscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction measurement techniques. The gas sensing properties of ZnO NPs studied at various operating temperatures and towards different oxidizing and reducing gases demonstrated the ability of ZnO to detect hazardous chlorine (Cl2) gas (optimum @ 200 °C) with rapid response and recovery times. In addition, ZnO sensor film has detected the low 5 ppm concentration of Cl2 with reasonable response of 199% with outstanding repeatability and stability in response. The variation of ZnO response with respect to different Cl2 concentrations has systematically been investigated and explored. Finally, the plausible sensing mechanism of ZnO with Cl2 gas molecules has been proposed using energy band model diagram.