Synthesis and characterization of ZnO/SnO2 nanorods core–shell arrays for high performance gas sensors

• Published in: Applied physics. A, Materials science & processing Vol. 127; no. 3
• Main Authors: Alosfur, Firas K. Mohamad, Ridha, Noor J.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2021; Springer Nature B.V
• Subjects: Applied physics; Capping; Characterization and Evaluation of Materials; Condensed Matter Physics; Emission analysis; Energy bands; Energy gap; Ethanol; Excitons; Field emission microscopy; Gas sensors; Machines; Manufacturing; Materials science; Morphology; Nanoparticles; Nanorods; Nanotechnology; Operating temperature; Optical and Electronic Materials; Optical properties; Photoluminescence; Photovoltaic cells; Physics; Physics and Astronomy; Processes; Sensitivity; Sensor arrays; Shells; Surfaces and Interfaces; Thin Films; Tin dioxide; Zinc oxide; Core–shell; ZnO; SnO; Nanorods
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-021-04357-4

In this work, three samples were synthesized; SnO 2 nanoparticles, ZnO nanorods and ZnO/SnO 2 core–shell nanorods. The preparation of the ZnO/SnO 2 composite included two steps, the first was to spin ZnO thin film as a seed layer. The second step is to grow ZnO/SnO 2 to produce core–shell nanorod devices. The structure and morphology of the prepared samples were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Meanwhile, the optical properties were investigated by ultraviolet–visible (UV–Vis) and photoluminescence (PL) spectroscopy. The morphology of the prepared sample revealed that ZnO nanorods were capped by SnO 2 shell. The energy band gap of ZnO/SnO 2 is lower than that of both bare ZnO and SnO 2 . Evaluations to near-band (PL) emission of bare ZnO nanorod arrays were considerably reduced by capping with SnO 2 sell. The performance of the gas sensor was further examined on the basis of ZnO/SnO 2 . The response and sensitivity were measured to be 86.6 ( ± 0.5) at optimum operating temperature of 225 °C toward 100 ppm ethanol vapor, which is even higher than those of the bare ZnO nanorods. The local sites added by the SnO 2 shell layer could probably stop the excitons from becoming captured by intrinsic defects, leading to improved sensitivity of the gas sensor.