Sensitivity enhancement of ammonia gas sensor based on Ag/ZnO flower and nanoellipsoids at low temperature

• Published in: Sensors and actuators. B, Chemical Vol. 255; pp. 672 - 683
• Main Authors: R., Sankar Ganesh, M., Navaneethan, Patil, V.L., S., Ponnusamy, C., Muthamizhchelvan, Kawasaki, S., Patil, P.S., Hayakawa, Y.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-02-2018; Elsevier Science Ltd
• Subjects: Ag/ZnO Composite; Ammonia; BET analysis; Detection; Emission analysis; Gas sensors; Low temperature; Morphology; Nanoellipsoids; Nanoflower; Nanorods; Nanostructured materials; Optical properties; Scanning electron microscopy; Scanning transmission electron microscopy; Sensitivity enhancement; Silver; STEM; Transmission electron microscopy; Zinc oxide; Zinc oxides; Nanoellipsoids; Nanoflower; Ammonia; Ag/ZnO Composite; BET analysis; STEM
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2017.08.015

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•ZnO nanorods, Silver-doped ZnO nanoflower and nanoellipsoids were successfully synthesized.•SZO nanoellipsoids had wider optical absorption region than ZnO nanorods.•Silver-doped ZnO showed fast gas response and recovery time at 10ppm of ammonia concentration.•Silver-doped ZnO (6%) showed maximum response of 29 for 100ppm at 150°C.
High sensitivity ammonia gas sensor based on Ag/ZnO composite (SZO) nanostructures and their structural, optical, morphological and gas sensing properties were investigated. Field- emission scanning electron microscopy and high- resolution transmission electron microscopy revealed that pure ZnO flower-like nanorods transformed into nanoellipsoids upon adding of silver (Ag). Scanning transmission electron microscopy (STEM) analysis showed clear flower-like morphology of Ag/ZnO composite. STEM-mapping measurement showed that Zn, Ag and O were homogeneously distributed. The ammonia gas sensing analysis revealed that the Ag/ZnO (6wt%) showed higher gas response compared with other content of Ag wt%. Ag/ZnO (6wt%) exhibited the highest response of 29.5 when exposed to 100ppm ammonia gas. Interestingly, Ag/ZnO (6wt%) possessed good response and recovery property of 13 and 20s at low concentration of ammonia at 10ppm, respectively. The mechanism of gas sensing and enhanced gas response of pure ZnO and Ag/ZnO composite was discussed.