Enhanced ethanol gas sensing properties of SnO₂-core/ZnO-shell nanostructures

• Published in: Sensors (Basel, Switzerland) Vol. 14; no. 8; pp. 14586 - 14600
• Main Authors: Tharsika, T, Haseeb, A S M A, Akbar, Sheikh A, Sabri, Mohd Faizul Mohd, Hoong, Wong Yew
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 11-08-2014; MDPI
• Subjects: Activated carbon; core-shell nanostructures; Detection; Equipment Design - methods; Ethanol; Ethanol - chemistry; ethanol gas sensor; Ethyl alcohol; Gases; Gases - chemistry; hierarchical nanostructures; Investigations; Metal oxides; Microscopy, Electron, Scanning - methods; Morphology; Nanostructure; Nanostructures - chemistry; Nanowires; Nanowires - chemistry; Particle Size; Scanning electron microscopy; Sensors; SnO2; Temperature; Tin Compounds - chemistry; Tin dioxide; Tin oxides; X-Ray Diffraction - methods; Zinc oxide; Zinc Oxide - chemistry; Zinc oxides; ZnO
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s140814586

An inexpensive single-step carbon-assisted thermal evaporation method for the growth of SnO2-core/ZnO-shell nanostructures is described, and the ethanol sensing properties are presented. The structure and phases of the grown nanostructures are investigated by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. XRD analysis indicates that the core-shell nanostructures have good crystallinity. At a lower growth duration of 15 min, only SnO2 nanowires with a rectangular cross-section are observed, while the ZnO shell is observed when the growth time is increased to 30 min. Core-shell hierarchical nanostructures are present for a growth time exceeding 60 min. The growth mechanism for SnO2-core/ZnO-shell nanowires and hierarchical nanostructures are also discussed. The sensitivity of the synthesized SnO2-core/ZnO-shell nanostructures towards ethanol sensing is investigated. Results show that the SnO2-core/ZnO-shell nanostructures deposited at 90 min exhibit enhanced sensitivity to ethanol. The sensitivity of SnO2-core/ZnO-shell nanostructures towards 20 ppm ethanol gas at 400 °C is about ~5-times that of SnO2 nanowires. This improvement in ethanol gas response is attributed to high active sensing sites and the synergistic effect of the encapsulation of SnO2 by ZnO nanostructures.