Comparison of the Sensing Properties of ZnO Nanowalls-Based Sensors toward Low Concentrations of CO and NO2

Elena Bruno,Nicola Donato,Giovanni Neri,Salvo Mirabella,Salvatore Leonardi,Vincenzina Strano

doi:10.3390/chemosensors5030020

Elena Bruno, Nicola Donato + Show 4 more

Open Access

https://doi.org/10.3390/chemosensors5030020

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Journal: Chemosensors	Publication Date: Jul 4, 2017
Citations: 18	License type: CC BY 4.0

Affiliation: University of Catania, University of Messina

Abstract

This work focuses on the synthesis and gas sensing properties of ZnO nanowalls (ZnO NWLs) grown by a simple cheap chemical bath deposition method on a thin layer of aluminum (about 20 nm thick) printed on the Pt interdigitated electrodes area of conductometric alumina platforms. Post-deposition annealing in nitrogen atmosphere at 300 °C enabled the formation of a ZnO intertwined 2D foils network. A wide characterization was carried out to investigate the composition, morphology and microstructure of the nanowalls layer formed. The gas sensing properties of the films were studied by measuring the changes of electrical resistance upon exposure to low concentrations of carbon monoxide (CO) and nitrogen dioxide (NO2) in air. The sensor response to CO or NO2 was found to be strongly dependent on the operating temperature, providing a means to tailor the sensitivity and selectivity toward these selected target gases.

Highlights

ZnO is one of the most studied and practically used metal oxides for conductometric gas sensors, since Seyama demonstrated that these simples and low-cost devices are very effective for monitoring gaseous species at very low concentrations [1]
It is noteworthy that such a thin layer is partially oxidized during the chemical bath deposition (CBD), so it will not act as a short circuit between that such a thin layer is partially oxidized during the CBD, so it will not act as a short circuit between electrodes
We demonstrated the interesting sensing characteristics toward carbon monoxide (CO) and NO2 of ZnO nanowalls grown on conductometric platforms

Summary

Introduction

ZnO is one of the most studied and practically used metal oxides for conductometric gas sensors, since Seyama demonstrated that these simples and low-cost devices are very effective for monitoring gaseous species at very low concentrations [1]. The research in the field of gas sensing has looked at the nanotechnology processes for making new nanostructures. Among the various typologies of ZnO nanostructures, nanowalls (ZnO NWLs) have attracted increasing interest because of their huge surface-to-volume ratio and extremely thin wall thicknesses [2]. These particular nanostructures can be prepared by different methods, both in liquid and gas phase [3,4,5]. While gas phase deposition techniques typically require an operating temperature higher than 800 ◦ C, several chemical methods based on aqueous zinc solutions allow the preparation of ZnO NWLs below Nanostructured materials have shown improved sensing properties with respect to the bulk ones, and are expected to replace them in many advanced application areas such as, automotive, aerospace, biomedical, environmental, and so on.

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