Morphological Effects in SnO2 Chemiresistors for Ethanol Detection: A Review in Terms of Central Performances and Outliers.

Andrea Ponzoni

doi:10.3390/s21010029

Abstract

SnO2 is one of the most studied materials in gas sensing and is often used as a benchmark for other metal oxide-based gas sensors. To optimize its structural and functional features, the fine tuning of the morphology in nanoparticles, nanowires, nanosheets and their eventual hierarchical organization has become an active field of research. In this paper, the different SnO2 morphologies reported in literature in the last five years are systematically compared in terms of response amplitude through a statistical approach. To have a dataset as homogeneous as possible, which is necessary for a reliable comparison, the analysis is carried out on sensors based on pure SnO2, focusing on ethanol detection in a dry air background as case study. Concerning the central performances of each morphology, results indicate that none clearly outperform the others, while a few individual materials emerge as remarkable outliers with respect to the whole dataset. The observed central performances and outliers may represent a suitable reference for future research activities in the field.

Highlights

Metal oxides (MOXs) are among the widest investigated materials in the gas sensing field
This paper reviews the results obtained in the last five years with chemiresistors based on pure SnO2 against ethanol vapors in a dry air background
What most emerges from the analysis are a few, individual materials outperforming the rest of the dataset, while, in terms of central performance, there is no clear evidence for any morphology working better than others

Summary

Introduction

Metal oxides (MOXs) are among the widest investigated materials in the gas sensing field This is thanks to their capability to exhibit large electrical resistance variations upon exposure to low concentrations of different chemicals, and to the availability of cheap synthesis methods compatible with production at large scale [1,2]. Their reduced size, weight and power consumption, merged with their compatibility with silicon technology, makes MOX-based chemiresistors ideal candidates for the development of portable devices [3,4,5]. The first commercial MOX chemiresistor was based on a SnO2 thick film, i.e., a disordered network composed of crystallites with spherical shape, [2] and, along years, several milestones in the understanding of the MOX sensing mechanism have been achieved working with SnO2 thick films, which is considered the reference material in the field [14,15]

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Conclusion