Gas sensing of 2D materials: Graphene Oxide, Phosphorene, Molybdenite, and WS2

Seyed Mahmoud EMAMJOMEH, Università degli Studi dell'Aquila

Two-dimensional (2D) materials like graphene (G), graphene oxide (GO), phosphorene (P) and more recently transition metal dichalcogenides (TMDs) have attracted tremendous interest for gas sensing applications considering their high surface to volume ratio, wide range of chemical compositions and their unique thickness-dependent physical and chemical properties.  Graphene, by virtue of its fast electron transport kinetic and low electronic noise has shown NO2 gas detection limits down to few ppm. Insulating GO has been successfully functionalized with oxygen containing groups, with enhanced gas sensitivity, improved limits of detection and reduced humidity cross-interference.  More recently new layered materials where tested for gas sensing applications. Among them few layers black Phosphorous, usually referred as Phosporene, demonstrated room temperature gas sensing properties to both NO2 oxidizing and NH3.

TMDs, chemically represented by the MX2 formula where M is a transition metal of group VI (i.e. Mo, W) and X is a chalcogen (i.e. S, Se, Te), can be easily exfoliated to mono or few layers by different routes yielding ultra-high surface-to-volume ratio structures with controlled number of layers. Unlike G and rGO, MX2 exhibit peculiar properties like versatile chemistry, wide range of catalytic properties and layer-dependent tunable electrical response ranging from semiconducting to metallic.

This short communication reports some typical applications of 2D layered materials and their applications as NO2, H2, NH3 gas sensors. Preparation conditions and both microstructural and electrical characterization techniques are presented and discussed. Gas sensing properties in terms of detection limits, long term stability are also compared with literature.

 
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