A NEW CHEMICAL SENSING MATERIAL FOR ETHANOL DETECTION: GRAPHENE-LIKE

In this work, with the aim of realizing an ethanol device operating at RT, we have fabricated a chemi-resistive sensing layer based on a graphene related material (GRM): a so-called graphene-like (GL) layer. These materials are produced starting from a nanostructured carbon black through a two steps oxidation/reduction method under mild conditions and in aqueous environment. The GL layers undergo to self-assembling in thin film on surfaces after drying, driven by the instauration of hydrophobic interactions between the graphenic layers, as typically observed in reduced graphite oxide. Thanks to the presence of residual oxygen functional groups, mainly carboxylic groups, as confirmed by X-ray Photoemission Spectroscopy, atomically flat self-assembly over large areas is enabled at low pH. To assess the ability of the GL-based sensing layer to reveal low concentrations of ethanol at RT, the device was introduced into the gas testing chamber and exposed to 50 ppm of ethanol in dry N2, setting the voltage at 1 V. The device response is defined as the maximum variation of conductance recorded during the exposure of the sensing materials to controlled concentration of analytes, i.e Gmax-G0/G0 where G0 is the electric conductance in the initial unperturbed state. GL material is responsive to this analyte, exhibiting a response of 3% with a Signal-to-noise ratio (SNR) > 40dB. This result is even more astonishing when compared to the detection limits of other devices operating at RT, reported in the literature. From the literature, pristine graphene emerges as totally insensitive to ethanol.