Quenching of oxygen-related defects in graphene oxide nanohybrid: Highly selective room-temperature ethanol sensor

Abstract

The presence of surface defects, such as epoxy and carbonyl groups, is known to control the charge-carrier transport in graphene oxide (GO). In addition, these surface entities also provide an opportunity to synthesize novel hybrid (NH) materials via chemical bonding. These hybrid materials are particularly interesting for sensing as they offer novel properties like larger surface area and improved physical/chemical properties. Herein, we are proposing a novel SiO2@GO–NH based room-temperature (RT) ethanol sensor. The NH is realized from solution-route by following the sol–gel chemistry of tetraethyl orthosilicate. The attachment of SiO2 with the GO network occurs via the formation of Si–O–C bonds, which also leads to the reduction in the atomic percentage of electron-withdrawing groups. This reduction results in the improvement in electron charge transport in GO, which leads to the RT detection of ethanol. Specifically, the charge transport in NH is found to be dominated by a field-driven temperature-independent 2D variable-range hopping mechanism. While the ethanol sensing mechanism is found to be governed by two processes, i.e., via direct interaction of ethanol with NH and interaction with chemisorbed oxygen ions on the Pt/Si@GO–NH interface. Detailed observations reveal that the SiO2–GO NH has great potential to be used as a biomarker for food quality control.