Effect of oxygen-containing groups in functionalized graphene on its gas sensing properties

Abstract

The creation of active material for chemiresistive gas sensors with high selectivity and sensitivity will allow a step towards miniaturization and reduction of power consumption of portable gas sensors. Graphene is a promising platform for the synthesis of two-dimensional active materials with high sensitivity. In this work, applying density functional theory (DFT) calculations, the effect of oxygen-containing functional groups (O, OH, O, COOH) on the adsorption of small gas molecules (NH3, CO2, CO, H2S, NO2, SO2) was rigorously studied. Based on the adsorption energies and partial charges from DFT calculations, the sensitivity and selectivity of graphene with different functionalizations were predicted. It was found that hydroxyl and carboxyl groups demonstrate increased selectivity and sensitivity of gas sensors, and the edge of graphene with hydroxyl groups shows the highest enhancement. Graphene with a carbonyl group was found to undergo irreversible chemisorption of NO2, which can potentially cause active material degradation, limiting the recyclability of gas sensors. Most of the molecules show both donor and acceptor behavior, which highlights the importance of a thorough selection of specific functional group types. The obtained results are useful for the rational design of graphene-based active material with oxygen-containing functional groups for chemiresistive gas sensors.