Unraveling the impact of nitrogen doped graphene on the sensing of volatile organic compounds: a dft study

Understanding the interaction mechanisms between volatile organic compounds (VOCs) with graphene-based materials is the primary and crucial step for human health and the advancement of digital olfaction. In this study, we investigated the adsorption behavior of four common odor molecules (toluene, ethanol, 2-Furfurylthiol, and guaiacol) on various graphene-based substrates, including pristine graphene, graphene doped with single graphitic-N atom (GR-N), and multiple pyrodinic-N atoms (1pd-N, 2pd-N, 3pd-N, and 4pd-N) using density functional theory. The adsorption energies and Bader charge analysis for all adsorption cases demonstrated that the molecules were weak physisorbed on all substrates. Through the work function change comparison, 2pd-N and N-gra presents likely promising sensing performance towards the odor molecules, while the selectivity declines by further introducing 3 and 4 pyrodinic-N atoms into graphene. The surface dipole moment analysis shed light on the underlying mechanism of work function change and explained the reduced sensitivity and selectivity observed for 3pd-N and 4pd-N, which can be attributed to a decrease in the molecule-induced dipole moment and increase in spatial charge redistribution. These findings could contribute to the fundamental understanding of odor molecule-graphene interactions and provide insights for the design and optimization of graphene-based electronic olfaction devices.