Feasibility of carbon nanomaterials as gas sensors: a computational study

Abstract

Carbonaceous materials are a promising class of materials for potential application as chemical and biomolecule sensors. In this work we have done first principles calculations to study the interaction of various small molecules, such as CO₂, H₂O, NH₃, CH₄ and H₂, on the surface of carbon nanotubes (CNTs) and graphene in order to study their feasibility as gas sensors. Model systems for armchair and zigzag CNTs of different diameter have been considered to study the effect of chirality and curvature of the carbon nanomaterials on binding with these small molecules. Our results reveal that these gas molecules have been weakly physisorbed on the surface and act as charge donors to the carbon nanomaterials. Charge transfer between the gas molecules and the carbon materials impacts the physical properties of the carbon materials, which may be traced to their sensitivity. As the gas molecules are physisorbed on the carbon materials, they may be suitable for repetitive sensor operation. Significant changes in the polarizability of the carbon materials have been observed on binding with the gas molecules and monitoring such changes provides valuable guidance in designing optimal gas sensors based on carbon materials that could satisfy the demand in various fields.