Confinement Effects on the Properties of Polar Hydrogen-Bonded Fluids: A Showcase on Methanol Adsorbed in Three-Dimensional Pillared Graphene and Carbon Nanotube Networks

Abstract

The confinement effects on the structural and dynamic properties of methanol were investigated by employing Monte Carlo and molecular dynamics simulations using three-dimensional pillared graphene and carbon nanotube networks as model nanoporous materials. The calculated adsorption isotherms of methanol revealed that these types of carbon-based nanoporous materials could be efficient for the adsorption of methanol. The calculations also revealed significant intermediate and large-scale fluctuations in the local intermolecular structure and orientational order of methanol under confinement at ambient temperature and pressure conditions. These fluctuations depend strongly on the adsorbent material and also affect the local dielectric properties of confined methanol. The dynamics of the local hydrogen bonding network as well as the transport, single, and collective dynamics of the confined methanol molecules also change significantly upon confinement, particularly in the case of the carbon nanotube networks. It was also revealed that the confinement affects more strongly the relaxation phenomena occurring at long-time scales, such as the dielectric relaxation and reorientational and intermittent hydrogen bond dynamics.