Mechanism of Fast Proton Transport along One-Dimensional Water Chains Confined in Carbon Nanotubes

A reactive molecular dynamics simulation employing the multistate empirical valence bond (MS-EVB) methodology is reported for the hydration structure of an excess proton in a (6,6) carbon nanotube as well as for the mechanism of proton transport (PT) within the nanoconfined environment. The proton is found to be hydrated in a distorted Zundel cation (H5O2+) form within the one-dimensional, confined water chain. Proton transfer events occur via a Zundel-Zundel mechanism through a transient H7O3+ intermediate that differs significantly from the Eigen-Zundel-Eigen mechanism found in bulk water.