Barrier Height Breakpoint in Employing the Arrhenius Equation to Proton Isotope Permeation through Stone-Wales Graphene.

Abstract

Although the Arrhenius equation has been used in proton isotope transfer across graphene membranes, concerns have arisen about its validity in this scenario. As the strong quantum tunneling during the permeation would cause curvature from the conventional linear Arrhenius plot, it potentially results in misleading activation energies. Here, we investigate the validity of the Arrhenius equation in proton isotope permeation through the topological Stone-Wales 55-77 graphene and report the actual effective activation energy of the permeation. We show that the Arrhenius equation breaks down in proton permeation through a conventional six-membered ring (6MR), in contrast to the normal Arrhenius behavior in a seven-membered ring (7MR). Notably, we demonstrate a barrier height breakpoint beyond which the Arrhenius equation becomes invalid. This study offers an important reference point of the Arrhenius equation, which could provide new insight into the future to accurately determine effective activation energies.