posted on 2024-02-21, 10:29authored byDario Calvani, Bas Kreupeling, G. J. Agur Sevink, Huub J. M. de Groot, Grégory F. Schneider, Francesco Buda
A fundamental understanding of proton transport through
graphene
nanopores, defects, and vacancies is essential for advancing two-dimensional
proton exchange membranes (PEMs). This study employs ReaxFF molecular
dynamics, metadynamics, and density functional theory to investigate
the enhanced proton transport through a graphene nanopore. Covalently
functionalizing the nanopore with a benzenesulfonic group yields consistent
improvements in proton permeability, with a lower activation barrier
(≈0.15 eV) and increased proton selectivity over sodium cations.
The benzenesulfonic functionality acts as a dynamic proton shuttle,
establishing a favorable hydrogen-bonding network and an efficient
proton transport channel. The model reveals an optimal balance between
proton permeability and selectivity, which is essential for effective
proton exchange membranes. Notably, the benzenesulfonic-functionalized
graphene nanopore system achieves a theoretically estimated proton
diffusion coefficient comparable to or higher than the current state-of-the-art
PEM, Nafion. Ergo, the benzenesulfonic functionalization of graphene
nanopores, firmly holds promise for future graphene-based membrane
development in energy conversion devices.