Aqueous Proton Transfer Across Single Layer Graphene
Abstract
Proton transfer across single layer graphene is associated with large computed energy barriers and is therefore thought to be unfavorable at room temperature unless nanoscale holes or dopants are introduced, or a potential bias is applied. Here, we subject single layer graphene supported on fused silica to cycles of high and low pH and show that protons transfer reversibly from the aqueous phase through the graphene to the other side where they undergo acid-base chemistry with the silica hydroxyl groups. After ruling out diffusion through macroscopic pinholes, the protons are found to transfer through rare, naturally occurring atomic defects. Computer simulations reveal low energy barriers of 0.68 to 0.75 eV for aqueous proton transfer across hydroxyl-terminated atomic defects that participate in a Grotthuss-type relay, while pyrylium-like ether terminations shut down proton exchange. Unfavorable energy barriers to helium and hydrogen transfer indicate the transfer process is selective for aqueous protons.
Keywords
Cite
@article{arxiv.1411.1034,
title = {Aqueous Proton Transfer Across Single Layer Graphene},
author = {Jennifer L. Achtyl and Raymond R. Unocic and Lijun Xu and Yu Cai and Muralikrishna Raju and Weiwei Zhang and Robert L. Sacci and Ivan V. Vlassiouk and Pasquale F. Fulvio and Panchapakesan Ganesh and David J. Wesolowski and Sheng Dai and Adri C. T. van Duin and Matthew Neurock and Franz M. Geiger},
journal= {arXiv preprint arXiv:1411.1034},
year = {2017}
}
Comments
80 pages, including Supporting Information, 3 Figures, 1 Table, final pre-edited version