Journal Article

Water-Mediated Proton Hopping on an Iron Oxide Surface

Farberow, Carrie A., Besenbacher, Flemming, Rieboldt, Felix, Kudernatsch, Wilhelmine, Merte, Lindsay R., Wendt, Stefan, Grabow, Lars C., Mavrikakis, Manos, Lægsgaard, Erik, Peng, Guowen, Bechstein, Ralf

2012

Overview

The diffusion of hydrogen atoms across solid oxide surfaces is often assumed to be accelerated by the presence of water molecules. Here we present a high-resolution, high-speed scanning tunneling microscopy (STM) study of the diffusion of H atoms on an FeO thin film. STM movies directly reveal a water-mediated hydrogen diffusion mechanism on the oxide surface at temperatures between 100 and 300 kelvin. Density functional theory calculations and isotope-exchange experiments confirm the STM observations, and a proton-transfer mechanism that proceeds via an H₃O⁺-like transition state is revealed. This mechanism differs from that observed previously for rutile TiO₂(110), where water dissociation is a key step in proton diffusion.

• Publisher: American Association for the Advancement of Science,The American Association for the Advancement of Science
• Subject: Atoms / Catalysts / Chemical compounds / Condensed matter: structure, mechanical and thermal properties / Density / Density functional theory / Diffusion / Diffusion; interface formation / dissociation / Exact sciences and technology / ferrous oxide / High speed / Hydrogen / Hydrogen atoms / Iron oxides / Lewis acids / Materials / Mathematical analysis / Metal oxides / Microscopy / Molecular structure / Molecules / Monolayers / Oxides / Physics / Protons / Scanning tunneling microscopy / Solid surfaces and solid-solid interfaces / surface temperature / Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties) / Thin films / Titanium dioxide / Water / Water temperature