Giant Enhancement of Hydrogen Transport in RutileTiO2at Low Temperatures

Abstract

Measurements of the O-H and O-D vibrational lifetimes show that the room-temperature hydrogen diffusion rate in rutile TiO2 can be enhanced by 9 orders of magnitude when stimulated by resonant infrared light. We find that the local oscillatory motion of the proton quickly couples to a wag-mode-assisted classical transfer process along the c channel with a jump rate of greater than 1 THz and a barrier height of 0.2 eV. This increase in proton transport rate at moderate temperatures provides new insight into hydrogen transport in solids, which could play a role in applications ranging from fuel cells to hydrogen production.