Giant Enhancement of Hydrogen Transport in Rutile TiO2 at 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 nine 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. Such an increase in proton transport rate at moderate temperatures is significant for renewable energy applications ranging from hydrogen fuel cells to water splitting by photo-catalysis.