Diffusion versus Desorption: Complex Behavior of H Atoms on an Oxide Surface

Abstract

Adsorption of atomic hydrogen on single-crystalline rutile TiO2(110)-(1×1) (see picture) at room temperature leads to ordered H adlayers with (1×1) periodicity and many vacancies. Unexpectedly, almost no recombinative desorption of H2 (or H2O) occurs on heating to above 600 K, because the activation energy of 1.11 eV for H atoms migrating into the bulk is significantly smaller as shown by DFT calculations.