Effects of the crystal reduction state on the interaction of oxygen with rutile TiO2(1Â 1Â 0)

► The barrier for the 2nd O2 dissociation channel decreases with increasing TiO2 reduction state. ► The barrier for Ti interstitial diffusion decreases with increasing TiO2 reduction state. ► The shape of the O2-TPD peak(s) at ∼410 K depends on the crystal reduction state. ► The quantity of O2 desorbing at ∼410 K is non-linear to the crystal reduction state. ► Sub-surface defects such as Ti interstitials enable O2 adsorption on rutile TiO2(1 1 0).